Process for the preparation of polymeric methylendiphenylene diisocyanate having reduced color and chloride content.

摘要

Addition of minor quantities of carboxylic acids downstream from the last phosgene reactor in polymethylene polyphenylene polyisocyanate production, and preferably to the phosgene stripper, results in the production of polymethylene polyphenylene polyisocyanates having reduced color and/or hydrolyzable chlorides.