Appeal No. 1999-0791
Application No. 08/754,884
improved considerably, as can be seen in Fig. 1.
Further controlled experiments indicated that acid
pretreatment was advantageous because it removed
metals which presumably catalyzed the degradation of
peroxide. Out of eight metals found in the pulp (Al,
Ca, Cu, Fe, Mg, Mn, Na, Ti), Cu, Mn, and Fe showed
definite trends with brightness. Maximum brightness
was obtained when acid pretreatment was carried out at
a pH below 3.0. The effect of metal ions on peroxide
bleaching was checked by washing the acid-treated
pulps with waters containing 100 ppm of Mg, Fe, or Mn.
Deionized water was used only in the case of Mg.
Pulps washed with waters containing Fe or Mn did not
show any improvement in brightness after peroxide
bleaching, whereas those with Mg did. Apparently,
some metal ions are responsible for the lower
bleaching response of unbleached kraft pulp with
peroxide.
(Page 108; underlining added.)
Contrary to the examiner's stated position (examiner's
answer page 4), nowhere in Ruhanen is there a teaching or
suggestion that it is the Mg which causes the improvement in
brightness. That is, Ruhanen's disclosure would not have
suggested to one of ordinary skill in the art that the presence
of Mg ions results in an improvement in terms of brightness
above and beyond the improvement that would be obtained after
hydrogen peroxide bleaching in the absence of any metal ions.
Instead, Ruhanen merely suggests that Mg, unlike other metal
ions, did not have any effect on the bleaching properties of
hydrogen peroxide. Thus, we determine that Ruhanen does not
4
Page: Previous 1 2 3 4 5 6 Next
Last modified: November 3, 2007