Coatings formulators work directly with pigment suppliers to develop and commercialize new special effect pigments to generate exciting color spaces that accentuate the bodylines of new vehicles. Effect pigments are the fastest growing segment of the high performance pigment market, and in 2015 were present in 70% and 65% of automotive colors for new builds in the Americas and Europe, respectively, according to Jane Harrington, manager of color styling with PPG Automotive OEM Coatings. “While neutral colors such as white, black, and silvers still dominate most of the automotive color palette, deep, rich, highly chromatic blues, greens, oranges, and reds have begun to find their place in the automotive world as well,” says Jason Kuhla, manager of technical service & product application with Silberline Manufacturing. “Special effect pigments that provide brilliance and ‘pop’ can help to create a look that stands out among the sea of color monotony, and appeal to those consumers who wish to stand apart from the crowd,” he adds. Allen Brown, advanced development and mastering manager in the Color and Material Design group of Ford Motor Company, agrees that while there will always be niche colors for special applications, overall there seems to be a balancing of colors to round out a complete selection, with a shift away from achromatic colors to a more sophisticated, balanced palette. For some applications, designers are seeking to create a value-added appearance by increasing the brilliance and reflectivity of metallic finishes while maintaining a smooth, non-sparkling appearance, according to Michael T. Venturini, global marketing manager, Coatings, Sun Chemical Performance Pigments.
To achieve the desired appearance, most pigment flakes must be oriented in a specific manner within the coating. Their particle size also impacts the way they interact with light; larger particles provide more sparkle and iridescence, but the dimensions are limited to avoid impacts on gloss and other appearance properties. The industry is pushing the limits in this area, according to Paul Czornij, technical manager with the Color Excellence Group of BASF Coatings, and is seeking as much coarseness as the color can allow yet still providing a smooth and glossy look. The rheology of effect pigments, particularly in high solids, solvent-based systems, also influences their final appearance properties. On the other hand, there is a desire for smoother glass-like finishes, which has led to greater use of finer particle sizes to help deliver a quality liquid appearance in many colors, according to Brown. However, smoother finishes that give strong travel (bright face and dark side-tone) are difficult to achieve with electrostatic bell application (preferred for its greater transfer efficiency), which tends to make flakes stand up and give a more granular appearance, according to John Book, product line manager with Viavi. “Smaller particle sizes and size distributions also have a negative impact on color capability and metallic orientation, so such advances are far from simple,” asserts Frank Maimone, manager of pigment and color technology for the Color Development group of PPG Automotive OEM Coatings.
The shape of the vehicle has a significant impact on which effect pigments are used. For instance, fine/bright effect pigments that give coatings brightness with higher travel are preferred for vehicles that have a more interesting, free-flowing form, while for trucks, which are more slab-sided, coatings with more sparkle are frequently used, according to Jerry Koenigsmark,* who was manager of technical color design for PPG Automotive Coatings in North America. “For many of the new car designs targeting a younger consumer base, there is a push towards highly chromatic colors that employ colored aluminum pigments, mica pigments, glass flakes, and interference pigments,” says Kuhla. He also notes a shift in the wheel coatings market, where black is becoming more popular at the expense of traditional silvers.
For car interior trim parts, chrome-like coatings are used to create a value-added look and add haptic properties to simple plastic and other components. Auto parts and accessories (APA) also tend to be dominated by silvers, and many of these coatings contain pigments manufactured using physical vapor deposition (PVD) processes. In addition, many interior coatings are intended to provide attractive haptic properties. Because they are often single-layer systems, the effect pigments must have high resistance to body oils, perspiration, lotions, cosmetics, and other chemicals, according to Jörg Krames, vice president for global key account management with Eckart. He also notes, in these applications, liquid coatings compete with powder coatings and alternative technologies such as in-mold decoration with foils.