High solids coating composition of an acrylic polymer a polyester polyol and an alkylated melamine crosslinking agent

Claim 1

A high solids coating composition comprising at least 40% by weight of a binder of film-forming constituents and up to 60% by weight of a nonaqueous liquid carrier; in which the film-forming constituents consist essentially of about (1) 10-50% by weight, based on the weight of the binder, of an acrylic polymer consisting essentially of (a) 10-50% by weight, based on the weight of the polymer, of styrene, methylmethacrylate or mixtures thereof; (b) 30-70% by weight, based on the weight of the polymer, of an alkyl methacrylate, or an alkyl acrylate each having 2-12 carbon atoms in the alkyl group, and (c) 15-50% by weight, based on the weight of the polymer, of a hydroxyl alkyl acrylate or methacrylate having 2-4 carbon atoms in the alkyl group; and the polymer having a number average molecular weight of 500-20,000; (2) 10-60% by weight, based on the weight of the binder, of a polyester polyol having a number average molecular weight of 1500 or less and an acid number of 20 or less which is the reaction product of (a) neopentyl glycol and at least one other hindered diol containing two methylol groups wherein each methylol group is attached directly to a cycloaliphatic or aromatic structure or to a tertiary carbon atom, the molar ratio of neopentyl glycol to hindered diol being 2:1 to 6:1, and (b) a mixture of aromatic and aliphatic dicarboxylic acids wherein the molar ratio of aromatic acid to aliphatic acid is from 1.5:1 to 10:1, wherein the molar ratio of (a) to (b) is from 1.3:1 to 1.9:1 and wherein the polyol has a hydroxy content of about 3.0-10.0% by weight; (3) 15-40% by weight, based on the weight of the binder, of a fully or partially alkylated melamine formaldehyde crosslinking agent having 1-4 carbon atoms in the alkyl group.