Appeal No. 2001-2554 2
Application No. 08/925,321
THE INVENTION
The invention is directed to a method of treating cellulose pulp containing
hexenuronic acid, wherein the amount of hexenuronic acid present therein is reduced by at
least 50%. The process includes treating cellulosic pulp obtained by alkaline delignification
at an acid pH and a temperature such that the reduction in hexenuronic acid is
accomplished and the Kappa number is reduced by at least two units. Additional
limitations are described in the following illustrative claim.
THE CLAIM
Claim 1 is illustrative of appellants’ invention and is reproduced below.
1. A method of treating chemical cellulose pulp produced by alkaline delignification
and having a kappa number of under 24, having hexenuronic acid therein, comprising the
steps of:
(a) treating chemical cellulose pulp produced by alkaline delignification having a
kappa number under 24 and at a solids consistency of between 0.1-50% by treating the
pulp at a temperature over 85/C and at a pH between about 2-5 for sufficient time to
remove at least 50% of the hexenuronic acid and to reduce the kappa number by at least
2 units; and
(b) bleaching the chemical cellulose pulp produced by alkaline delignification having
a kappa number under 24 in at least one bleaching stage.
THE REFERENCES OF RECORD
As evidence of obviousness, the examiner relies upon the following references:
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