Appeal No. 1996-0647
Application No. 07/871,401
According to appellant, the invention is directed to both
a method of bleaching kraft wood pulp and a kraft pulp product
with good brightness, viscosity and reduced toxins which
method comprises bleaching the pulp with chlorine dioxide or a
mixture of chlorine dioxide and chlorine followed by ozonation
using specified ratios of chlorine and ozone (Brief, page 3). 2
Claims 1, 7 and 8 are illustrative of the subject matter on
appeal and are reproduced below:
1. A method for the treatment of kraft pulp in preparation
for its use in papermaking comprising the steps of:
contacting said pulp while dispersed in an aqueous medium
with an initial charge of a chlorine-based bleaching agent
selected from the group consisting of chlorine dioxide, and
mixtures of chlorine dioxide and chlorine, wherein the total
chlorine dioxide present in said charge represents between
about 100% and about 50% of the total charge, expressed as
effective chlorine, the remainder of said charge being
chlorine, said bleaching agent producing a substantial
quantity of chlorine-containing moieties that are insoluble in
an acid medium,
thereafter, and prior to any intervening treatment of
said pulp other than a wash, contacting said pulp with ozone,
said ozone being present in an amount which provides a ratio
of "C" factor to % ozone, based on dry weight of pulp, from
about 0.036 to about 0.7 for a period of time sufficient to
cause said ozone to oxidize substantial quantities of said
2All citation from the "Brief" is from the amended Brief
dated Feb. 18, 1997, Paper No. 38.
2
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