VERFAHREN ZUR HERSTELLUNG VON MISCHUNGEN AUS DIPHENYL-METHAN-DIISOCYANAT-ISOMEREN MIT EINEM GERINGEN GEHALT AN URETDIONEN UND HYDROLYSIERBAREN CHLORVERBINDUNGEN.

摘要

A process for the manufacture of 4,4'-diphenylmethane diisocyanate and a mixture of diphenylmethane diisocyanate isomers containing a controllable amount of uretdione and hydrolizable chlorine which comprises feeding crude MDI to an evaporator, condensing a head fraction in two stages in the presence of an inert gas, feeding the first stage condensate to a distillation column, producing a mixture of diphenylmethane diisocyanate isomers as an overhead, producing 4,4'-diphenylmethane diisocyanate as a side draw, and condensing each of the overhead and side draw in two stages in the presence of an inert gas.