US 7,320,741 B2 | ||
Method of xylanase treatment in a chlorine dioxide bleaching sequence | ||
Jeffrey S. Tolan, Ottawa (Canada); Corina Popovici, Ottawa (Canada); and Luc Thibault, Casselman (Canada) | ||
Assigned to Iogen Bio-Products Corporation, Ontario (Canada) | ||
Appl. No. 10/466,640 PCT Filed Jan. 18, 2002, PCT No. PCT/CA02/00065 § 371(c)(1), (2), (4) Date Nov. 12, 2003, PCT Pub. No. WO02/057541, PCT Pub. Date Jul. 25, 2002. |
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Claims priority of provisional application 60/262858, filed on Jan. 18, 2001. | ||
Prior Publication US 2004/0077071 A1, Apr. 22, 2004 | ||
This patent is subject to a terminal disclaimer. | ||
Int. Cl. D21C 3/18 (2006.01) |
U.S. Cl. 162—73 [162/74; 162/78; 8/101; 8/107; 8/115; 8/51; 435/278] | 3 Claims |
1. A method of bleaching chemical pulp in the absence of a peroxyacid, said method comprising the steps of
a) exposing said chemical pulp to a first chlorine dioxide bleaching stage (D-Stage) to produce a partially bleached pulp;
b) treating said partially bleached pulp with a xylanase in an enzyme treatment stage at a pH of about 3 to about 8 to produce
an enzymatically treated pulp;
c) extracting said enzymatically treated pulp in an alkaline extraction stage to produce an extracted pulp; and
d) re-exposing said extracted pulp to a second bleaching stage.
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