Control of metallic appearance in automotive cast paint films

摘要

A thermoplastic and thermoformable pigment-containing metallic automotive paint is solvent cast and dried to form a finished metallic automotive paint coat for a decorative film used in a thermoforming process to form an exterior paint layer on a molded plastic automotive body panel. The paint coat contains a pigment uniformly dispersed in a polymeric binder material preferably comprising an alloy of a polyvinylidene fluoride (PVDF) copolymer and an acrylic resin in which the PVDF copolymer is provided as a dispersion in the acrylic resin. Preferably, the dispersed form of the PVDF copolymer has a particle size of about eleven microns or less, and more preferably a mean particle size range of about 3 to about 4.5 microns. The dispersion ratio is preferably from 80% to 20% PVDF copolymer and from 20% to 80% acrylic resin, respectively, by a weight. A low molecular weight form of the PVDF copolymer is preferred and characterized by a melt viscosity of 17,000 to 20,000 poise at 230 DEG C. Reflective flakes are uniformly dispersed in the polymeric dispersion material and the dispersion form of the PVDF copolymer inhibits parallel orientation of the reflective flakes to produce a more random orientation that achieves a metallic appearance similar to standard spray painted metallic paint coats.