Isocyanate prepolymer mixt. for high strength polyurethane foam

摘要

An NCO-prepolymer mixt. (I) contg. urethane gps. and 2.5-30 wt.% reactive NCO gps. is obtd. by reacting: (a) 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate, an isomer mixt. of 4,4'- and 2,4'- and opt. 2,2'-diphenylmethane diisocyanate or a mixt. of diphenylmethane diisocyanates and polyphenyl-polyphenylene polyisocyanates; and(b) a soln. contg.: (b-i) polyoxyethylene glycol(s) (PEG) with a mol.wt. of 400-4000; and (b-ii) lignin. Also claimed are:(A) a method for producing (I) by reacting the specified organic polyisocyanates and soln.; and (B) a method for producing compact or cellular polyurethanes, pref. polyurethane foam.