Appeal No. 2005-0440
Application No. 09/994,075
The subject matter on appeal relates to a method of
inhibiting alkaline darkening of a mechanical pulp in the
presence of a calcium carbonate filler. Further details of this
appealed subject matter are recited in representative claim 1
reproduced below:
1. A method of inhibiting alkaline darkening of
a mechanical pulp in the presence of a calcium
carbonate filler comprising:
providing an aqueous suspension of a mechanical
pulp for producing paper, and
incorporating in said suspension a calcium
carbonate filler for producing paper with the pulp,
and a sulphite to inhibit alkaline darkening of said
pulp in said suspension arising from the calcium
carbonate filler in the suspension.
In addition to the appellants’ admitted prior art
(specification at page 2, lines 13-21), the examiner relies on
the following prior art references as evidence of
unpatentability:
Hovey 2,173,167 Sep. 19, 1939
Tsukamoto et al. 4,183,146 Jan. 15, 1980
(Tsukamoto)
Eckert 4,427,490 Jan. 24, 1984
Evans et al. 5,882,476 Mar. 16, 1999
(Evans) (filed May 5, 1995)
Nye H1690 Nov. 04, 1997
(published US Statutory Invention
Registration)
2
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