WO1995013421A1 - Method of high yield paper pulp bleaching using hydrogen peroxide - Google Patents

Method of high yield paper pulp bleaching using hydrogen peroxide Download PDF

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Publication number
WO1995013421A1
WO1995013421A1 PCT/FR1994/001286 FR9401286W WO9513421A1 WO 1995013421 A1 WO1995013421 A1 WO 1995013421A1 FR 9401286 W FR9401286 W FR 9401286W WO 9513421 A1 WO9513421 A1 WO 9513421A1
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Prior art keywords
pulp
reaction medium
alcohol
hydrogen peroxide
weight
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Application number
PCT/FR1994/001286
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French (fr)
Inventor
Michel Devic
Original Assignee
Elf Atochem S.A.
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Filing date
Publication date
Application filed by Elf Atochem S.A. filed Critical Elf Atochem S.A.
Priority to DE69405006T priority Critical patent/DE69405006T2/en
Priority to EP95900797A priority patent/EP0728239B1/en
Priority to AU81473/94A priority patent/AU8147394A/en
Priority to JP7513627A priority patent/JPH09504841A/en
Publication of WO1995013421A1 publication Critical patent/WO1995013421A1/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
    • 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
    • D21C9/101—Bleaching ; Apparatus therefor in solvent medium
    • 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

  • High-yield pulp bleaching process using hydrogen peroxide The present invention relates to the bleaching of high-yield paper pulps with hydrogen peroxide.
  • wood chips are subjected to separate or associated actions of mechanical, chemical or thermal origin.
  • chemical pulps are obtained by chemical defibration of wood. Their yield is generally less than 50%.
  • yield is meant the weight of the pulp in the dry state relative to the weight of the starting lignocellulosic material in the dry state, for example wood chips in the dry state.
  • Mechanical type pulps are produced by mechanical defibration of wood chips, for example in a grinding wheel shredder or a disc shredder or refiner.
  • the yield is generally equal to or greater than 85%.
  • the mechanical characteristics of these pastes in particular the resistance to rupture, to tearing and to bursting, are poor.
  • thermomechanical pasta TMP
  • TMP thermomechanical pasta
  • the wood chips were also treated with a sodium sulfite solution at acidic or basic pH depending on the nature of the wood.
  • the pulps obtained also called chemical-mechanical pulps (CMP), have good mechanical characteristics.
  • This latter treatment consists in cooking the lignocellulosic material, carried out at a temperature equal to or greater than 100 ° C., under saturated steam pressure, in the presence of sodium sulfite or sodium bisulfite.
  • CTMP pastes are mechanical resistance is improved, the yield remaining equal to or greater than 85% and more often than not, at least equal to approximately 90% and therefore similar to that of purely mechanical origins.
  • a high-yield paper pulp is defined as being a pulp obtained by defibering the wood and various treatments with a yield equal to or greater than 85%.
  • the consistency (weight of dry matter relative to the total weight of the pulp) of the bleaching medium must be relatively high from 15 to 20% and even 30% to obtain effective bleaching.
  • the bleaching temperature should generally be between 60 ° C and 80 ° C. This temperature results in a high energy expenditure, therefore increases the cost of bleaching. At the end of bleaching, there is the problem of discharges of aqueous effluents.
  • the present invention makes it possible to avoid the drawbacks set out below or at least some of them.
  • said ratio is from 0.01 to 0.1.
  • the use of such a reaction medium makes it possible to carry out bleaching without sodium silicate.
  • bleaching can be carried out without complexing metals such as DTPA.
  • the residual bleaching liquid recoverable by filtration of the pulp can be purified by distillation and the residue from this distillation can be easily incinerated.
  • This treatment of the residual liquid avoids the rejection of aqueous bleaching effluent.
  • the ratio by weight of the alcohol to the weight of the pulp considered in the dry state is from 1 to approximately 50.
  • the consistency can vary between very large limits ranging from 50% to approximately 2%.
  • the bleaching remains very effective. This allows an easy implementation, and transport by pumping.
  • the alcohol is chosen from ethanol and ethanol. These two alcohols are available industrially in large quantities and easily evaporated or distilled for their recovery.
  • an activator of hydrogen peroxide capable of being oxidized in the medium into a peroxidant is added to the reaction medium, during its formation or during the reaction.
  • This activator can be a nitrile of general formula R-CN in which R is an alkyl or aryl group. It is assumed that this nitrile leads to an iminoperacid of general formula:
  • the alkyl group is preferably a lower alkyl chosen from methyl, ethyl and propyl.
  • the aryl group is preferably phenyl.
  • the activator can also be a mineral or organic acid or one of its salts, capable of being oxidized in the medium to a peracid or one of its salts.
  • the acid is preferably chosen from acetic acid, boric acid and boric anhydride (B2O 3 ).
  • the reaction medium also contains an alkaline agent. In fact, bleaching is more effective in the presence of such an agent.
  • this agent is chosen from sodium hydroxide, sodium carbonate, potassium carbonate.
  • the reaction medium is maintained at a temperature of 20 ° C to 80 ° C.
  • the most preferred temperature range is 50 to 60 ° C.
  • the reaction medium formed is filtered to obtain a solid and a filtrate, then the solid thus collected is washed with water to give a wet paste. whitened.
  • the high-yield paper pulp is washed beforehand with alcohol to reduce or even eliminate a large part of its water content before using this pulp thus washed to form the bleaching reaction medium.
  • the hydrogen peroxide used is a solution of pure H 2 ⁇ 2 in water at a content ranging from 10 to 70% by weight. Unless otherwise indicated, all the quantities of reagents are expressed in% by weight of pure reagent relative to the pulp considered in the dry state.
  • the sodium hydroxide solution in water can contain from 40 g to 700 g of pure NaOH per liter.
  • the activator is generally used in an amount of 1 to 50%.
  • the soda can be added all at once with the other reagents or else added little by little during the bleaching so as to keep the pH constant.
  • the apparent pH is measured with a CHEMTRIX pH meter fitted with an INGOLD glass electrode ref. 9823.
  • the reaction medium is then heated with stirring for 4 hours at a temperature of 50 ° C.
  • the dough is filtered and washed with water.
  • the filtrates are combined and the residual hydrogen peroxide is assayed to determine the amount by weight relative to the amount by weight of initial pulp considered in the dry state: 1.4%.
  • the washed dough is neutralized with sulfur dioxide at a pH equal to 5.5 and the whiteness of the dough is measured according to ISO standard, ie 75 ° ISO.

Abstract

Bleaching process characterized in that a heterogeneous reactive medium is formed containing the pulp, an alcohol and hydrogen peroxide in an aqueous solution, the weight ratio of all the water of the medium to the alcohol being 0.001 to 0.5.

Description

Procédé de blanchiment par le peroxyde d'hydrogène d'une pâte à papier à haut rendement. La présente invention concerne le blanchiment des pâtes à papier à haut rendement par le peroxyde d'hydrogène. High-yield pulp bleaching process using hydrogen peroxide. The present invention relates to the bleaching of high-yield paper pulps with hydrogen peroxide.
Pour obtenir une pâte, on soumet des copeaux de bois à des actions séparées ou associées d'origine mécaniqυ- chimique ou thermique.To obtain a paste, wood chips are subjected to separate or associated actions of mechanical, chemical or thermal origin.
-ues pâtes chimiques sont obtenues par défibrage chimique du bois. Leur rendement est, en général, inférieur à 50 %.chemical pulps are obtained by chemical defibration of wood. Their yield is generally less than 50%.
Par rendement, on entend le poids de la pâte à l'état sec rapporté au poids de la matière lignocellulosique de départ à l'état sec par exemple des copeaux de bois à l'état sec.By yield is meant the weight of the pulp in the dry state relative to the weight of the starting lignocellulosic material in the dry state, for example wood chips in the dry state.
Les pâtes de type mécanique sont fabriquées par défibrage mécanique des copeaux de bois, par exemple dans un défibreur à meule ou bien un défibreur ou raffineur à disques. Le rendement est généralement égal ou supérieur à 85 %. Cependant, les caractéristiques mécaniques de ces pâtes, notamment la résistance à la rupture, à la déchirure et à l'éclatement, sont médiocres.Mechanical type pulps are produced by mechanical defibration of wood chips, for example in a grinding wheel shredder or a disc shredder or refiner. The yield is generally equal to or greater than 85%. However, the mechanical characteristics of these pastes, in particular the resistance to rupture, to tearing and to bursting, are poor.
Pour améliorer ces caractéristiques mécaniques, on a fait subir aux copeaux de bois, avant défibrage, un traitement thermique par de la vapeur d'eau à une température de 100° à 140°C. Les pâtes ainsi obtenues sont appelées pâtes thermomécaniques (TMP) . Elles présentent cependant une blancheur médiocre.To improve these mechanical characteristics, the wood chips were subjected, before defibration, to a heat treatment with water vapor at a temperature of 100 ° to 140 ° C. The pasta thus obtained is called thermomechanical pasta (TMP). However, they exhibit poor whiteness.
On a aussi traité les copeaux de bois par une solution de sulfite de sodium à pH acide ou basique selon la nature du bois. Les pâtes obtenues, appelées aussi pâtes chimicomécaniques (CMP) , présentent de bonnes caractéristiques mécaniques.The wood chips were also treated with a sodium sulfite solution at acidic or basic pH depending on the nature of the wood. The pulps obtained, also called chemical-mechanical pulps (CMP), have good mechanical characteristics.
On a pu aussi considérablement augmenter la résistance des pâtes mécaniques, en faisant subir, aux copeaux de bois, un traitement à l'aide d'un ou plusieurs agents chimiques combiné à des opérations de chauffage et de défibrage mécanique. Ces pâtes sont appelées pâtes chimicothermomécaniques (CTMP) .It was also possible to considerably increase the resistance of mechanical pulps, by subjecting the wood chips to a treatment using one or more chemical agents combined with heating and mechanical defibration. These pastes are called chemothermal-mechanical pastes (CTMP).
Ce dernier traitement consiste en une cuisson de la matière lignocellulosique, réalisée à une température égale ou supérieure à 100°C, sous pression de vapeur d'eau saturée, en présence de sulfite de sodium ou de bisulfite de sodium.This latter treatment consists in cooking the lignocellulosic material, carried out at a temperature equal to or greater than 100 ° C., under saturated steam pressure, in the presence of sodium sulfite or sodium bisulfite.
L'intérêt de ces pâtes CTMP est que leur résistance mécanique est améliorée, le rendement restant égal ou supérieur à 85 % et le plus souvent, au moins égal à environ 90 % et donc semblable à celui des pâtes d'origine purement mécanique.The advantage of these CTMP pastes is that their mechanical resistance is improved, the yield remaining equal to or greater than 85% and more often than not, at least equal to approximately 90% and therefore similar to that of purely mechanical origins.
Pour la suite une pâte à papier à haut rendement est défini comme étant une pâte ayant été obtenue par défibrage du bois et traitements divers avec un rendement égal ou supérieur à 85 %.Hereinafter, a high-yield paper pulp is defined as being a pulp obtained by defibering the wood and various treatments with a yield equal to or greater than 85%.
Ces pâtes hauts rendements ont souvent une blancheur considérée comme insuffisante pour être utilisables pour la fabrication de papier à haut niveau de blancheur.These high yield pulps often have a whiteness considered insufficient to be usable for the production of paper with a high whiteness level.
Il est connu de procéder au blanchiment de ces pâtes par le peroxyde d'hydrogène en milieu aqueux alcalin en présence de complexants des métaux comme leIt is known practice to bleach these pastes with hydrogen peroxide in an alkaline aqueous medium in the presence of complexing agents of metals such as
DTPA (Diéthylène tétramine pentacétate de sodium) et de stabilisant de H2O2 comme le silicate de sodium. Ce type de procédé de blanchiment comporte des inconvénients.DTPA (Diethylene tetramine pentacetate of sodium) and stabilizer of H2O 2 like sodium silicate. This type of bleaching process has drawbacks.
Le silicate de sodium entraîne souvent des dépôts dans les appareillages. La consistance (poids de matière sèche par rapport au poids total de la pâte) du milieu de blanchiment doit être relativement élevée de 15 à 20 % et même de 30 % pour obtenir un blanchiment efficace.Sodium silicate often leads to deposits in the equipment. The consistency (weight of dry matter relative to the total weight of the pulp) of the bleaching medium must be relatively high from 15 to 20% and even 30% to obtain effective bleaching.
Cette consistance élevée conduit à un milieu épais qui n'est pas transportable par pompage. De plus, la température de blanchiment doit être comprise généralement entre 60°C et 80°C. Cette température entraîne une forte dépense énergétique, donc augmente le coût du blanchiment. A la fin du blanchiment, se pose le problème des rejets d'effluents aqueux. La présente invention permet d'éviter les inconvénients énoncés ci-dessous ou au moins certains d'entre eux.This high consistency leads to a thick medium which is not transportable by pumping. In addition, the bleaching temperature should generally be between 60 ° C and 80 ° C. This temperature results in a high energy expenditure, therefore increases the cost of bleaching. At the end of bleaching, there is the problem of discharges of aqueous effluents. The present invention makes it possible to avoid the drawbacks set out below or at least some of them.
Elle consiste plus précisément en un procédé de blanchiment d'une pâte à papier à haut rendement par le peroxyde d'hydrogène, caractérisé en ce qu'on forme un milieu reactionnel hétérogène contenant la pâte, un alcool et du peroxyde d'hydrogène en solution aqueuse, le rapport en poids de l'eau totale du milieu sur l'alcool étant de 0,001 à 0,5.It consists more precisely in a process for bleaching a high-yield paper pulp with hydrogen peroxide, characterized in that a heterogeneous reaction medium is formed containing the pulp, an alcohol and hydrogen peroxide in solution aqueous, the ratio by weight of the total water of the medium to the alcohol being from 0.001 to 0.5.
De préférence ledit rapport est de 0,01 à 0,1. La mise en oeuvre d'un tel milieu reactionnel permet d'effectuer le blanchiment sans silicate de sodium.Preferably said ratio is from 0.01 to 0.1. The use of such a reaction medium makes it possible to carry out bleaching without sodium silicate.
De même le blanchiment peu être réalisé sans complexant de métaux tel le DTPA.Similarly, bleaching can be carried out without complexing metals such as DTPA.
Lorsque le milieu contient très peu d'eau, le liquide résiduel de blanchiment récupérable par filtration de la pâte, peut être purifié par distillation et le résidu de cette distillation peut être incinéré facilement. Ce traitement du liquide résiduel évite le rejet d'effluent aqueux de blanchiment. Avantageusement, le rapport en poids de l'alcool sur le poids de la pâte considérée à l'état sec est de 1 à environ 50. Ainsi la consistance peut varier entre des limites très grandes allant de 50 % à environs 2 %. A ces faibles consistances de 2 à 3 %, le blanchiment reste très efficace. Cela permet une mise en oeuvre facile, et le transport par pompage.When the medium contains very little water, the residual bleaching liquid recoverable by filtration of the pulp can be purified by distillation and the residue from this distillation can be easily incinerated. This treatment of the residual liquid avoids the rejection of aqueous bleaching effluent. Advantageously, the ratio by weight of the alcohol to the weight of the pulp considered in the dry state is from 1 to approximately 50. Thus the consistency can vary between very large limits ranging from 50% to approximately 2%. At these low consistencies of 2 to 3%, the bleaching remains very effective. This allows an easy implementation, and transport by pumping.
De préférence l'alcool est choisi parmi le éthanol et l'éthanol. Ces deux alcools sont disponibles industriellement en grande quantité et facilement évaporables ou distillables pour leur récupération. Avantageusement, on ajoute au milieu reactionnel, lors de sa formation ou en cours de réaction, un activateur du peroxyde d'hydrogène apte à être oxydé dans le milieu en un peroxydant. Cet activateur peut être un nitrile de formule générale R-CN dans laquelle R est un groupe alkyle ou aryle. Il est supposé que ce nitrile conduit à un iminoperacide de formule générale:Preferably the alcohol is chosen from ethanol and ethanol. These two alcohols are available industrially in large quantities and easily evaporated or distilled for their recovery. Advantageously, an activator of hydrogen peroxide capable of being oxidized in the medium into a peroxidant is added to the reaction medium, during its formation or during the reaction. This activator can be a nitrile of general formula R-CN in which R is an alkyl or aryl group. It is assumed that this nitrile leads to an iminoperacid of general formula:
VV
R-Cχ OOHRC χ OOH
Le groupe alkyle est de préférence, un alkyle inférieur choisi parmi méthyle, éthyle et propyle.The alkyl group is preferably a lower alkyl chosen from methyl, ethyl and propyl.
Le groupe aryle est de préférence un phényle. L"activateur peut être également un acide minéral ou organique ou un de ses sels, apte à être oxydé dans le milieu en un peracide ou un de ses sels.The aryl group is preferably phenyl. The activator can also be a mineral or organic acid or one of its salts, capable of being oxidized in the medium to a peracid or one of its salts.
L'acide est de préférence choisi parmi l'acide acétique, l'acide borique et l'anhydride borique (B2O3) . De préférence, le milieu reactionnel contient de plus un agent alcalin. En effet, le blanchiment est plus efficace en présence d'un tel agent.The acid is preferably chosen from acetic acid, boric acid and boric anhydride (B2O 3 ). Preferably, the reaction medium also contains an alkaline agent. In fact, bleaching is more effective in the presence of such an agent.
Avantageusement, cet agent est choisi parmi l'hydroxyde de sodium, le carbonate de sodium, le carbonate de potassium.Advantageously, this agent is chosen from sodium hydroxide, sodium carbonate, potassium carbonate.
De préférence, on maintient le milieu reactionnel à une température de 20°C à 80°C.Preferably, the reaction medium is maintained at a temperature of 20 ° C to 80 ° C.
La gamme de température la plus préférée est de 50 à 60°C. A la fin de la réaction de blanchiment qui habituellement peut être comprise entre 15 minutes et 6 heures, on filtre le milieu reactionnel formé pour obtenir un solide et un filtrat, puis le solide ainsi recueilli est lavé à l'eau pour donner une pâte humide blanchie. De préférence, la pâte à papier à haut rendement est au préalable lavée avec l'alcool pour diminuer voir éliminer une grande partie de sa teneur en eau avant d'utiliser cette pâte ainsi lavée pour former le milieu reactionnel de blanchiment. Partie expérimentaleThe most preferred temperature range is 50 to 60 ° C. At the end of the bleaching reaction which usually can be between 15 minutes and 6 hours, the reaction medium formed is filtered to obtain a solid and a filtrate, then the solid thus collected is washed with water to give a wet paste. whitened. Preferably, the high-yield paper pulp is washed beforehand with alcohol to reduce or even eliminate a large part of its water content before using this pulp thus washed to form the bleaching reaction medium. Experimental part
D'une manière générale le peroxyde d'hydrogène mis en oeuvre est une solution de H2θ2 pur dans l'eau à une teneur allant de 10 à 70 % en poids. Sauf si autrement indiqué, toutes les quantités de réactifs sont exprimés en % en poids de réactif pur par rapport à la pâte à papier considéré à l'état sec.In general, the hydrogen peroxide used is a solution of pure H 2 θ2 in water at a content ranging from 10 to 70% by weight. Unless otherwise indicated, all the quantities of reagents are expressed in% by weight of pure reagent relative to the pulp considered in the dry state.
La solution de soude dans 1 'eau peut contenir de 40 g à 700 g de NaOH pur par litre. L'activateur est généralement mis en oeuvre en une quantité de 1 à 50 %.The sodium hydroxide solution in water can contain from 40 g to 700 g of pure NaOH per liter. The activator is generally used in an amount of 1 to 50%.
La soude peut être ajoutée en une 1 seule fois avec les autres réactifs ou bien ajoutée peu à peu pendant le blanchiment de manière à maintenir le pH constant.The soda can be added all at once with the other reagents or else added little by little during the bleaching so as to keep the pH constant.
Le pH apparent est mesuré avec un pH-mètre CHEMTRIX muni d'une électrode en verre INGOLD réf. 9823.The apparent pH is measured with a CHEMTRIX pH meter fitted with an INGOLD glass electrode ref. 9823.
La présente invention sera encore mieux comprise à l'aide des exemples suivants. Exemple 1The present invention will be understood more clearly with the aid of the following examples. Example 1
21,5 g de pâte TMP de résineux d'une blancheur initiale de 60° ISO, contenant 4 g de matière sèche, sont lavés successivement deux fois avec 50 ml de méthanol. Cette pâte, dont la teneur en eau a fortement diminuée, est mise en suspension dans 150 g de méthanol. On ajoute en tant qu'activateur 0,6 g de benzonitrile, 0,6 ml d'une solution molaire d'H2NaP04, puis 0,176 ml d'une solution d'H202 à 70 %, soit l'équivalent de 0,16 g de H202 à 100%. On ajoute 5 ml d'une solution NaOH molaire21.5 g of TMP softwood pulp with an initial whiteness of 60 ° ISO, containing 4 g of dry matter, are washed successively twice with 50 ml of methanol. This paste, whose water content has greatly decreased, is suspended in 150 g of methanol. 0.6 g of benzonitrile, 0.6 ml of a molar solution of H2NaP0 4 are added as activator, then 0.176 ml of a 70% H 2 02 solution, the equivalent of 0 , 16 g of 100% H 2 0 2 . 5 ml of a molar NaOH solution are added
(soit 0,2 g de NaOH à 100 %) . Le pH apparent du milieu est de 10. Le milieu reactionnel est alors chauffé sous agitation pendant 4 heures à une température de 50°C.(i.e. 0.2 g of 100% NaOH). The apparent pH of the medium is 10. The reaction medium is then heated with stirring for 4 hours at a temperature of 50 ° C.
On filtre la pâte et on la lave avec de l'eau. Les filtrats sont réunis et on dose le peroxyde d'hydrogène résiduel pour en déterminer la quantité en poids rapportée à la quantité en poids de pâte initiale considérée à l'état sec: 1,4 %.The dough is filtered and washed with water. The filtrates are combined and the residual hydrogen peroxide is assayed to determine the amount by weight relative to the amount by weight of initial pulp considered in the dry state: 1.4%.
La pâte lavée est neutralisée par de l'anhydride sulfureux à un pH égal à 5,5 et on mesure la blancheur de la pâte selon la norme ISO, soit 75° ISO.The washed dough is neutralized with sulfur dioxide at a pH equal to 5.5 and the whiteness of the dough is measured according to ISO standard, ie 75 ° ISO.
Le tableau suivant rapporte d'autres exemples pratiqués de manière analogue à l'exemple 1, et classés selon les quantités croissantes de H2O2 consommée. Dans chacun des ces exemples, on met en oeuvre 21,5 g de cette même pâte TMP (4 g de matière sèche) à 60° ISO. Dans ce tableau: -l'expression "H2O2 chargée" représente en % le rapport de poids de H2O2 considérée à l'état pur (100%) sur le poids de la pâte initiale considérée à 1" état sec, -1' expression "Agent alcalin chargé" représente en % le rapport du poids de l'agent alcalin (soude ou carbonate de sodium) considéré à l'état pur (100 %) sur le poids de la pâte considérée à l'état sec, -1' expression "H2O2 consommée" représente en % le rapport du poids de H2O2 consommée sur le poids de la pâte initiale considérée à l'état sec.The following table reports other examples practiced analogously to Example 1, and classified according to the increasing amounts of H 2 O 2 consumed. In each of these examples, 21.5 g of this same TMP paste (4 g of dry matter) are used at ISO 60 °. In this table: -the expression "loaded H2O2" represents in% the weight ratio of H2O 2 considered in the pure state (100%) to the weight of the initial pulp considered in 1 "dry state, -1 'expression "Charged alkaline agent" represents in% the ratio of the weight of the alkaline agent (soda or sodium carbonate) considered in the pure state (100%) to the weight of the pulp considered in the dry state, -1 ′ expression "H 2 O 2 consumed" represents in% the ratio of the weight of H 2 O2 consumed to the weight of the initial pulp considered in the dry state.
Ce tableau montre que la consommation de H2O2 augmente dans le même sens que le pH apparent mesuré. La consommation varie également en fonction de la quantité d'H2θ2 chargée.
Figure imgf000009_0001
This table shows that the consumption of H 2 O 2 increases in the same direction as the apparent pH measured. Consumption also varies depending on the amount of H2θ 2 charged.
Figure imgf000009_0001

Claims

REVENDICATIONS
1. Procédé de blanchiment d'une pâte à papier à haut rendement par le peroxyde d'hydrogène, caractérisé en ce qu'on forme un milieu reactionnel hétérogène contenant la pâte, un alcool et du peroxyde d'hydrogène en solution aqueuse, le rapport en poids de l'eau totale du milieu sur l'alcool étant de 0,001 à 0,5.1. Process for bleaching a high-yield paper pulp with hydrogen peroxide, characterized in that a heterogeneous reaction medium is formed containing the pulp, an alcohol and hydrogen peroxide in aqueous solution, the ratio by weight of the total water of the medium over the alcohol being from 0.001 to 0.5.
2. Procédé suivant la revendication 1, caractérisé en ce que ledit rapport est de 0,01 à 0,1. 2. Method according to claim 1, characterized in that said ratio is from 0.01 to 0.1.
3. Procédé suivant l'une des revendications 1 et 2, caractérisé en ce que le rapport en poids de l'alcool sur le poids de la pâte considérée à l'état sec est de 1 à 50.3. Method according to one of claims 1 and 2, characterized in that the ratio by weight of the alcohol to the weight of the pulp considered in the dry state is from 1 to 50.
4. Procédé suivant l'une des revendications 1 à 3, caractérisé en ce que l'alcool est choisi parmi le méthanol et l'éthanol.4. Method according to one of claims 1 to 3, characterized in that the alcohol is chosen from methanol and ethanol.
5. Procédé suivant l'une des revendications 1 à 4, caractérisé en ce qu'on ajoute au milieu reactionnel, lors de sa formation ou en cours de réaction, un activateur du peroxyde d'hydrogène apte à être oxydé dans le milieu en un peroxydant.5. Method according to one of claims 1 to 4, characterized in that one adds to the reaction medium, during its formation or during the reaction, an activator of hydrogen peroxide capable of being oxidized in the medium to a peroxidizer.
6. Procédé suivant la revendication 5, caractérisé en ce que l'activateur est un nitrile de formule générale R-CN dans laquelle R est un groupe alkyle ou aryle.6. Method according to claim 5, characterized in that the activator is a nitrile of general formula R-CN in which R is an alkyl or aryl group.
7. Procédé suivant la revendication 5, caractérisé en ce que l'activateur est un acide minéral ou organique.7. Method according to claim 5, characterized in that the activator is a mineral or organic acid.
8. Procédé suivant la revendication 6, caractérisé en ce que le groupe R est choisi parmi méthyle, éthyle et phényle.8. Method according to claim 6, characterized in that the group R is chosen from methyl, ethyl and phenyl.
9. Procédé suivant l'une des revendications 1 à 8, caractérisé en ce que le milieu reactionnel contient de plus un agent alcalin. 9. Method according to one of claims 1 to 8, characterized in that the reaction medium additionally contains an alkaline agent.
10. Procédé suivant la revendication 9, caractérisé en ce que l'agent alcalin est choisi parmi l'hydroxyde de sodium, le carbonate de sodium, le carbonate de potassium.10. Method according to claim 9, characterized in that the alkaline agent is chosen from sodium hydroxide, sodium carbonate, potassium carbonate.
11. Procédé suivant l'une des revendications 1 à 10, caractérisé en ce qu'on maintient le milieu reactionnel à une température de 20 à 80°C.11. Method according to one of claims 1 to 10, characterized in that the reaction medium is maintained at a temperature of 20 to 80 ° C.
12. Procédé suivant la revendication 11, caractérisé en ce que la température est de 50 à 60°C.12. Method according to claim 11, characterized in that the temperature is from 50 to 60 ° C.
13. Procédé suivant l'une des revendications 1 à 12, caractérisé en ce que le milieu reactionnel formé est filtré pour conduire à un solide et un filtrat, puis le solide ainsi recueilli est lavé à l'eau pour donner une pâte humide blanchie.13. Method according to one of claims 1 to 12, characterized in that the reaction medium formed is filtered to yield a solid and a filtrate, then the solid thus collected is washed with water to give a bleached wet paste.
14. Procédé suivant l'une des revendications 1 à 13, caractérisé en ce que la pâte à papier à haut rendement est au préalable lavée avec l'alcool pour diminuer voir éliminer une grande partie de sa teneur en eau avant d'utiliser cette pâte ainsi lavée pour former le milieu reactionnel de blanchiment. 14. Method according to one of claims 1 to 13, characterized in that the high-yield paper pulp is previously washed with alcohol to reduce or even eliminate a large part of its water content before using this pulp thus washed to form the bleaching reaction medium.
PCT/FR1994/001286 1993-11-10 1994-11-07 Method of high yield paper pulp bleaching using hydrogen peroxide WO1995013421A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE69405006T DE69405006T2 (en) 1993-11-10 1994-11-07 METHOD FOR HYDROGEN PEROXYPE BLEACHING FROM A HIGH-EXCHANGE CELL
EP95900797A EP0728239B1 (en) 1993-11-10 1994-11-07 Method of high yield paper pulp bleaching using hydrogen peroxide
AU81473/94A AU8147394A (en) 1993-11-10 1994-11-07 Method of high yield paper pulp bleaching using hydrogen peroxide
JP7513627A JPH09504841A (en) 1993-11-10 1994-11-07 Method for bleaching high-yield paper pulp using hydrogen peroxide

Applications Claiming Priority (2)

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FR93/13446 1993-11-10
FR9313446A FR2712313B1 (en) 1993-11-10 1993-11-10 Process for bleaching a high-yield paper pulp with hydrogen peroxide.

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AT (1) ATE156877T1 (en)
AU (1) AU8147394A (en)
CA (1) CA2176030A1 (en)
DE (1) DE69405006T2 (en)
FR (1) FR2712313B1 (en)
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EP0866095A1 (en) * 1997-03-13 1998-09-23 3V SIGMA S.p.A Compositions for bleaching paper

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CN1055737C (en) * 1996-01-15 2000-08-23 南京林业大学 Prescription and process for intensively bleaching pulp using singlet state oxygen in alkali bleaching stage of multi-stage process
CN1107140C (en) * 1998-05-14 2003-04-30 华南理工大学 Method for bleaching medium thick paper pulp by for hydrogen peroxide for medium-small paper mill
CN106012627B (en) * 2016-05-24 2018-05-04 中国林业科学研究院林产化学工业研究所 A kind of method that bamboo wood High brightenss bleach reducing rules are prepared using alcohols solvent
CN108642943B (en) * 2018-04-03 2021-03-19 中国林业科学研究院林产化学工业研究所 Method for preparing high-whiteness and high-strength eucalyptus chemi-mechanical pulp

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DE69405006D1 (en) 1997-09-18
CA2176030A1 (en) 1995-05-18
FR2712313A1 (en) 1995-05-19
FR2712313B1 (en) 1995-12-15
CN1139466A (en) 1997-01-01
JPH09504841A (en) 1997-05-13
ATE156877T1 (en) 1997-08-15
EP0728239A1 (en) 1996-08-28
EP0728239B1 (en) 1997-08-13
DE69405006T2 (en) 1998-01-15

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