Flexible basecoat/clearcoat coating compositions

Claim 1

A flexible basecoat/clearcoat coating composition, useful as automotive finish coats on metal and plastic substrates, which is characterized in that: I. The clearcoat composition comprises: (A) hydroxy-containing urethane modified polyester (i) having a number average molecular weight (M n ) of between about 1000 and about 10,000, (ii) having a hydroxyl number of between about 30 and about 200, and (iii) containing between about 1 and about 10 urethane groups per molecule, and being made from reactants comprising: (1) urethane modified diol made by reacting: (a) diol; and (b) diisocyanate, wherein said diol and said diisocyanate are reacted in a molar ratio of from about 4:1 to about 4:3; (2) polyol comprising at least about 5 weight percent triol; and (3) acid component selected from dicarboxylic acids and anhydrides thereof; (B) amine-aldehyde crosslinking agent; and II. the basecoat composition comprises: (A) hydroxy-containing urethane modified polyester (i) having a number average molecular weight (M n ) of between about 1000 and about 10,000, (ii) having a hydroxyl number of between about 50 and about 250, and (iii) containing between about 1 and about 7 urethane groups per molecule, and being made from reactants comprising: (1) hydroxy functional polyester prepared from a mixture of (a) polyhydroxy materials comprising diols and triols and (b) acid component selected from dicarboxylic acids and anhydrides thereof; and (2) diisocyanate; wherein in forming the hydroxy functional polyester, the proportion of reactants (a) and (b) are selected so that the OH/COOH ratio is from 6:2 to 6:5; and wherein in forming the modified polyester the proportion of hydroxy functional polyester (1) and the diisocyanate (2) are selected so as to provide from 4:1 to 10:1 hydroxyl/isocyanate groups; and (B) amine-aldehyde crosslinking agent; and (C) pigment; and wherein either or both of said basecoat composition and said clearcoat composition individually comprises 0-60 weight percent, based on the total weight of (A) and (B) of each said composition, of a linear polyurethane having a number average molecular weight of between about 15,000 and about 40,000.