Paint & Coatings Industry 2010,06

V IEWPOINT They Are All Great Issues! You know each issue of PCI that we finish I think is the best one – until the nex...

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V IEWPOINT

They Are All Great Issues! You know each issue of PCI that we finish I think is the best one – until the next month. I am always so pleased with the features, the new technology and all of the technological changes I see in the industry – particularly when you have been around a while you can look back and see significant change over time. I have the advantage of reading a great number of submitted papers and company literature each day, and it is always exciting. Tremendous technology is used within a coating that the average person on the street has no idea about. There are significant formulation differences between an interior house paint and an aircraft coating that must withstand extreme temperature and flexibility/expansion changes in a short time frame. Or the auto paint that must have that showroom finish and be expected to always appear that way – or the marine paint that is exposed to salt water and hot sun but better not fade or peel. And those are but a very, very few examples. Each of the main components of the coating is important, and sometimes the smallest amounts – the additives – are the most important of all.

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If we could print the entire PCI issue this month it would be almost 200 pages long. That is because of the Additives Handbook – which is dear to me, being one of the co-authors. Back when I first joined the coatings industry, there were limited resources for technical and instructional coatings information. Most of us coming into this industry needed basic education – we had good backgrounds in chemistry or other sciences but most were not trained in coatings. So we were hungry to learn – but available print information was lean. We learned on the job from experienced formulators and plant personnel in the companies. We had no internet to search, but we did have a few journals to read, and we had a basic monograph series on various aspects of coatings (called the Federation Series on Coatings Technology), which was printed by people of knowledge who were members of the FSCT. Most of these were published prior to the 1970s and a few in the early ‘70s. We would have been happy to have a source like the current Additives Handbook, which is a compilation of the additives used in the industry, along with descriptions of each. This was simply not available back then. Several years ago, when we first put the Handbook together, it was easier to do than it is today, as additives fit nicely into defined categories. With the movement toward waterborne and other low-VOC technologies, however, the world of additives is rapidly changing. Many additives today are part of the polymer itself, and so many additives are multifunctional, making it difficult to categorize. The advent of nanotechnology has added another dimension to the world of additives. Because of new technology and the importance of all of our features we chose to print just a few pages of the Additives Handbook definitions so that we would be able to provide you, our readers, with the latest in new technology via the features. The Handbook may be found in its entirety on our website, www.pcimag.com. Also, it is highly recommended you purchase the CD of the complete Additives Handbook by contacting Andrea Kropp directly at [email protected]. As always we have updated the Handbook with the best available current information we have regarding the multitude of additives used in the coatings industry. This is an extensive compilation, and the CD is of great benefit to all formulators, manufacturers and applicators of coatings, in addition to resource centers such as libraries and educational facilities. Many ‘seniors’ in the industry have remarked how beneficial this tool would have been when they first joined the industry years ago – and I for one wholeheartedly agree. Also, be sure to read the liquid glass coating technology article this month (page 24). The liquid glass attributes have resulted in the coating being regarded as one of the most important surface coating technologies to have emerged in recent years. And this is why I always get excited and it never gets old!!

By Darlene Brezinski, Ph.D. / Editor

JUNE 2010 | W W W . P C I M A G . C O M

5/24/10 8:51:51 AM

I NDUSTRY NEWS

Architectural Paint Demand to Reach 22.8 Million Metric Tons CLEVELAND – World demand for architectural paint is forecast to rise 3.6 percent per year through 2013 to 22.8 million metric tons, valued at $51 billion. Growth will slow in comparison to the performance of the 2003 to 2008 period due to a deceleration in global building construction growth through 2013. Gains will nevertheless remain strong by long-term historical standards. These and other trends are presented in World Architectural Paint, a new study from The Freedonia Group Inc., a Clevelandbased industry research firm. As was the case over the past decade, the most rapid gains will arise in the world’s emerging markets, most prominently in Asia. Gains in Asia are based primarily on continued healthy expansion in the large Chinese and Indian markets. Although Japan is projected to post

gains that will significantly lag behind the global average through 2013, the country’s architectural paint market will see a reversal of the declines experienced during the 1998-2008 period. North America will post slightly aboveaverage gains through 2013. Going forward, the housing and mortgage crisis

Additives Consumption Study Released ELMWOOD PARK, NJ – According to Global Coating & Ink Additives, a new study by the consulting firm Kusumgar, Nerlfi & Growney, consumption of the five leading additives for coatings and inks was 1.72 billion pounds, worth $3.47 billion, in 2009. Volume was down 10 percent compared to 2008, with North American and European usage down the most. Additive consumption in the Asia-Pacific region was off a more modest three percent, as growth in China and India partially offset the declines in Japan and South Korea. A five percent annual rate of growth is forecast for global additive consumption through 2014. Rheology modifiers are the leading additive type with 39 percent of the 2009 dollars. Cellulosics, water-based synthetics, fumed silicas and organoclays are the leading rheology modifiers. Foam-control additives edged out dispersants for second in value in 2009 with the bulk used in water-based paints. Dispersants were 17 percent of the dollars and range from highly specialized polymeric types to higher-volume polyacrylic acid varieties for architectural paints. Slip-and-rub additives were fourth in value and are comprised of wax products and silicones. Wetting agents were 11 percent of the volume and 12 percent of the value in 2009.

New Numerical Algorithms Available for Researchers OXFORD, UK – Paint and coatings researchers can now download the new NAG Library for SMP and Multi-core from Numerical Algorithms Group (NAG). The NAG Library for SMP and Multi-core contains over 1600 routines, including over 100 new routines for this release. A 8

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that has plagued the United States since 2006 will subside, providing opportunities for paint sales to the new-homes market. Moreover, sales to the much larger home repainting segment will also benefit as sales of existing homes improve, because existing homes are often repainted when they are to be sold. In 2008, Western Europe accounted for 21 percent of total architectural paint demand. Western Europe’s share of the global market will continue to slip as the region registers weak gains, due to belowaverage economic and building-construction-expenditure growth, mortgagesector weaknesses in some constituent nations, and stagnant regional population gains. Nevertheless, Western Europe will remain the world’s leading regional net exporter of architectural paint, due largely to the presence of Germany.

complete listing of these routines can be found at www.nag.com/ numeric/fl/FSdescription.asp.

Hydraulic Institute Seeks Reviewers PARSIPPANY, NJ – The Hydraulic Institute (HI), under the approval of the American National Standards Institute (ANSI), is seeking qualified individuals in North America to participate in the review process for the draft of updated standards ANSI/HI 10.1-10.5 AirOperated Pumps for Nomenclature, Definitions, Application and Operation and ANSI/HI 10.6 Air-Operated Pump Tests. Individuals and organizations located in North America directly and materially affected by these standards are asked to contact HI. To participate, e-mail Karen Anderson at [email protected].

New EPA Rules Regarding Lead Paint Now in Effect WASHINGTON – As of April 22, 2010, the U.S. Environmental Protection Agency requires that renovations and repairs of pre-1978 housing must now be conducted using safe practices to protect children and pregnant women from exposure to lead-based paint. The Lead Renovation, Repair and Painting Rule requires contractors to be trained and certified in lead-safe work practices. The new rule requires that renovation firms must be certified by the EPA, individuals must be trained in lead-safe work practices, and that all those providing training must be EPA accredited.

SME Calls for Award Nominations DEARBORN, MI – The Society of Manufacturing Engineers (SME) is issuing its annual call for nominations for the 2011 International Honor Awards, the Outstanding Young Manufacturing Engineer


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I NDUSTRY NEWS OBITUARY Industry Loses K. Hiroshi Fujimoto

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,

WEST BLOOMFIELD, MI – K. Hiroshi (Hiro) Fujimoto, 87, of Naples, FL, and West Bloomfield, MI, died on Thursday, April 8, 2010, at Avow Hospice. Fujimoto is survived by his wife, Christine Arnott-Fujimoto, three children, three stepchildren and nine grandchildren, as well as a brother and sister. Fujimoto worked with ASTM for many years, including serving as the Subcommittee Chair of Committee D01.21, Analysis of Whole Paints and Paint Materials. He was recognized for his work with ASTM, receiving the John C. Weaver Excellence in Leadership Award in 2002, the Henry A. Gardner Subcommittee Chairman of the Year Award in 1982, the Award of Merit in 1987. and the Award of Appreciation in 2009.

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. Formulators choose Sartomer for UV/EB innovation and consistent quality… batch after batch. Our broad line of more than 700 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.

FREE New Product Alert E-Mails

Register at www.sartomer.com/home.asp

Award and the Award of Merit. The deadline to submit nominations for awards is August 1, 2010. Nomination forms can be downloaded from sme.org/awards.

North Dakota State University Offers Short Courses FARGO, ND – The Department of Coatings & Polymeric Materials at North Dakota State University is now accepting registrations for its annual short courses. The Fundamentals of Coatings Science Short Course is designed for all levels of scientists and technologists working in the field of coatings. The course will take place June 6-11, 2010. The Corrosion Protection by Coatings: Testing and Lifetime Prediction course will be a practical guide to the corrosion process, characterization of corrosion, corrosion protection by coatings and testing of coatings. The course will take place June 13-15, 2010. For additional information, visit www.ndsu.edu/ cpm/shortcourse.

Date Change for CHINACOAT 2010


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GUANGZHOU, China – CHINACOAT 2010, which was originally scheduled to take place Dec. 1-3, 2010, will now take place Sept. 27-29, 2010. The event will be held in Guangzhou, China, at the Guangzhou International Convention and Exhibition Center. For more information about the show, visit www.chinacoat.net. 䡲


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C ALENDAR Meetings, Shows and Educational Programs JUNE 13-15

JULY 4-10

Corrosion Protection by Coatings: Testing and Lifetime Prediction www.ndsu.edu/cpm/shortcourse

International Conference on Composites/Nano Engineering http://myweb.polyu.edu. hk/~mmktlau/ICCE/ICCE_ Main.htm

22 Ci4000/Ci5000 Weather-Ometer Workshop www.atlas-mts.com 22-25 A&WMA Annual Conference & Exhibition www.awma.org 23 Fundamentals of Weathering Level I www.atlas-mts.com 23-24 Asia Pacific Coatings Show www.coatings-group.com 24 Fundamentals of Weathering Level II www.atlas-mts.com

19-21 Coatings for People in the General Industry, Sales & Marketing http://coatings.mst.edu 19-23 Polymers and Coatings Introductory Short Course www.polymerscoatings. calpoly.edu

SEPT. 8-10

26-29 2010 SSCT Annual Meeting http://ssct.org 27-29 CHINACOAT 2010 www.chinacoat.net 28 Ci4000/Ci5000 Weather-Ometer Workshop www.atlas-mts.com 29 Fundamentals of Weathering Level I www.atlas-mts.com 30 Fundamentals of Weathering Level II www.atlas-mts.com

Spray Finishing Technology Workshop www.owens.edu

OCT. 3-5

9-10 Korean Coatings Show www.coatings-group.com

4-6 Radiation Curing Technology www.pra-world.com

ASC Fall Convention www.ascouncil.org

5-6 Coatings Trends and Technologies www.bnpevents.com/PCI/CTT 11-13 UTECH North America www.utechnorthamerica.nl 11-13 Polyurethanes 2010 Technical Conference www.americanchemistry.com 12-13 Wood Coatings Congress www.pra-world.com 12-14 COROSAVE www.corosave.com

Find On-Demand Webinars at webinars.pcimag.com

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7/17/08 10:08:44 AM


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C O M PA NY NEWS

PPG Opens Color Design Studio PITTSBURGH – PPG Industries’ industrial coatings business has opened the Shmaze Color Design Studio sponsored by PPG Trendcast. The facility, near Irvine, CA, is devoted to helping manufacturers and industrial designers accelerate color design and prototype development. “This new facility enables manufacturers and industrial designers from around the world to come into our workshop and walk out with production-ready parts and coatings that can run almost anywhere in the world,” said Richard Zoulek, PPG General Manager for Strategic Markets. “For design-intensive

organizations like consumer-electronics companies, that process can take threeto-six months due to logistical challenges. When you work with PPG, it can be reduced to days.”

Michael Shamassian, Principal of the Shmaze Color Design Studio, said the facility’s core mission is problem solving. “We have a full-service production line with robots, tooling, molders and other equipment that enables us to work through production and quality issues in real time, and to prove the viability of a coating in a matter of hours or days.” The Shmaze Color Design Studio was created to serve manufacturers and industrial designers in industries such as consumer electronics, automotive parts and accessories, beauty products, appliances, sports and recreation equipment, and aerospace.

VELOX to Distribute for PCC Rokita

AkzoNobel Increases Capacity in China

HAMBURG, Germany – PCC Rokita’s Polyol business unit (Poland) has signed an agreement with Hamburg-based raw materials distribution and sales specialist VELOX for the distribution of Rokopol® in France, Hungary, Czech Republic and Slovakia. Rokopol is the trade name of a wide range of polyether polyols.

AMSTERDAM, The Netherlands – AkzoNobel has announced the plant expansion for the manufacture of monochloroacetic acid (MCA) in China. The company’s Taixing site, which now boasts production capacity of 60,000 metric tons per year, will help to meet steadily increasing demand for MCA in China, where the market is growing in line with GDP at more than 10 percent annually.

Arkema Emulsion Systems Expands Customer Service Offerings CARY, NC – Arkema Emulsion Systems has announced the expansion of dedicated customer service capabilities at its Cary, NC, headquarters. The expansion includes the addition of four trained representatives who will work with customers to answer general product-related questions, assist in delivering specific product technical support and accept orders for the company’s full line of emulsion polymers. For general customer inquiries, call 866/837.5532.

Union Process Expands Presence in China AKRON, OH – Union Process has moved its China operation into a larger facility. The company purchased an existing complex in the downtown area of Qingdao, China. The facility consists of one structure for manufacturing and an adjoining structure that houses the testing lab, pilot plant, storage area and office space.

Zeeospheres Ceramics Recognizes Ribelin Sales LOCKPORT, LA – Zeeospheres Ceramics LLC, Lockport, LA, has recognized Ribelin Sales Inc., Garland, TX, as its Top Distributor for Sales in 2009. Ribelin represents Zeeospheres Ceramics’ portfolio of highstrength spherical microsphere fillers in Florida, Georgia, Alabama, South Carolina, North Carolina, Tennessee, Mississippi, Louisiana, Texas, Oklahoma, Arkansas, New Mexico, Nevada, Utah, Colorado and Arizona with stocking locations in Atlanta, Orlando, Houston, Dallas and Denver. 14

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LyondellBasell Emerges From Chapter 11 ROTTERDAM, The Netherlands – LyondellBasell has emerged from Chapter 11 bankruptcy protection. A new parent company, LyondellBasell Industries N.V., incorporated in the Netherlands, is the successor of the former parent company, LyondellBasell Industries AF S.C.A. LyondellBasell Industries N.V. owns and operates substantially the same businesses as the previous parent company, including subsidiaries that were not involved in the bankruptcy cases.

BASF Expands in China SHANGHAI, CHINA – BASF is establishing a new Polyurethane Solutions System House in western China. The new system house will be located in Chongqing, where BASF also plans to build a MDI plant. It will have local production with sales, technical service and development personnel and will start its first services by 2012. BASF has also inaugurated a new section of its Technical Competence Center for intermediates at its Shanghai Pudong site.

Bayer MaterialScience Listed by MPI PITTSBURGH – Bayer MaterialScience LLC is one of the first raw materials suppliers to get on board the Master Painters Institute® Inc.’s (MPI) Starting Point Program. Results of the MPI testing are as follows: the guide formula based on Bayhydrol® UH 2593/1 polyurethane dispersion passed


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C O M PA NY NEWS MPI 128, the guide formula based on Bayhydrol AH XP 2741 acrylic dispersion passed MPI 129, and the guide formula based on Bayhydrol UH 2557 polyurethane dispersion passed MPI 197. The Starting Point Program helps coating raw materials suppliers accelerate acceptance of resin or additive technologies by providing verification that formulations meet MPI’s highest performance standards.

Rio Tinto Minerals Extends Fitz Chem’s Territory

DSM and Berliner Glas Reach Licensing Agreement

MALVERN, UK – Malvern Instruments Limited has acquired certain assets of Swedish rheology company Reologica Instruments AB, Lund, Sweden. The purchase gives Malvern access to additional technologies and intellectual properties.

HEERLEN, The Netherlands – DSM Functional Coatings B.V., part of Royal DSM N.V., and Berliner Glas KGaA, a European supplier of refined technical glass, have agreed to the terms of a licensing deal for DSM’s anti-reflective coating system, KhepriCoat™. Berliner Glas intends to use KhepriCoat to improve the performance of its glass in lighting-cover applications.

ITASCA, IL – Rio Tinto Minerals (RTM) has expanded Fitz Chem Corp.’s territory, adding Minnesota, North Dakota and South Dakota. Fitz Chem now represents RTM’s talc business in these states plus all or part of Illinois, Iowa, Wisconsin, Indiana and Michigan.

Malvern Acquires Assets of Reologica Instruments

Evonik Acquires Methacrylate Specialty Esters Business ESSSEN, Germany – Evonik Industries has acquired Arkema’s Methacrylate Specialty Esters business. With this acquisi-

tion, Evonik enhances its competence in the Performance Polymers business unit as a specialist in methacrylate chemistry. The acquisition includes the following products: 2-ethylhexyl methacrylate (2-EHMA), dimethylaminoethyl methacrylate (MADAME), and n- and i-butyl methacrylate (n-BUMA and i-BUMA). The products will be integrated into the VISIOMER® sales range for methacrylate monomers, which comprises more than 50 monomers. The product VISIOMER DMAEMA will be marketed under the name VISIOMER MADAME™ in the future.

Cognis Sells UV Acrylates Business MONHEIM, Germany – Cognis has signed an agreement to sell its UV Acrylates business to IGM Resins B.V., based in Waalwijk, The Netherlands. The UV Acrylates business manufactures and sells monomers and oligomers for UV applications marketed under the Photomer brand name.

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Brilliant Solutions! Look to Brilliant Additions to achieve a real competitive advantage. Formulators use these versatile functional fillers to add performance and value without compromising cost targets. Meaningful cost savings are possible with higher loading rates, improved production efficiencies and rationalized raw materials inventories.

N AMES IN THE NEWS 䡲 Herman Benecke, a scientist for Battelle, has been chosen to receive the 2010 Industrial Uses of Soybean Oil Award by the American Oil Chemists’ Society. Since 1980, Benecke has been awarded 14 patents, many of which deal with the use of soybean and other vegetable oils to formulate products varying from flexible and rigid foams to more environmentally friendly and healthier plasticizers. 䡲 Guardian Protective Coatings has appointed Boyd Cooray Technical Director. Cooray is currently Director of Technology and New Business Development at Druckfarben Hellas in Greece. 䡲 NETZSCH Fine Particle Technology LLC has expanded Chris Esterly’s sales territory. Esterly will now support NETZSCH customers in Delaware, Maryland, New Jersey, Pennsylvania, Virginia and western parts of New York. NETZSCH has also designated a new Manufacturing Representative, Mitch Perlstein from Technika, to serve customers in the New England states.

䡲 Denise Kingstrom Fernandez has been appointed Strategic Accounts Manager for BASF Automotive Refinish and assumes responsibility for managing its ColorSource program. Keith Bell has been appointed Central Bell Kaufman Zone Manager. Bell will focus on growing the BASF Refinish business in the central United States. Michael Kaufman has been appointed Eastern Zone Manager. Prior to this, Kaufman managed the southeast zone for BASF Automotive Refinish, and Kingstrom Fernandez Moreau his role has been expanded to include the entire East Coast from Maine to Florida. John Moreau will rejoin BASF as Western Zone Manager. Jim Smith has been appointed Strategic Initiatives Manager. In this new role, Smith is responsible for implementing major initiatives within BASF Automotive Refinish.

䡲 John C. Husband has been designated as one of nine TAPPI Fellows for 2010. He currently serves as Lead Scientist for IMERYS Minerals Ltd., Cornwall, UK. 䡲 Thomas Langill, Technical Director at the American Galvaniz-

For more information and our complete product portfolio visit:

www.BrilliantAdditions.com

ers Association in Centennial, CO, has been elected Chairman of ASTM International Committee A05 on Metallic-Coated Iron and Steel Products. John Fletcher, Technical Support Manager at Elcometer Ltd. in Manchester, England, has been named Chairman of ASTM International Committee D01 on Paint and Related Coatings, Materials and Applications.

䡲 Evonik Industries has announced that Dietmar Wewers will SPECIALTY AND PERFORMANCE MINERALS

All rights reserved. ©2010

succeed Jochen Rosenau as the new head of the Coating & Adhesive Resins business line. Ralf Düssel will take over from Martin Welp as head of the Adhesive Resins product line. 䡲


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P RODUCTS 䡲 Powder Checker

DEFELSKO CORP.: The PosiTector PC powder checker measures uncured powder coatings using ultrasonic technology to automatically calculate and display a predicted cured thickness. New technology allows measurement on small tubes, odd shapes and moving parts. Features include an internal memory of up to 1,000 readings. Visit www.defelsko.com

䡲 Automated Control Package

MORSE MANUFACTURING CO., INC.: An advanced automated control package for Morse Tilt-To-Load drum rotators features automated drum lifting, rotating for operator-set time and return of drum to upright position at floor level. A safety

interlock on heavy-duty enclosure automatically shuts down the rotator if the gate is opened. Users can set rotation time anywhere from a few seconds to 99 hours. Visit www.MORSEmfgco.com

recirculating blower providing combination airflow; safety equipment for handling flammable solvents; and inner and outer door gaskets. E-mail [email protected]

䡲 Wax Emulsion

䡲 Mixer

emulsion is a sacrificial anti-graffiti coating additive that also provides effective water repellency and anti-blocking. It is commonly used as a surface modifier in concrete coatings to reduce or eliminate concrete’s susceptibility to damage caused by weather, equipment, vehicles or foot traffic. Visit www.michelman.com

tary PowerMix Model PD-100 features a lowspeed planetary stirrer with a conventional high-speed disperser. Both agitators revolve on their own axis while at the same time on a common axis. The high-speed blade provides an internal shearing action, while the planetary stirrer continually moves material into the high-speed blade. E-mail [email protected]

MICHELMAN: Michem Emulsion 47950 wax

䡲 Oven

THE GRIEVE CORP.: This walk-in oven is used for heat treating and curing paint and varnish. Features include: a maximum operating temperature of 1100 °F; 9’ x 9’ x 9’ work space dimensions; 240 KW installed in Incoloy-sheathed tubular heating elements; 24,500 CFM, 20 HP

K-KAT XK-622 Vs. DBTDL Air Dry Tack-free Times K-KAT XK-622

Set to touch, hours*

3

2.5

Surface dry, hours**

5.7

5.1

*Time when paint stops flowing into the scribed channel. ** Time when the recorder’s teflon stylus no longer leaves a clear channel, but begins to rupture the dry upper layer of the curing film.

Film Hardness & Gloss (30 minutes at 80°, Cure Schedule) DBTDL

K-KAT XK-622

20° Gloss, %

95.4

99.3

60° Gloss, %

100

100

Pendulum Hardness, cycles (initial)

44

50

Pendulum Hardness, cycles (3 days)

78

84

NEW K-KAT® XK-622

CELANESE EMULSION POLYMERS: EcoVAE® 405 and EcoVAE 408 are extremely low-odor, APE-free vinyl acetate/ethylene resins with low residual-monomer levels and the ability to formulate low- to nearzero VOC coatings. With greater durability,

Catalyst for Solventborne 2K PU Coatings

Comparison: 2K PU SB Acrylic Clearcoat

DBTDL

䡲 Emulsions

NEW K-KAT® XK-622

®

Circular recorder

CHARLES ROSS AND SON CO.: The Sani-

A Friendly Alternative to Tin Catalysts x

Offering equivalent or improved performance over DBTDL*

x

Good pot life

x

Quicker tack-free time

x

Faster hardness development

x

Excellent hardness and gloss Request additional information today by: Emailing: [email protected] or Calling: 203-866-5551

* Performance can be system/formulation specific

www.kingindustries.com


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P RODUCTS EcoVAE 405 allows formulators to develop products for use in tough environments such as kitchens and playrooms where frequent washing occurs. EcoVAE 408 was designed to be formulated into freezethaw-stable paints for contractors and DIY consumers in cold climates. Visit www.celanese.com

䡲 LED Lights

LARSON ELECTRONICS: Combining bright light output, color temperature control and five-year bulb life, these explosion-proof LED lights for paint spray booths are available in four-foot and twofoot lengths. With a UL Class 1 Division 1 and Class 2 Division 1 rating, these lights offer more light output than high-output fluorescent alternatives but with lower electricity usage and 5.5-year bulb life. Visit www.magnalight.com

䡲 Silica Aerogel

CABOT: Nanogel® aerogel for insulative coatings formulations is created through

a closed-loop process with little to no impact on the environment. Benefits include: long shelf life with consistent performance, formulation flexibility, rheology control, dispersion stability, density reduction, carrier for functional actives, nontoxic and sustainable, low-VOC formulations enabled, sag resistance, and low loading. Visit www.cabot-corp.com

䡲 Curative

COGNIS: Versamine® S 23 meets the need for benzyl alcohol, nonylphenol and bisphenol-A-free curatives with conventional or plural-component spray capability and that have excellent coating performance properties. It is designed to be used as a stand-alone curing agent due to its rapid cure response. Epoxy coatings based on Versamine S 23 have excellent chemical resistance properties. Visit www.cognis.com

䡲 Biocide

INTERNATIONAL SPECIALTY PRODUCTS INC.: Nuosept W Concentrate is a broad-spectrum preservative that combines the antimicrobial effects of CIT/MIT and Bronopol at higher concentrations than other commercial offerings. Typical use levels for the preservation of adhesives, tackifiers, coatings and detergents range from 0.0250.1 percent by weight. It will not contribute to the VOC of the product preserved and does not contain a formaldehyde donor. E-mail [email protected]

䡲 Polyester Resin

REICHHOLD INC.: AROFLINT® 810 is a polyester resin designed for high-performance 2K polyester-epoxy systems where excellent appearance, durability and toughness are required. When combined with AROFLINT® 608 epoxy resin, this nonisocyanate system has improved dry and hardness development and performance comparable to a 2K urethane. Visit www.reichhold.com 䡲

SUPPLIER SHOWCASES

MACE Polymers & Additives, Inc. The Polyurethane Specialists New Ownership / A World of Possibilities

䡲 “Green” PUD’s – Zero nMP & Zero VOC 䡲 Nano-Engineered PUD’s - for Improved Performance 䡲 Anti-Graffiti Coatings – Zero nMP 䡲 Fire Retardant PU Dispersions – Halogen Free 䡲 Functional PU Films for Thermoforming Applications Contact Ernie Gulla at 1-888-205-8126 or via email at: [email protected] Dudley, MA • Phone: 508-943-9052 • www.maceco.com

The Kish Company is a leading supplier of industrial minerals, extenders, additives and lightweight spheres to the plastics, paint, rubber, ink, adhesive and sealant industries. The Kish Company is able to offer extensive technical experience to successfully integrate our products into your systems. With our international network of resources, we offer the highest quality minerals in the world and our 14 distribution points throughout the world will meet your same day inventory needs. Contact us at (800) 886-5238 or [email protected] www.kishcompany.com

Soyanol ™ High Performance, Sustainable Additive Solutions Multiple functions including coalescent, plasticizer, and dispersant Zero and Low-VOC Solutions for solvent and water-born formulations Compatible with most resin systems Excellent Freeze / Thaw performance

Soyanol™ is the perfect blend of high performance, versatility, and sustainability.

Family Of Companies Repco, Inc – Tokyo Japan Sphere One, Inc – Chattanooga Tennessee, www. sphereone.net

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Liquid

Glass Coating Technology

I

recently became aware of this new technology, and the project manager at Nanopool graciously extended to me the liberty of taking previously published material and presenting it in PCI. The following information is taken from the Nanopool website, press releases and an editorial written for journals in the healthcare industry. Nanopool GmbH is recognized as a world leader in SiO2-Liquid Glass Nano Layering technology. Its awardwinning “liquid” glass coatings allow the end user to apply a nano-scale layer of super-durable, super-phobic, highly flexible glass to almost any surface. This technology is revolutionizing how we manage our environment. The liquid glass attributes have resulted in the coating

being regarded as one of the most important surface coating technologies to have emerged in recent years. Apart from a select group of professionals, few people know about this stunning technology. If one walks around the Ataturk’s Mausoleum in Ankara you are walking on it. If you visit certain hospitals in the United Kingdom you are touching it. If you see an unusually clean train you are probably looking at it, and if you wonder how your white settee looks so clean, you may be sitting on it. All of these surfaces have been coated with invisible glass.

SiO2 NLT The SiO2 nano layering technology (NLT) evolved from manipulation of the sol-gel process. This process is a wet chemical technique (chemical solution deposition). While the process has been known for years, Nanopool refined it to create “liquid glass” or “glass in a bottle”. Molecules of SiO2 (pure quartz glass) are isolated and held in a solvent of either water or ethanol. This “solution” can then be wiped or sprayed onto most any surface. The subsequent coating forms a layer of pure glass, which is approximately 100 nanometers thick. The water-based solution is designed for absorbent surfaces such as stone, wood and fabrics, whereas the alcohol-based solution is designed for metal, glass, plastic and painted surfaces. Almost all surfaces can be coated with SiO2 NLT, with the exception of Teflon or other non-stick coatings. Additionally, all surfaces must be completely clean prior to application, as a finger print can be 100 times thicker than the coating. There are no polymeric binding agents used in the solution – only SiO2 and water or ethanol. It is believed that Van der Waals forces enable the SiO2 layer to polymerize rapidly and adhere to the surface. Keep in mind that nano-scale technologies perform very differently than their micro- or macro-scale counterparts – hence the unusual characteristics and benefits.

By Darlene Brezinski, Ph.D., Editor | PCI Magazine 24

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024 Liquid Glass FT.indd 24


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Liquid Glass Coating Technology

Key Point Summary of SiO2 NLT 䡲 SiO2 (silicon dioxide) is the chemical term for quartz glass. 䡲 Liquid glass is invisible to the naked eye, as it is only 100 nm thick – (approximately 500 times thinner than a human hair). The coating does not alter the appearance or texture of the treated surface. 䡲 SiO2 “liquid glass” can be applied to all surfaces, (including glass, metals, fabrics, stone, plastic, food packaging, operating theatres, skin, computers, food processing areas, cars, shipping, aircraft); in fact the list is almost endless. 䡲 Liquid glass is applied by spraying, dipping or wiping. 䡲 It is food safe and mucosa friendly, and has no negative physiological impact. 䡲 It is super-phobic (rejects all soiling elements, including solvents, acids and alkalis (0.5 pH to 12.5 pH) 䡲 It is highly durable; domestic quality variants last approximately one year per application. Professional variants last 10 years. Certain treatments last even longer. (The coating will not decay and is only removed by chemical or mechanical action.) 䡲 It is heat tolerant (-150 to +450 °C) and so can be applied to ovens, freezers, wash basins etc. It removes the need for ovencleaning chemicals; simply clean ovens with water and a cloth. It is UV-stable, chemically inert and cell neutral and so it can be used for in-vivo application. 䡲 It is “particle free” i.e., does not contain any potentially dangerous nano particles. 䡲 It is flexible (200%) and breathable at the molecular level and so it can be applied to wood, fabrics, stone work and statues, as these areas need to breathe and expand /contract. 䡲 It can be applied with great ease, no special equipment is needed. 䡲 All surfaces become easy to clean, and in most instances cleaning can be carried out with water alone. This is the case within butchery departments, where NP-coated areas are cleaner after being washed with water than those areas which have been cleaned with a chlorinated agent. Savings of 30% on cleaning are the norm. (Audited figures.) 䡲 Treated surfaces become "bio-static " through ionic exchange (this creates an environment that will not support bacterial growth) and so the treatments are ideal for sinks, taps, food-prep areas, nurseries, door handles, toilets, cash registers, conveyor belts, gyms, schools, hospitals, chiller cabinets etc. Nanopool supplies an anti-bacterial variant, which satisfies ASTMS E 2180.The antibacterial variant kills bacteria for the life of the coating. Most antibacteria treatments are short lived or exceptionally expensive. The company offers savings of over 3000% on items such as antibacterial light switches and shower trays. 䡲 This technology is new to the UK, but the company already works with some of the world’s largest organizations. They also treat trains (London-Midland), both inside and out, Kempinski hotels, Spar food processing factories, McDonald’s (Austria and Germany), bakeries, health care environments etc. These products are now being applied in some of Europe’s leading supermarkets. The company has recently coated Ataturk’s Mausoleum in Ankara (750,000m2). 䡲 A range of specialist products is provided, such as anti-corrosion, anti-graffiti, anti-fingerprint, skin protection, cork protection and variants for plants. 26

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024 Liquid Glass FT.indd 26

The glass coating, being approximately 100 nanometers thick, is completely undetectable, is food safe and environmentally friendly and also a winner of the U.K. Green Apple Award.

Application Markets The automotive market is embracing the technology for coating fabrics, windscreens, painted surfaces and alloy wheels. Marine coatings, including anti-fouling, will soon be available. Applications in healthcare and food production environments are already advanced. There is no doubt that there is tremendous benefit to the clean room industry. For fabrics, liquid glass surrounds each individual filament within the fiber with the invisible coating. This protective layer of flexible pure glass ensures that soiling agents are unable to effectively adhere to the surface. Liquids such as coffee, red wine, etc., simply roll off treated textiles. Many companies all over Austria have discovered the advantages of nanotechnology and rely on the experience and the unique sol-gel technology of Nanopool. “In our recently reopened restaurant in Wals near Salzburg, Nanopool has refined all surfaces by means of coating,” says Josef Klingler, Manager of McDonalds Salzburg. “This coating is effective, durable and anti-microbial. This means no more adhesion of soil, long-lasting protection against adhesion of mould bacteria, and considerably reduced use of chemicals for cleaning.” By the way, no follow-up treatment will be necessary after accurate cleaning. The coatings are now recognized as being suitable for agricultural and in-vivo application. Vines coated with SiO2 do not suffer from mildew, and coated seeds grow more rapidly without the need for anti-fungal chemicals. This will result in farmers enjoying massive yields. For in-vivo application items such as stents can be coated, which will create anti-sticking features. Catheters and sutures will also cease to be problematic in the future. In essence, this is one of the most significant new technologies to have emerged over recent years. This is a rather bold claim but it is made with justification as Nanopool provides a technology that allows the user to create longterm, easy-to-clean, bacteria-free surfaces using an ultra environmentally friendly and low-cost technology. 䡲 For more information, visit www.nanopool.eu or www.nanopool.co.uk or e-mail [email protected].


5/19/10 12:18:24 PM

Highly Flexible a Nanocomposite C on Compliant Surfaces

O

ptically transparent solids have numerous applications and have experienced widespread use for centuries. Glass was the predominant material over most of that time, with additives often included to engineer specific properties. A wide range of refractive indices and absorption characteristics were eventually produced. Glass and common metal oxides eventually spanned the refractive index range from 1.44 (SiO2) to 2.7 (TiO2). In the modern era, polymers have become a common alternative to glass in many applications. Visibly transparent polymers have the advantages of low cost, processing ease and a wide range of physical properties. Additionally, polymers exhibit strain behavior that far exceeds the limits of glass. Urethanes and polycarbonate, in particular, also have very high impact resistance. However, transparent polymers have a more limited range of refractive index than glasses and generally scratch more easily. An inorganic-organic nanocomposite ideally maintains the flexibility, low cost and processability common with organic polymers, while extending other material properties beyond the limits of the host polymer. With proper selection, loading and

FIGURE 1 | Schematic of four different functional schemes using organosilanes. (D)

(C)

O C

O

C C

C

C

C

C Si

Si O

O NP

O Si

(A)

F

C

O

(B)

Si

C

N

surface modification, inorganic nanoparticles can be used to significantly broaden the engineering potential of transparent polymers. Over the past few decades, excitement has built around these hybrid inorganic-organic materials that can offer improved mechanical, optical, thermal and electrical properties. Transparent nanocomposite films on the order of nanometers to microns have successfully been used to improve abrasion resistance, alter reflectance and minimize the UV exposure of substrates. The advantages of these materials include low processing costs, low processing temperatures and extended strain ranges over ceramic films. The primary optical property of a material is its complex index of refraction, which is an engineering constant that explains the propagation and absorption of electromagnetic waves through materials and at interfaces. The design and production of optical filters is mainly accomplished through the combination of thin films with unique refractive indices.1 These are typically dielectric and metal films that are almost exclusively deposited using vacuum deposition. Although these materials have been studied extensively, they have significant disadvantages related to the required processing steps and limited mechanical properties of the resultant films. Nanocomposites composed of inorganic nanoparticles embedded in an organic polymer matrix directly address these issues.2 The primary challenge for nanocomposites is to alter the optical properties of a material without affecting the visible transparence of the final article. When an electromagnetic wave encounters a boundary between two materials of discrete refractive index, the direction of the wave is altered both through reflection and refraction. This holds true with sub-micron particles, where the optical dimension (refractive index and diameter) must be engineered so as to not scatter light waves (scattering decreases transparence). Thus, a homogenous distribution of discrete, mono-disperse nanoparticles with dimensions less than 1/10 the wavelength of the encountered light must occur within these nanocomposites to ensure high visible transparence. The focus of our research for the past several years has been spin coating inorganic-organic nanocomposite films that are used on visibly transparent, flexible substrates. The engineering limits of polymers have been extended

By Thad Druffel, Matthew Lattis, Omar Buazza and Galen Powers | Optical Dynamics, Louisville, KY 28

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028 Optical Dynamics FT.indd 28

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e and Transparent e Coatings through incorporation of nanoparticles that make up over half the volume of the composite. Spin coating is practically limited to substrates that cover less than a square meter. It will be required to coat larger areas to move this technology towards broader applications. Large-area deposition of nanocomposites could more effectively and economically reduce unwanted reflections from consumer products such as cell phones, computers and e-book readers. Inexpensive deposition of thin-film filters over large areas is also applicable to solar energy, where management of the solar spectrum is beneficial (UV and IR reflectors, improved visible transmittance and spectrum splitting). Additionally, these large-area processes can be adapted to three-dimensional deposition, further extending the reach of this technology.

Nanoparticles In optical applications, it is crucial to obtain ultrafine and stable nanodispersions in order to produce thin films with low surface roughness and haze. Although the primary size of most commercial nanoparticles is quite small (5-50 nm), the high nanoparticle surface energies cause agglomeration in the synthesis and post-synthesis processes. This leads to dispersions with primary particles in the nanometer range, but with a significant number of large particle groups exhibiting complex shapes and morphologies due to agglomerated and aggregated networks. These conditions negatively impact haze and transparency.3 The term agglomerates relates to groups with weak interparticle bonds that allow them to be re-dispersed in a solvent. Ball milling and ultrasonication are typically used to break up agglomerates. The term aggregates (or hard agglomerates) describes groups with primary particles held together by strong attractive forces.4 Aggregates formed during high-temperature synthesis often persist after ultrasonication or milling and must often be removed through centrifugation or filtration. Solution-based synthesis of nanoparticles was first reported by Stober in 19685 using a tetraethoxy silane (TEOS). Many researchers have improved on the original methods, with a key enhancement being modification of particle surfaces with functional organic groups, designated as an ORMOSIL (Organically Modified Silica).6 This method served as a basis for production of other metal oxide nanoparticles through hydrothermal and solvothermal methods. The solvothermal method is carried out in a closed reactor in which precursors of the metal oxide are

mixed into a solvent. The reactants are heated and reaction kinetics are adjusted to alter the size of the nanoparticles. Solution synthesis of nanoparticles has three very important advantages: • The nanoparticles are grown and harvested in a liquid, reducing airborne contaminants. • High heats are not required, so the presence of aggregates is reduced. • The solvents are amenable to several surface functionalization schemes. Preservation of discrete nanoparticles is of utmost importance for high visible transparence in the finished article. Dispersion of nanoparticles in liquids and solids can be aided by functionalization of the particle surface. Several functionalization schemes have been demonstrated in literature, including the use of ions7, surfactants, ligands8, polymers9, coupling agents10, and shells of silica11 or polymer.12 The nanoparticles discussed here are metal oxides, which are subject to simple functionalization using organosilanes (as typically used with ORMOSILS). The nanoparticles can be functionalized with different groups that can include single groups that may or may not be polymerizable (Figure 1). Functionalization that includes a polymerizable group will aid in making the nanoparticles an integral part of the matrix.

Engineered Nanocomposite Films The third element of these nanocomposites is the polymer that envelops the particles in a matrix, which may also include covalent bonds between the inorganic and organic phases. Nanoparticles can be dispersed directly into a swelled polymer, although dispersing monomers or oligomers directly into a nanoparticle solution has advantages. Many monomers are soluble in the same solvents the nanoparticles are already stabilized in and can polymerize to functional groups on the particles. Once the solvent has been removed, polymerization of the nanocomposite can be performed using thermal or photoinitiated curing. The optical and mechanical properties of a nanocomposite are engineered by varying monomers, initiators, curing conditions and the concentration of nanoparticles used in the matrix. With spin coating techniques, up to 65 volume percent nanoparticle loading is possible, which is near the theoretical limit of close packing with spheres. Between the properties of the base polymer and the fully PA I N T & C O A T I N G S I N D U S T R Y


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Highly Flexible and Transparent Nanocomposite Coatings on Compliant Surfaces

FIGURE 2 | Effect of nanoparticle agglomeration on light waves. (A) Schematic showing an agglomeration of primary particles that do not allow the light wave to pass through. The large, rough surface encountered by the light waves will result in reflected beams that travel in many directions. (B) Shows how steric stabilization techniques maintain discrete separations between the nanoparticles allowing light to pass unobstructed.

(A)

(B)

loaded nanocomposite, a continuous realm of possible combinations exists. Spin coating is a well-understood deposition technique that produces reproducible, uniform films that are spread across a substrate with considerable shear forces. When the optical diameter of the nanoparticles becomes too large, scattering results as light waves are reflected from the boundary of the inorganic and organic phases (Figure 2). A homogeneous dispersion of discrete mono-disperse nanoparticles will yield a highly transparent nanocomposite. Models predicting light scatter intensity in a nanocomposite show a linear relationship with path length, packing density and refractive index ratio, but scattering varies with the cube of particle diameter.13

−3Vp lφ 3 I = exp ( m−1) I0 4λ 4 FIGURE 3 | Refractive index dispersion of nanocomposites featuring varying volume fractions of ZnO dispersed in a UV-cured polyurethane acrylate. 1.80

Refractive Index

50% 1.70 40%

where I/I0 is the ratio of transmitted intensity to the initial intensity, Vp is the volume packing density of the nanoparticles, l is the path length, φ is the diameter of the nanoparticle, λ is the wavelength of light, and m is the ratio of the refractive indices at the inorganic to organic boundary. The refractive index of a nanocomposite is the combination of the volume fraction of the inorganic and organic components. The composite refractive index can be modeled as:

30% 1.60

n 2 = ∑ i vi ni 2

25%

1.50

5%

400

500

600

(1)

700

Wavelength (nm)

800

(2)

where ni and vi are the refractive index and volume fractions of the components.14 The inorganic nanoparticles have a non-uniform refractive index across the visible spectrum, whereas the organic polymer is nearly constant. To demonstrate this effect, measurements were made using nanocomposite films approximately 500 nm thick with refractive indices between 1.5 and 1.75 (measured at

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FIGURE 4 | UV absorption of ZnO nanocomposites as the volume density of nanoparticles is increased. A linear relationship between absorption and nanoparticle volume is observed.

Absorbance (A.U.)

2

0 0

20

40

60

Volume Density of ZnO (%)

FIGURE 5 | Spin coating equipment to deposit thin films. (A) Schematic of coater showing the staging, coating and curing stations of the machine. (B) Cross-section of the coating bowl showing movement of air through the bowl and application of chemistry from below the substrate.

Coating Chemistry Reservoirs

Air In

Chuck Substrate

HEPA Filter cure

coat

Substrates

clean

Air Out Coating Dispense Filter Nozzle Chemistry In

480 nm). The range of refractive indices was achieved with 5-50% loading of ZnO nanoparticles in the UV-curable monomer TMPTA. Results are shown in Figure 3. The films were applied to a substrate using an Optical Dynamics spin coater. The source of the ZnO is a nanoparticle dispersion in methyl ethyl ketone (MEK) produced by Umicore (Zano MEK 067). It is reported as containing 30 nm ZnO nanoparticles at 45 weight percent and uses a surfactant to maintain nanoparticle separation. Reflectance was measured with a contact spectrophotometer (F20 by Filmetrics), with thickness and roughness determined using a contact profilometer (XP-1 by Ambios corporation). This data was then used to determine refractive index using a Cauchy model. It should be noted that the refrac-

Coating Bowl

tive index of the fully loaded ZnO film has been determined to be approximately 1.75, which is slightly lower than the expected 1.82. This is most likely due to the added surfactant reducing the effective refractive index of the ZnO nanoparticles. A similar study of TiO2 nanocomposite films was undertaken and resulted in a maximum refractive index of 1.88 with volume packing of 65 percent. In this case surface modification was responsible for the reduced refractive index. These films were used to produce thin-film reflective filters with up to 38 layers, with the resultant stack surviving strains up to 25 percent.15 There is potential for the use of nanocomposite films in absorptive filters that maintain high visible transparence. A possible use is protecting eyes from harm-

Visit ads.pcimag.com PA I N T & C O A T I N G S I N D U S T R Y


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ful ultraviolet or infrared Deposition The films discussed above wavelengths. Metal oxides FIGURE 6 | Bulk nanocomposites utilizing functionalized and un-functionalized nanoparticles. were spin coated with equiphave high absorption in the Functionalized Un-functionalized ment that was specifically UV region with low absorpdesigned to deposit thin-film tion in the visible range, nanocomposites. The coater which makes them ideal for moves up to four 80-mmoptical applications requirdiameter substrates through ing UV blocking. It is well three process steps: cleanknown that titanium dioxing, coating and curing ide and ZnO have very high (Figure 5a). The unit mainabsorption in the ultraviotains a consistent internal let region. The visible and temperature of up to 100 oF UV response of 500-nmfor evaporation consistency thick films containing and includes a HEPA filter to varying volume ratios of reduce film defects. The sysZnO nanoparticles was 500 nm 100 nm 100 nm tem is completely programmeasured using a UV-Vis mable and can deposit up to spectrophotometer (8453 six distinct coating chemistries. by Hewlett Packard). The ZnO disperA similar study of the impact of voluSurfaces to be coated are first cleaned sions demonstrated sharp changes in metric loading of nanoparticles on the with a high-pressure wash (1000 psi) to response at about 380 nm, as expected modulus of a thin film resulted in a maxiremove fine particulates. The substrate when the UV absorbance of ZnO is conmum modulus near 60 percent loading.16 In this study, silica nanoparticles were is then moved to the coating bowl where sidered. The UV absorbance (λ = 340 used at volumes ranging from 30 to 75 one of six chemistries can be applied to nm) was linearly related to the volume percent and the modulus was measured the spinning substrate. The liquid coatfraction of ZnO in the films (Figure 4), as using nanoindentation. ings are filtered at the nozzle (5-micron predicted by equation 1. filters) and applied to the spinning substrate (~1000 rpm) using computer controlled solenoid valves (Figure 5b). The dispersions are applied from beneath the substrate and readily coat flat, cylindrical, toric or spherical shapes. All of the coating parameters (spin speed, substrate sweep over the dispense nozzle, dispense pressure, dispense time, air flow and air temperature) are computer controlled, and solvent vapors are removed from the coating chamber using a fan. After the coating is applied, the films are cured using a pulsed xenon strobe lamp. The substrate can then go back to the coating bowl for subsequent layers or be returned to the staging area, after which the next substrate can be processed. The system does not require high temperatures or pressures and deposits films ranging from roughly 30-3,000 nm with an accuracy of +/- 5% for each layer. Spin coating involves the thinning of a liquid chemistry that is spread across a spinning substrate as solvent evaporation leaves behind the solute. This well-understood technique controls film thickness Good ideas don’t have office hours, which is why you can primarily through the viscosity of the reach us 24/7 using WACKER E-Solutions. You can order solution and the spin speed used during products, discuss issues with colleagues and experts worldfilm formation. The repeatability of the process is very high as long as the coating wide and develop joint solutions – quickly, reliably and environment is well controlled, since this highly efficiently. And at the other end of the fast connection, leads to solvent evaporation rates that are you always know there will be a real person waiting. nearly constant. Initial film thickness is www.wacker.com/e-business set by a balance between the centrifugal

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028 PCI07094Wack.indd Optical Dynamics FT.indd 1 32

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forces applied to the film as the substrate spins and viscous forces that increase as evaporation takes place. Once these forces balance, evaporation becomes the primary driver of film thinning. The forces encountered during spin coating are significantly larger than gravitational forces, so coating complex geometries with negligible variation in coating thickness is practical. Additionally, these forces allow extremely high nanoparticle packing densities to be achieved. Spin coating is not an ideal candidate for large substrates, and thus the engineer is faced with depositing high-volume-density films without a simply applied body force to overcome the thermodynamic surface forces of the nanoparticles. A large-area deposition will still need to overcome the tendency of nanoparticles to agglomerate. The functionalization of the nanoparticle surface should reduce the surface energy and may aid in the self assembly of the nanocomposite. The stabilization techniques used to keep nanoparticles dispersed in a solvent may not translate into a discrete dispersion in the nanocomposite. Systems that rely on ions to maintain nanoparticle separation in an aqueous dispersion will begin to agglomerate as the water is removed. Steric stabilization techniques using surfactants can also create films that are poorly suited for multilayer applications, since these methods can interfere with interlayer adhesion. Ideally, functionalization would reduce the surface energy of the nanoparticles to a level

FIGURE 7 | Dip-coated thin films of CeO2 (right) and alternating CeO2/SiO2 layers (left).

A

B

comparable to that of the monomers used in the system, thus creating a bulk nanocomposite monomer. A demonstration of a bulk nanocomposite using organosilane functionalization techniques reducing the surface energy of the nanoparticles to achieve a homogeneous dispersion is shown in Figure 6. Two mixtures were created that use alcohol-dispersed silica nanoparticles (Nissan Chemistries IPA-ST) at 10 volume percent in TMPTA. In the first mixture the silica dispersion was used as supplied. The second mixture was functionalized using a methacryloxypropyl trimethoxysilane. The mixtures were then placed into a rotary evaporator and the alcohol was removed and the bulk monomer nanocomposite was cured using UV radiation. The nanoparticles that were not functionalized tended to agglomerate in the polymer matrix, which created haze. The nanoparticles that were functionalized remained separated in the dispersion as shown. An ideal application method for coatings involving large areas is dip coating. A simple setup was built to pull a glass slide out of a nanoparticle-based coating solution at speeds between 1 and 25 mm/s. The nanocomposite dispersion was cerium dioxide, which is available as a colloidal suspension from Sigma-Aldrich (Product No 289744), and a trimethylolpropane triacrylate. The ceria dispersion was functionalized such that acrylate groups surrounded the nanoparticles. The total volume of nanoparticles in the resultant film was 40 percent. The thickness of the coating was determined to be 270 nm, with a refractive index of 1.8 (measured at 480 nm). The original formulation was then diluted to produce a film on the order of a quarter wavelength (approximately 70 nm), which is shown in Figure 7b. This quarter wave producing high-index chemistry was used along with an SiO2-bearing nanocomposite to produce a 9-layer reflective stack based on an alternating low/high pattern (with curing between dip coating steps). The resultant film is shown in Figure 7a. Another technique suitable for roll-to-roll coating is spray deposition using the setup shown schematically in Figure 8. A trial was run depositing a nanocomposite with approximately 40 percent nanoparticles by volume. A spray nozzle and micro dispense valve from Lee ElectroFluidic Systems were used to spray the chemistry. The valve was driven at a frequency of 20 Hz, and a substrate was slowly passed under the nozzle to produce a continuous film across. The resulting coating was highly transparent at a thickness of 2.5 microns. The refractive index of the coating was determined to be approximately 1.75.

Conclusion FIGURE 8 | Schematic of roll-to-roll coating of nanocomposites using spray. Deposition

Air Knife

UV Cure

Adhesion layer Pick-Up Roll

Uncoated Roll

34

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In this paper we reviewed the engineering of nanocomposite thin films by adjusting inorganic nanoparticle loadings in a polymer matrix. The nanocomposite films were engineered for refractive index, absorbance and modulus. The preliminary work focused on spin coating techniques in which optical and mechanical properties were engineered with nanoparticles composing nearly 65 percent of the volume. In order to move the technology to large-area deposition and increase applicability to additional industries, nanoparticle surface modification is essential to



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equalize the surface energies of the nanoparticles and surrounding monomers. Thus, large body forces are not required to overcome the tendency of the nanoparticles to agglomerate. Three systems were shown demonstrating that highly packed nanocomposites can be formed using scalable deposition techniques. 䡲

Acknowledgements

References

This work was supported in part by the National Science Foundation SBIR Phase II award No. 0848825 and in part by an award by the Kentucky Cabinet for Economic Development, Department of Commercialization and Innovation, under the grant agreement KSTC-184-512-09-069 with the Kentucky Science and Technology Corporation.

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Heavens, O. S. Optical Properties of Thin Solid Films; Butterworths, London, 1955. 2 Druffel, T.; Geng, K.; Grulke, E. Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter. Nanotechnology 2006, 17(14): 3584. 3 Mandzy, N.; Grulke, E.; Druffel, T. Breakage of TiO2 agglomerates in electrostatically stabalized aqueous dispersions. Powder Technology 2005, 160: 121- 126. 4 Park, B.; Smith, D.; Thoma, S. Determination of agglomerate strength distributions: Part 4 Analysis of multimodal particle size distributions. Powder Technology 1993, 76: 125-133. 5 Stober, W.; Fink, A.; Bohn, E. Controlled growth of monodisperse silica spheres in the micron size range. J. Colloid Interface Sci. 1967, 26: 62-69. 6 Chisholm, B.; Resue J. UV-Curable, Hybrid Organic-Inorganic Coatings. International Waterborne, High-Solids, and Powder Coatings Symposium. New Orleans, 2003, Paint and Coatings Industry 2003, 6. 7 Khrenov, V.;Klapper, M.; Koch, M.; Mullen, K. Surface functionalized ZnO particles designed for the use in transparent nanocomposites. Macromol. Chem. Phys. 2005, 206: 95-101. 8 Grubbs, R. B. Roles of polymer ligands in nanoparticle stabilization. Polymer Reviews 2007, 47: 197-215. 9 Kislenko, V. N.; Verlinskaya, R. M. Adsorption of polyacrylic acid and its copolymers with acrylonitrile on zinc oxide particles. J. Colloid Interface Sci. 2002, 250: 478-483. 10 Allen, C. G.; Baker, D.J.; Albin, J.M.; Oertli, H.E.; Gillaspie, D.T.; Olson, D.C.; Furtak, T.E.; Collins, R.T. Surface modification of ZnO using triethoxysilane-based molecules. Langmuir 2008, 24: 13393-13398. 11 Tago, T.; Tashiro, S.; Hashimoto, Y.; Wakabayashi, K.; Kishada, M. Synthesis and Optical Properties of SiO2-coated CeO2 Nanoparticle. J. Nanoparticle Res. 2003, 1-6. 12 Vedula, R. R.; Spencer, H.G. Adsorption of poly(acrylic acid) on titania (anatase) and zirconia colloids. Colloids Surfaces 1991, 58: 99-110. 13 Novak, B. M. Hybrid nanocomposite materials - between inorganic glasses and organic polymers. Advanced Materials 1993, 5(6): 422-433. 14 Seferis, J. C. Refractive Indeices of Polymers. Polymer Handbook. J. Brandrup, E. H. Immergut and E. A. Grulke. Hoboken, John Wiley and Sons. 1999, 2: 571-582. 15 Druffel, T.; Lattis, M.; Spencer, M.; Buazza, O. Elastic behaviour of a nanocomposite thin film undergoing significant strains. Nanotechnology 2010, accepted 16 Druffel, T.; Mandzy, N.; Sunkara, M.; Grulke, E. Polymer nanocomposite thin film mirror for the infrared region. Small 2008, 4(4): 459-461.

For more information, visit www.opticaldynamics. com. This paper was presented at the American Coatings Conference, Charlotte, NC, April, 2010.


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Advancements in One-Component M

Urethane Primer

A

n important class of specialty isocyanates includes one-component systems that cure with moisture. One-component PU systems are prone to surface foaming and require special surface preparations. Since it is more convenient to apply a single one-component primer system compared to a two-component system, Huntsman has developed a new moisture-cure MDI, SUPRASEC® 9611, which has low viscosity, low foaming characteristics and is VOC free. This paper addresses physical properties, reactivities and primer processing conditions of this new moisture-cure MDI and compares the properties to existing primer systems.

Introduction Two-component spray coatings based on polyurea, hybrid and polyurethane elastomer technology continue to find commercial success in protective applications for civil infrastructure, process plants and many more applications.1,2 It is critical to the success of these coatings to follow proper procedure in preparing the surface of the substrate.3 For concrete surfaces this may include chemical etching or sand blasting. However, surface preparation may not always guarantee proper adhesion or a coating without defects. There are potentials for an improperly prepared surface, an undesirable surface tension, or perhaps a damp substrate, which can cause an excessive outgas. All of these issues could lead to blisters or pinholes in the coating surface or could even potentially cause delamination of the coating from the substrate. Correcting these problems after the fact is both expensive and timely. When encountering difficult substrates or surfaces, the spray applicator can reduce the likelihood of serious problems with

TABLE 1 | Product descriptions of primers. Product

Description

SUPRASEC 9611

Moisture-cure MDI; no VOC 2-component urethane 1:1 by SUPRASEC 9584 and castor oil volume RUBINATE 9511 and xylenes Moisture-cure MDI; 10% VOC Acrylic emulsion #1 Water-based acrylic with filler Acrylic emulsion #2 Water-based acrylic; no filler Emulsifiable MDI and water SUPRASEC 9259 and water 75:25 by weight

the application of an appropriate primer. Primer systems can increase the adhesion of the overall coating system. This occurs when a primer is able to penetrate into a porous surface and create a mechanical bond. The application of the primer in this case increases the overall strength of the substrate. In addition, the topcoat has the opportunity to form a chemical bond with the primer. These covalent bonds also increase the strength of the overall adhesion. Finally, the primer acts as a barrier and will prevent the contamination of moisture into the surface of a substrate and therefore inhibit some of the surface defects that may have been encountered otherwise. A number of two-component polyurethane systems have been evaluated as primers over the years and recently were discussed by Camargo and Skok.4 They described the performance benefits of using a two-component coating as a robust primer over damp concrete prior to a top coat. The main advantages to the formulator include the ability to adjust coating properties via polyol selection and mixing ratio, and the ability to adjust cure speed through catalyst selections. Despite the benefits mentioned above, in the field it is much more convenient to use a one-component system. Using a one-component system eliminates problems with incorrect mix ratios, improper or poorly mixed components, or limited pot life after mixing. A one-component moisture-cured polyurethane is typically made by reacting excess isocyanate with a high-molecular-weight polyester or polyether polyol. The amount of free NCO groups remaining in these “prepolymers” is generally 16% or lower. Once the moisture-cure prepolymer is applied to the substrate in a thin film, the amount of relative humidity controls the curing speed. The NCO groups in the prepolymer react with the active hydrogen of the water molecule and form an amine and carbon dioxide. Additional NCO groups begin to react with the amine and form ureas until all NCO

By Roeland J. Tuinman, Katie L. Skok and Kevin A. Buck | Huntsman Polyurethanes, Auburn Hills, MI 38

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Moisture-Cured

Technology groups have been consumed. The generated carbon dioxide dissipates from the film and evaporates into the air. If the film thickness is too large or if the amount of moisture is too high, there is an opportunity for the CO2 to become trapped in the film and to cause an undesirable effect of foaming and blisters. This effect can become exaggerated if the viscosity of the prepolymer is too high. The high viscosity of the prepolymer causes the CO2 gas to diffuse more slowly from the film and increases the likelihood of trapped gas. For this reason, it has been a common practice in the industry to add solvents to the prepolymers in order to reduce viscosity. In addition to reducing foaming effects, the overall lower viscosity helps improve the penetration into porous substrates and, therefore, increases the bond strength. Unfortunately, the addition of solvent into a coating system greatly increases the overall VOC content. The industry has shown a trend away from this practice when at all possible. For this reason, Huntsman has developed SUPRASEC 9611, a non-VOC, low-viscosity, MDI moisture-cure prepolymer, designed for use as a primer on porous substrates.

Experimental Materials Six primer coating chemistries were evaluated in this study. The primers, most of which are commercially available, include a waterborne acrylic with fillers; a waterborne acrylic without fillers; a two-component isocyanate/castor oil system; a one-component, solvent-based isocyanate; a non-VOC, one-component-based isocyanate; and an emulsifiable-based isocyanate/water system. The products and descriptions for the six comparative primers are listed in Table 1.

Characterization Curing comparisons between systems were conducted at 23 °C and 50% humidity using a thin-film B-K drying recorder from Gardco. Films of 20-mil thickness of each system were applied onto clean glass plates and allowed to cure for 1 week. The films were removed from the glass and tested for tensile strength, elongation and Die C tear according to standard ASTM methods, ASTM D 882 and ASTM D 624 respectively. Adhesion specimens were prepared on either wet or dry concrete blocks by coating the substrate with the primer at a 5-mil thickness using a brush. Dry blocks were conditioned for 1 week at 23 °C and 50% humidity. Wet blocks were submerged in water for 3 hours. Once removed from the water, the blocks were primed immediately, while still saturated. A standard polyurea formulation based on a commercial MDI prepolymer was sprayed at different time intervals following the primer application using a Gusmer H20/35 proportioning unit and a Graco Fusion Air Purge Gun, model AR2020. The details of the polyurea

system can be found in Table 2. After one week, adhesion specimens were prepared with 1-inch diameter test dollies and pulled off with an Elcometer 106 Adhesion Tester to measure strength and failure mode.

Results and Discussion Physical Properties Drawdowns of films (20 mil) on glass provided bubble-free and defect-free coatings from which we were able to evaluate physical properties of each primer chemistry, with the exception of the emulsifiable system, SUPRASEC 9259 and water mixed at a 75 to 25 weight ratio. This system formed a brittle film that could not be tested. Physical properties of the remaining systems are listed in Table 3. Urethane chemistries displayed the highest overall physical strength. The one-component system of RUBINATE 9511 and xylenes had the highest tensile values, followed by SUPRASEC 9611. This was expected since the RUBINATE 9511 and xylenes combination had the highest percentage of free NCO groups available to react with water and form urea hard segments, which provide strength to the coating. The acrylic emulsions were softer materials with lower tensile strength. The non-filled system, Acrylic Emulsion #2, provided an advantage in physical properties such as tensile and tear strength when compared to the filled system.

Reactivity The reactivity profile of each primer chemistry is presented in Figure 1. The open time refers to the amount of time in which the primer remains a liquid. The viscosity of the liquid increases until the material has gelled into a

TABLE 2 | Description of spray polyurea system. Isocyanate Component Resin Component

Reaction Profile

Physical Properties

SUPRASEC 9608 Jeffamine D-2000 Jeffamine D-5000 DETDA Rebus 6021 Gel time Tack free time Tensile strength Tear strength Elongation Shore D Taber abrasion

100 parts 64.31 3.57 28.54 3.57 4 sec 6 sec 3200 psi 600 pli 330% 50 0.007 g/cycle

TABLE 3 | Physical properties of primers. Primers S 9611 S 9584 and CO R 9511 and xylenes Acrylic emulsion #1 Acrylic emulsion #2

Tensile, psi

Elongation, %

Die C Tear, pli

3383 2450 5115 529 1300

85 43 101 264 83

440 260 523 155 242

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Advancements in One-Component Moisture-Cured Urethane Primer Technology

FIGURE 1 | Reactivity profiles of primers. Primer Reactivities 75 ºC, 50% Relative Humidity S 9611 S 9584 and CO R9511 and Xylenes Acrylic Emulsion #1 Acrylic Emulsion #2 S 9259 & Water 0

2

4

6

Open time

8 10 12 14 Hours Gel time Tack free time

16

FIGURE 2 | Adhesion to dry concrete. 700

Adhesion

Adhesive Strength, PSI

600 500 400 300 200 100 0

S 9611

S 9584 and CO 1 h Cure

Acrylic Emulsion #1 3 h Cure

Acrylic R9511 and S 9259 Emulsion Xylenes and Water #2 6 h Cure 24 h Cure

Unprimed Adhesion = 400 psi

FIGURE 3 | Adhesion to wet concrete. 450

Adhesive Strength, PSI

400 350 300 250 200

The six primers were brush applied at 5-mil thickness to both dry and wet concrete. A polyurea topcoat was sprayed over the primers at 1, 3, 6 and 24 hours after the primers were applied. The adhesion values of the complete primer and polyurea system to dry and wet concrete were measured (Figure 2). For the dry concrete, increased adhesion was noted with the SUPRASEC 9611, the RUBINATE 9511 and xylenes, and the SUPRASEC 9584 and castor oil system. Both acrylic systems had average values below 300 psi, which was a slight decrease from the non-primed adhesion value. The polyurea system without primer had an average of 400 psi adhesion to concrete. The wet concrete contributed to lower adhesion values overall, when compared to the dry concrete data (Figure 3). The concrete was extremely saturated with water before priming, and the conditions tested represent the absolute worse case scenario for a moisture-contaminated substrate in the field. The adhesion value of polyurea to concrete without any primer was on average 100 psi. There was an overall improvement in adhesion when a primer was used prior to the polyurea topcoat. The greatest adhesion was obtained when using SUPRASEC 9611 or SUPRASEC 9259 and water system. For both one-component systems, there was a trend towards improved adhesion after 24 hours. Data beyond 24 hours was not evaluated in this study, although it has been shown previously to yield good adhesion.5 It is our belief that beyond 24 hours, the opportunity for contamination over the cured primer in a commercial or an industrial setting is potentially large.

Visual Inspection

150 100 50 0 S 9611

S 9584 and CO 1 h Cure

Acrylic Acrylic R9511 and S 9259 Emulsion Emulsion Xylenes and Water #1 #2 3 h Cure 6 h Cure 24 h Cure

Unprimed Adhesion = 100 psi 40

solid, as indicated in Figure 1 as “gel time.” The material loses its stickiness or tackiness, as indicated by “tack free time”, which also indicates that the material has reached full cure. At 50% relative humidity, both acrylic emulsions demonstrated the quickest cure. Final cure was reached within 2 hours time. The one-component moisture-cure isocyanates, SUPRASEC 9611 and RUBINATE 9511 with xylenes, reached final cure within 3 hours. While these cure profiles demonstrate the typical curing behaviors, increased humidity and temperatures will decrease the amount of time needed to reach final cure. Previous work has demonstrated the ability to spray a polyurea topcoat over the primer before it has reached its final cure.3 Increased adhesion values are noted in the urethanebased systems even when the polyurea is applied over wet or tacky primers. In these instances it is presumed that the unreacted NCO groups remaining in the primer have the opportunity to be covalently bonded into the polyurea matrix and thus the adhesion is increased.

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The visual inspection of test dollies after the adhesion testing is complete can provide extremely important information regarding the adhesion performance of the primer and topcoat. The adhesion tester and a dolly that has been “pulled off” from the concrete block are displayed in the photo in Figure 4. In addition, photos were taken of the dollies after they were removed from both dry and wet concrete that had been primed 1 and 24 hours before the application of a polyurea topcoat (Figures 5, 6). The dark


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Advancements in One-Component Moisture-Cured Urethane Primer Technology

FIGURE 4 | Elcometer adhesion testing on concrete brick with primer and polyurea topcoat.

FIGURE 5 | Adhesion dollies displaying failure mode for concrete coated 1 h after primer coat.

FIGURE 6 | Adhesion dollies displaying failure mode for concrete coated 24 h after primer coat.

than the wet specimens on the right. Comparison of both pictures reveals that the 24-hour specimens appear to have a higher concentration of concrete failure than the 1-hour specimens. High levels of concrete failure were also observed on the dollies of the urethane systems coated with polyurea after 3 and 6 hours. This indicates that a large window for topcoat application exists.

Conclusions The use of a primer under a polyurethane, polyurea or hybrid coating is a critical step that can enhance the performance of the coating system, especially when encountering a difficult substrate. Not only can the primer improve adhesion to the substrate, it can also eliminate the possibility of moisture contamination during the topcoat application. Since it is more convenient to use a one-component product in the field, Huntsman has developed a one-component moisture-cure MDI, SUPRASEC 9611, which has low viscosity, low foaming characteristics and is VOC free. 䡲

Acknowledgements particles shown on the dollies are actually pieces of the concrete that have been pulled from the concrete block. Concrete failure of this type is highly desired because it indicates that the primer has successfully penetrated into the substrate. The dollies in the photos that appear white have not removed any of the concrete. One can visually see the white color of the polyurea coating, which indicates that the primer was not as effective. In Figure 5, the dollies on the left side of the picture have more concrete failure than those on the right side. This is expected, as the measured adhesion values from the wet bricks were typically lower than the dry bricks. In Figure 5, SUPRASEC 9611 and SUPRASEC 9584 and castor oil have provided the greatest concrete failure. The Acrylic #1 and Acrylic #2 display the least amount of concrete failure. Figure 6 presents the dolly test specimens that were obtained from the 24-hour polyurea topcoat over both wet and dry primed bricks. Once again, the dry specimens on the left of the picture display more concrete failure 42

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The authors would like to acknowledge Anita Conway and David Balkevitch for their valuable assistance in preparation of the test materials. The authors would also like to thank the Auburn Hills Physical Testing Laboratory and Analytical Testing Laboratory for their services.

References 1

2

3

4

5

Perez, A.P.; Redinger, J.L.; Johnston, J.A. “Performance and Processing Enhancements of Aromatic Polyurea Elastomer Systems Prepared from High 2,4’-MDI” API 2000, Boston, MA. Broekaert, M. “Polyurea Spray Coatings: Technology and Latest Developments”, European Coatings Show 2000, Berlin, Germany Perez, A.P.; Chen, C.C. “Performance Enhancements of Aromatic Polyurea Spray Coatings by the Use of Conventional Primer Systems”, PDA 2000. Camargo, R.; Skok, K. “New Developments for Two Component Urethane Primers”, PACE 2006, Tampa, FL. Johnston, J.A. “An Evaluation of Moisture-cure resins as Primers Under Aromatic Polyurea Elastomer Systems”, PDA 2004.

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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Multipurpose Organosilicone Additive for Waterborne Coatings and Inks Eliminates Regulatory/Performance Trade-Offs

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dvances in waterborne coatings technology in developed countries around the world have been driven by a combination of regulatory restrictions and consumer expectations. Within the past few years, consumers in emerging markets have begun to demand more environmentally friendly products. Some regulations in the Western world, such as the European Union’s REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) initiative, have affected producers exporting paints and inks. The coatings industry, according to Frost & Sullivan1, also will

FIGURE 1 | Water-reducible stoving paint with and without Dow Corning 67 Additive; the new additive significantly reduced the contact angle in 0.1% water compared to other additives.

With Dow Corning 67 Additive

No Additive

Contact Angle

120

Fluoro surfactant Acetylenic diol Dow Corning 67 Additive

80 60 40 20 0 32

34

36

38

40

42

44

Surface Energy of Substrate, mN/m

Traditional Trade-Offs The polarity and cohesive hydrogen bonding between water molecules lead to very high surface tension in water-based systems. High surface tension makes it very difficult for paint to properly wet the surface of substrates with uneven and/or porous surfaces. But, proper wetting is necessary for even coating. Poor wetting causes cratering and an increased defect rate. This problem is magnified if dirt particles and other contaminants are present. When paint is applied to very low-surface-energy, materials such as plastics, air entrapment, crawling, framing and poor adhesion often result. To address these issues, formulators have turned to additives designed to increase substrate wettability and lower surface tension of the coating. In order to achieve complete wetting, coatings must have lower surface tension than the substrate.

Silicone Polyether for Superior Wettability Control

100

have a large impact on technology development around the world. Many manufacturers in India, where there is not yet regulation of VOCs in paint, have been proactive in introducing more sustainable technologies in response to growing domestic demand for greener products. Along with this growing expectation for more environmentally friendly products, consumers expect increasing levels of performance from paint. Waterborne coatings, however, have posed significant challenges to formulators.

Dow Corning’s commitment to sustainability and improving the performance of greener coating formulations led to the development of Dow Corning® 67 Additive, a multipurpose silicone polyether additive designed specifically for all types of water-based coatings, including wood coatings, UV-cured systems and more. Dow Corning 67 Additive is offered as a water-dispersible, 100%-silicone polyether with recommended use levels of 0.1% to 1%. It has a flash point above 100 ºC (212 ºF) and is stable up to 200 ºC (392 ºF). This new silicone additive lowers the surface tension of waterborne coating formulations as measured by con-

By Mustafa Mohamed, Ph.D., Dow Corning Global Application Engineer; and Juan Carlos Corcuera, Dow Corning European Area Application Engineer | Dow Corning, Midland, MI 44

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Ask the Expert Jim Reader Lead Research Chemist

80 70 60 50 40 30 20 10 0

Droplet diameter on PE foil Surface tension mN/m

Surface Tension, mN/m

40 35 30 25 20 15 10 5 0

Do w Co Co m rn pe W in at tit g6 er o Co ro 7 m Ad r g pe an di tit tiv ic or s e ur Co or f ac m ga ta pe ni nt cs tit Co Co 1 or ur m m fa flu c pe pe or ta tit tit ont Co or or su 2 m r p fl f uo ol pe ac ye t r tit an oth or su t1 er po rfa -m lye c od ta th nt ifi er e 2 d -m sil Co od o m xa ifi pe ne ed tit 1 s ilo or xa al co ne ho 2 la lko xy la te

Droplet Diameter on PE Foil, mm

FIGURE 2 | Dow Corning 67 Additive improves wetting by lowering surface tension. These conditions could provide a significant competitive advantage for formulators.

A

Additives added to water at 0.2% addition level with the droplet applied to PE foil.

tact angle. The difference is notable when compared to other commercially available additives (Figure 1). While the new additive significantly enhances wetting properties, it does not have a negative effect on other important properties, such as recoatability. A distinct advantage of this unique silicone polyether is its ability to wet problem surfaces such as PVC and other plastics without the need to add other solvents. At a 0.2% addition level, with no additional solvent required, Dow Corning 67 Additive clearly outperforms many other types of additives on the market (Figure 2). This feature increases the ability of the formulator to meet strict VOC regulations while providing expected appearance and adhesion properties. Because it creates a very low dynamic surface tension, the new additive spreads quickly and evenly. The ability to develop water-based systems that perform as well as traditional solventborne inks and coatings under these conditions could provide a significant competitive advantage for formulators. Ease of use also has been considered when designing this new silicone additive for water-based coatings. Addition is possible at the grind or let down stages of

Q

I’m finding it difficult to control microfoam and pinholes in my airless spray applied topcoats. What would you suggest?

production, or even after all other steps are completed (post-added).

Other Developments The new silicone additive was developed as part of a comprehensive program aimed at helping customers address such coating property issues as gloss enhancement, slip and mar resistance, impact deadening, UV resistance, touch and feel, heat and temperature resistance, water resistance, and marine foul release capabilities. Dow Corning’s R&D efforts are focused on the development of novel silicon chemistries, including additives, resins, resin intermediates and other materials, that will enable formulators to produce sustainable coatings solutions for their customers. The company has a strong commitment to the coatings industry around the world and anticipates launching several innovative solutions in the near future. 䡲

Microfoam is caused by small air bubbles that are caught in the paint film by the spray process and rise too slowly in the drying film, so they remain trapped at or beneath the surface. Pinholes are often caused when these small bubbles break free at the surface, and the film is too viscous to flow back and fill the hole left behind. Pinholes can also appear when coatings are baked; bubbles, initially trapped below the surface, rise as the coating flows under the heat and before it gains viscosity through cross-linking. Deaerators are needed to bring these bubbles to the surface quickly so that the air can be released before the film sets. Molecular defoamers, such as Surfy¯nol® DF110C defoamer or EnviroGem® AD01 defoamer are effective deaerators for many spray applied coatings. These products can also be used in combination with other defoamers, such as Surfy¯nol DF58 defoamer or Surfy¯nol DF70 defoamer, if stronger defoaming is required.

Reference 1

Press Release: “Frost & Sullivan Predicts Gradual Revival of China’s Paint & Coatings Market,” June 28, 2009.

Additional information on Dow Corning’s additives for inks and coatings is available at www.dowcorning. com/coatings.

tell me more www.airproducts.com/ surfactants © Air Products and Chemicals, Inc., 2009 (31892) B40

Visit ads.pcimag.com PA I N T & C O A T I N G S I N D U S T R Y

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T W O

T H O U S A N D

T E N

Additives Handbook By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski

Additives belong to a broad and diffuse category of key components in a coating formulation. They comprise a small percentage in that formulation, usually less than 5%, but their impact is significant. Additive function is almost always very specific in nature. Some additives are multi-purpose; for example, they may be important to the manufacturing process as well as to the coating’s performance. In recent years more multi-purpose additives have been developed, thus allowing the use of fewer additives in many formulations. Occasionally the use of one additive will require the use of another to counter some undesirable effect of the first. Some additives are proprietary products with highly specific functions that work well in some systems but cannot be used in others. In addition, because of the proprietary nature of many additives, their chemical composition is not disclosed. This can make general recommendations difficult. In addition, this lack of structural knowledge

means that additive substitutions cannot be made on the basis of fundamental structural chemistry. In recent years the focus on green technology, lower cost and safer products has led to the introduction of newer additives and chemistries. With a large number of additives available for a particular problem, formulators can find themselves in trouble if the wrong additive is initially selected or added to alleviate or correct a problem. Correct additive selection is important to success, and such selection is made through vendor assistance or years of experience. Please note that there are a number of new nano-sized additives on the market today that are difficult to categorize. Their functions are varied and tend to overlap our traditional categories. For this reason we have included a number of these types under the Nanotechnology section. The following is a brief description of various coating additives along with some generic examples. The majority of additive types are represented.

2010 Additives Handbook ABRASION-RESISTANCE IMPROVERS See Slip Aid, Nanotechnology Abrasion is a phenomenon caused by the mechanical action of rubbing, scraping or erosion. It has two forms, marring or wearing. Mar abrasion is the permanent deformation of a surface, but the deformation does not break the surface. Wear abrasion is removal of a portion of the surface by some kind of mechanical action: wind erosion, sliding back and forth of an object, wear of tires on traffic paint, and so on. The surface removal is gradual and progressive in nature. Abrasion resistance is a combination of basic factors such as elasticity, hardness, strength (both cohesive, tensile and shear strength), toughness, and, especially in the case of wear resistance, thickness. In addition, abrasion resistance is intimately related to scratching and slip. Thus, compounds that enhance these properties will improve abrasion resistance. The nature of the polymeric resin and the pigments affect abrasion resistance. In the case of the pigments, it should be noted that extender pigments are noted for their ability to contribute to a variety of mechanical properties. Examples of compounds that have been used to enhance abrasion resistance include: silica glass spheres, specialty glass spheres such as UVT™ Sunspheres, and similar compounds that improve hardness. Certain silicones and other oils will decrease surface friction, making it easier for objects to slide over the surface and thus reduce wear abrasion. Increasing crosslink density by use of higher functionality oligomers and/or larger amounts of crosslinking agents has been used to improve abrasion resistance. Waxes have also been used to improve slip and thereby abrasion. Hard waxes resist abrasion better than soft materials. Both PE and PTFE waxes function by the ball bearing mechanism, while the softer microcrystalline waxes work via the layer (bloom) mechanism. The use of nano-sized materials in coating formulations can significantly improve scratch resistance. These improvements can be used in 46

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clear topcoats, ink over-print varnishes and pigmented finishes. The commercial availability of nanoparticles allows formulators to obtain new properties that were unachievable in the past, not only in scratch resistance but many other physical performance attributes. For nanoparticles to be of use in transparent coatings, it is critical that aggregates present in the powder be dispersible to their primary particle size in the coating formulation to avoid rapid settling and excessive light scattering. In addition, it is critical that the dispersed primary particles avoid re-aggregation during the coating curing process. Thousands of scratch-resistant coating applications are present in our everyday lives. Examples of these applications include coatings for wood floors, safety glasses, electronic displays, automotive finishes and polycarbonate panels. Improving the mar, scratch and/or abrasion resistance in these transparent coating applications is a major challenge, particularly with regard to not affecting the other performance attributes of the coating.

Inorganic Fillers Incorporation of inorganic fillers into coatings to improve mechanical properties is well known. Drawbacks associated with this approach can include loss of transparency, reduced coating flexibility, loss of impact resistance, increase in coating viscosity and appearance of defects. To overcome these defects, a filler material should impart improved scratch resistance without causing the aforementioned drawbacks. Nanomaterials have the potential to overcome many of these drawbacks because of their inherent small size and particle morphology. Maintaining transparency in a coating containing inorganic filler particles is a challenge. Four properties dictate the degree of transparency in a composite material: film thickness, filler concentration, filler particle size, and the difference in refractive index between the bulk coating and the filler particle.


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2010 Additives Handbook Silica particles, colloidal or fumed, and clays are among the most widely studied inorganic fillers for improving the scratch/abrasion resistance of transparent coatings. These fillers are attractive from the standpoint that they do not adversely impact the transparency of coatings due to the fact that the refractive indices of these particles (fumed silica = 1.46; bentonite clay = 1.54) closely match those of most resin-based coatings. The drawback to silica-based fillers is that high concentrations of the particles are generally required to show a significant improvement in the scratch/abrasion resistance of a coating, and these high loadings can lead to various other formulation problems associated with viscosity, thixotropy and film formation.

Alumina The use of alumina particles in transparent coatings is much more limited even though alumina is significantly harder than silica-based materials and, as a scratch- and abrasion-resistant filler, higher performance at lower loadings is often observed. For alumina particle sizes greater than 100 nm, the high refractive index (1.72) results in significant light scattering and a hazy appearance in most clear coatings. Currently, only high-refractive-index coatings, such as the melamine-formaldehyde resins used in laminate production, can use submicron alumina for scratch resistance and maintain transparency. To use alumina as a scratch-resistant filler in transparent coatings, the particle size must be sufficiently small to overcome its refractive index mismatch. A Physical Vapor Synthesis (PVS) process has been developed that allows production of nonporous crystalline metal oxides having primary particle sizes less than 100 nm at economically viable rates with essentially no byproducts or waste streams. Two grades of aluminum oxide can be produced using the PVS process: NanoTek™ and NanoDur™ alumina. Both grades feature a mixture of γ- and δ-crystal phases and are spherical in shape, but the grades differ in terms of primary particle size. NanoTek alumina has a surface area of 35 m2/g corresponding to a mean particle size of 48 nm, whereas NanoDur alumina has a surface area of 45 m2/g with a mean particle size of 37 nm. There is a proprietary particle dispersion stabilization process that involves specific surface treatments designed to yield nanoparticles that are compatible with a variety of different coating formulations. For example, stable dispersions of metal oxide nanoparticles can be prepared in solvents such as water, alcohols, polar and nonpolar hydrocarbons, plasticizers, and even directly in acrylate monomers with the appropriate surface-treatment process. These surface treatments allow solids levels of up to 60 wt% to be dispersed, and yet maintain a sufficiently low viscosity for ease of blending. The use of highly concentrated, non-aggregated nanoparticle dispersions allows incorporation of the nanoparticles into a coating formulation without substantial dilution of the formulation with the dispersion liquid. This feature is particularly important in 100%-solids coating formulations wherein the nanoparticle is dispersed in one of the reactive monomers. Within a given coating class, formulations that result in harder/ stiffer coatings tend to show greater improvement with alumina incorporation than formulations that lead to softer/more elastomeric coatings. In addition, transparent coating formulations that exhibit crosslinking upon curing, such as UV-curable, 2K polyurethane, and melamine-based coatings, show greater improvement in their scratch resistance upon alumina nanoparticle incorporation compared to transparent coatings that do not crosslink but rather coalesce, such as emulsion-based coatings.

SNC SNC is an abbreviation for silica nanocomposites that are composed of colloidal silica particles with an organic surface modification. These particles, which improve the scratch and abrasion resistance of a variety of coatings including radiation-curable formulations, are produced by a unique process that results in monodispersed, non-agglomerating spheres with a diameter of about 20 nm. The flexible manufacturing process is also capable of producing a broad range of cationic (epoxide) and free-radical (acrylate) radiation-curable oligomeric composite 48

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materials. These products are stable, transparent and have low viscosity, even at a silica loading of 60%. Nanoscale materials for coatings also include complex silicon oxides and aluminum silicates. Nanoparticles of these materials have been incorporated into automotive coating formulations that have good sag resistance. The cured coatings have excellent chip and scratch resistance, outstanding appearance, superior sandability, and resistance to water spotting and acid etching. Some properties, such as scratch resistance, are maintained after accelerated weathering.

Sol-gel It is also possible to improve the scratch- and wear-resistance properties of a coating as well as its photostability/weatherability by the addition of nanoparticles prepared by sol-gel processing. This method has the advantage in that it starts from existing, well-developed formulations to which a sol containing nanoparticles is added. After curing, the modified systems give transparent coatings with high wear and scratch resistance. Very often, hybrid (organic-inorganic) materials are produced by sol-gel. The most common way to produce nanocomposites is to form, in-situ, an inorganic phase by hydrolysis and condensation of alkoxides or alkoxysilanes. A further curing results in covalent bonding between the organic and inorganic phase.

ABSORBENTS Absorption is a process wherein a material is taken up and held, or retained, by another material. The material taken up is called the “absorbate” and the material that retains the material from the absorption process is called the “absorbent.” Thus, absorbents are materials that are able to take up another material with the formation of a homogeneous mixture. For example, cotton fibers will take up moisture, charcoal will take up a gas, baking soda will take up odors, silica gels will take up moisture; certain pigments, clays or extenders will take up oils and others will take up moisture; and so on. This should be contrasted with adsorption, which is a surface phenomenon and wherein adsorbed molecules can have markedly different properties than those of absorbed molecules. Compounds such as zeolites or molecular sieves are adsorbents that take up compounds by the adsorption process (See Moisture Scavenger).

ACCELERATORS See Hardeners These products increase the epoxy-amine reaction rate and subsequently reduce the possibility of undesired blushing or blooming reactions. Controlled use of the amount and type of accelerator ensures minimal impact on the cured binder performance. Although there are numerous products capable of accelerating epoxy-amine reactions, the most commonly used are: tertiary amines (e.g., DMP-30 = 2,4,6-tris-[dimethylaminomethyl]-phenol), phenol derivatives (e.g., nonylphenol), alcohols (e.g., benzyl alcohol) or acids (e.g., salicylic acid). Be aware that adding accelerator will significantly reduce the pot-life of the binder system.

ACID CATALYSTS See Catalysts Acid catalysts are used to accelerate chemical reactions. Strong acids such as p-toluene sulfonic acid (PTSA) are frequently used. Also used are catalysts based on dodecylbenzene sulfonic acid (DDBSA) and hexafluorophosphoric acid. In using strong acids as catalysts, acid strength does not necessarily influence the cure rate but it does affect some film properties. The most widely used of the strong acids is PTSA. Weaker acids, such as butylphosphoric, those based on aromatic phosphates and various carboxylic acids, are also used in some coatings systems. Blocked acid catalysts are also used for many crosslinking reactions.

ACID SCAVENGERS Acid scavengers remove the small amounts of acid that are formed during the lifetime of a coating or ink. For example, when vinyl



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copolymers are aged small amounts of hydrochloric acid are formed as they age. An acid scavenger reacts with the acid, which removes it from the system so it cannot cause harm to the coating, substrate or abutting objects. Compounds such as cycloaliphatic epoxides and soybean oil epoxide, which readily react with strong acids, are examples of acid scavengers.

ADHESION PROMOTERS See Coupling Agents Adhesion promoters improve a coating’s ability to withstand mechanical separation from a substrate. That is, they improve adhesive strength. Quite often these compounds contain two different functional ends, one of which will interact with the substrate and the other that will interact with the coating binder. Examples of the various coupling agents are the silanes, which are trihydrolyzable; the titanates, which can be mono-, di-, and tetrahydrolyzable; and the chromiums, which are complex in nature. For metal surfaces that are to be coated, this is particularly important because metals, as a class, are unstable. The pure metal is always oxidizing to the metal oxide on the surface of the metal substrate. Exposure to moisture, oxygen and salts accelerates the process. Almost all coatings contain microvoids through which oxygen, small molecules like water, and ionic materials can diffuse. If the coating can remain bonded to the metal, then the damage done by these diffuse agents will be nonexistent. In other words, corrosion can be prevented. It is, therefore, very important to do all that is possible to maximize adhesion. For some materials this involves a mechanical roughening of the substrate surface to increase the surface area for physical absorption. Chemical pretreatments such as zinc/iron phosphate and various other materials have also been used because tightly bound phosphated surfaces will retard access to the metal and, therefore, impede corrosion. Typically, organofunctional silanes have been used in coatings as adhesion promoters because they provide a polar functional group to contribute to increased bonding to a mineral substrate. They also are hydrolyzable and provide wetting ability and surface activity. The silanes are moisture sensitive and will hydrolyze over time to silanols. This is not a problem in solventborne coatings systems but can cause problems for waterborne systems. The silanes react with both the polymer and the substrate to form covalent bonds across the interface. Silane adhesion promoters are used in urethane, epoxy, acrylic and latex systems. Receptive inorganic surfaces are those that have hydroxyl groups attached to elements such as Si, Al, Ti and Fe. Nonreceptive surfaces, such as boron, and alkaline earth oxides, do not form stable covalent bonds with silanols. A number of different commercial silane coupling agents are used in coatings. Levels that range from 0.05-1.0% are generally effective. Methacrylic phosphate monomers that improve adhesion to metal, concrete, glass and other inorganic substrates and that can be used in both water- and solventborne formulations are available. Some methacrylic phosphate monomers improve metal adhesion and also significantly improve corrosion resistance. There are also acrylic phosphate functional monomers that improve adhesion to various metal substrates. The acrylic reactive group provides a higher reaction rate in UV- and EB-curable applications. Other adhesion promoters that are in the marketplace are titanates (such as isopropyl tris-[N-ethylaminoethylamino] titanate), zircoaluminates, zirconates, aryl/alkyl phosphate esters and proprietary metal organic compounds. The titanates and zirconates suffer from moisture sensitivity as well, so caution is necessary when using them with waterborne systems. Neo-alkoxy products are claimed to not have this problem. Alkyl/aryl phosphate esters, zircoaluminates and the metal organic promoters are stable in waterborne coatings. They are quite different in chemical nature and therefore the formulator needs to evaluate them separately. Epoxy/methoxy functional additives are effective in promoting adhesion of a variety of coating systems to glass, aluminum and steel. Methacrylate/methoxy functional additives improve adhesion of free radical cured resins, such as polyacrylates, to inorganic substrates. Epoxy functional silanes improve adhesion and water resistance of a variety of coating systems to inorganic substrates. Amine/methoxy

functional additives improve adhesion and water resistance of coatings and adhesives when bonded to glass or metal substrates.

Powder Coatings The same precautions regarding clean substrates and pretreatments that apply to liquid coatings are advised for powder coatings. Adhesion promoters such as the silanes and titanates may also be used to enhance adhesion. Silanes designed for use in powder coatings have an organo functionality that has an affinity for the powder resin system. The organo-silane must orient itself at the coating-substrate interface. The choice of organo-silane is usually governed by the resin system, and experimental screening is advised to determine which promoter provides the most improvement. Adhesion promoter types commonly used in powder include mercapto-silanes, amino-silanes, carboxyl/hydroxyl-silanes, and carboxyl-silanes.

Plastic Substrates Due to high chemical stability, low price, excellent balance of physical properties, possible recycling, etc., the amount of polypropylene (PP) and thermoplastic olefin (TPO) consumed by automotive parts, household electrical appliances and molded general goods businesses is increasing. However, PP and TPO are materials with low surface energy that make painting and adhesion problematic, hence chlorinated polyolefin (CPO) has found wide use as an adhesion promoter. Solventborne CPOs have traditionally been used. Excellent adhesion between TPO substrates and CPO can be obtained as the result of good wetting and higher dispersion interaction, which are affected by the properties of the CPO’s chlorine content, crystallinity, melting temperature, molecular weight and its polydispersity. There are several factors that can affect the performance of a CPObased adhesion promoter. Application parameters play a significant role in designing a system that will provide optimum adhesion performance. Of particular importance is the temperature at which a coating applied to a PP or TPO part is cured or baked. In addition, substrate and CPO composition can influence overall adhesion performance. Coating bake temperature is the temperature at which the coating applied to the TPO part is cured. Coating bake temperature can have an effect on the interaction between a CPO-based adhesion promoter and the surface of TPO, which can affect performance. For best results, coating adhesion is enhanced when the coated TPO parts are baked at temperatures over 100 ˚C, given the same coating type. However, CPObased adhesion promoters are successfully used in applications, such as automotive refinish applications, where the coating is air-dried or baked at temperatures lower than 100 ˚C. The chemical and physical properties of the CPO can also have a significant effect on adhesion performance. Addition of co-resins to CPOs can enhance adhesion, reduce blistering, and improve the appearance of coatings applied over the adhesion promoter layer. CPOs have limited compatibility with most resin types, but unlike conventional coatings this may not be detrimental to performance. CPOs promote adhesion best when they are at the interface of the substrate and the coating applied over the substrate. This means that a formulated adhesion promoter system with a CPO and borderline compatible co-resin may actually allow the CPO to reach the interface more readily. A number of co-resin types can be used with CPO, including acrylic, acrylic-modified alkyds, polyesters and others. The level of CPO used in the formulation will be dependant upon the substrate, coating type and required performance properties. Research efforts are focused on waterborne coatings applicable to TPO substrates that coalesce well at baking temperatures as low as, or lower than, 80 ˚C (176 ˚F) in order to save energy costs and to avoid thermal deformation of TPO substrates at the higher temperatures. Chlorine-free adhesion promoters are also being used and are highly desirable.

To view the rest of the definitions in the Additives Handbook, visit www.pcimag.com or e-mail Andrea Kropp at [email protected] to purchase the CD. PA I N T & C O AT I N G S I N D U S T RY


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