Appliance coating developments

Application of Topcoats Appliance Coating Specifications Recent Developments Flow Coat Conversion Electrocoating High Solids Powder Coatings Low Energy Cure Coatings Coatings to Replace Porcelain Future... 

The first successful waterborne flow coat for appliances was developed by the Glidden Division of SCM and applied to dryer drums and bulkheads. Emissions were reduced by 80%, and fire hazards associated with the solvent system were reduced significantly. 

Sherwin-Williams, the largest U.S. coatings supplier overall, is the top U.S. producer of TS coatings. They have been leaders in industrial urethane finishes and are active in PC, WB, RC, and HS coatings. Recent research and development in the cathodic ED field has led to the introduction of several new products for the automotive and appliance industries. 

Appliances used to be essentially 100% metal and the appliance industry was faced with such problems as corrosion, heat or electrical conductivity, and limitation of design flexibility. Fortunately, our industry recognized these problems and developed plastics that helped make better appliances at lower costs. In many industries the solvents used m protective coatings created... 

Thus, numerous low-emission paints have been developed, including high-solids paints, waterborne paints, aqueous dispersions for industrial use, powder coatings, and radiation-curing coatings. At the forefront in adopting these environmentally friendly products is heavy industry, in particular the automobile and household appliance industries. Medium-sized and smaller businesses will profit from this experience, adapting it for their own needs. 

Coating powders for exterior use are mainly based on the SP-TGIC system. Of some importance is the SP-PUR system, i.e., the combination of hydroxy-functional polyester resins with caprolactam-blocked isocyanate adducts (primarily based on isophorone diisocyanate). The newly developed SP-HAA and SP-glycidyl estermix systems avoid the problems of TGIC as regards toxicology. Acrylic resins are of importance mainly in the United States (AY-PUR) and in Japan (AY-DDA). The AY-PUR system is used for automotive components and in domestic appliances. The PUR systems based on uretdione (a dimerization product of isocyanates) do not... 

The choice of binders for the topcoat depends on the end use of the coil-coated metals. Acrylic topcoats were developed earliest, and are widely used indoors for surfaces that are not exposed to water, chemicals, or mechanical stress. Polyester coil coatings provide a good general-purpose finish, and can be used for a wide range of applications (e.g., car interiors and accessories, caravan exteriors, domestic appliances). Tough, abrasion-resistant, and durable general-purpose finishes can be formulated with polyurethane and polyester resins in combination. 

Manufacturers produce more than 8 billion pounds of BPA every year, making it one of the most common industrial chemicals produced worldwide (Rubin 2011). Plastics made with BPA are used in many consumer products, including food and beverage containers, toys, eyeglasses, computers, kitchen appliances, and medical equipment. Epoxy resins containing the chemical are used in dental work and in metal coatings for food cans, pipes, cars, dairy equipment, office equipment, and other metal products. BPA and its derivatives are also used in flame retardants (tetrabromobisphenol A), in engineering applications such as laminates for printed circuit boards, and as color developers in thermal receipt paper (Birnbaum et al. 2012). Some, but not all, plastics that are marked with recycle codes 3 or 7 may be made with BPA. 

Unsaturated polyester is one of the most versatile thermosets in that it is used in the fabrication of a broad range of products, including structural parts of automobiles, building materials, coating materials, electrical parts, appliances, and boat hulls. Consequently, a variety of resin formulations have been developed, depending on specific applications as well as fabrication processes. Unsaturated polyester and... 

The paint is further thinned with Solvesso 100 to a viscosity of around 25 seconds for application. This will require typically 15-20% solvent, giving a volume solids at application of circa 33% and this factor, probably above all others, has led to the replacement of acrylamide acrylics by powder coatings for the coating of cabinets of domestic appliances in Europe and North America. If it were not for the issue of VOC reduction, this technology would continue to compete successfully with powder coatings and will probably do so in developing countries where VOC constraints are not yet an issue. 

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