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, by sequentially applying a primer surfacer, a base coat composition, and a 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: 40 to 95% by weight of a highly branched acrylic polymer having a hydroxyl, carboxyl and/or other crosslinkable functional group monomer content of about 1 to 65%; and 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 multi-layered coating film 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.