INTEGRATED PROCESS FOR THE PREPARATION OF METHYLENE DIPHENYLENE DIISOCYANATES AND POLYMETHYLENE POLYPHENYLENE POLY (ISOCYANATES) FROM DIAMINES AND POLYAMINES

摘要

A process is presented for a multi-step process for the preparation of methylene diphenylene diisocyanates (MDI) or polymethylene polyphenylene poly (isocyanates) (PMDI) from methylene diphenylene diamines or polymethylene polyphenylene polyamines and isocyanic acid to form ureas which are reacted with dialkyl amines to give a corresponding dialkyl urea or poly (alkyl urea) product which are then thermally reacted in the presence of various reaction promoters to give the corresponding isocyanate MDI or PMDI product.