The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 29, 1977
Filed:
Oct. 25, 1974
Hans Joachim Pistor, Walldorf, DT;
Herwig Hoffmann, Frankenthal, DT;
Hans-Ingo Joschek, Mannheim, DT;
Gotthilf Wenner, Ludwigshafen, DT;
Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), DT;
Abstract
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.