Patent ID: 6551662
Filing Date: 2003-04-22
Classification: B05D,B29C,B32B,C08K,C08L,C09D,Y10T

Abstract:
A method of coating a metal substrate comprising:(a) heating the metal substrate to a temperature of about 120Â° C. to about 250Â° C. to provide a preheated metal substrate; (b) heating a solid, thermoplastic coating composition to a sufficient temperature to melt the coating composition and provide a molten coating composition, said coating composition comprising: (i) about 50% or more, by total weight of the composition, of a polyester having a weight average molecular weight of about 10,000 to about 50,000, a glass transition temperature of about âˆ’30Â° C. to about 120Â° C., a melt viscosity of about 10 to about 100 Pa.s at 200Â° C. or about 25 to about 200 Pa.s at 240Â° C., a melt flow index of about 20 to about 800 g/10 min at 200Â° C., and a softening point of about 120Â° C. to about 200Â° C., (ii) about 2% to about 25%, by total weight of the composition, of a modifying resin selected from the group consisting of an epoxy or phenoxy resin having an epoxy equivalent weight of about 500 to about 15,000, an acrylic resin having a weight average molecular weight of about 15,000 to about 100,000, and mixtures thereof, and (iii) up to about 25% of a second modifying polymer selected from the group consisting of a carboxylated polyester, a carboxylated polyolefin, a fluorocarbon resin, a styrene resin, an acrylonitrile-butadiene-styrene resin, a chlorinated polyether, a urethane resin, and mixtures thereof; (c) extruding the molten coating composition onto a surface of a preheated metal substrate to provide a layer of molten coating composition about one to about 40 microns thick on the preheated metal substrate and provide a coated metal substrate; and (d) allowing the coated metal substrate to cool.