PREPARATION OF POLYMETHYLENE POLYPHENYL POLYISOCYANATE

摘要

Disclosed herein is an improved process for the preparation of polymethylene polyphenyl polyisocyanate by reacting phosgene with a corresponding polyamine, followed by removing residual phosgene from the reaction mixture, the improvement comprising removing the residual phosgene by contacting the reaction mixture which is maintained at 150 degrees Centigrade or lower, with an inert solvent vapor stream at a temperature which is sufficient to effect a substantially complete removal of the residual phosgene.