Powder paint blend of epoxy and amide-functional copolymer and anhydride-functional copolymer

Claim 1

In a thermosettable powder paint which exclusive of pigments, catalysts, antistatic agents, and plasticizers, the same being conventional non-reactive additives to a thermosettable powder paint, consists essentially of a coreactable particulate mixture of A. an epoxy-functional copolymer of monoethylenically unsaturated monomers consisting essentially of about 5 to about 20 weight percent of a glycidyl ester of a monoethylenically unsaturated carboxylic acid and about 80 to about 95 weight percent of other monoethylenically unsaturated monomers, and having a glass transition temperature in the range of about 50° C. to about 90° C. and a molecular weight in the range of about 1500 to about 15,000, B. as crosslinking agent, an anhydridefunctional copolymer, C. 0.05 to about 4 weight percent of a non-reactive polymeric flow control agent based on the weight of said coreactable particulate mixture, the improvement wherein: 1. said epoxy-functional copolymer is qualitatively difunctional and said other monoethylenically unsaturated monomers consist essentially of difunctional monomers selected from the group consisting of acrylamide and methacrylamide in an amount comprising about 2 to about 10 weight percent of said copolymer and monoethylenically unsaturated monomers consisting essentially of monofunctional monomers selected from the group consisting of esters of a C 1 - C 8 monohydric alcohol and acrylic acid, esters of a C 1 - C 8 monohydric alcohol and methacrylic acid and C 8 - C 12 monovinyl hydrocarbons, and 2. said anhydride-functional copolymer has molecular weight in the range of about 1500 to about 15,000 and is a copolymer of about 5 to about 20, weight percent of an anhydride of an olefinically unsaturated dicarboxylic acid and about 80 to about 95 weight percent of alpha-beta, monoethylenically unsaturated, quantitatively and qualitatively monofunctional monomers selected from the group consisting of esters of a C 1 - C 8 monohydric alcohol and a monocarboxylic acid selected from acrylic acid and methacrylic acid and C 8 - C 12 monovinyl hydrocarbons, said esters of a C 1 - C 8 monohydric alcohol and a monocarboxylic acid comprising in excess of 50 weight percent of said anhydride-function copolymer, and is present in said coreactive particulate mixture in an amount that provides about 0.4 to about 1.4 anhydride groups per functional group on said epoxy-functional copolymer.