To obtain a polyurethane powder coating composition curable at a low baking temperature and to coat a heat-resistant substrate with the composition.
This polyurethane powder coating composition comprises (A) a binder component which is solid at <40°C, is liquid at ≥130°C and has 25-200 OH value and 400-10,000 number-average molecular weight, (B) a polyaddition compound which is solid at <40°C, is liquid at ≥125°C, contains a uretedione group and optionally a free isocyanate and is prepared from an aliphatic and/or alicyclic diisocyanate and (C) one or more catalysts containing an N,N,N'- trisubstituted amidine group and having 12.0-47.0wt.% amidine group content [calculated as CN2 (molecular weight: 40)]. The components A and B exist in amounts to give 0.6-1.4 isocyanate groups of the component B based on each hydroxyl group existing in the component A and the amount of the component C is 0.05-5wt.% based on the total weight of the coating composition.
MEIER-WESTHUES HANS-ULRICH DR
HALPAAP REINHARD DR
FREUDENBERG ULRICH DR
KLEE HANS-PETER
