EP0141138B1 - Process for the treatment of cellulosic materials with oxidising agents - Google Patents
Process for the treatment of cellulosic materials with oxidising agents Download PDFInfo
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- EP0141138B1 EP0141138B1 EP84110378A EP84110378A EP0141138B1 EP 0141138 B1 EP0141138 B1 EP 0141138B1 EP 84110378 A EP84110378 A EP 84110378A EP 84110378 A EP84110378 A EP 84110378A EP 0141138 B1 EP0141138 B1 EP 0141138B1
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- Prior art keywords
- process according
- oxidizing agent
- treatment
- cellulosic materials
- compounds
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Classifications
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- 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
- D21C9/1015—Bleaching ; Apparatus therefor with use of means other than pressure, temperature
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M10/00—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements
- D06M10/003—Treatment with radio-waves or microwaves
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M10/00—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements
- D06M10/04—Physical treatment combined with treatment with chemical compounds or elements
- D06M10/06—Inorganic compounds or elements
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/02—Natural fibres, other than mineral fibres
- D06M2101/04—Vegetal fibres
- D06M2101/06—Vegetal fibres cellulosic
Definitions
- the present invention relates to a process for the treatment of cellulosic materials and more particularly to paper pulps, wood chips and cellulosic textile fibers with oxidizing agents.
- Cellulosic materials intended for the manufacture of paper pulp are subjected to a large number of treatments, some of which are carried out in the presence of oxidizing agents, in particular with a view to improving their whiteness or reducing their lignin content.
- the methods known to date do not however make it possible to obtain very high whiteness gains or very extensive delignification in a single treatment. We therefore frequently use sequential treatments which generally include a very large number of stages. In addition, the duration of each particular stage is often very long.
- the cellulose fibers intended for textile applications are also subjected to certain treatments which can be carried out in the presence of oxidizing agents such as bleaching, scouring to remove the impurities, mercerizing to improve the appearance and the solidity thereof. and reduce the tendency to shrink or spray to impregnate them with reagents before maturation. All of these techniques require fairly long treatment times.
- the present invention aims to provide a process for the treatment of cellulosic materials with oxidizing agents which makes it possible to increase the efficiency of the oxidizing agent and in particular to improve the whiteness of the finished product.
- the method according to the invention also makes it possible to significantly reduce the duration of the treatment with the oxidizing agent.
- the method according to the invention also makes it possible to use significantly less solvent than the known methods, which simplifies the subsequent drying steps and reduces the effluent discharges and the consumption of solvent.
- the method according to the invention makes it possible to reduce, or even eliminate, any mechanical agitation in the treatments which required it. This is particularly the case when processing textile fibers and the manufactured products derived therefrom. One can thus avoid the harmful effects of mechanical agitation on fragile textiles such as jerseys, tulle, etc.
- the present invention relates to a process for the treatment of cellulosic materials with oxidizing agents according to which the cellulosic materials are subjected to the joint action of microwaves and at least one oxidizing agent.
- Microwaves are electromagnetic waves that have a wavelength from about 0.1 to about 100 cm, or a frequency from about 300,000 MHz to about 300 MHz. Good results have been obtained with microwaves with a frequency of 100,000 MHz to 500 MHz.
- oxidizing agents can be used. In general, they are chosen from peroxidized compounds, oxygen, ozone, permanganate as well as compounds capable of releasing active chlorine such as molecular chlorine, chlorine dioxide, hypochlorous acid, hypochlorites, chlorites and organic substances capable of releasing active chlorine. Peroxidized compounds and compounds capable of releasing active chlorine are well suited. Good results have been obtained with the peroxidized compounds.
- the peroxide compounds can be chosen from hydrogen peroxide, metal peroxides and more particularly alkali or alkaline earth metal peroxides such as sodium peroxide, inorganic persalts such as perborates, percarbonates and persulfates, inorganic peracids such as persulfuric acid, organic peracids and more particularly those containing from 2 to 7 carbon atoms such as peracetic and perpropionic acids as well as their salts and organic hydroperoxides and peroxides.
- Good results have been obtained with hydrogen peroxide, sodium peroxide, persulfuric acid, persulfates such as sodium persulfate, peracetic acid and peracetates such as sodium peracetate.
- One or more oxidizing agents of the same types or of different types can be used.
- oxidizing agents can vary within very wide limits. In general, they are used in doses of 0.001 to 10% of the weight of dry cellulosic materials (M.S.) and most often of 0.1 to 5% of the weight of dry cellulosic materials. In the case of peroxide compounds, generally 0.1 to 3% of peroxide compounds calculated in hydrogen peroxide equivalents relative to the weight of dry cellulosic materials are used.
- oxygen the partial pressure of oxygen is generally at least 100 kPa and more often than not at least 300 kPa. In general, the pressure does not exceed 20,000 kPa and in general not more than 10,000 kPa. In the case of compounds capable of releasing active chlorine, these are used in doses of 0.1 to 8% of the weight of dry cellulosic materials.
- cellulosic materials can be treated according to the method of the invention.
- these are cellulosic materials containing at least 30 and most often at least 50% by weight of compounds chosen from polysaccharides and their derivatives. These include cellulose and hemicelluloses as well as their derivatives obtained by various chemical treatments such as the acetate process, the viscose process, the ammoniacal copper process, etc. It is thus possible to apply the method according to the invention to the treatment of paper pulps of all types such as mechanical, thermomechanical, semi-chemical, chemical and mechanochemical pulps as well as to recovery pulps, at any stage of their manufacture, including the stages of pulping, bleaching and treatments prior to the manufacture of the sheet of paper or cardboard.
- the method is thus suitable for the treatment of wood as well as wood chips or other wood particles intended to be used for the manufacture of paper pulps such as mechanical, thermomechanical or mechanochemical pulps. It can also be applied to the treatment of cellulosic materials other than wood intended for the manufacture of paper pulps such as straw, reeds, bagasse and bamboo.
- the cellulosic materials according to the invention can also be chosen from natural cellulosic textile fibers such as linen, cotton, hemp, ramie, jute and sisal and artificial textile fibers such as rayon, viscose rayon, cuproammoniac rayon and cellulose acetate as well as manufactured textiles.
- natural cellulosic textile fibers such as linen, cotton, hemp, ramie, jute and sisal and artificial textile fibers such as rayon, viscose rayon, cuproammoniac rayon and cellulose acetate as well as manufactured textiles.
- the method according to the invention is particularly suitable for the treatment of paper pulps and more especially for the treatment of chemical pulps such as sulphate, sulphite or bisulphite pulp. It is also well suited for the treatment of wood particles and more particularly wood chips, in particular for their pretreatment before a mechanical pulping process. Good results have been obtained in the treatment of possibly semi-bleached sulphate doughs.
- the process according to the invention is generally carried out in the presence of a solvent.
- the solvent is most often water.
- the amount of solvent at the start of the treatment according to the invention can vary within wide limits. It is most often at least 0.1% and generally does not exceed 99.5% of the total weight of the mixture subjected to the action of microwaves and which essentially comprises cellulosic materials, solvent, oxidizing agents and any additives.
- the solvent is water
- the amount of water at the start of the treatment according to the invention is generally at least 0.5% and most often at least 1% of the total weight of the mixture; it generally does not exceed 95% most often not 90%, and preferably not 85% of the total weight of the mixture.
- the density at the start of the treatment according to the invention is generally at least 5% and most often at least 8%. It does not generally exceed 99% and most often not 98%.
- the density which we are talking about here, expresses the consistency or dryness of the paper pulp and is measured in%, ie g dry pulp / 100 g mixture pulp + water + reagents).
- the process according to the invention can be carried out in the presence of other additives.
- the oxidizing agent is not itself capable of imparting the proper pH to the mixture
- compounds with an alkaline character that is to say capable of imparting to the water a pH equal to or greater than 7 or compounds with an acidic character, that is to say capable of imparting a pH of less than 7 to water, or alternatively pH regulators such as buffers.
- the alkali compounds can be hydroxides or carbonates of alkali metals or ammonium, and more particularly sodium hydroxide, or sodium silicate.
- the alkali metal or ammonium bicarbonates can be chosen as pH regulators.
- Sulfuric acid can be chosen as an acidic compound.
- the process according to the invention is generally carried out in the presence of a compound of alkaline character.
- the dose of compound with an alkaline character is generally 0.1 to 20% of the weight of dry cellulosic materials.
- the pH is generally equal to or greater than 7, more particularly from 7 to 13 and most often from 8 to 12.
- oxidizing agent when the latter is likely to deactivate during the treatment. This is particularly the case when the oxidizing agent is a peroxide compound. In general, they are used in amounts of 0.01 to 5% of the weight of dry cellulosic materials.
- additives can also be used depending on the particular applications.
- sequestering agents surfactants, agents capable of protecting the cellulosic chains to prevent their depolymerization, wetting agents, activating agents, anticorrosion agents, antistatic agents, desizing agents, optical brighteners , dispersing agents, anti-scaling agents, foaming agents and collecting agents.
- surfactants agents capable of protecting the cellulosic chains to prevent their depolymerization
- wetting agents wetting agents
- activating agents anticorrosion agents
- antistatic agents desizing agents
- optical brighteners optical brighteners
- dispersing agents anti-scaling agents
- foaming agents and collecting agents are generally coated at doses of 0.01 to 10% of the weight of dry cellulosic materials.
- the cellulosic materials subjected to the treatment according to the invention can have, before this treatment, very diverse temperatures. They can thus have, before the treatment according to the invention, temperatures ranging from ambient temperature, that is to say approximately 10 to 25 ° C., up to temperatures of 200 ° C.
- the temperature of the cellulosic materials before the treatment according to the invention depends on the existence or not of a previous treatment. Most often the temperature of the cellulosic materials before the treatment according to the invention is the ambient temperature or that which they have acquired during the possible previous treatment. In most cases, the temperature of the cellularosic materials before the treatment according to the invention is from 10 to 90 ° C.
- the duration of the treatment according to the invention is variable. In general, it is 0.1 to 120 minutes and most often 0.2 to 30 minutes. It is generally shorter than that of the corresponding treatments using oxidizing agents without the intervention of microwaves.
- the process according to the invention can be carried out continuously or batchwise.
- the method according to the invention can be implemented in various industries and in particular in the paper industry and in the textile industry.
- the method according to the invention is also well suited for bleaching paper pulps of all types already formed. It can thus be applied at various stages of bleaching consecutive to pulping or cooking. It is particularly suitable for the treatment of unbleached pasta, especially the alkaline pasta collected after washing after cooking, mainly in the case of chemical pasta such as kraft pasta, or for the treatment of pasta before entering the towers. extraction. It is also well suited for bleaching semi-bleached pasta.
- the method according to the invention is well suited for the treatment of pressed or dried pasta.
- the pasta can be pressed or dried by means of various devices suitable for these uses and known by themselves. It is thus possible to use cylinder, screw or belt presses or conventional dryers or “flash-dryers”. Pasta can come in various forms such as leaves or "flocks”.
- the method according to the invention can also be applied to the various treatments with oxidizing agents to which the cellulosic textile fibers are subjected. This is the case with scalding, mercerizing, bleaching and impregnation such as spraying before maturation. These impregnations can be done in various devices known by. themselves operating either continuously such as “pad-steam”, “J-box” and “U-box” and continuous pressurized vaporizers, or semi-continuous such as "pad-roll”, or finally discontinuously such as turnstile boats, autoclaves, spinners, "Jigger” and “kier”.
- the method according to the invention is well suited for the pretreatment of the fibers before they are sent to one or other of the abovementioned treatments.
- Example 2R was carried out for comparison.
- a semi-bleached softwood kraft pulp according to the CEH sequence of initial whiteness 63.6 ° ISO (standard ISO 2470) was used.
- the dough was previously "fluffed” (reduced to fluff) in a household mixer.
- the dry paste is introduced into a polyethylene bag where it is moistened by spraying with an aqueous solution of hydrogen peroxide. It is then exposed to a microwave beam of a frequency of approximately 2450 MHz in a household microwave oven of TOSHIBA brand ER-649 ET-S with rotary table set in the "DEFROST" position for five minutes (test 1) or in an oven maintained at 100 ° C for five minutes (test 2R).
- the whiteness of the dough was measured relative to the whiteness of BaS0 4 measured by means of an ELREPHO reflectometer (ZEISS) equipped with the R457 filter and a gloss trap (ISO 2470 standard).
- ZEISS ELREPHO reflectometer equipped with the R457 filter and a gloss trap (ISO 2470 standard).
- the consumption of hydrogen peroxide was measured by assaying the residual hydrogen peroxide in the presence of paste.
- test 3 Three tests were carried out at different acid (tests 3 and 4) and basic (test 5) pH under conditions close to those of Example 1.
- the dough is then wrung, "fluffed” and dried in a ventilated oven at 40 ° C.
- the dry paste is then subjected to the same treatment as in Example 1.
- Example 1 The same semi-bleached kraft pulp as that used for the production of Examples 1 and 2R was treated with hydrogen peroxide under the same conditions as in Example 1 (test 6) and in Example 2R (test 7R) except, however, the density which has been adjusted to 15%.
- test 8 and 10 were carried out under the same conditions as test 6, tests 9R and 11 R, under the same conditions as test 7R.
- test 12 was carried out under the same conditions as test 6, test 13R under the same conditions as test 7R.
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- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
- Paper (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Cephalosporin Compounds (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
- Detergent Compositions (AREA)
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Abstract
Description
La présente invention concerne un procédé pour le traitement des matières cellulosiques et plus particulièrement des pâtes à papier, des copeaux de bois et des fibres textiles cellulosiques par des agents oxydants.The present invention relates to a process for the treatment of cellulosic materials and more particularly to paper pulps, wood chips and cellulosic textile fibers with oxidizing agents.
Les matières cellulosiques destinées à la fabrication de pâtes à papier sont soumises à un grand nombre de traitements dont certains sont réalisés en présence d'agents oxydants notamment en vue d'améliorer leur blancheur ou de réduire leur teneur en lignine. Les procédés connus à ce jour ne permettent cependant pas d'obtenir des gains de blancheur très élevés ni une délignifcation très poussée en un seul traitement. Aussi a-t-on fré- quemment recours à des traitements séquentiels qui comportent en général un très grand nombre de stades. En outre, la durée de chaque stade particulier est souvent fort longue.Cellulosic materials intended for the manufacture of paper pulp are subjected to a large number of treatments, some of which are carried out in the presence of oxidizing agents, in particular with a view to improving their whiteness or reducing their lignin content. The methods known to date do not however make it possible to obtain very high whiteness gains or very extensive delignification in a single treatment. We therefore frequently use sequential treatments which generally include a very large number of stages. In addition, the duration of each particular stage is often very long.
De même les fibres cellulosiques destinées à des applications textiles sont également soumises à certains traitements qui peuvent être réalisés en présence d'agents oxydants tels que le blanchiment, le débouillissage pour en éliminer les impuretés, le mercerisage pour en améliorer l'aspect et la solidité et réduire la tendance au rétrécissement ou le vaporisage pour les imprégner de réactifs avant maturation. Toutes ces techniques nécessitent des durées de traitement assez longues.Likewise, the cellulose fibers intended for textile applications are also subjected to certain treatments which can be carried out in the presence of oxidizing agents such as bleaching, scouring to remove the impurities, mercerizing to improve the appearance and the solidity thereof. and reduce the tendency to shrink or spray to impregnate them with reagents before maturation. All of these techniques require fairly long treatment times.
La présente invention vise à fournir un procédé pour le traitement des matières cellulosiques par des agents oxydants qui permet d'augmenter l'efficacité de l'agent oxydant et notamment d'améliorer la blancheur du produit fini. Le procédé selon l'invention permet en outre de réduire sensiblement la durée du traitement par l'agent oxydant. Le procédé selon l'invention permet également de mettre en oeuvre nettement moins de solvant que les procédés connus ce qui simplifie les étapes de séchage ultérieures et réduit les rejets d'effluents et la consommation de solvant. Enfin le procédé selon l'invention permet de réduire, voire de supprimer, toute agitation mécanique dans les traitements qui en nécessitaient. Il en est ainsi notamment lors du traitement des fibres textiles et des produits manufacturés qui en dérivent. On peut ainsi éviter les effets néfastes de l'agitation mécanique sur des textiles fragiles tels que les jerseys, les tulles, etc.The present invention aims to provide a process for the treatment of cellulosic materials with oxidizing agents which makes it possible to increase the efficiency of the oxidizing agent and in particular to improve the whiteness of the finished product. The method according to the invention also makes it possible to significantly reduce the duration of the treatment with the oxidizing agent. The method according to the invention also makes it possible to use significantly less solvent than the known methods, which simplifies the subsequent drying steps and reduces the effluent discharges and the consumption of solvent. Finally, the method according to the invention makes it possible to reduce, or even eliminate, any mechanical agitation in the treatments which required it. This is particularly the case when processing textile fibers and the manufactured products derived therefrom. One can thus avoid the harmful effects of mechanical agitation on fragile textiles such as jerseys, tulle, etc.
La présente invention concerne un procédé pour le traitement des matières cellulosiques par des agents oxydants selon lequel on soumet les matières cellulosiques à l'action conjointe de microondes et d'au moins un agent oxydant.The present invention relates to a process for the treatment of cellulosic materials with oxidizing agents according to which the cellulosic materials are subjected to the joint action of microwaves and at least one oxidizing agent.
Les microondes sont des ondes électromagnétique qui ont une longueur d'onde d'environ 0,1 à environ 100 cm, soit une fréquence d'environ 300 000 MHz à environ 300 MHz. De bons résultats ont été obtenus avec des microondes d'une fréquence de 100 000 M Hz à 500 M Hz.Microwaves are electromagnetic waves that have a wavelength from about 0.1 to about 100 cm, or a frequency from about 300,000 MHz to about 300 MHz. Good results have been obtained with microwaves with a frequency of 100,000 MHz to 500 MHz.
Divers agents oxydants peuvent être mis en oeuvre. En général, ils sont choisis parmi les composés peroxydés, l'oxygène, l'ozone, le permanganate ainsi que les composés capables de libérer du chlore actif tels que le chlore moléculaire, le dioxyde de chlore, l'acide hypochloreux, les hypochlorites, les chlorites et les substances organiques capables de libérer du chlore actif. Les composés peroxydés et les composés capables de libérer du chlore actif conviennent bien. De bons résulats ont été obtenus avec les composés peroxydés. Les composés peroxydés peuvent être choisis parmi le peroxyde d'hydrogène, les peroxydes métalliques et plus particulièrement les peroxydes de métaux alcalins ou alcalinoterreux tels que le peroxyde de sodium, les persels inorganiques tels que les perborates, les percarbona- tes et les persulfates, les peracides inorganiques tels que l'acide persulfurique, les peracides organiques et plus particulièrement ceux contenant de 2 à 7 atomes de carbone tels que les acides peracétique et perpropionique ainsi que leurs sels et les hydroperoxydes et peroxydes organiques. De bons résultats ont été obtenus avec le peroxyde d'hydrogène, le peroxyde de sodium, l'acide persulfurique, les persulfates tels que le persulfate de sodium, l'acide peracétique et les peracétates tels que le peracétate de sodium. Les meilleurs résultats ont été obtenus avec le peroxyde d'hydrogène. On peut mettre en oeuvre un ou plusieurs agents oxydants de mêmes types ou de types différents.Various oxidizing agents can be used. In general, they are chosen from peroxidized compounds, oxygen, ozone, permanganate as well as compounds capable of releasing active chlorine such as molecular chlorine, chlorine dioxide, hypochlorous acid, hypochlorites, chlorites and organic substances capable of releasing active chlorine. Peroxidized compounds and compounds capable of releasing active chlorine are well suited. Good results have been obtained with the peroxidized compounds. The peroxide compounds can be chosen from hydrogen peroxide, metal peroxides and more particularly alkali or alkaline earth metal peroxides such as sodium peroxide, inorganic persalts such as perborates, percarbonates and persulfates, inorganic peracids such as persulfuric acid, organic peracids and more particularly those containing from 2 to 7 carbon atoms such as peracetic and perpropionic acids as well as their salts and organic hydroperoxides and peroxides. Good results have been obtained with hydrogen peroxide, sodium peroxide, persulfuric acid, persulfates such as sodium persulfate, peracetic acid and peracetates such as sodium peracetate. The best results have been obtained with hydrogen peroxide. One or more oxidizing agents of the same types or of different types can be used.
Les doses d'agents oxydants peuvent varier dans de très larges limites. En général ils sont mis en oeuvre à des doses de 0,001 à 10% du poids de matières cellulosiques sèches (M.S.) et le plus souvent de 0,1 à 5% du poids de matières cellulosiques sèches. Dans le cas de composés peroxydés, on met en général en ceuvre de 0,1 à 3% de composés peroxydés calculés en équivalents peroxyde d'hydrogène par rapport au poids de matières cellulosiques sèches. Lors de la mise en oeuvre d'oxygène, la pression partielle en oxygène est en général d'au moins 100 kPa et le plus souvent d'au moins 300 kPa. En général, la pression ne dépasse pas 20 000 kPa et en général pas 10 000 kPa. Dans le cas des composés capables de libérer du chlore actif, ceux-ci sont mis en oeuvre à des doses de 0,1 à 8% du poids de matières cellulosiques sèches.The doses of oxidizing agents can vary within very wide limits. In general, they are used in doses of 0.001 to 10% of the weight of dry cellulosic materials (M.S.) and most often of 0.1 to 5% of the weight of dry cellulosic materials. In the case of peroxide compounds, generally 0.1 to 3% of peroxide compounds calculated in hydrogen peroxide equivalents relative to the weight of dry cellulosic materials are used. When using oxygen, the partial pressure of oxygen is generally at least 100 kPa and more often than not at least 300 kPa. In general, the pressure does not exceed 20,000 kPa and in general not more than 10,000 kPa. In the case of compounds capable of releasing active chlorine, these are used in doses of 0.1 to 8% of the weight of dry cellulosic materials.
Diverses matières cellulosiques peuvent être traitées selon le procédé de l'invention. En général, il s'agit de matières cellulosiques contenant au moins 30 et le plus souvent au moins 50% en poids de composés choisis parmi les polysaccharides et leurs dérivés. Ceux-ci comprennent les cellulose et les hémicelluloses ainsi que leurs dérivés obtenus par divers traitements chimiques tels que le procédé à l'acétate, le procédé à la viscose, le procédé au cuivre ammoniacal, etc. On peut ainsi appliquer le procédé selon l'invention au traitement des pâtes à papier de tous types telles que les pâtes mécaniques, thermomécaniques, semi-chimiques, chimiques et mécanochimiques ainsi qu'aux pâtes de récupération, à un stade quelconque de leur fabrication, en ce compris les stades de mise en pâte, de blanchiment et les traitements préalables à la fabrication de la feuille de papier ou de carton. On peut également l'appliquer au bois, ou à toutes les particules de bois telles que les copeaux de bois. Le procédé convient ainsi pour le traitement du bois ainsi que des copeaux de bois ou des autres particules de bois destinées à être utilisés pour la fabrication de pâtes à papier telles que des pâtes mécaniques, thermomécaniques ou mécanochimiques. On peut également l'appliquer au traitement de matières cellulosiques autres que le bois destinées à la fabrication de pâtes à papier telles que la paille, les roseaux, la bagasse et le bambou.Various cellulosic materials can be treated according to the method of the invention. In general, these are cellulosic materials containing at least 30 and most often at least 50% by weight of compounds chosen from polysaccharides and their derivatives. These include cellulose and hemicelluloses as well as their derivatives obtained by various chemical treatments such as the acetate process, the viscose process, the ammoniacal copper process, etc. It is thus possible to apply the method according to the invention to the treatment of paper pulps of all types such as mechanical, thermomechanical, semi-chemical, chemical and mechanochemical pulps as well as to recovery pulps, at any stage of their manufacture, including the stages of pulping, bleaching and treatments prior to the manufacture of the sheet of paper or cardboard. You can also use the app quer au bois, or all wood particles such as wood chips. The method is thus suitable for the treatment of wood as well as wood chips or other wood particles intended to be used for the manufacture of paper pulps such as mechanical, thermomechanical or mechanochemical pulps. It can also be applied to the treatment of cellulosic materials other than wood intended for the manufacture of paper pulps such as straw, reeds, bagasse and bamboo.
Les matières cellulosiques selon l'invention peuvent également être choisies parmi les fibres textiles naturelles cellulosiques telles que le lin, le coton, le chanvre, la ramie, le jute et le sisal et les fibres textiles artificielles telles que la rayonne, la rayonne viscose, la rayonne cuproammoniacale et l'acétate de cellulose ainsi que les textiles manufacturés.The cellulosic materials according to the invention can also be chosen from natural cellulosic textile fibers such as linen, cotton, hemp, ramie, jute and sisal and artificial textile fibers such as rayon, viscose rayon, cuproammoniac rayon and cellulose acetate as well as manufactured textiles.
Le procédé selon l'invention convient particulièrement bien pour le traitement des pâtes à papier et plus spécialement pour le traitement des pâtes chimiques telles que les pâtes au sulfate, au sulfite ou au bisulfite. Il convient également bien pour le traitement des particules de bois et plus particulièrement des copeaux de bois notamment pour leur prétraitement avant un procédé mécanique de mise en pâte. De bons résultats ont été obtenus lors du traitement des pâtes au sulfate éventuellement semi-blanchies.The method according to the invention is particularly suitable for the treatment of paper pulps and more especially for the treatment of chemical pulps such as sulphate, sulphite or bisulphite pulp. It is also well suited for the treatment of wood particles and more particularly wood chips, in particular for their pretreatment before a mechanical pulping process. Good results have been obtained in the treatment of possibly semi-bleached sulphate doughs.
Le procédé selon l'invention est réalisé en général en présence d'un solvant. Le solvant est le plus souvent l'eau. La quantité de solvant au début du traitement selon l'invention peut varier dans de larges limites. Elle est le plus souvent d'au moins 0,1% et ne dépasse en général pas 99,5% du poids total du mélange soumis à l'action des microondes et qui comprend essentiellement les matières cellulosiques, le solvant, les agents oxydants et les additifs éventuels. Lorsque le solvant est l'eau, la quantité d'eau au début du traitement selon l'invention est en général d'au moins 0,5% et le plus souvent d'au moins 1 % du poids total du mélange; elle ne dépasse en général pas 95% le plus souvent pas 90%, et de préférence pas 85% du poids total du mélange.The process according to the invention is generally carried out in the presence of a solvent. The solvent is most often water. The amount of solvent at the start of the treatment according to the invention can vary within wide limits. It is most often at least 0.1% and generally does not exceed 99.5% of the total weight of the mixture subjected to the action of microwaves and which essentially comprises cellulosic materials, solvent, oxidizing agents and any additives. When the solvent is water, the amount of water at the start of the treatment according to the invention is generally at least 0.5% and most often at least 1% of the total weight of the mixture; it generally does not exceed 95% most often not 90%, and preferably not 85% of the total weight of the mixture.
Lors du traitement de pâtes à papier de toutes origines, vierges ou de recyclage, la densité au début du traitement selon l'invention est en général d'au moins 5% et le plus souvent d'au moins 8%. Elle ne dépasse en géneral pas 99% et le plus souvent pas 98%.When treating paper pulp of all origins, virgin or recycled, the density at the start of the treatment according to the invention is generally at least 5% and most often at least 8%. It does not generally exceed 99% and most often not 98%.
(La densité, dont il est question ici, exprime la consistance ou la siccité de la pâte à papier et se mesure en %, c'est à dire g pâte seche/100 g me- lange pâte + eau + reactifs).(The density, which we are talking about here, expresses the consistency or dryness of the paper pulp and is measured in%, ie g dry pulp / 100 g mixture pulp + water + reagents).
Le procédé selon l'invention peut être réalisé en présence d'autres additifs. Ainsi lorsque l'agent oxydant n'est pas lui-même capable de conférer au mélange le pH adéquat, on peut ajouter des composés à caractère alcalin c'est-à-dire capables de conférer à l'eau un pH égal ou supérieur à 7 ou des composés à caractère acide c'est-à-dire capable de conférer à l'eau un pH inférieur à 7 ou encore des régulateurs de pH tels que des tampons. Les composés à caractère alcalins peuvent être des hydroxydes ou carbonats de métaux alcalins ou d'ammonium, et plus particulièrement de l'hydroxyde de sodium, ou du silicate de sodium. Les bicarbonates de métaux alcalins ou d'ammonium peuvent être choisi comme régulateurs de pH. L'acide sulfurique peut être choisi comme composé à caractère acide. Le procédé selon l'invention est en général réalisé en présence d'un composé à caractère alcalin. La dose de composé à caractère alcalin est en général de 0,1 à 20% du poids de matières cellulosiques sèches.The process according to the invention can be carried out in the presence of other additives. Thus, when the oxidizing agent is not itself capable of imparting the proper pH to the mixture, it is possible to add compounds with an alkaline character, that is to say capable of imparting to the water a pH equal to or greater than 7 or compounds with an acidic character, that is to say capable of imparting a pH of less than 7 to water, or alternatively pH regulators such as buffers. The alkali compounds can be hydroxides or carbonates of alkali metals or ammonium, and more particularly sodium hydroxide, or sodium silicate. The alkali metal or ammonium bicarbonates can be chosen as pH regulators. Sulfuric acid can be chosen as an acidic compound. The process according to the invention is generally carried out in the presence of a compound of alkaline character. The dose of compound with an alkaline character is generally 0.1 to 20% of the weight of dry cellulosic materials.
Dans le cas du traitement des copeaux de bois, du blanchiment des pâtes à papier ou des fibres textiles, notamment par des composés peroxydés ou par des composés capables de libérer du chlore actif et de préférence par des composés peroxydés tels que le peroxyde d'hydrogène, le pH est en général égal ou supérieur à 7 plus particulièrement de 7 à 13 et le plus souvent de 8 à 12.In the case of the treatment of wood shavings, the bleaching of paper pulp or textile fibers, in particular by peroxidized compounds or by compounds capable of releasing active chlorine and preferably by peroxidized compounds such as hydrogen peroxide , the pH is generally equal to or greater than 7, more particularly from 7 to 13 and most often from 8 to 12.
On peut également mettre en oeuvre des stabilisants de l'agent oxydant lorsque ce dernier est susceptible de se désactiver au cours du traitement. Tel est le cas notamment lorsque l'agent oxydant est un composé peroxydé. En général, ils sont mis en oeuvre en quantités de 0,01 à 5% du poids de matières cellulosiques sèches.It is also possible to use stabilizers of the oxidizing agent when the latter is likely to deactivate during the treatment. This is particularly the case when the oxidizing agent is a peroxide compound. In general, they are used in amounts of 0.01 to 5% of the weight of dry cellulosic materials.
On peut également mettre en oeuvre divers autres additifs selon les applications particulières. Parmi ceux-ci figurent des agents séquestrants, des agents tensioactifs, des agents capables de protéger les chaînes cellulosiques pour éviter leur dépolymérisation, des agents mouillants, des agents activants, des agents anticorrosion, des agents antistatiques, des agents de désensimage, des azurants optiques, des agents dispersants, des agents antiincrustants, des agents moussants et des agents collecteurs. Ces additifs sont en général mis en couvre à des doses de 0,01 à 10% du poids de matières cellulosiques sèches.Various other additives can also be used depending on the particular applications. Among these are sequestering agents, surfactants, agents capable of protecting the cellulosic chains to prevent their depolymerization, wetting agents, activating agents, anticorrosion agents, antistatic agents, desizing agents, optical brighteners , dispersing agents, anti-scaling agents, foaming agents and collecting agents. These additives are generally coated at doses of 0.01 to 10% of the weight of dry cellulosic materials.
Les matières cellulosiques soumises au traitement selon l'invention peuvent avoir, avant ce traitement, des températures très diverses. Elles peuvent ainsi avoir, avant le traitement selon l'invention, des températures allant de la température ambiante, c'est-à-dire environ 10 à 25 °C, jusqu'à des températures de 200 °C. En général, la température des matières cellulosiques avant le traitement selon l'invention dépend de l'existence ou non d'un traitement antérieur. Le plus souvent la température des matières cellulosiques avant le traitement selon l'invention est la température ambiante ou celle qu'elles ont acquises lors de l'éventuel traitement précédent. Dans la plupart des cas, la température des matières céllulosiques avant le traitement selon l'invention est de 10 à 90 °C.The cellulosic materials subjected to the treatment according to the invention can have, before this treatment, very diverse temperatures. They can thus have, before the treatment according to the invention, temperatures ranging from ambient temperature, that is to say approximately 10 to 25 ° C., up to temperatures of 200 ° C. In general, the temperature of the cellulosic materials before the treatment according to the invention depends on the existence or not of a previous treatment. Most often the temperature of the cellulosic materials before the treatment according to the invention is the ambient temperature or that which they have acquired during the possible previous treatment. In most cases, the temperature of the celulosic materials before the treatment according to the invention is from 10 to 90 ° C.
La durée du traitement selon l'invention est variable. En général, elle est de 0,1 à 120 minutes et le plus souvent de 0,2 à 30 minutes. Elle est en général plus courte que celle des traitements correspondants au moyen d'agents oxydants sans l'intervention de microondes.The duration of the treatment according to the invention is variable. In general, it is 0.1 to 120 minutes and most often 0.2 to 30 minutes. It is generally shorter than that of the corresponding treatments using oxidizing agents without the intervention of microwaves.
Le procédé selon l'invention peut être réalisé en continu ou en discontinu.The process according to the invention can be carried out continuously or batchwise.
Les conditions précises de réalisation du procédé selon l'intervention ainsi que la nature des autres additifs éventuels mis en ceuvre, peuvent varier dans de larges limites selon le type de matières cellulosiques à traiter et le but particulier du traitement concerné. En général ces traitements sont réalisés en faisant tremper les matières cellulosiques dans des solutions aqueuses d'agents oxydants ou en les imprégnant au moyen de telle solutions.The precise conditions for carrying out the process according to the intervention, as well as the nature of the other possible additives used, can vary within wide limits depending on the type of cellulosic material to be treated and the particular purpose of the treatment concerned. In general, these treatments are carried out by soaking the cellulosic materials in aqueous solutions of oxidizing agents or by impregnating them by means of such solutions.
Le procédé selon l'invention peut être mis en oeuvre dans diverses industries et notamment dans l'industrie papetière et dans l'industrie textile.The method according to the invention can be implemented in various industries and in particular in the paper industry and in the textile industry.
Ainsi, loars de la fabrication de pâtes à papier mécaniques, on peut traiter, selon le procédé de l'invention, des particules de bois telles que des copeaux au moyen d'agents oxydants tels que les composés peroxydés, avant leur mise en pâte dans des appareils tels que dès raffineurs. Cette opération peut se faire en même temps que ou après le «presteaming». Le procédé selon l'invention peut également prendre place après le passage en raffineur ou entre deux passages en raffineurs.Thus, loars of the manufacture of mechanical paper pulps, it is possible to treat, according to the method of the invention, wood particles such as shavings by means of oxidizing agents such as peroxidized compounds, before their pulping in devices such as refiners. This can be done at the same time as or after the "presteaming". The process according to the invention can also take place after passing through a refiner or between two passing through refiners.
Le procédé selon l'invention convient également bien pour le blanchiment de pâtes à papier de tous types déjà formées. Il peut ainsi être appliqué à divers stades de blanchiment consécutifs à la mise en pâte ou à la cuisson. Il convient particulièrement bien pour le traitement des pâtes écrues notamment les pâtes alcalines recueillies après les lavages consécutifs à la cuisson principalement dans le cas de pâtes chimiques telles que les pâtes kraft, our pour le traitement des pâtes avant l'entrée dans les tours d'extraction. Il convient également bien pour le blanchiment des pâtes semi-blanchies.The method according to the invention is also well suited for bleaching paper pulps of all types already formed. It can thus be applied at various stages of bleaching consecutive to pulping or cooking. It is particularly suitable for the treatment of unbleached pasta, especially the alkaline pasta collected after washing after cooking, mainly in the case of chemical pasta such as kraft pasta, or for the treatment of pasta before entering the towers. extraction. It is also well suited for bleaching semi-bleached pasta.
Le procédé selon l'invention convient bien pour le traitement de pâtes pressées ou séchées. Les pâtes peuvent être pressées ou séchées au moyen de divers appareils convenant pour ces usages et connus par eux-mêmes. On peut ainsi utiliser des presses à cylindres, à vis ou à bande ou des séchoirs classiques ou des «flash-dryers». Les pâtes peuvent se présenter sous des formes diverses telles que des feuilles ou des «flocks» (flocons).The method according to the invention is well suited for the treatment of pressed or dried pasta. The pasta can be pressed or dried by means of various devices suitable for these uses and known by themselves. It is thus possible to use cylinder, screw or belt presses or conventional dryers or “flash-dryers”. Pasta can come in various forms such as leaves or "flocks".
Le procédé selon l'invention peut s'appliquer également aux divers traitement par des agents oxydants auxquels sont soumises les fibres textiles cellulosiques. Il en est ainsi du débouillissage, du mercerisage, du blanchiment et des imprégnations telles que le vaporisage avant maturation. Ces imprégnations peuvent se faire dans divers appareils connus par. eux-mêmes fonctionnant soit en continu tels que les «pad-steam», les «J-box» et les «U-box» et les vaporisateurs continus sous pression, soit en semi-continu tels que les «pad-roll», soit enfin en discontinu tels que les barques à tourniquet, les autoclaves, les tournettes, les «Jigger» et les «kier». Le procédé selon l'invention convient bien pour le prétraitement des fibres avant qu'elles ne soient envoyées à l'un ou l'autre des traitements précités.The method according to the invention can also be applied to the various treatments with oxidizing agents to which the cellulosic textile fibers are subjected. This is the case with scalding, mercerizing, bleaching and impregnation such as spraying before maturation. These impregnations can be done in various devices known by. themselves operating either continuously such as "pad-steam", "J-box" and "U-box" and continuous pressurized vaporizers, or semi-continuous such as "pad-roll", or finally discontinuously such as turnstile boats, autoclaves, spinners, "Jigger" and "kier". The method according to the invention is well suited for the pretreatment of the fibers before they are sent to one or other of the abovementioned treatments.
Afin d'illustrer l'invention sans pour autant en limiter la portée, on donne ci-après des exemples pratiques de réalisation. L'exemple 2R a été réalisé à titre de comparaison.In order to illustrate the invention without limiting its scope, practical examples of implementation are given below. Example 2R was carried out for comparison.
Une pâte kraft de résineux semi-blanchie selon la séquence CEH de blancheur initiale 63,6° ISO (norme ISO 2470) a été utilisée. La pâte a été au préalable «fluffée» (réduite en peluches) dans un malaxeur ménager.A semi-bleached softwood kraft pulp according to the CEH sequence of initial whiteness 63.6 ° ISO (standard ISO 2470) was used. The dough was previously "fluffed" (reduced to fluff) in a household mixer.
La pâte sèche est introduite dans un sac en polyéthylène où elle est humidifiée par pulvérisation d'une solution aqueuse de peroxyde d'hydrogène. Elle est ensuite exposée à un faisceau de microondes d'une fréquence d'environ 2450 MHz dans un four à microondes ménager de marque TOSHIBA modèle ER-649 ET-S avec table tournante mis en position «DEFROST» pendant cinq minutes (essai 1 ) ou dans une étuve maintenue à 100 °C pendant cinq minutes (essai 2R).The dry paste is introduced into a polyethylene bag where it is moistened by spraying with an aqueous solution of hydrogen peroxide. It is then exposed to a microwave beam of a frequency of approximately 2450 MHz in a household microwave oven of TOSHIBA brand ER-649 ET-S with rotary table set in the "DEFROST" position for five minutes (test 1) or in an oven maintained at 100 ° C for five minutes (test 2R).
La blancheur de la pâte a été mesurée par rapport à la blancheur de BaS04 mesurée au moyen d'un réflectomètre ELREPHO (ZEISS) équipé du filtre R457 et d'un piège à brillance (norme ISO 2470).The whiteness of the dough was measured relative to the whiteness of BaS0 4 measured by means of an ELREPHO reflectometer (ZEISS) equipped with the R457 filter and a gloss trap (ISO 2470 standard).
La consommation de peroxyde d'hydrogène a été mesurée par dosage du peroxyde d'hydrogène résiduaire en présence de pâte.The consumption of hydrogen peroxide was measured by assaying the residual hydrogen peroxide in the presence of paste.
Les conditions opératoires et les résultats obtenus sont donnés au tableau I ci-après.
Trois essais ont été réalisés à differents pH acides (essais 3 et 4) et basique (essai 5) dans des conditions voisines de celles de l'exemple 1.Three tests were carried out at different acid (tests 3 and 4) and basic (test 5) pH under conditions close to those of Example 1.
La même pâte semi-blanchie que celle utilisée pour la réalisation des exemples 1 et 2R a été soumise à un défibrage préalable en présence d'acide sulfurique (essais 3 et 4) ou d'hydroxyde de sodium (essai 5) de manière à ajuster le pH respectivement aus valeurs 5, 7 et 9.The same semi-bleached pulp as that used for the production of Examples 1 and 2R was subjected to prior defibration in the presence of sulfuric acid (tests 3 and 4) or sodium hydroxide (test 5) so as to adjust pH 5, 7 and 9 respectively.
La pâte est ensuite essorée, «fluffée» et séchée en étuve ventilée à 40 °C. La pâte seche est ensuite soumise au même traitement qu'à l'exemple 1.The dough is then wrung, "fluffed" and dried in a ventilated oven at 40 ° C. The dry paste is then subjected to the same treatment as in Example 1.
Les conditions opératoires et les résultats obtenus sont donnés au tableau ici-après.
La même pâte kraft semi-blanchie que celle utilisée pour la réalisation des exemples 1 et 2R a été traitée par le peroxyde d'hydrogène dans les mêmes conditions qu'à l'exemple 1 (essai 6) et à l'exemple 2R (essai 7R) excepté toutefois la densité qui a été réglée à 15%.The same semi-bleached kraft pulp as that used for the production of Examples 1 and 2R was treated with hydrogen peroxide under the same conditions as in Example 1 (test 6) and in Example 2R (test 7R) except, however, the density which has been adjusted to 15%.
Les conditions opératoires et les résultats obtenus sont donnés au tableau I ci-après.
On a traité la même pâte semi-blanchie qu'aux exemples 1 et 2R avec de l'hypochloride de sodium. Les essais 8 et 10 ont été réalisés dans les mêmes conditions que l'essai 6, les essais 9R et 11 R, dans les mêmes conditions que l'essai 7R.The same semi-bleached paste as in Examples 1 and 2R was treated with sodium hypochloride. Tests 8 and 10 were carried out under the same conditions as test 6, tests 9R and 11 R, under the same conditions as test 7R.
Les conditions opératoires et les résultats obtenus sont donnés au tableau IV ci-après.
On a traité la même pâte semi-blanchie qu'aux exemples 1 et 2R avec du dioxyde de chlore. On a réalisé l'essai 12 dans les mêmes conditions que l'essai 6, l'essai 13R dans les mêmes conditions que l'essai 7R.The same semi-bleached paste as in Examples 1 and 2R was treated with chlorine dioxide. Test 12 was carried out under the same conditions as test 6, test 13R under the same conditions as test 7R.
Les conditions opératoires et les résultats obtenus sont donnés au tableau V ci-après.
Claims (10)
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---|---|---|---|---|
FR1011405A (en) * | 1949-02-01 | 1952-06-23 | Improvements to processes for the treatment of cellulose-based materials by ultrasound, in particular those for the manufacture of paper pulps | |
CH341707A (en) * | 1955-02-08 | 1959-10-15 | Zellstoffverfahrens Ag | Process for increasing the swelling value of fibers in suspension |
FR1342601A (en) * | 1962-12-28 | 1963-11-08 | Application of ultrasound to the finishing of artificial or synthetic textile products | |
US3632299A (en) * | 1969-09-19 | 1972-01-04 | Us Agriculture | Shrinkproofing of animal fibers by passing said through an electrical discharge zone containing ozone |
US3695825A (en) * | 1970-03-30 | 1972-10-03 | Magyar Viscosa Gyar | Acoustic method for the posttreatment of fibers |
JPS58219005A (en) * | 1982-06-15 | 1983-12-20 | 松下電工株式会社 | Method of impregnating treating liquid |
-
1983
- 1983-09-16 FR FR8314900A patent/FR2552125B1/en not_active Expired
-
1984
- 1984-08-30 PT PT79157A patent/PT79157B/en not_active IP Right Cessation
- 1984-08-31 EP EP84110378A patent/EP0141138B1/en not_active Expired
- 1984-08-31 AT AT84110378T patent/ATE31753T1/en not_active IP Right Cessation
- 1984-08-31 DE DE8484110378T patent/DE3468454D1/en not_active Expired
- 1984-09-05 FI FI843468A patent/FI71963C/en not_active IP Right Cessation
- 1984-09-05 AU AU32737/84A patent/AU560277B2/en not_active Ceased
- 1984-09-05 IN IN697/DEL/84A patent/IN161416B/en unknown
- 1984-09-06 CA CA000462543A patent/CA1228452A/en not_active Expired
- 1984-09-06 NZ NZ209471A patent/NZ209471A/en unknown
- 1984-09-13 US US06/650,066 patent/US4576609A/en not_active Expired - Fee Related
- 1984-09-14 BR BR8404609A patent/BR8404609A/en not_active IP Right Cessation
- 1984-09-14 NO NO843644A patent/NO164789C/en unknown
- 1984-09-14 ES ES535928A patent/ES535928A0/en active Granted
- 1984-09-14 JP JP59193814A patent/JPS6088191A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4128256C1 (en) * | 1991-08-27 | 1993-04-15 | H. Krantz Gmbh & Co, 5100 Aachen, De | |
US9347661B2 (en) | 2006-10-26 | 2016-05-24 | Xyleco, Inc. | Processing biomass |
Also Published As
Publication number | Publication date |
---|---|
EP0141138A1 (en) | 1985-05-15 |
PT79157B (en) | 1986-11-18 |
IN161416B (en) | 1987-11-28 |
NO164789B (en) | 1990-08-06 |
CA1228452A (en) | 1987-10-27 |
FI843468A (en) | 1985-03-17 |
AU560277B2 (en) | 1987-04-02 |
US4576609A (en) | 1986-03-18 |
ATE31753T1 (en) | 1988-01-15 |
FR2552125A1 (en) | 1985-03-22 |
FI71963B (en) | 1986-11-28 |
AU3273784A (en) | 1985-03-21 |
NZ209471A (en) | 1987-02-20 |
NO164789C (en) | 1990-11-14 |
JPS6088191A (en) | 1985-05-17 |
FI843468A0 (en) | 1984-09-05 |
FR2552125B1 (en) | 1986-03-21 |
NO843644L (en) | 1985-03-18 |
BR8404609A (en) | 1985-08-06 |
ES8603602A1 (en) | 1985-12-16 |
PT79157A (en) | 1984-09-01 |
FI71963C (en) | 1987-03-09 |
ES535928A0 (en) | 1985-12-16 |
DE3468454D1 (en) | 1988-02-11 |
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