Development of a New High Orientation Paint System to Achieve Outstanding Real Metallic Designs

Silver metallic colors with thin and smooth aluminum flake pigments have been introduced for luxury brand OEMs. Regarding the paint formulation for these types of colors, low non-volatile(NV) and high aluminum flake pigment contents are known as technology for high metallic appearance designs. However, there are two technical concerns. First is mottling which is caused by uneven distribution of the aluminum flake pigments in paint film and second is poor film property due to high aluminum pigment concentration in paint film. Therefore, current paint systems have limitation of paint design. As a countermeasure for those two concerns, we had investigated cellulose nanofiber (CNF) dispersion liquid as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it has strong hydrogen bonds with other fiber surfaces in waterborne paint. The CNF shows similar viscosity result with conventional water borne paint though CNF contents is less than 1wt% and NV is less than 5wt%. Furthermore, CNF's surface bonds with isocyanate resin makes strong fiber-reinforced layer caused by penetration from the clearcoat layer. We made a prototype silver color with this new CNF low NV waterborne paint system with vapor deposition aluminum pigments. It can exceed our conventional silver color's Flip Flop (FF) with marketable quality.