Ductile coating composition of an acrylic polymer having reactive sites and an epoxy resin

Claim 1

A coating composition consisting essentially of a compatible mixture of film-forming constituents in a liquid carrier; wherein the film-forming constituents consist essentially of a. 60-95% by weight of an acrylic polymer of hard and soft segments and having a number average molecular weight of about 25,000-70,000 determined according to gel permeation chromatography and a glass transition temperature of about -20° C. to +60° C. and wherein the acrylic polymer consists essentially of polymerized units of about 10-50% by weight of styrene, methyl styrene, methyl methacrylate or acrylonitrile, 40-89.5% by weight of an alkyl acrylate having 1-18 carbon atoms in the alkyl group or an alkyl methacrylate having 2-18 carbon atoms in the alkyl group, 0.5-10% by weight of an unsaturated carboxylic acid; and b. 5-40% by weight of an epoxy resin having at least one vic epoxy group in combination with at least one hydroxyl group or epoxide group or mixture thereof per polymer chain and having a number average molecular weight of 300 to 20,000 determined as above; wherein the film-forming constituents in the fully cured state have a brittle ductile transition temperature of about -40° C. to +20° C. measured at an elongation rate of 10% per minute on an Instron testing machine using a free film about 2.0-4.0 mils thick of the fully cured composition.