Badische Anilin- & Soda-fabrik Aktiengesellschaft

Hans Joachim Pistor

Herwig Hoffmann

Hans-Ingo Joschek

Gotthilf Wenner

Production of 4,4'-diphenylmethane diisocyanate and a mixture of diisocyanates and polyisocyanates by the phosgenation of pure 4,4'-diaminodiphenylmethane and a mixture of diamines and polyamines. 4,4'-Diaminodiphenylmethane is obtained by distillation of the mixture of products obtained from the reaction of aniline with formaldehyde and crystallization of the distillate from a solvent. The combined distillation residue and mother liquor from the crystallization form the mixture for reaction with phosgene to produce a mixture of diisocyanates and polyiisocyanates. This process produces a highly pure 4,4'-diphenylmethane diisocyanate which is particularly suitable for the production of polyurethanes serving as intermediates in the manufacture of rigid foams or as glue.

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Walldorf, Germany

Hans Joachim Pistor