Self crosslinking powder coating compositions ii

Claim 2

A powder coating composition comprising a mixture of: (A) a copolymer formed from (a) stoichiometric ratio of 0.4 to 1.6 of a monomer containing hydroxy functional groups selected from the group consisting of 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate and hydroxypropyl acrylate and a monomer containing carboxy functional groups selected from the group consisting of methacrylic acid and acrylic acid, said copolymer also containing (b) modifying vinyl monomers having no functional groups and so selected that said copolymer has a glass transition temperature of from about 40* to about 90*C and a molecular weight (Mn) in the range from about 2,000 to about 15, 000; (B) a flow control agent forming from about 0.05% to about 4.0% by weight of the mixture, said flow control agent being a polymer having a molecular weight (Mn) of at least 1,000, and having a glass transition temperature of at least 50*C below the glass transition temperature of said copolymer, said flow control Agent further being a polymer or copolymer selected from the group consisting of acrylate esters, methacrylate esters and polyethylene or polypropylene glycol esters of fluorinated fatty acids; and (C) a small weight percent of a catalyst which produces a gel time for the powder coating composition greater than one minute at the baking temperature of the composition.

Claim 3

The powder coating composition defined in claim 3 wherein: said monomer containing hydroxy functional groups is present in said copolymer from about 8% by weight to about 25% by weight, and wherein: said monomer containing said carboxy functional groups is present in said copolymer in the range from about 5% by weight to about 20% by weight.

Claim 4

The powder coating composition of claim 3 wherein: said modifying monomers are selected from the group consisting of methyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha methyl styrene, acrylonitrile, and methacrylonitrile.

Claim 5

The powder coating composition of claim 3 wherein: said acrylate ester is selected from the group consisting of polylauryl acrylate, polybutyl acrylate and poly (2-ethyl-hexyl acrylate).

Claim 6

The powder coating composition of claim 3 wherein: a pigment is included which forms from about 2% by weight to about 35% by weight of the total mixture, wherein: a small weight percentage of an antistatic agent is included, and wherein a plasticizer is included from about 2% by weight to about 10% by weight of the total mixture.