WO2008044988A1 - Blanchiment de la pâte à papier - Google Patents

Blanchiment de la pâte à papier Download PDF

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Publication number
WO2008044988A1
WO2008044988A1 PCT/SE2007/050630 SE2007050630W WO2008044988A1 WO 2008044988 A1 WO2008044988 A1 WO 2008044988A1 SE 2007050630 W SE2007050630 W SE 2007050630W WO 2008044988 A1 WO2008044988 A1 WO 2008044988A1
Authority
WO
WIPO (PCT)
Prior art keywords
chlorine dioxide
pulp
bleaching
stage
final
Prior art date
Application number
PCT/SE2007/050630
Other languages
English (en)
Inventor
Magnus BJÖRKLUND
Thomas Christopher Greschik
Håkan FÄGERSTEN
Original Assignee
Akzo Nobel N.V.
Eka Chemicals Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=37807769&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO2008044988(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Akzo Nobel N.V., Eka Chemicals Ab filed Critical Akzo Nobel N.V.
Priority to ES07808867T priority Critical patent/ES2403371T3/es
Priority to BRPI0719893-0A2A priority patent/BRPI0719893A2/pt
Priority to EA200970367A priority patent/EA013901B1/ru
Priority to CA2665969A priority patent/CA2665969C/fr
Priority to EP07808867A priority patent/EP2082096B1/fr
Publication of WO2008044988A1 publication Critical patent/WO2008044988A1/fr
Priority to NO20091815A priority patent/NO20091815L/no

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
    • D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
    • D21C9/142—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 in a multistage process involving ClO2/Cl2 exclusively

Definitions

  • the present invention relates to a bleaching process which decreases the brightness reversion or yellowing of an ECF bleached pulp.
  • the target is to provide high and stable brightness levels.
  • brightness reversion or yellowing of pulp occurs to varying extent during storage and transportation to the paper mill depending on e.g. temperature, humidity, wood species, cooking conditions and bleaching sequence. It is therefore important to perform the bleaching so that the brightness reversion becomes as low as possible.
  • a standard elemental chlorine free (ECF) bleaching sequence is disclosed. The bleached pulp obtained from this sequence may, however, suffer from considerable brightness reversion.
  • the Ljungberg Textbook, Pulp Technology, 2004 generally discloses ECF bleaching in which brightness reversion may suffer from considerable brightness reversion. It would thus be of interest to provide a process further improving the brightness stability.
  • the present invention intends to provide such process, particularly for decreasing the brightness reversion of pulps derived from an alkaline pulping process with a certain content of hexenuronic acid prior to the final bleaching stage.
  • the present invention relates to a process of bleaching pulp derived from an alkaline pulping process having a hexenuronic acid content prior to the final bleaching stage from about 1 to about 80 mmol/kg dry pulp, said process comprising three chlorine dioxide stages DO, D1 , and D2, wherein the chlorine dioxide charges based on the total chlorine dioxide charge in a) DO is from about 40 to about 60 %; b) D1 is from about 30 to about 55 %; c) D2 is from about 4 to about 20 %, and wherein the final chlorine dioxide stage D2 is performed at a pH from about 2 to about 4.5.
  • the pulp to be bleached may be derived from lignocellulose-containing material which may comprise e.g. wood logs, finely-divided raw materials, and woody materials, such as wood particles and non-wood such as fibres of annual or perennial plants.
  • the woody raw material can be derived from hardwood or softwood species, such as birch, beech, aspen, alder, eucalyptus, maple, acacia, mixed tropical hardwood, pine, fir, hemlock, larch, spruce, and mixtures thereof.
  • Non-wood plant raw material can be provided from e.g.
  • pulp derived from recycled pulp may be used, either separately or in mixtures with virgin pulps.
  • the pulp can be a chemical pulp, produced using an alkaline pulping process, for example sulphate, soda processes or modifications thereof with optional additives such as anthraquinone, e.g. the soda anthraquinone (AQ) pulping process.
  • the chemical pulp obtainable from lignocellulose-containing materials may be subjected to one or more oxygen treatment stages subsequent to the pulping process.
  • the process can be applied to chemically digested pulps having an initial kappa number, i.e. a kappa number after digestion but before oxygen delignification, in the range from about 5 to about 40, for example from about 8 to about 30, or from about 8 to about 25
  • the referred kappa number is measured according to the ISO 302 Standard Method.
  • the content of hexenuronic acids in the bleached pulp prior to the final bleaching stage is from about 5 to about 80 or from about 5 to about 25, or from about 5 to about 15 mmol/kg dry pulp.
  • the pH of the first chlorine dioxide bleaching stage ranges from about 2 to about 4, for example from about 2.5 to about 3.5.
  • the pH of the second chlorine dioxide bleaching stage ranges from about 2.5 to about 4.5, for example from about 3 to about 4.
  • the pH of the final chlorine dioxide bleaching stage ranges from about 2 to about 4.4 or from about 2 to about 4.3, for example from about 2 to about 4 or from about 2 to about 3.5, such as from about 2 to about 3.4 or from about 2 to about 3.3 or from about 2.5 to about 3, or any other sub-range within the range from about 2.5 to about 4.5.
  • the temperature of the first chlorine dioxide bleaching stage ranges from about 40 to about 90, for example from about 50 to about 80 or from about 55 to about 70°C.
  • the temperature of the second chlorine dioxide bleaching stage ranges from about 70 to about 90, for example from about 80 to about 90°C.
  • the temperature of the final chlorine dioxide bleaching stage ranges from about 80 to about 100, for example from about 85 to about 100, or from about 87 to about 100 0 C.
  • the pulp consistency in the chlorine dioxide bleaching stages ranges from about 1 to about 40, for example from about 3 to about 30 or from about 5 to about 15 wt%.
  • the charge of chlorine dioxide charge based on the total chlorine dioxide charge in DO is from about 45 to about 55, for example from about 45 to about 50, or from about 45 to about 48 %.
  • the charge of chlorine dioxide charge based on the total chlorine dioxide charge in D1 is from about 35 to about 50, for example from about 40 to about 50, or from about 45 to about 50 %.
  • the charge of chlorine dioxide charge based on the total chlorine dioxide charge in D2 is from about 5 to about 15 , for example from about 5 to about 12, or from about 5 to about 10%.
  • the retention time of the first chlorine dioxide bleaching stage is from about 20 to about 60, for example from about 30 to about 50, or from about 35 to about 45 minutes.
  • the retention time of the second chlorine dioxide bleaching stage is from about 60 to about 240, for example from about 60 to about 120, or from about 60 to about 90 minutes.
  • the retention time in the final chlorine dioxide bleaching stage is from about 90 to about 360, for example from about 110 to about 240, or from about 110 to about 180 minutes.
  • the bleaching process may comprise besides chlorine dioxide stages for example ozone, peracid, oxygen and/or peroxide- containing, as well as enzyme-containing bleaching stages either in addition to the sequence of three chlorine dioxide stages or substituting any of the initial chlorine dioxide stages.
  • also washing and/or extraction stages, acidification and/or chelating agent stages may be present in the bleaching process preceeding, between and/or subsequent to any bleaching stages.
  • chlorine dioxide and chelating agent stages can be carried out without any make-up chemicals added, as both stages can be performed at similar pH ranges.
  • a chelating agent stage is carried out essentially in absence of chlorine dioxide, as essentially most of the chlorine dioxide is washed away by the washing stage.
  • an acid readily available in the pulp mill may be employed.
  • the pulp can be bleached with a peroxide-containing compound which can be an inorganic peroxide compound such as hydrogen peroxide or peroxomonosulphuric acid (caro's acid) or an inorganic peroxide compound like aliphatic peracids and aromatic peracids and salts thereof.
  • a peroxide-containing compound which can be an inorganic peroxide compound such as hydrogen peroxide or peroxomonosulphuric acid (caro's acid) or an inorganic peroxide compound like aliphatic peracids and aromatic peracids and salts thereof.
  • Suitable organic peroxides are peracetic acid and performic acid.
  • the peroxide-containing compound is hydrogen peroxide or a mixture of hydrogen peroxide and peracetic acid commonly referred to as equilibrium peracetic acid.
  • the pH of the pulp suspension is suitably above 7, for example in the range from about 7 to about 13, from about 8 to about 12, or from about 9.5 to about 1 1.5.
  • the temperature of the hydrogen peroxide bleaching may be from about 30 to about 130, for example from about 50 to about 100, or from about 50 to about 90 °C.
  • the length of the hydrogen peroxide treatment may be from about 3 to about 960, for example from about 10 to about 360, or from about 60 to about 240 minutes.
  • the amount of added hydrogen peroxide is from about 1 to about 60, for example from about 6 to about 50, or from about 13 to about 40 kg per tonne dry pulp.
  • Other bleaching agents may be added to the hydrogen peroxide bleaching stage such as oxygen.
  • the bleaching process comprises an ECF (Elemental Chlorine Free) or a substantially ECF sequence, for example according to the following sequence: DO(OP)DI nD2, where DO, D1 , and D2 indicate three chlorine dioxide (D) stages, OP indicates an oxygen-containing peroxide stage, and n indicates a neutral washing stage.
  • the bleached pulp is subsequently treated as an aqueous suspension prior to papermaking by dewatering and drying said suspension, wherein the pH of the suspension to be treated ranges from about 6.5 to about 12.
  • the bleached pulp may be further treated as set out in US appl.11/847374.
  • the invention also relates to a bleached pulp obtainable by the process defined herein.
  • the experiments were carried out employing an industrial oxygen-delignified eucalyptus pulp.
  • the characteristics of the oxygen-delignified pulp is shown in table 1.
  • the pulp could be characterized as a low bleaching chemical demand pulp with high content of hexenuronic acid (HexA).
  • the pulp had an unbleached kappa number of 10.7 and required 1.5 kg/t H 2 O 2 and 27 kg/t CIO 2 in the sequence DO(OP)DI nD2 to reach the brightness target 90.5% ISO.
  • the aim of the experiments was to improve a standard ECF sequence, DO(OP)DI nD2, in view of brightness reversion within the limitations of an existing mill.
  • DO(OP)DI nD2 DO(OP)DI nD2
  • the conditions in the D1 and D2 stages and the distribution of chlorine dioxide were varied whereas the conditions in the DO and (OP) stages were kept constant.
  • the retention time and temperature in the DO stage were 45 minutes and 60°C.
  • the (OP) stage was performed at a pressure of 0.5 MPa, a retention time of 60 minutes, a temperature of 8O 0 C and a final pH between 1 1.6 and 11.9.
  • the hydrogen peroxide (H 2 O 2 ) dosage was 1.5 kg/t on oven dry pulp in all experiments.
  • the pulp and chemicals were mixed at 10 wt% pulp consistency and distributed uniformly in polypropylene bags, the atmosphere of which was saturated with oxygen.
  • the plastic bags were sealed and placed in autoclaves which were pressurized with oxygen.
  • the chlorine dioxide dosages were given as active chlorine.
  • the consistency was 10 wt% in all bleaching stages. All non-pressurised stages were carried out in sealed plastic polyethylene bags.
  • the pulp was washed with distilled water.
  • the pH was adjusted to between 7 and 10 with NaOH.
  • the kappa number and ISO brightness were determined according to ISO 302 and ISO 2470 respectively.
  • the hexenuronic acid was determined by acidic hydrolysis of the pulp in a formate buffer followed by UV analysis of the 2-furoic acid formed in the hydrolysate. The accelerated heat-induced brightness reversion was evaluated as humid brightness reversion.
  • the "humid brightness reversion" was evaluated by measuring the brightness loss after the sheet had been conditioned at 23°C and 50% relative humidity, sealed in a polyethylene bag, kept at 70°C for 64h and finally removed from the bag and allowed to temperate at room temperature for at least 1 h.
  • the brightness reversion was reported as the difference in ISO brightness units before and after reversion treatment.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

La présente invention concerne un procédé de blanchiment de la pâte à papier issue d'un procédé de fabrication de pâte en milieu alcalin, ayant une teneur en acide hexenuronique avant le stade de blanchiment final d'environ 1 à environ 80 mmol/kg de pâte sèche. Ledit procédé comprend trois stades au dioxyde de chlore D0, D1 et D2. Les charges de dioxyde de chlore sur la base de la charge totale de dioxyde de chlore sont dans a) D0 d'environ 40 à environ 60 % ; b) D1 d'environ 30 à environ 55 % ; c) D2 d'environ 4 à environ 20 %, et le stade final au dioxyde de chlore D2 est effectué à un pH d'environ 2 à environ 4,5. L'invention concerne également une pâte à papier blanchie pouvant être obtenue par le procédé.
PCT/SE2007/050630 2006-10-11 2007-09-06 Blanchiment de la pâte à papier WO2008044988A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
ES07808867T ES2403371T3 (es) 2006-10-11 2007-09-06 Blanqueo de pasta papelera
BRPI0719893-0A2A BRPI0719893A2 (pt) 2006-10-11 2007-09-06 Branqueamento de polpa
EA200970367A EA013901B1 (ru) 2006-10-11 2007-09-06 Отбеливание целлюлозы
CA2665969A CA2665969C (fr) 2006-10-11 2007-09-06 Blanchiment de la pate a papier
EP07808867A EP2082096B1 (fr) 2006-10-11 2007-09-06 Blanchiment de la pâte à papier
NO20091815A NO20091815L (no) 2006-10-11 2009-05-08 Bleking av tremasse

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06122119 2006-10-11
EP06122119.8 2006-10-11

Publications (1)

Publication Number Publication Date
WO2008044988A1 true WO2008044988A1 (fr) 2008-04-17

Family

ID=37807769

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2007/050630 WO2008044988A1 (fr) 2006-10-11 2007-09-06 Blanchiment de la pâte à papier

Country Status (12)

Country Link
EP (1) EP2082096B1 (fr)
AR (1) AR063160A1 (fr)
BR (1) BRPI0719893A2 (fr)
CA (1) CA2665969C (fr)
CL (1) CL2007002906A1 (fr)
EA (1) EA013901B1 (fr)
ES (1) ES2403371T3 (fr)
NO (1) NO20091815L (fr)
PT (1) PT2082096E (fr)
UY (1) UY30634A1 (fr)
WO (1) WO2008044988A1 (fr)
ZA (1) ZA200903205B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012022840A1 (fr) 2010-08-18 2012-02-23 Åbo Akademi University Procédé d'élimination d'acides hexenuroniques
US9970157B2 (en) 2013-08-09 2018-05-15 Novozymes A/S Reducing content of hexenuronic acids in cellulosic pulp

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3501374A (en) * 1968-12-26 1970-03-17 Hooker Chemical Corp Sequential bleaching of kraft pulp with chlorine dioxide and chlorine
US5030324A (en) * 1990-01-29 1991-07-09 Champion International Corporation Sequential bleaching procedure using chlorine and chlorine dioxide in a first chlorination stage of a multistage bleaching process
US5268075A (en) * 1989-10-19 1993-12-07 North Carolina State University High efficiency two-step, high-low pH chlorine dioxide pulp bleaching process
EP0940498A1 (fr) * 1998-03-06 1999-09-08 Ahlstrom Machinery Oy Procédé pour le traitement de pâte à papier
EP1270805A2 (fr) * 2001-06-06 2003-01-02 Kvaerner Pulping Ab Réduction du chlore lié organiquement formé dans le blanchiment par le dioxyde de chlore
US6776876B1 (en) * 1994-10-13 2004-08-17 Andritz Oy Method of treating cellulosic pulp to remove hexenuronic acid
US20060201642A1 (en) * 2005-03-08 2006-09-14 Andritz Inc. Methods of treating chemical cellulose pulp

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3501374A (en) * 1968-12-26 1970-03-17 Hooker Chemical Corp Sequential bleaching of kraft pulp with chlorine dioxide and chlorine
US5268075A (en) * 1989-10-19 1993-12-07 North Carolina State University High efficiency two-step, high-low pH chlorine dioxide pulp bleaching process
US5030324A (en) * 1990-01-29 1991-07-09 Champion International Corporation Sequential bleaching procedure using chlorine and chlorine dioxide in a first chlorination stage of a multistage bleaching process
US6776876B1 (en) * 1994-10-13 2004-08-17 Andritz Oy Method of treating cellulosic pulp to remove hexenuronic acid
EP0940498A1 (fr) * 1998-03-06 1999-09-08 Ahlstrom Machinery Oy Procédé pour le traitement de pâte à papier
EP1270805A2 (fr) * 2001-06-06 2003-01-02 Kvaerner Pulping Ab Réduction du chlore lié organiquement formé dans le blanchiment par le dioxyde de chlore
US20060201642A1 (en) * 2005-03-08 2006-09-14 Andritz Inc. Methods of treating chemical cellulose pulp

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012022840A1 (fr) 2010-08-18 2012-02-23 Åbo Akademi University Procédé d'élimination d'acides hexenuroniques
US9970157B2 (en) 2013-08-09 2018-05-15 Novozymes A/S Reducing content of hexenuronic acids in cellulosic pulp
US10570562B2 (en) 2013-08-09 2020-02-25 Novozymes A/S Methods for reducing content of hexenuronic acids in cellulosic pulp

Also Published As

Publication number Publication date
EA200970367A1 (ru) 2009-08-28
EP2082096A1 (fr) 2009-07-29
BRPI0719893A2 (pt) 2014-05-06
UY30634A1 (es) 2007-11-30
NO20091815L (no) 2009-07-10
ES2403371T3 (es) 2013-05-17
CA2665969C (fr) 2016-04-12
ZA200903205B (en) 2010-03-31
EP2082096B1 (fr) 2013-02-20
AR063160A1 (es) 2008-12-30
EA013901B1 (ru) 2010-08-30
CA2665969A1 (fr) 2008-04-17
PT2082096E (pt) 2013-04-26
CL2007002906A1 (es) 2008-05-02

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