Patent ID: 7300997

Claim:
A polyurethane powder coating composition comprising A) at least one epoxy-terminated polyaddition compound having one or more uretdione groups which has a melting point of from 40 to 130° C., a number-average molar mass of between 1,000 and 15,000, and a free isocyanate group content calculated as NCO with a molecular weight=42 of from 0 to 2% by weight; B) at least one hydroxyl-containing polymer having a melting point of from 40 to 130° C. and an OH number of from 20 to 200 mg KOH/g; and C) at least one catalyst selected from the group consisting of a metal acetylacetonate, a metal hydroxide, a metal alkoxide, a quaternary ammonium hydroxide, a quaternary ammonium fluoride, and a quaternary ammonium carboxylate; wherein from 0.3 to 1 uretdione group of component A) are present for each hydroxyl group of component B), and the catalyst C) is present in an amount of from 0.001 to 3% by weight based on the total amount of components A) and B).