EP0014753B1 - Process for improving the colour and for the deodorisation of sulphate pulp - Google Patents

Process for improving the colour and for the deodorisation of sulphate pulp Download PDF

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Publication number
EP0014753B1
EP0014753B1 EP79104899A EP79104899A EP0014753B1 EP 0014753 B1 EP0014753 B1 EP 0014753B1 EP 79104899 A EP79104899 A EP 79104899A EP 79104899 A EP79104899 A EP 79104899A EP 0014753 B1 EP0014753 B1 EP 0014753B1
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EP
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Prior art keywords
pulp
peroxide
kraft
sulphate
sulfate
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Expired
Application number
EP79104899A
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German (de)
French (fr)
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EP0014753A1 (en
Inventor
Horst Dr. Krüger
Wilhelm Dr. Berndt
Jakob Wink
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Evonik Operations GmbH
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Degussa GmbH
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Application filed by Degussa GmbH filed Critical Degussa GmbH
Priority to AT79104899T priority Critical patent/ATE2019T1/en
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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

Definitions

  • Pulp which was produced by the Kraft or sulfate process, are characterized by excellent technological properties. After bleaching, they are used in large quantities for paper production.
  • the kraft or sulfate pulp In the unbleached state, the kraft or sulfate pulp is used in a not inconsiderable amount for the production of packaging materials, e.g. Cardboard boxes used. Because of its very high strength properties, the kraft or sulfate pulp is particularly suitable for packaging in which heavy mechanical stress must be expected.
  • the unbleached kraft or sulfate pulp has significant disadvantages that undesirably severely limit its use for the production of packaging material.
  • cellulose for food packaging should have a white content of 30 to 32 - without losing its good strength properties.
  • the invention relates to a process for lightening and deodorising fuel or sulfate pulp, which is characterized in that after the sulfate boil during stock preparation in the area of a diffusion wash using the residual alkalinity of the pulp suspension still present in the pulp after the alkaline boil a peroxide in an amount of 0.05 to 3 wt .-% (based on 100% peroxide), based on dry cellulose, is added.
  • an amount of peroxide of 0.5 to 2.5% by weight (100% peroxide) based on dry cellulose may be necessary, while for deodorization alone an amount of 0.05 to 0.3 wt .-% peroxide, based on dry cellulose, may be sufficient.
  • Hydrogen peroxide in aqueous solution is preferably used as the peroxide.
  • the residual alkalinity of the pulp suspension at the beginning of the addition of the peroxide can correspond to a degree of leaching of 0.2 to 1.8% by weight of Na 2 SO 4 , preferably of 1.2 to 1.5% by weight of Na 2 SO 4 .
  • the process according to the invention can be carried out at material densities in the range from 3 to 20% by weight and at temperatures in the range from 40 to 90 ° C.
  • a temperature of 60 to 70 ° C is particularly advantageous.
  • the storage time of the pulp can moreover be between 1 to 25 hours and in an advantageous embodiment 7 to 15 hours.
  • a degree of leaching that is optimal for peroxide treatment is normally achieved in the production of sulfate pulp in the area of diffusion washing. However, if this is not the case, it is necessary to correct the residual alkalinity (degree of washout).
  • the peroxide consumption will be too rapid and the result will be poor.
  • Inorganic or organic acids which do not contain reducing components can be used as the acid.
  • Sulfuric acid can advantageously be used.
  • peroxide bleaching is possible in the described phase of the kraft or sulfate pulp production process if one does not add the sodium hydroxide solution that is otherwise absolutely necessary for peroxide bleaching.
  • the use of known bleach stabilizers can also be dispensed with.
  • the kraft or sulfate pulp treated by means of the method according to the invention can be used without difficulty as a material for food packaging, e.g. Milk packs.
  • the sulfate pulp produced in a continuous cooker is passed through a final washing filter, after having passed through the usual sorting and washing operations, on which it is obtained with a degree of washing out of 1.2 to 1.5% Na 2 SO 4 .
  • the fabric is thickened to 15% fabric density on the filter, it falls into a screw at 70 ° C and is pumped into a thick material tower in which it is stored for 7 to 20 hours (diffusion tower).
  • the fabric has a white content of 26.5. 1,500 l / h of a 10% aqueous hydrogen peroxide solution are evenly distributed in the screw using a drip tray.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Artificial Filaments (AREA)
  • Saccharide Compounds (AREA)
  • Medicines Containing Material From Animals Or Micro-Organisms (AREA)

Abstract

1. A process for lightening and deodorizing kraft or sulphate pulp, characterized in that from 0.05 to 3 % by weight, based on completely dry pulp, of a peroxide (based on 100 % peroxide) are added after sulphate cooking during pulp preparation in the region of the diffusion wash using residual alkalinity of the pulp suspension which is still present in the pulp as a result of the alkaline cooking.

Description

Zellstoffe, welche nach dem Kraft- oder Sulfatverfahren erzeugt wurden, zeichnen sich durch hervorragende technologische Eigenschaften aus. Sie werden unter anderem nach einer Bleiche in grossen Mengen zur Papiererzeugung verwendet.Pulp, which was produced by the Kraft or sulfate process, are characterized by excellent technological properties. After bleaching, they are used in large quantities for paper production.

In ungebleichtem Zustand wird der Kraft-oder Sulfatzellstoff in nicht unerheblicher Menge zur Herstellung von Verpackungsmaterialien, wie z.B. Kartons, eingesetzt. Auf Grund seiner sehr hohen Festigkeitseigenschaften eignet sich der Kraft- oder Sulfatzellstoff nämlich für Verpackungen, bei denen mit starker mechanischer Beanspruchung gerechnet werden muss.In the unbleached state, the kraft or sulfate pulp is used in a not inconsiderable amount for the production of packaging materials, e.g. Cardboard boxes used. Because of its very high strength properties, the kraft or sulfate pulp is particularly suitable for packaging in which heavy mechanical stress must be expected.

Der ungebleichte Kraft- oder Sulfatzellstofs weist jedoch wesentliche Nachteile auf, die seine Verwendung zur Herstellung von Verpackungsmaterial unerwünscht stark einschränken.However, the unbleached kraft or sulfate pulp has significant disadvantages that undesirably severely limit its use for the production of packaging material.

So sind z.B. die erhaltenen Verpackungs.. materialien auf Grund der braunen Farbe des Zellstoffes unansehnlich und hässlich. Weiterhin entstehen bei der SulfatKochung intensiv riechende schwefelhaltige Verbindungen, wie, z.B. Äthyl- und Methylmerkaptan, die dem Kraft.. oder Sulfatzellstoff einen charakteristischer Geruch verleihen und bei des Waschung und Trocknung nicht mit ausreichender Sicherheit entfernt werden können. Besonders nachteilig wirken sich diese Eigenschaften des Kraft- oder Sulfatzellstoffes bei Lebensmittelverpackunger aus, so dass bisher eine Verwendung des ungebleichten Kraft- oder Sulfatzellstoffes für diesen Zweck. z.b. für Milchverpackungen, nicht möglich ist.For example, the received packaging .. materials unsightly and ugly due to the brown color of the pulp. Furthermore, sulphate-boiling compounds with a strong smell, such as e.g. Ethyl and methyl mercaptan, which give the Kraft .. or sulfate pulp a characteristic smell and cannot be removed with sufficient certainty during washing and drying. These properties of the fuel or sulfate pulp have a particularly disadvantageous effect in food packaging, so that the unbleached fuel or sulfate pulp has hitherto been used for this purpose. e.g. for milk packaging, is not possible.

Es besteht somit ein enormes Bedürfnis, auf eine wirtschaftliche vertretbare Weise mit der in Zellstoff- fabriken zur Verfügung stehenden. üblichen Anlagen den Kraft- und Sulfatzellstof aufzuhellen und zu desodorieren und somit als Material für die Herstellung von Lebensmittelverpackungen verwendbar zu machen.There is therefore an enormous need, in an economically justifiable manner, with that available in pulp mills. conventional systems to lighten and deodorize the fuel and sulfate pulp and thus make it usable as a material for the production of food packaging.

Während der ungebleichte Kraft- oder Sulfatzellstoff mit einem Weissgehalt von ca. 25 bis 26 erhaiten wird, soli Zellstoff für Lebensmittelverpackungen einen Weissgehalt von 30 bis 32 - ohne Verlust seiner guten Festigkeitseigenschaften - aufweisen.While the unbleached kraft or sulfate pulp will have a white content of approx. 25 to 26, cellulose for food packaging should have a white content of 30 to 32 - without losing its good strength properties.

Um dem Verpackungsmaterial eine ansprechende Farbe zu verleihen, genügt es, den Weissgehait des Kraft- oder Sulfatzellstoffes um ca. 5 bis 10 Punkte zu verbessern.In order to give the packaging material an appealing color, it is sufficient to improve the whiteness of the kraft or sulfate pulp by approx. 5 to 10 points.

Gegenstand der Erfindung ist ein Verfahren zum Aufhellen und Desodorieren von Kraft- oder Sulfatzellstoff, welches dadurch gekennzeichnet ist, dass man nach der Sulfat-Kochung während der Stoffaufbereitung im Bereich einer Diffusionswäsche unter Benutzung der in dem Zellstoff nach der alkalischen Kochung noch vorhandenen Restalkalität der Zellstoffsuspension ein Peroxid in einer Menge von 0,05 bis 3 Gew.-% (bezogen auf 100%iges Peroxid), bezogen auf atro-Zellstoff, zusetzt.The invention relates to a process for lightening and deodorising fuel or sulfate pulp, which is characterized in that after the sulfate boil during stock preparation in the area of a diffusion wash using the residual alkalinity of the pulp suspension still present in the pulp after the alkaline boil a peroxide in an amount of 0.05 to 3 wt .-% (based on 100% peroxide), based on dry cellulose, is added.

Dabei kann für die gewünschte Verbesserung des Weissgrades eine Menge an Peroxid von 0,5 bis 2,5 Gew.-% (100%iges Peroxid) bezogen auf atro Zellstoff notwendig sein, während für die Desodorierung allein eine Menge von 0,05 bis, 0,3 Gew.-% Peroxid, bezogen auf atro Zellstoff, ausreichend sein kann.For the desired improvement in the degree of whiteness, an amount of peroxide of 0.5 to 2.5% by weight (100% peroxide) based on dry cellulose may be necessary, while for deodorization alone an amount of 0.05 to 0.3 wt .-% peroxide, based on dry cellulose, may be sufficient.

Als Peroxid wird vorzugsweise Wasserstoffperoxid in wässriger Lösung verwendet. Die Restalkalität der Zellstoffsuspension kann zu Beginn der Zugabe des Peroxides einem Auswaschungsgrad von 0,2 bis 1,8 Gew.-% Na2S04, vorzugsweise von 1,2 bis 1,5 Gew.-% Na2S04 entsprechen. Bei dem erfindungsgemässe Verfahren ist vor allem vorteilhaft, dass in der benutzten Phase des Kraft- oder Sulfatzellstoffherstellverfahrens die Zellsoffsuspension mit einer Stoffdichte von 10 bis 15. Gew.-%, bezogen auf atro Zellstoff, bei hohen Temperaturen, welche in dem Bereich von 60 bis 80°C liegen, anfällt und mehrere Stunden, vorzugsweise 7 bis 20 Stunden, gelagert wird.Hydrogen peroxide in aqueous solution is preferably used as the peroxide. The residual alkalinity of the pulp suspension at the beginning of the addition of the peroxide can correspond to a degree of leaching of 0.2 to 1.8% by weight of Na 2 SO 4 , preferably of 1.2 to 1.5% by weight of Na 2 SO 4 . In the process according to the invention, it is particularly advantageous that in the phase of the kraft or sulfate pulp production process used, the cellulose suspension with a consistency of 10 to 15% by weight, based on dry cellulose, at high temperatures, which are in the range from 60 to 80 ° C, accumulates and is stored for several hours, preferably 7 to 20 hours.

Darüberhinaus kann das erfindungsgemässe Verfahren bei Stoffdichten im Bereich von 3 bis 20 Gew.-%, sowie bei Temperaturen im Bereich von 40 bis 90°C durchgeführt werden. Eine Temperatur von 60 bis 70°C ist besonders vorteilhaft.In addition, the process according to the invention can be carried out at material densities in the range from 3 to 20% by weight and at temperatures in the range from 40 to 90 ° C. A temperature of 60 to 70 ° C is particularly advantageous.

Die Lagerzeit des Zellstoffes kann darüberhinaus zwischen 1 bis 25 Stunden und in einer vorteilhaften Ausführungsform 7 bis 15 Stunden betragen.The storage time of the pulp can moreover be between 1 to 25 hours and in an advantageous embodiment 7 to 15 hours.

Normalerweise wird bei der Produktion von Sulfat-Zellstoff im Bereich der Diffusionswäsche ein Auswaschungsgrad erreicht, der für die Peroxidbehandlung optimal ist. Sollte dies jedoch nicht der Fall sein, so ist es notwendig, die Restalkalität (Auswaschungsgrad) zu korrigieren.A degree of leaching that is optimal for peroxide treatment is normally achieved in the production of sulfate pulp in the area of diffusion washing. However, if this is not the case, it is necessary to correct the residual alkalinity (degree of washout).

Eine zu hohe Alkalität des Zellstoffes bewirkt einen zu raschen Peroxidverbrauch und damit ein schlechtes Ergebnis. In solchen Fällen ist es vorteilhaft, das einzusetzende Peroxid mit einer adäquaten Säuremenge zu versehen, die ausreicht, die Alkalität des Zellstoffes in den optimalen Bereich zu bringen. Als Säure kann man anorganische oder organische Säuren verwenden, die keine reduzierenden Anteile beinhalten. Vorteilhafterweise kann Schwefelsäure eingesetzt werden.If the pulp is too alkaline, the peroxide consumption will be too rapid and the result will be poor. In such cases it is advantageous to provide the peroxide to be used with an adequate amount of acid which is sufficient to bring the alkalinity of the pulp into the optimum range. Inorganic or organic acids which do not contain reducing components can be used as the acid. Sulfuric acid can advantageously be used.

Das erfindungsgemässe Verfahren ist überraschenderweise in der beschriebenen Phase des Kraft- oder Sulfat-Zellstoffherstellverfahrens möglich, obwohl bekannte Rezepturen für eine Zellstoffbleiche mit Peroxid in dieser Phase des Zellstoffherstellverfahrens keine ausreichenden Ergebnisse erzielen. Es besteht daher die allgemein herrschende Meinung, dass noch aus der Kochung vorhandene, nicht ausgewaschene oxidierbare Anteile zu einem vorzeitigen Peroxidverbrauch führten und eine Bleiche unmöglich machten.He f indungsgemässe method surprisingly is described phase of the kraft or sulfate Zellstoffherstellverfahrens possible, though known recipes for pulp bleaching with peroxide do not achieve sufficient results in this phase of the Zellstoffherstellverfahrens. There is therefore the generally prevailing opinion that oxidizable fractions which are still present in the boil and have not been washed out are present led to premature peroxide consumption and made bleaching impossible.

Überraschenderweise hat sich nun bei dem erfindungsgemässen Verfahren gezeigt, das eine Peroxidbleiche in der beschriebenen Phase des Kraft- oder Sulfat-Zellstoffherstellverfahrens möglich ist, wenn man auf die Zugabe der für eine Peroxidbleiche ansonsten unbedingt notwendigen Natronlauge verzichtet. Auch auf die Mitverwendung von bekannten Bleichstabilisatoren kann verzichten werden. Der mittels am erfindungsgemässen Verfahren behandelte Kraft- oder Sulfat-Zellstoff kann ohne Schwierigkeiten als Material für Lebensmittelverpackungen, z.B. Milchpackungen, verwendet werden.Surprisingly, it has now been shown in the process according to the invention that peroxide bleaching is possible in the described phase of the kraft or sulfate pulp production process if one does not add the sodium hydroxide solution that is otherwise absolutely necessary for peroxide bleaching. The use of known bleach stabilizers can also be dispensed with. The kraft or sulfate pulp treated by means of the method according to the invention can be used without difficulty as a material for food packaging, e.g. Milk packs.

Das erfindungsgemässe Verfahren wird anhand der folenden Beispiele näher erläutert und beschrieben:The process according to the invention is explained and described in more detail with reference to the following examples:

Beispiel 1example 1

Der in einem kontinuierlichen Kocher erzeugte Sulfat-Zellstoff wird nach Durchlaufen der üblichen Sortierungs- und Waschungsoperationen über ein letztes Waschfilter geleitet, auf dem er mit einem Auswaschungsgrad von 1,2 bis 1,5% Na2S04 anfällt. Der Stoff wird am Filter auf 15% Stoffdichte eingedickt, er fällt mit 70°C in eine Schnecke und wird in einem Dickstoffturm gepumpt, in dem er 7 bis 20 Stunden lagert (Diffusionsturm).The sulfate pulp produced in a continuous cooker is passed through a final washing filter, after having passed through the usual sorting and washing operations, on which it is obtained with a degree of washing out of 1.2 to 1.5% Na 2 SO 4 . The fabric is thickened to 15% fabric density on the filter, it falls into a screw at 70 ° C and is pumped into a thick material tower in which it is stored for 7 to 20 hours (diffusion tower).

Am Turmeingang hat der Stoff 26,5 Weissgehalt. In der Schnecke werden mittels einer Tropfrinne 1.500 l/h einer 10%igen wässrigen Wasserstoffperoxidiösung gleichmässig verteilt.At the tower entrance, the fabric has a white content of 26.5. 1,500 l / h of a 10% aqueous hydrogen peroxide solution are evenly distributed in the screw using a drip tray.

Entsprechend der Produktion von 10.000 kg/h Sulfat-Zellstoff entspricht dies der Anwendung von 1,5% H202. Der nach 7 Stunden Reaktionszeit aus dem Turm kontinuierlich abgepumpte Stoff hat einen Weissgehalt von 32 bei gleichzeitiger Veränderung des Farbtons von Graubraun zu bräunlichgelb. Er ist praktisch geruchlos. Die Festigkeitseigenschaften vor und nach der Behandlung sind gleich.Corresponding to the production of 10,000 kg / h sulfate pulp, this corresponds to the use of 1.5% H 2 0 2 . After a reaction time of 7 hours, the material continuously pumped out of the tower has a white content of 32 with a simultaneous change in color from gray-brown to brownish-yellow. It is practically odorless. The strength properties before and after the treatment are the same.

Beispiel 2Example 2

!n der in Beispiel 1 beschriebenen Anlage werden an der gleichen Zugabestelle 150 1/hr einer 10%igen Wasserstoffperoxidlösung zudosiert, was auf Stoff bezogen 0,15% entspricht. Der Weissgehalt des nach 10 Stunden Reaktions- und Lagerzeit aus dem Stapelturm entnommenen Stoffes war mit 27,5 praktisch unverändert. Der zuvor eindringliche Geruch war verschwunden, so dass der Stoff für eine Produktion von Milchbecherkarton eingesetzt werden konnte.In the system described in Example 1, 150 l / hr of a 10% strength hydrogen peroxide solution are metered in at the same addition point, which corresponds to 0.15% based on the substance. The white content of the material removed from the stacking tower after a reaction and storage time of 10 hours was practically unchanged at 27.5. The previously penetrating smell had disappeared, so that the material could be used for the production of milk carton.

Claims (1)

1. A process for lightening and deodorizing kraft or sulphate pulp, characterised in that from 0.05 to 3% by weight, based on completely dry pulp, of a peroxide (based on 100% peroxide) are added after sulphate cooking during pulp preparation in the region of the diffusion wash using residual alkalinity of the pulp suspension which is still present in the pulp as a result of the alkaline cooking.
EP79104899A 1979-02-16 1979-12-04 Process for improving the colour and for the deodorisation of sulphate pulp Expired EP0014753B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79104899T ATE2019T1 (en) 1979-02-16 1979-12-04 PROCESS FOR COLOR IMPROVEMENT AND DEODORIZATION OF SULFATE PULP.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2905936A DE2905936B1 (en) 1979-02-16 1979-02-16 Process for lightening and deodorising sulfate pulp
DE2905936 1979-02-16

Publications (2)

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EP0014753A1 EP0014753A1 (en) 1980-09-03
EP0014753B1 true EP0014753B1 (en) 1982-12-15

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EP79104899A Expired EP0014753B1 (en) 1979-02-16 1979-12-04 Process for improving the colour and for the deodorisation of sulphate pulp

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EP (1) EP0014753B1 (en)
AT (1) ATE2019T1 (en)
CA (1) CA1129157A (en)
DE (2) DE2905936B1 (en)
FI (1) FI68684C (en)
NO (1) NO793959L (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2504375C1 (en) * 2012-05-23 2014-01-20 Галина Викторовна Сукоян Pharmaceutical formulation for treating diseases associated with endothelial dysfunction

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0073872A1 (en) * 1981-09-03 1983-03-16 Billerud Uddeholm AB Chemical process in the manufacture of paper
SE442414B (en) * 1981-09-22 1985-12-23 Holmens Bruk Ab SETTING TO REDUCE OR INHIBIT THE MARKING OF PASS OR PAPER IN BACKWATER SYSTEM
US4559103A (en) * 1982-08-05 1985-12-17 Honshu Seishi Kabushiki Kaisha Packaging paper and packaging material for packaging metallic material and method of producing the same

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Publication number Priority date Publication date Assignee Title
US1454339A (en) * 1921-11-28 1923-05-08 Brown Co Method of treating cellulose pulp to remove odors therefrom
US1632802A (en) * 1926-08-10 1927-06-21 Brown Co Process of and apparatus for treating fiber
US1774403A (en) * 1926-09-16 1930-08-26 Brown Co Process of producing fiber of high alpha cellulose content
US2030384A (en) * 1934-10-18 1936-02-11 Nekoosa Edwards Paper Co Method of bleaching pulp
BE450336A (en) * 1942-12-09 1943-05-31
FR2192981B1 (en) * 1972-07-21 1988-11-10 Air Liquide Fr
IT1071347B (en) * 1976-03-12 1985-04-02 Interox Sa PROCESS FOR DISINFECTION OF OLD PAPER

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Tappi, vol. 43, Nr. 10, October 1960, Seiten 806-813 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2504375C1 (en) * 2012-05-23 2014-01-20 Галина Викторовна Сукоян Pharmaceutical formulation for treating diseases associated with endothelial dysfunction

Also Published As

Publication number Publication date
DE2905936B1 (en) 1980-04-30
CA1129157A (en) 1982-08-10
NO793959L (en) 1980-08-19
FI68684C (en) 1985-10-10
EP0014753A1 (en) 1980-09-03
DE2964319D1 (en) 1983-01-20
FI793720A (en) 1980-08-17
FI68684B (en) 1985-06-28
ATE2019T1 (en) 1982-12-15

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