Patent · US Expired

Process for producing polyisocyanates of the diphenyl methane series having a reduced color value

US6639102B2 · kind B2 · utility

4Cited by

8References

6Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Torsten Hagen · Essen, DE
Friedhelm Kamper · Krefeld, DE
Daniel Koch · Shanghai, CN
Rudolf Uchdorf · Shanghai, CN
Stefan Wershofen · Mönchengladbach, DE

Key dates

Filing date	Mar 10, 2003
Grant date	Oct 28, 2003
Priority date	—
Expiry date	Mar 10, 2023

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC07C263/10
WIPO fieldOrganic fine chemistry
WIPO sectorChemistry

Abstract

Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.