Patent ID: 7572876

Claim:
A highly reactive polyurethane powder coating composition, comprising: A) at least one uretdione powder coating hardener, based on aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates and compounds containing hydroxyl groups, said hardener having a melting point of 40 to 130° C., a free NCO content of less than 5% by weight and a uretdione content of 6-18% by weight, B) at least one polymer containing a hydroxyl group with a melting point of 40 to 130° C. and an OH value between 20 and 200 mg KOH/g, C) 0.001-3% by weight, based on a total weight of components A) and B), of at least one catalyst having the formula [NR 1 R 2 R 3 R 4 ] + [R 5 COO] − , wherein R 1 -R 4 simultaneously or independent of each other are alkyl, aryl, aralkyl, heteroaryl, alkoxyalkyl radicals, optionally linear or branched, unbridged or bridged with other R 1 -R 4 radicals, with the formation of cycles, bicycles or tricycles and wherein the bridging atoms, in addition to carbon, are optionally heteroatoms, with 1-18 carbon atoms and wherein every R 1 -R 4 radical also has at least one group selected from the group consisting of alcohol, amino, ester, keto, thio, urethane, urea, allophanate groups, double bonds, triple bonds, and halogen atoms, and R 5 is an alkyl, aryl, aralkyl, heteroalkyl, alkoxyalkyl radical, linear or branched with 1-18 carbon atoms and optionally having one or more alcohol, amino, ester, keto, thio, urethane, urea, allophanate groups, double bonds, triple bonds or halogen atoms; wherein components A) and B) are in such a ratio so that there is 0.3 to 1 uretdione group of component A) for each hydroxyl group of component B).