Paint & Coatings Industry - March 2008 - (Page 43)

as supplied, is 373 g/L (EPA Method 24). The VOC after using recommended dilution directions had an average of 389 g/L. The low-viscosity siloxane-based materials enable formulators to prepare products with VOCs ranging from 50 to 160 g/L and the ability to use VOC-exempt solvents if necessary for dilution. Table 3 | ASTM test result data. Test Elongation Pencil hardness Crosshatch adhesion Procedure ASTM D 522-93a ASTM D 3363-74 ASTM D 3359 Silicone Epoxy I 35% 2H 5B Silicone Epoxy II >35% 2H 4B Commercial Polysiloxane 7% 4H 4B Experimentation The silicone epoxy formulations with acid-functional acrylic were prepared by grinding the pigment in the acrylic resin. Additives were used for defoaming and flow. No time was devoted to finding the ideal additive package or solvent compatibility, which resulted in some surface defects that can be easily eliminated. The viscosity of the grind base was adjusted by adding low-viscosity siloxane. The silicone epoxy was used as the crosslinker and mixed as the “B” component. There were no UV absorbers or stabilizers added to the silicone-based systems. The formulation was designed to evaluate the stability of the silicone epoxy and silicone amine crosslinkers (Table 2). The non-isocyanate-based systems used the same acid-functional acrylic as part A. This system had UV stabilizers added to increase exterior durability. Panels were prepared by using a wire-wound draw down bar and in some cases a bird blade as the applicator. The substrate used was non-treated cold rolled steel and non-treated aluminum from Q-panel. Panels were exposed 45°south in South Florida (Q-Panel). One panel was sent back after exposure each year for evaluation. The edges and backs were taped on the steel panels to prevent backside corrosion. Panels were evaluated after washing half with a wet sponge. The accelerated weathering test was completed by using QUV-A bulbs with a 4-hour UV exposure cycle with a 15-minute spray and a 4-hour condensation cycle. silicone acrylic formulations should last 30-250% longer than urethane technologies. This in itself would decrease VOC emissions that are associated with application and cleanup; in addition the new addition curing technologies can be formulated with at least 50% less VOC than commercially available urethanes. There were 48 papers presented at NACE 2007 and seven papers presented at PACE-2007 focusing on development/utilizing green technologies. The International Coatings Exposition in October, 2007, which adopted the “Clean–Lean–Green: Innovative Solutions for the Global Coatings Community,” as its theme, speaks of how companies and, more specifically those in product development, are proactively looking at ways of protecting our environment and the environment of our neighbors. Reducing VOCs, using less-harmful raw materials and increasing coating durability are the beginning steps to preserve a cleaner more desirable place for our children. Special thanks to Joel D. Kennard for his support in evaluation of analytical results. Special thanks to the following companies for their support with raw materials and formulation guidance: Cook Composite and Polymers www.ccponline.com Rohm and Haas www.rohmhaas.com References 1 Conclusion The use of a coating prepared from silicone epoxy I and an acid-functional acrylic had ~30% increase in gloss retention and better corrosion protection than commercially available polyurethanes and non-iso systems. The lower-functional silicone epoxy system (silicone epoxy II) has 2.5 times better gloss retention after 4 years exposure over non-treated aluminum and after 3 years exposure over non-treated cold rolled steel. However the corrosion protection matched the urethane. The silicone amine/epoxy system had better gloss retention than urethane in QUV and South Florida with similar corrosion resistance. If corrosion and gloss/color retention were the only measure for the durability of a coating then the 2 3 4 5 6 Hamberg, J. Going Green with Your Painting Company, PACE, 2007. Challener, C. The Grass Really Can Be Greener. J. of Ctgs. Tech. 2007, 1. Oldering, Dr.; Hayward, G. Resins for Surface Coatings, Volume 1, 1987 Borst, S.; Laubender, T.; Snyder, S.; Greene, J. Adding Value to Industrial Coatings by Using Epoxy Functional SiliconeResins. PCI 2004, 10. Chang, B.; Guy, C. Evaluating Maintenance Coatings for Offshore Platforms in Gulf of Mexico. J. of Protective Ctgs. and Linings 2000.Volume 17, Number 2. Laubender, T.;Greene, J. Adding Value to Coatings by Using Unique Organo Functional Silicone Hybrids, The 8th Nürnberg Congress European Coatings Show, 2005. For further information, visit www.wacker.com. PA I N T & C O A T I N G S I N D U S T R Y 43 http://www.ccponline.com http://www.rohmhaas.com http://www.wacker.com

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Viewpoint Industry News Calendar of Events Company News Mergers and Acquisitions Names in the News Marketplace Quarterly Stock Watch Reaching Strict VOC Requirements With Outstanding Durability for Industrial Maintenance and Marine Coatings A Unique Fungicide for Wood-Filled Plastic deSigns of the Times: Slacking Off! From Rocks to Nanos Shear-Free Dispersion Process Fluorinated Oxetane Oligomers as Versatile Intermediates for Polymer Modification The Effects of TPO Composition on Adhesion and Proposed Chemical Mechanism Supplier Showcase Color Management Materials Watch Products Classifieds Advertiser Index

Paint & Coatings Industry - March 2008

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