Appeal No. 1998-2077
Application 08/553,324
would have recognized that the use of any ozone step in a bleaching process is an acidic step. See, e.g.,
Backlund, col. 3, lines 55-56.
I find that one of ordinary skill in this art would have found in or inferred from the combined
teachings of the applied references, as discussed above, the affect of each of the Q, P and Z stages,
separately and alternatively positioned in sequences, and any intervening washing steps, on oxygen
delignified pulp at different points in bleaching sequence. Indeed, it would have been apparent from the6
discussion of the prior art by Backlund and appellants, that one of ordinary skill in this art would have
known that the sequence QP, with and without an intervening washing step, was the LIGNOX process
of Lundgren and that it can be expanded to the sequences QPZ and QPZP, both of which are shown to
be alternative in Backlund and found among the sequences taught in Lindberg. It would have been
further apparent that the Q stage can be conducted under either acid conditions, as seen from Backlund
and Lindberg, and under neutral conditions, as seen from Lundgren and Lindberg, and that this stage is
advantageously used prior to a P stage in order to diminish, if not remove, the deleterious effect of
transitional metal ions on the peroxide, as seen in all three references. The references establish that it
was further known in the art that a Z stage, conducted under acid conditions, further delignifies the pulp
with certain advantageous results and generally follows the first P stage, and in turn is followed by a
second P stage.
One of ordinary skill in this art would have further found in Lindberg the teaching that a Z stage
may be the initial stage in a bleaching sequence following oxygen delignification with the affect of
dissolving transition metal as an alternative to the use of a Q stage conducted under acid or neutral
conditions for the same purpose. I find that this person would also have found in the disclosure of the
exemplary bleaching sequences ZEZP and QZEZP in Lindberg an example of a Z stage as the initial
stage and would have reasonably inferred from the latter sequence that the two stages, Q and Z, each
also disclosed as separately used as the initial stage of the bleaching sequence following oxygen
delignification, can be used sequentially and accomplish the purpose of dissolving metals from the pulp,
as this person would have expected that using a following Q stage would also chelate the metal ions
dissolved from the pulp in the Z stage. The use of a Z stage as the initial stage of the bleaching sequence
While the focus here has been on oxygen delignified pulp, as in claim 21, it is apparent that one of
ordinary skill in the art also had knowledge of the effect on non-oxygenated pulp as well. See, e.g.,
Lundgren, col. 5, lines 47-66.
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