Coating composition of a hydroxy functional epoxy ester resin and polycaprolactone diol

An organic solvent based, thermosetting coating composition comprising:

• (A) hydroxy functional epoxy ester resin having a number average molecular weight (M.sub.n) of between about 1,000 and about 4,000, and being the reaction product of (1) a chain extended product of (i) diepoxide selected from the group consisting of bisphenol-A epichlorohydrin epoxy resin, hydantoin epoxy resin, cyclic and acyclic aliphatic diepoxide and mixtures thereof, (ii) diphenol selected from the group consisting essentially of bisphenol-A, bisphenol-B, and bisphenol-F and mixture thereof (iii) dicarboxylic acid consisting essentially of the dimerization product of C-18 fatty acid and (2) acid component in chain termination reaction comprising hydroxy functional acid and a fatty acid and reacted in about a 1-to-1 equivalent ratio to chain extended product, said acid component selected from the group consisting of dimethylolpropionic acid, bis(hydroxy ethyl)propionic acid, bis(hydroxy propyl)propionic acid, and mixtures thereof and said fatty acid selected from the group consisting of soya fatty acid, butyric, lauric, palmitic and stearic fatty acids and mixtures thereof, said diepoxide being reacted substantially simultaneously with said diphenol and dicarboxylic acid in amounts sufficient to give a weight per epoxide between about 500 and about 2,500;
• (B) linear polycaprolactone diol having a molecular weight between about 1500 and about 5000 and made by polymerizing epsilon-caprolactone monomer in the presence of compounds having two functional groups each having an active hydrogen capable of opening the lactone ring and at a temperature between about 50.degree. C. and about 300.degree. C., wherein said (A) and (B) are included in said composition in a weight ratio between about 4:1 and 1:4;
• and
• (C) blocked polyisocyanate crosslinking agent comprising at least two isocyanate groups which have been blocked by reaction with an active hydrogen bearing blocking agent, which un-blocks at the cure temperature of said composition, said blocked polyisocyanate being selected from blocked aliphatic, aromatic, cycloalkylene, aliphatic aromatic and nuclear substituted aromatic polyisocyanates, said crosslinking agent being included in said composition in an amount equal to between about 10 and 50 percent of the combined weight of said (A) and (B) in said composition.