Process for polymeric MDA, recycle of finished polymeric MDA

Details Process for polymeric MDA, recycle of finished polymeric MDA Process for polymeric MDA, recycle of finished polymeric MDA

1987-02-26

1988-12-20

Hines, Robert V.

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

Organic compounds

Amino nitrogen containing

564331, 564335, C07C 8524

Patent

active

047926244

ABSTRACT:
'An improvement is described in the process of preparing polymethylene polyphenyl polyamines by condensing aniline and formaldehyde in the presence of an acid catalyst. The improvement entails adding a minor proportion of a polyamine mixture comprising di(aminophenyl)methanes and oligomeric polymethylene polyphenyl polyamines, collectively known as polymethylene polyphenyl polyamines or polymeric MDA, to an intermediate stage of the condensation reaction where the various intermediately formed aminobenzylamines are present. The process lends itself to either a batch or continuous method for preparing the polyamines.
The improvement is actually observed in the polymethylene polyphenyl polyisocyanates derived from the polyamines which have substantially reduced color over those polyisocyanates prepared from polyamines prepared via a prior art method. Such color improvements invariably carry over to polyurethane products derived therefrom.

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