Appeal No. 1998-2077
Application 08/553,324
would also have been reasonably expected by one of ordinary skill in this art to result in further
delignification of the pulp and accompanying reduction in the kappa number of the pulp, characteristic of
this stage, at this point in the sequence. In this respect, Lundgren would have reasonably suggested that
a second successive stage using oxygen can be used in a bleaching sequence that begins with oxygen
delignification. I find that one of ordinary skill in this art would have recognized from the references that
the purposes of the washing steps between the stages in the bleaching sequences are the removal of
materials used in and resulting from a bleaching stage from the pulp, such as complex bound metals, thus
preparing the pulp to receive materials during the next bleaching stage, and for control of the material
thus used in and generated in the bleaching process. Indeed, Lindberg teaches that washing “step (b)”
follows the step of dissolving the transition metals in “step (a).”
In comparing the claimed method encompassed by the appealed claims considered here (see
above note 2) with the combined teachings of the prior art as discussed above, it is apparent that the
principal issue with respect to whether the examiner has made out a prima facie case of obviousness, is
whether one of ordinary skill in this art would have found in the combined teachings of the applied
references the reasonable suggestion to use a Z stage followed by a Q stage, without an intervening
washing step, as the initial stages to be followed by a P stage in a bleaching sequence for oxygen
delignified pulp, with the reasonable expectation of affecting the kappa number and thus the brightness of
the pulp. The examiner points out that Lindberg teaches that either the Z stage or the Q stage can be
used as the initial stage to remove metal ions and that the Z stage would be the first bleaching stage in the
bleaching sequence even in the sequence QZEZP (answer, page 4). I additionally found above that this
sequence, when compared to the sequence ZEZP, further would have reasonably suggested that the two
stages, Z and Q, taught by Lindberg for the purpose noted by the examiner, could be sequentially used
in a sequence, and Lindberg does teach that the Z stage can be the initial staged in the bleaching
process. Indeed, the Z stage would additionally perform the function of further delignifing the pulp, thus
lowering the kappa number and increasing the brightness, regardless of the position of this step in the
sequence, as shown by the references.
Thus, based on this evidence, I agree with the examiner that, prima facie, one of ordinary skill
in this art would have reasonably found in Lindberg the suggestion that the Z stage can precede the Q
stage to be followed by a P stage in a bleaching sequence with the reasonable expectation that the pulp
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