Production of blocked, urethanised polyisocyanate for use in coating powder involves reacting chlorine-free isophorone di-isocyanate with polyol and blocking agent other than epsilon-caprolactam

摘要

Isophorone di-isocyanate (IPDI) with a chlorine content of less than 10 ppm and blocking agents other than epsilon-caprolactam are used in a method for the production of blocked, urethane group-containing polyisocyanates by reacting IPDI with polyol(s) and blocking agent. A method for the production of blocked, urethane group-containing polyisocyanates (I) based on isophorone di-isocyanate (IPDI) involves reacting (i) 2-8 NCO-equivalents of IPDI containing less than 10 ppm chlorine with (ii) 1 OH-equiv. polyol(s) and (iii) blocking agent(s) other than epsilon-caprolactam in amounts of 0.7-1.1 mol per NCO-equiv. urethanised IPDI. Independent claims are also included for: (a) blocked polyisocyanates derived from the above components; and (b) transparent or pigmented polyurethane coating powders containing (I) plus polymers with functional groups and other additives etc. as required.