PROCESS FOR THE PRODUCTION OF POLYISOCYANATES

摘要

A process for the production of a polyisocyanate comprising (a) phosgenating a polyamine to form a polyisocyanate by reacting (1) a polyamine on which the polyisocyanate is based in solution in an inert solvent with (2) phosgene optionally in solution in an inert solvent, (b) separating the solvent from the polyisocyanate, (c) treating the separated solvent to be reused in polyamine solution (1) with an isocyanate trimerisation catalyst.