Method of forming a multi-layer coating on automobile bodies without a primer bake

Abstract

This invention relates to a method for forming a multi-layer coating, comprising sequentially applying a layer of primer coating composition, a layer of base coat composition, and a layer of clear coat composition on an automotive substrate in a wet-on-wet-on-wet manner, and simultaneously curing the applied three layers together in a single baking step. The primer surfacer comprises a film forming binder, a volatile organic liquid carrier, and pigment(s); and the binder contains about (a) 40 to 95% by weight of a caprolactone-modified highly branched acrylic polymer having a hydroxyl and/or carboxyl monomer content, all or part of which has been reacted with caprolactone, of about 1 to 65% by weight and a weight average molecular weight of about 10,000 to 150,000; and (b) 5 to 60% by weight of an aminoplast resin crosslinking agent. The composition is essentially free of crosslinked nonaqueous dispersion resin particles or crosslinked microgel resin particles or both. The resulting cured multi-layered coating has excellent aesthetic appearance, strike-in resistance, chipping resistance, sag resistance, and film build even when formed in a three wet layered application method.

Dependencies are inferred from the claim text.