Appeal 2006-2775
Application 10/606,399
11. A process for the preparation of polyisocyanates 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,
c) phase separating the neutralized reaction mixture, thereby
forming an organic phase comprising polyamines of the
diphenylmethane series and an aqueous phase,
and
d) phosgenating the resultant polyamines into the corresponding
polyisocyanates,
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.
CITATION OF REFERENCE
The Examiner relies on the following reference in rejecting the
appealed claims:
Adkins 5,312,971 May 17, 1994
Claims 1, 9 to 11, 19, and 20 stand rejected under 35 U.S.C. § 103(a)
as obvious over Adkins (Answer 3-5).
OPINION2
The Examiner found that Atkins teaches a process for preparing
polyisocyanates that renders obvious the subject matter of the independent
2 We select independent claims 1 and 11as representative of the appealed
claims. We will also address the separately argued claims 10 and 20.
3
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