EP0679760B1 - Verfahren zum Bleichen von Lignocellulose-enthaltendem Zellstoff - Google Patents

Verfahren zum Bleichen von Lignocellulose-enthaltendem Zellstoff Download PDF

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Publication number
EP0679760B1
EP0679760B1 EP94203640A EP94203640A EP0679760B1 EP 0679760 B1 EP0679760 B1 EP 0679760B1 EP 94203640 A EP94203640 A EP 94203640A EP 94203640 A EP94203640 A EP 94203640A EP 0679760 B1 EP0679760 B1 EP 0679760B1
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EP
European Patent Office
Prior art keywords
pulp
magnesium
calcium
compound
chlorine
Prior art date
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Expired - Lifetime
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EP94203640A
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English (en)
French (fr)
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EP0679760A1 (de
Inventor
Lennart Andersson
Jiri Basta
Lillemor Holtinger
Jan Höök
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Nouryon Pulp and Performance Chemicals AB
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Eka Chemicals AB
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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
    • D21C9/16—Bleaching ; Apparatus therefor with per compounds
    • D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
    • 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
    • D21C9/1026—Other features in bleaching processes
    • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
    • 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
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone

Definitions

  • the present invention relates to a process for delignification and bleaching of chemically digested lignocellulose-containing pulp, wherein the pulp is acid treated at a pH of between about 1 and about 6, whereupon a water-soluble mixture of a magnesium compound and a calcium compound is added at a pH of between about 1 and about 7 before the pulp is treated with a chlorine-free bleaching agent comprising hydrogen peroxide at a pH of from about 8 up to about 12.
  • the initial acidic treatment removes the trace metals of the pulp, whereas the subsequent addition of alkaline earth metal ions in aqueous solution returns the ions to the positions in the pulp where they have a particularly beneficial effect on the preservation of the cellulose chains and, consequently, on the viscosity, as well as on the consumption of bleaching agent in the subsequent bleaching step.
  • the pulp may be finally bleached to the desired brightness, suitably with a chlorine-free bleaching agent, such a ozone, to completely avoid formation and discharge of AOX.
  • chlorine-free bleaching agents such as hydrogen peroxide, peracetic acid or ozone
  • the delignification and consumption of the bleaching agent become less effective than with chlorine-containing bleaching agents, unless the pulp is pretreated.
  • a hydrogen peroxide treatment in an alkaline environment is disturbed by the presence in the pulp of ions of certain metals, such as Mn, Cu and Fe. These metal ions cause degradation of hydrogen peroxide, thereby reducing the efficiency of the peroxide treatment and increasing the consumption of peroxide.
  • this can be counteracted by pretreating the pulp with an acid, such as sulphuric acid or nitric acid, whereby the concentration of all types of metal ions is reduced.
  • an acid such as sulphuric acid or nitric acid
  • metal ions for example Mg, which are advantageous to the peroxide treatment disappear, which ions stabilize the peroxide and increase the selectivity of the peroxide.
  • CA-A-575,636 discloses the addition of magnesium sulphate to stabilize alkaline peroxide solutions. However, the addition is made directly to the bleaching liquor and in alkaline environment insoluble magnesium hydroxide precipitates.
  • EP-A-0 148 712 teaches to bleach chemical cellulose pulp with hydrogen peroxide in one step at a pH of 11 to 11,5.
  • the peroxide bleach solution comprises a salt of magnesium and a salt of calcium which are kept in solution by means of a complexing agent.
  • US-A-4,222,819 discloses the addition of magnesium ions to acidic peroxide solutions, but also in this case the addition is made directly to the bleaching liquor. None of the related methods makes possible diffusion of the magnesium ions into the pulp to such an extent, that a pulp of high brightness and strength can be obtained.
  • the invention provides a process in which lignocellulose-containing pulp is treated under the conditions disclosed in the claims, whereby the metal ions harmful to the subsequent bleaching are effectively removed and the profile of alkaline earth metals is restored before the pulp is bleached in a chlorine-free bleaching step.
  • the invention relates to a process for bleaching of chemically digested lignocellulose-containing pulp, wherein the pulp is acid treated at a pH in the range from about 1 up to about 6, whereupon the pulp is washed and a mixture containing a magnesium compound and a calcium compound is added at a pH in the range from about 1 up to about 7 and in an amount of from about 0.01 kg, suitably 0.5 kg, up to about 10 kg/ton of dry pulp, calculated as magnesium and calcium, and that the pulp subsequently is treated with a chlorine-free bleaching agent comprising hydrogen peroxide at a pH of from about 8 up to about 12.
  • Acid treatment is an effective process to eliminate metal ions from lignocellulose-containing pulps.
  • ions of magnesium and calcium especially when in their original positions in the pulp, have a positive influence on the selectivity of the delignification as well as on the stability and consumption of chlorine-free bleaching agents, such as peroxides, ozone and oxygen.
  • the present process presents an economic solution to the problem of creating a suitable trace-metal profile for the subsequent chlorine-free bleaching, in that non-desirable metal ions are eliminated while supplied ions of magnesium and calcium essentially recover the positions in the vicinity of the cellulose chains previously occupied by ions of alkaline earth metals.
  • an advantage of the present process is that the pH adjustment between the treatment with acid and addition of alkaline earth metal ions becomes very limited or may be left out altogether, which is advantageous to process technique and economy.
  • Chlorine-free bleaching agents include inorganic peroxide compounds, such as hydrogen peroxide and sodium peroxide, organic peroxide compounds, such as peracetic acid, as well as ozone, oxygen and sodium dithionite.
  • hydrogen peroxide (P), oxygen (O) and ozone (Z) are used in an optional sequence or mixture.
  • the sequence P-Z or (PO)-Z are especially preferred.
  • pH is suitably adjusted by adding to the pulp an alkali or an alkali-containing liquid, such as sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, oxidized white liquor or magnesium hydroxide slurry.
  • an alkali or an alkali-containing liquid such as sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, oxidized white liquor or magnesium hydroxide slurry.
  • the magnesium hydroxide slurry is taken from the chemical handling system in the production of sulphite pulp with magnesium as base, i.e. magnefite pulp.
  • the acid treatment suitably is carried out with an acid.
  • the acids used are inorganic acids, suitably sulphuric acid, nitric acid, hydrochloric acid or residual acid from a chlorine dioxide reactor, either separately or in an optional mixture.
  • sulphuric acid is employed.
  • magnesium-containing compounds such as magnesium sulphate or magnesium chloride
  • calcium-containing compounds such as calcium chloride or calcium oxide.
  • the acid treatment is carried out at a pH of from about 1 up to about 6, suitably from 1.5 up to 5, preferably from 2 up to 4. It is especially preferred that the acid treatment is carried out at a pH of from 2 up to 3.
  • Magnesium is one of the alkaline earth metals in the compounds containing an alkaline earth metal.
  • the addition is made at a pH in the range from about 1 up to about 7, suitably in the range from 2 up to 6, preferably in the range from 2 up to 4. It is especially preferred that the addition of magnesium is made at a pH of from 2 up to 3.
  • the chlorine-free bleaching agent is hydrogen peroxide
  • the pulp is treated at a pH of from about 8 up to about 12, preferably at a pH of from 10 up to 12. Treatment with the other chlorine-free bleaching agents mentioned above, is carried out within the same pH range.
  • the treatment according to the invention is carried out with a washing step between the acid treatment and addition of alkaline earth metal ions, such that the trace metals that are harmful to the treatment with a chlorine-free bleaching agent are removed from the pulp suspension.
  • a mixture of a magnesium compound and a calcium compound and a chlorine-free bleaching agent can be carried out at an optional position in the bleaching sequence, e.g. immediately after digestion of the pulp or after an oxygen step.
  • the process according to the invention is preferably applied to pulp that has been delignified in an oxygen step prior to the treatment.
  • the pulp in the acid treatment also can be subjected to bleaching and/or delignifying treatment.
  • Bleaching and/or delignifying chemicals active within the pH range suitable in the acid treatment are e.g. chlorine dioxide, ozone, peracetic acid and/or an acid peroxide-containing compound.
  • a combination of acid treatment and bleaching and/or delignifying treatment takes place in an ozone step.
  • Lignocellulose-containing pulps relate to chemical pulps of softwood and/or hardwood digested according to the sulphite, sulphate, soda or organosolv process, or modifications and/or combinations thereof.
  • Use is suitably made of softwood and/or hardwood digested according to the sulphate process, preferably sulphate pulp of hardwood.
  • the treatment according to the invention can be applied to lignocellulose-containing pulps having an initial kappa number within the range from about 5 up to about 40, suitably 7 up to 32, preferably from 10 up to 20.
  • the kappa number is determined according to the standard method SCAN-C 1:77.
  • the acid treatment is carried out at a temperature of from about 10 up to about 95°C, suitably from 20 up to 80°C and preferably from 40 up to 80°C, and for a period of time of from about 1 up to about 120 min, suitably from 10 up to 120 min and preferably from 20 up to 40 min.
  • the mixture of a magnesium compound and a calcium compound is added at a temperature of from about 10 up to about 95°C, preferably from 40 up to 80°C, and for a period of time of from about 1 up to about 180 min, preferably from 20 up to 180 min and preferably from 30 up to 120 min.
  • the pulp is treated at a temperature of from about 30 up to about 100°C, preferably from 60 up to 90°C, and for a period of time of from about 30 up to about 300 min, suitably from 60 up to 240 min.
  • the pulp concentration may be from about 3 up to about 35% by weight, preferably from 3 up to 15% by weight.
  • the pulp concentration may be from about 3 up to about 50% by weight, suitably from 3 up to 35% by weight and preferably from 10 up to 25% by weight.
  • Treatment with the other chlorine-free bleaching agents mentioned above is carried out within the normal ranges of temperature, time and pulp concentration for each bleaching agent, which are well-known to the person skilled in the art.
  • the amount of mixture containing a magnesium compound and a calcium compound charged lies in the range from about 0.5 up to about 10 kg/ton of dry pulp, suitably in the range from 0.5 up to 5 kg/ton of dry pulp, and preferably in the range from 2 up to 4 kg/ton of dry pulp, calculated as magnesium and calcium.
  • the amount of hydrogen peroxide lies in the range from about 2 up to about 50 kg/ton of dry pulp, calculated as 100% hydrogen peroxide.
  • the upper limit is not critical, but has been set for reasons of economy.
  • the amount of hydrogen peroxide suitably lies in the range from 3 up to 30 kg/ton of dry pulp and preferably from 4 up to 20 kg/ton of dry pulp, calculated as 100% hydrogen peroxide.
  • the pulp can be used for direct production of paper with a lower demand of brightness.
  • the pulp may be finally bleached to the desired higher brightness, by treatment in one or more steps.
  • the final bleaching is also carried out with chlorine-free bleaching agents of the type mentioned above, optionally with intermediate alkaline extraction steps, which may be reinforced with peroxide and/or oxygen. In this way, the formation and discharge of AOX is completely eliminated.
  • the final bleaching is carried out with ozone in one or more steps.
  • the lignin content has been reduced to a sufficiently low level before any chlorine-containing bleaching agents are used. Therefore, chlorine dioxide and/or hypochlorite may well be used in one or more final bleaching steps without causing formation of large amounts of AOX.
  • the process according to the invention means that the brightness and kappa number of the resulting pulp is higher and lower, respectively, than with the processes in which a mixture of a magnesium compound and a calcium compound is not added at all or is added at a higher pH.
  • the aim is a high brightness as well as a low kappa number, the latter meaning a low content of undissolved lignin.
  • the consumption of the chlorine-free bleaching agent should be as low as possible meaning lower treatment costs.
  • these objects are met.
  • the strength of the pulp measured as viscosity, is sufficient, which means that the pulp contains cellulose chains which are long enough to give a strong product.
  • Sulphate pulp of softwood having a kappa number of 17, a brightness of 35% ISO and a viscosity of 970 dm 3 /kg was treated with sulphuric acid at a pH of 2.0.
  • the pulp was treated at a temperature of 60°C for 30 min, the pulp concentration being 10% by weight.
  • magnesium was added in the form of an aqueous solution containing MgSO 4 , to give a concentration of magnesium in the pulp of at least 500 ppm.
  • the pH at the time of the addition was varied between 2.3 and 11.5 by addition of sulphuric acid.
  • the pulp was bleached with hydrogen peroxide at a temperature of 90°C, the residence time and pulp concentration being 180 min and 15% by weight, respectively.
  • the final pH was 11.5, and the addition of hydrogen peroxide was 15 kg/ton of dry pulp, calculated as 100% hydrogen peroxide.
  • magnesium was added directly to the hydrogen peroxide step under the conditions stated above, in accordance with the prior art.
  • the pulp was also treated with only sulphuric acid and hydrogen peroxide under the conditions stated above.
  • the kappa number, viscosity and brightness of the pulp were determined according to SCAN Standard Methods, and the consumption of hydrogen peroxide was determined by iodometric titration. The test results appear from the Table below.
  • the treatment with MgSO 4 at a pH in the range from about 2 up to about 6 is essential to give maximum increase in brightness and maximum reduction of the kappa number, as well as minimum decrease in viscosity and minimum consumption of hydrogen peroxide. Furthermore, the importance of the magnesium ions for the increase in brightness appears from the comparison at a pH of 2.3, where, in the final test, the peroxide treatment was preceded only by acidic treatment.

Claims (9)

  1. Verfahren zum Entholzen und Bleichen von chemisch aufgeschlossenem lignocellulosehaltigem Zellstoff, in dem der Zellstoff bei einem pH-Wert im Bereich von etwa 1 bis etwa 6 mit Säure behandelt wird und der Zellstoff nach der Säurebehandlung gewaschen wird, dadurch gekennzeichnet, daß danach ein wasserlösliches Gemisch einer Magnesiumverbindung und einer Calciumverbindung bei einem pH-Wert im Bereich von etwa 1 bis etwa 7 und in einer Menge von etwa 0.5 bis etwa 10 kg/Tonne des trockenen Zellstoffs, berechnet als Magnesium und Calcium, zugegeben wird, und daß der Zellstoff anschließend mit einem chlorfreien Bleichmittel, umfassend Wasserstoffperoxid, bei einem pH-Wert von etwa S bis etwa 12 entholzt und gebleicht wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das wasserlösliche Gemisch einer Magnesiumverbindung und einer Calciumverbindung in einer Menge von etwa 2 bis etwa 10 kg/Tonne des trockenen Zellstoffs, berechnet als Magnesium und Calcium, zugegeben wird.
  3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der chemisch aufgeschlossene Zellstoff Sulfatzellstoff ist.
  4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das wasserlösliche Gemisch einer Magnesiumverbindung und einer Calciumverbindung bei einem pH-Wert von 2 bis 6 zugegeben wird.
  5. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Calciumverbindung Calciumchlorid oder Calciumoxid ist.
  6. Verfahren nach Anspruch 1 oder 5, dadurch gekennzeichnet, daß die Magnesiumverbindung Magnesiumsulfat oder Magnesiumchlorid ist.
  7. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das chlorfreie Bleichmittel aus Sauerstoff und Wasserstoffperoxid besteht.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß der Zellstoff nach der Behandlung schließlich in einem oder mehreren Schritten mit Ozon gebleicht wird.
  9. Verfahren nach den Ansprüchen 1-8, dadurch gekennzeichnet, daß die Säurebehandlung bei einer Temperatur von etwa 10 bis etwa 95°C während etwa 1 bis etwa 120 Min. durchgeführt wird, daß das Gemisch einer Magnesiumverbindung und einer Calciumverbindung bei einer Temperatur von etwa 10 bis etwa 95°C während etwa 1 bis etwa 180 Min. und in einer Menge von 0.5 bis 5 kg/Tonne des trockenen Zellstoffs. berechnet als Magnesiumverbindung und Calciumverbindung, zugegeben wird, wobei der behandelte Zellstoff eine Konzentration von etwa 3 bis etwa 35 Gew.-% hat, und daß der Zellstoff bei einem pH-Wert von etwa 8 bis etwa 12 mit Wasserstoffperoxid gebleicht und entholzt wird.
EP94203640A 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose-enthaltendem Zellstoff Expired - Lifetime EP0679760B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9101301A SE470065C (sv) 1991-04-30 1991-04-30 Behandling av kemisk massa med en syra och därefter en magnesium- och kalciumförening vid klorfri blekning
SE9101301 1991-04-30
EP92201005A EP0511695B2 (de) 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose enthaltendem Zellstoff

Related Parent Applications (2)

Application Number Title Priority Date Filing Date
EP92201005A Division EP0511695B2 (de) 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose enthaltendem Zellstoff
EP92201005.3 Division 1992-04-08

Publications (2)

Publication Number Publication Date
EP0679760A1 EP0679760A1 (de) 1995-11-02
EP0679760B1 true EP0679760B1 (de) 1998-11-18

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ID=20382601

Family Applications (2)

Application Number Title Priority Date Filing Date
EP94203640A Expired - Lifetime EP0679760B1 (de) 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose-enthaltendem Zellstoff
EP92201005A Expired - Lifetime EP0511695B2 (de) 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose enthaltendem Zellstoff

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP92201005A Expired - Lifetime EP0511695B2 (de) 1991-04-30 1992-04-08 Verfahren zum Bleichen von Lignocellulose enthaltendem Zellstoff

Country Status (14)

Country Link
EP (2) EP0679760B1 (de)
JP (1) JP2592747B2 (de)
AT (2) ATE173518T1 (de)
BR (1) BR9201554A (de)
CA (1) CA2067296C (de)
DE (2) DE69227640T2 (de)
ES (1) ES2091395T3 (de)
FI (1) FI111964B (de)
MX (1) MX9201966A (de)
NO (1) NO180495C (de)
NZ (1) NZ242465A (de)
RU (1) RU2039141C1 (de)
SE (1) SE470065C (de)
ZA (1) ZA923073B (de)

Families Citing this family (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI89516B (fi) 1989-05-10 1993-06-30 Ahlstroem Oy Foerfarande foer blekning av cellulosamassa med otson
US6398908B1 (en) 1991-04-30 2002-06-04 Eka Nobel Ab Process for acid bleaching of lignocellulose-containing pulp with a magnesium compound
SE500353C2 (sv) * 1992-10-26 1994-06-06 Sca Wifsta Oestrand Ab Peroxidblekning av sulfatmassa med tillsats av magnesium före blekningen
SE512137C2 (sv) * 1992-10-29 2000-01-31 Eka Chemicals Ab Förfarande för blekning av lignocellulosahaltig massa
SE9203366L (sv) * 1992-11-11 1994-05-12 Mo Och Domsjoe Ab Förfarande vid delignifiering och/eller blekning av cellulosamassa
US6007678A (en) * 1992-11-27 1999-12-28 Eka Nobel Ab Process for delignification of lignocellulose-containing pulp with an organic peracid or salts thereof
EP0622491B2 (de) * 1993-04-20 2002-07-17 Eka Chemicals AB Verfahren zum Bleichen von Lignozellulose-enthaltendem Zellstoff
SE500616C2 (sv) * 1993-06-08 1994-07-25 Kvaerner Pulping Tech Blekning av kemisk massa med peroxid vid övertryck
US6605181B1 (en) * 1993-10-01 2003-08-12 Kvaerner Pulping Aktiebolag Peroxide bleach sequence including an acidic bleach stage and including a wash stage
BE1007757A3 (fr) * 1993-11-10 1995-10-17 Solvay Interox Procede pour le blanchiment d'une pate a papier chimique.
FI102301B1 (fi) * 1994-10-13 1998-11-13 Ahlstrom Machinery Oy Menetelmä selluloosamassojen käsittelemiseksi
US6776876B1 (en) 1994-10-13 2004-08-17 Andritz Oy Method of treating cellulosic pulp to remove hexenuronic acid
DE19516151A1 (de) 1995-05-03 1996-11-07 Sven Siegle Verfahren zur Herstellung einer Pulpe aus zellulosehaltigem Material, die Pulpe selbst und deren Verwendung
FI105701B (fi) 1995-10-20 2000-09-29 Ahlstrom Machinery Oy Menetelmä ja laitteisto massan käsittelemiseksi
JPH108092A (ja) * 1996-06-21 1998-01-13 Mitsubishi Paper Mills Ltd 過酸化物漂白用安定化剤及びそれを用いた繊維系物質の漂白方法
BE1010679A3 (fr) * 1996-10-11 1998-11-03 Solvay Interox Procede de delignification et de blanchiment de pate a papier chimique.
ID23571A (id) * 1997-08-25 2000-05-04 Praxair Technology Inc Metoda penerapan ozon dalam pemutihan ecf
JP2002266272A (ja) * 2001-03-12 2002-09-18 Nippon Paper Industries Co Ltd セルロース質繊維材料パルプの漂白方法
US6743332B2 (en) * 2001-05-16 2004-06-01 Weyerhaeuser Company High temperature peroxide bleaching of mechanical pulps
KR100547491B1 (ko) * 2005-04-27 2006-01-31 이권혁 대나무를 이용하여 생산하는 섬유용 펄프의 제조방법 및 그 펄프
US9511167B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US8778136B2 (en) 2009-05-28 2014-07-15 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9512237B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Method for inhibiting the growth of microbes with a modified cellulose fiber
US9512563B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Surface treated modified cellulose from chemical kraft fiber and methods of making and using same
JP6254078B2 (ja) 2011-05-23 2017-12-27 ゲーペー ツェルローゼ ゲーエムベーハー 白色度および明度が改善された針葉樹クラフト繊維、ならびにそれを作製する方法および使用する方法
KR102093167B1 (ko) 2012-01-12 2020-03-26 게페 첼루로제 게엠베하 황변 성질이 감소된 저 점성 크래프트 섬유 및 그의 제조 및 사용 방법
RU2636306C2 (ru) 2012-04-18 2017-11-21 ДжиПи СЕЛЛЬЮЛОУС ГМБХ Использование поверхностно-активного вещества для обработки пульпы и улучшение введения крафт-пульпы в волокно для получения вискозы и других вторичных волокнистых продуктов
JP6129323B2 (ja) * 2012-09-27 2017-05-17 アンドリッツ インコーポレーテッド リグノセルロース系繊維束材料の化学的処理並びにそれに関する方法及びシステム
MX365675B (es) 2013-02-08 2019-06-10 Gp Cellulose Gmbh Fibra kraft de madera blanda que tiene un contenido mejorado de a-celulosa, y su uso en la produccion de productos de celulosa quimica.
WO2014140852A2 (en) 2013-03-14 2014-09-18 Gp Cellulose Gmbh A method of making highly functional, low viscosity kraft fiber using an acidic bleaching sequence and a fiber made by the process
BR112015020000A2 (pt) 2013-03-15 2017-07-18 Gp Cellulose Gmbh fibra kraft quimicamente modificada e métodos de fabricação da mesma
WO2017055504A1 (en) * 2015-09-30 2017-04-06 Imerys Minerals Limited Methods for bleaching aqueous pulps and compositions for use in these methods
CA3040734A1 (en) 2016-11-16 2018-05-24 Gp Cellulose Gmbh Modified cellulose from chemical fiber and methods of making and using the same
WO2021209586A1 (en) * 2020-04-16 2021-10-21 Bim Kemi Ab Delignification process

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1206704A (fr) * 1982-01-28 1986-07-02 Dominique Lachenal Procede pour le traitement de pates papetieres chimiques

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3507744A (en) * 1966-04-01 1970-04-21 Kimberly Clark Co Wood pulp bleaching process utilizing peroxide pyrophosphate high concentration compositions
SE335053B (de) * 1969-05-13 1971-05-10 Mo Och Domsjoe Ab
DE2742262C2 (de) * 1977-09-20 1982-06-09 Degussa Ag, 6000 Frankfurt Verfahren zur Herstellung eines mittel- bis hochviskosen Nadelholz-Sulfitzellstoffs
FR2557605B1 (fr) * 1983-12-29 1987-12-11 Atochem Procede de blanchiment de pates papetieres par le peroxyde d'hydrogene
JPH0364589A (ja) * 1989-07-28 1991-03-19 Mitsubishi Gas Chem Co Inc 化学パルプの漂白方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1206704A (fr) * 1982-01-28 1986-07-02 Dominique Lachenal Procede pour le traitement de pates papetieres chimiques

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
J.P. CASEY: "Pulp and Paper; Chemistry and Chemical Technology, 3rd edition, vol. I, page 651", JOHN WILEY & SONS, NEW YORK *

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SE470065C (sv) 1995-10-12
EP0511695B2 (de) 2004-06-02
FI921886A0 (fi) 1992-04-27
ATE173518T1 (de) 1998-12-15
RU2039141C1 (ru) 1995-07-09
ZA923073B (en) 1992-12-30
DE69227640T2 (de) 1999-05-06
ATE141971T1 (de) 1996-09-15
NO180495C (no) 2003-06-06
EP0511695A1 (de) 1992-11-04
EP0511695B1 (de) 1996-08-28
SE9101301L (sv) 1992-10-31
BR9201554A (pt) 1992-12-01
JP2592747B2 (ja) 1997-03-19
SE470065B (sv) 1993-11-01
FI921886A (fi) 1992-10-31
ES2091395T3 (es) 1996-11-01
SE9101301D0 (sv) 1991-04-30
DE69213080D1 (de) 1996-10-02
JPH05148784A (ja) 1993-06-15
MX9201966A (es) 1992-11-01
FI111964B (fi) 2003-10-15
NZ242465A (en) 1993-12-23
AU651192B2 (en) 1994-07-14
NO921671L (no) 1992-11-02
AU1514992A (en) 1993-03-11
CA2067296C (en) 1997-03-04
NO180495B (no) 1997-01-20
CA2067296A1 (en) 1992-10-31
EP0679760A1 (de) 1995-11-02
DE69227640D1 (de) 1998-12-24
NO921671D0 (no) 1992-04-29

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