EP0543175A1 - Procédé pour améliorer la blancheur dans le blanchiment au peroxyde de pâtes à papier par l'addition de cyanates - Google Patents

Procédé pour améliorer la blancheur dans le blanchiment au peroxyde de pâtes à papier par l'addition de cyanates Download PDF

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Publication number
EP0543175A1
EP0543175A1 EP92118163A EP92118163A EP0543175A1 EP 0543175 A1 EP0543175 A1 EP 0543175A1 EP 92118163 A EP92118163 A EP 92118163A EP 92118163 A EP92118163 A EP 92118163A EP 0543175 A1 EP0543175 A1 EP 0543175A1
Authority
EP
European Patent Office
Prior art keywords
bleaching
peroxide
whiteness
pulps
improving
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP92118163A
Other languages
German (de)
English (en)
Inventor
Harald Dr. Jakob
Hans Ulrich Dr. Süss
Norbert Dr. Nimmerfroh
Herbert Dr. Klenk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evonik Operations GmbH
Original Assignee
Degussa GmbH
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 Degussa GmbH filed Critical Degussa GmbH
Publication of EP0543175A1 publication Critical patent/EP0543175A1/fr
Withdrawn legal-status Critical Current

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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
    • D21C9/1026—Other features in bleaching processes
    • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes

Definitions

  • the invention relates to a method for improving the white content in the peroxide bleaching of cellulose by adding cyanates.
  • Dispensing with the use of chlorine-containing bleaching agents has led to a change in the whiteness level in the pulp bleaching.
  • the white levels used to be 88 to 90% ISO today bleaching using only oxygen and hydrogen peroxide is usually only 83 to 85% ISO for softwood pulps and 85 to 87% ISO for hardwood pulps. This lower whiteness can be partially tolerated because the pulps bleached with hydrogen peroxide have a significantly lower tendency to yellowing during thermal aging. In principle, however, it would still be desirable to achieve the whiteness level of chlorine bleach even with chlorine-free bleaching processes.
  • the invention relates to a process for improving the whiteness of pre-bleached and pre-bleached cellulose with oxygen, peroxide (hydrogen peroxide) and / or ozone, which is characterized in that an alkali metal cyanate is added in a further bleaching step with hydrogen peroxide.
  • Pre-bleached or pre-delignified means that the pulp has previously passed generally known bleaching sequences and extraction stages using oxygen, peroxide and / or ozone or their combinations.
  • the kappa value of the pulps to be bleached is between 2 and 15, in particular 2 and 10, their white content generally between 60 and 75% ISO (for beech pulp) and 40 .. to 50% ISO (for spruce pulp, kraft pulp).
  • the process conditions for the peroxide bleaching stage according to the invention correspond to the known conditions for bleaching stages of this type:
  • the pH is generally between 10 and 12, the consistency is between 5 and 30% by weight, preferably 10 to 25% by weight.
  • the bleaching temperature is between 40 ° C and 90 ° C, preferably 50 ° C and 80 ° C, depending on the type of pulp to be bleached.
  • the amount of alkali metal cyanate used is 5 to 50% by weight, preferably 15 to 40% by weight, of the amount of hydrogen peroxide used, of which 0.5 to 5.0% by weight is used, in particular 1.5 up to 3.0% by weight, based on dry cellulose.
  • the process is suitable for pulp from conifers and hardwoods as well as annual plants, produced by the kraft pulp process, the acidic or alkaline sulfite process, optionally in the presence of alcohols (methanol, ethanol).

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
EP92118163A 1991-11-19 1992-10-23 Procédé pour améliorer la blancheur dans le blanchiment au peroxyde de pâtes à papier par l'addition de cyanates Withdrawn EP0543175A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19914138006 DE4138006A1 (de) 1991-11-19 1991-11-19 Verfahren zur verbesserung des weissgehaltes bei der peroxidbleiche von zellstoffen durch den zusatz von cyanaten
DE4138006 1991-11-19

Publications (1)

Publication Number Publication Date
EP0543175A1 true EP0543175A1 (fr) 1993-05-26

Family

ID=6445118

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92118163A Withdrawn EP0543175A1 (fr) 1991-11-19 1992-10-23 Procédé pour améliorer la blancheur dans le blanchiment au peroxyde de pâtes à papier par l'addition de cyanates

Country Status (4)

Country Link
EP (1) EP0543175A1 (fr)
CA (1) CA2083319A1 (fr)
DE (1) DE4138006A1 (fr)
FI (1) FI925146A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002016538A1 (fr) * 2000-08-18 2002-02-28 The University Of Leeds Utilisation d'acides percarbamiques et de diacyl percarbamates et de leurs precurseurs

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2175621A (en) * 1985-05-28 1986-12-03 Lion Corp Bleaching compositions
EP0442425A1 (fr) * 1990-02-13 1991-08-21 SKW Trostberg Aktiengesellschaft Procédé pour le blanchiment et la délignification exempt de chlore de pâtes cellulosiques

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2175621A (en) * 1985-05-28 1986-12-03 Lion Corp Bleaching compositions
EP0442425A1 (fr) * 1990-02-13 1991-08-21 SKW Trostberg Aktiengesellschaft Procédé pour le blanchiment et la délignification exempt de chlore de pâtes cellulosiques

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002016538A1 (fr) * 2000-08-18 2002-02-28 The University Of Leeds Utilisation d'acides percarbamiques et de diacyl percarbamates et de leurs precurseurs
US7159333B2 (en) 2000-08-18 2007-01-09 The University Of Leeds Use of percarbamic acids and diacyl percarbamates and precursors therefor

Also Published As

Publication number Publication date
DE4138006A1 (de) 1993-05-27
CA2083319A1 (fr) 1993-05-20
FI925146A0 (fi) 1992-11-12
FI925146A (fi) 1993-05-20

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Effective date: 19940727