Appeal No. 2004-1877
Application No. 09/178,512
"at the completion of the cook may approach 5 g/L or lower"
(page 2 of specification, lines 10-11). Appellants' specification
also discloses that work done by the Swedish research firm STFI
employed an initial alkali concentration of 10-15 g/L and a
concentration of 5-10 g/L at the end of the cook (see page 2 of
specification, third paragraph). Hence, based on the state of the
prior art, we are convinced that it would have been obvious for
one of ordinary skill in the art to perform the treatment method
of Chasse in accordance with the protocol recited in claim 1 on
appeal.
Furthermore, we agree with the examiner that Sandström
provides additional evidence that it was known in the art to use
the low alkali concentrations in the three claimed treating steps
in order to increase the delignification selectivity, increase the
pulp strength and consume less bleaching chemicals. Sandström
teaches that "[t]he difference in alkali concentration between the
liquor in chips and the free liquor is descreased [sic] from
45 g/l to 5 g/l at the point of temperature increase (130°-170°C)
at t=30 minutes" (page 34, second column, last sentence). Since
Figure 7 of SandstrÇm illustrates that the alkali concentration
at higher temperatures is well below 30 g/L, it follows that the
alkali concentration of the free liquor is also kept below 30 g/L.
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