Powder coating compositions comprising a blend of coreactive polymers - II E

Claim 1

In a thermosettable powder paint which exclusive of pigments, antistatic agents, and plasticizers, the same being conventional non-reactive additives to a thermosettable powder paint, consists essentially of a coreactable particulate mixture of 1. an epoxy-functional copolymer of monoethylenically unsaturated monomers having a glass transition temperature in the range of 40°C. to 90°C., 2. a carboxy-functional compound as crosslinking agent for said copolymer, and 3. 0.05 to 4.0 weight percent of a non-reactive polymeric flow control agent based on the weight of said coreactable particulate mixture, the improvement wherein: A. said copolymer is a difunctional copolymer of about 5 to about 20 weight percent of a glycidyl ester of a monoethylenically unsaturated carboxylic acid, about 2 to about 10 weight percent of a monohydroxy ester of a C 2 - C 4 diol and acrylic or methacrylic acid, and about 70 to about 93 weight percent 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 has average molecular weight in the range of about 1500 to about 15,000, and B. said carboxy-functional compound is a difunctional copolymer of about 5 to about 20 weight percent of an alpha-beta olefinically unsaturated monocarboxylic acid, about 2 to about 10 weight of an alpha-beta olefinically unsaturated amide, and about 70 to about 93 weight percent 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 has average molecular weight in the range of about 1500 to about 15,000, said carboxy-functional compound being present in an amount such that the functional group of greatest concentration thereon provides about 0.3 to about 1.2 functional groups per functional group on said epoxy-functional copolymer that is reactive with said carboxy-functional compound and such that the functional group of second greatest concentration on said carboxy-functional compound provides about 0.1 to about 0.4 functional groups per functional group on said epoxy-functional copolymer that is reactable with said carboxy-functional compound.