Appeal No. 2005-1096
Application 08/894,156
BACKGROUND
The invention relates to a process for the preparation of a polyisocyanate
which contains one or more biuret groups by reacting a) an aliphatic or cycloaliphatic
isocyanate containing two or more isocyanate groups (isocyanate a) with b) a
tertiary alcohol or a mixture of water and a tertiary alcohol (biuretizing agent b) at
from 100 to 250°C. The reaction is carried out in the presence of a stabilizer
consisting essentially of a catalytic amount of urea, ammonia, biuret, a urea
derivative of a specified formula I, or a carboxamide of a specified formula II.
(Appeal Brief, pages 2-3). Claim 1, which is illustrative of the subject matter on
appeal, reads as follows:
1. A process for the preparation of a polyisocyanate which contains
one or more biuret groups by reacting
a) an aliphatic or cycloaliphatic isocyanate containing two or more
isocyanate groups (isocyanate (a)) with
b) 0.5 to 20 mol% based on the isocyanate groups in (a) of a tertiary
alcohol or a mixture of water and a tertiary alcohol (biuretizing agent (b))
at from 100 to 250°C, which comprises carrying out the reaction in the
presence
c) from 0.01 to 2.0 mol% based on the isocyanate groups in (a) of a
stabilizer (c) selected from the group consisting of urea, ammonia,
biuret, ethylene urea, a urea derivative of the formula I
O
R1 R3
R2 N C N
R 4 (I)
in which R1, R2, R3 , and R4 are hydrogen, C1 to C10 alkyl or C6 to C10
aryl, or a carboxamide of the formula II
O
H
5 1
R C N R
(II)
2
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