Thermosetting polyepoxide-polyisocyanate compostions - contg. organic electron acceptor as stabiliser during storage

摘要

Thermosetting resin compsns. contains (A) a polyepoxide and (B) a polyisocyanate in equiv. ratio of >1-40, and opt. (C) a basic hardener to catalyse formation of oxazolidone and isocyanurate and/or uretidione rings, with addn. of (D) a stabiliser to retard polymerisation at 60 degrees C, consisting of an organic electron acceptor with an active methylene or methine gp. or an-electron system. Amt. of (D) is 1x 10-5-5 (1 10-5-1) esp. 1x10-4-1 wt. % based on (A+B). The compsns. are used in the mfr. of heat resistant electronic and electrical components by impregnation, casting or moulding, in combination with glass fabric, mineral fillers, etc. Gelling of the mixts. during storage and processing is retarded even in presence of catalyst, while hardening occurs rapidly on heating.