Beta-hydroxyalkylamide cured acid polymer/polyepoxide powder coating

Claim 1

A thermosetting powder coating composition comprising: (1) a co-reactable particulate mixture of: (a) from about 35 to about 85 percent by weight based on weight of resin solids of a carboxylic acid group-containing polymer having a Tg in the range of about 35° C. to 100° C.; (b) from about 2 to about 45 percent by weight based on weight of resin solids of a polyepoxide having a 1,2- epoxy equivalency of greater than 1.0; and (c) a beta-hydroxyalkylamide of the structure: ##STR4## where R 1 is H or C 1 -C 5 alkyl; R 2 is H, C 1 -C 5 alkyl or ##STR5## where R 1 is as described above and A is a chemical bond or monovalent or polyvalent organic radical derived from saturated, unsaturated or aromatic hydrocarbon radicals including substituted hydrocarbon radicals containing from 2 to 20 carbon atoms, m equals 1 to 2, n equals 0 to 2 and m+n is at least 2, and the equivalent ratio of beta-hydroxyalkylamide equivalents plus epoxy equivalents to carboxylic acid equivalents being within the range of 0.6 to 1.6:1; and (2) a crystalline carboxylic acid group-containing material selected from the group consisting of an aliphatic polycarboxylic acid containing from 4 to 20 carbon atoms, a polymeric polyanhydride other than carboxylic acid group-containing polymer (a), a polyester other than carboxylic acid group-containing polymer (a), having a number average molecular weight from about 300 to about 1,500 and an acid equivalent weight of from about 150 to about 750, and mixtures thereof