Powder paint with epoxy and hydroxy copolymer and anhydride

A thermosettable powder paint which comprises a coreactive mixture of:

• 1. A qualitatively difunctional copolymer having a glass transition temperature in the range of about 40.degree. C. to about 90.degree. C. and a molecular weight (M.sub.n) in the range of about 1,500 to about 15,000, said copolymer being formed from a monomer mixture consisting essentially of
• (a) between about 5 and about 20 weight percent of a glycidyl ester of a monoethylenically unsaturated carboxylic acid;
• (b) between about 2 and about 10 weight percent of difunctional monomers selected from the group consisting of C.sub.5 -C.sub.7 hydroxyalkyl acrylates and C.sub.5 -C.sub.7 hydroxyalkyl methacrylates;
• (c) between about 70 and about 93 weight percent of monoethylenically unsaturated monomers consisting essentially of monofunctional monomers selected from the group consisting of esters of a C.sub.1 -C.sub.8 monohydric alcohol and acrylic acid, esters of a C.sub.1 -C.sub.8 monohydric alcohol and methacrylic acid and C.sub.8 -C.sub.12 monovinyl hydrocarbons;
• and
• (d) up to 30 weight percent of modifying monomers selected from the group consisting of vinyl chloride, acrylonitrile, methacrylonitrile and vinyl acetate;
• and
• 2. Crosslinking agent consisting essentially of anhydrides selected from the group consisting of
• (a) monomeric anhydrides of dicarboxylic acids, and
• (b) homopolymers of anhydrides of dicarboxylic acids,
• said anhydrides being present in an amount that provides between about 0.3 and about 1.2 anhydride groups for each functional group on said copolymer.

A thermosettable powder paint which, exclusive of pigments, catalysts, antistatic agents, plastizers, flow control agents and other nonreactive additives, consists essentially of a coreactive particulate mixture of:

• 1. A qualitatively difunctional copolymer having a glass transition temperature in the range of about 50.degree. C. to about 80.degree. C. and a molecular weight (M.sub.n) in the range of about 2,500 to about 6,000, said copolymer being formed from a monomer mixture consisting essentially of
• (a) between about 8 and about 15 weight percent of a glycidyl ester of a monoethylenically unsaturated carboxylic acid;
• (b) between about 2 and about 10 weight percent of difunctional monomers selected from the group consisting of C.sub.5 -C.sub.7 hydroxyalkyl acrylates and C.sub.5 -C.sub.7 hydroxyalkyl methacrylates;
• and
• (c) between about 75 and about 90 weight percent of monoethylenically unsaturated monomers consisting essentially of monofunctional monomers selected from the group consisting of (i) esters of a C.sub.1 -C.sub.8 monohydric alcohol and acrylic acid, (ii) esters of a C.sub.1 -C.sub.8 monohydric alcohol and methacrylic acid, and (iii) C.sub.8 -C.sub.12 monovinyl hydrocarbons, the total of said monofunctional monomers (i) and (ii) comprising at least 50 weight percent of said monofunctional monoethylenically unsaturated monomers of said monomer mixture;
• and
• 2. Crosslinking agent consisting essentially of anhydrides selected from the group consisting of
• (a) monomeric anhydrides of dicarboxylic acids, which anhydrides have melting points in the range of about 35.degree. C. to about 140.degree. C., and
• (b) homopolymers of anhydrides of dicarboxylic acids, said homopolymers having a molecular weight (M.sub.n) in the range of about 1,000 to about 2,500,
• said anhydrides being present in an amount that provides between about 0.3 and about 1.2 anhydride groups for each functional group on said copolymer.