VERFAHREN ZUR HERSTELLUNG VON MISCHUNGEN AUS DIPHENYLMETHANDIISOCYANATEN UND POLYPHENYL- POLYMETHYLEN-POLYISOCYANATEN MIT EINER VERMINDERTEN IODFARBZAHL UND EINEM REDUZIERTEN CHLORGEHALT

摘要

Prodn. of mixts. of diphenylmethanedi-isocyanates and polyphenyl-polymethylene-polyisocyanates (i.e. crude MDI) with a low iodine number and a low chlorine content comprises (a) reacting the corresp. mixts. of diamines and polyamines (MDA) with phosgene in presence of inert solvent(s) at elevated temp., (b) removing excess phosgene and solvent and (c) thermal treatment of the prod.. After phosgenation (a), an effective amt. of a mixt. (I) of water and mono- or polyhydric polyoxyalkylene alcohol(s) (II) is added to the reaction mixt. in the presence or absence of phosgene.