Gas barrier laminate and packaging bag

Abstract

Provided are: a gas barrier laminate which has excellent gas barrier properties and can be used even in applications involving contact with water; and a packaging bag obtained by using the gas barrier laminate. This gas barrier laminate has a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, wherein the gas barrier layer contains a gas barrier resin, has an oxygen permeability of at most 5 mL / (m2∙day∙atm) at 23ºC and 50% RH, and has an edge wick value of at most 1 g / 1,000 mm2 with respect to water at 23ºC in a contact time of one hour. This packaging bag is obtained by using the gas barrier laminate.

Description

Gas barrier laminate and packaging bag

[0001] The present invention relates to a gas barrier laminate and a packaging bag.

[0002] BACKGROUND ART Conventionally, gas barrier laminates have been known which are configured by providing a gas barrier layer on a paper substrate in order to impart gas barrier properties to the paper substrate.

[0003] Japanese Patent Application Laid-Open No. 2023-006393 describes a method for producing a gas barrier paper packaging material, which includes at least a barrier layer forming step of applying a barrier coating agent to one side of a sealant film to form a barrier layer, and a lamination step of laminating the barrier layer and a paper base layer via an adhesive layer.

[0004] However, the gas barrier paper packaging material described in JP 2023-006393 A has poor water resistance, and has the problem that its use is limited in situations where it comes into contact with water.

[0005] The present invention has been made in view of the existence of the above-mentioned problems, and aims to provide a gas barrier laminate that has excellent gas barrier properties and can be used even in situations where it comes into contact with water, and a packaging bag made using the gas barrier laminate.

[0006] The present inventors have found that in a gas barrier laminate having a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, by setting the oxygen permeability and Edgewick value to specific values ​​or less, the gas barrier laminate has excellent gas barrier properties and can also be used in applications involving contact with water. That is, the present invention has the following configuration. <1> A gas barrier laminate having a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, the gas barrier layer contains a gas barrier resin, and the oxygen permeability at 23°C and 50% RH is 5 mL / (m ２ · day · atm) or less, and the Edgewick value in water at 23 ° C. after a contact time of 1 hour is 1 g / 1000 mm ２A gas barrier laminate as set forth below. <2> The gas barrier laminate according to <1>, which has a resin layer on a surface of a paper substrate opposite to the surface on which the sealant layer, gas barrier layer, and adhesive layer are formed. <3> The gas barrier laminate according to <1> or <2>, in which the paper substrate is provided with a water repellent. <4> The gas barrier laminate according to any one of <1> to <3>, in which the paper substrate contains paraffin wax. <5> The gas barrier laminate according to any one of <1> to <4>, in which the gas barrier resin contains at least one resin selected from the group consisting of an ethylene-vinyl alcohol copolymer and a polyurethane resin. <6> The gas barrier laminate according to any one of <1> to <5>, in which the content of the gas barrier resin (preferably an ethylene-vinyl alcohol copolymer) in the gas barrier layer is 70% by mass or more. <7> The gas barrier laminate according to any one of <1> to <6>, in which the gas barrier layer further contains an adhesion promoter. <8> The gas barrier laminate according to <7>, wherein the adhesion promoter contains a polyethyleneimine resin. <9> The gas barrier laminate according to <7> or <8>, wherein the content of the adhesion promoter (preferably a polyethyleneimine resin) in the gas barrier layer is 0.5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the gas barrier resin (preferably an ethylene-vinyl alcohol copolymer). <10> The gas barrier laminate according to any one of <7> to <9>, wherein the content of the adhesion promoter (preferably a polyethyleneimine resin) in the gas barrier layer is 0.5% by mass or more and 15% by mass or less. <11> The gas barrier laminate according to any one of <7> to <9>, wherein the coating weight of the gas barrier layer is 0.5 g / m ２ 3g / m or more ２ <12> The gas barrier laminate according to any one of <1> to <10>, wherein the basis weight of the paper substrate is 20 g / m or less. ２ More than 200g / m ２ The gas barrier laminate according to any one of <1> to <11>, wherein the gas barrier laminate has a paper base material content of 50% by mass or more. <13> The gas barrier laminate according to any one of <1> to <12>, wherein the gas barrier laminate has a paper base material content of 50% by mass or more. <14> A packaging bag made using the gas barrier laminate according to any one of <1> to <13>.

[0007] Hereinafter, embodiments of the present invention will be described in detail. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "X to Y" means a numerical range including X as the lower limit and Y as the upper limit. When a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, "(meth)acrylic" is a generic term that includes both acrylic and methacrylic. Furthermore, in this specification, unless otherwise specified, operations and measurements of physical properties, etc. are performed at room temperature (20-25°C) and a relative humidity of 40-50%.

[0008] [Gas barrier laminate] The gas barrier laminate of this embodiment (hereinafter also simply referred to as "gas barrier laminate") has a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, and the gas barrier layer contains a gas barrier resin, and has an oxygen permeability of 5 mL / (m ２ · day · atm) or less, and the Edgewick value in water at 23 ° C. after a contact time of 1 hour is 1 g / 1000 mm ２ The gas barrier laminate of this embodiment provides a packaging bag that has excellent gas barrier properties and can be used in situations where it comes into contact with water.

[0009] <Sealant Layer> The sealant layer is a layer that melts and adheres when heated, ultrasonically, or the like. The gas barrier laminate of this embodiment may have sealant layers on both sides of the paper substrate. Furthermore, the gas barrier laminate of this embodiment may have two or more sealant layers formed on one side of the paper substrate. In a packaging bag made using the laminate of this embodiment, it is preferable that at least the surface that comes into contact with the contents is a sealant layer.

[0010] Examples of resins constituting the sealant layer include polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; ethylene-acrylic resins such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-methyl(meth)acrylate copolymer; styrene-acrylic resins such as styrene-(meth)acrylic acid copolymer; and modified products thereof. These resins may be used alone or in combination of two or more. Among these, from the viewpoints of heat sealability and gas barrier properties, the resin constituting the sealant layer preferably contains a polyolefin-based resin, and more preferably contains polyethylene. The polyethylene may be low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), or high-density polyethylene (HDPE). Among these, LLDPE is preferred, particularly for small bag applications, where high-speed bag production is required and high adhesiveness is required.

[0011] The sealant layer can be formed, for example, by preparing a coating liquid for the sealant layer, applying the coating liquid to a substrate or the like, and drying the coating liquid, or by using a resin film for the sealant layer. However, it is preferable to use a resin film for the sealant layer. When the sealant layer is laminated as a resin film for the sealant layer, the resin film may be unstretched or may be uniaxially or biaxially stretched. Furthermore, the resin film for the sealant layer may be a laminate film in which two or more resins are laminated.

[0012] The thickness of the sealant layer is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more, even more preferably 15 μm or more, and more preferably 70 μm or less, even more preferably 40 μm or less. From the viewpoint of sufficient heat-sealing properties, the thickness of the sealant layer is preferably equal to or more than the above-mentioned lower limit, and from the viewpoint of reducing the environmental load, the thickness is preferably equal to or less than the above-mentioned upper limit.

[0013] <Gas Barrier Layer> The gas barrier layer is a layer that primarily has the function of suppressing oxygen gas permeation (gas barrier properties) and contains a gas barrier resin. The gas barrier layer may be formed by applying a coating liquid containing a gas barrier resin, or by laminating a gas barrier resin using melt extrusion, an adhesive, or the like, or by forming a vapor-deposited layer selected from the group consisting of a metal vapor-deposited layer and an inorganic vapor-deposited layer, or by laminating a resin film having a vapor-deposited layer selected from the group consisting of a metal vapor-deposited layer and an inorganic vapor-deposited layer. Among these, the gas barrier layer is preferably formed by applying a coating liquid for the gas barrier layer containing a gas barrier resin, and more preferably by applying the coating liquid for the gas barrier layer to a resin film for the sealant layer.

[0014] (Gas barrier resin) In this specification, the term "gas barrier resin" refers to a resin having an oxygen permeability of 50 mL / (m) at 23°C and 50% RH, measured in accordance with JIS K 7126-2:2006, when a 10 μm thick film is formed on a 30 μm thick low-density polyethylene film. ２ ·day·atm) or less. Examples of gas barrier resins include polyvinyl alcohol, polyvinyl alcohol-based resins such as ethylene-vinyl alcohol copolymers, vinylidene chloride-based resins such as polyvinylidene chloride, polyurethane-based resins, and the like. Among these, from the viewpoints of environmental load and gas barrier properties, the gas barrier resin preferably contains one or more selected from the group consisting of polyvinyl alcohol-based resins and polyurethane-based resins, more preferably contains one or more selected from the group consisting of ethylene-vinyl alcohol copolymers and polyurethane-based resins, and even more preferably contains an ethylene-vinyl alcohol copolymer.

[0015]

[0044] From the viewpoint of improving gas barrier properties, the content of the gas barrier resin (preferably one or more selected from the group consisting of polyvinyl alcohol resins and polyurethane resins, more preferably an ethylene-vinyl alcohol copolymer) in the gas barrier layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more, of the solid content of the gas barrier layer, and the upper limit is 100% by mass.

[0016] Commercially available polyvinyl alcohol resins may be used, such as "Exceval (trade name)" manufactured by Kuraray Co., Ltd. and "Ebersolve (trade name)" manufactured by Nippon Cima Co., Ltd.

[0017] The polyurethane-based resin is preferably one that can be prepared into one or more selected from the group consisting of polyurethane-based resin dispersions and emulsions, more preferably one that can be prepared into a polyurethane-based resin dispersion or emulsion, and even more preferably one that can be prepared into a polyurethane-based resin emulsion.

[0018] The polyurethane resin may have a hydroxy group, and the hydroxy value thereof is preferably 50 mgKOH / g or more and 1000 mgKOH / g or less, more preferably 100 mgKOH / g or more, and even more preferably 150 mgKOH / g or more. The upper limit of the hydroxy value is not particularly limited, but is more preferably 800 mgKOH / g or less, and even more preferably 600 mgKOH / g or less. When the hydroxy value of the polyurethane resin is within the above range, the gas barrier layer is more likely to exhibit gas barrier properties.

[0019] As the polyurethane-based resin, commercially available products may be used, and examples thereof include "HPU-W013A (trade name)" (hydroxyl value: 235 mg KOH / g, acid value: 30 mg KOH / g) manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., and "Takelac W series (trade name)," "Takelac WPB series (trade name)," and "Takelac WS series (trade name)" manufactured by Mitsui Chemicals, Inc.

[0020] (Adhesion Imparting Agent) Depending on the type of gas barrier resin, the adhesion between the gas barrier layer and the adhesive layer may be poor, and this is particularly noticeable when an ethylene-vinyl alcohol copolymer is used. Therefore, it is preferable to use an adhesion imparting agent in the gas barrier layer in addition to the gas barrier resin. The adhesion imparting agent preferably contains a polyethyleneimine resin. Therefore, in the gas barrier laminate of this embodiment, the gas barrier layer preferably contains an ethylene-vinyl alcohol copolymer and a polyethyleneimine resin. The gas barrier laminate of this embodiment has excellent gas barrier properties and good adhesion between the gas barrier layer and the adhesive layer, and therefore excellent heat sealability. A commercially available polyethyleneimine resin may be used, and an example thereof is "Epomin (trade name)" manufactured by Nippon Shokubai Co., Ltd.

[0021] When the gas barrier layer contains an adhesion promoter, the content of the adhesion promoter (preferably a polyethyleneimine resin) is preferably 0.5 parts by mass or more and 15 parts by mass or less, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the gas barrier resin (preferably an ethylene-vinyl alcohol copolymer). From the viewpoints of adhesiveness and heat sealability, the content of the adhesion promoter is preferably at least the above-mentioned lower limit, and from the viewpoint of gas barrier properties, it is preferably at most the above-mentioned upper limit.

[0022]

[0044] When the gas barrier layer contains an adhesion promoter, the content of the adhesion promoter (preferably a polyethyleneimine resin) in the gas barrier layer is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more, even more preferably 3% by mass or more, and more preferably 10% by mass or less, and even more preferably 7% by mass or less. From the viewpoints of adhesiveness and heat sealability, the content of the adhesion promoter in the gas barrier layer is preferably at least the above-mentioned lower limit, and from the viewpoint of gas barrier properties, it is preferably at most the following upper limit.

[0023]

[0047] From the viewpoints of gas barrier property, adhesiveness and heat sealability, the total content of the gas barrier resin (preferably an ethylene-vinyl alcohol copolymer) and adhesion promoter (preferably a polyethyleneimine resin) in the gas barrier layer is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more (upper limit: 100% by mass).

[0024] From the viewpoint of improving gas barrier properties, the gas barrier layer may further contain a layered inorganic compound in addition to the gas barrier resin and, if necessary, an adhesion promoter. By using a layered inorganic compound in the gas barrier layer, the layered inorganic compound is easily laminated approximately parallel to the plane (surface) of the paper substrate. This reduces the area in the planar direction where the layered inorganic compound is not present, making it easier to suppress oxygen permeation. Furthermore, since the layered inorganic compound is arranged parallel to the plane of the paper substrate in the thickness direction, oxygen in the layer permeates while bypassing the layered inorganic compound, resulting in a maze effect that suppresses oxygen permeation. As a result, the gas barrier layer is more likely to exhibit excellent oxygen barrier properties. When a layered inorganic compound is incorporated into the gas barrier layer, the content of the layered inorganic compound is not particularly limited, but is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the gas barrier resin (preferably a polyurethane-based resin) in the gas barrier layer. Examples of layered inorganic compounds include mica, kaolin, pyrophyllite, talc, bentonite, montmorillonite, vermiculite, chlorite, septite chlorite, serpentine, and stilpnomelane. Among these, one or more selected from the group consisting of mica, bentonite, kaolin, and talc are preferred, and one or more selected from the group consisting of mica and kaolin are more preferred. Examples of mica include synthetic mica, white mica (muscovite), sericite (sericite), phloxopite, biotite (biotite), fluorphlogopite (artificial mica), red mica, soda mica, vanadium mica, illite, zinc mica, paragonite, and brittle mica, with synthetic mica being preferred.

[0025] When the gas barrier layer contains a layered inorganic compound, it preferably contains a cationic resin in order to suppress aggregation of the layered inorganic compound and improve the gas barrier properties.

[0026] (Cationic Resin) Examples of cationic resins include polyamine resins, cation-modified polyamide resins (for example, amine-modified polyamide resins), polyamide epichlorohydrin resins, polyalkylene polyamine resins, polyamide compounds, polyamidoamine-epihalohydrin or formaldehyde condensation reaction products, polyamine-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamidoamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea compounds, polyamine polyurea compounds, polyamidoamine polyurea compounds and polyamidoamine compounds, polyvinylpyridine, amino-modified acrylamide compounds, polyvinylamine resins, and polydiallyldimethylammonium chloride. Among these, the cationic resin is preferably at least one selected from the group consisting of polyamine resins, cation-modified polyamide resins, and polyamide-epichlorohydrin resins, and more preferably a cation-modified polyamide resin.

[0027] As the cationic resin, commercially available products may be used, and examples thereof include "Sumirez Resin SPI-203(50)H (trade name)," "Sumirez Resin SPI-102A (trade name)," and "Sumirez Resin SPT-106N (trade name)," manufactured by Taoka Chemical Co., Ltd.

[0028] When the gas barrier layer contains a layered inorganic compound and a cationic resin, the content of the cationic resin is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, and more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the layered inorganic compound.

[0029] The coating amount (solid content) of the gas barrier layer is preferably 0.5 g / m ２ 5g / m or more ２More preferably, it is 0.7 g / m or less. ２ More preferably, it is 3 g / m or more. ２ The coating amount (solid content) of the gas barrier layer is preferably at least the above lower limit from the viewpoint of improving gas barrier properties, and is preferably at most the above upper limit from the viewpoint of obtaining a gas barrier laminate with excellent recyclability.

[0030] In addition to the above components, the gas barrier layer may contain, as needed, appropriate additives such as resins other than the above components (for example, ethylene-acrylic copolymers such as ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers), pigments, dispersants, surfactants, defoamers, wetting agents, dyes, color adjusters, and thickeners, within the limits that do not impair the effects of the layer.

[0031] <Adhesive Layer> The adhesive layer functions to bond the gas barrier layer and the paper substrate. The adhesive layer is not particularly limited and may be any of solventless, organic solvent, and aqueous types. However, from the viewpoint of ensuring the shape stability of the paper substrate, it is preferable to use an organic solvent-based adhesive or a solventless adhesive. Examples of components constituting the adhesive layer include (meth)acrylic acid ester copolymers, α-olefin copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol-based resins, polyurethane-based resins, styrene-butadiene copolymers, polyvinyl chloride resins, epoxy resins, melamine resins, silicone resins, natural rubber, casein, and starch. Among these, from the viewpoints of easy availability and obtaining good adhesion, it is preferable to include one or more selected from the group consisting of (meth)acrylic acid ester copolymers, ethylene-vinyl acetate copolymers, and polyurethane-based resins, and it is more preferable to include a polyurethane-based resin.

[0032] For the adhesive layer, a commercially available adhesive may be used as appropriate, and examples thereof include a combination of "Nippolan ID-816 (trade name)" (manufactured by Tosoh Corporation) and "HARDENER 300 (trade name)" (manufactured by Tosoh Corporation), and a combination of "Dickdry LX-500 (trade name)" (manufactured by DIC Corporation) and "Dickdry KW-75 (trade name)" (manufactured by DIC Corporation).

[0033] The adhesive layer can be formed by applying an adhesive containing the above-mentioned components and drying it. The coating amount (solid content) of the adhesive layer is preferably 1 g / m ２ 10g / m or more ２ More preferably, it is 2 g / m or less. ２ More preferably, 3 g / m ２ More preferably, it is 7 g / m or more. ２ More preferably, 5 g / m or less ２ The coating amount (solid content) of the adhesive layer is preferably at least the above lower limit from the viewpoint of improving the adhesion between the sealant layer or gas barrier layer and the paper substrate, and is preferably at most the above upper limit from the viewpoint of cost and economy.

[0034] <Paper base material> Examples of raw pulp constituting the paper base material include wood pulp, non-wood pulp, and deinked pulp. Wood pulp is not particularly limited, but examples include hardwood kraft pulp (LKP) such as bleached hardwood kraft pulp (LBKP) and unbleached hardwood kraft pulp (LUKP), softwood kraft pulp (NKP) such as bleached softwood kraft pulp (NBKP) and unbleached softwood kraft pulp (NUKP), chemical pulp such as sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), and oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemi-groundwood pulp (CGP), groundwood pulp (GP), and mechanical pulp such as thermomechanical pulp (TMP) and chemi-thermomechanical pulp (CTMP). Non-wood pulps include, but are not limited to, cotton-based pulps such as cotton linters and cotton lint, and non-wood pulps such as hemp, straw, bamboo, and bagasse. Deinked pulps include, but are not limited to, deinked pulp made from recycled paper. The raw pulp may be one of the above types alone or a combination of two or more types. The raw pulp may also be mixed with organic synthetic fibers such as polyamide fibers and polyester fibers, recycled fibers such as polynosic fibers, and inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers. From the standpoints of availability and recyclability, the raw pulp preferably includes one or more types selected from the group consisting of wood pulps, more preferably one or more types selected from the group consisting of hardwood kraft pulps and softwood kraft pulps, and even more preferably one or more types selected from the group consisting of hardwood kraft pulps.

[0035] Known internal additives may be added to the paper substrate as needed. Examples of internal additives include fillers, sizing agents, dry strength agents, wet strength agents, retention aids (e.g., aluminum sulfate), pH adjusters, drainage aids, water-resistant agents, softeners, antistatic agents, antifoaming agents, slime control agents, dyes, and pigments. Examples of fillers include mineral pigments such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, and smectite, as well as organic pigments such as polystyrene resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin, and hollow microparticles thereof. Examples of sizing agents include rosin-based, alkyl ketene dimer-based, alkenyl succinic anhydride-based, styrene-acrylic, higher fatty acid-based, and petroleum resin-based sizing agents. Dry strength agents (paper strength agents) include cationic starch, unmodified, cationic or amphoteric polyacrylamide polymers, carboxymethyl cellulose, etc. Wet strength agents include polyamide polyamine epichlorohydrin resin (PAE), melamine-formaldehyde resin, urea-formaldehyde resin, etc.

[0036] In the papermaking of paper substrates, a known wet papermaking machine (for example, a Fourdrinier papermaking machine, a gap former papermaking machine, a cylinder papermaking machine, a short wire papermaking machine, etc.) can be appropriately selected and used. The paper layer formed by the papermaking machine is preferably transported, for example, on a felt and dried in a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying in the dryer.

[0037] From the viewpoint of obtaining a gas barrier laminate having a desired Edgewick value, it is preferable that the paper substrate be provided with a water repellent. That is, it is preferable that the paper substrate contains a water repellent. Examples of water repellents include various waxes, higher fatty acid derivatives, chromates, zirconium salts, polyolefin resins, synthetic resins, silicone resins, and fluorine compounds. Also usable as water repellents are rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, styrene sizing agents, neutral rosin sizing agents, alkenyl succinic anhydride, and alkyl ketene dimers, which are commonly used as internal sizing agents. Specific examples of water repellents include plant-based waxes such as carnauba wax, cotton wax, Japan wax, and rice wax; animal-based waxes such as beeswax and lanolin; mineral waxes such as montan wax, ozokerite, ceresin, and wax extracted from oil shells; and petroleum-based waxes such as paraffin, microcrystalline wax, and petrolatum. These may be used alone or in combination. Among these, from the above viewpoint, it is preferable that the paper substrate contains paraffin wax, that is, it is more preferable that the paper substrate contains paraffin wax.

[0038] The surface treatment liquid containing a water-repellent preferably contains a water-soluble binder from the viewpoint of improving the surface strength of the paper substrate and suppressing the generation of paper dust. The water-soluble binder is solid or pasty at 25°C and has a solubility in water at 20°C of 10 g / 100 g or more. Solubility can be determined visually. Examples of water-soluble binders include various starches such as oxidized starch, esterified starch, and cold-water-soluble starch; proteins such as casein, soy protein, and synthetic protein; cellulose derivatives such as carboxymethyl cellulose and methyl cellulose; polyvinyl alcohol resins and modified products thereof; and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of effectively improving the surface strength of the paper substrate, it is preferable that the water-soluble binder contains one or more selected from the group consisting of polyvinyl alcohol resins and modified products thereof.

[0039] When a water-soluble binder is blended in the surface treatment liquid, the blending amount of the water-soluble binder is preferably 10 parts by mass or more and 70 parts by mass or less, more preferably 15 parts by mass or more, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the water repellent. The blending amount of the water-soluble binder is preferably equal to or more than the above-mentioned lower limit from the viewpoint of improving the surface strength of the paper substrate, and is preferably equal to or less than the above-mentioned upper limit from the viewpoint of suppressing a decrease in water repellency.

[0040] In order to improve the surface strength of the paper substrate, the surface treatment liquid may contain, in addition to a water-soluble binder, a binder such as a conjugated diene copolymer latex such as a styrene-butadiene copolymer or a methyl methacrylate-butadiene copolymer, an acrylic (co)polymer latex, or a vinyl (co)polymer latex such as an ethylene-vinyl acetate copolymer. The binder refers to one having a solubility of less than 10 g / 100 g in water at 20°C.

[0041] When a binder is blended in the surface treatment liquid, the blending amount of the binder is preferably 40 parts by mass or more and 90 parts by mass or less, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and more preferably 80 parts by mass or less, relative to 100 parts by mass of the water repellent.

[0042] In addition to the water-soluble binder and the binder, the surface treatment liquid may appropriately contain an anti-slip agent, a pigment, a thickener, a water retention agent, an antioxidant, an anti-aging agent, a conductivity inducer, an antifoaming agent, an ultraviolet absorber, a dispersant, a pH adjuster, a release agent, a water-resistant agent, and the like, as needed.

[0043] The coating amount (solid content) of the surface treatment liquid per one side is preferably 0.5 g / m ２ 4.0g / m or more ２ More preferably, it is 1.0 g / m or less. ２ More preferably, it is 3.0 g / m or more. ２The coating amount (solid content) of the surface treatment liquid per side is preferably at least the above lower limit from the viewpoint of improving the surface strength of the paper substrate and improving water repellency, and is preferably at most the above upper limit from the viewpoint of handleability when producing the gas barrier laminate.

[0044] The paper substrate is preferably formed by applying or impregnating the surface treatment liquid and drying. The method of impregnating the surface treatment liquid allows the water repellent to sufficiently penetrate into the interior of the paper substrate, making it possible to adjust the edge wick to a desired range. Furthermore, the method of applying the surface treatment liquid also allows the water repellent to penetrate not only the surface of the paper substrate but also into the interior of the paper substrate, making it possible to adjust the edge wick to a desired range. Examples of application methods include methods using a roll coater such as a gate roll coater, an air knife coater, a bar coater, a blade coater, a spray coater, a curtain coater, a die coater, or the like.

[0045] The paper substrate obtained as described above may be subjected to a surface treatment using a calendar to make the thickness and profile uniform. For the calendar treatment, a known calendaring machine can be appropriately selected and used.

[0046] The basis weight of the paper substrate is preferably 20 g / m ２ More than 300g / m ２ More preferably, it is 30 g / m or less. ２ More preferably, 40 g / m ２ More preferably, it is 200 g / m or more. ２ More preferably 150 g / m or less ２ More preferably, 100 g / m or less ２ From the viewpoint of recyclability, the basis weight of the paper substrate is preferably at least the above lower limit, and from the viewpoint of formability of a packaging bag made using the gas barrier laminate, it is preferably at most the above upper limit. In particular, when the packaging bag is a small bag, from the viewpoint of bag-making processability and openability, the basis weight of the paper substrate is more preferably 70 g / m ２ The basis weight of the paper substrate is measured in accordance with JIS P 8124:2011.

[0047] From the viewpoint of recyclability, the content of the paper substrate in the gas barrier laminate is preferably 50% by mass or more, more preferably 55% by mass or more, and although there is no particular upper limit, it is preferably 95% by mass or less.

[0048] <Resin Layer> From the viewpoints of protecting the paper substrate, improving the water resistance of the gas barrier laminate, preventing exposure of the paper substrate components, and complying with food regulations, the gas barrier laminate of this embodiment preferably has a resin layer on the side of the paper substrate opposite the side having the sealant layer, gas barrier layer, and adhesive layer. That is, the gas barrier laminate preferably has, for example, a sealant layer, a gas barrier layer, an adhesive layer, a paper substrate, and a resin layer in this order. In a packaging bag made using this laminate, the sealant layer side comes into contact with the contents, and the resin layer side becomes the printed side. From the viewpoint of complying with food regulations, it is preferable that the printed components are not exposed, so it is preferable to print on the inside of the resin layer (the side laminated with the paper substrate) and then laminate it with the paper substrate. Therefore, it is preferable that the laminate further has a printed layer between the paper substrate and the resin layer.

[0049] Examples of resins constituting the resin layer include polyvinylidene chloride, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, nylon-based resins such as nylon 6, nylon 6,6, and nylon MXD6, and polyethylene terephthalate (PET). Among these, the resin constituting the resin layer preferably contains one or more selected from the group consisting of nylon-based resins and PET, and more preferably contains a nylon-based resin from the viewpoint of improving the puncture strength of the laminate and achieving a high melting point. If the resin constituting the resin layer has a high melting point, it is possible to suppress the phenomenon in which the resin layer melts during heat sealing, resulting in a deterioration in the appearance of the printed surface, or the resin layer adheres to the seal bar, resulting in a decrease in operability.

[0050] The method for laminating the paper substrate and the resin layer is not particularly limited, but from the viewpoint of ease of production, it is preferable to attach the resin layer and the paper substrate via an adhesive, or to laminate them, or to apply them in the form of a liquid paint, and it is more preferable to attach the film for the resin layer and the paper substrate via an adhesive. The adhesive for bonding the paper substrate and the resin layer is not particularly limited, and may be appropriately selected from known adhesives, and the components constituting the adhesive layer described above may also be used.

[0051] When the gas barrier laminate of this embodiment has a resin layer, the thickness of the resin layer is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more, more preferably 70 μm or less, even more preferably 50 μm or less, and still more preferably 30 μm or less. The thickness of the resin layer is preferably at least the above lower limit from the viewpoint of protecting the paper substrate and improving the water resistance of the gas barrier laminate, and is preferably at most the above upper limit from the viewpoint of recyclability.

[0052] <Content of each layer, and thickness or basis weight> The content of the gas barrier resin (preferably ethylene-vinyl alcohol copolymer) in the gas barrier layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more, of the solid content of the gas barrier layer, with the upper limit being 100% by mass. Furthermore, when the gas barrier layer contains an adhesion promoter, the content of the adhesion promoter (preferably polyethyleneimine resin) is preferably 0.5 parts by mass per 100 parts by mass of the gas barrier resin (preferably ethylene-vinyl alcohol copolymer). and more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less. Furthermore, when the gas barrier layer contains an adhesion promoter, the content of the adhesion promoter (preferably a polyethyleneimine resin) in the gas barrier layer is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more, even more preferably 3% by mass or more, and more preferably 10% by mass or less, and even more preferably 7% by mass or less. Furthermore, the coating amount (solid content) of the gas barrier layer is preferably 0.5 g / m ２ 5g / m or more ２ More preferably, it is 0.7 g / m or less. ２ More preferably, it is 3 g / m or more. ２

[0023] When the paper substrate contains a water repellent and a water-soluble binder is blended into the surface treatment liquid containing the water repellent, the blending amount of the water-soluble binder is preferably 10 parts by mass or more and 70 parts by mass or less, more preferably 15 parts by mass or more, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the water repellent. When a binder is blended into the surface treatment liquid, the blending amount of the binder is preferably 40 parts by mass or more and 90 parts by mass or less, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and even more preferably 80 parts by mass or less, relative to 100 parts by mass of the water repellent. The thickness of the sealant layer is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more, even more preferably 15 μm or more, and more preferably 70 μm or less, and even more preferably 40 μm or less. The coating amount (solid content) of the gas barrier layer is preferably 0.5 g / m ２ 5g / m or more ２ More preferably, it is 0.7 g / m or less. ２ More preferably, it is 3 g / m or more. ２ Furthermore, the basis weight of the paper substrate is preferably 20 g / m ２ More than 300g / m ２ More preferably, it is 30 g / m or less. ２ More preferably, 40 g / m ２ More preferably, it is 200 g / m or more. ２ More preferably 150 g / m or less ２ More preferably, 100 g / m or less ２ When the paper substrate contains a water repellent, the coating amount (solid content) of the surface treatment liquid containing the water repellent per side is preferably 0.5 g / m or less. ２ 4.0g / m or more ２ More preferably, it is 1.0 g / m or less. ２ More preferably, it is 3.0 g / m or more. ２Furthermore, when the gas barrier laminate of the present embodiment has a resin layer, the thickness of the resin layer is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more, more preferably 70 μm or less, even more preferably 50 μm or less, and still more preferably 30 μm or less.

[0053] <Method for manufacturing a gas barrier laminate> The gas barrier laminate of this embodiment has a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate laminated in this order. The method for laminating each layer is not particularly limited, but from the viewpoint of ease of manufacturing, it is preferable to attach them via an adhesive, to laminate them, or to apply them in the form of a liquid paint. Specifically, for example, a method can be mentioned in which a coating liquid for a gas barrier layer is applied to a resin film for a sealant layer and dried to form a gas barrier layer, an adhesive is applied to the gas barrier layer, and a paper substrate is attached via an adhesive layer composed of the adhesive to manufacture a gas barrier laminate. Furthermore, a film for a resin layer can be laminated via an adhesive on the surface of the paper substrate of the gas barrier laminate manufactured as described above.

[0054] The coating equipment for applying the coating liquid is not particularly limited, and known equipment may be used, such as a blade coater, a bar coater, an air knife coater, a slit die coater, a gravure coater, a microgravure coater, and a gate roll coater.

[0055] The drying equipment for drying the coating layer is not particularly limited, and known equipment can be used. Examples of drying equipment include a hot air dryer, an infrared dryer, a gas burner, and a hot plate. The drying temperature can be appropriately set taking into account the drying time, etc.

[0056] The solvent for the coating liquid of each layer is not particularly limited, and may be water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone, toluene, etc. Among these, water is preferred as the dispersion medium for the coating liquid of each layer from the viewpoint of avoiding the problem of volatile organic solvents.

[0057] <Physical Properties of Gas Barrier Laminate> (Edge Wick Value) The gas barrier laminate according to this embodiment has an Edge Wick value of 1 g / 1000 mm with water at 23° C. after a contact time of 1 hour. ２ Preferably, it is 0.8 g / 1000 mm or less. ２ Less than or equal to 0.6 g / 1000 mm, more preferably 0.6 g / 1000 mm ２ The lower limit is not particularly limited, but is, for example, 0.1 g / 1000 mm ２ That's all. When the Edge Wick value of the gas barrier laminate according to this embodiment is within the above range, when it is made into a packaging bag, penetration of water into the paper substrate is suppressed even when it comes into contact with water. As a result, the shape of the packaging bag can be maintained, poor appearance of the packaging bag due to discoloration of the paper substrate can be suppressed, and the phenomenon of peeling between the paper substrate and the sealant layer (delamination) can be suppressed. Therefore, a gas barrier laminate having an Edge Wick value within the above range can be used even in situations where it comes into contact with water. The Edge Wick value of the gas barrier laminate is measured by the method described in the Examples. The Edge Wick value can be adjusted by the treatment of the paper substrate as described above.

[0058] (Oxygen Permeability) The lower the oxygen permeability of the gas barrier laminate, the less oxygen is transmitted, which is preferable. Specifically, the oxygen permeability at 23°C and 50% RH is 5 mL / (m ２ ·day·atm) or less, preferably 3 mL / (m ２ ·day·atm) or less, and the lower limit is not particularly limited, but for example, 0.1 mL / (m ２ The oxygen permeability of the gas barrier laminate is measured in accordance with JIS K 7126-2:2006.

[0059] (Heat seal strength) The heat seal strength between the sealant layers of two gas barrier laminates is preferably 5 N / 15 mm or more, more preferably 10 N / 15 mm or more, and the upper limit is not particularly limited, but is, for example, 20 N / 15 mm or less. If the heat seal strength is within the above range, even if two gas barrier laminates are peeled apart, the peeling occurs within the paper base material, so that packaging bags made using the gas barrier laminate of this embodiment are safe even for food, etc. The heat seal strength is measured by the method described in the examples.

[0060] (Puncture Strength) The puncture strength of the gas barrier laminate is appropriately selected depending on the application of the gas barrier laminate, but from the viewpoint of obtaining appropriate strength when made into a packaging bag, it is preferably 2 N or more, more preferably 4 N or more, and the upper limit is not particularly limited, but is, for example, 20 N or less. The puncture strength of the gas barrier laminate is measured in accordance with JIS Z 1707:2019. The puncture strength of the gas barrier laminate can be adjusted by the basis weight of the paper substrate, the type and thickness of the resin layer, etc.

[0061] The gas barrier laminate of this embodiment has excellent gas barrier properties and can be used in situations where it comes into contact with water (e.g., in a lunch box, in a bathroom, etc.). Therefore, a packaging material made using the gas barrier laminate of this embodiment can be suitably used, for example, as packaging bags, preferably small bags (small-volume filled bags), for food, daily necessities, medical supplies, electronic components, etc. The contents to be filled into the packaging bag may be any liquid, solid, or gel, and examples include condiments such as soy sauce, mayonnaise, ketchup, and dressing; and toiletries such as shampoo, conditioner, and body soap. Therefore, according to the present invention, a packaging bag made using the gas barrier laminate is provided. The packaging bag can be obtained, for example, by folding the gas barrier laminate of this embodiment or by stacking two sheets together so that the sealant layers face each other, and then heat-sealing the peripheral edges. Examples of the shape of the packaging bag include a standing pouch type, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a palm seal type (pillow seal type), a pleated seal type, a flat bottom seal type, a square bottom seal type, and a gusset type.

[0062] The measurement and evaluation methods used for the gas barrier laminate are shown below. Unless otherwise specified, measurements were performed in an environment of a temperature of 23°C ± 1°C and a relative humidity of 50 ± 2% as specified in JIS P 8111:1998. In the examples and comparative examples, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0063] [Measurement and Evaluation] <Edge Wick Value> The Edge Wick value of the gas barrier laminate was measured as follows. The thickness of the paper used in the gas barrier laminate was measured. The gas barrier laminate was pouched using a laminator (trade name: LFA441D, manufactured by Iris Ohyama Co., Ltd.) and a laminate film (trade name: LFT-A4300, manufactured by Iris Ohyama Co., Ltd.), and cut on all four sides to a length of 9 cm and a width of 6 cm to obtain a sample. At this time, the length of the sample was aligned with the papermaking direction (machine direction). The sample was left to stand for 4 hours or more in an environment at a temperature of 23°C and a relative humidity of 50%, and the mass was measured. After that, the sample was immersed in ion-exchanged water at 23°C for 60 minutes. The sample was removed from the ion-exchanged water, and the ion-exchanged water adhering to the surface was removed, and the mass of the sample was immediately measured. The Edgewick value (g / 1000 mm) for water at 23°C after 1 hour of contact was calculated from the increase in the sample mass (mass after immersion in ion-exchanged water - mass before immersion) and the cross-sectional area of ​​the paper in contact with ion-exchanged water (thickness of the base paper x circumference of the sample). ２ ) was calculated.

[0064] <Oxygen Permeability> The oxygen permeability of the gas barrier laminate was measured at a temperature of 23°C and a relative humidity of 50% using an oxygen permeability measuring device (product name: OX-TRAN2 / 22, manufactured by MOCON Corporation) in accordance with JIS K 7126-2:2006.

[0065] <Heat Seal Strength> The heat seal strength of the gas barrier laminate was measured as follows. Two gas barrier laminates were stacked together with the sealant layers in contact, and heat-sealed using a heat seal tester (product name: TP-701-B, manufactured by Tester Sangyo Co., Ltd.) at 140°C, 0.2 MPa, and 1 second. The heat-sealed test piece was left to stand for at least 4 hours in an environment of 23°C and 50% relative humidity. The heat-sealed test piece was then cut into a 15 mm width and subjected to T-peel at a tensile speed of 300 mm / min using a tensile tester. The recorded maximum load was taken as the heat seal strength. The peeled surface was visually inspected to evaluate the presence or absence of fracture in the paper substrate. If fracture occurred within the paper substrate, the gas barrier laminate had excellent heat sealability and was safe even when used as a packaging bag for food, etc.

[0066] <Puncture Strength> The puncture strength of the gas barrier laminate was measured in accordance with JIS Z 1707:2019.

[0067] <Water Resistance> The water resistance of the gas barrier laminate was evaluated based on the change in appearance after the gas barrier laminate was immersed in water. Specifically, the evaluation was performed as follows. The gas barrier laminate was cut into two samples measuring 9 cm in length and 6 cm in width. The longitudinal direction of the samples was aligned with the papermaking direction (machine direction). Two gas barrier laminates were stacked together so that the sealant layers were in contact with each other, and four edges of the samples were heat-sealed at 140°C, 0.2 MPa, and 1 second using a heat seal tester (product name: TP-701-B, manufactured by Tester Sangyo Co., Ltd.) to prepare a four-sided sealed bag. The sample was immersed in ion-exchanged water at 23°C for 60 minutes, and the condition of the sample was observed and evaluated according to the following criteria: A: No water penetration was observed, indicating excellent water resistance. B: Water penetration was observed, indicating poor water resistance.

[0068] <Bag-making processability> The bag-making processability of the gas barrier laminate was evaluated based on the appearance of pillow bags made from the gas barrier laminate using a pillow bag making machine. Specifically, the evaluation was as follows. A roll of the gas barrier laminate with a width of 320 mm was used to make a pillow bag with a pillow packaging machine, producing a pillow bag with a width of 140 mm and a length of 200 mm. The appearance of the pillow bag was checked and evaluated according to the following criteria. A: Clean with few wrinkles B: No problems in use but with many wrinkles

[0069] Example 1 <Production of Paper Base> 100 parts of hardwood kraft pulp was blended with 0.4 parts of a wet strength agent (PAE, trade name: Arafix 255, manufactured by Arakawa Chemical Industries, Ltd.), 0.3 parts of a dry strength agent (trade name: Polystron 117, manufactured by Arakawa Chemical Industries, Ltd.), and 0.8 parts of aluminum sulfate to prepare a paper base material. A paper base was then produced on a Fourdrinier multi-cylinder paper machine. A surface treatment solution containing 100 parts (solids) of a paraffin wax compound (trade name: WR3906, manufactured by Seiko PMC Corporation) as a water repellent, 25 parts (solids) of polyvinyl alcohol (PVA, manufactured by Kuraray Co., Ltd.), and 70 parts (solids) of a styrene-butadiene copolymer latex (trade name: OJ2000H, manufactured by JSR Corporation) as an anti-slip agent, and 2.0 g / m2 of a surface treatment solution was applied to the paper using a gate roll coater and a size press to a thickness of 2.0 g / m2 per side in terms of solids. ２ The coating was applied to a paper substrate so as to have a basis weight of 52 g / m ２ This was designated as paper substrate A. <Preparation of Coating Solution for Gas Barrier Layer> An ethylene-vinyl alcohol copolymer solution (trade name: Eversolve #10, manufactured by Nippon Cima Co., Ltd.) was used. When a coating film of 10 μm in thickness was formed on a low-density polyethylene film of 30 μm in thickness, the oxygen permeability at 23° C. and 50% RH measured in accordance with JIS K 7126-2:2006 was 50 mL / (m ２Coating Solution A for gas barrier layer (solids concentration 10%) was prepared by mixing 100 parts (solids content) of polyethyleneimine (trade name: Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) and 5 parts (solids content) of polyethyleneimine (trade name: Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.). <Coating onto sealant film> Coating Solution A for gas barrier layer was applied to one side of a sealant film (linear low-density polyethylene film, trade name: LL-XMTL, thickness 20 μm, manufactured by Futamura Chemical Co., Ltd.) that had been subjected to corona treatment, so that the coating amount after drying was 1 g / m. ２ The surface of the sealant film coated with the gas barrier layer coating liquid, i.e., the gas barrier layer, was coated with an adhesive (a mixture of 10 parts "DIC Dry LX-500" and 1 part "DIC Dry KW-75", manufactured by DIC Graphics Corporation) in a coating amount of 4 g / m2 after drying. ２ The coating was dried at 80°C for 10 seconds to form an adhesive layer, and then paper substrate A was attached to obtain a gas barrier laminate (sealant layer / gas barrier layer / adhesive layer / paper substrate). The measurement and evaluation results are shown in Table 1.

[0070] Example 2 The coating amount of the coating liquid for the gas barrier layer of Example 1 was 2 g / m ２ Except for the above, a gas barrier laminate was obtained in the same manner as in Example 1. The measurement and evaluation results are shown in Table 1.

[0071] Example 3 An adhesive (a mixture of 10 parts Dickdry LX-500 and 1 part Dickdry KW-75, manufactured by DIC Graphics Corporation) was applied to one corona-treated surface of a nylon film (trade name: Emblem ON, thickness 15 μm, manufactured by Unitika Ltd.) in a coating amount of 4 g / m after drying. ２ The coating was dried at 80°C for 10 seconds, and then laminated to the paper substrate surface of a gas barrier laminate obtained in the same manner as in Example 1 to obtain a gas barrier laminate (sealant layer / gas barrier layer / adhesive layer / paper substrate / adhesive layer / resin layer). The measurement and evaluation results are shown in Table 1.

[0072] Example 4: Paper substrate basis weight 64 g / m ２A paper base B was obtained in the same manner as in Example 1, except that the paper base B was used, and a gas barrier laminate was obtained in the same manner as in Example 1. The measurement and evaluation results are shown in Table 1.

[0073] Example 5: Paper substrate basis weight: 128 g / m ２ A paper base C was obtained in the same manner as in Example 1, except that the paper base C was used, and a gas barrier laminate was obtained in the same manner as in Example 1, except that the paper base C was used. The measurement and evaluation results are shown in Table 1.

[0074] Example 6 Coating Solution B for gas barrier layer (solids concentration 10%) was prepared in the same manner as in Example 1, except that the blending amount of polyethyleneimine in Coating Solution A for gas barrier layer in Example 1 was set to 0 parts, and a gas barrier laminate was obtained in the same manner as in Example 1, except that Coating Solution B for gas barrier layer was used. The measurement and evaluation results are shown in Table 1.

[0075] Example 7 To 20 parts (solids) of an aqueous dispersion of a layered inorganic compound (swellable mica, trade name: NTS-10NC, manufactured by Topy Industries, Ltd.), 15 parts (solids) of a self-emulsifying emulsion of ethylene-acrylic acid copolymer (trade name: ZAIKXEN AC, manufactured by Sumitomo Seika Chemicals Co., Ltd.) was added with stirring, and a self-emulsifying aqueous emulsion of hydroxy polyurethane (trade name: HPU-W013A, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) was further added. When a 10 μm thick coating film was formed on a 30 μm thick low-density polyethylene film, the oxygen permeability at 23°C and 50% RH measured in accordance with JIS K 7126-2:2006 was 50 mL / (m ２ 80 parts (solids content) of a cation-modified polyamide resin (trade name: Sumirez Resin SPI-203(50)H, manufactured by Taoka Chemical Co., Ltd.) was added thereto and stirred. Furthermore, ethylene-modified polyvinyl alcohol (trade name: EXCEVAL RS-1717, manufactured by Kuraray Co., Ltd.) was added thereto and stirred. When a 10 μm thick coating film was formed on a 30 μm thick low-density polyethylene film, the oxygen permeability at 23°C and 50% RH measured in accordance with JIS K 7126-2:2006 was 50 mL / (m ２5 parts (solids content) of an aqueous solution prepared by dissolving 2,4-dimethylaminobenzoate (2,4-dimethylaminobenzoate) in water to a solids concentration of 10% by mass was added. 0.5 parts of a 25% by mass aqueous ammonia solution was then added and stirred to prepare Coating Solution C for gas barrier layer (solids concentration: 15%). A gas barrier laminate was obtained in the same manner as in Example 2, except that Coating Solution C for gas barrier layer was used. The measurement and evaluation results are shown in Table 1.

[0076] Comparative Example 1: A paper substrate was prepared in the same manner as in Example 1, except that the surface treatment liquid was not applied to the paper substrate. ２ A gas barrier laminate was obtained in the same manner as in Example 1, except that paper base D was used. The measurement and evaluation results are shown in Table 1.

[0077] Comparative Example 2 A gas barrier laminate was obtained in the same manner as in Example 1, except that the gas barrier layer coating liquid was not applied and the gas barrier layer was not formed. The measurement and evaluation results are shown in Table 1.

[0078]

[0079] As can be seen from Table 1, the film has a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, the gas barrier layer contains a gas barrier resin, and the oxygen permeability at 23°C and 50% RH is 5 mL / (m ２ · day · atm) or less, and the Edgewick value in water at 23 ° C. after a contact time of 1 hour is 1 g / 1000 mm ２ The gas barrier laminates according to Examples 1 to 7 below have excellent gas barrier properties and water resistance, and are therefore usable in applications involving contact with water. Furthermore, it has been found that packaging bags made using the gas barrier laminates of the present embodiment are also excellent in bag-making suitability by adjusting the basis weight of the paper substrate.

Claims

1. A film having a sealant layer, a gas barrier layer, an adhesive layer, and a paper substrate in this order, the gas barrier layer containing a gas barrier resin, and an oxygen permeability of 5 mL / (m at 23°C and 50% RH. ２ ·day·atm) or less, and the Edgewick value in water at 23°C for a contact time of 1 hour is 1 g / 1000 mm ２ A gas barrier laminate comprising:

2. The gas barrier laminate according to claim 1, which has a resin layer on the side of the paper substrate opposite to the side having the sealant layer, the gas barrier layer and the adhesive layer.

3. The gas barrier laminate according to claim 1 or 2, wherein the paper substrate is provided with a water repellent agent.

4. The gas barrier laminate according to any one of claims 1 to 3, wherein the paper substrate contains paraffin wax.

5. The gas barrier laminate according to any one of claims 1 to 4, wherein the gas barrier resin comprises at least one selected from the group consisting of ethylene-vinyl alcohol copolymers and polyurethane resins.

6. The gas barrier laminate according to any one of claims 1 to 5, wherein the content of the gas barrier resin in the gas barrier layer is 70 mass % or more.

7. The gas barrier laminate according to any one of claims 1 to 6, wherein the gas barrier layer further comprises an adhesion promoter.

8. The gas barrier laminate according to claim 7, wherein the adhesion promoter comprises a polyethyleneimine resin.

9. The gas barrier laminate according to claim 7 or 8, wherein the content of the adhesion imparting agent in the gas barrier layer is 0.5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the gas barrier resin.

10. The gas barrier laminate according to any one of claims 7 to 9, wherein the content of the adhesion promoter in the gas barrier layer is from 0.5% by mass to 15% by mass.

11. The coating weight of the gas barrier layer is 0.5 g / m ２ 3g / m or more ２ The gas barrier laminate according to any one of claims 1 to 10, wherein:

12. The basis weight of the paper base material is 20 g / m ２ More than 200g / m ２ The gas barrier laminate according to any one of claims 1 to 11, wherein:

13. The gas barrier laminate according to any one of claims 1 to 12, wherein the content of the paper base material in the gas barrier laminate is 50 mass % or more.

14. A packaging bag comprising the gas barrier laminate according to any one of claims 1 to 13.

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