Appeal No. 1998-2077
Application 08/553,324
would be affected with respect to the presence of transition metal ions and further delignified, and thus
would have reasonably found in the combined teachings of the references the suggestion to modify the
bleaching sequences QPZ and QPZP that were will known in the art by inserting a Z stage as the initial
stage prior to the Q stage, thus arriving at the sequences, inter alia, ZQPZ and ZQPZP, encompassed
by the claimed processes encompassed by claim 23. I further agree with the examiner (answer, pages 4
and 5-6) that, prima facie, one of ordinary skill in this art would have found in the combined teachings
of the references the further suggestion that a washing step need not be used between the Z and Q
stages because both stages are taught by Lindberg to affect the presence of the transition metal ions.
Indeed, the removal of such ions dissolved from the pulp by successive stages in one washing step
would be efficacious with respect to the treatment of washing filtrates, which is an objective of those of
ordinary skill in this art as evinced by the applied references, such as the processing of the filtrate from
washing “step (b)” that follows the step of dissolving the transition metals in “step (a)” in Lindberg.
With respect to claim 1, which differs from claim 23 in further requiring that the pulp is adjusted
to a pH exceeding 3 by adding alkali with of after the addition of the chelating agent in the Q stage, the
addition of the alkali with the chelating agent specified in claim 20, Lundgren teaches the use of a
chelating agent at a pH of 3.1 up to 9.0 and Lindberg teaches the use of the chelating agent EDTA with
and without acid. Accordingly, prima facie, one of ordinary skill in this art would have found in these
references the suggestion to use the chelating agent EDTA at a pH exceeding 3 as required by the claim,
and would further have used an alkali to achieve this result by routine experimentation (see answer, page
6) as neither reference specifies how the pH of 3.1 up to 9 must be arrived at. With respect to claim 21,
it is apparent that each of the applied references discloses methods employing oxygen delignified pulp.
With respect to claim 22, as pointed out above, a Z stage was used before a second P stage in the
bleaching sequences of Backlund and Lindberg, as well as in the extension of the process of Lundgren
known in the art, as described by Backlund and acknowledged by appellants, as found above, which
references make it clear that the advantage of a Z stage preceding a P stage is increased brightness.
Accordingly, based on this evidence, prima facie, one of ordinary skill in this art would have
found in the combined teachings of the references the clear suggestion that an acid Z stage followed by a
Q stage with the addition of alkali, without intervening washing step can be used as the initial sequence to
be followed by a P stage in a bleaching sequence for oxygen delignified pulp, resulting in the sequences,
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