| 摘要 |
<p>Quaternary ammonium salts with hydroxide or fluoride as counterion accelerate the back cleavage of the uretdione groups so strongly that, in the use of known uretdione powder paints, the curing temperature of the powder paint composition can be considerably lowered. Polyurethane powder paint compositions contain: (A) at least one uretdione-containing powder paint hardener based on aliphatic or cycloaliphatic polyisocyanates and hydroxy (OH) group-containing compounds of m. pt. 40-130degreesC, a free isocyanate (NCO) content of less than 5 wt.%, and a uretdione content of 6-18 wt.%; (B) at least one OH group-containing polymer of m. pt. 40-130degreesC and OH number 20-200 mg KOH/g; and (C) at least one quaternary ammonium catalyst of formula (I). +NR1R2R3R4 -R5 (I) R1-R4 = 1-18C alkyl, aryl, aralkyl, heteroaryl, alkoxyalkyl, unbridged or bridged with other R1-R4 residues, with formation of single, double or triple rings, where the bridging atom can be carbon or a heteroatom, and each R1-R4 residue can have in addition one or more alcohol, amine, ester, keto, thio, urethane, urea, allophanate, double bond, triple bond, or halogen atom; and R5 = OH or F. (A) and (B) are in such a ratio that for each OH group of component (B) there are 0.3-1 uretdione groups of component (A), and the amount of catalyst (C) is 0.001-3 wt.% on the total amounts of (A) and (B). Independent claims are also included for the following: (1) a process for preparation of the uretdione powder paint hardener containing components (A), (B) and the catalyst (C) in heatable aggregates at 120-130degreesC; (2) a catalyst for accelerating curing of the powder paint composition containing a compound of formula (I).</p> |
