EP3289140A1 - Papier pour sac brun désintégrable - Google Patents

Papier pour sac brun désintégrable

Info

Publication number
EP3289140A1
EP3289140A1 EP15813459.3A EP15813459A EP3289140A1 EP 3289140 A1 EP3289140 A1 EP 3289140A1 EP 15813459 A EP15813459 A EP 15813459A EP 3289140 A1 EP3289140 A1 EP 3289140A1
Authority
EP
European Patent Office
Prior art keywords
paper
less
pulp
sack
ton
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP15813459.3A
Other languages
German (de)
English (en)
Inventor
Grete ANDERSSON ÅVITSLAND
Camilla RENNEL WENNBERG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Billerud AB
Original Assignee
Billerudkorsnas AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Billerudkorsnas AB filed Critical Billerudkorsnas AB
Publication of EP3289140A1 publication Critical patent/EP3289140A1/fr
Pending legal-status Critical Current

Links

Classifications

    • 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
    • D21H27/10—Packing paper
    • 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
    • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/005—Mechanical treatment
    • 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
    • D21H11/08—Mechanical or thermomechanical pulp
    • 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
    • D21H11/10—Mixtures of chemical and mechanical pulp
    • 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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
    • D21H17/24—Polysaccharides
    • D21H17/28—Starch
    • 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
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • 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
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/16—Sizing or water-repelling agents
    • 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
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/32—Bleaching agents
    • 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
    • D21H11/04—Kraft or sulfate pulp

Definitions

  • the present disclosure relates to the field of sack paper and the production thereof.
  • Kraft paper is a suitable sack wall material.
  • the sacks typically have two or more walls, i.e. layers of paper material, to further strengthen the sack
  • a wall layer of a sack is often referred to as a ply.
  • Production of ply material is for example disclosed in WO 99/02772.
  • a charged polymer e.g. starch
  • a charged polymer e.g. starch
  • GB2448486 discusses a dissolvable bag made from paper or another soluble materials, to contain building materials requiring mixing, such as cement, lime or plaster. It is stated that the dissolvable bag can be directly added to the mixer where the bag rapidly dissolves when water is added, which reduces spillage, wastage, mess and exposure to the building products. The packs are placed together in a waterproof wrapping to ensure the product stays dry whilst stored or in transit.
  • WO 2004052746 suggests spray or dip-coating the whole exterior of already filled bags with a non-permeable, waterproof coating.
  • WO 2004052746 fails to device any materials for the inner and outer layer of the bag.
  • US 2011/0315272 states that a sack that dissolves in a moist environment can be obtained by using a dextrin adhesive for gluing the folded ends of the sack. Folding and gluing patterns for the ends are also discussed. A moisture barrier in the sack is not discussed.
  • JP5085565A suggests that a cement sack that can be added directly to a mixer is composed of a water-soluble material, such as PVOH, having a thickness of 20-70 ⁇ .
  • FR2874598 discloses a similar solution.
  • Brown (i.e. unbleached) sack paper is often stronger than white (i.e.
  • brown paper may be preferred over white paper as the bleaching process may be associated with significant costs and environmental concerns. Further, bleaching may lower the yield.
  • the present inventors have addressed the need for a disintegratable brown sack paper, i.e. a paper for a sack that can be added together with its contents, such as cement, to a mixer and then disintegrates in the mixer.
  • brown prior art sack papers such as the brown sack paper produced according to WO 99/02772 or the brown qualities of BillerudKorsnas' commercial sack paper QuickFill®, are not sufficiently disintergratable.
  • the inventors have found that the disintegratability of a brown sack paper can be significantly improved by adding bleached pulp to the unbleached pulp used for manufacturing the brown sack paper.
  • the inventors have also found that the disintegratability of a brown sack paper can be significantly improved by reducing the Kappa number and the degree of LC refining of the unbleached pulp used for manufacturing the brown sack paper.
  • the Gurley porosity (ISO 5636-5) of the sack paper is less than 20 s, such as less than 15 s, such as less than 10 s, such as less than 8 s, such as less than 7 s, such as less than 6 s.
  • the ISO brightness (ISO 2470-1) of the bleached pulp is at least 60, such as at least 70, such as at least 80, such as at least 85.
  • the Kappa number (SCA -C 1:00) of the unbleached pulp is less than 70, such as less than 60, such as less than 55, such as less than 50, such as less than 40, such as less than 35.
  • the ISO brightness (ISO 2470-1) of sack paper is less than 30, such as less than 25, such as less than 22.
  • ratio of unbleached pulp to bleached pulp in the pulp mixture is between 6:1 and 1:1, such as between 5:1 and 1:1, such as between 4:1 and 1:1, such as between
  • the geometric tensile energy absorption index (ISO 1924-3) of the sack paper is at least 2 J/g, such as at least 2.4 J/g, such as at least 2.8 J/g, such as at least 3.2 J/g.
  • the grammage (ISO 536) of the sack paper is 50-140 g/m 2 , such as 60-120 g/m 2 , such as 60- 110 g/m 2 , such as 70-110 g/m 2 , such as 75-100 g/m 2 .
  • the unbleached pulp is a chemical pulp, such as a Kraft pulp.
  • the bleached pulp is a chemical pulp, such as a Kraft pulp.
  • delignification has a Kappa number (SCAN-C 1:00) below 60, such as below 45, such as 20-40.
  • bleaching process comprises alkaline hydrogen peroxide bleaching and/or peracetic acid (PAA) bleaching.
  • PAA peracetic acid
  • step b) comprises creping.
  • 0.3 kg/ton paper of hydrophobic size is added. 28. The method of any one of the preceding items, wherein starch is added in an amount of 1-7 kg/ton paper, such as 1-5 kg/ton paper, such as 2-5 kg/ton paper.
  • a sack paper having a Gurley porosity (ISO 5636-5) of less than 25 s composed of a mixture of unbleached fibers and bleached fibers, wherein the dry weight ratio of unbleached fibers to bleached fibers in the mixture is between 7:1 and 1:1.
  • the sack paper of any one of items 29-35 obtained from a papermaking process in which less than 2 kg/ton paper of hydrophobic size was added.
  • the sack paper of any one of items 29-37 obtained from a papermaking process in which less than 1.0 kg/ton paper of hydrophobic size was added.
  • the sack paper of any one of items 29-38 obtained from a papermaking process in which less than 0.5 kg/ton paper, such as less than 0.3 kg/ton paper, of hydrophobic size was added.
  • a sack for a hydraulic binder, such as cement, comprising a ply composed of the sack paper according to any one of items 29-41.
  • the multiple-ply sack according to item 43 further comprising an outer ply composed of a white sack paper.
  • the multiple-ply sack according to item 43 further comprising an outer ply composed of the sack paper according to any one of items 29-41.
  • the sack according to any one of items 42-46 containing a hydraulic binder, such as cement.
  • a method of producing a hydraulic composition comprising adding water and the sack according to any one of items 47-48 to a mixer and allowing the ply material of the sack to disintegrate during mixing in the mixer.
  • the amount of starch added in the method is 1-7 kg/ton paper and the amount of hydrophobic size added in the method is less than 2 kg/ton.
  • the method of item 50, wherein the Gurley porosity (ISO 5636-5) of the sack paper is less than 20 s, such as less than 15 s, such as less than 10 s, such as less than 8 s, such as less than 7 s, such as less than 6 s.
  • any one of items 50-53, wherein the grammage (ISO 536) of the sack paper is 50-140 g/m 2 , such as 60-120 g/m 2 , such as 60-110 g/m 2 , such as 70-110 g/m 2 , such as 75-100 g/m 2 .
  • the pulp provided in step a) is a chemical pulp, such as a Kraft pulp.
  • step a) The method of any one of items 50-55, wherein at least 50 %, such as at least 60 %, 70 %, 80 % or 90 %, of the dry weight of the pulp provided in step a) is softwood pulp.
  • step c) comprises creping
  • any one of items 50-57, wherein the amount of hydrophobic size is less than 1.5 kg/ton paper, such as less than 1.0 kg/ton paper, such as less than 0.5 kg/ton paper, such as less than 0.3 kg/ton paper, such as o kg/ton paper.
  • step a) comprises conversion of wood into a pulp having a Kappa number (SCAN-C 1:00) of 25- 40 using Kraft pulping.
  • a "sack paper” is a paper that is intended for a paper sack, such as a paper sack for a hydraulic binder.
  • the hydraulic binder of the present disclosure is for use in a hydraulic composition. Examples of hydraulic compositions are discussed below.
  • the paper sack should vent air during filling.
  • the sack paper of the present disclosure which is primarily intended for an inner ply, but also can be used for an outer ply, has a lower air resistance (or a higher porosity) than many other types of paper.
  • the sack comprising the sack paper of the first aspect is normally a valve sack.
  • Gurley is a measurement of the time (s) taken for 100 ml of air to pass through a specified area of a paper sheet. Short time means highly porous paper.
  • the sack paper of the present disclosure has a Gurley porosity (ISO 5636-5) of less than 25 s. Preferably, it is less than 20 s. In some embodiments, it is lower than 15 s, such as lower than 10 s, such as lower than 8 s, 7 s or 6 s.
  • a sack paper having a Gurley porosity below 2 or 3 s often has an insufficient strength. Therefore, the Gurley porosity of the sack paper of the present disclosure is preferably at least 2 or 3 s. In some embodiments, it is at least 4 s.
  • Typical Gurley porosity ranges for the present disclosure are thus 3-15 s, preferably 4-10 s, such as 4-8 s, 4-7 s or 4-6.5 s.
  • the method of the first aspect comprises the step of:
  • the unbleached pulp is preferably a chemical pulp.
  • the reason for selecting a chemical pulp is that it generally results in stronger paper than recycled pulp or mechanical pulp.
  • the chemical pulp may for example be Kraft pulp or sulfite pulp. Kraft pulp is the most preferred option. As well known by the skilled person, Kraft pulp is produced by the Kraft process.
  • a chemical pulp contains much less lignin than mechanical pulps.
  • a chemical pulp may contain less than 5 % lignin before bleaching, compared to about 30 % for a mechanical pulp. The inventors have found that a reduction in lignin content generally improves the disintegratability.
  • the Kappa number of the unbleached chemical pulp may for example be 45- 60.
  • a benefit of preparing a pulp having such a relatively high Kappa number is a relatively high yield.
  • a relatively low Kappa number (i.e. 20-45) of the unbleached pulp may also allow for a relatively low proportion of bleached pulp in the pulp mixture, i.e. a ratio between 7:1 and 1.5:1.
  • the Kappa number may be measured according to SCAN-C 1:00 or ISO 302:2004.
  • the bleached pulp is chemical pulp, such as Kraft pulp or sulfite pulp.
  • chemical pulp such as Kraft pulp or sulfite pulp.
  • the Kappa number of the bleached pulp is preferably less than 10, such as less than 7, such as less than 4, such as less than 2.
  • the inventors believe that, at least to some extent, lower Kappa numbers in the bleached pulp are associated with an increased disintegratability of the final sack paper.
  • the brightness of a pulp is a measure of the degree of bleaching. As for the Kappa number, the inventors believe that, at least to some extent, higher brightness of the bleached pulp is associated with an increased
  • the ISO brightness (ISO 2470-1) of the bleached pulp may thus be at least 60, for example. It may be preferred if the ISO brightness of the bleached pulp is at least 70. In some embodiments, it may be at least 80 or 85. From an economical and environmental perspective it may however be preferred not to bleach as far as to an ISO brightness of 80 or 85. Accordingly, in some embodiments, the ISO brightness is less than 85, such as 50-80.
  • a sheet is formed from the bleached pulp to facilitate the measurement of its ISO brightness.
  • the unbleached pulp and/or the bleached pulp of the present disclosure may comprise at least 50 % (based on dry weight) softwood pulp.
  • the proportion of softwood pulp may for example be at least 75 % or 90 % (based on dry weight) of the unbleached pulp and/or the bleached pulp.
  • the method of the first aspect may further comprise a bleaching process to prepare the bleached pulp.
  • a bleaching process may for example comprise oxygen delignification.
  • the oxygen delignification may for example be the first step of the bleaching process. Accordingly, pulp from a cooking process maybe subjected to the oxygen delignification. Such pulp, which leaves the cooking process and is subjected to the oxygen delignification, may for example have a Kappa number below 45, such as 20-40 before the oxygen delignification.
  • the cooking process used in the preparation of the bleached pulp may for example result in a lower Kappa number than the cooking process used in the preparation of the unbleached pulp.
  • the same cooking process is used in the preparation of both pulps.
  • the bleaching process may comprise one of more of the following steps (which are all well known to the skilled person) :
  • PAA peracetic acid bleaching
  • the bleaching process comprises O and at least two or three of D, Z, E, P, PAA and Y.
  • the pulps i.e. the unbleached pulp and the bleached pulp
  • the pulps are mixed in such proportions that the dry weight ratio of unbleached pulp to bleached pulp in the pulp mixture is between 7:1 and 1:1, preferably between 6:1 and 1:1, such as between 5:1 and 1:1, such as between 4:1 and 1:1, such as between 3.5:1 and 1.1:1, such as between 3:1 and 1.2:1, such as between 2.8:1 and 1.3:1. If the proportion of bleached pulp is too low, the disintegratability of the resulting paper will be too low. If however the proportion of bleached pulp is too high, the production costs may be too high.
  • the method of the first aspect further comprises the step of:
  • Step b) forming the sack paper from said pulp mixture.
  • Step b) usually comprise the normal operations for forming a paper from a pulp, such as forming a web on a wire in a wire section, pressing the web in a press section and drying the web in a drying section.
  • the sack paper obtained in step b) is still considered to be brown sack paper. Accordingly, the ISO brightness of the sack paper is preferably less than 30, such as less than 25, such as less than 22.
  • Paper properties of sack paper are often measured in the machine direction (MD) and in the cross direction (CD), since there may be significant differences in the properties, depending on the orientated fibre flow out of the headbox on the paper machine.
  • the index of a certain property is calculated by dividing the actual value by the grammage for the paper in question.
  • the grammage (sometimes referred to as basis weight) is measured by weight and surface area, e.g. according to ISO 536.
  • the tensile strength is the maximum force that a paper will withstand before breaking. In the standard test ISO 1924-3, a stripe of 15 mm width and 100 mm length is used with a constant rate of elongation. The tensile strength is one parameter in the measurement of the tensile energy absorption (TEA). In the same test, the tensile strength, the stretch and the TEA value are obtained.
  • TEA tensile energy absorption
  • TEA is sometimes considered to be the paper property that best represents the relevant strength of the paper sack wall. This is supported by the correlation between TEA and drop tests. By dropping a sack the filling goods will move when reaching the floor. This movement strains the sack wall. To withstand the strain, the TEA should be high, which means that a
  • the grammage (ISO 536) of the sack paper of the present disclosure is normally in the range of 50 to 140 g/m 2 . Generally, it is preferred to add another paper ply in a sack instead of increasing the grammage of a ply above 140 g/m 2 .
  • the grammage (ISO 536) of the sack paper of the present disclosure is 50-130 g/m 2 , such as 60-120 g/m 2 , such as 60-110 g/m 2 , such as 70-110 g/m 2 , such as 75-100 g/m 2 .
  • the geometric TEA index (ISO 1924-3) of the sack paper of the present disclosure is preferably at least 2 J/g.
  • it may be at least 2.4 J/g, such as at least 2.8 J/g, such as at least 3.2 J/g.
  • Creping of paper improves stretchability and thereby the TEA index.
  • step b) comprises creping
  • the disintegratability may be improved by decreasing the amount of hydrophobic size, such as alkylketene dimer (AKD), alkyl succinic anhydride (ASA) and/or rosin size, added in the method.
  • the amount of hydrophobic size added in the process is less than 2 kg/ton paper.
  • the amount may be less than 1.5 kg/ton paper, such as less than 1 kg/ton paper, such as less than 0.5 kg/ton paper, such as less than 0.3 kg/ton paper.
  • no hydrophobic size is added in the method.
  • the disintegratability may be improved by minimizing the amount of starch.
  • the amount of starch added in the process is less than 7 kg/ton paper, such as less than 5 kg/ton paper, such as less than 4 kg/ton paper.
  • the minimum amount of starch added may for example be at least 1 kg/ton paper, such as at least 2 kg/ton paper, such as at least 3 kg/ton paper.
  • starch comprises starch of any charge.
  • the starch is preferably added before step b).
  • "kg/ton paper” refers to kg per ton of dried paper from the paper making process. Such dried paper normally has a dry matter content (w/w) of 90-95 %.
  • a sack paper having a Gurley porosity (ISO 5636-5) of less than 25 s composed of a mixture of unbleached fibers and an bleached fibers, wherein the dry weight ratio of unbleached fibers to bleached fibers in the mixture is between 7:1 and 1:1.
  • the sack paper of the second aspect may be manufactured using the method of the first aspect. Accordingly, the embodiments and examples of the first aspect apply mutatis mutandis to the second aspect.
  • a sack for a hydraulic binder such as cement, comprising a ply composed of the sack paper of the second aspect.
  • the sack of the present disclosure is normally a valve sack.
  • the sack may for example be a multiple-ply sack comprising an inner ply composed of the sack paper according to the second aspect.
  • each paper ply may for example have a grammage of 50-100 g/m 2 , such as 60-90 g/m 2 .
  • the multiple-ply sack may further comprise an outer ply composed of a white sack paper.
  • a white sack paper for the purpose is described in the patent application EP14175729.4.
  • a white sack paper comprises a moisture barrier coating.
  • Various moisture barriers are known to the skilled person.
  • the coat weight of the moisture barrier coating may for example be 5-30 g/m 2 .
  • the moisture barrier properties may be considered to be sufficient when the water vapor transmission rate (WVTR, ISO 2528, measured at 38 °C and 90 % relative humidity (tropic climate)) is less than 1400 g/m 2 *24h, preferably less than 1200 g/m 2 *24h.
  • the WVTR of sack paper comprising a moisture barrier may be 700-1200 g/m 2 *24h.
  • the white sack paper forming the outer ply is disintegratable, also when it is provided with a moisture barrier coating.
  • An example of such a coated paper is described in the patent application EP14175736.9.
  • the sack may comprise a top end formed by folding and gluing the ply material such that a portion of the top end is not sealed by the gluing.
  • the folding and gluing is such that air may escape through the non-sealed portion during filling of the sack with the hydraulic binder.
  • such a sack is designed such that air penetrates the innermost ply and then escapes through the non-sealed portion during filling at high throughput rates.
  • the multiple-ply sack may comprise an outer ply composed of the sack paper according to the second aspect.
  • all plies of the multiple-ply sack may be composed of sack paper according to the second aspect. From an economical perspective, it is beneficial if all the paper needed for a sack can be produced with a single paper making process.
  • the volume of the sack of the present disclosure may for example be 8-45 liters, such as 15-45 liters.
  • the sack of the present disclosure may for example contain a hydraulic binder, such as cement.
  • the amount of the hydraulic binder may for example be 20-60 kg.
  • 25 kg, 35 kg and 50 kg sacks are demanded on the market and may be prepared according to the present disclosure.
  • the dimensions of a filled 25 kg sack may for example be 400x450x110 mm.
  • a "25 kg sack" typically can be filled with about 17.4 liters of material, while a "50 kg sack” is typically can be filled with about 35 liters of material.
  • sacks comprise a plastic film arranged between two paper plies of the sacks.
  • a film which normally is composed of polyethylene, is often referred to as a "free film".
  • a plastic free film disintegrates poorly in a cement l8 mixer. Hence it is preferred that the sack of the present disclosure does not comprise a plastic free film.
  • a method of producing a hydraulic composition comprising adding water and a sack according to the present disclosure to a mixer and allowing the ply material of the sack to disintegrate during mixing in the mixer.
  • the hydraulic composition is thus a mix comprising the hydraulic binder and water (often referred to as mixing water).
  • the composition may for example further comprise one or more aggregates, one or more additives and/or one or more mineral additions.
  • An example of an aggregate is sand, which may have different particle sizes.
  • the hydraulic composition of the present disclosure is preferably a cement slurry, a mortar, a concrete, a plaster paste or a slurry of hydraulic lime.
  • the hydraulic composition is selected from a cement slurry, a mortar and a concrete.
  • bleached fibers are not necessarily mixed with unbleached fibers.
  • the production of a disintegratable sack paper is based on a pulp having a Kappa number that is relatively low compared to many unbleached pulps. Furthermore, the addition of starch, the addition of hydrophobic size and LC refining are kept at relatively low levels.
  • the "low Kappa pulp” may be obtained by mixing unbleached pulp with bleached pulp as in the first aspect or by a cooking process that is designed to produce the "low Kappa pulp". For example, the duration or residence time of a cooking process may be adapted to obtain an unbleached pulp having the desired Kappa number (as mentioned above, longer cooking times generally results in lower Kappa numbers). Also, oxygen delignification may be used to reduce the Kappa number below 25 or 30.
  • a method of manufacturing a sack paper having a Gurley porosity (ISO 5636-5) of less than 25 s comprising the steps of:
  • the amount of starch added in the method is 1-7 kg/ton paper and the amount of hydrophobic size added in the method is less than 2 kg/ton.
  • HC refining is typically carried out at a fibre suspension consistency of 15% by weight or higher, such as i5%-45% by weight.
  • LC refining is typically carried out at a fibre suspension consistency of 10% by weight or lower, such as 2%-io%.
  • the energy supply in the HC refining may be between 100 and 320 kWh/ ton paper, preferably between 150 and 300 kWh/ ton paper, such as between 170 and 300 kWh/ton paper.
  • the energy supply is less than 120 kWh per ton paper (such as 10-120 kWh per ton paper) if LC refining is carried out.
  • the energy supply of the LC refining is less than 110 kWh per ton paper, such as 10-110 kWh per ton paper, and more preferably less than 100 kWh per ton paper, such as 10-100 kWh per top paper.
  • the Gurley porosity (ISO 5636-5) of the sack paper of the fourth aspect is preferably less than 20 s, such as less than 15 s, such as 10 s or less. In some embodiments, it is even less than 8 s, such as less than 7 s, such as less than 6 s.
  • Step a) preferably comprises Kraft pulping, which means the Kraft pulping is used for converting wood into the pulp having a Kappa number (SCAN-C 1:00) of 25-40.
  • a Kappa number SCAN-C 1:00
  • at least 50 % by dry weight of the wood used in such Kraft pulping is softwood. More preferably, at least 60 %, 70 %, 80 % or 90 %, of the dry weight of the wood is softwood.
  • the pulping may be combined with subsequent oxygen delignification.
  • the Kappa number (SCAN-C 1:00) of the pulp provided in step a) is 20-35. The skilled person knows how to adjust a cooking process to obtain such a Kappa number.
  • the amount of hydrophobic size added in the method of the fourth aspect is preferably less than 1.5 kg/ton paper, such as less than 1.0 kg/ton paper, such as less than 0.5 kg/ton paper, such as less than 0.3 kg/ton paper. In one embodiment, addition of hydrophobic size is completely omitted in the method.
  • the amount of starch is preferably kept relatively low to improve the disintegratability. At the same time, the strength of the resulting paper may be too low if starch is completely omitted. Therefore, the amount of starch added in the method of the fourth aspect is preferably 1-5 kg/ton paper, such as 2-5 kg/ton paper.
  • Fig 1 is a plot showing the disintegratability of various papers.
  • Both pulps were softwood kraft pulps subjected to HC refining (about 120 kWh/ton) and LC refining (20 kWh/ton), to which starch (8 kg/ton), Fennosil 517 (0.25 kg/ton) and ASA size (1 kg/ton) had been added .
  • the Kappa number (SCAN-C 1:00) of the unbleached pulp was 50.
  • the ISO brightness (ISO 2470-1) of the bleached pulp was 90.
  • the laboratory trial set-up was first evaluated and found to have a sufficient correlation with the full scale trial.
  • bleached and unbleached pulps were obtained from paper mills.
  • the unbleached pulp was unbleached softwood kraft pulp subjected to HC refining (250 kWh/ton) and LC refining (18 kWh/ton).
  • the Kappa number (SCAN-C 1:00) of the unbleached pulp was 50.
  • the bleached pulp was bleached softwood kraft pulp subjected to HC refining (150 kWh/ton) and LC refining (16 kWh/ton).
  • the ISO brightness (ISO 2470-1) of the bleached pulp was 90.
  • Different pulps for sheet forming were prepared according to table 2 below. Laboratory sheets having a grammage of 80 g/m 2 were prepared in a dynamic sheet former according to BillerudKorsnas' internal method. The disintegratability of the sheets, which is also shown in table 2 below, was tested as in the full scale trial described above. Table 2.
  • the unbleached pulp and the bleached pulp were the same as in trial 1 with the exception that for the unbleached pulp, the degree of HC refining was 258 kWh/ton and the degree of LC refining was 41 kWh/ton.
  • Different pulps for sheet forming were prepared according to table 3 below.
  • Fennosil 517 (kg/ton) was added in an amount of 0.25 kg/ton.
  • No ASA was added in trial 2.
  • Laboratory sheets having a grammage of 80 g/m 2 were prepared in a dynamic sheet former according to BillerudKorsnas' internal method. The disintegratability of the sheets, which is also shown in table 3 below, was tested as in the full scale trial described above.
  • UDP unbleached pulp (wt.%).
  • BP bleached pulp (wt.%).
  • S starch (kg/ton).
  • D refers to
  • Trials 3 and 4 In trial 3, the unbleached pulp was unbleached softwood kraft pulp subjected to 177 kWh/ton HC refining and 131 kWh/ton LC refining. In trial 4, the unbleached pulp was the same type of unbleached softwood kraft pulp subjected to 210 kWh/ton HC refining and 95 kWh/ton LC refining. The Kappa number (SCAN-C 1:00) of the unbleached pulp was 30 in both trial 3 and trial 4. The bleached pulp was the same as in trial 1.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)

Abstract

La présente invention concerne un procédé de fabrication d'un papier pour sac présentant une porosité de Gurley (Norme ISO 5636-5) inférieure à 25 s, comprenant les étapes consistant à : a) mélanger une pâte à papier non blanchie avec une pâte à papier blanchie pour obtenir un mélange de pâte à papier dans des proportions telles que le rapport en poids sec de la pâte à papier non blanchie à la pâte à papier blanchie dans le mélange de pâte à papier soit compris entre 7:1 et 1:1 ; et b) former le papier pour sac à partir dudit mélange de pâte à papier, de l'amidon étant ajouté dans une quantité de 1-7 kg/tonne de papier.
EP15813459.3A 2015-04-29 2015-12-22 Papier pour sac brun désintégrable Pending EP3289140A1 (fr)

Applications Claiming Priority (2)

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EP15165614.7A EP3088606A1 (fr) 2015-04-29 2015-04-29 Papier d'ensachage brun désintégrable
PCT/EP2015/080949 WO2016173684A1 (fr) 2015-04-29 2015-12-22 Papier pour sac brun désintégrable

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EP3289140A1 true EP3289140A1 (fr) 2018-03-07

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EP15813459.3A Pending EP3289140A1 (fr) 2015-04-29 2015-12-22 Papier pour sac brun désintégrable

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EP (2) EP3088606A1 (fr)
CA (1) CA2982799A1 (fr)
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WO (1) WO2016173684A1 (fr)

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PL2963178T3 (pl) * 2014-07-04 2016-12-30 Wytwarzanie papieru workowego
EP3795745B1 (fr) * 2019-09-20 2024-10-23 Mondi AG Papier kraft ainsi que sac en papier fabriqué en papier kraft
JP6939976B1 (ja) * 2020-05-27 2021-09-22 王子ホールディングス株式会社 ヒートシール紙、包装袋
FR3113070A1 (fr) * 2020-07-30 2022-02-04 Vicat Papier et sac d’emballage, déperlants, destinés au conditionnement de produits divers
EP4101979A1 (fr) * 2021-06-10 2022-12-14 Mondi AG Papier d'emballage, ainsi que son procédé de fabrication

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Publication number Publication date
US20180230653A1 (en) 2018-08-16
RU2017134882A (ru) 2019-05-29
WO2016173684A1 (fr) 2016-11-03
RU2691364C2 (ru) 2019-06-11
RU2017134882A3 (fr) 2019-05-29
EP3088606A1 (fr) 2016-11-02
CA2982799A1 (fr) 2016-11-03

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