Appeal 2006-2775
Application 10/606,399
We AFFIRM.
BACKGROUND
Appellants’ invention relates to a process for preparing polyamines of
the diphenylmethane series. The process comprises reacting aniline and
formaldehyde in the presence of an acid catalyst to form polyamines. The
reaction product is neutralized with a base and phase separated with an
alcohol forming an organic phase comprising polyamines of the
diphenylmethane series and an aqueous phase. In an alternative embodiment
the invention is directed to a process of preparing polyisocyanates of the
diphenylmethane series. This process includes all the process steps
identified above and phosgenating the polyamines from the organic phase
into the corresponding polyisocyanate. Representative claims 1 and 11, as
presented in the Brief, appear below:
1. A process for the preparation of polyamines of the
diphenylmethane series, comprising
a) reacting aniline and formaldehyde in the presence of an acid
catalyst to form polyamines,
b) neutralizing the reaction mixture with a base, and
c) phase separating the neutralized reaction mixture, thereby
forming an organic phase comprising polyamines of the
diphenylmethane series and an aqueous phase,
wherein the quantity of base in step b) exceeds 100% of the
stoichiometrically required quantity for neutralization of the reaction
mixture, and wherein at least one alcohol is added (1) at the beginning
of step b), (2) during step b), or (3) after step b) and before step c),
with the molar ratio of said alcohol to said formaldehyde being at least
0.02:1.
2
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