High solids coating composition adapted for use as automotive topcoat--#1

Claim 1

A thermosetting coating composition adapted for low temperature bake applications which contains greater than about 60 percent by weight of nonvolatile solids, and which exclusive of pigments, solvents and other nonreactive components, consists essentially of: (A) a copolymer bearing pendant epoxy functionality, having a number average molecular weight (M n ) of between about 1500 and about 10,000 and a glass transition temperature (Tg) of between about -25° C. and about 70° C., said copolymer consisting of between about 10 and about 30 weight percent of monoethylenically unsaturated monomers bearing glycidyl functionality and between about 90 and about 70 weight percent of other monoethylenically unsaturated monomers; (B) at least one organophosphate ester having the formula: ##STR3## wherein n=1 to 2 and R is selected from the alkyl, cycloalkyl or aryl groups; (C) an amine-aldehyde crosslinking agent; and (D) up to 45 weight percent based on the total weight of (A), (B), (C), and (D) of a hydroxy functional additive having a number average molecular weight (M n ) of between about 150 and about 6,000, said organophosphate ester being included in said composition in an amount sufficient to provide between about 0.67 and about 1.4 equivalents of acid functionality for each equivalent of pendant epoxy functionality on said copolymer and said amine-aldehyde crosslinking agent being included in said composition in an amount sufficient to provide at least about 0.67 equivalents of nitrogen crosslinking functionality for each equivalent of hydroxy functionality included in said composition either as a hydroxyl group on said hydroxy functional additive or as a result of esterification of said copolymer during cure of said coating composition.