Polyaddition products containing hydroxy- and uretdione groups, process for their preparation and their use for the preparation of polyurethane-powder lacquers having high reactivity and not releasing any decomposition product and polyurethane-powder lacquers prepared by this process

摘要

Hydroxyl and uretdione gp-contg. polyaddn. prods. (I) with terminal OH gps., a functionality of 2 and mol. wts. of 4500-10000 pref. 4500-7000 are obtd. by reaction of: (i) 40-85 wt.% of the uretdione of IPDI; and (ii) 60-15 wt.% diols and/or chain-extenders. Also claimed is a process for the prodn. of (I) by reacting (i) and (ii) in solvent at 50-100 degrees C and then removing the solvent, or without solvent in an intensive kneader, pref. a twin screw extruder at 120-190 degrees C opt. in the presence of 0.01-1 wt.% catalyst. Also claimed are cleavage-free, transparent or pigmented polyurethane (PU) coating powders (II) contg. unblocked polyaddn. prods. (I) in combination with OH gp.-contg. polymers (III) and additives etc., substrates with heat-cured coatings of (II) are also claimed.