PROCESS FOR PREPARING FINE-GRAINE, POLYMER COVERED POLYISOCYANATES WITH RETARDED REACTIVITY

摘要

Encapsulated polyisocyanates are prepd. by i) mixing a solid, finely divided polyisocyanate (I) of m. pt. above 38 deg. C with a polyisocyanate (II) of different compsn. in ratio 0.05-50 pts. wt. (II) per 100 pts. wt. (I) at temp. below m. pt. of (I), opt. (II) being dissolved or suspended in an inert, low polar organic solvent, and ii) reacting the coated (I) particles with approx. equiv. amt. of a cpd. (III) reactive to isocyanates to form a polymer capsule from (II) and (III) on the solid core particles of (I). - Finely divided polyisocyanates of retarded reactivity, encapsulated in a different polymer, opt. suspended in a higher mol. polyol and/or higher mol. polyamine, and obtainable by above process through reaction of solid (I) particles, coated by (II), with a (III).