Patent ID: 7888431

Claim:
A coating composition, containing a film forming binder and a volatile organic liquid carrier for the binder, wherein the binder contains (A) a hydroxyl polymer component comprising at least one hydroxyl-containing acrylic polymer; (B) at least one hydroxyl-terminated component selected from the group consisting of (1) an organic diol having the formula where R 1 and R 2 are individually selected from the group consisting of hydrogen and an alkyl group having 1, 3-5 carbon atoms and (2) a hydroxyl terminated reaction product of trimethylol propane and a lactone; and (C) an organic polyisocyanate component, at least a portion of which comprises a trimer selected from the group consisting of a trimer of isophorone diisocyanate and a trimer of hexamethylene diisocyanate and any mixtures thereof, wherein the organic polyisocyanate component further comprises at least one of an asymmetric hexamethylene diisocyanate trimer, a biuret of hexamethylene diisocyanate, a biuret of isophorone diisocyanate and any mixtures thereof; wherein the ratio of equivalents of isocyanate per equivalent of hydroxyl groups in the binder is in the range of about 0.7/1 to 2.0/1; and wherein the composition further contains (D) a catalyst system for the binder comprising (i) at least one organotin compound, (ii) at least one tertiary amine, (iii) at least one organic carboxylic acid; and (iv) optionally, at least one organic acid salt selected from the group consisting of zinc organic acid salts and calcium organic salts; wherein the coating composition cures at ambient temperatures to a water spot free state within 2 hours after application wherein the hydroxyl-containing acrylic polymer comprises 5 to 50% by weight, based on the weight of the acrylic polymer, of a hydroxyl acrylic polymer having a weight average molecular weight of above 10,000 to 20,000, 20-60% by weight, based on the weight of the acrylic polymer, of a hydroxyl acrylic polymer having a weight average molecular weight of above 7,000 and up to 10,000 and 20-70% by weight by weight, based on the weight of the acrylic polymer, of a hydroxyl acrylic polymer having a weight average molecular weight of 2,000 up to 7,000.