High solid coating composition and method for forming topcoat using same

An organic solvent-based heat-curable high solid coating composition comprising: (A) a carboxyl-containing compound having an acid value of 50 to 500 mg KOH/g wherein 20 mol% or more of the carboxyl groups are silylated carboxyl groups, (B) at least one epoxide selected from (B-1) an epoxy-, hydroxyl- and hydrolyzable alkoxysilyl-containing vinyl polymer, (B-2) the vinyl polymer (B-1) wherein 20 mol% or more of the hydroxyl groups are silylated hydroxyl groups, and (B-3) an epoxy compound having a number average molecular weight less than 1,000, and (C) a crosslinked particulate polymer, the composition having a solid content of 65 wt.% or more; and a method for forming a topcoat using the composition. The composition of the invention has a sufficiently high solid content, is capable of forming a coating film with high resistance to acids and the like, and is excellent in low-temperature curability, storage stability and recoat adhesion.