Patent · US Expired

Process for the production of polyisocyanates of the diphenylmethane series with a reduced color value

US6720455B2 · kind B2 · utility

3Cited by

4References

6Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Torsten Hagen · Essen, DE
Friedhelm Kamper · Krefeld, DE
Daniel Koch · Shanghai, CN
Heinz Muller · Krefeld, DE

Key dates

Filing date	Aug 20, 2002
Grant date	Apr 13, 2004
Priority date	—
Expiry date	Aug 27, 2022

Classification

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

Abstract

Polyisocyanates of the diphenylmethane series are produced by a) reacting aniline and formaldehyde in the presence of an acidic catalyst to produce a polyamine, b) neutralizing the reaction mixture from step a) with a base at a temperature of more than 110° C. or neutralizing the reaction mixture from step a) with a base and heating the neutralized mixture to a temperature of more than 110° C., and c) phosgenating the polyamine from step b) to convert it to the corresponding polyisocyanate.

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