Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Chemical treatment after start or completion of mechanical...
Reexamination Certificate
2008-06-10
2008-06-10
Hug, Eric (Department: 1791)
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Chemical treatment after start or completion of mechanical...
C162S018000, C162S027000, C162S028000, C162S056000, C162S060000, C162S071000, C162S090000, C162S091000
Reexamination Certificate
active
07384502
ABSTRACT:
Wood chips having low bleachability are impregnated with a chemical liquor at a pH range of 7-12 in aqueous solution and the chemical liquor from the impregnated chips is drained, whereby extractives contained in the chips and consuming bleaching agents can be removed to improve the effect of bleaching agents in a subsequent bleaching step. Bleached mechanical pulp is prepared by defibration by primary refining—bleaching—beating by secondary refining wherein pulp fibers are washed after defibrating wood chips having low bleachability and before bleaching the pulp fibers, whereby the amount of bleaching agents used can be reduced and bleached mechanical pulp having a Hunter brightness of 45-65% after secondary refining can be obtained.
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Kamijo Yasuyuki
Miyanishi Takanori
Onodera Isao
Watanabe Keigo
Hug Eric
Nippon Paper Industries Co. Ltd.
Roylance Abrams Berdo & Goodman L.L.P.
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