Appeal No. 2002-0456 Page 3
Application No. 09/155,995
[Additionally,] it was found that the rigidity of the polysaccharides was
considerably improved when the cross-linking agent used was
monofunctional but also contained an additional masked functional group
that could be activated later. The cross-linking was made in two steps.
First the polysaccharide was derivatized with the monofunctional group.
Then, in the next step the masked group was activated and made to react
with the hydroxyl groups of the polysaccharide.
According to appellant, “the state of the art [ ] is that the cross-linking is made on
the polysaccharide polymer after the formation of the gel . . . [t]hus, the cross-linking is
made on the ready made structure.” Specification, page 2. The present invention, on
the other hand, is directed to cross-linked polysaccharide gels, and methods of making
them, in which a bifunctional cross-linking agent “is introduced into the polysaccharide
solution or dispersion before the gel formation . . . the active site of the [bifunctional
cross-linking] agent is allowed to react with the hydroxyl groups of the polysaccharide”
and “thereby . . . is chemically bound to the polymer chains before the gel formation
process is started.” Id., page 4. “In this manner an internal cross-linking agent is
introduced into the polysaccharide,” resulting in cross-linked polysaccharide gels “with
improved capability to withstand high flow rates/back pressures, but with retained
separation qualities.” Id., page 3.
DISCUSSION
According to the examiner, Lindgren “discloses the essential details of the instant
process . . . [and] is directed to the same subject matter” except for “the use of an
organic solvent in the gelling[ ] process step.” Answer, page 4. Based on his findings,
the examiner concludes that “[t]he disclosure in [Lindgren] . . . is deemed to render the
instant claimed compound produced and the instant claimed process lacking in
patentable distinction in the absence of unexpected results.” Id.
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