PROCESS FOR FORMING OVERCOAT

摘要

The invention provides a process for forming an overcoat by the two-coat one-bake method wherein a base coat composition and a clear coat composition are applied to a substrate wet-on-wet and thereafter cured at the same time by heating, the process being characterized in that the base coat composition is a coating composition consisting primarily of a hydroxyl-containing resin, an amino resin, a pigment and an organic solvent, the clear coat composition being a coating composition comprising: (A) at least one resin selected from the group consisting of (i) a resin having at least one epoxy group and at least one hydroxyl group in the molecule, (ii) a resin mixture of (ii-1) a resin having at least two epoxy groups in the molecule and (ii-2) a resin having at least two hydroxyl groups in the molecule, (iii) a resin having at least two epoxy groups in the molecule, and (iv) an any mixture thereof~ (B) a crosslinking agent comprising a compound having at least two noncyclic acid anhydride groups and represented by the formula (I) wherein R is a monovalent hydrocarbon group having 2 to 50 carbon atoms, R' is a bivalent hydrocarbon group having 2 to 50 carbon atoms, the hydrocarbon groups R and R' containing or not containing an ether linkage, urethane linkage or ester linkage, and n is an integer of 1 to 500, and (c) a curing catalyst.