Gas barrier laminate and packaging bag

Abstract

A gas barrier laminate equipped, in this order, with a paper substrate, an anchor coat layer comprising a first polyolefin having a polar group, a vapor-deposited layer, and an overcoat layer comprising a second polyolefin having a polar group, wherein a layer containing a polyvinyl alcohol-based resin is provided between the paper substrate and the anchor coat layer or between the anchor coat layer and the vapor-deposited layer.

Description

[Technical Field]

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

[0002] Packaging materials are used in many fields, including food, beverages, pharmaceuticals, and chemicals, depending on the contents. Packaging materials are required to have gas barrier properties that prevent the permeation of oxygen and water vapor, which can cause deterioration of the contents.

[0003] In recent years, growing environmental awareness stemming from the problem of marine plastic waste and other issues has led to a growing trend toward a plastic-free society. From the perspective of reducing the amount of plastic material used, the use of paper instead of plastic materials has been considered in various fields. For example, Patent Document 1 listed below discloses a gas barrier laminate in which a barrier layer is laminated on paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-69783 Summary of the Invention [Problem to be solved by the invention]

[0005] Paper has the advantage of being easy to process due to its fold retention (also known as deadhold property). However, the inventors' investigations have revealed that there is still room for improvement in that cracks occur in the barrier layer and the gas barrier properties deteriorate when paper is used to make packaging bags with sharper folds (pillow packaging, three-side seal packaging, and gusset packaging).

[0006] Furthermore, from the perspective of the Law for Promoting Effective Utilization of Resources, it is required to reduce the amount of plastic materials used in gas barrier laminates as well.

[0007] The present invention has been made in view of the above-mentioned circumstances, and aims to provide a gas barrier laminate that has the fold retention characteristic of paper, has sufficient gas barrier properties even after being folded, and contributes to reducing the amount of plastic material used, as well as a packaging bag including the gas barrier laminate. [Means for solving the problem]

[0008] The present invention provides a gas barrier laminate comprising, in this order, a paper substrate, an anchor coat layer containing a first polyolefin having a polar group, a vapor deposition layer, and an overcoat layer containing a second polyolefin having a polar group, with a layer containing a polyvinyl alcohol-based resin between the paper substrate and the anchor coat layer or between the anchor coat layer and the vapor deposition layer.

[0009] The first polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0010] The second polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0011] The first polyolefin having a polar group may be a copolymer of an acrylic acid ester and maleic anhydride.

[0012] The first polyolefin having a polar group may be an ethylene-vinyl acetate copolymer.

[0013] The first polyolefin having a polar group may be an ethylene-glycidyl methacrylate copolymer.

[0014] The second polyolefin having a polar group may be a copolymer of an acrylic acid ester and maleic anhydride.

[0015] The second polyolefin having a polar group may be an ethylene-vinyl acetate copolymer.

[0016] The second polyolefin having a polar group may be an ethylene-glycidyl methacrylate copolymer.

[0017] The thickness of the anchor coat layer may be 1 μm or more and 5 μm or less.

[0018] The thickness of the layer containing the polyvinyl alcohol resin may be 1 μm or more and 5 μm or less.

[0019] The thickness of the deposited layer may be 30 nm or more and 100 nm or less.

[0020] The thickness of the overcoat layer may be 2 μm or more and 10 μm or less.

[0021] The thickness of the paper substrate may be 30 μm or more and 100 μm or less, and the thickness of the paper substrate may be 70% or more of the total thickness of the gas barrier laminate.

[0022] The weight of the paper may be 50% by mass or more based on the weight of the entire gas barrier laminate.

[0023] The present invention also provides a packaging bag comprising the gas barrier laminate according to the present invention.

[0024] The packaging bag may have a folded portion. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a gas barrier laminate and a packaging bag including the same, which have the fold retention properties that are characteristic of paper and have sufficient gas barrier properties even after being folded, and which contribute to reducing the amount of plastic material used. [Brief explanation of the drawings]

[0026] [Figure 1]1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment of the present invention. [Figure 2] 1 is a perspective view showing a packaging bag according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings where necessary, but the present invention is not limited to the following embodiments.

[0028] <Gas barrier laminate> FIG. 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. A gas barrier laminate 10 according to one embodiment comprises, in this order, a paper substrate 1, an anchor coat layer 2, a layer 3 containing a polyvinyl alcohol-based resin, a vapor-deposited layer 4, and an overcoat layer 5. Because both the anchor coat layer 2 and the layer 3 containing a polyvinyl alcohol-based resin have excellent adhesion to the paper substrate 1 and the vapor-deposited layer 4, the order of the anchor coat layer 2 and the layer 3 containing a polyvinyl alcohol-based resin may be reversed. That is, the gas barrier laminate may comprise, in this order, the paper substrate 1, the layer 3 containing a polyvinyl alcohol-based resin, the anchor coat layer 2, the vapor-deposited layer 4, and the overcoat layer 5. The anchor coat layer 2 contains a first polyolefin having a polar group, and the overcoat layer 5 contains a second polyolefin having a polar group.

[0029] [Paper base material] The paper substrate 1 is not particularly limited and may be appropriately selected depending on the application of the packaging bag to which the gas barrier laminate 10 is applied. There are no particular limitations on the paper substrate 1 as long as it is made primarily of plant-derived pulp. Specific examples of the paper substrate 1 include fine paper, special fine paper, coated paper, art paper, cast-coated paper, construction paper, kraft paper, and glassine paper. The thickness of the paper substrate 1 may be, for example, 30 μm or more and 100 μm or less, or 30 μm or more and 70 μm or less. The thickness of the paper substrate may be 70% or more of the total thickness of the gas barrier laminate. If the thickness of the paper substrate is 70% or more of the total thickness of the gas barrier laminate, it can be said that the gas barrier laminate has excellent environmental compatibility.

[0030] The paper substrate 1 may have a coating layer provided at least on the side that contacts the anchor coat layer 2 described below. The coating layer prevents the anchor coat layer 2 from penetrating into the paper and also serves as a sealant that fills in unevenness in the paper, allowing the anchor coat layer to be formed uniformly and without defects. The coating layer may contain binder resins such as various copolymers such as styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, cellulose resins, paraffin (wax), and the like, and fillers such as clay, kaolin, calcium carbonate, talc, and mica.

[0031] The thickness of the clay coating layer is not particularly limited, but may be, for example, 1 to 10 μm, or 3 to 8 μm.

[0032] The weight of paper is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the weight of the entire gas barrier laminate. If the weight of paper is 50% by mass or more, based on the weight of the entire gas barrier laminate, the amount of plastic material used can be sufficiently reduced, the gas barrier laminate as a whole can be said to be made of paper, and recyclability is excellent.

[0033] [Anchor coat layer] The anchor coat layer 2 is provided on the surface of the paper substrate to improve adhesion between the paper substrate 1 and the layer 3 containing a polyvinyl alcohol-based resin, which will be described later, and to improve the gas barrier properties of the gas barrier laminate. Such an anchor coat layer 2 has excellent flexibility and can suppress cracking of the vapor-deposited layer, which will be described later, after bending (folding), and can improve adhesion between the anchor coat layer and the layer containing a polyvinyl alcohol-based resin. Furthermore, by including the above-mentioned polyolefin, it is possible to form a dense film due to carboxyl groups, etc., and a gas barrier laminate with excellent water vapor barrier properties can be obtained.

[0034] The first polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0035] The first polyolefin having a polar group may be a copolymer of ethylene or propylene with an unsaturated carboxylic acid (an unsaturated compound having a carboxyl group, such as acrylic acid, methacrylic acid, or maleic anhydride), an unsaturated carboxylic acid ester, or a salt of a carboxylic acid neutralized with a basic compound. Alternatively, a copolymer of ethylene or propylene with vinyl acetate, an epoxy compound, a chlorine compound, a urethane compound, or a polyamide compound may be used.

[0036] Specific examples of the first polyolefin having a polar group include a copolymer of an acrylic acid ester and maleic anhydride, an ethylene-vinyl acetate copolymer, and an ethylene-glycidyl methacrylate copolymer.

[0037] The anchor coat layer 2 may contain other components in addition to the first polyolefin, such as polyolefins other than the first polyolefin, silane coupling agents, organic titanates, polyacrylics, polyesters, polyurethanes, polycarbonates, polyureas, polyamides, polyimides, melamine, and phenols.

[0038] The content of the first polyolefin in the anchor coat layer 2 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0039] The thickness of the anchor coat layer 2 may be, for example, 1 μm or more, 2 μm or more, or 5 μm or less. If the thickness of the anchor coat layer 2 is 1 μm or more, the unevenness of the paper base material described above can be efficiently filled, and the layer containing a polyvinyl alcohol resin and the vapor deposition layer described below can be laminated uniformly. Furthermore, if the thickness of the anchor coat layer 2 is 5 μm or less, the above layers can be laminated uniformly while keeping costs down.

[0040] The anchor coat layer 2 can be formed by applying a coating liquid containing the above-mentioned polyolefin and a solvent to a paper substrate and drying it. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used alone or in combination. Among these, from the viewpoint of properties, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from the viewpoint of the environment, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.

[0041] [Layer containing polyvinyl alcohol-based resin] The layer 3 containing a polyvinyl alcohol-based resin is provided on the surface of the anchor coat layer to improve adhesion between the anchor coat layer 2 and the vapor-deposited layer 4 described below, and to improve the gas barrier properties (particularly the oxygen barrier properties) of the gas barrier laminate. Examples of polyvinyl alcohol-based resins include fully saponified polyvinyl alcohol resins, partially saponified polyvinyl alcohol resins, modified polyvinyl alcohol resins, and ethylene-vinyl alcohol copolymer resins. The degree of polymerization of the polyvinyl alcohol-based resin is preferably 300 or more and 1500 or less. If the degree of polymerization is 300 or more, the gas barrier laminate will have good barrier properties and flex resistance, and if the degree of polymerization is 1500 or less, the viscosity of a coating liquid of the polyvinyl alcohol-based resin described below will be low, improving coatability.

[0042] The polyvinyl alcohol resin-containing layer 3 can be provided by applying a coating liquid containing the above-mentioned polyvinyl alcohol resin and a solvent to the paper substrate 1 and drying it. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide, with mixed solvents of water and alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol being particularly preferred. The coating liquid may also contain additives such as surfactants, preservatives, storage stabilizers, silane coupling agents, and organic titanates.

[0043] Such a layer 3 containing a polyvinyl alcohol-based resin has excellent flexibility, can suppress cracking of the vapor-deposited layer described below after bending (folding), and can improve adhesion between the vapor-deposited layer and the layer containing a polyvinyl alcohol-based resin.

[0044] The thickness of the layer 3 containing a polyvinyl alcohol-based resin may be, for example, 1 μm or more, 2 μm or more, or 5 μm or less. If the thickness is 1 μm or more, the vapor-deposited layer described below can be uniformly laminated. On the other hand, if the thickness is 5 μm or less, the vapor-deposited layer can be uniformly laminated while keeping costs down.

[0045] [Vapour-deposited layer] The vapor-deposited layer 4 is a layer obtained by vapor-depositing a metal or an inorganic compound. The vapor-deposited layer may be obtained by vapor-depositing aluminum, or may be obtained by vapor-depositing aluminum oxide (AlO x ), silicon oxide (SiO x ) etc. may also be included.

[0046] The thickness of the vapor-deposited layer 4 may be appropriately set depending on the intended use, but is preferably 30 nm or more, or 50 nm or more, and may be 100 nm or less, or 80 nm or less. A thickness of 30 nm or more makes it easy to ensure sufficient continuity of the vapor-deposited layer 4, while a thickness of 100 nm or less makes it easy to sufficiently suppress the occurrence of curling and cracking, and to easily achieve sufficient gas barrier performance and flexibility.

[0047] The deposition layer 4 is preferably formed by a vacuum deposition method from the viewpoint of oxygen gas barrier performance and film uniformity. There are known deposition methods such as vacuum deposition, sputtering, and chemical vapor deposition (CVD), but vacuum deposition is preferred due to its high deposition rate and high productivity. Among vacuum deposition methods, deposition by electron beam heating is particularly effective because the deposition rate can be easily controlled by the irradiation area and electron beam current, and the temperature of the deposition material can be increased or decreased in a short time.

[0048] [Overcoat layer] The overcoat layer 5 is provided on the surface of the vapor-deposited layer 4 so as to be in contact with the vapor-deposited layer 4, and contains a second polyolefin having a polar group.

[0049] The second polyolefin having a polar group may have at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0050] The second polyolefin having a polar group may be a copolymer of ethylene or propylene with an unsaturated carboxylic acid (an unsaturated compound having a carboxyl group, such as acrylic acid or methacrylic acid), an unsaturated carboxylic acid ester, or a salt of a carboxylic acid neutralized with a basic compound. Alternatively, a copolymer of ethylene or propylene with vinyl acetate, an epoxy compound, a chlorine compound, a urethane compound, a polyamide compound, or the like may be used.

[0051] Specifically, the second polyolefin having a polar group may be a copolymer of an acrylic acid ester and maleic anhydride, an ethylene-vinyl acetate copolymer, an ethylene-glycidyl methacrylate copolymer, or the like.

[0052] Such an overcoat layer 5 has excellent flexibility, can suppress cracking of the vapor-deposited layer after bending (folding), and has excellent adhesion to the vapor-deposited layer. Furthermore, by including the second polyolefin described above, a gas barrier laminate with excellent water vapor barrier properties can be obtained. Furthermore, by including the second polyolefin described above, the overcoat layer 5 can also function as a heat seal layer, so there is no need to provide a separate heat seal layer.

[0053] The overcoat layer 5 may contain other components in addition to the second polyolefin, such as a silane coupling agent, organic titanate, polyacrylic, polyester, polyurethane, polycarbonate, polyurea, polyamide, polyolefin emulsion, polyimide, melamine, and phenol.

[0054] The content of the second polyolefin in the overcoat layer 5 may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0055] The thickness of the overcoat layer 5 may be, for example, 2 μm or more, 3 μm or more, 10 μm or less, 8 μm or less, or 5 μm or less. If the thickness of the overcoat layer 5 is 2 μm or more, it can fully fulfill its role as the heat seal layer described above. Furthermore, if the thickness of the overcoat layer 5 is 10 μm or less, it can fully fulfill its adhesiveness to the vapor deposition layer and its barrier properties while keeping costs down.

[0056] The overcoat layer 5 can be formed by applying a coating liquid containing the polyolefin and a solvent to the vapor-deposited layer and drying it. Examples of solvents contained in the coating liquid include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used alone or in combination. Among these, from the viewpoint of properties, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred. Furthermore, from the viewpoint of environmental friendliness, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.

[0057] The first polyolefin and the second polyolefin contained in the anchor coat layer 2 and the overcoat layer 5, respectively, may be the same or different, but considering ease of production, it is preferable that they are the same.

[0058] The gas barrier laminate according to this embodiment can exhibit sufficient gas barrier properties. In this specification, gas barrier properties refer to a sufficiently low water vapor permeability and oxygen permeability. The gas barrier laminate according to this embodiment has a water vapor permeability of 2 g / m at 40°C and 90% RH. 2 / d or less. Depending on the type of contents, this value may be as low as 20 g / m 2 The gas barrier laminate according to this embodiment may have an oxygen permeability of 2 cc / m or less at 30°C and 70% RH. 2 / d / atm or less is preferable. Depending on the type of contents, this value may be as low as 30cc / m 2 It may be less than / d / atm.

[0059] Furthermore, the gas barrier laminate according to this embodiment can exhibit sufficient gas barrier properties even after being folded. The gas barrier laminate according to this embodiment has a water vapor permeability of 3 g / m2 at 40°C and 90% RH, measured by folding the laminate with the paper substrate facing outward, rolling a 600 g roller over it once, opening the fold, and then measuring. 2 / d or less, and the oxygen permeability at 30°C and 70% RH is 3 cc / m 2 In addition, the paper substrate is placed inside, and a 600 g roller is rolled over it once, and the fold is opened and measured. The water vapor permeability at 40°C and 90% RH is 3 g / m or less. 2 / d or less, and the oxygen permeability at 30°C and 70% RH is 3 cc / m 2 It is preferable that the temperature is / d / atm or less.

[0060] Although one embodiment of the gas barrier laminate according to this embodiment has been described above, the present invention may also include other gas barrier laminates. For example, the layer containing the polyvinyl alcohol-based resin may be disposed between the paper substrate and the anchor coat layer. That is, the layer containing the polyvinyl alcohol-based resin may be disposed between the paper substrate and the anchor coat layer, or between the anchor coat layer and the vapor-deposited layer.

[0061] <Packaging bag> 2 is a perspective view showing a gusset bag 20 made of a gas barrier laminate 10. A packaging bag is produced by sealing the opening at the top of the gusset bag 20. The gusset bag 20 has portions where the gas barrier laminate 10 is folded (folded portions B1, B2). Folded portion B1 is a portion where the gas barrier laminate 10 is folded in a valley direction when viewed from the innermost layer side, while folded portion B2 is a portion where the gas barrier laminate 10 is folded in a mountain direction when viewed from the innermost layer side.

[0062] The packaging bag may be formed into a bag shape by folding one gas barrier laminate in half so that the overcoat layers 5 face each other, then folding it appropriately into the desired shape and heat sealing it, or may be formed into a bag shape by stacking two gas barrier laminates so that the overcoat layers 5 face each other, and then heat sealing it.

[0063] In the packaging bag according to this embodiment, the heat seal strength may be 2 N or more, or may be 4 N or more. The upper limit of the heat seal strength is not particularly limited, but may be, for example, 10 N or less.

[0064] Here, the heat seal strength was measured by stacking two gas barrier laminates 10 with the polyolefin-containing layers 3 facing each other, heat sealing them using a heat sealer under conditions of 120°C, 0.2 MPa, and 1 second, cutting out a 15 mm wide strip from each piece, and measuring the maximum load when T-peeling at a peeling speed of 300 mm / min.

[0065] The packaging bag can contain contents such as food, medicine, etc. It is particularly suitable for containing food such as sweets. The packaging bag according to this embodiment can maintain high gas barrier properties even when it has a shape with a folded portion.

[0066] In this embodiment, a gusset bag is given as an example of a packaging bag, but the gas barrier laminate according to this embodiment may be used to produce, for example, a pillow bag, a three-side sealed bag or a standing pouch. [Example]

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0068] <Preparation of gas barrier laminate> Example 1 A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) using a bar coater and dried in an oven to form an anchor coat layer. The layer thickness was 3 μm. Next, a coating solution containing polyvinyl alcohol resin (a polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 500 dissolved in a water / IPA solution at a solids concentration of 10% by mass) was applied to the anchor coat layer using a bar coater and dried in an oven to form a polyvinyl alcohol resin-containing layer. The layer thickness was 1 μm. Next, aluminum was vapor-deposited on the polyvinyl alcohol resin-containing layer. The thickness of the vapor-deposited aluminum layer was 50 nm. A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was then applied to the vapor-deposited layer using a bar coater and dried in an oven to form an overcoat layer, resulting in a gas barrier laminate. The thickness of the polyolefin-containing layer was 3 μm. The weight of paper in the gas barrier laminate was 81 mass %.

[0069] Example 2 A gas barrier laminate was obtained in the same manner as in Example 1, except that the thickness of the anchor coat layer was 1 μm and the thickness of the layer containing a polyvinyl alcohol resin was 5 μm. The weight of paper in the gas barrier laminate was 78 mass %.

[0070] Example 3 Except for changing the thickness of the anchor coat layer to 5 μm, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 78 mass %.

[0071] Example 4 Except for changing the thickness of the vapor-deposited layer to 30 nm, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 81 mass %.

[0072] Example 5 Except for changing the thickness of the vapor-deposited layer to 100 nm, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 81 mass %.

[0073] Example 6 Except for changing the thickness of the overcoat layer to 2 μm, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 82 mass %.

[0074] Example 7 Except for changing the thickness of the overcoat layer to 10 μm, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 72 mass %.

[0075] Example 8 Except for using paper (clay-coated paper, paper thickness: 30 μm, clay coating layer thickness: 5 μm), a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 71 mass %.

[0076] Example 9 A gas barrier laminate was obtained in the same manner as in Example 1, except that paper (clay-coated paper, paper thickness: 100 μm, clay coating layer thickness: 5 μm) was used. The weight of paper in the gas barrier laminate was 90 mass %.

[0077] Example 10 A gas barrier laminate was obtained in the same manner as in Example 1, except that the vapor-deposited layer was made of silica and had a thickness of 30 nm. The weight of paper in the gas barrier laminate was 82 mass %.

[0078] Example 11 A gas barrier laminate was obtained in the same manner as in Example 1, except that the vapor-deposited layer was made of alumina and had a thickness of 30 nm. The weight of paper in the gas barrier laminate was 81 mass %.

[0079] Example 12 A gas barrier laminate was obtained in the same manner as in Example 1, except that a polyolefin resin containing a copolymer of acrylic acid ester and maleic anhydride (trade name: Bondine HX-8290, manufactured by Arkema) was neutralized with triethylamine in a water / IPA mixed solvent to prepare a coating liquid, which was then coated with a bar coater to form an anchor coat layer.

[0080] Example 13 A polyolefin resin containing a copolymer of acrylic acid ester and maleic anhydride (trade name: Bondine HX-8290, manufactured by Arkema) was neutralized with triethylamine in a water / IPA mixed solvent to prepare a polyolefin aqueous dispersion. The resulting coating liquid was applied using a bar coater and dried in an oven to prepare an overcoat layer, and a gas barrier laminate was obtained in the same manner as in Example 1.

[0081] Example 14 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid consisting of an ethylene-vinyl acetate copolymer (product name: Chemipearl V300, manufactured by Mitsui Chemicals) was applied using a bar coater and dried in an oven to form an anchor coat layer.

[0082] Example 15 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid consisting of an ethylene-vinyl acetate copolymer (product name: Chemipearl V300, manufactured by Mitsui Chemicals) was applied using a bar coater and dried in an oven to form an overcoat layer.

[0083] Example 16 A gas barrier laminate was obtained in the same manner as in Example 1, except that an ethylene-glycidyl methacrylate copolymer coating solution (product name: Sepolsion G515, manufactured by Sumitomo Chemical) was applied using a bar coater and dried in an oven to form an anchor coat layer.

[0084] Example 17 A gas barrier laminate was obtained in the same manner as in Example 1, except that an ethylene-glycidyl methacrylate copolymer coating solution (product name: Sepolsion G515, manufactured by Sumitomo Chemical) was applied using a bar coater and dried in an oven to form an overcoat layer.

[0085] Example 18 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid containing a carboxyl group salt (product name: Chemipearl S100, manufactured by Mitsui Chemicals) was applied using a bar coater and dried in an oven to form an anchor coat layer.

[0086] Example 19 A coating solution containing polyvinyl alcohol resin, prepared by dissolving polyvinyl alcohol resin with a saponification degree of 98% and a degree of polymerization of 500 in a water / IPA solution at a solids concentration of 10% by mass, was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) using a bar coater and dried in an oven to form an anchor coat layer containing polyvinyl alcohol resin. The layer thickness was 1 μm. Next, a coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the anchor coat layer using a bar coater and dried in an oven to form a polyolefin layer containing a carboxyl group salt. The layer thickness was 3 μm. Next, aluminum was vapor-deposited on the layer containing the carboxyl group salt. The aluminum vapor-deposited layer was 50 nm thick. Then, a coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied onto the vapor-deposited layer using a bar coater and dried in an oven to form an overcoat layer, yielding a gas barrier laminate. The thickness of the polyolefin-containing layer was 3 μm. The weight of paper in the gas barrier laminate was 81% by mass.

[0087] (Comparative Example 1) Except for not providing a vapor-deposited layer, a gas barrier laminate was obtained in the same manner as in Example 1. The weight of paper in the gas barrier laminate was 81 mass %.

[0088] (Comparative Example 2) A coating solution containing an acrylic alkyd resin was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing an acrylic alkyd resin. The layer thickness was 4 μm. Subsequently, aluminum was vapor-deposited on this layer. The thickness of the aluminum vapor-deposited layer was 50 nm. A coating solution containing polyvinyl alcohol resin and TEOS was then applied to the aluminum vapor-deposited layer using a bar coater and dried in an oven to form a layer containing polyvinyl alcohol resin and TEOS. The layer thickness was 0.4 μm. A solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was then applied using a bar coater and dried in an oven to form a layer containing polyolefin, thereby obtaining a gas barrier laminate. The thickness of the polyolefin layer was 3 μm. The weight of paper in the gas barrier laminate was 80% by mass.

[0089] (Comparative Example 3) A coating liquid containing a urethane-curing acrylic resin was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing an ethylene-vinyl acetate copolymer. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited on the layer containing the ethylene-vinyl acetate copolymer. The thickness of the vapor-deposited aluminum layer was 50 nm. After that, a coating liquid containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the vapor-deposited layer using a bar coater and dried in an oven to form a layer containing polyolefin, thereby obtaining a gas barrier laminate. The thickness of the polyolefin layer was 3 μm. The weight of paper in the gas barrier laminate was 82% by mass.

[0090] Comparative Example 4 A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) using a bar coater and dried in an oven to form an anchor coat layer. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited on the anchor coat layer. The thickness of the aluminum vapor-deposited layer was 50 nm. A coating solution containing a polyvinyl alcohol resin was then applied to the aluminum vapor-deposited layer using a bar coater and dried in an oven to form a layer containing a polyvinyl alcohol resin. The layer thickness was 1 μm. A solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was then applied using a bar coater and dried in an oven to form an overcoat layer, yielding a gas barrier laminate. The thickness of the overcoat layer was 3 μm. The weight of paper in the gas barrier laminate was 81% by mass.

[0091] <Measurement of water vapor permeability> The water vapor permeability of the gas barrier laminates according to the examples and comparative examples was measured by the MOCON method. The measurement conditions were a temperature of 40°C and a relative humidity of 90%. A 600g roller was rolled at a speed of 300mm / min to create a crease in the gas barrier laminate, and the water vapor permeability of the gas barrier laminate after opening was also measured in the same manner. In Tables 1 to 7, "inward fold" refers to the gas barrier laminate after mountain folding as viewed from the paper substrate side, and "outward fold" refers to the gas barrier laminate after valley folding as viewed from the paper substrate side. Tables 1 to 7 show the results in units of [g / m 2 ·day].

[0092] <Oxygen permeability measurement> The oxygen permeability of the gas barrier laminates according to the examples and comparative examples was measured according to JIS K7126, method B (isobaric method). The measurement was carried out using an OXTRAN 2 / 20 measuring device manufactured by Nordrn Control at a temperature of 30°C and a relative humidity of 70%. The results are shown in Tables 1 to 7 in units of [cc / m 2 / d / atm].

[0093] <Heat seal strength measurement> Two gas barrier laminates were stacked with the polyolefin-containing layers facing each other and heat-sealed using a heat sealer at 120°C, 0.2 MPa, and 1 second. 15 mm wide strips were cut from the laminate and the maximum load measured when T-peeling at a peel rate of 300 mm / min. The results are shown in Tables 1 to 7 in units of N / 15 mm.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] [Table 5]

[0099] [Table 6]

[0100] [Table 7] [Explanation of symbols]

[0101] 1...paper base material, 2...anchor coat layer, 3...layer containing polyvinyl alcohol-based resin, 4...vapor deposition layer, 5...overcoat layer, 10...gas barrier laminate, 20...gusset bag, B1, B2...folded portion

Claims

1. A paper substrate; an anchor coat layer containing a first polyolefin having a polar group; a deposition layer; an overcoat layer comprising a second polyolefin having polar groups; In this order, a layer containing a polyvinyl alcohol-based resin is provided between the paper substrate and the anchor coat layer or between the anchor coat layer and the vapor-deposited layer; The thickness of the anchor coat layer is 1 μm or more and 5 μm or less, The gas barrier laminate, wherein the thickness of the layer containing the polyvinyl alcohol-based resin is 1 μm or more and 5 μm or less.

2. 2. The gas barrier laminate according to claim 1, wherein the first polyolefin having a polar group has at least one group selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

3. 3. The gas barrier laminate according to claim 1, wherein the second polyolefin having a polar group has at least one group selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

4. 2. The gas barrier laminate according to claim 1, wherein the first polyolefin having a polar group is a copolymer of an acrylic ester and maleic anhydride.

5. 2. The gas barrier laminate according to claim 1, wherein the first polyolefin having a polar group is an ethylene-vinyl acetate copolymer.

6. 2. The gas barrier laminate according to claim 1, wherein the first polyolefin having a polar group is an ethylene-glycidyl methacrylate copolymer.

7. 7. The gas barrier laminate according to claim 1, wherein the second polyolefin having a polar group is a copolymer of an acrylic ester and maleic anhydride.

8. 7. The gas barrier laminate according to claim 1, wherein the second polyolefin having a polar group is an ethylene-vinyl acetate copolymer.

9. 7. The gas barrier laminate according to claim 1, wherein the second polyolefin having a polar group is an ethylene-glycidyl methacrylate copolymer.

10. The gas barrier laminate according to any one of claims 1 to 9, wherein the vapor-deposited layer has a thickness of 30 nm or more and 100 nm or less.

11. 11. The gas barrier laminate according to claim 1, wherein the overcoat layer has a thickness of 2 μm or more and 10 μm or less.

12. 12. The gas barrier laminate according to claim 1, wherein the thickness of the paper base material is 30 μm or more and 100 μm or less, and the thickness of the paper base material accounts for 70% or more of the total thickness of the gas barrier laminate.

13. 13. The gas barrier laminate according to any one of claims 1 to 12, wherein the weight of the paper is 50 mass % or more based on the weight of the entire gas barrier laminate.

14. A gas barrier laminate described in any one of claims 1 to 13, wherein the overcoat layer is arranged so as to be in contact with the vapor deposition layer.

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

16. The packaging bag according to claim 15, having a folded portion.

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