EP3184694A1 - Regendichter papiersack - Google Patents

Regendichter papiersack Download PDF

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Publication number
EP3184694A1
EP3184694A1 EP15201668.9A EP15201668A EP3184694A1 EP 3184694 A1 EP3184694 A1 EP 3184694A1 EP 15201668 A EP15201668 A EP 15201668A EP 3184694 A1 EP3184694 A1 EP 3184694A1
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EP
European Patent Office
Prior art keywords
paper
sack
ply
coating layer
layer
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.)
Withdrawn
Application number
EP15201668.9A
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English (en)
French (fr)
Inventor
Ove LINDSTRÖM
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.)
Billerudkorsnas 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
Priority to EP15201668.9A priority Critical patent/EP3184694A1/de
Priority to FIEP16825737.6T priority patent/FI3394342T3/fi
Priority to EP16825737.6A priority patent/EP3394342B1/de
Priority to PCT/EP2016/082115 priority patent/WO2017108910A1/en
Publication of EP3184694A1 publication Critical patent/EP3184694A1/de
Withdrawn legal-status Critical Current

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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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/675—Oxides, hydroxides or carbonates
    • 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
    • D21H19/00—Coated paper; Coating material
    • D21H19/36—Coatings with pigments
    • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
    • 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
    • D21H19/00—Coated paper; Coating material
    • D21H19/80—Paper comprising more than one coating
    • D21H19/82—Paper comprising more than one coating superposed
    • 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
    • D21H19/00—Coated paper; Coating material
    • D21H19/80—Paper comprising more than one coating
    • D21H19/84—Paper comprising more than one coating on both sides of the substrate
    • 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
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30—Multi-ply

Definitions

  • the present disclosure relates to a rainproof paper sack suitable for a hydraulic binder, such as cement, as well as a sack paper for use as the outer ply of such a rainproof sack.
  • the paper sacks need to hold a considerable material weight, i.e. have high tensile strength.
  • 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 construction.
  • a wall layer of a sack is often referred to as a ply. Production of ply material (i.e. sack paper) is for example disclosed in WO 99/02772 .
  • a material such as cement is sensitive to moisture contamination during storage.
  • cement sacks often require a protection against atmospheric water vapor penetration through the sack plies.
  • a moisture barrier incorporated as an intermediate layer in the sack, i.e. between two plies of the paper material.
  • the moisture barrier is typically a plastic film ("free film"), e.g. of polyethylene (PE), that is impermeable to water.
  • the free film may also improve resistance to grease and prevent contamination by microorganisms.
  • the paper sack should vent air during filling.
  • the air that accompanies the powdered material shall efficiently vent from the sack as the filling machines that delivers the material run at high throughput rates.
  • the venting capability of the sack is the actual limiting factor for the filling rate.
  • Efficient venting also prevents air from being trapped in the sack. Such trapped air may otherwise cause under-weight packs, sack rupture and problems when sacks are stacked for transportation.
  • the "venting” is also referred to as "deaeration”.
  • An object of the present discloure is to provide a sack that is rainproof and still meet other requirements of the sack industry. Examples of such other requirements are strength (to prevent rupture during handling), deaeration during filling (to allow high filling rates) and cost efficiency.
  • Another object of the present disclosure is to provide a sack paper for use as the outermost ply of the rainproof sack.
  • a multi-ply sack comprising an inner paper ply and an outer paper ply, wherein the outer paper ply comprises a paper layer that is sized with at least one hydrophobic size. Further and the outside of the sized paper layer is provided with a pre-coating layer and a barrier coating layer.
  • the outside of the outer paper ply is exposed to the surroundings, which means that the outside of the outer paper ply can be exposed to rain.
  • Bleached paper is generally significantly less hydrophobic than unbleached paper. Accordingly, bleached/white sack paper has higher water absorptiveness and is more sensitive to rain. Therefore, it is more challenging to develop a rainproof sack having a bleached outer paper ply than a rainproof sack having an unbleached outer paper ply.
  • sacks having white outer plies are demanded on the marked, also for sacks that may be exposed to rain.
  • the concept of the present disclosure is thus particularly beneficial when the sized paper layer of the outer paper ply is bleached.
  • the brightness of the sized paper layer may for example be at least 78 % or at least 80 % according to ISO 2470-1. Preferably, it is at least 83 %.
  • the total amount of hydrophobic size used for sizing the sized paper layer may for example be 1.5-4.0 kg/ton paper, such as 2.0-3.5 kg/ton paper.
  • the sizing technique may be internal sizing, which means that the size is added in the wet end of the paper machine, or surface sizing, which means that the size is applied to the paper surface after initial drying.
  • Examples of hydrophobic sizes are alkylketene dimer (AKD), alkenylsuccinic anhydride (ASA) and rosin size, which are all commercially available papermaking chemicals. The inventor has found that AKD and ASA reduce the water absorptiveness more efficiently than rosin size.
  • the added amount of AKD may be 0.4-1.4 kg/ton paper and preferably 0.5-1 kg/ton paper.
  • the added amount of rosin size may be 1.2-4.2 kg/ton paper and preferably 1.5-3 kg/ton paper.
  • the weight ratio of AKD to rosin size may be between 1:6 and 1:1.5.
  • the weight ratio is between 1:5 and 1:2 and more preferably between 1:4 and 1:2.5.
  • 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 %.
  • Alum may also be added to the pulp, e.g. in an amount of 0.5-5 kg/ton paper.
  • the addition of alum is particularly beneficial when the hydrophobic size comprises rosin size.
  • Alum refers to hydrated potassium aluminium sulphate (potassium alum).
  • the Cobb value represents the amount of water absorbed by a paper surface in a given time. Consequently, the hydrophobic sizing reduces the Cobb value of the sized paper layer.
  • Two examples of Cobb values are Cobb 60 s and Cobb 1800 s, wherein the absorption of water is measured after 60 seconds and 1800 seconds (30 minutes), respectively.
  • the Cobb 1800 s value measured according to ISO 535 of the outside of the sized paper layer may for example be less than 60 g/m 2 . Preferably it is less than 50 g/m 2 and more preferably less than 45 g/m 2 or less than 40 g/m 2 .
  • a typical lower limit for the Cobb 60 s value may be 25 or 30 g/m 2 .
  • a preferred range for the Cobb 1800 s value is thus 25-50 g/m 2 .
  • the Cobb 60 s value measured according to ISO 535 of the outside of the sized paper layer may for example be less than 30 g/m 2 . Preferably it is less than 25 g/m 2 .
  • a typical lower limit for the Cobb 60 s value may be 10 or 15 g/m 2 .
  • a preferred range for the Cobb 60 s value is thus 15-25 g/m 2 .
  • the sizing merely reduces water absorption. It does not completely prevent it. Therefore, the sized paper layer is provided the barrier coating layer (further discussed below).
  • the sack of the first aspect may lack a plastic film arranged between the outer paper ply and the inner paper ply.
  • a plastic film which is also referred to as a "free film”
  • the pre-coating layer is provided between the sized paper layer and the barrier coating layer.
  • a purpose of the pre-coating layer is to even the surface of the sized paper layer and thus reduce the amount of barrier material needed to form an efficient barrier coating layer. This is particularly beneficial when the sized paper layer is creped.
  • the pre-coating layer comprises a high amount of (relatively cheap) inorganic filler.
  • the pre-coating layer comprises a binder to hold the pre-coating layer together and bind it to the sized paper layer.
  • the binder and the inorganic filler are provided in a dry weight ratio of between 10:100 and 50:100 (sometimes referred to as between 10 and 50 parts).
  • the pre-coating layer comprises binder and inorganic filler in a dry weight ratio of between 15:100 and 40:100.
  • the most preferred dry weight ratio is between 20:100 and 35:100.
  • a benefit of a relatively high proportion of binder i.e. ⁇ 20 parts) is that the pre-coating better contributes to the overall barrier properties of the outer paper ply.
  • the filler and the binder are preferably the main components of the pre-coating layer.
  • the inorganic filler normally accounts for at least 70 % of the dry weight of the pre-coating layer.
  • the particles of the inorganic filler are relatively large.
  • Coarser particles means lower specific surface area, which in turn means that the binder in the pre-coating can form a more robust film.
  • the coarser particles do not negatively affect the printing properties as a barrier coating covers the pre-coating.
  • filler products with coarser particles are generally cheaper.
  • Yet other benefits of coarser particles is that they result in a pre-coating layer that better cover the surface and better prevents formation of blade scratches during blade coating of a barrier layer comprising platy clay than a pre-coating layer with finer particles.
  • the particle size of filler and pigment is often expressed as the weight proportion of particles having a particle size below 2 ⁇ m.
  • the value (% ⁇ 2 ⁇ m) is often measured using the particle size analyzer SediGraph 5100 (micromeritics®).
  • the particle size value (% ⁇ 2 ⁇ m) is generally above 80.
  • the particle size value (% ⁇ 2 ⁇ m) of the inorganic filler of the present disclosure is preferably 80 or lower, such as between 50 and 80.
  • the particle size value (% ⁇ 2 ⁇ m) is between 50 and 75, such as between 55 and 75.
  • the inorganic filler may for example comprise or consist of CaCO 3 pigment. Other types of filler are generally more expensive.
  • the binder of the pre-coating can for example be starch or rubber, such as a synthetic rubber. Rubber is preferred as it makes a contribution to the water barrier properties of the outer paper ply.
  • the rubber may for example be a synthetic rubber, preferably styrene-butadiene rubber.
  • the synthetic rubber is normally provided in the form of a water dispersion, normally referred to as latex.
  • Examples of other (optional) components of the pre-coating layer are thickening agents, coloring agents, optical brightening agents and antifoaming agents.
  • One embodiment of the pre-coating layer comprises carboxymethyl cellulose (CMC), which is a thickening agent.
  • CMC carboxymethyl cellulose
  • a synthetic thickener such as an acrylic copolymer, can also be used.
  • An example of synthetic thickener is Rheocoat 35 from Coatex.
  • the coat weight of the pre-coating layer may for example be 5-12 g/m 2 , such as 6-10 g/m 2 . If the coat weight of the pre-coating is too low, higher amounts of barrier material, which is expensive, are needed in the next coating layer to obtain an effective barrier layer. If the coat weight of the pre-coating is too high, the cost of the product will be unnecessarily high.
  • the barrier coating layer comprises a synthetic rubber, such as styrene-butadiene rubber.
  • the synthetic rubber is normally provided in the form of latex.
  • the barrier coating layer comprises a clay, preferably a platy clay, such as platy kaolin.
  • a platy clay such as platy kaolin.
  • the most preferred type of clay is hyper-platy kaolin.
  • Clay and in particular hyper-platy clay creates a tortous path for moisture transmission and therefore suitable for creating barrier functions.
  • hyper-platy kaolin A specific example of hyper-platy kaolin is the product BarrisurfTM (Imerys).
  • a barrier coating layer consisting of synthetic rubber is sometimes difficult to print.
  • the barrier coating layer thus comprises both the synthetic rubber and the clay.
  • the synthetic rubber and the platy clay may account for at least 50 %, such as at least 75 or 85 %, of the dry weight of the barrier coating layer.
  • the dry weight ratio of clay to synthetic rubber may for example be between 1:1 and 2.4:1, such as between 1.3:1 and 2.1:1.
  • the barrier coating layer may comprise a thickening agent, such as CMC or a synthetic thickener, such as an acrylic copolymer.
  • a thickening agent such as CMC
  • a synthetic thickener such as an acrylic copolymer.
  • Rheocoat 35 from Coatex is an example of a synthetic thickener.
  • the coat weight of the barrier coating layer may for example be 5-15 g/m 2 , such as 6-12 g/m 2 , such as 7-10 g/m 2 . If the coat weight is too low, the barrier coating layer may fail to provide an efficient barrier. If the coat weight is too high, the cost of the product will be unnecessarily high. It is notable that the barrier chemicals are generally relatively expensive.
  • the inside of the sized paper layer is provided with a backside coating.
  • a backside coating A purpose of such a backside coating is to prevent curling that can otherwise occur when paper coated on one side only is dried.
  • the backside coating may comprise a barrier chemical, such as rubber. Again, synthetic rubber, such as styrene-butadiene rubber, is preferred.
  • the backside coating may comprise starch.
  • the coat weight of the backside coating is preferably 1-5 g/m 2 , such as 2-4 g/m 2 .
  • the sized paper layer of the outer paper ply is preferably a Kraft paper, which means that is formed from a pulp prepared according to the Kraft process.
  • the starting material used for preparing the pulp that is used for forming the sized paper layer of the outer paper ply can comprise softwood (which has long fibers and thus forms a strong paper).
  • the sized paper layer is preferably formed from a paper pulp comprising at least 50 % softwood pulp, preferably at least 75 % softwood pulp and more preferably at least 90 % softwood pulp. The percentages are based of the dry weight of the pulp.
  • a sack paper normally has a grammage according to ISO 536 of 50-140 g/m 2 .
  • a sack paper of a higher grammage is stronger, but also more expensive.
  • the grammage is preferably 60-125 g/m 2 and more preferably 65-100 g/m 2 .
  • the grammage according to ISO 536 is preferably 65-150 g/m 2 , such as 75-140 g/m 2 , such as 80-115 g/m 2 .
  • the tensile strength is the maximum force that a paper will withstand before breaking.
  • ISO 1924-3 a stripe having a width of 15 mm and a length of 100 mm is used with a constant rate of elongation.
  • the tensile strength is one parameter in the measurement of the tensile energy absorption (TEA).
  • 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.
  • the filling goods move inside the sack when it hits the floor. This movement means a strain on the sack wall.
  • the TEA should be high, which means that a combination of high tensile strength and good stretch in the paper will then absorb the energy.
  • the stretchability according to ISO 1924-3 of the sized paper layer or the outer paper ply may for example be at least 4.5 % in the machine direction (MD) and at least 5.5 % in the cross direction.
  • the sized paper layer may be creped.
  • the sized paper layer may be creped by a Clupak or Expanda unit.
  • the skilled person knows how to adjust such a unit to obtain a desired stretchability in the MD.
  • the TEA index is the TEA value divided by the grammage.
  • the TEA according to ISO 1924-3 of the outer paper ply may for example be 150-300 J/m 2 in both MD and CD.
  • the TEA index according to ISO 1924-3 of the outer paper ply may for example be 2.2-3.5 J/g in the MD and 2.8-4.2 J/g in the CD.
  • the tear strength according to ISO 1974 of the sized paper layer or the outer paper ply may for example be at least 840 mN, such as at least 950 mN in both the machine direction (MD) and in the cross direction (CD). In one embodiment, the tear strength is at least 860 mN in MD and at least 1000 mN in CD.
  • the sized paper layer may comprise starch.
  • the added amount of starch may be 1-15 kg/ton paper, such as 2-12 kg/ton paper, such as 4-11 kg/ton paper.
  • the starch may for example be a cationic starch or a mixture of cationic and anionic starch.
  • the Gurley porosity according to ISO 5636-5 of the inner paper ply is less than 10 s. Preferably, it is less than 8 s and more preferably less than 6 s.
  • Brown QuickFill Plus and Brown QuickFill SE which are marketed by BillerudKorsnäs and have Gurley porosities of 3 s and 5 s, respectively, are examples of sack papers that can be used for the inner paper ply. Normally, it is pointless to reduce the Gurley value below 2.5 s. Further, it is generally difficult to produce a sack paper of such a low Gurley value and sufficient strength. Ranges for the Gurley porosity of the inner paper ply are thus 2.5-10 s, 2.5-8 s and 2.5-6 s.
  • the inner paper ply is preferably a Kraft paper ply.
  • the starting material used for preparing the pulp that is used for forming the paper of the inner paper ply can comprise softwood.
  • the inner paper ply is preferably formed from a paper pulp comprising at least 50 % softwood pulp, preferably at least 75 % softwood pulp and more preferably at least 90 % softwood pulp. The percentages are based of the dry weight of the pulp.
  • sack paper normally has a grammage according to ISO 536 of 50-140 g/m 2 and a sack paper of a higher grammage is stronger, but also more expensive.
  • the grammage is preferably 55-100 g/m 2 and more preferably 60-90 g/m 2 .
  • the inner paper ply preferably provides substantial dry strength to the sack. Accordingly, the tensile energy absorption (TEA) according to ISO 1924-3 of the inner paper ply is preferably at least 175 J/m 2 in the machine direction (MD). In the cross direction (CD), the TEA according to ISO 1924-3 is preferably at least 182 J/m 2 .
  • the TEA according to ISO 1924-3 is at least 196 J/m 2 in the MD and/or at least 203 J/m 2 in the CD.
  • a typical upper limit for the TEA may be 260 J/m 2 in MD and 270 J/m 2 in CD.
  • the geometric TEA according to ISO 1924-3 of the inner paper ply is preferably at least 178 J/m 2 , such as 178-265 J/m 2 , and more preferably 199-265 J/m 2 .
  • the inner paper ply is advantageously strong already at a relatively low grammage. Therefore, the TEA index according to ISO 1924-3 of the inner paper ply may be at least 2.5 J/g in the MD and at least 2.6 J/g in the CD. Preferably, the TEA index according to ISO 1924-3 of the inner paper ply is at least 2.8 J/g, such as 2.8-3.5 J/g in the MD and at least 2.9 J/g, such as 2.9-3.9 J/g in the CD.
  • the porosity of the inner paper ply of the sack of the present disclosure allows air to pass from the inside of the sack to an interspace between the inner paper ply and the outer paper ply. Further, the sack of the present disclosure is configured to allow air to escape from the interspace between the inner paper ply and the outer paper ply (to the ambient air) during filling of the sack.
  • the sack design is such that air can escape from the interspace between the inner paper ply and the outer paper ply through a top end of the sack during filling of the sack.
  • a top end of the sack may be formed by folding and gluing the plies such that a portion of the top end is not sealed and air can escape from the interspace through the non-sealed portion during filling of the sack.
  • the sack of the present disclosure is preferably a valve sack.
  • Valve sacks are well known to the skilled person.
  • a valve sack is provided with a valve through which it may be filled. Such a valve is normally provided at a folded top end of the sack.
  • a typical valve is further discussed below with reference to figures 1 and 2 .
  • Figure 1 illustrates a multi-ply sack 100 according to an embodiment of the present disclosure having a top end 111 and a bottom end 112.
  • the sack comprises an inner paper ply 101 and an outer paper ply 102.
  • the paper layer of the outer paper ply 102 is sized with at least one hydrophobic size. Further, the paper layer is coated with a pre-coating and a barrier coating. To facilitate deaeration, the Gurley porosity according to ISO 5636-5 of the inner paper ply 101 is less than 10 s.
  • the sack 100 is configured to allow air to escape (the air escape is illustrated by the arrow 103) from an interspace between the inner paper ply 101 and the outer paper ply 102 through the top end 111 of the sack 100 during filling of the sack 100.
  • air escape is illustrated by the arrow 103
  • Such a deaeration is achieved by a non-sealed portion 104 forming an opening between the inner paper ply 101 and the outer paper ply 102 at the top end 111.
  • the non-sealed portion 104 may be flanked by sealed portions 105, i.e. portions in which the outer paper ply 102 is sealed (preferably glued) to the inner paper ply 101.
  • the width of the non-sealed portion may for example be 150-160 mm and for a 35 kg having a width of 440-460 mm, the width of the non-sealed portion may be 190-200 mm.
  • the top end 111 of the sack 100 of figure 1 further has a filling valve 106 into which a filling spout may be inserted.
  • the arrow 107 illustrates how the filling spout is inserted into the valve 106.
  • a ceiling of the valve 106 is reinforced by a valve reinforcement 108, which preferably is composed of paper. Because of the reinforcement provided by the valve reinforcement 108, the sack 100 can hang on the filling spout during filling without breaking. When fully opened, the opening of the valve 106 may be approximatively diamond-shaped.
  • Figure 2 illustrates the sack 100 of figure 1 onto which a top patch 201 has been applied.
  • the top patch reinforces top end 111 of the sack 100.
  • a slit 202 in the top patch 201 ensures that the air still can escape through the non-sealed portion 104 during filling.
  • the slit 202 is thus substantially aligned with the non-sealed portion 104.
  • the width of the slit 202 is preferably approximately the same as the width of the non-sealed portion 104.
  • the sack 100 is oriented such that the opening formed by the non-sealed portion 104 is facing down.
  • the dimensions of the sack of the present disclosure may for example be such that it has a volume of 8-45 liters, preferably 12-45 liters in a filled configuration.
  • 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 17-60 kg.
  • 25 kg sacks, 35 kg sacks and 50 kg sacks are demanded on the market and may thus 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.
  • a coated paper for use in a sack, wherein the coated paper comprises a paper layer sized with at least one hydrophobic size; the sized paper layer is creped; the sized paper layer is provided on a first side with a pre-coating layer and a barrier coating layer; the pre-coating layer comprises binder and inorganic filler in a dry weight ratio of between 10:100 and 50:100; the sized paper is provided on a second side with a backside coating layer, the grammage according to ISO 536 of said coated paper is 75-140 g/m 2 , such as 80-115 g/m 2 .
  • the second aspect is a preferred embodiment of the outer paper ply of the first aspect.
  • the embodiments of the outer paper ply of the first aspect discussed above apply mutatis mutandis to the coated paper of the second aspect.
  • Bleached kraft papers having a grammage of 70 or 80 g/m 2 for use as a sized paper layer according to the present disclosure were prepared as follows.
  • a wet strength agent was added. This is however not necessary when preparing a sized paper layer according to the present disclosure because the sized paper layer is coated to prevent soaking.
  • Bleached kraft paper having a grammage of 80 g/m 2 for use as a sized paper layer according to the present disclosure is prepared as follows.
  • an aqueous pre-coating composition comprising styrene-butadiene latex and CaCO 3 pigment in a dry weight ratio of 30:100 is prepared.
  • CMC thickening agent
  • the pH of the pre-coating composition is adjusted to 8.3 using NaOH.
  • the pre-coating composition is then applied to sized paper prepared according to trial 2 above using a blade coater.
  • the pressure and angle of the coating blade is adjusted such that the coat weight of the pre-coating is 8 g/m 2 .
  • an aqueous backside coating composition comprising starch (4-6 %) and styrene-butadiene latex (2-5 %) is prepared.
  • the backside coating composition is applied to the backside of the paper via a roll distributing system at the same position as the coater or the pre-coating, i.e. opposite of the blade, to obtain a backside coat weight of 2-4 g/m 2 .
  • the pre-coating is dried with IR-heaters and drying cylinders to such an extent that the barrier coating composition (described below) can be applied without problems like scuffing of the pre-coating.
  • An aqueous barrier coating composition comprising styrene-butadiene latex and hyper-platy kaolin pigment (BarrisurfTM (Imerys)) in a dry weight ratio of 50:100 is prepared.
  • An acrylic co-polymer (Rheocoat 35 from Coatex) is added as a thickening agent to obtain a viscosity of about 1200 cP (measured according to Scan-P 50:84, but with a sample temperature of 34-40 °C). Further, the pH of the barrier coating composition is adjusted to about 8 using NaOH.
  • the barrier coating composition is applied with a roll which is dipped in a chest with the barrier coating composition and the excess is removed with a coating blade.
  • the pressure and angle of the coating blade is adjusted such that the coat weight of the barrier coating is 8 g/m 2 .
  • the barrier coating surface is dried with IR-dryers, which allowing a fast setting of the coating colour. The drying continues with cylinders and hot air until the desired moisture level is obtained. Normally the finished product has a dry content of 92-95%.
  • the coated paper is the calendared in order to compress the coating and the fibers to make the surface and the fiber network even more closed and therefore more resistant to penetration of water. For the same reason rain will easier leave the surface of the sack.
  • Sacks (Sack 1 and Sack 2) are then prepared using the coated sack paper prepared according to the above as the outer paper ply and a commercial sack paper as the inner paper ply.
  • Outer paper ply Coated sack paper prepared according to the above Inner paper ply: QuickFill® Brown SE (unbleached), marketed by BillerudKorsnäs AB (Sweden), see table 2
  • the sacks are conditioned according to ISO 6599-1.
  • the dimensions of each sack are 400 mm x 450 mm x 110 mm.
  • the result of the drop test is expected to be comparable to or better than the result obtained with a comparable "normal" sack with a slitted or perforated free film.
  • Sacks according to Sack 1 or Sack 2 are filled with about 25 kg of cement.
  • the filled sacks are exposed to rain conditions according to ISO 2875 for 2, 4, 6 or 8 hours. During the exposures, the sacks are oriented with the deaeration opening facing down.
  • the sacks are cut open and the cement is visually inspected.
  • the condition of the cement is expected to be acceptable, also after 8 hours of exposure.
  • Sacks from the rain rest exposed to 2 hours of rain conditions are expected to survive several drops from a height of 80 cm without breaking.
  • Sacks from the rain rest exposed to 8 hours of rain conditions are expected to survive several drops from a height of 40 cm without breaking.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Storage Of Web-Like Or Filamentary Materials (AREA)
  • Packages (AREA)
  • Devices For Checking Fares Or Tickets At Control Points (AREA)
EP15201668.9A 2015-12-21 2015-12-21 Regendichter papiersack Withdrawn EP3184694A1 (de)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP15201668.9A EP3184694A1 (de) 2015-12-21 2015-12-21 Regendichter papiersack
FIEP16825737.6T FI3394342T3 (fi) 2015-12-21 2016-12-21 Vedenpitävä paperisäkki
EP16825737.6A EP3394342B1 (de) 2015-12-21 2016-12-21 Regendichter papiersack
PCT/EP2016/082115 WO2017108910A1 (en) 2015-12-21 2016-12-21 Rainproof paper sack

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP15201668.9A EP3184694A1 (de) 2015-12-21 2015-12-21 Regendichter papiersack

Publications (1)

Publication Number Publication Date
EP3184694A1 true EP3184694A1 (de) 2017-06-28

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EP15201668.9A Withdrawn EP3184694A1 (de) 2015-12-21 2015-12-21 Regendichter papiersack
EP16825737.6A Active EP3394342B1 (de) 2015-12-21 2016-12-21 Regendichter papiersack

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP16825737.6A Active EP3394342B1 (de) 2015-12-21 2016-12-21 Regendichter papiersack

Country Status (3)

Country Link
EP (2) EP3184694A1 (de)
FI (1) FI3394342T3 (de)
WO (1) WO2017108910A1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7268614B2 (ja) * 2020-01-27 2023-05-08 王子ホールディングス株式会社 バリア性積層体
FR3113070A1 (fr) * 2020-07-30 2022-02-04 Vicat Papier et sac d’emballage, déperlants, destinés au conditionnement de produits divers
FI4198199T3 (fi) * 2021-12-14 2024-04-17 Billerud Ab Publ Säkissä käytettäväksi soveltuva päällystetty paperi
CN117364529A (zh) * 2023-10-30 2024-01-09 山东世纪阳光纸业集团有限公司 一种阻湿涂布纸用预涂布液、制备方法及其应用

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0718437A1 (de) * 1994-12-20 1996-06-26 International Paper Company Recyclingfähiger und repulpierbarer Rieseinschlag und zugehörige Verfahren zur Herstellung
WO1998057861A1 (en) * 1997-06-18 1998-12-23 Bpb Plc Paper sack
WO1999002772A1 (en) 1997-07-09 1999-01-21 Assidomän AB Kraft paper and method for making the same
WO2003010055A1 (en) * 2001-07-23 2003-02-06 Shinduck Ind. Co.,Ltd Paper sack
US20030226648A1 (en) * 2002-06-06 2003-12-11 Mcdonnell William T. Multiple ply paperboard material having improved oil and grease resistance and stain masking properties and method for forming same
DE602005003089T2 (de) * 2004-10-20 2008-08-21 Smurfit Lembacel Verbesserungen an mehrschichtige Papiersäcke mit einem luftdichten Film oder ähnliches der zwischen zwei Papierschichten angeordnet ist
WO2011000942A1 (en) * 2009-07-03 2011-01-06 Billerud Ab Sack paper with vapour barrier
WO2013069788A1 (ja) * 2011-11-10 2013-05-16 日本製紙株式会社 紙製バリア包装材料
WO2013164646A1 (en) * 2012-05-04 2013-11-07 Imerys Minerals Limited Fibre based material

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0718437A1 (de) * 1994-12-20 1996-06-26 International Paper Company Recyclingfähiger und repulpierbarer Rieseinschlag und zugehörige Verfahren zur Herstellung
WO1998057861A1 (en) * 1997-06-18 1998-12-23 Bpb Plc Paper sack
WO1999002772A1 (en) 1997-07-09 1999-01-21 Assidomän AB Kraft paper and method for making the same
WO2003010055A1 (en) * 2001-07-23 2003-02-06 Shinduck Ind. Co.,Ltd Paper sack
US20030226648A1 (en) * 2002-06-06 2003-12-11 Mcdonnell William T. Multiple ply paperboard material having improved oil and grease resistance and stain masking properties and method for forming same
DE602005003089T2 (de) * 2004-10-20 2008-08-21 Smurfit Lembacel Verbesserungen an mehrschichtige Papiersäcke mit einem luftdichten Film oder ähnliches der zwischen zwei Papierschichten angeordnet ist
WO2011000942A1 (en) * 2009-07-03 2011-01-06 Billerud Ab Sack paper with vapour barrier
WO2013069788A1 (ja) * 2011-11-10 2013-05-16 日本製紙株式会社 紙製バリア包装材料
WO2013164646A1 (en) * 2012-05-04 2013-11-07 Imerys Minerals Limited Fibre based material

Also Published As

Publication number Publication date
EP3394342A1 (de) 2018-10-31
WO2017108910A1 (en) 2017-06-29
FI3394342T3 (fi) 2024-05-14
EP3394342B1 (de) 2024-02-14

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