Coating composition for flexible substrates

Claim 1

A coating composition comprising 5-60% by weight of a film-forming binder and 40-95% by weight of an organic solvent for the binder; wherein the binder consists essentially of about A. 20-90% by weight of an acrylic polymer containing hydroxyl groups selected from the group of an acrylic polymer consisting essentially of 20-40% by weight of methyl methacrylate, 40-74% by weight of an alkyl methacrylate having 2-12 carbon atoms in the alkyl group or an alkyl acrylate having 1-12 carbon atoms in the alkyl group, 5-15% by weight of a hydroxy alkyl methacrylate or a hydroxy alkyl acrylate each having 2-4 carbon atoms in the alkyl group and 1-5% by weight of an alkyl amino alkyl methacrylate or an alkyl amino alkyl acrylate and an acrylic polymer consists essentially of 20-44% by weight of methyl methacrylate, 50-70% by weight of an alkyl methacrylate having 6-12 carbon atoms in the alkyl group or an alkyl acrylate having 2-12 carbon atoms in the alkyl group, 5-20% by weight of a hydroxy alkyl acrylate or a hydroxy alkyl methacrylate or a mixture thereof of each having 2-4 carbon atoms in the alkyl group and 1-20% by weight of an α,β ethylenically unsaturated carboxylic acid; wherein the acrylic polymer has a weight average molecular weight of about 5,000-80,000 determined by gel permeation chromatography; B. 5-40% by weight of a hydroxy terminated ester of a bis primary diol of 2-22 carbon atoms and a hydroxy terminated mono carboxylic acid or a hydroxy terminated polyester of the esterification product of neopentyl glycol and mixed methyl esters of succinic acid, glutaric acid and adipic acid; and C. 5-75% by weight of an organic aliphatic or cycloaliphatic polyisocyanate; wherein a dried film of about 2 mils thick of the composition on a flexible hydrocarbon rubber substrate can withstand a 360° mandrel bend test at 5° C. without cracking of the film or loss of adhesion of the film to the substrate.