Appeal No. 1996-2350
Application 07/843,833
BACKGROUND
Appellant's invention relates to a method of
treating unbleached pulp derived from a Kraft digestion
process. In an initial chlorine free bleaching stage, the
pulp is contacted with a pressurized mixture of ozone and
oxygen in a mixer at pH and temperature conditions that allow
for the ozone to react with components of the pulp but not the
oxygen. After essentially all of the ozone is consumed by
reaction with pulp components, the pH and temperature are
altered so that the oxygen from the initially supplied mixture
of ozone and oxygen reacts with the pulp components.
Subsequent to a following water washing step, the washed and
so treated pulp is subjected to another round of contacting
with an ozone and oxygen mixture and the reaction steps as set
forth above. Exemplary claim 1, the sole independent claim on
appeal, is reproduced below.
1. In the treatment of kraft pulp comprising wood
fibers to render the pulp useful in end use applications
requiring a pulp viscosity of at least about 10 cP and a P.
No. of at least about 9 and wherein said pulp has been
digested employing a kraft process, the improvement comprising
a two-phase post-digestion treatment, including contacting, in
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