Basf Aktiengesellschaft

Hans J Astheimer

Friedrich Sauer

Rainer Ohlinger

Willy Van Pee

Rudolf Schmidt

Horst Brandtstaedter

Jaak Van Steen

Siegfried Krueger

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.

Process for the manufacture of 4,4'-diphenyl-methane diisocyanate and a

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Neuhofen, Germany

Hans J Astheimer