Color reduction of polymethylene polyphenyl polyisocyanates

Details Color reduction of polymethylene polyphenyl polyisocyanates Color reduction of polymethylene polyphenyl polyisocyanates

1992-07-23

1994-05-17

Dees, Jose G.

Organic compounds -- part of the class 532-570 series

Organic compounds

Isocyanate esters

560 25, 560331, 560333, 560352, C07C26310, C07C26318

Patent

active

053129717

ABSTRACT:
The present invention is directed to a process for the production of polymethylene polyphenyl polyisocyanates by phosgenating the corresponding polyamines in solution in an inert organic solvent, removing excess phosgene, and stripping the solvent. The improvement resides in adding at least 0.02 parts by weight of reducing agent per 150 parts by weight of polyamine to the polyamines at any time prior to the stripping step.

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patent: 5207942 (1993-05-01), Scherzer et al.

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