US20090266500A1 - Process for producing tissue paper - Google Patents

Process for producing tissue paper Download PDF

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Publication number
US20090266500A1
US20090266500A1 US12/432,919 US43291909A US2009266500A1 US 20090266500 A1 US20090266500 A1 US 20090266500A1 US 43291909 A US43291909 A US 43291909A US 2009266500 A1 US2009266500 A1 US 2009266500A1
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Prior art keywords
wood
fibrous material
chemicals
oven
digestion
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Abandoned
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US12/432,919
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English (en)
Inventor
Hans-Ludwig Schubert
Frank Peter Meltzer
Esa-Matti Aalto
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Voith Patent GmbH
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Voith Patent GmbH
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Priority claimed from DE200610061480 external-priority patent/DE102006061480A1/de
Priority claimed from DE200710017061 external-priority patent/DE102007017061A1/de
Application filed by Voith Patent GmbH filed Critical Voith Patent GmbH
Assigned to VOITH PATENT GMBH reassignment VOITH PATENT GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AALTO, ESA-MATTI, MELTZER, FRANK PETER, SCHUBERT, HANS-LUDWIG
Publication of US20090266500A1 publication Critical patent/US20090266500A1/en
Abandoned legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/002—Tissue paper; Absorbent paper
    • 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
    • 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
    • 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
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/14—Making cellulose wadding, filter or blotting paper
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/14—Making cellulose wadding, filter or blotting paper
    • D21F11/145—Making cellulose wadding, filter or blotting paper including a through-drying process
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
    • D21H11/06—Sulfite or bisulfite pulp

Definitions

  • the invention relates to a process for producing a tissue web, which is produced from a stock suspension including fibers.
  • the porosity and the permeability of the tissue paper are determined critically by the freeness of the fibers in the stock suspension from which the tissue paper is produced.
  • a high freeness causes a high water retention value for the fibers of the stock suspension, which means that the tissue paper is difficult to dewater during its production.
  • the tissue must be tear-resistant.
  • the tearing strength is determined both by the production process and by the freeness of the fibers.
  • the tissue paper In order to increase the tearing strength, the tissue paper must be consolidated during its production. In order to obtain a high tearing strength, the proportion of fines must also be high.
  • the fibers already exhibit high strength values at a freeness which is far lower as compared with fibers used hitherto.
  • the fibrous material according to the invention is already capable of forming good bonds with neighboring fibers at a lower freeness and therefore also with a lower expenditure of refining energy.
  • the lignin content of the unbleached fibrous material in the case of coniferous wood can advantageously include at least 15%, preferably at least 18%, in particular at least 21%, of the oven-dry fibrous material, in the case of deciduous wood at least 12%, preferably at least 14%, in particular at least 16%, of the oven-dry fibrous material and, in the case of annual plants, at least 10%, preferably at least 12% and in particular at least 19%, of the oven-dry fibrous material.
  • the tearing length for coniferous wood fiber stock at 12°SR should be greater than 7 km, preferably greater than 7.5 km and in particular greater than 8 km.
  • the tearing length for coniferous wood fiber stock at 15°SR should be greater than 9 km, preferably greater than 9.5 km and in particular greater than 10 km.
  • the tearing length for deciduous wood fiber stock at a lignin content of at least 12% and a freeness of 20°SR should be greater than 6 km, preferably greater than 7 km and in particular greater than 7.5 km.
  • the tearing length for annual plant fiber stock at 20°SR should be greater than 3.5 km, preferably greater than 4 km and in particular greater than 4.5 km.
  • the fibrous material according to the invention is not just distinguished by high tearing lengths. Instead, the strength level overall is high.
  • the fibrous material according to the invention is subjected to a bleaching treatment, the fiber properties are enhanced considerably.
  • the bleaching treatment is required for many applications with higher requirements on the whiteness. However, it is also aimed at the setting and improvement of the fiber properties. With the bleaching treatment, the tearing lengths increase.
  • the stock suspension should contain lignocellulosic fibrous material made of wood or annual plants which has a tearing length of more than 7.5 km at 15°SR and a lignin content of at least 13%, based on the oven-dry fibrous material, for coniferous wood in the bleached state, or a tearing length of more than 5.0 km at 20°SR and a lignin content of at least 10%, based on the oven-dry fibrous material, for deciduous wood in the bleached state, or a tearing length of more than 5.5 km at 20°SR and a lignin content of at least 10%, based on the oven-dry fibrous material, for annual plants in the bleached state.
  • the tearing length for coniferous wood fiber stock at 15°SR should be greater than 9 km, preferably greater than 10 km.
  • the tearing length for deciduous wood fiber stock at 20°SR should be greater than 5.5 km and the tearing length for annual plant fiber stock at 25°SR should be greater than 5 km, preferably greater than 5.5 km and in particular greater than 6 km.
  • the stock suspension should exclusively contain lignocellolosic fibrous material according to the above description.
  • the stock suspension is only partly formed from such lignocellulosic fibrous material.
  • tissue web Following the formation of a tissue web, this is preferably led between an upper structured and permeable belt and a lower permeable belt in a dewatering step, pressure being exerted on the upper belt, the tissue web and the lower belt along a dewatering section.
  • the pressure exerted on the arrangement including the upper belt, tissue web and lower belt can be effected by a gas flow and/or by a mechanical pressing force.
  • a gas flows firstly through the upper belt, then the tissue web and then the lower belt.
  • the dewatering takes place in the direction of the lower belt.
  • the arrangement including the upper belt, tissue web and lower belt is led in at least some sections between a press belt under tension and a smooth surface, the press belt acting on the upper belt and the lower belt being supported on the smooth surface.
  • the gas flow flows through the arrangement including the upper belt, tissue web and lower belt, at least in some sections in the region of the dewatering section, so that the dewatering is carried out simultaneously by the pressing force of the press belt and the through-flow of the gas.
  • the press belt should be under a tension of at least 30 kN/m, preferably at least 60 kN/m and in particular 80 kN/m.
  • the press belt In order to be able to achieve good dewatering of the tissue web by way of the mechanical tension of the press belt and also on account of the gas flow through the press belt, the press belt should have an open area of more than 50% and a contact area of at least 15%.
  • the smooth surface is preferably formed by the circumferential surface of a roll.
  • the gas flow can advantageously be produced via a suction zone in the roll and/or a positive pressure hood arranged above the upper belt.
  • the lignocellulosic fibrous material it is important that at least a proportion of the stock suspension is produced from wood or annual plants having a lignin content of at least 15% for coniferous wood and 12% for deciduous wood and 10% for annual plants, in each case based on the oven-dry fiber mass, by the following steps:
  • the process according to the invention is based on the fact that, in order to produce high-yield fibrous materials, higher quantities of chemicals are used than were previously usual. More than 5% of chemicals for coniferous wood is considerably above the quantities of chemicals previously usual for industrial fibrous material production, likewise more than 3.5% of chemicals for deciduous wood and 2.5% for annual plants. This high use of chemicals produces fibrous materials with good yield and excellent strength properties. Thus, for coniferous wood at freenesses of only 12°SR to 15°SR, tearing lengths of more than 8 km but also tearing lengths of more than 9 km and more than 10 km are measured. For deciduous woods at only 20°SR, values of more than 5 km but also tearing lengths of more than 6 km and more than 7 km are measured. The desired high strength level is therefore achieved.
  • Fibrous materials according to the prior art do not exhibit an acceptable strength level at freenesses of 12°SR to 15°SR for coniferous wood fibrous materials or of 20°SR for deciduous wood.
  • Known fibrous materials at these low freenesses have until now resulted in fibers which have not demonstrated adequate strength properties for economic use of such fibers.
  • Suitable annual plants are in particular bamboo, hemp, rice straw, bagasse, wheat, miscanthus and the like.
  • the fibrous materials produced by the process of the invention already have tearing lengths of more than 8 km up to 11 km and tear propagation resistances of more than 70 cN up to more than 110 cN, based on a sheet weight of 100 g/m2.
  • These low freenesses are moreover achieved with a low specific requirement for refining energy, which is less than 500 kWh/t of fibrous material for coniferous wood; in the case of deciduous wood the need for refining energy can even be less than 300 kWh/t of fibrous material.
  • Deciduous wood fibrous materials having a lignin content of more than 14%, preferably more than 16%, particularly preferably more than 18%, and also annual plants having a lignin content of more than 10%, preferably more than 12%, in particular more than 19%, can likewise be produced with the process according to the invention and exhibit a high strength level.
  • the composition of the chemical solution used for the digestion can be defined in accordance with the wood or annual plants used for the digestion and the desired fibrous material properties.
  • a sulfite component is used.
  • a sulfide component can also be added. Digestion with a sulfite component is not disrupted by the presence of sulfide components.
  • sodium sulfite is normally used but the use of ammonium or potassium sulfite or of magnesium bisulfite is also possible.
  • an acid and/or an alkaline component can also be metered in.
  • the alkaline component used is normally sodium hydroxide (NaOH).
  • NaOH sodium hydroxide
  • carbonates is also possible, in particular sodium carbonate. All statements relating to quantities of chemicals in the digestion process in this document, for example to total chemical used or to the subdivision of the sulfite component and the alkaline component are, if not otherwise specified, in each case calculated and stated as sodium hydroxide (NaOH).
  • Acids can be metered in as acid components in order to set the desired pH. However, preference is given to the addition of SO2, if appropriate in aqueous solution. It is inexpensive and easily available, in particular when the used chemical solution, for example based on sodium sulfite, is conditioned for further use following the digestion.
  • the duration of the digestion for example during the production of coniferous wood fibrous materials, can be shortened by more than a half, depending on the digestion conditions by more than three-quarters. This noticeable effect is achieved with minimal use of quinone, for example.
  • a use of, for example, anthraquinone which is between 0.005% and 0.5% is optimal.
  • a use of anthraquinone of up to 1% also produces the desired effect.
  • a use of more than 3% anthraquinone is normally uneconomic.
  • a chemical solution is produced from an individual chemical or a plurality of the aforementioned chemicals.
  • An aqueous solution is normally added.
  • organic solvents can also be provided.
  • Alcohol in particular methanol and ethanol, in a mixture with water gives particularly effective chemical solutions for the production of high-quality high-yield fibrous materials.
  • the mixture ratio of water and alcohol can be optimized for the respective raw material in a few trials.
  • the quantity of chemicals to be used according to the invention for producing a fibrous material with a yield of at least 70% is at least 5% for coniferous wood, at least 3.5% for deciduous wood and at least 2.5% for annual plants, in each case based on the oven-dry wood or annual plant mass to be digested.
  • the quality of the fibrous material produced exhibits the best results with a chemical usage of up to 15% for coniferous wood, of up to 10% for deciduous wood and up to 10% for annual plants.
  • the use of the chemicals is somewhat lower, preferably between 4% and 10%, particularly preferably between 6% and 9%, and between 3% and 10% in the case of annual plants.
  • a ratio between an alkaline component and sulfur dioxide (SiO2) can be set over a wide range.
  • SO2 is named as representing the acid component mentioned above. It is therefore also possible to use an acid instead of SO2. Since the quinone component possibly added is used only in minimal quantities, normally considerably below 1%, it can be disregarded in setting this ratio.
  • a ratio of alkaline component:SO2 in a range from 5:1 to 1.6:1 is well suited to carrying out the process of the invention and to achieving fibrous materials with high strength properties.
  • a usual, particularly suitable range lies between 2:1 and 1.6:1.
  • the proportional components are coordinated on the basis of the raw material to be digested and the respectively chosen process management (digestion temperature, digestion time, impregnation).
  • the process according to the invention can be carried out in a wide pH range.
  • the ratio of alkaline component to acid component and the use of an acid or alkaline component can be set in such a way that at the start of the process a pH between 6 and 11, preferably between 7 and 11, particularly preferably between 7.5 and 10, is set.
  • the rather alkaline pH values between 8 and 11, which are advantageous for the process according to the invention, also encourage the action of the quinone component.
  • the process according to the invention is tolerant with respect to the pH; few chemicals are needed for pH adjustment. This has a beneficial effect on the costs for chemicals.
  • a pH between 5 and 9, normally between 6.5 and 9, for example for coniferous wood is established in the free-flowing chemical solution at the end of the digestion and also in the organic components dissolved therein, which are liquefied by the digestion.
  • the dissolved organic substances primarily include lignosulfates.
  • the mixing or impregnation of the wood or annual plant material to be digested is preferably carried out at elevated temperatures. Heating the chips and the chemical solution to up to 110° C., preferably to up to 120° C., particularly preferably to up to 130° C., leads to rapid and uniform digestion of the wood.
  • a time period of up to 30 minutes, preferably of up to 60 minutes, particularly preferably of up to 90 minutes, is advantageous. The respectively optimal time period depends, amongst other things, on the quantity of chemicals, the liquor ratio, the chosen temperature and the type of digestion (liquid or vapor phase).
  • the digestion of the lignocellulosic material mixed or impregnated with the chemical solution is preferably carried out at temperatures between 120° C. and 190° C., preferably between 140° C. and 180° C.
  • digestion temperatures between 150° C. and 170° C. are set.
  • Higher or lower temperatures can be set but in this temperature range the expenditure of energy for the heating and the acceleration of the digestion are in an economic relationship with each other.
  • Higher temperatures can additionally have a detrimental effect on the strengths and the whiteness of the fibrous materials.
  • the pressure generated by the high temperatures can readily be absorbed by appropriate design of the digester.
  • the duration of the heating is normally only a few minutes, normally up to 30 minutes, advantageously up to 10 minutes, in particular when steam heating is used.
  • the duration of the heating can be up to 120 minutes, preferably up to 60 minutes, for example when digestion in the liquid phase is carried out and the chemical solution has to be heated together with the chips.
  • the duration of the digestion is primarily chosen on the basis of the desired fibrous material properties.
  • the duration of the digestion can be shortened to up to 2 minutes, for example for the case of vapor-phase digestion of deciduous wood having a low lignin content. However, it can also be up to 180 minutes, if for example the digestion temperature is low and the natural lignin content of the wood to be digested is high. Even if the initial pH of the digestion is in the neutral range, a long digestion time can be necessary.
  • the digestion time is up to 90 minutes, particularly in the case of coniferous wood.
  • the digestion time is particularly preferably up to 60 minutes, advantageously up to 30 minutes. A digestion time of 60 minutes is suitable in particular in the case of deciduous woods.
  • the digestion time is up to 90 minutes.
  • a quinone component in particular anthraquinone, permits a reduction in the digestion time of up to 25% of the time required without the addition of anthraquinone. If the use of quinone components is omitted, the digestion time for comparable digestion results is lengthened by more than an hour, for example from 45 minutes to 180 minutes.
  • the duration of the digestion is set as a function of the chosen liquor ratio.
  • the chemical consumption is registered as the quantity of chemicals which—based on the quantity of chemicals originally used—is measured after the removal or separation of the chemical solution and, if appropriate, the capture of chemical solution which is measured after the difibering or in conjunction with capture of the chemical solution.
  • the chemical consumption depends on the absolute quantity of chemicals used for the digestion, based on the oven-dry mass of wood to be digested. The higher the use of digestion chemicals, the lower the direct conversion of chemicals. Given a use of 27.5% of chemicals, based on oven-dry mass of wood, for example only about 30% of the chemicals used are consumed. Given the use of 15% of chemicals, based on oven-dry mass of wood, 60% of the chemicals used are consumed, however, as could be verified in laboratory trials.
  • the chemical consumption of the process according to the invention according to a preferred embodiment of the process during the digestion is up to 80%, preferably up to 60%, particularly preferably up to 40%, advantageously up to 20%, particularly advantageously up to 10%, of the chemical input at the start of the digestion.
  • the chemical consumption for producing a tonne of fibrous material is around 6% to 14% sulfite and/or sulfide component and also alkaline and/or acid component and also, if appropriate, quinone component, based on oven-dry fibrous material (deciduous and coniferous wood or annual plants).
  • this quantity of chemicals is enough to produce a fibrous material having the prescribed properties.
  • it may prove to be expedient to use higher quantities of chemicals for the digestion for example the aforementioned up to 30% of chemicals based on oven-dry wood or annual plant mass.
  • the composition of the chemical solution removed is captured and subsequently adjusted to a prescribed composition for renewed use for the production of fibers.
  • the chemical solution which is removed before or after the digestion of the wood or the annual plants no longer has the composition set at the beginning. At least part of the chemicals used for the digestion has—as described above—penetrated into the material to be digested and/or has been consumed in the digestion. The unused chemicals can readily be used again for the next digestion.
  • the invention proposes firstly determining the composition of the chemicals removed and then supplementing the used proportions of, for example, sulfite, alkaline component, quinone component or else water or alcohol, in order once more to produce the prescribed composition of the next digestion.
  • This supplementation step is also designated strengthening.
  • the chemical solution in the case of removal before the digestion but also in the case of removal after the digestion, really contains no substances at all or very few substances which prove to be disruptive during renewed use of the strengthened chemical solution for the next digestion.
  • the process according to the invention which is based on making a surplus of digestion chemicals available during the impregnation, is also able to operate extremely economically, despite the procedure of the high chemical use, initially appearing uneconomic, for the removal or the separation and the strengthening of the chemical solution can be carried out simply and cost-effectively.
  • the process according to the invention is controlled specifically in such a way that only as little as possible of the starting material used is broken down or dissolved.
  • the aim is to produce a fibrous material which, for coniferous wood, has a lignin content of at least 15%, based on the oven-dry fiber mass, preferably a lignin content of at least 18%, particularly preferably of 21%, advantageously of at least 24%.
  • the aim is to achieve a lignin content of at least 12%, based on the oven-dry fiber mass, preferably of at least 14%, particularly preferably of at least 16%, advantageously of at least 18%.
  • the preferred lignin content is between 10 and 28%, in particular between 12 and 26%.
  • the yield of the process according to the invention is at least 70%, preferably more than 75%, advantageously more than 80%, in each case based on the wood used. This yield correlates with the lignin content of the fibrous material specified above.
  • the original lignin content of wood is specific to the type.
  • the loss of yield in the present process is predominantly represented as a loss of lignin.
  • the proportion of hydrocarbons is increased considerably, for example because digestion chemicals also put cellulose or hemicelluloses into solution in a manner that is undesired per se.
  • a further, advantageous measure, after the defibering and possibly the refining of the lignocellulosic material, is to remove the chemical solution still remaining and to supply it to further use.
  • this further use can include two aspects. Firstly, the organic material broken down or put into solution during the partial digestion, predominantly lignin, can be used further. For example, it is burned in order to obtain process energy. Or it is prepared in order to be used in a different manner. Secondly, the used and unused chemicals are reconditioned, so that they can be used for a renewed partial digestion of lignocellulosic material. This includes the preparation of consumed chemicals.
  • the chemical solution employed is used extraordinarily efficiently.
  • the fibrous material is washed, in order to displace the chemical solution as far as possible by way of water.
  • the filtrate arising during this washing and displacement operation contains considerable quantities of chemical solution and organic material.
  • this filtrate is supplied to the removed or separated chemical solution before the chemical solution is strengthened and fed to the next digestion.
  • the chemicals contained in the filtrate and organic constituents do not disrupt the digestion. To the extent that they make a contribution to the delignification during the next digestion, their content of chemicals is registered and taken into account during the determination of the quantity of chemicals needed for this digestion.
  • the chemicals further contained in the filtrate behave inertly during the impending digestion; they do not interfere.
  • the organic constituents contained in the filtrate likewise behave inertly. They are used further during the conditioning of the chemical solution after the next digestion, either to produce process energy or in another way.
  • FIG. 1 shows an apparatus for carrying out the inventive method
  • FIG. 2 shows a second apparatus.
  • the acid-soluble lignin was determined in accordance with TAPPI UM 250 .
  • the pH at the start of the digestion was adjusted to pH 8.5-9 by adding SO2.
  • the birch wood/chips mixture impregnated with chemical solution was heated to 170° C. over a time period of 90 minutes and digested at this maximum temperature over 60 minutes.
  • the free-flowing liquid was then removed by centrifuging, collected and analyzed and strengthened in an arrangement for feeding back unused liquid and in this way conditioned for the next digestion.
  • the digested chips were defibered. Partial quantities of the fibrous material produced in this way were refined for different times in order to determine the strength at different freenesses. The expenditure of energy for defibering the partly digested chips was less than 300 kWh/t of fibrous material.
  • the yield in this trial was around 77%, based on the wood mass used.
  • the whiteness is unexpectedly high with values over 55% ISO and thus offers a good starting basis for possible subsequent bleaching, in which whitenesses of 75% ISO can be achieved.
  • a refining time of 20 to 30 minutes is needed. Up to a refining time of 20 minutes (freeness 12°SR-15°SR), the freeness develops within a narrow range irrespective of the pH at the start of the digestion (pH 6 to pH 9.4).
  • the fibrous material was produced from birch chips, the pH at the start of the digestion being 9.4.
  • the digestion time was 60 minutes.
  • the digestion time can be reduced from about 180 minutes to 60 minutes under otherwise unchanged digestion conditions. This time gain is valuable, above all because the fibrous material production plants can be dimensioned smaller. Further potential savings reside in the fact that the temperature needed for the digestion has to be maintained over only a very much shorter time period.
  • the apparatus for providing a stock suspension which is used below in the process according to the invention for producing a tissue web includes a pulper, in which the dry raw and semifinished materials and waste paper are slushed in water and transformed into a state that can be pumped. The stock formed in this way is then fed to a mixing chest.
  • the stock suspension emerging from the headbox 13 has a freeness of less than 20°SR and a tearing length of more than 4.5 km.
  • the side of the structured belt 3 pointing toward the tissue web 1 has deepened regions and regions elevated with respect to the deepened regions, so that the tissue web 1 is formed in the deepened regions and the elevated regions of the structured belt 3 .
  • the difference in height between the deepened regions and the elevated regions is preferably between 0.07 mm and 0.6 mm.
  • the area formed by the elevated regions is preferably 10% or more, particularly preferably 20% or more and particularly preferably 25% to 30%.
  • the arrangement including upper belt 3 , tissue web 1 and forming fabric 14 is deflected around a forming roll 15 and the tissue web 1 is dewatered substantially by the forming fabric 14 , before the forming fabric 14 is taken off the tissue web 1 and the tissue web 1 is transported onward on the belt 4 .
  • the voluminous sections of the tissue web 1 formed in the deepened regions of the belt 3 have a higher volume and a higher grammage than the sections of the tissue web 1 formed in the elevated regions of the belt 3 .
  • the tissue web 1 already has a 3 dimensional structure.
  • the sheet formation can also take place between two smooth forming fabrics 14 , so that a substantially smooth tissue web 1 without a 3 dimensional structure is formed.
  • the tissue web 1 is led between the structured belt 3 , which is arranged on the top, and a lower, permeable belt 2 formed as a felt, pressure being exerted on the structured belt 3 , the tissue web 1 and the belt 2 along a dewatering section during the dewatering step, in such a way that the tissue web 1 is dewatered in the direction of the belt 2 , as indicated by the arrows in the two figures.
  • the pressure for dewatering the tissue web 1 during the dewatering step according to FIG. 1 is produced simultaneously, at least in some sections, by a gas flow and by a mechanical pressing force.
  • the gas flow is produced by a suction zone 10 in the roll 5 , the suction zone 10 having a length in the range between 200 mm and 2500 mm, preferably between 800 mm and 1800 mm, particularly preferably between 1200 mm and 1600 mm.
  • the vacuum in the suction zone 10 is between ⁇ 0.2 bar and ⁇ 0.8 bar, preferably between ⁇ 0.4 bar and ⁇ 0.6 bar.
  • the smooth surface is formed by the circumferential surface of the roll 5 .
  • the dewatering section 11 is defined substantially by the wrap region of the press belt 4 around the circumferential surface of the roll 5 , the wrap region being defined by the spacing of the two deflection rollers 12 .
  • the press belt 4 is under a tension of at least 30 kN/m, preferably at least 60 kN/m or 80 kN/m, and has an open area of at least 25% and a contact area of at least 10% of its total area pointing toward the upper belt 3 .
  • the press belt 4 embodied as a spiral link fabric, has an open area of between 51% and 62% and a contact area of between 38% and 49% of its total area pointing toward the upper belt 3 .
  • the tissue web 1 leaves the dewatering section 11 with a dryness of between 25% and 55%.
  • the tissue web 1 is then led through a press nip, the tissue web 1 in the press nip being arranged between the structured belt 3 and a smooth roll surface of a Yankee drying cylinder 7 .
  • the press nip is an extended press nip formed by the Yankee drying cylinder 7 and a shoe press roll 8 .
  • the tissue web 1 rests on one side with a relatively great area on the circumferential surface of the Yankee drying cylinder 7 , the tissue web 1 resting on the structured belt 3 on the other side.
  • the deepened regions and the regions elevated relative thereto of the structured belt 3 are here formed and arranged in relation to one another in such a way that the voluminous sections are substantially not pressed in the press nip. On the other hand, the other sections are pressed, by which way the strength of the tissue web 1 is increased further.
  • a further dewatering step can be provided, which can be carried out by way of an apparatus 9 .
  • tissue web 1 before it runs through the press nip, to be led together with the structured belt 3 around an evacuated deflection roll, the structured belt 3 being arranged between the tissue web 1 and the evacuated deflection roll (not illustrated).
  • the gas flow can additionally be produced by a positive pressure hood 6 arranged above the structured belt 3 , the dewatering step in this case being carried out without any mechanical pressing force, i.e., as opposed to FIG. 1 , no press belt 4 which wraps around some section of the roll 5 being provided.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
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US12/432,919 2006-12-23 2009-04-30 Process for producing tissue paper Abandoned US20090266500A1 (en)

Applications Claiming Priority (5)

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DE200610061480 DE102006061480A1 (de) 2006-12-23 2006-12-23 Verfahren zum Herstellen von Faserstoff
DE102006061480.1 2006-12-23
DE102007017061.2 2007-04-11
DE200710017061 DE102007017061A1 (de) 2007-04-11 2007-04-11 Verfahren zur Herstellung von Tissuepapier
PCT/EP2007/010165 WO2008077450A1 (de) 2006-12-23 2007-11-23 Verfahren zur herstellung von tissuepapier

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PCT/EP2007/010165 Continuation WO2008077450A1 (de) 2006-12-23 2007-11-23 Verfahren zur herstellung von tissuepapier

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EP (1) EP2126195A1 (pt)
JP (1) JP2010514946A (pt)
BR (1) BRPI0718883A2 (pt)
CA (1) CA2673175A1 (pt)
RU (1) RU2009128370A (pt)
WO (1) WO2008077450A1 (pt)

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EP2758593A4 (en) * 2011-09-21 2015-04-29 Kimberly Clark Co WIPING PAPER PRODUCT COMPRISING BAMBOO
US10577748B2 (en) 2015-04-29 2020-03-03 Essity Hygiene And Health Aktiebolag Tissue paper comprising pulp fibers originating from miscanthus and method for manufacturing the same
US11053643B2 (en) 2017-02-22 2021-07-06 Kimberly-Clark Worldwide, Inc. Layered tissue comprising non-wood fibers
US11441271B2 (en) * 2018-02-05 2022-09-13 Domtar Paper Company Llc Paper products and pulps with surface enhanced pulp fibers and increased absorbency, and methods of making same
US11473245B2 (en) 2016-08-01 2022-10-18 Domtar Paper Company Llc Surface enhanced pulp fibers at a substrate surface
US11499269B2 (en) 2016-10-18 2022-11-15 Domtar Paper Company Llc Method for production of filler loaded surface enhanced pulp fibers
US11608596B2 (en) 2019-03-26 2023-03-21 Domtar Paper Company, Llc Paper products subjected to a surface treatment comprising enzyme-treated surface enhanced pulp fibers and methods of making the same

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CN102154899B (zh) * 2011-04-28 2012-05-23 永州湘江纸业有限责任公司 一种砂纸原纸及其生产方法
CN105297526B (zh) * 2015-11-03 2017-05-24 山东鲁南新材料股份有限公司 一种耐水砂纸原纸及其生产方法
WO2020229737A1 (en) * 2019-05-15 2020-11-19 Kemira Oyj Fiber formulation, its use and method for making it

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Publication number Priority date Publication date Assignee Title
EP2758593A4 (en) * 2011-09-21 2015-04-29 Kimberly Clark Co WIPING PAPER PRODUCT COMPRISING BAMBOO
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US11473245B2 (en) 2016-08-01 2022-10-18 Domtar Paper Company Llc Surface enhanced pulp fibers at a substrate surface
US11499269B2 (en) 2016-10-18 2022-11-15 Domtar Paper Company Llc Method for production of filler loaded surface enhanced pulp fibers
US11053643B2 (en) 2017-02-22 2021-07-06 Kimberly-Clark Worldwide, Inc. Layered tissue comprising non-wood fibers
US11634870B2 (en) 2017-02-22 2023-04-25 Kimberly-Clark Worldwide, Inc. Layered tissue comprising non-wood fibers
US11441271B2 (en) * 2018-02-05 2022-09-13 Domtar Paper Company Llc Paper products and pulps with surface enhanced pulp fibers and increased absorbency, and methods of making same
US11608596B2 (en) 2019-03-26 2023-03-21 Domtar Paper Company, Llc Paper products subjected to a surface treatment comprising enzyme-treated surface enhanced pulp fibers and methods of making the same

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EP2126195A1 (de) 2009-12-02
JP2010514946A (ja) 2010-05-06
WO2008077450A1 (de) 2008-07-03
BRPI0718883A2 (pt) 2014-02-18
CA2673175A1 (en) 2008-07-03
RU2009128370A (ru) 2011-01-27

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