WO2002052101A1 - Pate chimique entierement blanchie a base de sulfite, procede de fabrication et produits derives - Google Patents

Pate chimique entierement blanchie a base de sulfite, procede de fabrication et produits derives Download PDF

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Publication number
WO2002052101A1
WO2002052101A1 PCT/EP2001/014103 EP0114103W WO02052101A1 WO 2002052101 A1 WO2002052101 A1 WO 2002052101A1 EP 0114103 W EP0114103 W EP 0114103W WO 02052101 A1 WO02052101 A1 WO 02052101A1
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Prior art keywords
bleaching
pulp
chlorine
process according
paper
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PCT/EP2001/014103
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English (en)
Inventor
Andreas Geisenheiner
Othar Kordsachia
Rudolf Patt
Armin Reinhard
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Sca Hygiene Products Gmbh
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Publication of WO2002052101A1 publication Critical patent/WO2002052101A1/fr

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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
    • D21C9/1026—Other features in bleaching processes
    • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
    • D21C3/06—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides sulfur dioxide; sulfurous acid; bisulfites sulfites

Definitions

  • the present invention relates to a completely bleached sulfite chemical pulp, a process for the production thereof and products made of this pulp (nonwovens or paper, especially tissue paper) .
  • chemical pulp is a fibrous material obtained from plant raw materials from which most non- cellulose components have been removed by chemical pulping without substantial mechanical post-treatment .
  • chemical pulping processes such as the sulfite or sulfate
  • Mechanical pulp is the general term for fibrous materials made of wood entirely or almost entirely by mechanical means, optionally at increased temperatures. Mechanical pulp is subdivided into the purely mechanical pulps
  • CMP chemo- mechanical pulp
  • CMP CMP
  • Chemical and mechanical pulp are also known by the general designation pulp.
  • the strength of papers made from chemical pulps (hereinafter abbreviated as "strength of the chemical pulp") is substantially determined by the pulping degree of the wood used as starting material .
  • the binding ability of the fibers first increases as more and more lignin is removed and reaches a maximum at a lignin content of about 10%. At this residual lignin content, the fibrous material has good stiffness and resistance to tearing along with a high binding ability.
  • the overall strength of the chemical pulp decreases due to the strong attack of most of the pulping chemicals on the carbohydrate portion (cellulose and hemicellulose) of the wood.
  • semi-chemical pulp a pulp according to DIN 6730 obtained from plant raw materials by chemical pulping from which only part of the non-fibrous components have been removed and which is subjected to mechanical post treatment;
  • CMP chemi-mechanical pulps
  • Second pulp 11 chemical pulp recovered by the sulfate process
  • lignin must be removed completely, since even small amounts of residual lignin are discolored due to chemical changes in the lignin structure (primary condensation) . This is largely carried out in a pulping process. Any residual lignin still present is then removed in several bleaching steps .
  • the native lignin is less discolored by the acidic sulfite process. For this reason, it was possible to use high- yield chemical pulps made by acidic or semi-acidic sulfite processes in unbleached form for special applications. If a higher degree of brightness was required, such chemical pulps were also bleached in a delignifying manner with chlorine and bleaching agents containing chlorine. However, these products were unable to satisfy the ever-increasing optical demands. In addition, environmental concerns about bleaching agents containing chlorine and chemical pulps containing chlorine led to a situation where industrial- level production of high-yield chemical pulps was not pursued. Furthermore, less expensive recycling paper has increasingly been used in paper production.
  • delignifying bleaching of chemical pulps often has the disadvantage that chemicals used for bleaching also attack cellulose fibers to a considerable extent, thus reducing the strength of chemical pulps.
  • US 4,634,499 and US 4,734,162 each relate to processes for preparing a chemical pulp from hardwood which is especially suitable for the preparation of tissue papers.
  • Pulping is carried out with ammonium sulfite, first at less than 110° C, then at a maximum temperature of 140° C to
  • EP 0 287 960 A relates to a process for preparing a hemicellulose hydrolysate and a special chemical pulp by a two-step process, wherein
  • a first step comprises pre-hydrolysis of the lignocellulosic materials, for example, with water, a mineral acid, sulfur dioxide, sulfite pulping liquor, and sulfite waste liquor, at a temperature of 100° to 180° C and over a hydrolysis period of 10 to 200 minutes, and
  • a second step in which the lignin contained in the pre-hydrolysed material is dissolved occurs by means of neutral sulfite pulping with addition of ant raquinone as the catalyst, the initial pH being at least 10.
  • the temperature is preferably 160° to 180° C and the treatment time 100 to 200 minutes.
  • the resulting ligno-cellulosic material is mechanically defibrated and optionally bleached.
  • Yields obtained in this manner range from 37.0 % to 45.7 : based on the wood used, the kappa number ranges from 17.2 to 48.1, and the degree of brightness (ISO value) at 48.2 to 87.1.
  • GB-1,546,877 B relates to a CTMP (chemo-thermomechanical pulp) which is suitable for absorbant products such as tissue paper, and, additionally, has a light color. Yields at
  • the production process comprises the following steps:
  • Suitable bleaching chemicals are alkali metal peroxides such as sodium peroxide or hydrogen peroxide, or reducing bleaching agents such as dithionite, hydroxyl amine, thiourea, or thioglycolic acid.
  • An essential feature of the resulting chemical pulp is a content of at least 10 % by weight of sulfonated fiber bundles, each consisting of two to four individual fibers.
  • EP 0 446 110 A describes a process for bleaching chemical pulps (yield ranges approx. 85 to 90 %) , which are obtained mechanically (mechanical pulp) , optionally combined with chemical methods (chemo echanical pulp) and/or thermal methods.
  • This bleaching process comprises the following steps: • pretreatment of (mechanical or chemomechanical) pulp with a complexing agent for metal ions followed by a washing step
  • this process produces degrees of brightness of 83.9% ISO.
  • Bleached mechanical pulps and bleached chemomechanical pulps have the further disadvantage of an unstable degree of brightness. This is due to the fact that the bleaching chemicals convert chromophoric groups of the lignin into non-chromophoric groups, which however are unstable. This type of reduction in the degree of brightness (discoloration) may be induced either by light or heat.
  • a disadvantage of known chemical pulps is their chlorine content and/or formation within the bleach of soluble reaction products containing chlorine, which is environmentally undesirable.
  • a further aspect of the invention is to make available a process for producing such pulp.
  • a further object of the present invention is to make available pulp based paper or nonwovens and/or products which are characterized by both resistance to mechanical stress and high quality of appearance.
  • a process for producing a chlorine-free bleached sulfite chemical pulp comprising the following steps: delignification of chips (commonly woodchips) from ligncellulosic material by a sulfite pulping process, in particular, in the presence of magnesium until the defibration point has been attained, and bleaching of the resulting fibrous material in a chlorine-free bleaching sequence comprising at least one bleaching step using an oxidizing agent in the presence of a base;
  • chlorine-free bleached chemical pulp obtainable by a sulfite pulping process followed by chlorine-free bleaching, characterized in that it has an ISO degree of brightness of at least 83 % and a strength, expressed as breaking length, of at least 6 km (measured according to Zellcheming V/12/57) , determined with a test sheet (ISO 5269-2, August 1998) produced from the pulp without beating the same, and • paper and nonwovens obtainable from this pulp.
  • chips from ligno-cellulosic material are partially delignified in a sulfite pulping process, in particular in the presence of magnesium, until the point of defibration of the material is attained.
  • the point of defibration is the point in time during the pulping at which the fibers subjected to chemical delignification may readily be separated into individual fibers without mechanical defibration. Once the point of defibrationhas been reached, the individual fibers are collected generally by pumping off the pulped lignocellulosic material out of the cooker.
  • the kappa value of the resulting pulp depends on the type of wood, the degree of pulping, as well as on the chemical system that was applied.
  • the partially delignified fibrous material obtained from the first step has a kappa value (according to DIN 54357, August 1978) of 50 to 75, in particular 60 to 70. This is the case, in particular, for spruce or pine.
  • One advantage of the sulfite process used according to the invention is that the point of defibration is obtained at considerably higher residual lignin contents and yields than in the sulfate pulping process. This is due to the fact that in the initial pulping phase, sulfite solutions prefer to dissolve lignin in the middle lamella of the wood cells, and thereby the bonding between the wood cells is lost. This results in a fiber surface of relatively low residual lignin content. The largest part of the yet remaining lignin is located in the central layer of the cell wall (S2) (on the structure of a wood cell, see e . g. Figure 20.2, page 509 in T.P. Nevell and S.
  • S2 central layer of the cell wall
  • the residual lignin content of the pulp resulting from the sulfite process in particular the acidic sulfite process has not only relatively few chromophoric groups, but it is also less condensed and therefore more reactive.
  • the term ""ligno-cellulosic material ' ' includes all materials containing cellulose and lignin as main components, typically wood.
  • the lignin content is generally at least 20 wt.-% (hardwood about 22 wt.%, conifers 27 - 33 wt.-%).
  • the cellulose content of wood is at least 40 wt.-%, generally 40 to 50 wt.-%.
  • suitable kinds of wood comprise spruce, pine, aspen, beech, birch, maple, poplar, and oak.
  • eucalyptus is especially suitable as a source of fibers for tissue papers .
  • the use of spruce and beech is especially preferred.
  • the ligno-cellulosic material used Prior to pulping, the ligno-cellulosic material used is roughly chopped into chips .
  • the size of the chips may vary and ranges for example from 1 to 5 cm in breadth and length, with a thickness of up to 1 cm.
  • Pulping (first step) is carried out with an acidic sulfite solution in a known manner, e . g. with an aqueous solution containing sulfite and/or bisulfite ions as well as sodium, potassium, magnesium, or ammonium ions. Suitable methods are described in depth in G. A. Smook, M. J. Kocurek, Handbook for Pulp and Paper Technologists, Tappi, Atlanta, 1982, pages 58 through 65.
  • the chemical pulping occurs in a single step, i.e. without sudden (as contrast to gradual) changes in conditions of the process such as pH. The entire pulping process does not require any additional mechanical means.
  • Chips of lignocellulosic material may be pulped in alkaline, neutral, or acidic conditions, however, preferably in an acidic environment with sulfite. Pulping at a pH of 1 to 5, especially 1.2 to 4.0 is particularly preferred.
  • pulping is performed with an aqueous solution containing sulfite and/or bisulfite ions as well as magnesium ions .
  • the pulping temperature preferably ranges from 130° to 165° C, in particular 135° to 150° C. Until a maximum temperature of 130° to 150° C is attained, heating should preferably be carried out over a period of 30 to 120 minutes .
  • the temperature is maintained at the maximum temperature preferably for a time period of 120 to 300 minutes.
  • a time period of 30 to 60 minutes is preferred for cooling from the maximum temperature (T max ) to room temperature .
  • Total pulping time (heating + pulping at T max + cooling) ranges preferably from 180 to 480 minutes.
  • the SO 2 content of the pulping solution relative to the dry weight (see Examples for its determination) of the lignocellulosic material used preferably equals 5 to 30 % by weight, in particular 15 to 24 % by weight.
  • pulping chemicals such as, for example, anthraquinone is not required, but may be used in alkaline sulfite pulping processes .
  • the lignocellulosic material-to-liquor ratio preferably ranges from 1:3 to 1:5, especially from 1:3.5 to 1:3.7, relative to the dry weight of the lignocellulosic material .
  • the first step of the pulping process according to the invention results in an unbleached chemical pulp (hereinafter also referred to as "fibrous material”), which is then transferred to the bleaching sequence.
  • fibrous material unbleached chemical pulp
  • the yield of unbleached chemical pulp relative to the dry weight of the ligno-cellulosic material used is greater than 50 % by weight, preferably at least 55 % by weight, for example, about 60 % by weight.
  • the degree of brightness of the material thus obtained is usually equal to 35 to 60 % ISO, preferably 40 to 55 % ISO.
  • the unbleached chemical pulp has the following strength parameters, each measured according to ISO 5269-2; August 1998, on test sheets having a basis weight of about 80 g/cm 2 using a standard climate according to DIN EN 20187 ( see description in the Examples) . All of the following values are based on unbeaten chemical pulp which corresponds to a freeness value (°SR, measured according to DIN-ISO 5267/1; March 1999) of approx. 12 to 15:
  • the sulfite pulping process used as the first step of the process of the invention has the advantage over the sulfate process of producing a pulp having a relatively light color even at higher residual lignin contents .
  • This intermediate which likewise is a part of the invention, as well as the process steps producing it, is then subjected to bleaching in one or more steps.
  • the chemical pulp resulting from the first stage is separated from the cooking liquor in a known manner, e . g. it may be filtered and optionally washed (usually with water) .
  • each bleaching sequence used according to the invention is bleaching with a chlorine- free oxidant, in the presence of a base in a so-called "first bleaching step".
  • the entire bleaching sequence is carried out with chlorine-free agents.
  • the terms ""chlorine-free bleaching sequence'' and “"chlorine-free bleaching chemicals ' ' mean that the bleaching chemicals contain no chlorine, neither elemental chlorine, nor bonded chlorine such as, e.g. in chlorine dioxide.
  • the entire bleaching sequence is preferably carried out without additional mechanical pulping means, i.e. defibration means .
  • the base used in the first bleaching step is preferably the same base that is used in pulping. This makes it easier to close water cycles, since the filtrate from the washer after the first bleaching step may be used for washing in the washer after the pulping step. Furthermore, by using the same base, preferably one containing magnesium, the resulting bleach waste liquors may be disposed together with the cooking waste liquors or at least partially recycled.
  • Sodium hydroxide, magnesium oxide (MgO) , and/or magnesium hydroxide ( g(OH)2) are preferred bases.
  • Hydrogen peroxide (H2O2) is a preferred oxidant.
  • the amount of oxidant is preferably 35 to 60 kg/t, in particular 40 to 55 kg/t, relative to the dry weight of the fibrous material used.
  • the amount of base used generally ranges from 10 to 20 kg/t relative to the dry weight of the fibrous material used.
  • the first bleaching step is preferably conducted at a temperature of 60° to 80° C.
  • the preferred pH range is from 8.5 to 9.5.
  • the duration of this bleaching step is preferably 240 to 420 minutes.
  • the effect of this first bleaching step may be intensified by using oxygen.
  • oxygen is used in an amount of
  • This first bleaching step is preferably combined with at least one other (so-called ""second'') bleaching step which is also conducted with an oxidant, in the presence of a base.
  • a peracetic acid step preferably in a pH range from 7 to 9
  • PAA peracetic acid
  • the preferred base is sodium hydroxide (NaOH) or magnesium oxide (MgO) (where hereinafter the term ""Magnesium oxide (MgO) ' ' also includes magnesium hydroxide (Mg(0H) 2 ) .
  • Both oxidant and base may be used in the same amounts set forth above. Duration and temperature of this bleaching step may also correspond to those of the first bleaching step.
  • the advantage of a peracetic acid step (magnesium oxide as base) as the second optional bleaching step is the fact that additional waste water cycles may be closed in order to minimize waste.
  • bleaching abilities may be improved by first treating the fibrous material with a complexing agent.
  • suitable complexing agents are nitrogen-containing organic compounds, in particular nitrogen-containing polycarboxylic acids, nitrogen-containing polyphosphonic acids, and nitrogen-containing polyalcohols .
  • nitrogen- containing polycarboxylic acids are diethylenetriamine pentaacetic acid (DTPA) , ethylenediamine tetraacetic acid (EDTA) , and nitrilo-triacetic acid (NTA) .
  • Diethylenetriamine pentamethylenephosphonic acid (DTPMPA) and diethylenetriamine pentaphosphonic acid are examples of nitrogen-containing poylphosphonic acids.
  • DTPMPA Diethylenetriamine pentamethylenephosphonic acid
  • diethylenetriamine pentaphosphonic acid are examples of nitrogen-containing poylphosphonic acids.
  • other complexing agents such as polycarboxylic acids, e . g. oxalic acid, citric acid or tartaric acid, or phosphonic acids.
  • Preferred complexing agents are: DTPA, DTPMPA, and EDTA.
  • complexing agent may be added in the amount of 0.5 to 3 kg/t relative to the fibrous material used.
  • the complexing treatment is performed at approx. 60° C.
  • the complexing treatment is carried out in a weakly acidic environment (hereinafter referred to as ⁇ Q M ).
  • an acidic wash or ""AQ"' one sets the pH of the pulp suspension at a value of 3 or less, e . g. by addition of H2SO 4 . In this manner, one may dissolve MgO that has precipitated onto the pulp or into the suspension. After setting the pH value, one adds the complexing agent to the suspension.
  • This form of complexing treatment is particularly suited as a first step of the bleaching sequence, or if it has been preceded by at least one bleaching step in the presence of MgO as base.
  • the second (optional) bleaching step may be followed by additional oxidizing bleaching steps with chlorine-free oxidants in the presence of base.
  • a third oxidizing bleaching step is preferably performed using hydrogen peroxide in the presence of sodium hydroxide as base. This third oxidizing bleaching step is preferably performed under the same conditions as those described in the first and second bleaching steps.
  • the oxidizing bleaching steps are preferably combined with a so-called ""reducing bleaching step'' using a reducing bleaching agent.
  • a reducing bleaching step concludes the entire bleaching sequence.
  • the bleaching sequence comprises a first oxidative bleaching step, followed by reducing bleaching step, and then an additional oxidative bleaching step .
  • Bleaching agents that are suitable for the reducing bleaching step include water-soluble dithionite salts, hydroxylamine, thiourea, thioglycolic acid, borohydride (e.g. sodium borohydride) , or formamidinosulfinic acid. Especially preferred is the use of formamidinosulfinic acid or dithionite, particularly sodium dithionite .
  • the amount of reducing agent used in the reducing bleaching step preferably ranges from 5 to 15 % by weight relative to the amount of fibrous material used. This reaction is to ) to to 1 l- 1
  • bleaching sequences 6 and 7 represent the best mode for practicing the invention.
  • This pulp has the properties of a chemical pulp that is obtained by a sulfite pulping process, in particular a magnesium (bi) sulfite process, and that is then bleached without the use of chlorine or chlorine-containing chemicals. It has a brightness of at least 83% ISO and is further characterized by a breaking length (dry) of at least 6 km, preferably at least 7 km, more preferred at least 8 km, in particular at least 9 km, e.g. 10 km [measured (according to Zellcheming V/12/57) on a test sheet made from unbeaten pulp (freeness of 12 to 15° SR measured according to DIN-ISO 5267/1; March 1999) basis weight of approx. 80 g/m 2 , produced according to ISO 5269-2; August 1998, in a standard climate according to DIN EN 20187; November 1993)] .
  • the degree of brightness is preferably at least 84 % ISO, particularly at least 85% ISO.
  • the degree of brightness may be 86 % ISO.
  • One advantage of the pulp according to the invention is that in contrast to mechanical pulp or chemomechanical pulp, its degree of brightness does not significantly decline during further processing.
  • the pulp according to the invention is substantially free of chlorine and/or chloride.
  • the pulp has an OX content of less than 30 mg/kg, or in particular, is free of OX.
  • the OX content relates to the residual halogen organic compounds in the pulp, which may essentially be formed during bleaching and are measured in accordance with DIN 38414/18 and PTS-RH012/90.
  • Pulp that is low in OX or is OX-free, and/or products derived from such pulp are more environmentally compatible than pulp and pulp-derived products containing OX. This also applies to the production process . In order to close water cycles as much as possible, it is likewise preferred that only chlorine-free chemicals be used in pulp production, because that way a build-up of chlorine, chloride, and/or chlorine-containing substances may be avoided.
  • (bleached, unbeaten) pulp according to the invention has
  • the (bleached) pulp according to the invention preferably has a very low fiber bundle content of bundles having at least two fibers, i.e. preferably less than 5 % by weight, in particular less than 1 % by weight relative to the dry weight. It is more preferred for it to be free of such bundles .
  • the pulp is ground following the bleaching sequence.
  • it has a freeness value of more than 15, in particular more than 15 and simultaneously not more than 18 °SR. With an increased freeness value there is an increase in breaking length.
  • This additional surface treatment (beating) which has a favorable effect on the strength properties of the resulting paper/tissue paper, may preferably be brought about within the pulp refinement system of a paper/tissue paper machine.
  • such surface treatment (beating) occurs as part of pulp production, i.e. while it is still at the pulp plant.
  • a refiner is particularly suitable for this purpose. Fibrillation of the surface occurs during mechanical treatment of the pulp/water suspension. This treatment influences the static and dynamic strength properties.
  • the fibers are shortened (cut) or are fibrillated, which includes the separation of the outer layers of the fiber wall, this latter process substantially increasing the surface and bonding capacity of the fibers .
  • the refiner operating mode associated with fibrillation is therefore preferred.
  • the residual lignin content of the bleached pulp according to the invention ranges preferably from 10 to 30, more preferred from 15 to 25, in particular from 18 to 22.
  • the process according to the invention thus makes it possible to a large extent to delignify lignocellulosic material without the aid of mechanical pulping means .
  • the average fiber length of the inventive bleached pulp ranges preferably from 1.8 to 2.2 mm (measured according to Kajaani using a Kajaani machine FS-200) .
  • the water retention capacity of the pulp according to the invention ranges preferably from 130 to 150 %, in particular from 140 to 145 % (measured according to Zellcheming IV/33/57, as described in the Examples) .
  • the present invention also relates to paper or nonwoven comprising the bleached pulp according to the invention, preferably in the amount of at least 50 % by weight, in particular at least 80 % by weight, relative to the dry weight of the finished product.
  • the paper can be a packaging paper, a graphic paper or tissue paper.
  • the paper is a tissue paper.
  • the tissue paper or nonwoven may be one-ply or multiple- ply.
  • Nonwovens may also be called textile-like composite materials, which represent flexible porous fabrics that are not produced by the classic methods of weaving warp and weft or by looping, but by intertwining and/or by cohesive and/or adhesive bonding of fibers which may for example be present in the form of endless fibers or prefabricated fibers of a finite length, as synthetic fibers produced in si tu or in the form of staple fibers.
  • the nonwovens according to the invention may thus consist of mixtures of synthetic fibers in the form of staple fibers and the pulp according to the invention.
  • Papers are also planar materials, albeit essentially composed of fibers of a plant origin and formed by drainage of a fibrous-material suspension on a wire or between two continuously revolving wires and by subsequent compression and drainage or drying of the thus produced fibrous mat ( cf. DIN 6730, May 1996) .
  • the standard restricts the range of mass per unit area (basis weight) for paper to a maximum of 225 g/m 2 . ) 00 t to H ⁇ >
  • tissue paper is to be made out of the pulp according to the invention, the process essentially comprises
  • the drying portion (TAD (through air drying) or conventional drying on the yankee cylinder) that also usually includes the crepe process essential for tissues,
  • Paper can be formed by placing the fibers, in an oriented or random manner, on one or between two continuously revolving wires of a paper making machine while simultaneously removing the main quantity of water of dilution until dry-solids contents of usually between 12 and 35 % are obtained.
  • Drying the formed primary fibrous web occurs in one or more steps by mechanical and thermal means until a final dry-solids content of usually about 93 to 97 %.
  • this stage is followed by the crepe process which crucially influences the properties of the finished tissue product in conventional processes.
  • the conventional dry crepe process involves creping on a usually 4.5 to 6 m diameter drying cylinder, the so-called yankee cylinder, by means of a crepe doctor with the aforementioned final dry-solids content of the raw tissue paper (wet creping can be used if lower demands are made of the tissue quality) .
  • the creped, finally dry raw tissue paper (raw tissue) is then available for further processing into the paper product or tissue paper product according to the invention. > ) to to M H
  • an intermediate step preferably occurs with so-called doubling in which the raw tissue in the finished product ' s desired number of plies is usually gathered on a common multiply master roll.
  • the processing step from the raw tissue that has already been optionally wound up in several plies to the finished tissue product occurs in processing machines which include operations such as repeated smoothing of the tissue, edge embossing, to an extent combined with full area and/or local application of adhesive to produce ply adhesion of the individual plies (raw tissue) to be combined together, as well as longitudinal cut, folding, cross cut, placement and bringing together a plurality of individual tissues and their packaging as well as bringing them together to form larger surrounding packaging or bundles .
  • the individual ' paper ply webs can also be pre-embossed and then combined in a roll gap according to the foot-to-foot or nested methods .
  • test sheets (having a basis weight of approx. 80 g/m 2 ) were made in accordance with ISO 5269-2: August 1998) .
  • the thus obtained test sheets were always conditioned for a duration of at least 12 hours in a standard climate at a temperature of (23 ⁇ 1) ° C and a relative humidity of (50 ⁇ 2)% in accordance with DIN EN 20187; November 1993, paper, cardboard and pulp, a standard climate for pretreatment and testing and a method of monitoring the climate and pretreatment of samples, November 1993 (see ISO 187 : 1990) .
  • the breaking length was determined using a dry test sheet produced according to 1) following a process described in Zellcheming V/12/1957.
  • Tear strength was determined according to Elmendorff using a test sheet produced according to 1) following a process described in DIN 53128.
  • the kappa number is determined according to DIN 54357 (August 1978)
  • the WRV is determined in the following way.
  • the principle of determining the WRV is based on centrifuging swollen pulp samples at room temperature in a special-purpose centrifuge beaker with 3000-fold gravitational acceleration.
  • the WRV in percent indicates the portion of water in the sample that cannot be centrifuged.
  • the tubes for the centrifuge inserts are filled to about 2/3 of the volume with the moist pulp sample without pressing firmly.
  • W the weight of the moist substance
  • D the dry weight of the substance
  • W minus D the weight of the absorbed water
  • Dry Weight The weight values that are given as ""dry weight'' relate to dried material, lignocellulosic material, pulp, paper, or nonwoven (product) that was dried at 105° C until constant weight was achieved.
  • the freeness value (in °SR) was measured according to DIN- ISO 5267/1; March 1999.
  • the degree of brightness (in %) was determined according to ISO following SCAN Cll:1975.
  • Pine chips of a width of 10 to 25 mm, a length of 13 to 35 mm and with a thickness of 1 to 10 mm were pulped in a magnesium bisulfite solution (free SO2 as hydrogen sulfite or sulfite-bound SO2) having a total SO2 content of 23.6 % by weight/wood (dry weight) and a magnesium content measured as MgO of 7 % by weight/wood (dry weight) at an initial pH of 1.7 and temperature of 138° C.
  • the wood-to- liquor ratio was 1:3.5.
  • the warming to the maximum temperature of 138°C took 30 minutes. The temperature was maintained at the maximum level for a total of 4.5 hours (270 minutes) . Once the defibration point was reached, cooling to room temperature required 60 minutes.
  • the resulting pulp was separated from waste liquor, washed with water, and dried, yielding 58.2 % (dry weight) relative to the wood used, at a kappa number of 52.2 and a degree of brightness of 46.1 % ISO.
  • the washed pulp subsequently was subjected to complexing treatment, being contacted at a temperature of 60° C for a period of 30 minutes with 2 kg/t of complexing agent DTPA at a density of 3 % (unless otherwise stated, the data given in kg/t in Examples 1 and 2 consistently refers to the dry weight of pulp) .
  • the pH value was set at 5.2 for the complexing treatment with H2SO 4 .
  • the pulp was bleached in aqueous solution containing 50 kg/t of hydrogen peroxide and 15 kg/t MgO (at a density of 10 %) for a reaction time of 360 minutes and at a reaction temperature of 70° C.
  • the resulting pulp was bleached for the last time, reduced with formamidinosulfinic acid (FAS) .
  • FAS formamidinosulfinic acid
  • 5 kg/t formamidinosulfinic acid was used at a temperature of 90° C and density of 10 % for a period of 60 minutes .
  • the degree of brightness of the resulting pulp was recorded at 85.9 % ISO.
  • the yield (dry weight) of the pulp obtained after the bleaching sequence was 95.2 % by weight relative to the dry weight of the pulp subjected to the bleaching sequence.

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Abstract

La présente invention concerne un procédé pour préparer de la pâte chimique à base de sulfite entièrement blanchie, qui comprend la délignification des copeaux d'une matière lignocellulosique selon un procédé de traitement de pâte à base de sulfite, jusqu'au défibrage de ladite matière, et le blanchiment de la matière fibreuse ainsi obtenue au moyen d'une séquence de blanchiment exempte de chlore. Le procédé comprend au moins une première étape de blanchiment avec un oxydant exempt de chlore, en présence d'une base. La pâte chimique préparée selon ce procédé et le papier ou le non-tissé fait à partir de ce matériau sont caractérisés par un degré élevé de luminosité (au moins 83 % ISO) et une résistance élevée.
PCT/EP2001/014103 2000-12-22 2001-12-03 Pate chimique entierement blanchie a base de sulfite, procede de fabrication et produits derives WO2002052101A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10064131.8 2000-12-22
DE2000164131 DE10064131C2 (de) 2000-12-22 2000-12-22 Vollgebleichter Sulfit-Zellstoff, Verfahren zu seiner Herstellung und daraus hergestellte Produkte

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WO2002052101A1 true WO2002052101A1 (fr) 2002-07-04

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PCT/EP2001/014103 WO2002052101A1 (fr) 2000-12-22 2001-12-03 Pate chimique entierement blanchie a base de sulfite, procede de fabrication et produits derives

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DE (1) DE10064131C2 (fr)
WO (1) WO2002052101A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1420109A1 (fr) * 2002-11-14 2004-05-19 Södra Cell AB Procédé et appareil pour le traitement de pâte papetière
WO2011127999A1 (fr) * 2010-04-14 2011-10-20 Voith Patent Gmbh Procédé de préparation d'une matière fibreuse de bois
WO2012037024A3 (fr) * 2010-09-16 2012-08-23 Georgia-Pacific Consumer Products Lp Pâtes de haute blancheur obtenues à partir de vieux papiers riches en lignine
EP3396063A1 (fr) * 2017-04-26 2018-10-31 ETH Zurich Procédé de production de matériau composite cellulosique densifié

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
DE102006061480A1 (de) * 2006-12-23 2008-06-26 Voith Patent Gmbh Verfahren zum Herstellen von Faserstoff
DE102007007654A1 (de) * 2007-02-13 2008-08-14 Voith Patent Gmbh FAS Bleiche
DE102007022752A1 (de) * 2007-05-11 2008-11-13 Voith Patent Gmbh Bleichen von lignocellulosischen Primärfasern

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GB1546877A (en) * 1975-11-13 1979-05-31 Mo Och Domsjoe Ab Highyield pulp suitable for absorbent products and processfor its manufacture
US4634499A (en) * 1983-05-02 1987-01-06 The Procter & Gamble Company Sulfite process for making pulp having a tactile softness from hardwood chips
EP0287960A2 (fr) * 1987-04-21 1988-10-26 SciTech Services, Inc. Procédé de fabrication d'un hydrolysat d'hémicellulose et une pâte spéciale
RU2164571C1 (ru) * 2000-06-27 2001-03-27 Камский целлюлозно-бумажный комбинат Способ получения беленой сульфитной целлюлозы на магниевом основании

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FR2659363B1 (fr) * 1990-03-07 1996-04-19 Atochem Procede de preparation de pates a haut rendement blanchies.
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GB1546877A (en) * 1975-11-13 1979-05-31 Mo Och Domsjoe Ab Highyield pulp suitable for absorbent products and processfor its manufacture
US4634499A (en) * 1983-05-02 1987-01-06 The Procter & Gamble Company Sulfite process for making pulp having a tactile softness from hardwood chips
EP0287960A2 (fr) * 1987-04-21 1988-10-26 SciTech Services, Inc. Procédé de fabrication d'un hydrolysat d'hémicellulose et une pâte spéciale
RU2164571C1 (ru) * 2000-06-27 2001-03-27 Камский целлюлозно-бумажный комбинат Способ получения беленой сульфитной целлюлозы на магниевом основании

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DATABASE WPI Section Ch Week 200134, Derwent World Patents Index; Class F09, AN 2001-326499, XP002192458 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1420109A1 (fr) * 2002-11-14 2004-05-19 Södra Cell AB Procédé et appareil pour le traitement de pâte papetière
WO2011127999A1 (fr) * 2010-04-14 2011-10-20 Voith Patent Gmbh Procédé de préparation d'une matière fibreuse de bois
WO2012037024A3 (fr) * 2010-09-16 2012-08-23 Georgia-Pacific Consumer Products Lp Pâtes de haute blancheur obtenues à partir de vieux papiers riches en lignine
US8845860B2 (en) 2010-09-16 2014-09-30 Georgia-Pacific Consumer Products Lp High brightness pulps from lignin rich waste papers
EP3396063A1 (fr) * 2017-04-26 2018-10-31 ETH Zurich Procédé de production de matériau composite cellulosique densifié
WO2018197222A1 (fr) * 2017-04-26 2018-11-01 Eth Zurich Procédé de production d'un matériau composite cellulosique densifié

Also Published As

Publication number Publication date
DE10064131A1 (de) 2002-07-25
DE10064131C2 (de) 2003-03-27

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