V IEWPOINT
Coatings Attendance is Encouraging!! Judging by events held in February for the coatings community and what is scheduled for March and April, I think things are looking up. The World of Concrete event held in February drew over 55,000 registered professionals and over 1,300 exhibiting companies. PACE 2010 was held in about the same time frame and also seemed to have good attendance this year. NACE is scheduled for mid-March and already is showing over 5,000 registered and 350 exhibiting companies. All in all I think that is a good start to the 2010 year for the industry. Another event held pretty much at the same time was the annual Waterborne Symposium, which is traditionally in New Orleans the week prior to Mardi Gras. The 2010 symposium theme was Advances in Sustainable Coatings Technology – a theme of great importance in today’s envi-
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ronment. Despite the travel impact of severe snowstorms that hindered attendees from the northeast, Waterborne still had nearly 200 attendees, 25 presentations and 28 posters. The technology showcase featured 15 exhibitors. For the first time, the symposium also featured a Composites Matrix Workshop, which attracted 60 people. The Shelby F. Thames Best Paper Award was presented to Edwin P. Chan, Kurt A. Page and Christopher M. Stafford from the Polymers Division, National Institute of Standards and Technology for their paper entitled “Harnessing Surface Wrinkling to Measure the Viscoelastic Properties of Polymer Films and Coatings”. The PCI Outstanding Paper Award was presented to Jung Kwon Oh, Bedri Erdem, Jeff Anderson, Kumar Nanjundiah and Jeff Sweeney, Dow Coatings Materials, Dow Chemical Company for their paper entitled “High Throughput Methods for Developing Low-VOC Waterborne Coatings Derived from Polyurethane Dispersions Based on Natural-Oil Polyols”. In addition, Eastman Chemical Company sponsored the USM Best Graduate and Undergraduate Student Poster Awards. It is gratifying to see support for coatings students. We need to encourage young people to pursue a career in the industry. Likewise I think it wonderful to see this publication continue to support an award at Waterborne. Mark your calendar for next year’s Waterborne Symposium which will be held March 2-4, 2011. And of course the big event is coming up on us quickly – this issue of PCI is the Show issue for the American Coatings Show and Conference, both of which will undoubtedly exceed expectations. Nearly 100 highlevel papers have been selected from the several hundred submitted for the conference program. Sixteen focused sessions will be held during three days, including a new session “Science Today – Coatings Tomorrow”. The response from the exhibitor community has been strong, and pre-registrations are high. This event will definitely surpass the 2008 inaugural ACS. So if you haven’t already done so – make you plans and be sure to attend. You cannot afford to miss this!!
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By Darlene Brezinski, Ph.D. / Editor 7/3/08 11:27:11 AM
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I NDUSTRY NEWS
Global Paint Additives Market to Exceed $6 Billion SAN JOSE, CA – According to a new report by Global Industry Analysts Inc. (GIA), the world market for paint additives is projected to exceed $6.0 billion by the year 2015. The trend towards low- or zero-VOC products and the increasing shift towards water-based paint systems are fueling demand for paint additives, providing tremendous growth potential for suppliers of paint and coating additives. The paint and coatings industry has been put under significant pressure by stringent environmental regulations in recent years. In a bid to minimize the impact of their products on the environment, several manufacturers of coatings began reformulating their products. As a result, demand for novel additives that ensure aid in addressing environmental concerns has increased in recent years. The United States dominates the world paint additives market as the single-larg-
est market. The global economic crisis decelerated growth in value demand of paint additives in the United States. Demand for paint additives is expected to revive in the coming years, owing to increasing demand for these products
EPA Increases Transparency Rules on Chemical Risk WASHINGTON, DC – The U.S. Environmental Protection Agency (EPA) has announced a new policy to increase the public’s access to information on chemicals. EPA has announced its intention to reject a certain type of confidentiality claim, known as Confidential Business Information (CBI), on the identity of chemicals. The chemicals that will be affected by this action are those that are submitted to EPA with studies that show a substantial risk to people’s health and the environment and have been previously disclosed on the Toxic Substances Control Act (TSCA) Chemical Inventory. This action represents another step to use the agency’s authority under the existing TSCA to the fullest extent possible. Under the TSCA, companies may claim a range of sensitive, proprietary information as CBI. Under Section 8(e) of the TSCA, companies that manufacture, process or distribute chemicals are required to immediately provide notice to EPA if they learn that a chemical presents a substantial risk of injury to health or the environment. The Section 8(e) reports are made available on EPA’s website. Until now, companies would routinely claim confidentiality for the actual identity of the chemical covered by the Section 8(e) submission, so the public posting of the information would not include the name of the chemical. The new policy ends this practice for chemicals on the public portion of the TSCA Inventory. For additional information on the new policy, visit www.epa.gov/oppt/tsca8e/.
MPI Approval System to be Adopted in Korea BURNABY, Canada – MPI, the institute that establishes architectural paint standards and quality assurance programs in North America, will partner with the Korea Institute of Con8
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from formulators in an effort to adhere to changing legislation. Growth in the global market for paint additives is primarily originating from emerging markets such as Asia Pacific. The rapid economic growth in most of the emerging countries in recent years resulted in rampant architectural construction and industrial activity, which created significant demand for paint that, in turn, increased demand for paint additives. Owing to continued growth in architectural construction activity in countries such as India and China, Asia Pacific is expected to emerge as the fastest-growing regional market for paint additives worldwide in the coming years. The report, “Paint Additives: A Global Strategic Business Report,” provides a comprehensive review of market trends, competitive scenarios, product introductions and recent industry activity.
struction Materials (KICM) to test paint and coatings to MPI standards. Carboline Korea and KCC already have products approved by MPI, and more Korean paint suppliers are expected to follow. This will enable facility owners and specifiers with assets in Korea and throughout Asia to access locally sourced paint and coatings approved via a well-proven mechanism for verifying their performance. MPI already has a similar testing agreement with the Paint Research Association in the UK for European paint suppliers. With this new agreement, MPI will have global coverage. Seoul-based KICM is the designated agency for testing, inspection and standards for 41 Korean and international organizations. The agency performs construction-materials testing and research to assure the safety of architectural structures.
U.S. Minerals Sector Declined in 2009 RESTON, VA – According to the U.S. Geological Survey’s recently released report, Mineral Commodity Summaries 2010, the value of U.S. mineral production significantly declined in 2009. The value of raw, nonfuel minerals mined in the United States was $57.1 billion in 2009, a decline of 20 percent over the past year. The value of materials domestically processed and refined from these raw minerals was $454 billion in 2009, a 25 percent decline from 2008. Also over the past year, U.S. dependence on foreign sources for minerals has increased, continuing a trend that has been evident for more than 30 years. The United States relied on foreign sources to supply more than 50 percent of domestic consumption of 38 mineral commodities in 2009 and was 100 percent reliant on imports for 19 of those mineral commodities.
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I NDUSTRY NEWS A decline in the U.S. housing market during 2009 caused reductions in the production and consumption of construction materials. Declines in automobile and durable-goods manufacturing resulted in reduced production and consumption of metals including copper, iron, steel, lead and platinum-group metals. The USGS report addresses events, trends and issues in the domestic and international mineral industries and includes statistics on about 90 mineral commodities. It is available at http://minerals.usgs.gov/minerals/pubs/mcs/.
Facility in Boston Harbor. The product, a fast-setting, high-solids epoxy coating, was applied to a gravity thickener at the plant, which is the second-largest watertreatment facility in the United States. The George Campbell Award is given for outstanding achievement in the completion of a difficult or complex industrial commercial coatings project. The Massachusetts Water Resources Authority, owners of the Deer Island plant, and coatings contractor SOEP Painting Corp. of Malden, MA, will receive the award in conjunction with PPG.
SSPC Recognizes PPG With George Campbell Award
PCI Launches Site Dedicated to American Coatings Show
PITTSBURGH – PPG Industries’ Protective and Marine Coatings (PMC) business has been selected as a recipient of The Society for Protective Coatings’ (SSPC) George Campbell Award for 2009-2010. PPG PMC earned the recognition for the performance of its Amerlock 2/400 coating at the Deer Island Water Treatment
TROY, MI – PCI Magazine has introduced a new microsite dedicated to the American Coatings Show. The site, www.pcimag.com/ac_show, includes a schedule of the show, a dining guide for Charlotte, and a blog discussing the latest information about the show. Attendees can get a preview of new products available at the
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show by visiting the microsite’s Online Exhibits. Also available on the microsite is an Exhibitor Info section that gives a list of exhibitors and their booth numbers.
Private U.S. Companies Optimistic About Future SOUTHFIELD, MI – The majority of private U.S. companies are optimistic about the U.S. economy in 2010, according to a global survey of 7,400 private firms in 36 countries. The survey was conducted in November 2009 by Grant Thornton International Ltd. In the United States, private businesses account for an estimated 100 million jobs, more than 70 percent of U.S. employment. In the United States, 51 percent of respondents said that they were optimistic about the U.S. economy in 2010, while 31 percent said they were pessimistic. Globally, 51 percent were optimistic about their respective country’s economy, and 27 percent were pessimistic. The three most optimistic countries were Chile, India and
7/17/08 10:08:44 AM
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I NDUSTRY NEWS Australia; and the three most pessimistic countries were Japan, Spain and Ireland. By a two-to-one margin, U.S. private businesses plan to increase their work force rather than decrease it (29 percent verses 14 percent), while 56 percent will keep it the same. Globally, 34 percent plan
to increase their work force, 14 percent plan to decrease, and 50 percent plan no change. Countries with the greatest planned increases were Vietnam (64 percent), Brazil (63 percent) and India (56 percent); the lowest employment increases were planned in Italy (14 percent), Ireland
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(15 percent), Germany (15 percent) and France (16 percent). In the United States, 51 percent believe that their company’s revenues will rise in the coming year.
ECOAT 2010 Conference Set for May LOUISVILLE, KY – ECOAT 2010 is scheduled to take place May 4-6, 2010, at the Louisville Downtown Marriott, Louisville, KY. The event is an educational conference for people involved in the electrocoat business and for those interested in learning about electrocoating. Three keynote addresses will be offered at the conference. Jeff Oravitz, MetoKote Corp., will kick off the conference with the topic “Manufacturing After the Crisis.” Matt Kirchner, American Finishing Resources LLC, will start day two of the conference by exploring several trends in the U.S. energy sector. For the final keynote of the conference, Steve Schulte, Hixon Inc., will discuss environmental impacts to industrial/electrocoat facilities and practical steps for compliance. Visit www.electrocoat.org/conference for additional information.
Brookfield Offers Training to Maximize Efficiency MIDDLEBORO, MA – Brookfield is offering two courses for users of Brookfield instrumentation. These day-long training sessions give attendees the know-how to verify and improve upon the data required for meaningful research and development and successful quality-control testing. The Practical Course on Viscosity Measurements gives attendees the tools and concepts they need to make the most precise viscosity measurements possible. The course is designed for operators at all levels of experience. The Applied Course on Viscosity Test Methods is designed for the intermediateto-advanced Brookfield instrumentation user in research and development, analytical, and process engineering functions. Focusing on test methods and techniques, it will review and discuss how Brookfield rotational viscometers and rheometers can be used to provide meaningful product analysis. The course takes participants beyond pass/fail criteria, to an understanding of how to apply viscometric data as a problem solving and product performance and processing tool. Visit www.brookfieldengineering.com for course information.
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I NDUSTRY NEWS Brookfield has also introduced a new series of online training videos detailing how to verify calibration of viscometers and rheometers. Visit www.brookfieldengineering.com/support/videos.asp to view the videos.
Nano-Engineering Conference Issues Call for Papers ANCHORAGE, AK – ICCE-18, the 18th International Conference on Composites or Nano Engineering, will take place July 4-10, 2010, in Anchorage, AK. The confer-
ence is accepting new paper titles for presentation. Interested authors should submit detailed two-page short papers to David Hui at
[email protected]. The conference is looking for new topics in pure and applied science and engineering. All short papers will be reviewed and published as short papers in World Journal of Engineering.
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HOPEWELL JUNCTION, NY – A call for papers has been issued for the 12th International Symposium on Particles on Surfaces: Detection, Adhesion and Removal. The conference will be held in conjunction with the Process Cleaning Expo in Louisville, KY, on May 4-6, 2010. For more information about submitting a paper for the symposium, contact Robert H. Lacombe, Symposium Chairman, at
[email protected].
Deacom Announces ERP Training Schedule WAYNE, PA –The 2010 course schedule for DEACOM® University is now available at www.deacom.net. The schedule will include new course additions, including DEACOM Contact Management. DEACOM University is an accredited ERP training program dedicated to educating users in all areas of the DEACOM Integrated Accounting and Enterprise Resource Planning (ERP) Software System.
Cal Poly Offers Polymers and Coatings Short Course SAN LUIS OBISPO, CA – The Polymers and Coatings program at California Polytechnic State University, San Luis Obispo, CA, will offer a Polymers and Coatings Introductory Short Course during the week of July 19-23, 2010. The one-week course will cover many aspects of coating technology, including resin chemistry, pigments and fillers, additives, VOC testing, application aspects, and rheology. For additional information, visit ww.polymerscoatings.calpoly.edu.
ASTM Offers Online Training WASHINGTON, DC – ASTM International is offering a series of free, one-hour online training workshops that are designed to assist ASTM members. Sessions include Balloting and Handling Negative Votes, Developing and Revising a Standard, Work Item Collaboration Area Training, ASTM Online Training and New Member Orientation. For information, visit www. astm.org/MEMBER_TRAINING/. 䡲
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C ALENDAR Meetings, Shows and Educational Programs APRIL 6 Ci4000/Ci5000 Weather-Ometer Workshop www.atlas-mts.com 7 Fundamentals of Weathering Level I www.atlas-mts.com 8 Fundamentals of Weathering Level II www.atlas-mts.com 8-10 CISILE 2010 www.cisile.com.cn/en
18-20 ASC Spring Convention www.ascouncil.org
4-6 ELECTROCOAT 2010 www.electrocoat.org
20-22 Emulsion Polymerization and Waterborne Coatings www.emich.edu/cri
4-6 Particles on Surfaces: Detection, Adhesion and Removal www.mstconf.com
20-22 Logichem 2010 www.logichemeurope.com 30 Understanding Coating Raw Materials www.emich.edu/cri
MAY 4 PSCT May Technical Symposium 12-15 www.psct.org American Coatings Show & Conference www.american-coatings-show.com 4-5 Coatings, Inks and Solvents Technical Advisory Panel 13-16 Meeting PaintExpo
[email protected] www.paintexpo.de
5-6 Basics of Polyurethane Coatings www.emich.edu/cri 12-14 NW Coatings Fest 2010 www.pnwsct.whomedia.com/ symposium-ncf 17-21 Introduction to Paint Formulation http://coatings.mst.edu/index.html 18-19 Sink or Swim 2010 www.clevelandcoatingssociety.org 18-20 Appalachian Underground Corrosion Short Course www.aucsc.com
18-20 Advanced Topics in Polymers and Coatings www.emich.edu/cri 19-21 Spray Finishing Technology Workshop www.owens.edu/workforce_cs/ spray2010.pdf 23-26 RadTech UV& EB Technology Expo & Conference 2010 www.radtech2010.com
JUNE 2-4 Principles and Practices of Coating Formulations www.emich.edu/cri 8-10 Improving Durability and Performance of Coatings www.emich.edu/cri
Providing quality products and excellent customer service for 35 years. PRINCIPALS: 3V, Inc. American Talc Company CINIC America Columbian Chemicals Columbia River Carbonates C R Minerals Dianal America Dover Chemical Durez Corporation Elementis Specialties Fawcett Company Frank B. Ross Fuji Silysia Hexion Specialty Chemicals, Inc.
Imerys Instrumental Polymers Technology Kronos LCP Technology Nuroz, LLC Perstorp Reichhold Chemicals Rockwood Pigments Specialty Polymers Taminco TOR Minerals Toyo Ink America Troy Corporation Vitro Minerals Wayne Pigment World Minerals
TCR Industries markets specialty chemicals to manufacturers of coatings, adhesives, inks, sealants, caulks, plastics, building products and allied industries. Our Fine Chemicals Division markets specialty chemicals to manufacturers of food products, cosmetics and personal care products. Our sales geographical territory includes 11 western states and Baja California, serving out of seven warehouses. TCR is practicing "Responsible Distribution" as a proud member of the National Association of Chemical Distributors.
26 Centerpointe Drive La Palma, California 90623 Toll Free: (877)827-1444 www.tcrindustries.com
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C O M PA NY NEWS
Kelly-Moore Receives Green Business Award SAN CARLOS, CA – Kelly-Moore Paint Co. Inc., San Carlos, CA, has received the Green Large Business of the Year award. The company outperformed 100,000 California companies to win the award. Kelly-Moore was selected for its series of recycling programs that diverted 60 percent of its waste and for its ability to motivate employees to commit to recycling efforts. Kelly-Moore was also recognized for its carbon offset program, which resulted in its San Carlos plant being carbon neutral. In 1995, the company developed a safer, more environmentally responsible technique to dispose of leftover paint and became the first paint company in the industry to collect and remanufacture a recycled paint, eCoat. Previously, when half-
used paint cans were returned, the paint and cans were considered unrecyclable waste. Now, Kelly-Moore uses a system that removes the labels and residue from the cans, making them recyclable. The returned paint is sorted by color and type and remanufactured into eCoat. In April 2009, Kelly-Moore started a program to recycle Super Sack storage bags, cut-up plastic totes and other
AkzoNobel Invests in UK Research Hub AMSTERDAM, The Netherlands – AkzoNobel is investing almost €10 million to enhance its Felling, UK, site. A fire-protection testing laboratory and a polymer lab for powder coatings are being added to the existing R&D infrastructure at the site. Due to be completed early next year, the testing lab will be used by the company’s Marine & Protective Coatings (M&PC) business to develop fire-protection coatings. The new polymer lab will allow researchers at AkzoNobel Powder Coatings to handle and develop new materials; it will also include scale-up capability and an application line.
Huntsman Amines Bridge Gap in Chinese Rail Project EVERBERG, Belgium – A series of concrete bridges that support a new high-speed rail line connecting Beijing and Shanghai is set to benefit from the protective properties of specialty polyetheramines from the Performance Products division of Huntsman Corp. The Chinese Ministry of Railways is building an 800-mile dedicated passenger rail link to ease pressure on one of China’s busiest transport routes. The route crosses the Yellow River and the Yangtze delta. Because of the soft terrain in this area and the need to minimize land usage, almost 80 percent of the line is being built on metal and concrete bridges that are compatible with the transportation system already in place. It is on these structures that Huntsman’s polyetheramines will be used. JEFFAMINE® D-2000, JEFFAMINE T-5000 and JEFFAMINE D-400 polyetheramines have been used to create a polyureabased coating that is being sprayed onto the bridges’ concrete 18
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previously unrecyclable containers. The program resulted in a 10-15 percent reduction in landfill waste. Additionally, Kelly-Moore’s factory management developed a collection system for rainwater to offset water usage and built a berm around the manufacturing plant to prevent any possible paint spillage from getting into the local creek. Kelly-Moore has continued to green its manufacturing facility. It has replaced old HVAC units with energy-efficient ones, installed a new dust collector that reduced plant noise levels and energy consumption by approximately 50 percent, enrolled in a program to buy carbon offsets, and captured waste heat generated from the plant’s large compressor and now uses it to heat an adjacent building.
slabs, which act as a hardwearing base for the ballast-less tracks. Forming a waterproof protective layer, the coating will guard the concrete against weather, abrasion, and general wear and tear.
Columbian Chemicals Expands TCR Industries’ Territory LA PALMA, CA – Columbian Chemicals, Marietta, GA, has expanded TCR Industries’ territory to represent Columbian’s Raven® industrial carbon blacks. The expanded territory covers 11 western states through seven warehouses. The territory includes California, Oregon, Washington, Idaho, Montana, Wyoming, Utah, Nevada, Colorado, New Mexico and Arizona. TCR Industries is authorized to promote Columbian carbon black products in the paint and coatings, inks, plastic, and construction markets.
Daimler Chooses GREENKOTE Coating Process CLEVELAND – GREENKOTE® Plc, a global coating technology company headquartered in Cleveland, will provide corrosion protection for selected Daimler automotive parts beginning in the first half of 2010. Initial orders include components for passengersafety-related applications. Additionally, Daimler is finalizing technical approval of GREENKOTE as one of its suppliers of zinc diffusion coatings, using the company’s patented thermo-diffusion coating process. GREENKOTE is a thermal-diffusion coatings process that modifies and improves the basic surface characteristics of metals and is applicable to metal finished parts in many industries.
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C O M PA NY NEWS AkzoNobel Powder Coatings to Supply Ingersoll Rand
Malvern Instruments Opens Center of Excellence in India
MONHEIM, Germany – Cognis has announced recipients of its internal Innovation Award. The award recognizes teams responsible for innovative and successful projects. The Gold Award went to a team from the Functional Products strategic business unit (SBU) for Emgard FE, a fuel-efficient axle lubricant for heavy-duty trucks. The Silver and Bronze Awards went to two teams from the Care Chemicals SBU. Silver was given to the employees behind Plantapon LGC Sorb, a new environmen-
MALVERN, UK – Malvern Instruments has opened a third center of excellence in India, established through its joint-venture company Malvern Aimil Instruments Pty. Located in Delhi and designed to serve customers in the north and northeast of India, the new center of excellence houses laboratories that are equipped with a range of Malvern systems and staffed by a full-time applications team. The team will provide demonstrations and deliver training, applications and technical support, as well as sample analysis.
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Cognis Recognizes Innovative Employees
AMSTERDAM, the Netherlands – AkzoNobel Powder Coatings has entered into a three-year agreement with Ingersoll Rand that makes it the preferred global supplier for powder coatings. AkzoNobel will supply powder coatings to Ingersoll Rand through its brand, Interpon Every Color Is Green.
tally sound anionic surfactant based on alkyl polyglycosides technology. Bronze went to the developers of a customized Euperlan pearlizer concentrate. Finally, the Special Category Award, which was presented for the first time this year, was won by a team that implemented a package of measures to improve the ether sulfate production process.
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Hockmeyer Equipment Granted Fifth Patent HARRISON, NJ – Hockmeyer Equipment’s fifth patent covering immersion mill enhancement has been granted by the U.S. government. The patent covers the deterrence of wear at a bearing construct in a basket media mill. The device involves the introduction of slots in the rotating peg hub within the basket. As the hub rotates, centrifugal force pulls the media and feedstock away from the polymer-bearing construct within the peg hub. This creates two favorable conditions. One result is extended bearing life regardless of the media type or size; the other is the elimination of micro media escaping through the clearance between the rotating drive shaft and the bearing construct. Bearing life, typically six months to one and a half years, has more than doubled.
BASF Expands Superior Materials’ Distribution Agreement GARDEN CITY, NY – BASF Corp. has announced an expansion of Superior Materials Inc.’s distribution responsibilities. For customers in the plastics industry, Superior Materials Inc. will now be responsible for sales of BASF’s pigments, colorants, dyes and additives portfolio in New York, New Jersey and Connecticut. For customers in the coatings, sealants, adhesives, elastomers and ink industries, Superior Materials Inc. will be responsible for sales of pigments, colorants, dyes, dispersions and Uvinyls® in New York, New Jersey, Connecticut, Maryland, Delaware, Washington D.C. and Pennsylvania east of Harrisburg. Superior Materials Inc. will also be responsible for sales of Attapulgite additives in New York, New Jersey, Connecticut, Pennsylvania, Virginia, West Virginia, Maryland, Delaware and Washington D.C.
Nevada DOT Approves Seicoat Corp. Coatings LOS ANGELES – A line of anti-graffiti coatings from Seicoat Corp. has recently been approved and added to the Qualified Products List by the Nevada Department of Transportation. The products are GPA-200 Graffiti Proofer ® Anti-Stick and GPA-300 Graffiti Proofer Non-Stick anti-graffiti coatings. The GPA-200 coating is extremely durable and causes most paints to simply run off the film. The GPA-300 product
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allows anyone to remove graffiti with a dry cloth or water rinse without the use of any cleaning chemicals. The coatings are clear, UV stable, chemical and abrasion resistant, and provide true non-stick surfaces that resist paint, permanent markers, stickers and adhesives.
Siltech Acquires Rhodia Manufacturing Facility TORONTO – Siltech Corp. has acquired Rhodia’s manufacturing facility in Mississauga, Ontario, Canada. The 113,000-square-foot plant is equipped with highly specialized chemical reactors, bulk storage and railroad facilities. Siltech will retain Rhodia’s employees and will continue to manufacture Rhodia’s products under a long-term contract. Siltech’s present manufacturing and research facility in Toronto, Canada, will continue to operate as the company’s headquarters.
Hexion Specialty Chemicals Plans Monomer Plant in Korea COLUMBUS, OH – Hexion Specialty Chemicals Inc. has approved construction of a manufacturing plant in Onsan, Korea, to produce Cardura™ monomer, a glycidyl ester derivative of Versatic Acid 10. The plant will be constructed within an existing Hexion manufacturing complex in Onsan. Construction of the new facility will begin in the first quarter, and completion is slated before the end of this year.
Bring on all your bright ideas. Our global UV/EB resources help make them winners. Wherever you need UV/EB support, Sartomer is there for you – in the Americas, Europe, and Asia. We deliver leading-edge UV/EB technology and responsive local manufacturing. We can also help with the complexities of product/country registration issues. Our in-depth expertise and high-performance specialty chemicals will help you bring all your ideas to life and get them to market – fast. Now you can take on any job – plastic and metal coatings, inks, display, automotive, adhesives – or even a totally new application. Rely on us from initial concept to final delivery.
Hexion to Sell Solventborne Coating Resins Business COLUMBUS, OH – Hexion Specialty Chemicals Inc. has signed a definitive agreement to sell its Italian solventborne alkyd and polyester coating resins business to an affiliate of Tenax Group, an Italian-based company that produces similar products. The sale will include all aspects of the business, including a production facility in Cola di Lazise, Italy. The sale represents Hexion’s exit from the European solventborne coatings market. Hexion continues to fully participate in the waterborne, powder coatings and coating resins markets, both in Europe and globally.
Formulators choose Sartomer for UV/EB innovation and consistent quality… batch after batch. Our broad line of more than 500 monomers and oligomers leads the world. If your formulation calls for something unique, we tailor a custom fit. Contact us now for the help you want to beat the competition. Call 800-SARTOMER, 610-363-4100 or visit www.sartomer.com.
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Baltimore, MD; May 24-26, Booth 309
Eastman Acquires Specialty Polymers Facility in China KINGSPORT, TN – Eastman Chemical Co. has completed the acquisition of Tongxiang Xinglong Fine Chemical Co. Ltd., a cellulose-based specialty polymers manufacturing facility located near Shang-
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C O M PA NY NEWS hai, China. The acquisition will support Eastman’s Coatings, Adhesives, Specialty Polymers and Inks segment, specifically its Ensure™ product line, by providing additional capacity to meet the growing demand in China.
Arkema Integrates Acrylics Assets From Dow CARY, NC – Arkema has formally completed its acquisition of Dow’s Acrylic Monomers and Acrylic Latex Polymers (UCAR Emulsion Systems) business in North America.
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The acrylic monomers production site in Clear Lake, TX, is being integrated into Arkema’s existing Acrylics business unit, within the Industrial Chemicals business segment. The acrylic latex polymers activity forms a new business unit, Arkema Emulsion Systems, which is dedicated to the paint, coatings, adhesives and construction-product markets. This new business unit will be part of the Industrial Chemicals business segment. Richard Jenkins has been appointed President of this newly created business unit. Jenkins was previously the General Manager of Dow’s UCAR Emulsions Systems and Monomers business. Arkema Emulsion Systems is headquartered in Cary, NC, and operates three latex production facilities in California, Illinois and Louisiana. Research and development, marketing, sales and administration functions are located at the North Carolina headquarters. The Polyphobe™ rheology modifiers formerly in the UCAR Emulsion Systems product line are being integrated into Arkema’s Coatex subsidiary. The integration will extend Coatex’s portfolio for the paint and coatings industry to the United States, Canada, Mexico and Puerto Rico markets.
BASF Venture Capital Invests in Quantiam Technologies LUDWIGSHAFEN, Germany – BASF Venture Capital GmbH, Ludwigshafen, Germany, is investing in Quantiam Technologies Inc., Edmonton, Canada. Quantiam Technologies develops and markets functional coatings for extreme operating environments such as petrochemicals industry applications. Quantiam will use the additional capital to fund further growth. A major focus of the investment will be catalytic surface coatings known as catalyzed-assisted manufacture of olefins or CAMOL.
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LUXEMBOURG – The Flint Group has signed an agreement to acquire Torda, a manufacturer of printing inks for the packaging markets in northern Europe, the Balkans and the Middle East, with a substantial presence in Eastern Europe. This acquisition is the third step Flint Group has taken within the last 12 months to foster its expansion in Eastern European markets. 䡲
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N AMES IN THE NEWS 䡲 Patrice Barthelmes has been appointed CEO of Eliokem, a worldwide specialty chemical company. Barthelmes served as Vice President and Director for the Packaging & Building Materials division of Rohm & Haas, a position he held from 1999 until 2009, when Dow purchased Rohm & Haas. In 2009, he was appointed Vice President and Group Director for Dow’s AdheBarthelmes sives & Functional Polymers division. 䡲 Kristopher Felice has joined CAS-MI as a Chemist/Coatings Technologist. In his new role, Felice uses a wide range of analytical techniques, such as SEM/EDXA, FTIR, ATR, Microscopic FTIR and MDSC. He also has expertise in paint and coatings physical testing, as well as failure analysis.
䡲 Scott Harris has been promoted to the position of Operations Manager at Thermcraft Inc. Harris has over 25 years of manufacturing experience. 䡲 Jeff Hartel
has joined NSL Analytical Services Inc. as Account Manager for metallurgical and mechanical testing. Hartel will assist with business development activities. He will also introduce NSL’s elemental chemical analysis capabilities to metallurgical and mechanical testing customers.
䡲 NanoHorizons Inc. has appointed Chris Haupt to the newly created position of Vice President, Industrial Business Unit. Haupt’s professional focus and expertise are in polymer chemistry and business development for the C.A.S.E and flexible-foam markets. 䡲 Timothy M. Knavish has been appointed Vice President, Automotive Coatings, Americas, for PPG Industries. He will report directly to Cynthia A. Niekamp, Vice President, Automotive Coatings. 䡲 Malvern Instruments
has appointed Terry Liu to the role of Process Specialist. Liu is part of the Malvern China team and works from the company’s Shanghai office. He will support customers across a range of industries in their implementation of Insitec in-, on- and at-line solutions for particle-size measurement and process optimization.
Liu
䡲 Joan A. Schuller has been named General Manager for the North
American region of Dow Coating Materials. In her role, Schuller is responsible for setting the business strategy and leading the North American Leadership Team.
䡲 H. Morgan Smith has been named the Chairman of the Board of
Van Horn, Metz & Co. Inc. Barrett C. Fisher III has assumed the role of President, and Brian Boorman has been named the Executive Vice President.
䡲 Superior Materials Inc. has hired Peter Zillitto as Regional
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Sales Manager, Mid-Atlantic. Zillitto will be responsible for the sale of BASF pigments, colorants, additives and Attagel® products in eastern Pennsylvania, Maryland and Delaware, along with Attagel in all of Pennsylvania, Virginia and West Virginia. He will also sell Imerys, Evonik, Akzo Nobel, Kronos, DayGlo and Schlenk products. 䡲
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Nanocomposite for High-Performance Fabrics
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nflatable fabrics are used in a number of different applications, such as automotive airbags, parachutes, rafts, hot air balloons and inflatable structures for space exploration. An inflatable fabric consists of a base fabric that provides strength and a multifunctional coating layer. Besides blocking pores in the fabric and providing impermeability, the coating imparts flexibility, toughness and tear strength to the fabric. In addition, the coating protects the fabric from the heat generated during inflation and provides smooth deployment. A desirable coating material should have low permeability, good adhesion to the fabric and good mechanical strength. The first generation of inflatable fabrics was based on nylon 6,6 fabric with a neoprene coating. However, neoprene had several shortcomings, including necessarily thick coatings, a tendency to stick when deployed, limited environmental stability and marginal thermal resistance. As improvements in nylon 6,6 and alternative fabrics continue, silicone coatings are being used more often than neoprene coatings to: (a) protect the fabric from heat-scorching; (b) allow thinner and more foldable coated fabrics; (c) improve long-term environmental stability; and (d) provide better compatibility with nylon. Silicone coatings are increasingly used on inflatable fabrics in several consumer, military and space applications. An excellent example is the successful deployment of the airbag system for the Mars Pathfinder. Silicone coatings exhibit one to two orders of magnitude less atomic oxygen erosion compared to their organic counterparts in low earth orbit.1 Notwithstanding their excellent long-term thermal stability, weatherability and flexibility, silicone coatings are relatively weak compared to other elastomers. Fillers, such as amorphous silica, are often added to the matrix to reinforce the network. Another drawback of silicone material is its poor adhesion to the substrates because of its low surface energy. These problems can be addressed by nanotechnology, and indeed various attempts have been made using nanoscale additives to strengthen the silicone and reduce gas permeability. This article introduces a commercially viable nanoscale additive developed by NEI Corporation that improves fabric tear strength, tensile strength and hardness at low additive loadings. At the same time, the NEI product greatly improves adhesion between the silicone and the fabric. The NEI product is a nanoscale additive package that is easily added to commercial silicone coating formulations to impart excellent coating properties. The first part of this article discusses how nanoscale additives can be used to improve the properties of the sili-
cone base polymer. The second part presents data on NEI’s nanoscale additive-reinforced silicone-coated fabric.
Forming Silicone Nanocomposites In recent years, polymer nanocomposites have received significant attention since nanoscale particles provide an opportunity for enhancing the mechanical and functional properties of the polymer at relatively low-volume fractions, thereby preserving the desirable properties of the polymer, such as flexibility and ductility. The reasons for using nanoscale particles in a polymer matrix are outlined in the following points. 1. Incorporating nanoscale particles, particularly those with a high aspect ratio (e.g., platelet-shaped clay nanoparticles) in a polymer matrix leads to several beneficial features, including low percolation threshold (< 2 vol%), high interfacial area and a size scale that is comparable to that of polymeric molecules. 2. The interface between surface-modified nanoparticles and the polymer matrix will be smooth, resulting in effective load transfer to the matrix and a smooth surface finish to the final nanocomposite. Conversely, coarse particles, because of their large size and particularly when added in large volume fractions, do not bond well with the polymer matrix. Consequently, coarse particles degrade the mechanical properties of the base polymer. 3. Incorporating solid particles (or nanoparticles) in a polymer matrix or in a polymer-based coating formulation can give rise to processing issues such as a significant change in viscosity, inhomogeneous mixing and reduction of shelf life. All these problems can degrade the final properties of the nanocomposite. Nanoparticles present less of a problem than micon-sized particles because nanoparticles can be added in much smaller quantities to achieve a similar reinforcing effect. Additionally, when nanoparticles are modified with a suitable organic molecule/oligomer, they become compatible with the matrix and ameliorate processing problems. Silicones, also referred to as polysiloxanes or PDMS, have the repeating unit [Si(R)2-O]- and are prepared from chlorosilanes. Depending upon the number of repeating units in a polymer chain and the degree of crosslinking, several different types of commercial silicone products can be produced: fluids, emulsions, compounds, lubricants, resins and elastomers or rubbers. The silicone material discussed in this article is a silicone elastomer, suitable for use as an inflatable fabric coating. Nanoscale additives in silicone coatings offer the opportunity to improve physical gas barrier properties, in addition to enhancing mechanical properties. Some data indicates that oxygen transmission rates for nanocompos-
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Coatings ites of silicone are usually less than half that of the unmodified polymers. The aspect ratio of the additive nanoparticles has been shown to have a major effect on enhancing gaseous barrier properties, particularly with higher aspect ratios.2 Researchers at Argonne National Laboratory demonstrated that the oxygen barrier properties of nanocomposite films were 200,000 times better than oriented propylene and over 2,000 times better than Nylon-6.3 Researchers at NASA showed that by adding about 2 vol% additives in a thermoplastic matrix, the hydrogen permeability can be reduced by 10 to 20%.4
Experimental Procedures An example of the wide variety of airbag applications is the Mars Pathfinder airbag system. With funding provided by NASA, we chose to work with materials similar to those used for this Mars mission. Dow Corning Liquid Silicone Rubber (LSR 3730) was used as the base silicone material. It is a two-component, fumed silica-filled, high solids (>98%) vinyl-addition (platinum catalyzed), hightemperature-curing (150-200 °C) silicone with high viscosity (165,000 cSt). This is a commercial coating formulation optimized for adhesion to fabrics and is chemically similar to the silicone rubber used to coat the Mars Pathfinder airbags (i.e., Silastic LT-50, a Dow Corning product designed for enhanced low temperature performance). The fabric used was Vectran, a commercial woven fabric obtained from Fabric Development, Inc. NEI nanoscale additives, hereafter called Nanomyte™ PC-30, were prepared by modifying the surface of inorganic nanoparticles with organic functional groups that can react with the silicone matrix, thereby facilitating dispersion and allowing chemical bonding of the nanoparticles with the matrix. The functional groups also improve the adhesion of the silicone coating with the fabric. Nanomyte PC-30 was mixed thoroughly with part B of LSR 3730 before mixing with part A and catalyst. The mixed, uncured silicone resin was then applied to Vectran fabric and cured at 190 °C, followed by aging at 120 °C. This coating and curing process was then repeated to apply a second coat. Coated Vectran sheets were cut to the standard geometry as specified in MIL-C-21189(Aer) TM 10.2.4 for cutslit tear testing. Samples were tested on a CRE-type tensile machine using hydraulic/pneumatic grips. Peel testing was conducted according to ASTM D 187601, Standard Test Method for Peel Resistance of Adhesives (T-Peel Test) using an MTS QTest/25 Elite Controller frame
fitted with a 5kN load cell and rubber-faced, manual grips. To prepare T-Peel test samples, uncured coating material was applied to the coated faces of two cured, coated Vectran sheets using a drawdown process. The sheets were then laid face-to-face to make sandwiched sheets, which were compressed together and cured. Spherical test articles, 18” in diameter, were fabricated at ILC Dover (a leading manufacturer of high-performance softgoods, and a collaborator on this project) for leakage testing (Figure 1). The test articles were inflated to 1, 2 and 3 psi, and the leak rate was measured. This was followed by holding the inflation pressure at 5 psi, then reducing the pressure and repeating the leakage tests at 3, 2, and 1 psi.
Nanoscale additives in silicone coatings offer the opportunity to improve physical gas barrier properties, in addition to enhancing mechanical properties. FIGURE 1 | Pressurization testing of 18” test spheres at ILC Dover.
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Nanocomposite Coatings for High-Performance Fabrics
Results and Discussion Figure 2 shows the results from cut-slit tear testing. The coated fabric containing Nanomyte PC-30 exhibits significantly improved tear strength. Examination of the tested samples revealed that different degrees of delamination of the silicone coating material from the fabric had occurred as a result of the tearing action (Figure 3). In general, there appeared to be substantial delamination of coating material from the Vectran for control samples, especially at the grip points and along tears. This delamination is an adhesive failure. The samples containing Nanomyte PC-30 exhibited minimal or no delamination. Further, in some cases, residual coating material remained connected to exposed yarns within the tear zone giving a “toothed”
appearance, offering evidence of a cohesive failure; this was not observed to such a degree for control samples, where yarns were typically stripped bare. The above tests demonstrate the importance of adhesion between the fabric and coating, which is promoted by Nanomyte PC-30. Further evidence of stronger adhesion is shown by the T-Peel test. Figure 4 shows a strong correlation between Nanomyte PC-30 loading and adhesive strength. In addition to enhancing coating-fabric adhesion and mechanical strength, Nanomyte PC-30 greatly suppresses leakage in fully sealed test articles. Figure 5 shows a strong trend towards reduced test article leakage for spheres manufactured with the nanocomposite material versus control.
FIGURE 2 | Averaged tearing strength of coated fabric with and without 1.5 wt% Nanomyte PC-30.
FIGURE 4 | Averaged peel resistance data for self-adhesion of coating formulations. 45 40
650
35 Peel Resistance (N)
Average Tearing Strength (lbs)
700
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30 25 20 15 10
450
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FIGURE 3 | Macro photograph of cut-slit tear samples along the tear.
FIGURE 5 | Graph of leak rate during pressure testing of optimally sealed test articles. 400
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Coated Yarns
Bare Yarns
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Nanocomposite Coatings for High-Performance Fabrics
…the mechanical strength and coating-fabric adhesion can be significantly enhanced by adding relatively low levels of nanoparticles. Conclusions We have shown that the mechanical strength and coating-fabric adhesion can be significantly enhanced by adding relatively low levels of nanoparticles. Certain fabric coatings that are used for space applications are formulated with fillers, including metal oxide particles, in order to increase strength. However, these additives typically require high additive loading in order to attain the desired properties, which can adversely impact the weight of the part and potentially result in degradation of mechanical properties. Our approach permits the use of far lower levels of additive loading, which better preserves the material’s desirable characteristics. Further, NEI’s nanoscale additives significantly suppress air leakage in
the test articles fabricated. Most importantly, NEI’s technology has a minimal impact on the coating application process. That is, NEI’s patent-pending technology can be readily incorporated into commercially available coating formulations and requires no special processing or equipment when applied to the fabric. In addition, using the NEI nanoparticle additive approach, other desirable functionalities can be engineered into the coating formulation. 䡲
Acknowledgments NEI Corporation is grateful to the NASA SBIR program for funding this Phase II effort, which was carried out under contract NNL07AA11C. The authors wish to thank Ms. Robin C. Hardy of NASA Langley Research Center, Virginia, for her constant encouragement and suggestions during the Phase II program. The authors also wish to thank Ms. Jody Ware of ILC Dover for her support of this development work, particularly with respect to prototype airbag fabrication and testing.
References 1 2 3 4
Dworak, P; Soucek, M. D. Progress in Organic Coatings 2003, 47, 448. Takeuchi, H.; Cohen, C. Macromolecules 1999, 32, 6792. http ://w w w.anl.gov/techtransfer/pd f/Nanocomposite4-7-03.pdf. www.grc.nasa.gov/www/RT2001/5000/5150campbell.html.
For more information see www.neicorporation.com or email
[email protected].
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The World Marketplace for Protective Coatings –
T
he past 35 years have brought massive changes to the protective coatings industry. Increasing levels of regulatory oversight and the reduction in VOC emissions are among the more obvious impacts. The industry also faced a shift in markets, as China, Dubai and other world areas made significant investments in infrastructure to support economic development. However, change is also a reaction to the global trends occurring throughout the world: population growth, globalization/urbanization, climate change/global warming, the healthcare revolution and accelerated technology changes. All of these trends have and will continue to create new opportunities. How can our business model recognize and take advantage of these trends that create coatings opportunities?
Sowing the Seeds of Change: 1970s – 1990s Evolving Regulations In the 1970s, heightened environmental awareness galvanized organizations and individuals into action, culminating in unprecedented changes for the protective coatings industry. The first truly game-changing seeds of change were sown with the Consumer Product Safety Commission’s 1978 ban of lead-based paint in the United States. This caused a ripple effect that increased the scrutiny of the use of lead-based paint in other countries. To fully appreciate the impact, it’s important to remember that lead-based paint (oil alkyds) had been used as a universal coating for a thousand years, and was a dominant
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coating for bridges, ships, infrastructure and other industrial – not to mention consumer – applications in industrialized nations. Soon thereafter, the industry faced another major challenge: sweeping regulations focused on lowering volatile organic compounds (VOCs). Space does not permit a detailed discussion into the regulatory environment taking place during this time. However, it is possible to briefly summarize some of the key milestones. In the 1980s, some countries in Europe had adopted VOC rules that limited the VOC content of certain paint products.1 By 1990 a number of air quality districts, such as SCAQMD (South Coast Air Quality Management District), were regulating Architectural and Industrial Maintenance (AIM) coatings. Additionally, under the 1990 Clean Air Act Amendments (CAAA), the EPA established the Ozone Transport Commission (OTC) to tackle the issue of ozone drifting from one state’s airspace into another’s. And, in 1998, the EPA issued a national rule for VOCs, “National Volatile Organic Compound Emission Standards for Consumer and Commercial Products,” restricting VOC content in most industrial maintenance and marine antifouling coatings to 450 g/L (a limit that is actually above restrictions in some states and districts).2 Lowering VOCs effectively eliminated the use of chlorinated rubbers and vinyls – both of which were extensively used in infrastructure applications. These changing regulations resulted in a technology shift from low-performance systems to high-performance systems, to waterborne systems. Looking back, it is not an exaggeration to say that these technology changes represented a turning point for the industry.
Global Shift Around the same time the protective coatings industry was facing shifting regulations, another shift was occurring that would also have a significant and lasting impact on the industry: the acceleration of infrastructure/economic development beyond the Western world. One such growing market at the time was China, where the economic reform that began in 1978 brought great changes in many areas of Chinese economy, including
By Dr. Karsten Danielmeier, Vice President of Business Development, Coatings, Adhesives & Specialties | Bayer MaterialScience LLC, Pittsburgh, PA APRIL APR IL 2010 | W W W . P C I M A G . C O M
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The World Marketplace for Protective Coatings – Opportunities and Trends
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infrastructure development.3 Another growth area was new opportunities, particularly within the context of five Dubai in the United Arab Emirates, which saw economic global megatrends: population growth, globalization/ growth in the 1970s due to revenues from oil and trade. urbanization, climate change/global warming, healthThis growth was further strengthened by the establishcare revolution and accelerated technology changes. ment of Jebel Ali port in 1979, followed by JAFZA (Jebel Population Growth Ali Free Zone), which was built around the port in 1985, As of November 6, 2009, the U.S. Census Bureau estienabling customers to take full advantage of the port’s mated the world’s population to be 6.795 billion.5 While ISO-certified container and general cargo operations.4 Another event that forever changed the global ecothe overall rate of growth is slowing (Figure 1), the nomic landscape was the fall of the Berlin population gains continue to severely tax Wall in 1989. This event, which to many natural resources, making food and water symbolizes the end of the Cold War, was not increasingly scarce. One viable option for only a social revolution, but an economic conserving drinking water is pipeline modrevolution as well, essentially creating new ernization, which minimizes the loss of markets with which the Western world water caused by leakage. This presents could do business. a tremendous opportunity – as well as The significance of this global shift is a challenge – to the protective coatings twofold. First, it created a global market for industry. Additional areas where protechigh-performance coatings products and tive coatings can be utilized to support the technologies needed as these geographic population boom include housing, as well areas built out their infrastructure to help as the construction and repair of the transsupport economic development. Second, it portation infrastructure, among others. also continued the march toward a truly Globalization/Urbanization global economy. This impacted coatings To many, the Burj Al Arab luxury Globalization increases wealth and the manufacturers who needed to ensure their hotel symbolizes Dubai’s urban demand for mobility and communications, products were in compliance with varying transformation. particularly in emerging areas, such as regulations in the different markets. At APAC (Asia and Pacific) and BRICM (Brazil, Russia, India, the same time, it created the opportunity for manufacChina and Mexico). In fact, much has been written about turers to establish facilities in what had until this time how the five BRICM economies will surpass the current been largely untapped markets, translating into improved major economic powers in the decades to come. This is economies of scale, as well as greater manufacturing and a prospect that must be considered for protective coatdistribution efficiencies. ings manufacturers and their suppliers, who may seize Today and Tomorrow: the opportunities these areas offer, and therefore shift Seeds of Change Grow, Blossom the geographic location of their current manufacturing It is with this backdrop of the last 35 years or so in mind operations to be better able to serve these burgeoning that we turn our attention to the protective coatings economies going forward. industry today … and look toward tomorrow. ProductivIn terms of urbanization, significant investments in ity, sustainability and quality are the key drivers in the mass transportation, as well as infrastructure construccoatings industry today. As such, they are both central tion and maintenance, present opportunities for protecand essential to how the industry operates and seizes tive coatings products and technologies, as well. The numbers are, in fact, staggering. A recent report by CIBC World Markets in Toronto predicts that global spending FIGURE 1 | World population: 1950-2050. on infrastructure could reach $25 -$30 trillion over the 10 next two decades. Of this, the United States will account 9 for roughly $150 billion a year in new infrastructure 9 Billion 8 investment; Europe will require roughly $300 billion a 8 Billion year; China, at least $400 billion a year. The report also 7 states that approximately 40 percent of this money will go 6 7 Billion to transport and nearly one-third to power facilities.6 6 Billion 5 Certain countries within such geographic areas 5 Billion 4 as Africa are looking to build new infrastructure to 4 Billion 3 improve not only their economy, but also the health 3 Billion and well being of its people. In an address given Feb. 2, 2 2009, UN Secretary-General Ban Ki-moon stated: “… 1 infrastructural development is key to economic growth 0 and social progress. Africa needs good roads, schools and hospitals; as well as reliable and efficient water services, electricity grids and telecom networks; while Year information and communication technologies must also be a bigger part of Africa’s future. These remain the Source: U.S. Census Bureau, International Data Base, June 2009 Update. APRIL 2010 | W W W . P C I M A G . C O M
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The World Marketplace for Protective Coatings – Opportunities and Trends
building blocks for job creation and the ability to compete in global markets.”7 The United States, on the other hand, is investing significant resources in repairing an infrastructure that is crumbling, or expanding infrastructure that is now inadequate due to population shifts. According to the U.S. Department of Transportation, as of Nov. 3, 2009, nearly 8,500 highway projects have been approved under the American Recovery and Reinvestment Act, and nearly 5,000 highway projects are underway.8
Climate Change/Global Warming From power generation to automotive and nearly everything in between, this megatrend is changing the way companies – and entire industries – do business. Greener solutions that address VOC regulations continue to be an area of focus for the coatings industry. This is particularly true as new and modified regulations are on the horizon. For example, Canada has proposed a 340 g/L limit that is expected to become effective sometime in 2010,
Baseball stadium at Wide World of Sports Disney World in Florida.
and the U.S. EPA is developing an amendment to the national rule that will also be effective in 2010.9 Necessity is the mother of invention, it is said. For the protective coatings industry, the effort to minimize the use of solvents has opened the door to the development and use of more environmentally friendly alternatives, including high-solids coatings, waterborne coatings, waterborne UV coatings and powder coatings. Traditional solventborne polyurethane coatings are typically formulated at a solid level of 30-40 percent, which would
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be equivalent to a VOC level of 600 g/L or above. However, the development of lower-viscosity resins, both in the polyol component (polyesters, polyacrylates and polyaspartic esters) as well as low-viscosity polyisocyanates, enables the formulation of high-solids coatings. One approach to the market’s need for higher solids coatings is a new class of co-reactants, namely polyamino coreactants. In the past, the extremely high reactivity of primary amines has prevented their use as a viable co-reactant in coating applications. However, the significantly reduced reactivity of hindered or blocked amines, such as polyaspartic esters and aldimines has allowed for a whole new family of co-reactants available to polyurethane formulators. The coatings based on these polyamino coreactants can be formulated with solid levels in excess of 70 percent, resulting in a system with VOC levels at 2 lbs/ gal or less. The availability of various polyaspartic esters with vastly different reactivities and viscosities makes these compounds more versatile co-reactants for formulators. One can blend two or more polyaspartic esters to achieve a wide range of application viscosities and potlifes. One significant characteristic of the coatings based on polyaspartic esters is that they offer extremely high hardness, balanced with a reasonable flexibility. In addition, both aldimines and polyaspartic esters are compatible with most traditional polyester or polyacrylic resins. The polyaspartic esters can easily be blended with polyesters or polyacrylics to achieve the desired solid level/VOC, hardness, viscosity and cost. For all its advantages, the Journal of Protective Coatings & Linings singled out polyaspartics as one of the top product developments over the last 25 years.10 Successful utilization of this coatings technology was achieved at a baseball stadium at Wide World of Sports Disney World in Florida. An examination of the 125,000-square-foot stadium revealed that a membrane between the structural concrete slab and the topping slab had failed in some areas, allowing water to seep through. Left uncorrected, the leaks could cause damage to the superstructure. To stop the leaks and prevent future water seepage, a team of professionals recommended applying a new external membrane to the concrete topping. The topcoat suggested was a specially formulated color coat based on polyaspartic resins and ali-
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The World Marketplace for Protective Coatings – Opportunities and Trends
phatic isocyanates, which met stringent project requirements that called for a flexible concrete coating with lowto zero-VOCs. This was a smart solution that offered VOC compliance as well as proven long-term durability. And while traditional solventborne polyurethanes have long set the standard for high-performance coatings systems, the development of waterborne polyurethane coatings technologies are offering new, even lower-VOC solutions to the coating formulator. Two-component waterborne polyurethane coatings, when properly formulated with the wide variety of waterborne polyols available, have film characteristics similar to those of solventborne coatings. These properties include high gloss and distinctness of image (DOI), good balance of flexibility and hardness, good abrasion and chemical resistance, and good outdoor weatherability. Much progress continues to be made pertaining to waterborne chemistries. Early waterborne coatings had as much as 300 g/L of co-solvent; new commercial systems are now actually waterborne at 0-15 g/L. A key industry focus is keeping VOCs low while improving product performance. To that end, the industry continues to strive toward the formulation of waterborne coating technologies that can outperform solvent-based coatings in the highest-performing applications. The Los Angeles Unified School District #9 offers another example of the successful implementation of a more eco-friendly coating solution. An anti-graffiti coating system based on 2K waterborne technology was applied to all perimeter poured-in-place concrete walls. In addition to preserving the architect’s desired look of the concrete as a design element, this near zero-VOC coatings solution also met stringent SCAQMD and California Air Resources Board (CARB) guidelines. Often referred to as “dry painting,” powder coatings technology is another option that offers environmental and application advantages. The term “dry painting” refers to powder coatings’ lack of liquid, solvent or water, in its formula. It is applied “dry” directly to a surface in a fine powder form. Because they don’t use
solvents in their formula, powder coatings release little to zero VOCs into the atmosphere. This not only helps the environment, but it also reduces costs for finishers because they no longer have to purchase and maintain expensive pollution control equipment. In addition, most powder coating overspray that does not adhere to the substrate can be reclaimed for future use. As a result, finishers utilize nearly 100 percent of their coating material, leaving little waste and less cleanup. Despite these positive aspects, powder coating has drawbacks, as well: it is less environmentally friendly from an energy consumption perspective and, practically speaking, lacks the durability and weatherability that high-performance applications require.
Healthcare Revolution At first, it may seem unusual to include coatings used in healthcare in a discussion of industrial high-performance coatings. But there are lessons to be learned here. Today, the coatings industry is fine-tuning raw materials up to (semi-)finished materials for the healthcare industry’s product designers, resulting in system solutions. Some examples include topical tissue adhesives, which replace sutures and staples; hydrophilic coatings that facilitate catheter insertion; drug-eluting stent coatings for reduced restenosis and thrombosis, as well as anti-bacterial coatings to minimize the spread of infection. These novel applications remind those of us in the area of high-performance coatings to “think outside the box” when looking ahead to how coatings will be utilized moving forward. In other words, we must rethink the role of coatings and how they will be used differently in the future, presenting new opportunities for functional coatings – such as printed circuit boards and other applications, for example – some of which we may not yet fully understand.
Accelerated Technology Change The evolution of coatings in the healthcare industry segues nicely into the final global megatrend being
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considered for this technical discussion: accelerating technology change. One of the new technologies with implications for a number of industries is nanotechnology. With multi-walled carbon nanotubes (CNTs) it may be possible to combine the best properties of different materials – light metals and polymer compounds – resulting in a new class of materials. As an example, reinforced composite materials based on CNTs and aluminum powder may offer entirely new design opportunities in lightweight construction. CNT-containing components may have much higher mechanical strength, which may mean they can be produced with thinner walls and therefore weigh less than their counterparts of non-reinforced aluminum. The tensile strength of this new class of materials could be similar to that of steel, but weighs only half as much because of its lower density. This weight reduction may result in much improved energy efficiency and a better CO2 balance. For opportunistic protective coatings manufacturers, this may provide an opportunity to formulate new coatings technologies to protect these nano-based structures. Another growing area is coatings based on renewable raw materials, for instance, natural oil-based coatings. Natural oilbased resins, which are used where nature has provided unique structures that are technically and economically viable, may reduce the climate impact of finished products. Applications for these natural oil-based coatings include selfleveling floor coatings, secondary containment and corrosion protection. There is much potential for the protective coatings industry, as owners, architects and engineers increasingly seek out materials that may support LEED certification and its resultant tax credits. Demand for greener technologies is here to stay, and the protective coatings industry must be ready with the appropriate solutions. Functional films is yet another area with exceptionally dynamic growth potential that is pushing the boundaries of the very definition of coatings and the properties they impart to end-use components. This growth includes developments in modern film technologies, holography and polymer electronics. Nanoparticles can play an important role here, for example in electrically conductive printing inks based on nanometallic particles or carbon nanotubes or quantum dots that could be used in the future
in silicon-free organic solar cells – cells that could revolutionize power generation because they could be produced economically in large quantities. Printed light based on coating layers containing electroluminescent pigments within the film and a small source of electricity is another natural transforma-
tion of technology. Near-term applications are primarily for signage and in integral night lighting. But if one looks further into the future, one may envision that these advancements in printed light technology might someday be used to illuminate a wide range of objects in an environmentally responsible way.
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The World Marketplace for Protective Coatings – Opportunities and Trends
TIANSORB™ UV Absorbers and Light Stabilizers
Another place to look for inspiration is textiles. The technology behind flexible coatings used to provide abrasion resistance and other desirable properties for soccer balls, for example, could some day be used to formulate coatings that don’t crack or split when being exposed to harsh weather conditions for high-performance applications. Could painting ever be obsolete? Based on current developQuality First - we use medicine standard to produce ments, in the future it may be possible to eliminate the painting our coatings additives. process for bridges or other structures, and instead, wrap it in Good Service - we are committed to provide excellent film, then heat shrink it to fit, resulting in a VOC-free, defect-free service for the customers with our application knowlstructure. This represents a novel process for an organic material edge. and, furthermore, serves to illustrate how the coatings industry must “rethink” the painting process … expanding its definition to Product List (UV Absorbers embrace other innovative ways coatings may be applied. and Light Stabilizers): It sounds incredible, but it’s true. But a look at how far the TIANSORB 1130, TIANSORB 384-2, industry has come in just the last 35 years offers great optimism TIANSORB 99-2, TIANSORB 900, and excitement about the developments that will take place in TIANSORB 123, TIANSORB 292, the next 35 years. Novel chemistries will continue to evolve and TIANSORB 5100, TIANSORB 5151, address new challenges. Considering an integrated perspective TIANSORB 5060, etc. – one that considers global socio-economic factors, as well as For more information, innovative developments in industries as diverse as healthcare, We warmly welcome please contact us at: signage and even sporting goods – creates opportunities for the cross-pollination of ideas, which, in turn, provides fertile ground you to visit us at T: 0086 21 64556108/9/10 in which the next generation’s seeds of change can take root. In ACS Booth # 2909! Email:
[email protected] light of the key drivers discussed here – population growth, gloHttp: www.tianshengchem.com.cn balization/ urbanization, climate change/global warming, the healthcare revolution and accelerated technology changes – the Visit ads.pcimag.com protective coatings industry must continue its leadership role in driving innovation forward. For organizations that adopt this pci04104TianQV.indd 1 3/16/10 12:07:40 AM holistic approach, the future will be bright, indeed. 䡲
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References Dankin, M. Spanning 25 Years of Development in Heavy-Duty Coatings. J. of Protective Coatings and Linings 2009, 8, 47. 2 Kaelin, A. B.; Kapsanis, K. A. Regulations and Coatings Work: Developments Over 25 Years. J. of Protective Coatings and Linings 2009, 8, 73-74. 3 Public Infrastructure Development in China. Lin, Shuanglin Comparative Economic Studies, June 22, 2001. 4 UAEFreeZones.com. 5 U.S. Census Bureau – International Database. 6 Benjamin Tal, “Capitalizing on the Upcoming Infrastructure Stimulus,” CIBC World Markets, Jan. 26, 2009. 7 “Development of Africa’s Infrastructure Key to Economic Growth, Social Progress,” United Nations new release, Feb. 2, 2009. 8 “Highway Investment Hits $20 Billion,” U.S. Department of Transportation, Nov. 3, 2009. 9 Harding, M. Update on Low VOC Regulations for Coatings. J. of Protective Coatings and Linings 2009, 10, 23. 10 Hower, H. Top Product Developments, 1984 to the Present. J. of Protective Coatings and Linings 2009, 8, 67-68. 1
This paper was presented at PACE 2010, Phoenix, AZ. For more information, visit www.pace2010.com, www.bayermaterialscience.com and www.bayermaterialsciencenafta.com.
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The Use of
Mixed Metal Oxide Pigments
M
in Industrial Coatings
ixed metal oxide (MMO) pigments, also known as complex inorganic color pigments (CICPs), have been around since the early 1800s. Their use in the ceramic and pottery industries is well known due to their overall inertness, which contributes to outstanding heat, chemical and UV resistance. The use of MMOs in industrial coatings is less common and more for special purposes. This paper will discuss the benefits of formulating coatings with MMOs as a replacement for, or in conjunction with, the more common organic types. Mixed metal oxide pigments are compounds comprised of a group of two or more metals and oxygen. The most common crystal structures are rutile (MeO2) hematite (Me2O3) or spinel (Me3O4). Metals commonly present include: cobalt, iron, trivalent chrome, tin, antimony, titanium, manganese and
aluminum. Different metal combinations produce a wide spectrum of hues ranging from black to brown to green, blue, yellow and red. All MMOs are produced by a calcination process consisting of an intimate mixture of appropriate metal precursor materials being fired at temperatures of 800 to 1300 °C. It is this calcining process that creates the extremely stable metal oxide bonds. The chemical stability of these bonds affords the outstanding durability of this class of color pigments.
UV Durability The chemical inertness of inorganic MMOs renders their excellent resistance to UV radiation and the elements encountered in the most extreme outdoor environments. Most organic pigments degrade when exposed for more than a few years in UV-intense tropical environments. High-performance organic pigments that do provide acceptable durability
Common Mixed Metal Oxide Pigments
C.I. Name
Chemistry
CAS #
Name
Structure
Color
PBrn 33
(Zn,Fe(Fe,Cr)2O4
68186-88-9
Zinc iron chromite
Spinel
Reddish brown
PBrn 35
Fe2CrO4
68187-09-7
Iron chromite
Spinel
Dark brown
PY 53
(Ni Ti Sb)O2
8007-18-9
Nickel antimony titanate
Rutile
Yellow Yellow tan
PBr 24
(Ti, Cr, Sb)O2
68186-90-3
Chrome antimony titanium buff
Rutile
PG 17
CrOAl
68909-79-5
Chromium green
Hematite
Yellowish green
PG 26
CoCr2O4
68187-49-5
Cobalt chromite
Spinel
Green
PG 50
Co2TiO4
68186-85-6
Cobalt titanate
Rutile
Green
PG 17 Blk
CrOFe
68909-79-5
Chromium green-black
Hematite
Brownish black
PBlk 28
CuCr2O4
68186-91-4
Copper chromite black
Spinel
Black
PBlk 30
(Ni,Fe)(Cr,Fe)2O4
71631-15-7
Chrome iron nickel black
Spinel
Black
PB 28
CoAl2O4
1345-16-0
Cobalt aluminate
Spinel
Reddish blue
PB 36
Co(Al,Cr)2O4
68187-11-1
Cobalt chromium aluminate
Spinel
Turquois
PY 119
(Zn Fe)Fe2O4
68187-51-9
Zinc ferrite
Spinel
Brown
By Kevin Biller | Mason Color Pigments, East Liverpool, OH 48
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are typically very expensive, commanding two to four times the cost of a metal oxide pigment. MMOs are therefore the colorant material of choice for architectural coatings requiring extremely high durability such as the performance specified in AAMA 2605-05 (Architectural Aluminum Manufacturers Association). This specification calls for maintenance of color and gloss after 10 years exposure in south Florida.
Chemical Resistance The exceptionally stable chemical bonds characteristic of MMO pigments make them insoluble in most chemicals including strong acid and alkali, and virtually all organic solvents. Because of this insolubility, coatings formulated with MMOs will not lose color due to pigment degradation even with the most extreme exposure to aggressive chemicals. Atmospheric pollution including acid rain, volcanic fallout and waste incineration does not chemically attack these pigments. Moreover, coatings requiring resistance to strong chemical exposure such as laboratory and chemical manufacturing facilities can use MMOs and be assured of color stability.
Heat Resistance The thermal stability of MMOs is well known in the ceramic and pottery industries. This class of pigments is processed for hours at temperatures ranging from 800 to 1300 °C in their manufacture. Consequently, they are chemically and color stable at these temperatures in service. As mentioned, the ceramic industry has used mixed metal oxides for color glazes for centuries. The glazes used in ceramics are regularly fired at temperatures of 985 to 1300 °C (1800 to 2350 °F) without significant color shift. The use of MMOs in thermally stable coating formulations such as those based on silicone (polysiloxane) resins brings a palette superseding the traditional black and silver high-heat choices. This brings an attractive array of color possibilities to the designer of specialized and sport transportation such as motorcycles, ATVs and jet skis.
Infrared Reflectivity Metal oxide pigments possess unique spectroscopic properties. The infrared reflective characteristics of the cobalt chromite, cobalt titanate and chrome oxide greens make them ideal for non-detectable camouflage coatings. Common organic green pigments such as those based on copper phthalocyanine strongly absorb infrared radiation and make them a poor choice for military coatings.
region, causing a significant increase in surface temperature. This increased temperature is deleterious for a number of reasons. Most important are coatings used for architectural structures such as roofing and cladding. The heat increase associated with highly absorptive organic pigments causes the temperature of the interior of buildings to rise. This obviously translates into higher cooling costs in summer months. MMOs provide substantially higher infrared reflectivity (total solar reflectivity – TSR) and therefore stay cooler in the sunlight. The Lawrence Berkeley National Laboratory has conducted extensive research and has qualified a large amount of MMOs as replacements for poorly reflective organic pigments (http://coolcolors.lbl. gov/LBNL-Pigment-Database/database.html). IR reflective pigmentation has other practical uses. Maintaining cooler surfaces of playground equipment, park benches, outdoor sports facilities and bus stops provides more comfort and a safer surface in sunny locales. Furthermore, cooler surfaces on utility cabinetry such as cable junction boxes, electrical enclosures and outdoor generators keeps internal components cooler and increases product longevity and minimizes service calls. Mixed Metal Oxide Crystal Morphology
Crystal Type
Chemistry
Rutile
MeO2
Hematite
Me2O3
Spinel
Me3O4
Crystal Structure
Solar Reflectivity One of the more exciting developments in MMO technology is the recognition of how this pigment technology can provide colors that significantly reflect the infrared energy generated by the sun. Colored materials, including pigments and dyes, absorb and reflect radiation in the visible range (approximately 400 to 700 nm). They also inherently reflect and absorb in the near-infrared region (700 to 2500 nm) of radiation. It is this range that is responsible for the increase of temperature experienced when colored surfaces are exposed to sunlight. Organic pigments, especially carbon black and phthalocyanine types (blue and green), absorb strongly in this
Me = metal atom PA I N T & C O A T I N G S I N D U S T R Y
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The Use of Mixed Metal Oxide Pigments in Industrial Coatings
Cooler coating temperatures not only provide comfort and increased component longevity but also improve the overall durability of the coating system. The lower temperatures experienced in service keep the coating binder cooler and thus slow the chemical degradation of the polymers in the coating. Highest reflectivity is characteristic of yellows (PY 53 and PBrn 24), browns (PBrn 33 and PBrn 35), some greens (PG 17) and some blacks (PG 17 and PBrn 35). Blues (PB 28 and PB 36) and greens (PG 17, PG 26 and PG 50) provide reasonable alternatives to traditional organic types.
for an architectural or automotive coating while maintaining or improving durability. In some cases an improvement in hiding can be realized.
Organic Pigment Extenders
Summary
Mixed metal oxides can enhance the durability and lower the cost of coatings formulated with high-performance organic pigment systems. This is especially relevant in bright yellow, orange and red color spaces. These organic hues not only are relatively weak in hiding (opacifying) properties, they typically possess high oil absorption, which affect rheological properties especially at the high concentrations needed to achieve acceptable opacity. MMOs have relatively low oil absorption compared to their organic counterparts, thus providing improved flow and leveling in industrial coatings. This is especially true in powder coatings, which rely on resin melt viscosity to achieve a smooth finish. The incorporation of pigment yellow 53 or pigment brown 24 (yellow buff) typically lowers the overall cost of pigmentation
Mixed metal oxide pigment technology is well known and timetested in the decorative ceramics industry. Its widespread use in organic coatings has not yet reached its full potential. These pigments offer a multitude of benefits for the coatings formulator, including excellent outdoor durability, chemical resistance and heat stability. Inherent infrared reflective properties make them a good foundation for camouflage and “cool” coatings. The low oil absorption characteristic of MMOs allow them to reduce the concentration of high-cost, high-performance organic pigments with a positive effect on coating rheology. The coatings formulator is therefore strongly encouraged to include this class of pigments in his or her formulating toolkit. 䡲
Tinting in Pastels In general MMOs are weaker and somewhat lower in tint strength compared to organic pigments. Because of this, they are an excellent choice to tint white and pastel colors. This is especially true when compared to difficult-to-disperse organic pigments such as phthalocyanine blues and greens and carbon black.
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Novel, Environmentally Friendly Corrosion Inhibitor for
Self-Etching Wash Primers
T
his study found that an etch-primer formulation that incorporated Nubirox 301 showed comparable results in adhesion and corrosion inhibition when compared to a traditional, commercial etch primer that contained zinc tetraoxy chromate. Nubirox 301, a calcium and strontium phosphosilicate corrosion inhibitor, gives an effective and cost-efficient pathway to making an environmentally friendly self-etching primer. The formulations were applied to three different substrates (cold rolled steel, galvanized steel and aluminum) and were put through a series of tests (EIS, SEM/EDX Analysis, ASTM B 117, ASTM D 5894 and ASTM D 4585). Each of the tests concluded that, overall, the addition of Nubirox 301 showed the most advantageous results. The formulations were in compliance with low-VOC requirements; however, since the commercial etch primer contained the zinc tetraoxy chromate, it still required the reporting of that environmentally hazardous substance. Nubirox 301,
FIGURE 1 | EIS test model. Electrolyte
Reference Electrode
Coating
Corrosion Reaction
Coating Capacitance (Coating)
Uncompensated Pore Resistance Resistance (Ru) (Rpore)
Metal
Working Electrode Double Layer Capacitance (Cdl) Polarization Resistance (Rp)
however, is not only chrome-free, it is zinc-free as well – therefore, it is not required to report this inhibitor for environmental compliance.
Introduction In the automobile refinishing and industrial manufacturing industries, and where untreated or bare metal is painted, an etch primer is typically used to increase adhesion of the paint to the metal surface and to improve the anticorrosive quality of the coating. Historically, etch primers have utilized zinc tetraoxy chromate as the primary corrosion inhibitor. However due to the toxicity and carcinogenic concerns associated with chromates, as well as the dawning of the new era of “green regulations”, an environmentally friendly alternative is needed for this market. Zinc phosphate corrosion inhibitors have been studied as a replacement for zinc tetraoxy chromate in this type of application, and they have seen limited success. Historically, zinc phosphate has exhibited similar performance to chromates in real-world outside exposure. However, in harsher conditions such as marine environments and accelerated salt spray or prohesion testing, the results are less favorable; however, it is important to note that under these more harsh conditions, zinc phosphate still helps in the preservation of the metal substrate, just not to the degree the chromate presents. Even though zinc is not considered a heavy metal, it is still a requirement to report its use. Etch primers are traditionally formulated with phosphoric acid and zinc tetraoxy chromate in an alcohol medium, using polyvinyl butyral as the binder, which acts as a ligand of the reaction products. As new global environmental standards are put in place, stricter formulation guidelines will become prevalent. In the near future a push
By Rebecca R. Daley and Dr. Steve A. Hodges, Nubiola Inorganic Pigments | Nubiola USA, Norcross, GA 52
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Project Design The formulations were based on an epoxy/phenolic-modified polyvinyl butyral (PVB) system. The pigment volume concentration (PVC) of each formulation was held constant at 12%, and the PVC/CPVC ratio remained at 0.29. Four Nubirox inhibitors, and combinations thereof, were evaluated at different levels in order to determine which gave the most advantageous results. In all, there were 10 experimental data points evaluated, along with two controls (a commercially available zinc tetraoxy chromate-containing (5.5% by total formula weight) selfetching wash primer along with one that is chrome-free and utilizes zinc phosphate (5% by total formula weight)). The four Nubirox inhibitors evaluated were: • Nubirox N2 – standard zinc phosphate; • Nubirox 106 –molybdate-modified zinc phosphate; • Nubirox 213 – multiphase iron and zinc phosphate; and • Nubirox 301 – calcium and strontium phosphosilicate; along with a 1:1 ratio of combinations of the following inhibitors: • Nubirox 213 : Nubirox 106; • Nubirox 213 : Nubirox 301; and • Nubirox 106 : Nubirox 301. The inhibitors were evaluated at two loading levels, 1.5% total formula weight (t.f.w.) and 3.0% t.f.w. – with the exception of the Nubirox N2, which was only evaluated at 1.5% t.f.w. Each combination of inhibitors was evaluated at the loading of 1.5% t.f.w. per inhibitor. The formulations were evaluated over three types of substrates – galvanized steel, cold rolled steel and aluminum. A total of 432 panels were coated via spray application using a HVLP (high-volume low-pressure) spray gun. The top half of each panel showed the self-etching primer alone, and the lower half showed the etch primer along with a commercially available intermediate sanding primer. One panel for each test was also sprayed with a commercially available acrylic topcoat. Characterization of the film formed by the etch-primer formulations was done via Electro-Impedance Spectroscopy (EIS, see Figure 1) and SEM/EDX analysis. The panels were allowed to rest for 7 days before corrosion testing began. They were then evaluated to assess blistering, rusting and adhesion via accelerated ASTM D 4585 humidity testing, ASTM B-117 salt spray testing, as well as ASTM D 5894 cyclic QUV/prohesion testing.
FIGURE 2 | EIS values from the highest performance formulations. 109 100
acdcac: -2 V, 20 min, 25 min EIS, 3h relax
107
60
105
40 103 101 10-4
Phase Θ (*)
80
20 10-2
100 102 Frequency (Hz)
104
0 106
FIGURE 3 | SEM/EDX mapping. Exp. 7
Exp. 6
Exp. 5
Exp. 4
Exp. 3
Exp.
Exp. 2
Control
TABLE 1 | Aluminum salt spray evaluation. Aluminum Visual Rating TEST TYPE: ASTM B 117 Hrs in Test: 309 % Addition (t.f.w.)
Inhibitor
Blister
Scribe Rust
Field Rust
5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
D4 None MD2 M2 None
10 10 10 10 10
10 10 10 10 10
TABLE 2 | Aluminum Prohesion evaluation. Aluminum Visual Rating TEST TYPE: ASTM D 5894 % Addition Inhibitor (t.f.w.) 5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
Hrs in Test: 537 Blister
Scribe Rust
Field Rust
MD4 None MD4 D2 None
10 10 10 10 10
10 10 10 10 10
PA I N T & C O A T I N G S I N D U S T R Y
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Exp. 1 Exp. 2 Control Exp. 3 Exp. 4
Biode Diagram
|Z| Ω
to lower VOCs and HAPS-free systems, to eliminate chrome, to limit reportable compounds, and to develop water-based hybrids are in store for the etch-primer market. The objective of the work presented herein was to develop a chrome-free self-etching primer that meets current and future global environmental demands, as well as offer improved performance over an existing chrome-free formula utilizing zinc phosphate and comparable to improved results to an industry-standard zinc tetraoxy chromate-containing etch primer. A range of Nubirox corrosion inhibitors were evaluated in this study in order to determine which chrome-free inhibitor showed the best results.
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Novel, Environmentally Friendly Corrosion Inhibitor for Self-Etching Wash Primers
FIGURE 4 | Salt spray pictorial results.
FIGURE 5 | Cyclic QUV/prohesion pictorial results.
2K PVB Etch / Wash Primer C.R.S. / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 309 hours Salt Spray Testing (ASTM B117)
FIGURE 6 | Additional testing using a different 2K self-etching wash primer.
2K PVB Etch / Wash Primer C.R.S. / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 537 hours QUV/Probation Testing (ASTM D5834)
2K PVB Etch / Wash Primer C.R.S. / D.F.T ~ 0.8 Mils 301hours Salt Spray Testing (ASTM B117)
Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 213 Nubirox 106 Nubirox 301 Tetraoxy Chromate Percentages based on total formula weight
Figure 4 (a): Cold Rolled Steel
Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 301 Nubirox 106 Nubirox 213 Tetraoxy Chromate Percentages based on total formula weight
Figure 5 (a): Cold Rolled Steel 5.5% Lf.w Zinc Tetraoxy Chromate
2K PVB Etch / Wash Primer
2K PVB Etch / Wash Primer
Aluminum / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 309 hours Salt Spray Testing (ASTM B117)
Aluminum / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 537 hours QUV/Probation Testing (ASTM D5834
1.5% Lf.w Nubriox 301
3.0% Lf.w Nubriox 301
3.0% Lf.w Nubriox 213
Figure 6 (a): ASTM B 117 (Cold Rolled Steel) 2K PVB Etch / Wash Primer C.R.S. / D.F.T ~ 0.8 Mils /504 hours Cyclic QUV/Probation Testing(ASTM D5894)
Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 301 Nubirox 106 Nubirox 213 Tetraoxy Chromate Percentages based on total formula weight
Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 213 Nubirox 106 Nubirox 301 Tetraoxy Chromate Percentages based on total formula weight
Figure 5 (b): Aluminum
Figure 4 (b): Aluminum
2K PVB Etch / Wash Primer 2K PVB Etch / Wash Primer
Galvanized Steel / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 537 hours QUV/Probation Testing (ASTM D5834)
Galvanized Steel / D.F.T ~ 0.7 Mils (top) ~3 Mils (bottom) / 309 hours Salt Spray Testing (ASTM B117
5.5% Lf.w Zinc Tetraoxy Chromate
1.5% Lf.w Nubriox 301
3.0% Lf.w Nubriox 301
3.0% Lf.w Nubriox 213
Figure 6 (b): ASTM D 5894 (Cold Rolled Steel) 2K PVB Etch / Wash Primer Galvanized Steel / D.F.T ~ 0.8 Mils /301 hours Salt Spray Testing (ASTM B117)
Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 301 Nubirox 106 Nubirox 213 Tetraoxy Chromate Percentages based on total formula weight
Figure 4 (c): Galvanized Steel Each test contained three replicates of each experimental and of each control – one topcoat along with two etch/etchintermediate panels. The ASTM D 4585 humidity testing was conducted for a set 94 hours; however, in the other tests the panels were periodically evaluated and when enough differential was seen among all the experiments as well as the controls, the panels were removed from test, the middle portion of the film was stripped, and the metal beneath the film was then evaluated via ASTM D 610 for panel corrosion, ASTM D 1654 for scribe corrosion and ASTM D 714 for panel/scribe blister.
Results The EIS values from the highest performance formulations can be seen in Figure 54
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Control 1 5.0% Zinc Phosphate
Control 2 3.0% 1.5% 3.0% 5.5% Zinc Nubirox 301 Nubirox 106 Nubirox 213 Tetraoxy Chromate Percentages based on total formula weight
Figure 5 (c): Galvanized Steel 2. As can be seen, Nubirox 301 at 3% by t.f.w. (shown as Exp 2 denoted by red circles) exhibited similar trend in impedance values as that of zinc tetraoxy chromate (shown as control denoted by green triangles). The remaining experiments denoted on the chart are as follows: Exp. 1 Nubirox 106 at 1.5% by t.f.w., Exp. 3 Nubirox 213 at 3% by t.f.w., and Exp. 4 Nubirox N2 at 1.5% by t.f.w. SEM-EDX is the name of the energydispersive X-ray spectroscopy analysis conducted by means of scanning electron microscopy. It is an analytical technique used to determine the chemical composition of a given specimen as well as its morphology and structure. SEM-EDX analysis was employed in this study for mapping quantitative and qualitative oxidation generation on the surface of the various substrates.
5.5% Lf.w Zinc Tetraoxy Chromate
3.0% Lf.w Nubriox 213
1.5% Lf.w Nubriox 106
1.5% Lf.w Nubriox 301
3.0% Lf.w Nubriox 301
Figure 6 (c): ASTM B 117 (Galvanized Steel) 2K PVB Etch / Wash Primer Galvanized Steel / D.F.T ~ 0.8 Mils /504 Cyclic QUV/Probation Testing(ASTM D5894)
5.5% Lf.w Zinc Tetraoxy Chromate
3.0% Lf.w Nubriox 213
1.5% Lf.w Nubriox 106
1.5% Lf.w Nubriox 301
3.0% Lf.w Nubriox 301
Figure 6 (d): ASTM D 5894 (Galvanized Steel)
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Novel, Environmentally Friendly Corrosion Inhibitor for Self-Etching Wash Primers
TABLE 3 | Cold rolled steel salt spray evaluation. Cold Rolled Steel Visual Rating TEST TYPE: ASTM B 117 Hrs in Test: 309 % Addition Inhibitor Blister Scribe Rust (t.f.w.) 5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
None None D2 M4 M2
Field Rust
7 5 8 8 6
3 2 3 6 4
TABLE 4 | Cold rolled steel Prohesion evaluation. Cold Rolled Steel Visual Rating TEST TYPE: ASTM D 5894 Hrs in Test: 537 % Addition (t.f.w.)
Inhibitor
Blister
Scribe Rust
Field Rust
5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
None F2 MD4 F4 None
7 9 7 7 10
2 10 3 6 10
TABLE 5 | Galvanized steel salt spray evaluation. Galvanized Steel Visual Rating TEST TYPE: ASTM B 117 Hrs in Test: 309 % Addition (t.f.w.)
Inhibitor
Blister
Scribe Rust
Field Rust
5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
F2 None None None None
10 10 10 10 10
8 9 8 7 10
TABLE 6 | Galvanized steel Prohesion evaluation. Galvanized Steel Visual Rating TEST TYPE: ASTM D 5894 Hrs in Test: 537 % Addition Inhibitor Blister Scribe Rust Field Rust (t.f.w.) 5% 5.5% 3% 1.5% 3%
Zinc phosphate Zinc tetraoxy chromate Nubirox 213 Nubirox 106 Nubirox 301
MD4 None F4 D3 None
9 10 10 9 10
8 10 7 7 10
FIGURE 7 | Paint film depiction of phosphoric acid reaction to form the passive layer. Paint Film Ca+2
Sr+2
Sr+2
Ca+2
Ca+2
Sr+2 H3PO4 -
H3PO4 -
Passive Layer (CaO · SrO · P2O5 ) Substrate
[Ca2SiO4·3SrCO3 + 2H3PO4 + XH2O → 2CaO·Sr3(PO4)2·SiO2 + XH2O + 3CO2↑] 56
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The pictorial results from the SEM/EDX analysis are shown below in Figure 3. As with the EIS values, the results from this analysis show that the Nubirox 301 at 3% by t.f.w. is most comparable to the 5.5% by t.f.w. zinc tetraoxy chromate. Exp. 1-4 shown are the same from the EIS evaluation; Exp 5-7 are the 1:1 blends. In accelerated corrosion testing, overall the best results were seen with the addition of Nubirox 301 at 3.0% t.f.w. Nubirox 301, in both salt spray and prohesion tests and on all substrates, showed better adhesion promotion, less field corrosion, and comparable to improved scribe rust inhibition in comparison to the control utilizing 5% by t.f.w. standard zinc phosphate. Nubirox 301 at 3.0% t.f.w. also had comparable to improved results to the etch primer containing 5.5% by t.f.w. zinc tetraoxy chromate (Figures 4 and 5). The salt spray (ASTM B 117) testing was pulled after 309 hours, and the cyclic QUV/prohesion (ASTM D 5894) testing was pulled after 537 hours. Additional testing was conducted using a slightly different 2K self-etching wash primer. These results (Figure 6) also show Nubirox 301 having advantageous results when compared to zinc tetraoxy chromate in both the ASTM B 117 and the ASTM D 5894 testing on cold rolled and galvanized steel. These additional pictorial results show the etch primer alone – with no intermediate primer. As stated previously, each panel was rated via ASTM D 610 for panel corrosion, ASTM D 1654 for scribe corrosion, and ASTM D 714 for panel/scribe blister. Tables 1 through 6 give the detailed ratings of the experiments that exhibited the best results (correlating pictorial results from Figures 4 and 5). The blister ratings are as follows: F (for few), M (for medium), MD (for medium dense) and D (for dense) – along with a number to designate the percent of area affected. The field rust rating ranges from 10 (being no area affected) to 0 (being over 50 percent rusted). The scribe rust rating ranges from 10 (being no rust from scribe) to 0 (being over 16 mm rust from scribe). Each of these rating scales is directly taken from the respective ASTM.
Summary It is apparent by both the pictorial results and the ASTM evaluations that Nubirox 301 presents a favorable alternative to chrome in a 2K epoxy/phenolic PVB etch primer system. The results show that Nubirox 301 shows overall comparable results to zinc chromate in this system, and in most cases out-performs standard zinc phosphate, which is the current alternative. Nubirox 301, an “eco-friendly” zinc-free corrosion inhibitor, meets both the ever increasing and limiting environmental demands, as well as the performance requirements needed for this type of application. Nubirox 301 is a calcium and strontium phosphate complex carried on a silicate core. The calcium and strontium cations provide direct anodic inhibition, where the silica-core alkalinity provides good cathodic inhibition. This chemical composition works within the etch-primer formulation and reacts with the phosphoric acid to form the passive layer seen in Figure 7. In addition to the chemical activity of this corrosion inhibitor, Nubirox 301 has a unique particle morphol-
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Novel, Environmentally Friendly Corrosion Inhibitor for Self-Etching Wash Primers
ogy, a fine mean particle size, along with a narrow particle size distribution (Figure 8) – thus providing more uniform pigment packing, which allows for excellent thin-film performance. This is ideal for the etch primer market, seeing that the primer is typically applied at less than 1 mil (25 µ) dry film thickness. It also lends to the excellent package stability found with Nubirox 301 in this system.
FIGURE 8 | SEM and Malvern sedigraph of Nubirox 301. 500μ
Conclusions
Nubirox 301 Particle Size Distribution (Malvern Sedigraph) 50%
0.01
0.1
100% 90 80 70 60 50 40 30 20 10 0
1.0 10.0 100.0 Particle Diameter (μm.) Avg. Particle Size = 1.0 μ
1000.0
• Nubirox 301 at an addition of 3.0% t.f.w. in a 2K epoxy/phenolic-modified PVB self-etching wash primer showed comparable results vs. a commercially available zinc tetraoxy chromatecontaining etch primer. • Nubirox 301 (zinc-free) was the most effective non-chrome inhibitor for multi-substrates. • Nubirox 301 is a calcium and strontium phosphate complex carried on a silicate core; therefore, it is not only chrome-free, it is zinc-free as well. Thus it is the most eco-friendly alternative available. There are no components of this inhibitor that are required to be reported. • The fine particle size of Nubirox 301 is ideal for thin film systems such as etch primers. 䡲
Acknowledgements
• Nathan Karszes, Laboratory Manager, Nubiola North American Technology Center. • Richard March Raurell, R&D Manager, Nubiola Spain.
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Paint Formulations and the Need for Zeta Potential As latex waterborne paints command a growing share of the market, zeta potential measurement and its manipulation is increasingly important for product optimization.
P
aints are multi-component systems formulated to produce specific product properties. The rate and uniformity at which these coatings wet spread and coalesce into a film can be controlled by the constituents in the formulation. Depending on their end use, coatings can have four or more components in their mixture. Solid or higher-viscosity components consist of pigments used to obtain a specific color, and oil emulsions or latex components that provide film formation or coating properties. Both are mixed with a number of water-soluble materials, such as surfactants, silanes, viscosity modifiers, processing aids, color aids and polyelectrolytes, which can also be surface active. These water-soluble surface-active elements can affect the surface chemistry or interfacial behavior of the solid particle components. The soluble components play a vital role in the final film properties and color of a paint formulation, and can be studied using zeta potential. Zeta potential is a physical property exhibited by any particle in suspension. It can be quantified using elec-
Zetasizer Nano
trophoretic mobility (electrophoresis) measurement and adjusted to optimize coating formulations. Studying zeta potential results enables the building of relationships between the chemical composition of formulated coatings and the required final physical properties and color. Today, zeta potential is easy to measure and aids in predicting long-term stability and optimizing product properties.
Electrophoresis When an electric field is applied across an electrolyte, suspended charged particles are attracted to the electrode of opposite charge. Viscous forces acting on the particles tend to oppose this movement. When equilibrium is reached between the two opposing forces, the particles move with constant velocity. This velocity depends on electric field or voltage gradient strength, the dielectric constant of the medium, its viscosity and the zeta potential. A particle’s velocity in a unit electric field is known as its electrophoretic mobility. Zeta potential is related to electrophoretic mobility through the Henry equation, which relates it to zeta potential based on physical constants such
By Ana Morfesis | Malvern Instruments Inc., Westborough, MA 60
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as the dielectric constant, viscosity and ionic strength of the medium. Current instrumentation makes zeta potential measurement easy and automatic.
Measuring Electrophoretic Mobility The essence of a classical micro-electrophoresis system is a capillary cell with electrodes at either end, to which a potential is applied. Particles move towards the electrode, their velocity is measured and is expressed in unit field strength as their mobility. Early methods involved direct observation of individual particles using ultra-microscope techniques. This procedure suffers from a number of disadvantages, including the strenuous effort required to make a measurement, particularly with small or poorly scattering particles. Modern methods, however, are fully automated. One of the most widely used systems is the Zetasizer Nano (Malvern Instruments), which combines laser Doppler electrophoresis with phase analysis light scattering (PALS) in the patented M3-PALS technique. This allows measurement of particle electrophoretic mobility even in samples with low mobility and also in high-conductivity samples. In addition, the low voltages involved avoid any risk of sample effects due to heating.
• Electrostatic or charge stabilization is the effect on particle interaction due to the distribution of charged species in the system. Each mechanism has its benefits for particular systems. Steric stabilization is simple, requiring only a suitable polymer. However, it can be difficult subsequently to flocculate the system if this is what is required. Expense may be a drawback, and sometimes it is not desirable to have a polymer present. Electrostatic or charge stabilization works by simply altering the concentration of ions in the system – a reversible and potentially inexpensive process. Zeta potential has long been recognized as a very good index of the magnitude of the interaction between colloi-
FIGURE 1 | Optical configuration of the Zetasizer Nano series for zeta potential measurements. 6
7
Combining optics
Compensation Scattering optics beam
Beam splitter Incident beam
Attenuator Cell
Optical Configuration Laser
tec
tor
1 De
A zeta potential measurement system consists of six main components (Figure 1). First, a laser [1] is used as a light source to illuminate the particles within the sample. For zeta potential measurements, this is split to provide an incident and reference beam. The incident beam passes through the center of the sample cell [2], and the light scattered at a forward angle is detected [3]. When an electric field is applied across the cell, any particles moving through the measurement volume will cause the intensity of light detected to fluctuate with a frequency proportional to the particle speed, and this information is passed to a digital signal processor [4] and onto a computer [5]. The Zetasizer Nano software, for example, produces a frequency spectrum from which the electrophoretic mobility and hence zeta potential information is calculated. The intensity of the detected, scattered light must be within a specific range for the detector to successfully measure it. This is achieved using an attenuator [6], which reduces the intensity of the laser and, hence, reduces the intensity of the scattering. To correct for any differences in the cell wall thickness and dispersant refraction, compensation optics [7] are installed to maintain optimum alignment.
2
Reference beam
Digital signal processor
5
4
3
FIGURE 2 | Steric and electrostatic stabilization mechanisms of colloidal dispersions.
Stability and Interfacial Surface Effects Two fundamental mechanisms affect dispersion stability (Figure 2). • Steric repulsion – where polymers added to the system adsorb onto the particle surface and preventing particle surfaces coming into close contact. When sufficient polymer adsorbs, the thickness of the coating is enough to maintain particle separation through steric repulsion between the polymer layers. At such separations the van der Waals forces are too weak to cause the particles to adhere.
Steric stabilization
Electrostatic stabilization
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Paint Formulations and the Need for Zeta Potential
FIGURE 3 | Schematic representation of zeta potential. Electrical double layer Stern layer
Diffuse layer
from the surface, the surface would be uncharged. In fact silver ions dissolve preferentially, leaving a negatively charged surface. If Ag+ ions are now added the charge falls to zero. Further addition leads to a positively charged surface.
Adsorption of Charged Species (Ions and Ionic Surfactants) Surfactant ions may be specifically adsorbed on the surface of a particle, leading, in the case of cationic surfactants, to a positively charged surface and, in the case of anionic surfactants, to a negatively charged surface.
The Electrical Double Layer Negatively charged particle
Slipping plane
Based on the above mechanisms, latexes, pigments and in fact most materials suspended in aqueous media, carry a surface charge. The development of a net charge at the particle surface affects the distribution of ions in the surrounding interfacial region, resulting in an increased concentration of counter ions (ions of opposite charge to that of the particle) close to the surface. Thus an electrical double layer exists round each particle.
Zeta Potential
Surface potential Zeta potential
mV
Distance from particle surface dal particles. Zeta potential measurements are commonly used to assess the stability of colloidal systems.
Origins of Surface Charge Most colloidal dispersions in aqueous media carry an electric charge. This can originate in many ways depending upon the nature of the particle and its surrounding medium. The more important mechanisms are the ones considered here.
Ionization of Surface Groups Dissociation of acidic groups on the surface of a particle will give rise to a negatively charged surface. Conversely, a basic surface will take on a positive charge. In both cases, the magnitude of the surface charge depends on the acidic or basic strengths of the surface groups and on the pH of the solution. The surface charge can be reduced to zero by suppressing surface ionization – by decreasing the pH for negatively charged particles or increasing it for positively charged particles.
Differential Loss of Ions from the Crystal Lattice As an example, consider a crystal of silver iodide placed in water. If equal amounts of Ag+ and I- ions were to dissolve 62
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The liquid layer surrounding the particle exists as two parts; an inner region (Stern layer) where the ions are strongly bound and an outer (diffuse) region where they are less firmly associated. Within the diffuse layer there is a notional boundary inside which the ions and particles form a stable entity. When a particle moves (e.g., due to gravity), ions within the boundary move with it. Those ions beyond the boundary stay with the bulk dispersant. The potential at this boundary (surface of hydrodynamic shear) is the zeta potential (Figure 3). The magnitude of the zeta potential gives an indication of the potential stability of the colloidal system. If all the particles in suspension have a large negative or positive zeta potential then they will tend to repel each other and there is no tendency for the particles to come together. However, if the particles have low zeta potential values then there is no force to prevent the particles coming together and therefore they will flocculate or coagulate.
What This Means for Coatings Historically, coatings have been formulated as solventborne (oil-based paints) or waterborne paints (latex, water-based paints). Environmental requirements limiting VOCs have mandated the reduction of solvent concentration in coating products. Other factors such as ease of use have helped minimize consumer use of oil-based paints. Therefore latex, waterborne paints command an ever-increasing share of the market. It is easy to study zeta potential in these coatings and, because of the additives and formulated nature of the products, manipulating zeta potential is highly relevant as an optimization tool. Specifically, because water has a high surface tension, waterborne paints present unique formulation challenges. It is more difficult to wet the non-polar components of the formulation, such as pigments, etc. Also, because of the physical properties of the oil and polymers used in these aqueous based dispersions, the film formation characteristics of the latex paints themselves tend to be restricted.
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Paint Formulations and the Need for Zeta Potential Type ZY Premium Type ZY Type ZS
FIGURE 4 | Zeta potential versus adsorption of a processing aid.
Type Z
®
SiLibeads
King„ of all Beads” strong powerfull
Zeta Potential, [mV]
Type GZ
50 40 30 20 10 0 -10 0 -20 -30
ZP
5
10
15
20
Additive Concentration, [ml] FIGURE 5 | Paint formulation versus zeta potential and surface defects. ZP
Zeta Potential, [mV]
Surface Defects
than just grinding media
300
20
200
10
100
0
0 1
2
3
-10
4 -100
-20
-200
Paint Formulation
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Therefore, a variety of additives including surfactants (wetting agents), processing aids and polyelectrolytes, play an important role in latex (waterborne) paint products. As the particle concentration increases during wetting, spreading and coalescence of the coating, the viscosity increases. Based on this scenario, there is a point of phase inversion where the latex particles touch and deform into what will become the continuous phase – the film/coating. The process of film formation goes through four steps: (1) discrete emulsion particles; (2) concentration of the particles or evaporation of the water phase; (3) coalescence where the particles deform; and (4) maturation or diffusion of the chains. Waterborne paints require additives to build the interfacial characteristics to achieve the desired stability for the storage and film formation characteristics needed in the final product. Amongst other properties these include good wetting, uniform film formation, zero defects, specific color, brightness, long-term adhesion and strength. Zeta potential provides a measurement technique that allows the study of latex and pigment components, and also of additives and their possible combinations. Such data provides insight into the particle interfacial structure and allows optimization of each component in the formulation to give the desired final product properties. Figure 4 shows a latex or film former study as a function of a surface-active processing aid. These data represent an initial step
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in understanding how various additives interact with the surface of a film former in a paint formulation. The results indicate that this specific processing aid does adsorb to the surface of the latex, which has a -20 mV zeta potential initially without any additive. It reverses charge and becomes cationic with increased addition of a cationic processing aid. This type of data not only shows surface activity but also indicates the optimal concentration required for the processing aid to be effective. Figure 5 shows a study of a series of paint formulations prepared with the identical latex and pigment components but having different additives. Labeling these formulations as Paint 1 through 4 in the order of the highest negative zeta potential to highest positive zeta potential, and relating zeta potential to coating defects of the final product, a clear trend arises. In this case it indicated that a cationic formulation resulted in fewer defects per 100,000 parts.
dispersed particulates and can be related to the required final product properties. 䡲
References 1. Henry, D.C. Proc.Roy. Soc, 1931, A133, 106. 2. Hunter, R.J. Introduction to Modern Colloid Science, Oxford University Press, 1993. 3. Chevalier, Y., Pichot, C. Graillar, C., Joancot, M., Wong, K., Maquet, J., Lindner, P., and Cabane, B. Colloid & Polymer Sci. 1992, 270, 806. 4. Winnik, M.A. and Wang, Y., J. of Coatings Tech.1992,64 (811), 51. 5. Davidson, G. and Lane, B. Eds. Additives in Waterborne Coatings, RSC, 2003. 6. Conley, R. F. Practical Dispersion: A Guide to Understanding and Formulating Slurries, VCH Pub. Inc., 1996.
For more information, visit www.malvern.com or call 508/768.6400.
Conclusion In conclusion, paints are multi-component systems formulated to produce specific product properties. The rate and uniformity at which these coatings wet spread and coalesce into a film can be controlled by the chemical components used in the formulation. Coatings, depending on their end use, are complex formulations with a minimum of four components added into a dispersed mixture. Zeta potential measurements provide insight into the stability of the latex and pigments in the dispersion. Zeta potential also helps to elucidate the interfacial characteristics of the
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Alkyd Latexes: Opening the Door for a Greener Tomorrow
A
s environmental regulations and the “go green” era continue to be the driving force of current coatings resin development, the importance of having a versatile, low-VOC resin is evident. With the chemical industry affected by the economic crisis that is being experienced globally, many companies have downsized their staff, production and research capabilities. This makes it hard for paint companies to delve into new research areas, as they are constantly reformulating product lines to meet current and future acceptable VOC levels as they also strive for “green” certification. The green certification process, available from a variety of independent third parties, is offered to companies and regarded as a positive from many consumers’ perspectives and has become a crucial part of new product development for several industries. These certification programs have a list of certain criteria that are required for a product to boast their stamp of approval. In addition, existing and novel coatings products must continue to meet allowable levels of VOCs in both architectural and industrial paints that vary from region to region. As the uncertainty of the economic situation continues, wouldn’t it be nice to have a multipurpose resin that can be used in multiple applications that easily meets current and future VOC allowances and qualifies for green certification?
Green Certification Programs While the environmental component emerges as an important aspect in a consumer’s decision, certification
programs have been developed to help ensure the environmental benefits of specific products. These certifications are offered by independent third parties and typically entail a detailed certification process. Most programs for the coatings industry are focused on chemical exemptions, VOC limits, performance requirements and packaging constraints. Currently, reputable programs for a broad range of products, including coatings products, are Green Seal, Ecologo and the Coatings Research Group, Inc.’s Green Wise. Other programs exist, but are targeted toward specific market segments. Table 1 provides a summary of the certification plans and criteria for different coatings applications. All of the certification programs outlined in Table 1 are currently the most frequently used across the coatings industry. It is evident the renewable resource content of the product does not play a role in any of these certification processes. As more of these organizations are developed and the definition of what characterizes a green product continues to evolve, one can presuppose that in the future the renewable resource content of a product will be pertinent for green certification.
History of Alkyds Alkyd chemistry has been a strong force in the coatings industry for many years. The chemistry, although very established, still has room for growth as the focus on materials from renewable resources continues to develop. Although alkyds have predominantly been available in organic vehicles, the thrust to develop supe-
By Jamie Dziczkowski, Ph.D., Chemist Associate, Coatings Technology | Reichhold, Inc., Research Triangle Park, NC 66
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Alkyd Latexes: Opening the Door for a Greener Tomorrow
rior waterborne alkyds has been set in motion. Waterborne alkyd technologies including water reducible alkyds, alkyd dispersions, and alkyd latexes have been commercially available for several decades. Although still possessing some of the positive attributes of alkyd resins, these first-generation waterborne alkyds were inferior to the acrylic latex due to their poor hydrolytic stability. Today, several large resin suppliers have brought a number of alkyd dispersions and alkyd latexes to the table that mimic solventborne alkyd performance while providing desired hydrolytic stability. One attractive component of alkyd chemistry is the ability for oxidation that is contributed from the oil component of the polymer. Oxidation occurs through the unsaturated moieties that are found along the pendant fatty acid chains. The benefits presented by an oxidizable system are evident. With an alkyd-bound coating, the
initial film exhibits good flow and leveling characteristics due to the low molecular weight, low glass transition temperature (Tg) and flexibility of the polymer chains. Then, following air crosslinking, the final film exhibits good adhesion, hardness, gloss and corrosion resistance. The film formation for an alkyd resin is depicted in Figure 1. By starting with a low-molecular-weight polymer, the lack of coalescent helps keep the VOC to a minimum when moving to an aqueous carrier.
Using Alkyd Latexes to Achieve Green Products New-generation alkyd latexes, including the Beckosol® AQ line of alkyd latexes currently available from Reichhold, are made by the introduction of external surfactants and advanced processing techniques that offer a stable latex in a continuous aqueous phase. These stable latexes are achieved by careful selection of the surfactant system
TABLE 1 | Certification plans and criteria summary for coatings applications. Company Green Seal
Ecologo
Green Wise (CRGI 1)
Green Guard Institute
Standard #/Key Requirements2
Product Type
Floor Care Prducts
GS-40 Specific performance requirements, nontoxic, non-corrosive, nonsensitizing, FP > 150 °C, recyclable packaging, no APE's or heavy metals
CCD-147 Specific performance requirements, VOC limits, no halogenated solvents, no isocyanate or polymers of urethane, free monomer content < 50 ppm, pH < 12.5, be biodegradable as described
na
na
Paints/ Coatings
GS-11 Specific performance requirements, compound prohibitions (APEs, phthalates, heavy metals), VOC limits, conusmer education, packaging/ labeling
CCD-047 Specific performance requirements, no aromatic or halogenated compounds, no formaldehyde, MEK, or AN, FP > 142 °C, VOC limits
CRGI Green Wise Specific performance requirements depending on type of paint, VOC limits, chemical component limitations (no aromatics, phthalates, MEK, heavy metals)
GGPS.EC.016 Allowable limits of styrene, formaldehyde, and aldehydes, VOC levels must meet (SCAQMD) Rule #1113, top coats must meet Green Seal Standard GS-11, anti- corrosive paints must meet chemical requirements of Green Seal Standard GS-03
RecycledContent Latex Paints
GS-43 Specific performance requirements, compound prohibitions (aromatics, phthalates, metals, ketones), VOC limits
CCD-048 Specific performance requirements, > 50% post consumer material by volume, na chemical prohibitions ( APEs, aromatics, MEK, metals), FP > 142 °C, VOC limits
Stains and Finishes
GS-47 Specific performance requirements, compound prohibitions (APEs, phthalates, metals, halogenated solvents), VOC limits, VAC limits, packaging requirements
See Paints and Coatings Specifications (CCD-047)
CRGI Green Wise Specific performance requirements depending on type of paint, VOC limits, chemical component limitations (no aromatics, phthalates, MEK, heavy metals)
na
GGPS.EC.016 Allowable limits of styrene, formaldehyde, and aldehydes, VOC levels must meet (SCAQMD) Rule #1113, top coats must meet Green Seal Standard GS-11, anti- corrosive paints must meet chemical requirements of Green Seal Standard GS-03
1
Coatings Research Group, Inc. Summary of requirements. For detailed qualifications please visit the corresponding website. http://www.greenseal.org/ http://www.terrachoice-certified.com/en/ http://www.greenwisepaint.com/performance-standards.aspx http://www.greenguard.org/
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Alkyd Latexes: Opening the Door for a Greener Tomorrow
FIGURE 1 | Benefits of oxidation in an alkyd system.
Alkyd - low MW & flexible polymer chain
O2 + driers
Crosslinking
Excellent wetting due to low MW and low Tg Air-crosslinking to build molecular weight and coating performance and precise control of the emulsion process. A key factor for stabilization is attaining small emulsion particle diameters. The quality of the latex is dependent on the surface tension present in the particles. Alkyd latexes can be prepared by either direct emulsification or a phase inversion process. By achieving stable emulsions through the introduction of a protective surfactant shell, the core
alkyd resin is stabilized and hydrolysis rates are hindered. This type of system addresses the VOC issue and provides the benefits of a traditional alkyd resin. See Figure 2 for a pictorial description of an alkyd binder in a latex paint stabilized by an outer protective layer. One benefit of alkyd latex-based paint is once the coating is applied, the low-molecular-weight, low-Tg alkyd resin crosslinks through the traditional oxidative crosslinking mechanism characteristic of alkyd resins. This eliminates the need for expensive coalescing solvents and additives that are needed in acrylic latex paints in order to get excellent application properties. Another benefit of alkyd latexes is that it formulates like a typical latex paint. Standard latex rheological additives, dispersants and defoamers are effective in developing alkyd latex paints. Thus, once a system is established with an alkyd latex, formulating chemists will have more time to spend on new R&D instead of reformulating. This is all a result of the <50 g/L VOC capabilities of the alkyd latexes. Furthermore, new waterborne alkyd technology is applicable to all classes of alkyds including long, medium and short oils as well as modified systems. This allows for a wide range of architectural and industrial product development based on a single technology. An added benefit of alkyd latexes is the renewable resource content that is contributed by the use of different plant/vegetable oils
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and industrial paints. With the near-zero VOC capabilities of these products, the ability to meet current and future allowable VOC levels are made easy and convenient through one product line. In addition, the renewable resource content that is contributed by the use of different plant/ vegetable oils during polymer synthesis
FIGURE 2 | Core alkyd resin stabilized by an external surfactant protective shell.
Surfactant Shell Surfactant Shell
nts me Pig
Core
Water
Core Alkyd Alkyd Resin
is an extra benefit as the focus on green technology continues to advance. The versatility of said resins contributes to a more efficient production and inventory system as companies continue to face the effects of a challenging global economy.䡲 For more information, visit www.reichhold.com.
Resin
Water:
Polymeric Binder
Water: ContinuousPhase Phase Continuous
Rh eo Ad logi dit cal ive s
during polymer synthesis. As a specific example, the Beckosol AQ line contains up to 50% renewable material on a solids basis. Though renewable resource content is not a current requirement to obtain the green label from several agencies, as the development of what constitutes a green product continues to advance, renewable resource content could and probably will play a pertinent role as the third-party agencies seek to differentiate themselves from one another. Hence, converting to a product line based on alkyd latex provides a number of benefits and a head start in future markets.
Using Alkyd Latexes to Attain Green Assets Since more companies are commercializing products based on the new and improved waterborne alkyds, realization of the convenience of such a technology is beginning to broaden. These product lines include but are not limited to deck stains, primers, gloss enamels and industrial paints. As research on the new generation of alkyd latexes continues it is anticipated that more companies will convert existing product lines to alkyd latex-based products. Furthermore, with the uncertainty of the current global economic crisis, companies are searching for ways to cut cost on manufacturing, raw materials and inventory. The use of the new generation of alkyd latexes will aide to achieve these goals as companies attempt to rebuild their staff and research capabilities. Finally, with the near-zero VOC capabilities of the technology, the need for having different formulas for different regions will also dissipate.
Summary Alkyd latexes are versatile polymers that can be used to develop both architectural
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Achieving Ideal Dispersions in Coatings The Case for Basket Mills
W
hen providing samples for mill equipment testing, coatings manufacturers often submit large batches of the most challenging products to grind. Their logic is that if a machine can handle the hardest materials in large amounts, it can handle virtually anything. If the test returns unacceptable results, a machine is often removed from a manufacture’s vendor list, even though it may be suitable for many of its other products. But this typical process is flawed when sourcing basket mills for coatings dispersions because they excel at small batch production. Consequently, some manufacturers have the misconception that basket mills do not work well with hard-to-grind materials, and unfortunately they may end up purchasing a less-effective piece of equipment. The truth is quite the opposite. Basket mills offer easy operation, fast cleanup with little waste, repeatable performance and high production rates, while still providing high-quality grinding for coatings. Some of today’s designs have even addressed environmental concerns by reducing solvent emissions.
FIGURE 1 | Basket mill illustration.
The basket mill concept has improved since its introduction in the 1980s. New designs offer improved productivity and even finer dispersion quality. With these enhancements and the proper pilot testing, coatings manufacturers should be convinced that a basket mill can produce the ideal dispersion.
Basics of the Basket Mill Basket mills feature a rotating basket that uses centrifugal force to accelerate the grinding media, much like an amusement park ride where passengers lean against a wall while the ride rotates at high speeds. Unlike the ride, which merely locks passengers into place, the basket contains a disk installed with pegs to permit grinding. As illustrated in Figure 1, the top, bottom and sides of the basket are perforated to allow the product to enter. In the center of the basket the grinding disc attaches to a shaft that is centered in the basket drive shaft. This inner shaft is braked to prevent the disc from rotating with the beads and product. The sieve basket rotates around the fixed grinding disc. The basket is filled about 80 to 85 percent by volume with the grinding beads. When the basket rotates, the centrifugal force compresses the beads against the grinding disc. The shearing forces for dispersion are created between the fixed disc, the moving bead mass and the rotating basket. The blocks mounted to the top and bottom of the basket along with the grinding disc create turbulence for higher shearing force. In most cases, steel, glass or ceramic beads with a diameter of 1.2 mm for a smaller basket, and 2 mm for a larger basket, are best for coatings dispersions. However, bead size is ultimately determined by the basket’s slot sizes.
Updated Basket Mill Designs Basket mill design improvements have helped increase productivity and produce finer dispersion quality, with slot widths as small as 0.5 mm. The new design substanBy Harry Way | NETZSCH Fine Particle Technology, Fernandina Beach, FL 72
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Achieving Ideal Dispersions in Coatings The Case for Basket Mills
tially increases pumping rate and media compression performance. Increasing the pumping rate through the basket results in a higher re-circulating rate. This means that the batch volume passes through the basket more frequently, giving a narrower particle size distribution, or a cleaner grind. The
increase in pumping rate also eliminates settling problems that may occur in the process tank. Newer basket designs also increase the media compression zone. One downside to older designs was the basket’s size and shape. The basket was essentially a solid cylinder, large in diameter and narrow
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in height. Two problems could occur with this design. With very low-viscosity products, a high basket speed sometimes resulted in a vortex that entered only the periphery of the basket. This left the center of the basket empty and subject to high frictional heat, resulting in premature media wear and, in some cases, a dried fused media slug that would lock the basket against the stationary disc. The second problem was with viscous materials because they had the tendency to slide off the top and bottom plates, never entering the basket for dispersion. Updated designs leave the top and bottom plates solid. The hollow center of the basket uses centrifugal force, much like a centrifugal pump, to force the material through the grinding area (Figure 2). The material must pass through the grinding zone. The fixed rods attached to the fixed disc provide the turbulence necessary to create shear. This design allows a substantial increase in basket speed. Higher basket speed creates better circulating of the batch and higher compression of the media. Higher media compression results in a finer particle size distribution. If a large vortex is created, this no longer poses a problem, since the center of the basket is now empty of grinding media. Essentially the production rate of basket mills has doubled, and the ceiling of a 7 (12.5 microns) Hegman grind has been broken. Manufacturers can now produce off-scale grinds. The graph in Figure 3 illustrates production time versus grind quality for a typical product. For most products, these grinding results exceed a manufacturer’s typical expectations. Mills with a rotating basket are also more efficient than previously used sta-
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Achieving Ideal Dispersions in Coatings The Case for Basket Mills
FIGURE 2 | Updated basket mill design; the hollow center of the basket uses centrifugal force to force the material through the grinding area.
Stationary Shaft
Rotating Shaft
Stationary Disc
tionary baskets with a rotating rotor. If the basket is stationary, it is harder to clean. Another issue is that stationary designs use an open top to allow the product to enter the basket. This can lead to beads flowing out when the product viscosity is high. If the beads come out, the grinding efficiency is lost and the product must be filtered, adding an additional step. While the stationary design requires a special tank, a mill with a rotating basket is compatible with tanks already in use at the factory, which can reduce a manufacturer’s start-up costs. For harder-to-grind material, however, a tank with a cooling jacket is recommended to control temperature during dispersion. In the past, the production of solventborne products posed a large environmental concern for solvent emissions. New basket mill designs have greatly reduced this problem because there are no feed and discharge tanks requiring extra lids and no open flow discharge into a tank. To further prevent emissions, manufacturers should use a tank with a lid designed to allow the solvent vapors produced to condense and drip down the tank’s inner walls. This keeps the upper portion of the tank relatively clean.
Updated Design in Action Using NETZSCH’s most recent basket mill design, the TopMill, as an example, the steps for producing the ideal coatings dispersion are explained below.
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Achieving Ideal Dispersions in Coatings The Case for Basket Mills
FIGURE 3 | Production time versus grind quality for a typical production
FIGURE 4 | Basket TopMill illustration – product is drawn through the slots of the upper and under surface into the grinding zone and radially discharged.
Hegman Grind (Micron Scale)
batch. 105 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0
NETZSCH TM 10 TopMill 0.5 mm U-Basket Solventborne alkyd enamel base Drum Coating TiO2, PC Blue, Bentone 8,000 centipoise initial viscosity 3120 centipose final viscosity 35-gallon batch 520 RPM shaft speed 1 mm SAZ media
0
1
2
3
Stationary Shaft Rotating Shaft
4
Production Time (Hours)
Stationary Grinding Disc
Premixing: This is the first step for ideal coating dispersion. In fact, premixing is as important as any other milling operation. The product is premixed with a high-speed dissolver (HSD) as is done with all basket mills. Priming: The premixed batch is transported to the TopMill. The basket is lowered into the batch, and it is turned on and off for several cycles. During this process, air bubbles rise from the batch. Priming the batch and pre-grinding the solids is a very important step in de-aeration, preventing a foamy batch.
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Grinding: The basket is then turned on to maximum speed. A supplied Variable Frequency Drive (VFD) controls the speed of the basket with the maximum speed determined by power consumption or the vortex level. For example, on a 50 horsepower machine, the batch size can range from 45 gallons to 220 gallons. If a smaller batch size is run, the basket speed is slower. A larger batch size leads to a higher basket speed for faster production. In the end, about the same amount of time is required for both small and large batches – about one to four hours to reach a 7 Hegman grind. One concern may be that the material in the tank is not circulating through the basket. The basket operates as an impeller, much like a high-speed dissolver. The product flows in a vortex in the batch tank with the same characteristics of the HSD process (Figure 4). Higher-viscosity products are handled by adding pumping blades to the radius of the basket. After desired grind quality is achieved, the basket is raised from the batch. At this point the basket is rotated very briefly to spin or centrifuge the bulk of the remaining product from the basket. With this design, the batch yield is nearly 100 percent. This reduces the waste material and the cleaning required.
Conclusion Today’s basket mills have been re-developed to achieve optimal results in the coatings industry. Even the most difficult-to-grind materials can be processed in a basket mill, leading to high-qual-
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ity end products. When investigating new grinding equipment, manufacturers should look beyond trial results based on large batch sizes and consider basket mills for a clean, efficient and quality process, especially for smaller batch production. 䡲
“Innovative Silicone Technologies” The Silicone Elastomer Handbook
For more information, visit www.netzsch-grinding.com.
A guide to applied silicone elastomer technology
140 Hegman Grind Hours vs Temp. ºF
130 120 110
Milori (Iron) blue paint tint base 200-gallon batch 275 RPM shaft speed at start 450 RPM shaft speed after 2 hours 0.7-1.2 mm zirconium oxide media 104 KU (~2000 cps) viscosity at start No cooling water used
0
1 2 Production Time (Hours )
100 3
7 6 5 4
2 1
Hegman Grind (NS Scale)
7 6
15 30 45 Production Time (Minutes)
60
Available Now at: www.siliconehandbook.com - 369 pages
0
- 144 figures and tables - Extensive 27 page glossary
NETZSCH TopMILL TM 10 Solventborne alkyd enamel base 50% titanium dioxide 15% resin solids 1360 centipoise final viscosity 15-gallon batch 300 RPM shaft speed 1 mm SAZ media
- Property constants and conversion chart - Insightful chapters on property modification and troubleshooting
5 4 3
- Actual case histories to reinforce key technology facets
2 1 0
- A formulation guide 0
50 Hegman Grind (Micron Scale)
Also this book is expected to find utility in: - Academia as a text book - Libraries as a technology guide
8
3
8
Author David M. Brassard has taken his years of experience and compiled them into this useful guide to serve as an industry resource for applied silicone technology.
90
NETZSCH TopMill TM-8-10 HP drive U-basket Solventborne acrylic primer Titanium dioxide Strontium chromate Barium sulfate 35% pigment 6% resin solids 1380 cps final viscosity 15-gallon batch 300 RPM shaft speed 1 mm SAZ media
0
Based upon a course taught by the author at the Akron Polymer Training Center, College of Polymer Science and Polymer Engineering at the University of Akron.
150
NETZSCH TopMill TMC-50 - 50 HP DRIVE 0.5 mm U-Basket
Batch Temperature (°F)
7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0
Hegman Grind (NS Scale)
Fineness of Grind Gauge (Hegman Scale)
Appendix
15 30 45 Process Time (Minutes)
60
- Forward by Dr. Barry Arkles
NTZSCH TM-10 TopMill 0.5 mm U-basket Solventborne epoxy enamel base 50% titanium dioxide/wax 15% resin solids 1840 centipoise final viscosity 40-gallon batch 420 RPM shaft speed 1 mm SAZ media
45 40 35 30 25
www.siliconesolutions.com 1670-C Enterprise Pkwy. Twinsburg, Ohio 44087 Phone 330-405-4595 Fax 330-405-4596
20 15 10 5 0 0 15 30 45 60 75 90 105 120 135 150 165 180 Production Time (Minutes)
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Environmentally Compliant, Deflocculating W
Aqueous wetting/dispersing properties, wide range of operability and favorable cost/performance, despite their higher water sensitivity and foam stabilization. In an attempt to overcome these limitations, modern dispersing agents are based on high-molecular-weight acrylate or urethane polymers that offer enhanced steric stabilization and improved water sensitivity. However, sheer size of these molecules renders them ineffective wetting agents. The wealth of industrial experience dictates that efficient and homogeneous distribution of solid pigments is a key factor affecting the performance, stability and ultimate profitability of the paint formulation. In order to fully develop properties of pigmented dispersions and eliminate defects (i.e., flocculation, color shift, flooding, floating, leveling, settling), pigment agglomerates and aggregates are broken down to their fundamental particles and distributed homogeneously throughout the medium. This process usually consists of three fundamental steps:1,2 · wetting agglomerates by the medium; · separation of the pigment particles; and · stabilization of the pigment particles in the dispersed state preventing reagglomeration and flocculation.
D
Although fundamentally distinct, these stages are interrelated and largely overlap. Thus, wetting additives enable the wetting of pigment agglomerates and dispersing additives improve stabilization of the pigment dispersion. In reality, the same product can function as both. Such products adsorb onto the pigment surface and maintain proper pigment spacing through electrostatic repulsion or steric ue to the changing environmental cli-
mate as well as market initiatives, paint and coating formulators are being driven to develop more eco-sustainable products. This includes the reduction and/ or elimination of volatile organic compounds (VOCs) as well as alkyl phenol ethoxylates (APEOs) from coating formulations. APEO compounds have become less acceptable, due to the harmful effects of their degradation products on aquatic life forms and their potential effect on organism fertility. The latter considerations are mainly responsible for paint manufacturers and raw materials suppliers choosing to work with environmentally friendly materials, gradually phasing out, or banning outright, the use of APEO compounds, despite the absence of any legislative guidelines prohibiting their use. Alkyl phenol ethoxylates have found their way into a variety of industrial formulations due to their excellent
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TABLE 1 | Physical properties of Pluracoat® CF 20 surfactant. Characteristic Physical state and appearance Specific gravitya Viscosity,a cPs Pour point,b ºF Cloud point,c ºF Flash point,d ºF VOCe
Value Clear liquid at ambient temperatures; milky white paste at sub ambient temperatures 1.046 200 45 195 392 0
a
Property assessed at 23 °C. According to ASTM D 97. c Measured on 1 wt% aqueous solution. d Cleveland Open Cup method. e According to ASTM D 3960. b
By Dr. Elvira Stesikova, Development Leader; Gregory Drewno, Research Technical Specialist; Ronald Lee, Marketing Manager, Care Chemicals BASF, and John Kelly, Chemist; Dr. Jacob Wildeson, Research Chemist, Dispersions BASF | BASF Corporation, Florham Park, NJ APRIL 2010 | W W W . P C I M A G . C O M
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Wetting and Dispersing Agent for
Dispersions
Viscosity of Paint Dispersions Rheological evaluation is possibly the most common technique for assessment of pigment dispersant effectiveness in coating formulations. Tremendous reduction in viscosity is one indicator of dispersive power providing an analytical tool for comparative studies of various surfactants. For the purpose of this study, Pluracoat® Performa CF20 was compared against an industry-standard APEO-based (Octylphenol Ethoxylate, capped) color float/color acceptance additive (Sample A). This dispersant/wetting agent has been widely used in architectural and industrial coatings for improved color acceptance as well as imparting freeze/thaw stability. Despite the environmental pressure, Sample A remains an excellent benchmark due to its outstanding performance. Both additives were added to the paint dispersions at the same loading level of 3.5 lb/100 gal. Figure 1 and Table 2 present viscosity data obtained for flat and semi-gloss paint dispersions. Age stability test results (Figure 1) indicate that both surfactant additives are powerful and efficient dispersing agents that significantly reduce the viscosity and provide dispersion stability over the time range tested in this study. Table 2 data also indicate
TABLE 2 | Viscosity data of flat and semi-gloss paint formulations containing Sample A and Pluracoat® CF 20 dispersing additives, respectively, measured at 50 º C after 14 days of exposure (Heat Stability test). Paint Flat Semi-gloss
Dispersing Additive
Time (Days)
Viscosity (KU)
Sample A Pluracoat® CF 20 Sample A Pluracoat® CF 20
14 14 14 14
107 104 105 102
FIGURE 1 | Aging test performed on flat and SG paint formulations containing Sample A and Pluracoat® CF 20 dispersant agents. Viscosity is plotted as a function of time after introducing the dispersing additive. Flat paint Viscosity (cPs)
120 Viscosity (cPs)
hindrance. This reduces the tendency towards uncontrolled flocculation and agglomeration driven by the high surface energy and omnipresent van der Waals forces. Dispersing agents could simply be classified according to their chemical structure3 as anionic, cationic and nonionic. However, it is far more important to distinguish them based on whether the additives stabilize the deflocculated or flocculated state.4 In flocculated stabilization, the controlled flocculating wetting and dispersing additives form three-dimensional structures responsible for thixotropic behavior and improved sagging and settling, flooding and floating. On the other hand, deflocculating dispersing and wetting additives provide dispersions of small particles with Newtonian flow and lower viscosity, allowing high pigment loading. All these will result in high gloss, increased color strength and more efficient pigment utilization. Such additives are typically low-molecular-weight polymers that adsorb upon the pigment surface and stabilize deflocculated condition by steric hindrance. The main focus of this work was to develop a zero-VOC and APEO-free highly effective deflocculating wetting and dispersing agent with low foam and water sensitivity profile. Pluracoat® CF 20 is a nonionic deflocculation dispersing and wetting additive for water-based coating systems. It has been designed specifically to provide superior performance in wetting, dispersing and deflocculation of pigment particles and to comply with environmental regulations (Table 1).
110 100 90 80 0
2
3
4
5
Time (Days)
6
7
110 100 90
Sample A Pluracoat® CF 20
1
Semi-gloss paint
120
8
80 0
Sample A Pluracoat® CF 20
1
2
3
5
6
7
8
that both dispersing agents provide excellent heat stability, since the paint viscosities remain mainly unchanged after 14 days of exposure to 50 °C. Both dispersing additives provided comparable stabilization effect on the paint formulations. No significant differences were observed between the Sample A and Pluracoat® CF 20 formulations.
Freeze/Thaw Stability Freeze/thaw stability test results, depicted in Figure 2 for the semi-gloss formulation, suggest very good compatibility of Pluracoat® CF 20 with the paint formulation and its comparable performance with Sample A. In fact, the overall rise in viscosity after five freeze/thaw cycles was only 5.0 and 5.5 KU for Sample A and Pluracoat® CF 20 containing dispersions, respectively. Note that the same paint, free of dispersing additive, failed this test. This fact suggests that Pluracoat® CF 20 is indeed a very effective deflocculating dispersing additive.
Adhesion Adhesion results obtained for the flat and semi-gloss dispersion systems tested in this study are listed in Table 3. Based on the results, it is evident that the choice of the dispersing agent did not have a significant effect on the adhesion properties. Both dispersing agents revealed excellent adhesion. PA I N T & C O A T I N G S I N D U S T R Y
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Time (Days)
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Environmentally Compliant, Deflocculating Wetting and Dispersing Agent for Aqueous Dispersions
Water Resistance Water resistance of the resultant coatings is one of the primary formulating concerns when selecting surfactants and additives for performance optimization. Water resistance data for the flat and semi-gloss formulations tested in this study are presented in Table 4. As evident by the data, Pluracoat® CF 20 not only matched the performance of the Sample A additive, but it also decreased the water uptake of the coating by 15% in flat and 6% in semi-gloss formulations. These very encouraging results should provide additional flexibility to the paint formulators when balancing performance and stability attributes of the complex coating systems.
Pigment Dispersion and Color Evaluation In addition to dispersion stability tested by rheology and freeze/thaw stability, efficiency of pigment utilization is best revealed by color development testing. The performance of Pluracoat® CF 20 was evaluated relative to that
FIGURE 2 | Viscosity of a semi-gloss paint formulation containing Sample A (circle symbols) and Pluracoat® CF 20 (square symbols) measured after each freeze/thaw cycle. 110
KU Viscosity (cPs)
105
100
95 Sample A Pluracoat® CF 20 90
0
1
2
3
4
5
6
Freeze/Thaw Cycles
TABLE 3 | Adhesion results for the flat and semi-gloss paint dispersions containing different dispersing additives. Surfactant
Flat Paint SG Paint Dry Wet Scrub Dry Wet Scrub Adhesion Adhesion Resistance Adhesion Adhesion Resistance
Sample A
5
5
2190
5
5
2540
Pluracoat® CF 20
5
5
2200
5
5
2530
TABLE 4 | Water resistance of the flat and semi-gloss coating formulations containing different dispersing additives measured as % water uptake by 20 mil dried coating submerged in water for 24 hours. Surfactant Sample A Pluracoat® CF 20
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Flat Paint
SG Paint
8.91 7.61
22.28 21.08
of Sample A dispersing additive. Tables 5 and 6 present color development data for Universal Red organic colorant in flat and semi-gloss formulations, respectively. In the flat paint dispersion formulation, tint strength of the Pluracoat® CF 20-containing system matches that of Sample A. The ∆E between the two additives is negligibly small, i.e., 0.08. The hiding power K-∆E values are 0.18 and 0.25 for Sample A and Pluracoat® CF 20 respectively, and are well below the 1.0 acceptable standard. The Rub Out coefficients (RO) have small negative values indicating small if not insignificant pigment float to the surface of the coating.5 Furthermore, ∆E measurement between rubbed and unrubbed coating areas, listed in Table 5 as ∆E(RO), confirm that the changes caused by sheer forces are only marginal. In semi-gloss paint dispersions, the tint strength of the Pluracoat® CF 20-containing system differs from that of Sample A by 0.8. This could partly be interpreted as a slight improvement of the dispersing power of Pluracoat® CF 20 and partly could be attributed to the accuracy of the measurement. The ∆E between the two additives is also negligibly small, i.e., 0.1, indicating once again a match of pigment dispersing powers of the additives. The hiding power K-∆E values are 0.09 and 0.18 for Sample A and Pluracoat® CF 20 respectively, well below the 1.0 acceptable standard. The RO results have positive values, 2.10 and 1.36, indicating TiO2 float to the surface of the coating.5 Despite the relatively large RO values, ∆E measurement between rubbed and unrubbed coating areas, listed in Table 6 as ∆E(RO), indicate that visual changes are small and not significant, since ∆E values remain well below 1.0. The touch-up test, and specifically low-temperature touch-up, has been designed to mimic real life application conditions. Albeit being a poor predictor of actual performance of the formulation, this remains one of the most challenging tests to pass. Typical touch-up test consists of two coating applications over a period of 24 hours. After allowing a first layer to cure overnight, the second coating is applied partially overlapping the first one. The color readings are taken to compare the areas coated with one and two layers. Some variations of this method could be adopted allowing one or both layers to be applied and cured at low temperatures. The results of these tests, conducted for semi-gloss paint at room temperature (RT) and low temperature (LT) conditions, are presented in Table 7. The results of the touch-up study indicate that pigment dispersion properties are equally well developed in the presence of either Sample A or Pluracoat® CF 20. Thus, when the first and second layer of coating are applied at the same condition (first set of data at RT and second set of data at LT), the ∆E and Tint Strength (CREL) results show no difference between one and two layer coating. However, when the first layer was applied at RT followed by the second coat at LT, a slight increase in ∆E (up to 0.22) is accompanied by reduction of tint strength (down to 98.4 and 98.5). While this is a clear performance limitation, both Sample A and Pluracoat® CF 20 exhibit similar behavior, indicative of fundamental formulation issues rather than issues related to the dispersing additive.
APRIL 2010 | W W W . P C I M A G . C O M
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Environmentally Compliant, Deflocculating Wetting and Dispersing Agent for Aqueous Dispersions
TABLE 5 | Color evaluation results, using an X-Rite spectrophotometer, for the flat paint formulation containing different dispersant agents. Note that Sample A containing paint dispersion was used as a control. Surfactant Sample A Pluracoat® CF 20
TS
DE
K-DE
RO
DE (RO)
100 99.6
0 0.08
0.18 0.25
-0.20 -0.36
0.25 0.22
TABLE 6 | Color evaluation results, using an X-Rite spectrophotometer, for the semigloss paint formulation containing different dispersant agents. Note that Sample A containing paint dispersion was used as a control. Surfactant
TS
Sample A 100 Pluracoat® CF 20 100.8
DE
K-DE
RO
DE (RO)
Gloss 20º
Gloss 60º
0 0.1
0.09 0.15
2.10 1.36
0.51 0.52
16.2 15.7
53.7 53.0
TABLE 7 | Touch up test results for semi-gloss paint dispersions containing different dispersing additives.
Conclusion Pluracoat® CF 20 was developed as an effective and environmentally compliant deflocculating dispersing and wetting additive. This zero-VOC and alkyl phenol-free surfactant has proven to perform as a suitable replacement for Sample A in a number of aqueous-based dispersant formulations with an added benefit of improved water sensitivity. As a multifunctional additive, Pluracoat® CF 20 allows the preparation of stable aqueous dispersions, providing a good opportunity to reformulate existing platforms to comply with low/zero-VOC regulations and alkyl phenol ethoxylate-free requirements. 䡲
References 1
2
3
System Sample A RT Pluracoat® CF20 RT Sample A LT Pluracoat® CF20 LT Sample A LT Pluracoat® CF20 LT
Control
DE*
CREL
Sample A RT Pluracoat® CF20 RT Sample A LT Pluracoat® CF20 LT Sample A RT Pluracoat® CF20 RT
0 0.18 0 0.18 0.22 0.22
100 100.8 100 100.9 98.4 98.5
4 5
Patton, T.C. Paint Flow and Pigment Dispersion; Wiley Interscience Publication, 1979. Doren, K.; Freitag, W.; Stoye, D. Waterborne Coatings; Hanser Publishers, 1994. Swarp, S.; Schoff, C.K. Progress in Organic Coatings 1993, 23, 1-22. Scholtz, W. De Verfkroniek, vol 71, 1998, p 33-36. Kaluza, U. Physical/Chemical Fundamentals of Pigment Processing for Paints and Painting Inks, Edition Lack und Chemie, 1981.
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Chain Extender Evaluation for Polyurethanes Derived f
Polybutadiene
C
hain extenders play a significant role in enhancing the final mechanical properties of polyurethanes derived from hydroxylterminated polybutadiene (HTPB) and 4,4´-methylenebis(phenyl isocyanate) (MDI). Conventionally, N,N-diisopropanol aniline (DIPA) and 2-ethyl-1,3-hexanediol (EHD) are recommended for their compatibility and physical property enhancement of the polyurethane elastomer. By comparison, 1,4-butanediol (BDO), widely employed in polyurethanes based on polyether or polyester polyols, is not a good choice owing to its poor compatibility with HTPB resins. A systematic screening of both aromatic and aliphatic diols as potential chain extenders in standard HTPB-based polyurethane formulations has been carried out. Although a good correlation could not be drawn between the diol structure and mechanical performance, two new aliphatic diols were notable for their superior performance.
many chain extenders designed for polyether or polyester polyols were proven to be unsuitable for the HTPB-derived polyurethanes. The poor compatibility between the chain extenders and the non-polar nature of the polybutadiene backbone was attributed to be the root cause. Two types of HTPB resins are available commercially. Poly bd® resins are radically polymerized products, having about 2.5 hydroxyl functionalities.4 Krasol® LBH and LBH-P polybutadiene diols are anionically polymerized products with a very narrow molecular-weight distribution, each containing no species with a functionality higher than 2.0.4,6 We have shown in previous publications that 2-ethyl-1,3-hexanediol and N,N-diisopropanol aniline (Voranol® 220-530) were excellent chain extenders1,5 for the polyurethanes derived from either Poly bd or Krasol resins. Because of recurring supply issues, we initiated a search for alternative chain extenders suitable for the polyurethane system based on HTPB resins. This report describes our preliminary findings.
Introduction Polyurethanes based on polybutadiene polyols are known for excellent hydrophobicity, hydrolytic and chemical resistance, electrical insulation properties, and low-temperature flexibility.1-3 Similar to other polyurethanes, the gum stock formulations based on neat HTPBs and stoichiometric amounts of diisocyanates usually possess inferior mechanical properties. Incorporating chain extenders, such as diols of low molecular weight, in the gum stock formulas enhances the elastomeric properties of the resulting polyurethanes, because the small diols react with diisocyanates and form hard domains to serve as the physical crosslink for the polyurethane systems. Traditionally, 1, 4-butanediol is one of the most important chain extenders used in commercial polyurethane elastomers based on polyether or polyester polyols. Since HTPBs have a completely non-polar backbone structure,
TABLE 1 | Compatibility of aromatic chain extenders (CE) with Krasol LBH 2000 resin. Wt Ratio of CE / LBH- 2000
Chemical Name 1,3-bis(2-hydroxy ethoxy) benzene, (HER™ HP) Hydroquinone bis(2hydroxyethyl) ether N-phenyldiethanolamine
3.2/10.0 3.2/10.0 3.0/10.0
Miscibility and Solubility @ 23 °C
@ 110 °C
Two phases Two liquid phases (liquid, solid) Two phases Two phases (liquid, solid) (liquid, solid) Two phases Two liquid phases (liquid, solid)
Experimental Materials Poly bd and Krasol resins were obtained from Cray Valley USA, LLC. Chain extenders 2-ethyl-1,3-hexanediol (EHD), 1,3-butanediol (1,3-BG), 2-butyl-2-ethyl-1,3-propanediol (BEPG), and 2,4-diethyl-1,5-pentanediol (PD-9) were sampled from Kyowa Hakko U.S.A. Inc. Hydroquinone bis(2-hydroxyethyl) ether, N-phenyldiethanolamine, 4,4´-methylenebis(phenyl isocyanate) (MDI), dibutyltin dilaurate (DBTDL), 1,6-hexanediol, and 2,2,4-trimethyl1,3-pentanediol (TMPD) were purchased from Aldrich. HER™ HP, i.e., resorcinol di(β-hydroxyethyl)ether was kindly given to us by Indspec Chemical Corporation. All the materials were used in the reaction as is without further purification.
Preparation of Polyurethanes – Lab Procedure One-Shot Procedure Krasol LBH-2000 resin was added to a four-necked resin kettle, followed by degassing and dehydrating at 85 ºC in vacuo (<10 mm Hg) for 1.5 h. Diisocyanate MDI flakes and solid chain extenders (CE) were melted in an oven right before usage. Liquid Krasol resin, MDI, CE, and DBTDL catalyst were then charged to a centrifuge cup. The mixture was homogenized in a SpeedMixer™ (model DAC 150), then poured onto a hot metal mold. The sample was initially cured in an oven at 110 ºC for 3.5 h, and then at
By Herbert Chao and Nan Tian | Cray Valley USA, LLC, Exton, PA 86
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d from Hydroxyl-Terminated
Resins Results and Discussion
65 ºC overnight. The sample was further aged one week at room temperature to ensure complete curing before physical property testing was performed.
A few diols of low molecular weight, including aromatic and aliphatic types, were selected as potential chain extenders. Examining the compatibility of the diols with HTPB resins at various temperatures serves as the initial screening before incorporating them in polyurethane formulations. Two preparative procedures, namely, oneshot and prepolymer, were used to make the polyurethane sheets. The hard domain contents in the polyurethane sheets were set at 30, 35, 40 and 45% for monitoring the concentration effect of the chain extenders on physical properties. As to HTPB resins, both Krasol LBH 2000 and Poly bd R45HTLO resin were examined.
Prepolymer Procedure MDI flakes were charged to a four-necked resin kettle. The kettle was heated with stirring to melt the MDI under nitrogen. To the kettle containing liquid MDI was added warm (65 ºC) Krasol LBH 2000 resin. The reaction was held at 75 ºC for 1.5 h to form the prepolymer, which was then degassed at 75 ºC in vacuo. The prepolymer, liquid CE, and DBTDL catalyst were then charged to a centrifuge cup. The mixture was homogenized in a SpeedMixer (model DAC 150), then poured onto a hot metal mold. The sample was initially cured in an oven at 110 ºC for 3.5 h, and then at 65 ºC overnight. The sample was further aged one week at room temperature to ensure complete curing before the testing of physical properties was performed.
TABLE 2 | Compatibility of aliphatic chain extenders (CE) with Krasol LBH 2000 resin. Chemical Name 1,6-hexanediol 2,2,4-trimethyl-1, 3-pentanediol (TMPD) 2-ethyl-1,3-hexanediol (EHD)
Characterization and Testing An Instron Materials Tester (model 4301) was used for measuring the physical properties of polyurethane sheets at 22.2 °C (72 ºF) and 60% relative humidity. Tensile strength, elongation and modulus (at 50% strain) were obtained by following the ASTM D 412 protocol. Tear strength was determined by following the ASTM D 624 protocol. For each sample four or five specimens were tested and an average value reported. Sample hardness was determined with a Round Shore Durometer Type A or Type D at room temperature.
1,3-butanediol (1,3-BG) 2-butyl-2-ethyl-1,3propanediol (BEPG) 2,4-diethyl-1,5pentanediol (PD-9)
Miscibility and Solubility
Wt Ratio of CE / LBH- 2000
@ 23 °C
@ 110 °C
3.0/10.0
Two layers
Two layers
3.2/10.0
Soluble
Soluble
Any ratio
Soluble
Soluble
2.0/10.0 3.0/10.0 3.0/10.0
Intensely cloudy Partial BEPG crystallized Cloudy, heterogeneous
Cloudy Clear, homogeneous Lightly cloudy, no separation
TABLE 3 | Krasol resin-derived polyurethanes having 30% hard domain contents. Krasol LBH 2000L, g 2-ethyl-1,3-hexanediol, g 2-butyl-2-ethyl-1,3-propanediol, g 2,2,4-trimethyl-1,3-pentanediol, g 4,4´-methylene bis(phenyl isocyanate), g 20% DBTDL solution in dibutyl phthalate(DBP), drop(s) Hard segment content, wt.% Equivalent ratio of LBH/MDI/chain extender
1
2
3
4
5
6
100 11.69 -----31.11 2 29.97 1/2.8/1.8
100 --12.45 --30.56 1 30.08 1/2.75/1.75
100 ----11.46 31.14 2 29.87 1/2.7/1.7
100 11.69 -----31.11 1 29.97 1/2.8/1.8
100 --12.45 --30.56 2 30.08 1/2.75/1.75
100 ----11.46 31.14 2 29.87 1/2.7/1,7
Procedure in Synthesis Physical Property Hardness (shore A) at 23 °C Tensile strength, psi Modulus, psi Elongation at break, % Tear resistance, Ibf/in
One Shot 79 1106 438 216 308
79 1300 434 315 305
Prepolymer 80 1650 418 511 313
82 2139 518 440 334
80 2147 491 465 312
79 1263 404 553 283
PA I N T & C O A T I N G S I N D U S T R Y
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Chain Extender Evaluation for Polyurethanes Derived from Hydroxyl-Terminated Polybutadiene Resins
TABLE 4 | Polybd resin-derived polyurethanes having 30% hard domain contents. Polybd R45 HTLO, g 2-ethyl-1,3-hexanediol, g 2-butyl-2-ethyl-1,3-propanediol, g 2,2,4-trimethyl-1,3-pentanediol, g Isonate 143L 20% DBTDL solution in DBP, drop(s) Hard segment content, wt.% Equivalent ratio of R45HTLO / Isonate143L / CE
1
2
3
100 11.62 ------32.86 3 30.31 1 / 2.75/1.75
100 ---11.30 ---32.27 4 30.34 1/2.7/1.7
100 ------10.62 32.86 3 30.31 1/ 2.75/1.75
Procedure in Synthesis Physical Property Hardness (shore A) at 23 °C Tensile strength, psi Modulus, psi Elongation at break, % Tear resistance, Ibf/in
4
One Shot 81 946 450 195 213
79 874 425 197 203
5
6
100 100 100 11.62 ----------11.30 --------10.62 32.86 32.27 32.86 2 1 1 30.31 30.34 30.31 1 / 2.75/1.75 1/2.7/1.7 1/ 2.75/1.75
Prepolymer 80 868 458 181 191
79 844 449 177 189
78 712 355 193 142
81 809 454 164 175
TABLE 5 | Krasol resin-derived polyurethanes having 45% hard domain contents. Krasol LBH 2000L, g 2-ethyl-1,3-hexanediol, g 2-butyl-2-ethyl-1,3-propanediol, g 2,2,4-trimethyl-1,3-pentanediol, g 4,4´-methylene bis(phenyl isocyanate), g 20% DBTDL solution in DBP, drop(s) Hard segment content, wt.% Equivalent ratio of LBH/MDI/chain extender
1
2
3
4
5
6
100 26.30 -----56.11 3 45.20 1/5.05/4.05
100 --27.75 --54.45 3 45.12 1/4.9/3.9
100 ----26.28 56.51 2 45.29 1/4.9/3.9
100 26.30 -----56.11 3 45.20 1/5.05/4.05
100 --27.75 --54.45 3 45.12 1/4.9/3.9
100 ----26.28 56.51 1 45.29 1/ 4.9/3.9
Procedure in Synthesis Physical Property Hardness (shore A) at 23 °C Tensile strength, psi Modulus, psi Elongation at break, % Tear resistance, Ibf/in
One Shot 91 2153 1104 179 429
Aromatic Diols as Chain Extenders The compatibility of the aromatic chain extenders with Krasol LBH 2000 resin was evaluated and the results are listed in Table 1. It is conceivable that the aromatic chain extenders selected have extremely poor compatibility with the Krasol resin. We managed to evaluate 1,3-bis(2hydroxy ethoxy) benzene and N-phenyldiethanolamine in a prepolymer procedure, hoping that pre-reacting of the diols with MDI would mitigate the compatibility issue. Unfortunately, with the 30%, 35% and 40% hard domain contents, the polyurethanes derived from both chain extenders were inferior to the controls containing EHD. Thus, they were not evaluated further.
Aliphatic Diols as Chain Extenders The aliphatic diol candidates were chosen based on their commercial availability and significant hydrocarbon moiety in the molecules. They were submitted for compatibility testing with Krasol LBH 2000 resin and the results are listed in Table 2. There is no strong distinction based on compatibility to favor any one chain extender over the others. Thus, they were all tested in the polyurethane formulations. 88
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Prepolymer 94 2181 1439 173 535
95 3503 1565 351 534
96 3458 1512 365 544
95 2999 1702 368 572
The chain extender 1,6-hexanediol turned out to be too incompatible with the Krasol resin in the one-shot process. The approach was abandoned. Similarly, the chain extenders 1,3-butanediol and PD-9 yielded parts of low hardness, tensile strength and modulus compared with those made using EHD in the one-shot process. Although the prepolymer procedure in general mitigated the compatibility issue to a certain degree, the polyurethane parts made by using 1,6-hexanediol, 1,3-butanediol or PD-9 were still not on a par with the materials containing EHD. On the other hand, the chain extenders TMPD and BEPG yielded excellent polyurethane parts with the hard domain contents ranging from 30 to 45%. The formulations and physical properties of the polyurethanes having hard domain contents of 30% are listed in Tables 3 and 4, which employ Krasol LBH 2000 and Poly bd R45HTLO resin, respectively, along with three outstanding chain extenders. Since the polyurethanes derived from Krasol resin and 4,4’-MDI should be thermoplastic in nature (Table 3), they have better elongation, tear resistance and tensile strength than those crosslinked polyurethanes derived from Poly bd resin and
APRIL 2010 | W W W . P C I M A G . C O M
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Chain Extender Evaluation for Polyurethanes Derived from Hydroxyl-Terminated Polybutadiene Resins
Isonate 143L (Table 4). However, the differences in physical properties between those derived from Krasol and Poly bd resin (Tables 5 and 6, respectively) are not as significant when the hard domain contents reach 45%. Based on the limited examples above, it is noted that the good chain extenders, namely, EHD, BEPG, and TMPD
are completely soluble in HTPB resins (Table 1). The solubility criterion seems to be a necessary condition for the chain extenders to have before further examining the mechanical properties of the polyurethanes derived from them and HTPB resins. Needless to say, the molecular weight of the chain extenders cannot be excessively large
TABLE 6 | Polybd resin-derived polyurethanes having 45% hard domain contents. Polybd R45 HTLO, g 2-ethyl-1,3-hexanediol, g 2-butyl-2-ethyl-1,3-propanediol, g 2,2,4-trimethyl-1,3-pentanediol, g Isonate 143L 20% DBTDL solution in DBP, drop(s) Hard segment content, wt.% Equivalent ratio of R45HTLO / Isonate143L / CE
1
2
3
4
5
6
100 23.67 ------58.56 4 45.12 1 / 4.9 / 3.9
100 ---23.36 ---57.96 4 44.94 1/4.85/3.85
100 ------23.67 58.56 4 45.12 1/ 4.9 / 3.9
100 23.67 ------58.56 1 45.12 1 / 4.9 / 3.9
100 ---23.36 ---57.96 1 44.94 1/4.85/3.85
100 ------23.67 58.56 1 45.12 1/ 4.9 / 3.9
Procedure in Synthesis Physical Property
One Shot
Hardness (shore A) at 23 °C Tensile strength, psi Modulus, psi Elongation at break, % Tear resistance, Ibf/in
95 2617 1384 216 422
96 2780 1427 246 431
Prepolymer 97 3326 1565 290 487
92 - 93 3032 1500 271 446
96 – 97 2622 1385 235 450
96 - 97 2580 1406 238 465
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Chain Extender Evaluation for Polyurethanes Derived from Hydroxyl-Terminated Polybutadiene Resins
to disrupt the hard domain formation through hydrogen bonding. Interestingly, EHD was found not to be a suitable chain extender any longer when HTPB resins were blended with polyether polyols, such as polypropylene glycol (PPG) and polytetramethylene glycol (PTMEG), to make polyurethane copolymers. BDO turned
out to be outstanding again in those polyol blends.5 Similarly, BDO is a better chain extender than EHD for the polyurethane block copolymers derived from HTPB and polyester polyols7 regarding the mechanical properties enhancements. Physical properties are noted in the charts in Appendix 1.
Conclusions In addition to the two classic chain extenders, namely, N,N-diisopropanol aniline and 2-ethyl-1,3-hexanediol, recommended for the polyurethane systems derived from hydroxyl-terminated polybutadienes, two more aliphatic diols are identified through extensive testing for the same utility. These two new chain extenders, 2-butyl-2-ethyl1,3-propanediol and 2,2,4-trimethyl-1,3pentanediol are not only miscible with hydroxyl-terminated polybutadienes, but also enhance the mechanical properties in the HTPB-derived polyurethanes, as well as the benchmark 2-ethyl-1,3-hexanediol chain extender. 䡲
References 1
2
3
4
5
6
7
“Sartomer Products for Urethane Elastomers,” Sartomer Technical Bulletin No. 1560, Sartomer Co., 08/05. Pytela, J.; Sufcak, M.; Cermak, J.; Drobny, J.G. “Novel Isocyanate Prepolymers Based on Polybutadiene Diols for Composite Binders and Cast Elastomers,” Proceedings of the Polyurethanes, 1998, EXPO98, Dallas, September 1998, pp. 563 Pytela, J.; Sufcak, M. “PolybutadieneUrethane Elastomers with Outstanding Resistance to Aggressive Aqueous Media,” UTECH 2000 Conference, The Hague, The Netherlands, March 2000. Conference Proceedings, Coatings, Adhesives, Sealants and Elastomers Session, Paper 9. “Hydroxyl Terminated Polybutadiene Resins and Derivatives - Poly bd and Krasol,” Sartomer Technical Bulletin No. 3151, Sartomer Co., 06/07. Chao, H. S.; Pytela, J.; Tian, N.; Murphy, J. “Thermoplastic Polyurethanes (TPUs) Derived from Hydroxyl-Terminated Polybutadienes (Krasol®)” API 2005 Polyurethanes Technical Conference and Trade Fair, October 17-19, 2005. Pytela J.; Sufcak, M. “New Anionic Polybutadiene Diols for Polyurethane Systems,” Proceedings of the Polyurethanes World Congress 1997, Amsterdam, The Netherlands, September 1997, pp. 704. Chao, H. S.; Tian, N. “Preparation and Property Evaluation of Thermoplastic Polyurethanes (TPUs) Based on Polybutadiene and Polyester Polyols” Polyurethanes 2007 Technical Conference, September 24-26, 2007.
For more information, contact
[email protected]. This paper was presented at Polyurethanes 2009 Technical Conference in Fort Washington, MD on behalf of the Center for the Polyurethanes Industry (CPI).
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Appendix 1: Physical Properties
90 85 80 75 70
30 35 40 45
300 200
30 35 40 45
3000 2500 2000 1500 1000 500 0
100
Prepolymer EHD BEPG TMPD
90 85 80 75
30 35 40 45
30 35 40 45
One-Shot
EHD BEPG TMPD
1200 1000 800 600
Tensile Strength (psi)
Modulus (psi)
1400
Elongation at Break (%)
Prepolymer EHD BEPG TMPD
250 200 150
200 100
30 35 40 45
30 35 40 45
Hard Segment (%)
Prepolymer
One-Shot
Prepolymer
3500 500
EHD BEPG TMPD
3000 2500 2000 1500
0 30 35 40 45
Hard Segment (%)
One-Shot
300
600
500
300
EHD BEPG TMPD
4000
200
Elongation at Break of Polyurethanes from New Chain Extenders and Polybd Resin
400
Tear Resistance of Polyurethanes from New Chain Extenders and Krasol Resin
1000
30 35 40 45
Prepolymer
Tensile Strength of Polyurethanes from New Chain Extenders and Krasol Resin
400
30 35 40 45
One-Shot
500
0
30 35 40 45
One-Shot
1600
30 35 40 45
Hard Segment (%)
EHD BEPG TMPD
400 300 200 100 0
30 35 40 45
30 35 40 45
Hard Segment (%)
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100 50
30 35 40 45
30 35 40 45
Hard Segment (%)
94
600
Hard Segment (%)
Prepolymer
30 35 40 45
Elongation at Break of Polyurethanes from New Chain Extenders and Krasol Resin
70 30 35 40 45
Modulus of Polyurethanes from New Chain Extenders and Polybd Resin
0
EHD BEPG TMPD
30 35 40 45
Hard Segment (%)
Prepolymer
One-Shot
95
Hard Segment (%)
0
0
30 35 40 45
Hardness of Polyurethanes from New Chain Extenders and Krasol Resin Shore A Hardness at 25 ºC
Tensile Strength (psi)
One-Shot
1000
Hard Segment (%)
Tensile Strength of Polyurethanes from New Chain Extenders and Polybd Resin
Prepolymer EHD BEPG TMPD
1500
0
30 35 40 45
One-Shot
500
100
Hard Segment (%)
3500
EHD BEPG TMPD
400
2000
Prepolymer
One-Shot
Elongation at Break (%)
EHD BEPG TMPD
500
Tear Resistance (lbs/in)
Shore A Hardness at 25 ºC
95
Prepolymer
Tear Resistance (lbs/in)
One-Shot
100
Modulus of Polyurethanes from New Chain Extenders and Krasol Resin
Tear Resistance of Polyurethanes from New Chain Extenders and Polybd Resin
Modulus (psi)
Hardness of Polyurethanes from New Chain Extenders and Polybd Resin
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And, much more!
APRIL 2010 | W W W . P C I M A G . C O M
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Chemical Legislation Panic or Practicality?
I
have been formulating adhesives and coatings since 1956, and in those years have seen government policies and regulations change entire industries, some justifiably, others not so justifiably.
Historical Perspective In the early years, some adhesives and most coatings had to meet severe fire-retardance tests. Adhesives, being sandwiched between two substrates, and therefore having less exposed surface, were faced with far fewer and less stringent restrictions than coatings. Flame-retardant additives were, for the most part, expensive, calling for judicious use of the products, using just enough to meet the requirements. In those years, Monsanto had a marvelous chlorinated resin/plasticizer/fire retardant series trade named Arochlor. Available in both liquid and solid forms, covering a multitude of melting points and a broad range of chlorine contents, these resins imparted flame retardance to a host of varied products. Soluble in many organic solvents, they could be added directly to solvent systems. They could also be emulsified for addition to water-based systems. Formulations could be modified with these resins to meet the most stringent test requirements. Distillation, an important procedure in the course of the manufacture of each Arochlor resin, resulted in a dark, residual, high chlorine content still bottom as a by product requiring disposal. For years, these still bottoms
were buried at various sites, until someone decided to market them as cheap, chlorinated fire-retardant resins. They could be coupled with asphalt to make low-cost, fire-retardant roof coatings, whereas previous efforts to fire retard inexpensive asphalts were cost prohibitive. Suddenly, the still bottoms became a series of marketable products rather than a landfill. These became the Montar series of resins. Those of you in the industry at the time probably recall the publicity surrounding the sudden, mysterious decline in the peregrine falcon population. Apparently, something was responsible for the incomplete formation of the falcon eggshells, leaving them thin and extremely vulnerable to breakage. This was ultimately traced to residual quantities of these chlorinated resins. These were the polychlorinated biphenyls and polychlorinated polyphenyls that became so notorious under the general designation PCBs. When they were withdrawn from the marketplace, they left a tremendous void, which formulators found difficult to fill.
Filling the Fire-Retardant Gap One product that appeared to be a reasonable candidate to fill the void was Firemaster T23P, from Michigan Chemical Corporation. This excellent fire retardant was so good, in fact, that it was used to flame retard textiles, some of which were used in the manufacture of children’s pajamas. As a result of some dermatological reactions, a ques-
By Jerome B. Marks, Ph.D., Technical Director | General Plastics Corporation, Bloomfield, NJ 96
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Chemical Legislation
tion arose as to the possible carcinogenicity of T23P. Some of you may remember the “Tris” fiasco, which resulted in yet another flame retarding compound being removed from the marketplace. Antimony oxide coupled with chlorinated hydrocarbon resins is, to a great extent, filling the void … for now.
Other Legislative Efforts/Effects Paints and other exterior coatings were, for years, color matched to the recognized standards of the various companies whose plants and manufacturing sites they adorned. Lead and chromate pigments which, among others, gave the formulator the versatility of color matching coatings to any desired shade, were deemed hazardous and removed from the market. Mercurial preservatives, the most effective fungicides and bactericides in the world, were viewed as being hazardous, and were, therefore, removed from the marketplace. Their replacements initially resulted in inferior end products, with higher raw material costs. We can go back as far as 1966, when Los Angeles enacted Rule 66 and San Francisco passed Regulation 3. Both severely limited the use of “photoreactive” solvents, such as xylene, in adhesives and coatings in order to reduce smog generation. Then came a major trend going from products in “dangerous, highly flammable” solvents such as hexane, acetone and toluene to the “safer” nonflammable chlorinated solvents. In that span of time, the legal, Department of Transportation definition of a “flammable liquid”, i.e., one requiring the red, diamond shaped “Flammable Liquid” warning label, went from one having less than an 80 °F flash point to one having less than a 100 °F flash point. To add to the confusion, IATA (International Air Transport Association) regulations define a flammable liquid as one having a flash point below 140 °F. Today, the cry is for the elimination of ODS (ozone-depleting solvents) such as 1,1,1-trichloroethane and the “toxic/carcinogenic” chlorinated solvents such as methylene chloride. Then came the mother of them all … asbestos. As a raw material in adhesives and coatings, asbestos was unique. It is flame retardant, acid and alkali resistant, weather resistant, it is an insulation, a thixotrope, a film reinforcer and … it was CHEAP. For decades asbestos was used in adhesives and coatings in a multitude of applications from mobile home roofs 98
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to ceramic tile adhesives. It was also used in automotive brake linings, as building insulation, in high-temperature protective gloves and fire-protective clothing. In short, it found a place in virtually every industry. In 1962, Dr. Irving Selikoff, Director of the Environmental Services Laboratory at the Mt. Sinai School of Medicine in New York, was hired by New York Local 12 and Newark Local 32, International Association of Heat and Frost Insulators and Asbestos Workers’ Union to examine the overabundance of asbestos-related illnesses in union members. Dr. Selikoff found an apparent link between asbestos exposure and the incidence of lung cancer, asbestosis and mesothelioma. Although asbestos was a primary raw material in the products of such prestigious organizations as National Starch, GAF, PPG, 3M, HB Fuller, etc., the panic resulting from Dr. Selikoff’s report fomented government legislation that placed the entire asbestos industry in jeopardy. The fact that the large majority of these cases stemmed from overexposure to the dense fogs of airborne asbestos fibers so common in the World War II shipyards of 20 years prior, did absolutely nothing to mitigate the general panic and concern regarding asbestos. Rather, it fostered a whole new, highly regulated, exceptionally lucrative industry … asbestos abatement.
OSHA In 1970, the Williams Steiger Act was passed into law. This ultimately became the Occupational Safety and Health Act (OSHA). Under OSHA requirements, employers must maintain a complete and accurate Material Safety Data Sheet (MSDS) for each hazardous material that is used in the facility. The MSDS is a detailed information bulletin prepared by the manufacturer, which describes the physical and chemical properties, physical and health hazards, routes of entry, precautions for safe handling and use, emergency and first aid procedures and control and disposal methods, for each product. An MSDS must accompany each shipment of hazardous or potentially hazardous material. OSHA 174, preceded by OSHA Form 20, is a simple, easy-to-read and understand two-page affair. Although OSHA specifies the information to be included in an MSDS, it does not prescribe the precise format. The result has been completely worthless and totally incomprehensible 20- and 30-page documents, serving no purpose other than to comply with the letter of the law. In no possible way could a police officer, confronted with a spill of a hazardous substance, quickly and easily take the necessary emergency measures to reduce the hazard by reading the MSDS accompanying the shipment. He wouldn’t be able to locate the pertinent information, let alone comprehend it. This is very definitely self-protective overkill sponsored by government legislation. Something would certainly appear to be very wrong with government legislation when it is easier to purchase an assault weapon than it is to buy a few drops of cyclamate to sweeten your coffee. 䡲 Comments may be directed to Dr. Marks at
[email protected].
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P RODUCTS 䡲 Oven PRECISION QUINCY: Model EC-415-6TCDIF has an overhead trolley conveyor support that enables long parts to be loaded into the oven by manually pushing the conveyor trolley. Once loaded, the operator closes the heavy-duty doors on the oven entrance end. When curing is complete, double doors on the exit end are opened to pass through the finished parts. This Class A oven is custom designed and optimized for powder curing of long pieces of aluminum extrusions. The interior working space on this model is 360 cubic feet with an anticipated operating temperature of 375 °F and a maximum temperature of 450 °F. Visit www.precisionquincy.com.
䡲 Mixer CHARLES ROSS & SON CO.: The In-line SLIM does not require a pump or eductor, thereby lowering operation and maintenance costs. The unique rotor/stator generator in this system includes progressive spiral porting, which produces high flow, high shear and a high level of vacuum within the rotor/stator generator. This
enables the system to operate without a pump and induct powders at unprecedented rates, resulting in shorter mixing cycles, an immediate lump-free dispersion of the powders, improved endproduct quality and a safer working environment by eliminating “dusting” in the plant. Visit www.highshearmixers.com.
䡲 Additive BYK ADDITIVES & INSTRUMENTS: ANT-TERRA®-250 offers superb stabilization of fillers and inorganic pigments, resulting in good color acceptance and low-E values in the coating system. Floating and flooding of these pigments is prevented and, due to the thixotropy effect, settling and sagging in aqueous systems is avoided. It is recommended for water-reducible primers, emulsion paints and floorings. Free of solvents and with a high solids content, it improves flow and leveling, especially in waterborne self-leveling flooring based on epoxy resins. Visit www.byk.com.
䡲 Container PLASTICAN INC.: The 36BR is a 4.25-gallon rectangular plastic container designed to provide better cube efficiency and volume packaging. Rigid yet lightweight, these containers tolerate a wide temperature range. They also offer easy handling and excellent stacking strength. Produced using high-density polyethylene or propylene, these pails score high on environmental sustainability scorecards. Hinged lids are available, are easily resealed and feature a tamper-evident tear strip. Bi-directional handle options allow better ergonomics. Visit www.plastican.com.
䡲 Heating Element PROCESS TECHNOLOGY: The CE-certified quartz infrared heating elements offer a heavy-wall quartz sheath. They are available in sizes 500-4000 watts and in a variety of voltages, including 120, 208 and 240. Ceramic insulators provide positive electrical insulation. The elements are used for curing, baking and drying applications and are capable of reaching full heat in 40 to 65 seconds. With watt densities of 50 watts per square inch, the elements contain long-life nickel chrome resistance wire. E-mail
[email protected].
䡲 Mixer SPX: Nettco i-Series portable and fixed-mount mixers satisfy a wide range of mixing and mounting requirements, utilizing a distinctive modular assembly design. Multiple mounting configurations include clamp style, open tank or sealed designs for maximum flexibility. The mixer design can be quickly converted from one mounting arrangement to another in as little as two minutes. Visit www.lightninmixers.com.
䡲 Specialty Chemical
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DOW: ECHELON™ MU 290 specialty isocyanate is a uretoniminemodified MDI-based solution for adhesives, sealants, elastomers and coatings applications. With improved shelf life and reduced
APRIL 2010 | W W W . P C I M A G . C O M
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P RODUCTS
emissions, it has good compatibility for mixing. It offers improved clarity for the creation of products with lighter color requirements and can be used for the production of quasi and full prepolymers, and two-component urethane coatings, adhesives, sealants, and solid and microcellular elastomers. A liquid product, it offers improved shelf life and low-temperature flexibility and can be stored economically and conveniently at room temperature. Visit www.dowechelon.com.
The aqueous solution of actives will not contribute to the VOC of the product preserved and contains no formaldehyde. It is demonstrated as an in-can preservation system for water-based paint and coatings systems, aqueous polymer emulsions and latex systems, adhesives,
and sealants. The preservative may be added at any point in the production cycle. E-mail
[email protected].
䡲 Carbon Black
CABOT CORP.: EMPEROR 1800 provides high black color performance, rapid and
䡲 Resin
DSM POWDER COATING RESINS : Uralac® P 3220 gives excellent durability in a wide range of colors at lower curing temperatures with improved blanching performance and heat resistance. This polyester resin offers an all-in-one solution for curing: low temperature, fast curing, excellent flow and non-blooming. Visit www.dsmpowdercoatingresins.com.
䡲 Media Mill
NETZSCH FINE PARTICLE TECHNOLOGY: The updated ZETA RS is equipped with an advanced media separation system and improved mechanical seal system that allow the mill to handle the smallest grinding media and enable the mill to grind particles as small as 50 nm. It also meets requirements for comminution down to the nano range using the mild dispersion process, which protects the desired properties of the material. With a new tilting-chamber feature that allows easier loading and unloading of grinding media, it is available in four chamber sizes, ranging from two liters to 25. Visit http://grinding-netzsch.com.
䡲 Rheology Modifier
COGNIS: DSX 3291 is an associative thickener for “green” water-based coatings. An excellent pseudo-plastic viscosity builder, it is up to five times more efficient than conventional products. It is easy to handle, can be incorporated into coating formulations with low shear power, and enables thick coatings to be easily sprayed. It is suitable for all types of paints, including premium flat and eggshell, semi-gloss, and gloss coatings. Visit www.cognis.com.
䡲 Preservative
ISP PERFORMANCE CHEMICALS : Nuosept ® BMc 422 is a broad-spectrum preservative that is active against microbes, bacteria and fungi at use levels ranging from 0.05-0.5 percent by weight.
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Selecting the best Additives is Child’s Play
P RODUCTS
Serving the Paint and Coatings Industry with innovative silicone additives for better flow, leveling, slip, mar resistance, and foam control. Innovative Silicones for your Technology
Manufacturer of organo modified & reactive silicones. SILTECH CORPORATION 225 Wicksteed Avenue, Toronto, Ontario, Canada, M4H 1G5 Tel: (416) 424-4567 Fax: (416) 424-3158 www.siltechcorp.com
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JBW Systems has manufactured high-quality, mixing equipment for drums and totes for over 18 years – proving that it is possible to have superior mixing at an affordable cost.
economical dispersion, and long-term performance stability. Consisting of small-particle carbon black that is chemically modified in order to attach specific functional groups to the pigment surface, it is fully compatible with waterborne systems and delivers better performance than conventional oxidized carbon black pigments. It disperses quickly. As a result, grinding times are shortened and the quantity of dispersion additives required to achieve optimum performance can be considerably reduced. E-mail
[email protected].
䡲 Catalog BROOKFIELD ENGINEERING LABORATORIES: This 2010 full-color catalog features a new powder flow tester that delivers quick and easy analysis of powder flow behavior in industrial processing equipment. Also included are: DV-II+Pro EXTRA, a viscometer that delivers time savings and superior performance in the lab; EZ-Lock spindle coupling kits; the Falling Ball viscometer, an instrument that provides dynamic viscosity measurement of transparent Newtonian fluids; and the RS Portable Rheometer, which operates in the lab, on the production floor or in the field with a rechargeable battery. Visit www.brookfieldengineering.
Fluorosurfactant CHEMGUARD: S-764P fluorosurfactant is a VOC-free, short-chain (C6), phosphate-ester-based product ideal for use in VOC-free coatings, floor polishes and inks. Its surface activity rivals competitive longer-chain perfluoro products now on the market, with no need to increase concentrations to obtain similar results. Chloridefree and available as an easy-to-use liquid, it provides numerous benefits in paint, adhesives, metal plating, waxes and polishes. E-mail
[email protected].
䡲 Balance The JBW Line of Patented Conical, Turbine Impellers for Drums, Totes® and Lift Systems
JBW Systems, Inc. (614) 882-5008 www.jbwsystems.com
To learn more about our innovative mixing equipment – call JBW Systems today.
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APRIL 2010 | W W W . P C I M A G . C O M
PAUL N. GARDNER CO., INC.: FX-iWP is the first waterproof and dustproof, 0.001 g, compact precision balance. It incorporates a reduced-size, compact, super-hybrid sensor that provides quick (one-second) readings with high precision. The new statistical calculation function provides statistical data display or output of weighed samples. Visit www.gardco.com. 䡲
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