Solid Polyurethane Powder Coating Compositions Containing Uretdione Groups that are Hardenable at Low Tempratures

摘要

Highly reactive polyurethane powder lacquer composition contains (A) powder lacquer hardener(s) containing under 5 wt.% free isocyanate and 6-18 wt.% uretdione and based on (cyclo)aliphatic polyisocyanates and compounds with hydroxyl (OH) groups, (B) polymer(s) with OH groups and OH number 20-200 mg KOH/g, both melting at 40-130[deg]C, to give 0.3-1 uretdione groups/OH, and (C) 0.001-3 wt.% quaternary ammonium carboxylate as catalyst. Highly reactive polyurethane powder lacquer composition contains (A) powder lacquer hardener(s) based on (cyclo)aliphatic polyisocyanates and compounds containing hydroxyl (OH) groups, which have a melting point (m.pt.) of 40-130[deg]C and contain less than 5 wt.% free isocyanate and 6-18 wt.% uretdione, (B) polymer(s) containing OH groups with a m.pt. of 40-130[deg]C and OH number of 20-200 mg KOH/g and (C) catalyst(s) comprising quaternary ammonium carboxylate(s) of formula (I), in ratios giving 0.3-1 uretdione groups in (A)/OH in (B) and 0.001-3 wt.% (C) with respect to (A) + (B): [NR 1>R 2>R 3>R 4>] +> [R 5>COO] -> (I); R 1> -> 4>optionally bridged organyl; R 5>organyl . The full definitions are given in the DEFINITIONS (Full Definitions) Field. Independent claims are also included for the following: (1) production of highly reactive polyurethane powder lacquer compositions containing (A), (B) and (C) as above and optionally (D) 0.1-10 wt.% compound(s) reactive towards acid groups, in heatable aggregates with an upper temperature limit of 120-130[deg]C; (2) catalysts (I) for accelerating the cure of powder lacquer compositions based on a powder lacquer hardener containing uretdione and a polymer containing OH groups.