Polyisocyanate for coatings based on modified 1-isocyanato-3,3,5 trimethyl-5 isocyanatomethyl cyclohexane, process for its preparation and its use in two-component polyurethane powder coatings

摘要

A lacquer polyisocyanate (I) based on modified 1-isocyanato-3, 3-5-trimethyl-5-isocyanato-methylcyclohexane (II) contains (a) 5.7-17 wt.% of trimerised isocyanate gps. in the form of isocyanurate gps., (b) 10.4-29 wt.% of blocked NCO gps., and (c) 2.1-16 wt.% of free NCO gps., all without including the wt. of the blocking agent. The use of (I) in heat-crosslinkable, 2-component polyurethane powder lacquers is claimed. (I) is a stable solid with a low content of by-prods. The optimum melting range can be obtd. by choice of the degree of trimerisation and blocking. The baking temp. of the lacquers is lower than with completely blocked binders. -