WO2007085579A1 - Procédé pour le blanchiment de pâte à papier mécanique - Google Patents

Procédé pour le blanchiment de pâte à papier mécanique Download PDF

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Publication number
WO2007085579A1
WO2007085579A1 PCT/EP2007/050578 EP2007050578W WO2007085579A1 WO 2007085579 A1 WO2007085579 A1 WO 2007085579A1 EP 2007050578 W EP2007050578 W EP 2007050578W WO 2007085579 A1 WO2007085579 A1 WO 2007085579A1
Authority
WO
WIPO (PCT)
Prior art keywords
pretreatment step
process according
pulp
bleaching
paper pulp
Prior art date
Application number
PCT/EP2007/050578
Other languages
English (en)
Inventor
Rodney Seccombe
Pierre Dournel
Original Assignee
Solvay (Société Anonyme)
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
Application filed by Solvay (Société Anonyme) filed Critical Solvay (Société Anonyme)
Priority to EP07704046.7A priority Critical patent/EP1979533B1/fr
Priority to US12/160,805 priority patent/US20100163193A1/en
Priority to CA2636355A priority patent/CA2636355C/fr
Publication of WO2007085579A1 publication Critical patent/WO2007085579A1/fr

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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
    • D21C9/1026—Other features in bleaching processes
    • D21C9/1042—Use of chelating agents
    • 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
    • D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
    • 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
    • D21C9/16—Bleaching ; Apparatus therefor with per compounds

Definitions

  • the present invention is related to a process for the bleaching of mechanical paper pulp with one or more peroxide oxidizing agents, in which the paper pulp is pretreated with a chelating agent.
  • Powerful chelating agents can be of the aminocarboxylic type, such as ethylene diamine tetra-acetic acid and its salts (EDTA), or diethylene triamine penta-acetic acid and its salts (DTPA). Nevertheless, these chelating agents are poorly biodegradable which can generate environmental problems.
  • EDTA ethylene diamine tetra-acetic acid and its salts
  • DTPA diethylene triamine penta-acetic acid and its salts
  • biodegradable chelating agents such as aspartic acid and its derivatives, substituted on the nitrogen, is described in the international application WO 97/30209.
  • Such products include ethylenediamine-N,N'- disuccinic acid (EDDS) and 2,2'-imino-disuccinic acid (IDS).
  • EDDS ethylenediamine-N,N'- disuccinic acid
  • IDDS 2,2'-imino-disuccinic acid
  • the pretreatment step is conducted at a pH from 4 to 8.
  • a first disadvantage of this process is that it does not conduct to an optimal brightness of the paper pulp.
  • a second disadvantage is that the pH of the pretreatment step must be measured and maintained in a range from 4 to 8 during the whole step.
  • the international application WO 99/46441 describes a process for the bleaching of mechanical paper pulp with one or more peroxide oxidizing agents, in which the pulp is pretreated with one or more chelating agents chosen from aspartic acid and its derivatives, substituted on the nitrogen, and at a pH above 8.
  • the pH of the pretreatment step must be measured during the whole step and must be maintained above 8.
  • the purpose of the present invention is to provide a simplified bleaching process, avoiding measurement and control of the pH during the pretreatment step, conducting to an optimal brightness of the paper pulp, while still using biodegradable chelating agents during the pretreatment step.
  • the present invention therefore relates to a process for the bleaching of mechanical paper pulp with one or more peroxide oxidizing agents, in which the pulp is pretreated in a pretreatment step with one or more chelating agents chosen from aspartic acid and its derivatives, substituted on the nitrogen atom, characterized in that the initial pH of the pretreatment step, just before adding the one or more chelating agents, is above 8.
  • One of the essential features of the present invention resides in solely controlling the initial pH of the pretreatment step, which must be above 8 just before adding the one or more chelating agents, and not measuring it after the addition of the chelating agent, and so until the end of the pretreatment step. It has indeed surprisingly been found that, as the critical pH of the pretreatment step is its initial pH, it is therefore not necessary to control it anymore during the rest of the pretreatment step. This is important as it is known that, due to alkaline demand of the paper pulp, the pH will naturally decrease with time. According to this invention, it is not necessary to measure it during the pretreatment step, nor to keep it above 8 by the addition of pH modifying compounds. It follows therefrom that the pretreatment step of the process is advantageously simplified.
  • mechanical paper pulps paper pulps obtained by mechanical treatment.
  • paper pulps are pressure groundwood (PGW), stone groundwood (SGW), thermomechanical pulp (TMP), refiner mechanical pulp (RMP), chemithermomechanical pulp (CTMP) and alkaline peroxide mechanical pulp (APMP or APP).
  • initial pH of the pretreatment step is meant the pH of the paper pulp just before the addition of one or more chelating agents.
  • the pH is measured using equipment normally found in pulp mills for such a purpose.
  • control of pH is meant the adjustment of the pH to a certain value.
  • pH modifying compounds examples include caustic soda (NaOH) or suitable alternative bases.
  • NaOH caustic soda
  • these compounds are alkalis because the natural pH of mechanical pulps is generally lower than the one required in practice for efficient control of metal ions.
  • the chelating agent used in the pretreatment step is chosen from aspartic acid and its derivatives, substituted on the nitrogen.
  • the chelating agent can particularly be chosen from N-carboxymethylaspartic acid, N-(l,2-dicarboxyethyl)-aspartic acid, N-(l,2-dicarboxy-2-hydroxyethyl)- aspartic acid, and compounds according to the formula :
  • n is 1-3, m is 0-3, p is 1-3, R 1 , R 2 , R 3 and R 4 are H, Na, K, Ca or Mg, R5 and R 6 are H, CH 2 OH, CH 2 CH 2 OH or CH 2 O(CH 2 CH 2 O) I-IO CH 2 CH 2 OH, and mixtures thereof.
  • An especially suitable chelating agent is, for example, ethylenediamine-N,N'-disuccinic acid (EDDS), its various isomers or its alkali metal salts or its earth-alkali metal salts.
  • Another especially suitable chelating agent is 2,2'-iminodisuccinic acid (IDS), its various isomers or its alkali metal salts or its earth-alkali metal salts.
  • the paper pulp is pretreated with one or more chelating agents at an initial pH of at least 8,1.
  • the pH is in most cases maximum 11. Within this range, the optimum must be established for each particular pulp.
  • the optimal pH is for example equal to or higher than 8,5.
  • the optimal pH is equal to or higher than 9, and for others it is equal to or higher than 10.
  • the pretreatment step with one or more chelating agent is usually carried out at the temperature generated by the mechanical treatment of the wood.
  • the temperature can vary widely and is usually at least 40 0 C. It is generally less than or equal to 95°C. The temperature may vary from 40 to 95°C.
  • the pretreatment step with one or more chelating agent is carried out in the presence of water in order to reach a consistency of at least 1 % by weight of dry paper pulp.
  • the consistency of the paper pulp is usually less than or equal to 50 % by weight of dry paper pulp.
  • the consistency of the paper pulp can be highly variable within the range from 1 to 50 % by weight of dry paper pulp and will be adapted to the type of equipment available for mixing the chelating agents into the process. In the majority of the cases, a consistency of less than or equal to 10 % by weight of dry paper pulp, for instance from 3 to 4 % by weight of dry paper pulp, will be suitable. In special cases, higher values, up to 45 % by weight of dry paper pulp can be used.
  • the chelating agent used in the pretreatment step is used at a concentration by weight of dry paper pulp of at least 0.1 %.
  • the concentration of the chelating agent by weight of dry paper pulp is usually less than or equal to 1,5 %.
  • the concentration of the chelating agent is highly variable within this range and must be optimized, depending on the paper mill. Typical values range from 0,2 to 1,0 % by weight of dry paper pulp. It is recommended to have a good mixing of the paper pulp with the chelating agent during the pretreatment step. This can be done by introducing the chelating agent via the pump circulating the pulp through the paper mill.
  • the duration of the pretreatment step with one or more chelating agent is usually from 5 to 120 minutes, varying from mill to mill. Good results are obtained provided the duration of the pretreatment step is of at least 5 minutes duration before the washing step.
  • the oxidizing agent used in the bleaching step is usually chosen from hydrogen peroxide, organic peracids such as peracetic acid, and/or a combination thereof.
  • the oxidizing agent is preferably hydrogen peroxide, which is advantageously used in an alkaline medium.
  • a washing step is usually conducted between the pretreatment step with one or more chelating agent and the bleaching step with a peroxide oxidizing agent.
  • the pretreatment step is conducted at a pH above 8.
  • the pretreatment step is conducted at a pH between 4 and 8, according to the international application WO 97/30209.
  • the pH was measured with a Knick Portamess pH-meter (911 pH), with an Ag/AgCl electrode (Mettler Toledo, U402-S7/120).
  • the electrolyte was a mixture KCl / AgCl 3M.
  • the temperature was compensated with a Knick PtIOOO (ZU0156) probe.
  • the pH-meter was calibrated with buffer solutions from Mettler Toledo (pH 7,00 buffer with the reference 9865 and pH 4,01 buffer with the reference 9863).
  • the brightness of paper pulp was measured using a Datacolor Elrepho spectrophotometer (SF450) according to the ISO standard 2470.
  • Example 1 (according to the invention), C2 & C3 (comparative)
  • TMP mechanical paper pulp
  • EDDS EDDS
  • water diluted with water prior to thickening
  • the pretreatment step was carried out at 60 0 C, during 20 minutes, at a consistency of 10 % by weight of dry pulp and with a concentration of 0,3 % in EDDS.
  • Initial pH of the pretreatment step of examples 1, C2 and C3 was respectively 9,8, 6,0 and 5,0.
  • the pH was measured with the standard laboratory glass electrode described above. The pH was not measured nor adjusted after the addition of the chelating agent, until the end of the pretreatment step.
  • the washing step was carried out by diluting the pulp to 4 % consistency with water and then thickening it with a press to a consistency around 20 %.
  • the bleaching step was carried out at 70 0 C, during 120 minutes, at a consistency of 15 % by weight of dry pulp, with a bleach liquor containing 3 % hydrogen peroxide, 2.3 % NaOH, and 2 % sodium silicate by weight of dry pulp.
  • TMP mechanical paper pulp
  • the pretreatment step was carried out at 60 0 C, during 45 minutes, at a consistency of 10 % by weight of dry pulp and with a concentration of 0.3 % in IDS.
  • Initial pH of the pretreatment step of examples 4, C5, C6 and C7 were respectively 9,0, 7,0, 6,0 and 5,0.
  • the pH was measured with the standard laboratory glass electrode described above. The pH was not measured nor adjusted after the addition of the chelating agent, until the end of the pretreatment step.
  • the washing step was carried out as in Examples 1, C2 and C3.
  • the bleaching step was carried out at 70 0 C, during 120 minutes, at a consistency of 15 % by weight of dry pulp, with a bleach liquor containing 3 % hydrogen peroxide, 2.08 % NaOH, and 2 % sodium silicate by weight of dry pulp.
  • a mechanical paper pulp (PGW) with an initial brightness of 65,6 0 ISO was pretreated with EDDS, washed as per the process in Examples 1, C2 and C3, then submitted to a bleaching process with hydrogen peroxide.
  • the pretreatment step was carried out at 60 0 C, during 20 minutes, at a consistency of 10 % by weight of dry pulp and with a concentration of 0.5 % in EDDS.
  • Initial pH of the pretreatment step of examples 8, 9, ClO and CI l were respectively 10,9, 9,5, 6,9 and 5,1.
  • the pH was measured with the standard laboratory glass electrode described above. The pH was not measured nor adjusted after the addition of the chelating agent, until the end of the pretreatment step.
  • the washing step was carried out as in Examples 1, C2 and C3.
  • the bleaching step was carried out at 70 0 C, during 120 minutes, at a consistency of 15 % by weight of dry pulp, with a bleaching liquor containing 3 % hydrogen peroxide, 1.8 % NaOH, and 1,5 % sodium silicate by weight of dry pulp.
  • the final pH is the pH of the reacting medium at the end of the pretreatment step.
  • Example 12 to 16 (according to the invention)
  • a mechanical paper pulp (PGW) with an initial brightness of 67,0 0 ISO was pretreated with IDS, washed as per the process in Examples 1, C2 and C3, then submitted to a bleaching process with hydrogen peroxide.
  • the pretreatment step was carried out at 60 0 C, during 20 minutes, at a consistency of 10 % by weight of dry pulp and with a concentration of 0.5 % in IDS.
  • Initial pH of the pretreatment step of examples 17, 18, C19 and C20 were respectively 11,0, 9,0, 7,1 and 5,1.
  • the pH was measured with the standard laboratory glass electrode described above. The pH was not measured nor adjusted after the addition of the chelating agent, until the end of the pretreatment step.
  • the washing step was carried out as in Examples 1, C2 and C3.
  • the bleaching step was carried out at 70 0 C, during 120 minutes, at a consistency of 15 % by weight of dry pulp, with a bleaching liquor containing 3 % hydrogen peroxide, 1.8 % NaOH, and 1,5 % sodium silicate by weight of dry pulp.
  • the final pH is the pH of the reacting medium at the end of the pretreatment step.

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

Abstract

L'invention concerne un procédé pour le blanchiment de pâte à papier mécanique avec un ou plusieurs agents oxydants de type peroxydes, consistant à traiter préalablement la pâte dans une étape de prétraitement avec un ou plusieurs agents chélatants choisis parmi l'acide aspartique et ses dérivés, substitués sur l'atome d'azote, caractérisé en ce que le pH initial de l'étape de prétraitement, juste avant d'ajouter ledit ou lesdits agents chélatants, est supérieur à 8.
PCT/EP2007/050578 2006-01-24 2007-01-22 Procédé pour le blanchiment de pâte à papier mécanique WO2007085579A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP07704046.7A EP1979533B1 (fr) 2006-01-24 2007-01-22 Procédé pour le blanchiment de pâte à papier mécanique
US12/160,805 US20100163193A1 (en) 2006-01-24 2007-01-22 Process for the bleaching of mechanical paper pulp
CA2636355A CA2636355C (fr) 2006-01-24 2007-01-22 Procede pour le blanchiment de pate a papier mecanique

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06075155.9 2006-01-24
EP06075155A EP1811080A1 (fr) 2006-01-24 2006-01-24 Procédé de blanchiment de pate de papier mecanique

Publications (1)

Publication Number Publication Date
WO2007085579A1 true WO2007085579A1 (fr) 2007-08-02

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ID=36568695

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2007/050578 WO2007085579A1 (fr) 2006-01-24 2007-01-22 Procédé pour le blanchiment de pâte à papier mécanique

Country Status (5)

Country Link
US (1) US20100163193A1 (fr)
EP (2) EP1811080A1 (fr)
CA (1) CA2636355C (fr)
PL (1) PL1979533T3 (fr)
WO (1) WO2007085579A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011503369A (ja) * 2007-11-02 2011-01-27 インノスペック リミテッド パルプの漂白方法
US8361571B2 (en) 2008-06-20 2013-01-29 International Paper Company Composition and recording sheet with improved optical properties
US8801962B2 (en) 2009-01-26 2014-08-12 Innospec Limited Chelating agents and methods relating thereto

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7967948B2 (en) 2006-06-02 2011-06-28 International Paper Company Process for non-chlorine oxidative bleaching of mechanical pulp in the presence of optical brightening agents
EP2113044A1 (fr) * 2007-02-21 2009-11-04 SOLVAY (Société Anonyme) Procédé de blanchiment de pulpe de papier
BRPI1016066A2 (pt) * 2009-05-29 2016-06-07 Solvay "processo para o alvejamento de polpa de papel com um ou mais agentes oxidantes de peróxido, e, uso de componente"

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994003553A1 (fr) * 1992-08-01 1994-02-17 The Procter & Gamble Company Composition de blanchiment peroxy stabilisee a l'acide ethylenediamine-n,n'-disuccinique
WO1997030209A1 (fr) * 1996-02-19 1997-08-21 Kemira Chemicals Oy Procede de blanchiment de pate haut rendement
WO1997045586A1 (fr) * 1996-05-30 1997-12-04 Kemira Chemicals Oy Procede de blanchiment de pate a papier chimique
WO1999027178A1 (fr) * 1997-11-25 1999-06-03 Amylum Belgium N.V. Perfectionnements apportes au procede de blanchiment de la pate chimique et dispersions intermediaires de pate
WO1999046441A1 (fr) * 1998-03-10 1999-09-16 Solvay (Societe Anonyme) Procede de blanchiment et/ou de delignification de pates a papier
US6207010B1 (en) * 1997-04-04 2001-03-27 Bayer Aktiengesellschaft Preparation and use of iminodisuccinic acid salts
WO2005108673A1 (fr) * 2004-05-12 2005-11-17 Kemira Oyj Composition et procede pour le traitement d'une matiere fibreuse

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4388148A (en) * 1981-06-23 1983-06-14 Nalco Chemical Company Process for producing pulp
FI105701B (fi) * 1995-10-20 2000-09-29 Ahlstrom Machinery Oy Menetelmä ja laitteisto massan käsittelemiseksi
EP1826219A1 (fr) * 2006-02-24 2007-08-29 SOLVAY (Société Anonyme) Procédé de fabrication d'amidon oxydé, amidon oxydé et son utilisation
EP2113044A1 (fr) * 2007-02-21 2009-11-04 SOLVAY (Société Anonyme) Procédé de blanchiment de pulpe de papier

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994003553A1 (fr) * 1992-08-01 1994-02-17 The Procter & Gamble Company Composition de blanchiment peroxy stabilisee a l'acide ethylenediamine-n,n'-disuccinique
WO1997030209A1 (fr) * 1996-02-19 1997-08-21 Kemira Chemicals Oy Procede de blanchiment de pate haut rendement
WO1997045586A1 (fr) * 1996-05-30 1997-12-04 Kemira Chemicals Oy Procede de blanchiment de pate a papier chimique
US6207010B1 (en) * 1997-04-04 2001-03-27 Bayer Aktiengesellschaft Preparation and use of iminodisuccinic acid salts
WO1999027178A1 (fr) * 1997-11-25 1999-06-03 Amylum Belgium N.V. Perfectionnements apportes au procede de blanchiment de la pate chimique et dispersions intermediaires de pate
WO1999046441A1 (fr) * 1998-03-10 1999-09-16 Solvay (Societe Anonyme) Procede de blanchiment et/ou de delignification de pates a papier
WO2005108673A1 (fr) * 2004-05-12 2005-11-17 Kemira Oyj Composition et procede pour le traitement d'une matiere fibreuse

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011503369A (ja) * 2007-11-02 2011-01-27 インノスペック リミテッド パルプの漂白方法
AU2008320611B2 (en) * 2007-11-02 2013-11-28 Innospec Limited Process for bleaching pulp
US8906199B2 (en) 2007-11-02 2014-12-09 Innospec Limited Process for bleaching pulp
US8361571B2 (en) 2008-06-20 2013-01-29 International Paper Company Composition and recording sheet with improved optical properties
US8906476B2 (en) 2008-06-20 2014-12-09 International Paper Company Composition and recording sheet with improved optical properties
US9745700B2 (en) 2008-06-20 2017-08-29 International Paper Company Composition and recording sheet with improved optical properties
US8801962B2 (en) 2009-01-26 2014-08-12 Innospec Limited Chelating agents and methods relating thereto

Also Published As

Publication number Publication date
CA2636355C (fr) 2015-09-29
EP1811080A1 (fr) 2007-07-25
CA2636355A1 (fr) 2007-08-02
PL1979533T3 (pl) 2016-10-31
EP1979533B1 (fr) 2016-03-30
US20100163193A1 (en) 2010-07-01
EP1979533A1 (fr) 2008-10-15

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