GB1402606A - Acrylic powders - Google Patents

Abstract

1402606 Acrylic polymer powders PPG INDUSTRIES Inc 7 July 1972 [9 July 1971] 31911/72 Heading C3P A polymer of an acrylic or methacrylic monomer or copolymer of such monomers in powder form which has a softening point of at least 50‹ C. and which forms a continuous film when applied to a substrate and heated is produced by (a) polymerizing one or more ethylenically unsaturated acrylic or methacrylic monomers in an organic dispersion liquid which is a solvent for the monomers but a non solvent for the polymer formed therefrom in the presence of a free radical catalyst and a dispersion stabilizer which is the polymeric reaction product of a polymer of a hydroxy fatty acid, glycidyl acrylate or methacrylate, an acrylic or methacrylic ester (other than the glycidyl ester) and an ethylenically unsaturated carboxylic acid to form a polymer dispersion (b) adding a pigment paste to the dispersion and (c) drying the mixtue of pigment and polymer to produce an acrylic polymer powder. The dispersion stabilizer may be formed by graft polymerizing the reaction product of glycidyl methacrylate and poly-(12 hydroxystearic acid) with methyl methacrylate and additional glycidyl methacrylate followed by reaction of the resulting product with methacrylic acid. The product polymer may be thermoplastic or thermosetting. In the examples to a mixture of hexane, heptane, methylmethacrylate, azobisisobutyronitrile and as dispersion stabilizer the reaction product of methylmethacrylate, glycidyl methacrylate, methacrylic acid and poly- (12 hydroxystearic acid) in solution in ethylacetate, butylacetate and naphtha heated to reflux is added further of the dispersion stabilizer and the initiator; methyl methacrylate plus one or more of 2 ethyl hexyl (or butyl or glycidyl)methacrylate,hydroxyethyl (or propyl)- methacrylate, N-butoxymethacrylamide and methacrylic acid, and one or more of a solution of coconut oil in xylene, glyceryl tribenzoate, methylene bis-(cyclohexyl isocyanate) blocked with methyl ethyl ketoxime, n-octyl mercaptan and hexamethoxymethylmelamine and the resulting dispersion is spray dried to form a powder which is applied to steel or other substrates electrostatically and baked.