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:
May. 04, 1993
Filed:
Feb. 08, 1991
Dietrich Scherzer, Ludwigshafen, DE;
Roland Minges, Gruenstadt, DE;
Werner Langer, Ludwigshafen, DE;
Bernd Bruchmann, Ludwigshafen, DE;
Wolfgang Heider, Limburgerhof, DE;
Peter Keller, Hirschberg, DE;
Arnold Schmitt, Friedelsheim, DE;
Willy Van Pee, Kapellen, DE;
BASF Aktiengesellschaft, , DE;
Abstract
Mixtures of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates (crude MDI) having a reduced iodine color number are prepared by reacting the corresponding mixtures of diphenylmethanediamines and polyphenylpolymethylene-polyamines with phosgene in the presence of one or more inert organic solvents at elevated temperatures by a process in which low molecular weight alkanols, polyhydric alcohols, preferably dihydric to octahydric alcohols having a molecular weight of from 60 to 350, or mixtures thereof are incorporated in an effective amount, advantageously in an amount of from 0.01 to 5% by weight, based on the weight of crude MDI, into the reaction mixture after the end of the phosgenation, the phosgene and the inert organic solvent are then separated off, from 0 to 5% by weight, based on the weight of crude MDI, of one or more phenol-based antioxidants and/or aryl phosphite are added to the reaction product, and the reaction mixture is subjected to a thermal treatment.