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1. (WO1991017306) BLEACHING OF CHEMICAL PULP
Latest bibliographic data on file with the International Bureau

Pub. No.: WO/1991/017306 International Application No.: PCT/SE1991/000178
Publication Date: 14.11.1991 International Filing Date: 07.03.1991
Chapter 2 Demand Filed: 20.09.1991
IPC:
D21C 9/10 (2006.01) ,D21C 9/14 (2006.01) ,D21C 9/147 (2006.01) ,D21C 9/16 (2006.01) ,D21H 17/00 (2006.01)
D TEXTILES; PAPER
21
PAPER-MAKING; PRODUCTION OF CELLULOSE
C
PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE- CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9
After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters
10
Bleaching
D TEXTILES; PAPER
21
PAPER-MAKING; PRODUCTION OF CELLULOSE
C
PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE- CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9
After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters
10
Bleaching
12
with halogens or halogen-containing compounds
14
with ClO2 or chlorites
D TEXTILES; PAPER
21
PAPER-MAKING; PRODUCTION OF CELLULOSE
C
PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE- CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9
After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters
10
Bleaching
147
with oxygen or its allotropic modifications
D TEXTILES; PAPER
21
PAPER-MAKING; PRODUCTION OF CELLULOSE
C
PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE- CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9
After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters
10
Bleaching
16
with per compounds
D TEXTILES; PAPER
21
PAPER-MAKING; PRODUCTION OF CELLULOSE
H
PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C, D21D84; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G97; PAPER NOT OTHERWISE PROVIDED FOR
17
Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
Applicants:
SUNDS DEFIBRATOR INDUSTRIES AKTIEBOLAG [SE/SE]; S-851 94 Sundsvall, SE (AllExceptUS)
FÄRNSTRAND, Per-Åke [SE/SE]; SE (UsOnly)
SJÖDIN, Lars, T. [SE/SE]; SE (UsOnly)
LINDSTRÖM, Lars-Åke [SE/SE]; SE (UsOnly)
NORDÉN, K., Solveig, E. [SE/SE]; SE (UsOnly)
Inventors:
FÄRNSTRAND, Per-Åke; SE
SJÖDIN, Lars, T.; SE
LINDSTRÖM, Lars-Åke; SE
NORDÉN, K., Solveig, E.; SE
Agent:
SUNDQVIST, Hans; Sunds Defibrator Industries Aktiebolag Rålambsvägen 7 S-112 59 Stockholm, SE
Priority Data:
9001548-830.04.1990SE
Title (EN) BLEACHING OF CHEMICAL PULP
(FR) BLANCHIMENT DE LA CELLULOSE CHIMIQUE
Abstract:
(EN) A method of bleaching chemical pulp in a sequence comprising at least four bleaching steps with final bleaching in a first and a second chlorine dioxide step. Between the chlorine dioxide steps an alkaline extraction is carried out, and washing takes place between the first chlorine dioxide step and extraction. Immediately after said washing step, NaOH is charged in an amount of 4-10 kg/ton pulp. Thereafter an oxidizing agent is admixed in an amount of at maximum 2 kg/ton pulp. After 15-120 seconds an acid is added for terminating the oxidation treatment and for lowering the pH-value, but without effecting a complete neutralization of residual alkaline.
(FR) Procédé de blanchiment de la cellulose chimique comprenant au moins quatre étapes de blanchiment avec blanchiment final dans une première et une deuxième étape au dioxyde de chlore. Entre les étapes au dioxyde de chlore a lieu une extraction alcaline, et le lavage s'effectue entre la première étape au dioxyde de chlore et l'extraction. Immédiatement après le lavage, on ajoute de 4 à 10 kg de NaOH par tonne de cellulose. Est ensuite incorporé un agent oxydant à raison de 2 kg au plus par tonne de cellulose. Après 15 à 20 secondes, on ajoute un acide pour achever le traitement oxydant et pour abaisser le pH, mais sans neutralisation complète des alcalis résiduels.
Designated States: AU, BR, CA, FI, JP, NO, US
European Patent Office (AT, BE, CH, DE, DK, ES, FR, GB, GR, IT, LU, NL, SE)
Publication Language: English (EN)
Filing Language: English (EN)
Also published as:
FI924889NO19924182ES2055602EP0527808US5589031JPH05506698
CA2080242DE000069102430PT97537AU1991077427