Patent ID: 7531614

Claim:
A coating composition consisting of: a water-thinnable polyurethane with at least two free OH groups obtained from the reactions consisting of: a first conversion of a primary and/or secondary alkanolamine with a NCO compound giving an intermediate product, followed by the addition of a cyclic carboxylic anhydride to the intermediate product; wherein the NCO compound has at least one free NCO group and no blocked NCO group, and the NCO compound is obtained by reacting at least one polyol with at least one polyisocyanate, in which the polyol is saturated polyester polyol or saturated polyether polyol; all alkanolamine being converted during the first conversion to the intermediate product such that the nitrogen atom of the alkanolamine reacts with one of the free NCO groups of the NCO compound to form a urea bond; and the cyclic carboxylic anhydride reacting, with ring opening, with the OH group, originating from the alkanolamine, of the intermediate product and wherein the coating composition further consists of a crosslinking agent that is reactive with the water-thinnable polyurethane, the crosslinking agent consisting of a melamine resin wherein the melamine resin is one without NH groups.