Di:isocyanate-free poly:isocyanate prepn. - by trimerisation of di:isocyanate with heat-decomposable catalyst, and sepn. by distn.

摘要

Polyisocyanates (I) with isocyanurate structure, contg. is not 50 wt.% tris-isocyanatomonoisocyanurates and is not >3 wt.% diisocyanates (II) free from isocyanurate gps., are prepd. by (a) trimerisation of (II) to 5-40% conversion of the isocyanate gps., (b) addn. of a catalyst poison to stop the reaction, and (c) removal of uncoverted (II) by distn. in presence of 1-30 wt.% w.r.t. the prod. remaining as distn. residue, of an inert, liq. distn. aid with b.pt. is not 50 degrees C higher than that of (II). The catalyst is deactivated without addn. of a catalyst poison, esp. by thermal deactivation. (I) are used in 2-component polyurethane lacquers, and in natural or synthetic rubber adhesives.