EP0417411A1 - Process for stabilizing the viscosity of pulp - Google Patents

Process for stabilizing the viscosity of pulp Download PDF

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Publication number
EP0417411A1
EP0417411A1 EP90112190A EP90112190A EP0417411A1 EP 0417411 A1 EP0417411 A1 EP 0417411A1 EP 90112190 A EP90112190 A EP 90112190A EP 90112190 A EP90112190 A EP 90112190A EP 0417411 A1 EP0417411 A1 EP 0417411A1
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European Patent Office
Prior art keywords
viscosity
ozone
pulp
iso
strength
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.)
Ceased
Application number
EP90112190A
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German (de)
French (fr)
Inventor
Hans Ulrich Dr. Süss
Wilfried Dr. Eul
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Evonik Operations GmbH
Original Assignee
Degussa GmbH
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Publication date
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Publication of EP0417411A1 publication Critical patent/EP0417411A1/en
Ceased 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
    • D21C9/1026—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
    • D21C9/1026—Other features in bleaching processes
    • D21C9/1047—Conserving the bleached 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
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution

Definitions

  • ozone is a very reactive and at the same time non-selective bleaching agent, side reactions such as the oxidation of cellulose cannot be avoided even with small amounts of ozone.
  • the resulting carbonyl groups increase the sensitivity of cellulose to alkaline degradation.
  • the object of the invention is to find a process in which, in comparison to the bleached using chlorine at low ozone doses, there is practically no decrease in the viscosity and even at higher concentrations, only a slight decrease in tolerance and pulps with a white content of about 90 (ISO) receives.
  • the invention relates to a method for stabilizing the viscosity of pulp following an ozone or ozone / oxygen treatment, which is characterized in that the pulp at a pH of 8 to 12 with 0.05 to 1 wt. % Formamidine sulfinic acid, based on dry cellulose, at 40 to 90 ° C, preferably 50 to 80 ° C, treated.
  • Alkaline and acidic sulfite pulps and kraft pulp based on softwood and hardwood are suitable as pulp for this process.
  • the ozone or ozone / oxygen treatment is generally carried out in an acidic medium at an ozone concentration of 0.1 to 4%, based on absolutely dry cellulose.
  • the formamidine sulfinic acid is used in the subsequent alkaline extraction step without additional equipment.
  • the pulp is between 5 and 10%, preferably 8 and 12%,
  • the normal residence time in this stage is generally sufficient to stabilize the viscosity.

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

Abstract

Es wird ein Verfahren beschrieben, bei dem man durch den Zusatz von Formamidinsulfinsäure im Anschluß an eine Ozon- bzw. Ozon-/Sauerstoffbehandlung Viskosität und Festigkeit von Zellstoffen auf dem Niveau stabilisiert, das man unter Einsatz konventioneller, chlorhaltiger Bleichverfahren erreicht.A process is described in which the viscosity and strength of pulps are stabilized at the level which is achieved using conventional chlorine-containing bleaching processes by adding formamidine sulfinic acid following ozone or ozone / oxygen treatment.

Description

Zur Intensivierung der Delignifizierung ist die Kombination des Einsatzes von Sauerstoff und Ozon notwendig. Da Ozon ein sehr reaktives und gleichzeitig unselektives Bleichmittel darstellt, sind bereits bei geringenOzon-Einsatzmengen Nebenreaktionen, wie die Oxidation der Cellulose, nicht zu vermeiden.The combination of oxygen and ozone is necessary to intensify delignification. As ozone is a very reactive and at the same time non-selective bleaching agent, side reactions such as the oxidation of cellulose cannot be avoided even with small amounts of ozone.

Die dabei entstehenden Carbonylgrupen erhöhen die Empfindlichkeit der Zellulose gegen den alkalischen Abbau.The resulting carbonyl groups increase the sensitivity of cellulose to alkaline degradation.

Dieser führt bei der der Ozonbehandlung, die im sauren stattfindet, folgenden alkalischen Extraktion zu einer Aufspaltung der Zelluloseketten und damit im Vergleich zu den unter Chloreinsatz gebleichten Stoffen zu einem Rückgang der Viskosität und der Festigkeiten der Zellulose.
O. Kordsachia und R. Patt beschreiben in der Zeitschrift Holzforschung 42 (1988) 203-209, daß man durch den Zusatz von Natriumborhydrid das durch die Ozonbehandlung verursachte Absinken des durchschnittlichen Polymeri­sationswertes zumindest teilweise rückgängig machen kann.
Dies gelingt jedoch nur bei niedrigen Ozondosierungen (0,5 %) und bescheidenen Weißgehalten (86(ISO)).In the case of the alkaline extraction following the ozone treatment, which takes place in acid, this leads to a breakdown of the cellulose chains and thus to a decrease in the viscosity and strength of the cellulose compared to the bleached substances using chlorine.
O. Kordsachia and R. Patt describe in the journal Holzforschung 42 (1988) 203-209 that the addition of sodium borohydride can at least partially reverse the decrease in the average polymerization value caused by ozone treatment.
However, this is only possible with low ozone doses (0.5%) and modest whiteness levels (86 (ISO)).

Aufgabe der Erfindung ist es, ein Verfahren zu finden, bei dem man im Vergleich zu den unter Chloreinsatz gebleichten Stoffen bei niedrigen Ozondosierungen praktisch kein Absinken der Viskositäten und auch bei höheren Konzentrationen ein nur geringfügiges Nachlassen in Kauf nehmen muß und Zellstoffe mit einem Weißgehalt von etwa 90 (ISO) erhält.The object of the invention is to find a process in which, in comparison to the bleached using chlorine at low ozone doses, there is practically no decrease in the viscosity and even at higher concentrations, only a slight decrease in tolerance and pulps with a white content of about 90 (ISO) receives.

Gegenstand der Erfindung ist ein Verfahren zur Stabilisierung der Viskosität von Zellstoff im Anschlußan eine Ozon- bzw. Ozon-/Sauerstoffbehandlung, das dadurch gekennzeichnet ist, daß man den Zellstoff bei einempH-Wert von 8 bis 12 mit 0,05 bis 1 Gew.-% Formamidinsulfinsäure, bezogen auf atro Zellstoff, bei 40 bis 90 °C, bevorzugt 50 bis 80 °C, behandelt.The invention relates to a method for stabilizing the viscosity of pulp following an ozone or ozone / oxygen treatment, which is characterized in that the pulp at a pH of 8 to 12 with 0.05 to 1 wt. % Formamidine sulfinic acid, based on dry cellulose, at 40 to 90 ° C, preferably 50 to 80 ° C, treated.

Als Zellstoff sind für dieses Verfahren geeignet alkalisch und sauer erzeugte Sulfitzellstoffe sowie Kraftzellstoff jeweils auf Nadel- und Laubholzbasis.Alkaline and acidic sulfite pulps and kraft pulp based on softwood and hardwood are suitable as pulp for this process.

Die Ozon- bzw. Ozon-/Sauerstoffbehandlung erfolgt nach dem Stand der Technik im sauren Medium im allgemeinen bei einer Ozon-Konzentration von 0,1 bis 4 %, bezogena uf absolut trockenen Zellstoff. Die Formamidinsulfinsäure wird ohne zusätzlichen apparativen Aufwand in der sich daran anschließenden alkalischen Extraktionsstufe eingesetzt.According to the prior art, the ozone or ozone / oxygen treatment is generally carried out in an acidic medium at an ozone concentration of 0.1 to 4%, based on absolutely dry cellulose. The formamidine sulfinic acid is used in the subsequent alkaline extraction step without additional equipment.

Dabei liegt die Stoffichte der Pulpe zwischen 5 und 10 %, bevorzugt 8 und 12 %,The pulp is between 5 and 10%, preferably 8 and 12%,

Die normale Verweilzeit in dieser Stufe reicht im allgemeinen aus, um die Stabilisierung der Viskosität zu erreichen.The normal residence time in this stage is generally sufficient to stabilize the viscosity.

Weitere Bleichschritte können sich dann anschließen.Further bleaching steps can then follow.

Mit Hilfe des erfindungsgemäßen Verfahrens gelingt es, in einer chlorfreien Bleiche Zellstoffe zu erhalten, die sich in Weißgehalt, Viskosität und Festigkeit praktisch nicht von den mit den konventionellen, d. h. unter Verwendung von Chlor arbeitenden Verfahren erhaltenen unterscheiden.With the help of the method according to the invention it is possible to obtain pulp in a chlorine-free bleach which practically does not differ in terms of whiteness, viscosity and strength from those with the conventional, i.e. H. distinguish obtained using chlorine working methods.

Selbst bei hohen Ozon-Dosierungen (∼ 3 %) sind die Unterschiede äußerst gering.The differences are extremely small, even with high ozone doses (∼ 3%).

BeispieleExamples

(Die Prozentangaben sind auf atro Zellstoff bezogen)(The percentages are based on dry cellulose)

1. Fichtensulfit-Papierzellstoff (Kappa 18,0)1. Spruce sulfite paper pulp (Kappa 18.0)

a) konventionelle Bleiche nach C-E-D-H Chemikalieneinsatz: Stoffdichte Zeit Temp. C 4 % Cl₂ 3 % 1 h 25 °C E 2 % NaOH 10 % 1,5 h 70 °C D 1 % ClO₂ (Aktivchlor) 10 % 3 h 70 °C H 1 % NaOCl 10 % 3 h 40 °C Resultat:
Weiße 90.7 (ISO)
Viskosität 12.2 mPa s

Figure imgb0001
Resultat:
Weiße 90.3 (ISO)
Viskosität 8./2 mPa s
Figure imgb0002
 Resultät: Weiße 90.5 (ISO), Viskosität: 12.3 mPa s a) conventional bleaching after CEDH chemical use: Consistency time Temp. C. 4% Cl₂ 3% 1 h 25 ° C E 2% NaOH 10% 1.5 h 70 ° C D 1% ClO₂ (active chlorine) 10% 3 h 70 ° C H 1% NaOCl 10% 3 h 40 ° C Result:
White 90.7 (ISO)
Viscosity 12.2 mPa s
Figure imgb0001
 Result:
White 90.3 (ISO)
Viscosity 8./2 mPa s
Figure imgb0002
 Result: whiteness 90.5 (ISO), viscosity: 12.3 mPa s

2. Nadelholz-Kraftzellstoff (Kappa 33.2)2.Softwood kraft pulp (Kappa 33.2)

a) konventionell: CD-E-D-E-D Stoffdichte Zeit Temp. CD 7 % Cl₂ /0,7 % ClO₂ 3 % 1 h 25 °C E 2,8 % NaOH 10 % 1,5 h 60 °C D 3 % O₃ 10 % 3 h 65 °C E 1 % NaOH 10 % 1 h 65 °C D 1 % ClO₂ 10 % 3 h 70 °C Resultat:
Weiße 90.7 (ISO)
Viskosität 20.2 mPa s
Festigkeit bei 20 SR: Reißlänge 8.8 km
Durchreißwiderstand 9.3 mN m²/g b) chlorfreie Bleiche nach O-Z-E-P Stoffdichte Zeit Temp. 0.5 MPaO₂ O 5 % NaOH, 0,3 % MgSO₄ 10 % 1,5 h 110 °C Z 3 % O₃ 33 % 25 min 30 °C E 1 % NaOH 10 % 1,5 h 60 °C P 2 % H₂O₂, 0,8 % NaOH 0,2 % MgSO₄, 1 % Wasserglas 20 % 2 h 75 °C Resultat:
Weiße 89.8 (ISO)
Viskosität 12.1 mPa s
Festigkeit bei 20 SR: Reißlänge 6.8 km
Durchreißwiderstand 7.6 mN m²/g
 a) conventional: CD-EDED Consistency time Temp. CD 7% Cl₂ / 0.7% ClO₂ 3% 1 h 25 ° C E 2.8% NaOH 10% 1.5 h 60 ° C D 3% O₃ 10% 3 h 65 ° C E 1% NaOH 10% 1 h 65 ° C D 1% ClO₂ 10% 3 h 70 ° C Result:
White 90.7 (ISO)
Viscosity 20.2 mPa s
Strength at 20 SR: tear length 8.8 km
Tear resistance 9.3 mN m² / g b) chlorine-free bleaching according to OZEP Consistency time Temp. 0.5 MPaO₂ O 5% NaOH, 0.3% MgSO₄ 10% 1.5 h 110 ° C Z 3% O₃ 33% 25 min 30 ° C E 1% NaOH 10% 1.5 h 60 ° C P 2% H₂O₂, 0.8% NaOH 0.2% MgSO₄, 1% water glass 20% 2 h 75 ° C Result:
White 89.8 (ISO)
Viscosity 12.1 mPa s
Strength at 20 SR: rip length 6.8 km
Tear resistance 7.6 mN m² / g

c) chlorfreie Bleiche mit FAS in der E-Stufec) chlorine-free bleach with FAS in the E stage

E-Stufe mit 0,4 % Formamidinsulfinsäure
Resultat:
Weiße 90.1 (ISO)
Viskosität 18.7 mPa s
Festigkeit bei 20 SR: Reißlänge 8.8 km
Durchreißwiderstand 9.2 mN m²/gE stage with 0.4% formamidine sulfinic acid
Result:
White 90.1 (ISO)
Viscosity 18.7 mPa s
Strength at 20 SR: tear length 8.8 km
Tear resistance 9.2 mN m² / g

3. Buchensulfit-Zellstoff (Kappa 14.2)3. Beech sulfite pulp (Kappa 14.2)

a) konventionelle Bleiche nach C-E-H-D Stoffdichte Zeit Temp. C 4,1 % Cl₂ 3 % 1 h 20 °C E 1,8 % NaOH 10 % 1,5 h 65 °C H 1,5 % Na 10 % 2 h 40 °C D 0,7 % ClO₂ 10 % 3 h 65 °C Resultat:
Weiße 89.1 (ISO)
Festigkeit bei 25 SR: Reißlänge 5.4 km
Weiterreißarbeit 132 mNm/m
Viskosität: 12,1 mPa s; Kappa: 0,8 b) chlorfreie Bleiche nach Z-E-P Stoffdichte Zeit Temp. Z 1,5 % O₃ 35 % 20 min 20 °C E 1,8 % NaOH 10 % 1,5 h 60 °C P 1,5 % H₂O₂, 1,1 % NaOH 10 % 2 h 65 °C Resultat:
Weiße 88.2 (ISO)
Festigkeit bei 25 SR: Reißlänge 4,7 km Weiterreißarbeit 98 mNm/m
Viskosität: 7,8 mPa s; Kappa: 1,1 c) mit FAS in der Extraktionsstufe Z wie bei b) zusätzlich 0,5 % Formamidinsulfinsäure E wie bei b) P wie bei b) Resultat: Weiße 88.7 (ISO)
Festigkeit bei 25 SR: Reißlänge 5.3 km
Weiterreißbarkeit 130 mNm/m
Viskosität: 11,2 mPa s
Kappa-Wert: 1,1 a) conventional bleaching according to CEHD Consistency time Temp. C. 4.1% Cl₂ 3% 1 h 20 ° C E 1.8% NaOH 10% 1.5 h 65 ° C H 1.5% Na 10% 2 h 40 ° C D 0.7% ClO₂ 10% 3 h 65 ° C Result:
White 89.1 (ISO)
Strength at 25 SR: tearing length 5.4 km
Tear work 132 mNm / m
Viscosity: 12.1 mPa s; Kappa: 0.8 b) chlorine-free bleach according to ZEP Consistency time Temp. Z 1.5% O₃ 35% 20 min 20 ° C E 1.8% NaOH 10% 1.5 h 60 ° C P 1.5% H₂O₂, 1.1% NaOH 10% 2 h 65 ° C Result:
White 88.2 (ISO)
Strength at 25 SR: rip length 4.7 km tear tear 98 mNm / m
Viscosity: 7.8 mPa s; Kappa: 1.1 c) with FAS in the extraction stage Z as in b) an additional 0.5% formamidine sulfinic acid E as in b) P as in b) Result: White 88.7 (ISO)
Strength at 25 SR: tearing length 5.3 km
Tear resistance 130 mNm / m
Viscosity: 11.2 mPa s
Kappa value: 1.1

Claims (1)

Verfahren zur Stabilisierung der Viskosität von Zellstoffen im Anschluß an eine Ozon- bzw. Ozon-/­Sauerstoffbehandlung,
dadurch gekennzeichnet, daß man den Zellstoff bei einem pH-Wert von 8 bis 12 mit 0,05 bis 1 Gew.-% Formamidinsulfinsäure, bezogen auf atro Zellstoff, bei 40 bis 90 °C behandelt.Process for stabilizing the viscosity of cellulose following ozone or ozone / oxygen treatment,
characterized in that the pulp is treated at a pH of 8 to 12 with 0.05 to 1% by weight of formamidine sulfinic acid, based on dry cellulose, at 40 to 90 ° C.
EP90112190A 1989-07-18 1990-06-27 Process for stabilizing the viscosity of pulp Ceased EP0417411A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3923728 1989-07-18
DE3923728A DE3923728A1 (en) 1989-07-18 1989-07-18 METHOD FOR STABILIZING THE VISCOSITY OF CELLS

Publications (1)

Publication Number Publication Date
EP0417411A1 true EP0417411A1 (en) 1991-03-20

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ID=6385283

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EP90112190A Ceased EP0417411A1 (en) 1989-07-18 1990-06-27 Process for stabilizing the viscosity of pulp

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US (1) US5073301A (en)
EP (1) EP0417411A1 (en)
BR (1) BR9003292A (en)
CA (1) CA2021392A1 (en)
DE (1) DE3923728A1 (en)
FI (1) FI903433A0 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102022103081A1 (en) 2022-02-09 2023-08-10 Jan Reijnvaan pallets
DE102022103082A1 (en) 2022-02-09 2023-08-10 Jan Reijnvaan Pallet blocks and pallets

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Publication number Priority date Publication date Assignee Title
ES2111298T3 (en) * 1993-04-06 1998-03-01 Air Liquide BLEACHING OF RECYCLED PASTE WITH OZONE AND HYDROGEN PEROXIDE.
US5733412A (en) * 1995-09-13 1998-03-31 International Paper Company Decolorizing brown fibers in recycled pulp
US6428653B1 (en) 2000-12-04 2002-08-06 West Fraser Timber Co. Ltd. Method of bleaching with formamidine sulfinic acid using a reducing agent to eliminate residual peroxide
WO2012084842A1 (en) * 2010-12-22 2012-06-28 Akzo Nobel Chemicals International B.V. Process for improving chlorine dioxide bleaching of pulp

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102022103081A1 (en) 2022-02-09 2023-08-10 Jan Reijnvaan pallets
DE102022103082A1 (en) 2022-02-09 2023-08-10 Jan Reijnvaan Pallet blocks and pallets

Also Published As

Publication number Publication date
CA2021392A1 (en) 1991-01-19
BR9003292A (en) 1991-08-27
US5073301A (en) 1991-12-17
FI903433A0 (en) 1990-07-06
DE3923728A1 (en) 1991-01-24

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