Gas barrier laminate and packaging bag

Abstract

A layered gas-barrier product which comprises, in the following order, a paper base, a layer comprising a poly(vinyl alcohol)-based resin, a vapor deposition layer, and a layer comprising a polyolefin having polar groups.

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, a layer containing a polyvinyl alcohol-based resin, a vapor-deposited layer, and a layer containing a polyolefin having a polar group.

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

[0010] The polyolefin having a polar group may be a copolymer of an acrylic acid ester and maleic anhydride.

[0011] The polyolefin having a polar group may be an ethylene-vinyl acetate copolymer.

[0012] The polyolefin having a polar group may be an ethylene-glycidyl methacrylate copolymer.

[0013] The thickness of the layer containing the polyvinyl alcohol resin may be 1 μm or more and 5 μm or less.

[0014] The thickness of the deposited layer may be 30 nm or more and 100 nm or less.

[0015] The thickness of the layer containing the polyolefin having a polar group may be 2 μm or more and 10 μm or less.

[0016] 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.

[0017] The weight of the paper may be 50% by mass or more based on the weight of the entire gas barrier laminate.

[0018] The present invention also provides a packaging bag comprising the gas barrier laminate according to the present invention.

[0019] The packaging bag may have a folded portion. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a gas barrier laminate that has the fold retention properties that are 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. [Brief explanation of the drawings]

[0021] [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

[0022] 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.

[0023] <Gas barrier laminate> 1 is a schematic cross-sectional view showing a gas barrier laminate according to one embodiment. The gas barrier laminate 10 according to one embodiment comprises, in this order, a paper substrate 1, a layer 2 containing a polyvinyl alcohol resin, a vapor-deposited layer 3, and a layer 4 containing a polyolefin having a polar group.

[0024] [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.

[0025] The paper substrate 1 may have a coating layer at least on the side that contacts the layer 2 containing a polyvinyl alcohol-based resin, which will be described later. The coating layer prevents the layer 2 containing a polyvinyl alcohol-based resin from seeping into the paper and also serves as a sealant, filling in any irregularities in the paper, allowing the layer containing a polyvinyl alcohol-based resin to be formed uniformly and without defects. The coating layer may contain binder resins such as styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate copolymers, polyvinyl alcohol-based resins, cellulose-based resins, paraffin (wax), and the like, and fillers such as clay, kaolin, calcium carbonate, talc, and mica.

[0026] The thickness of the coating layer is not particularly limited, but may be, for example, 1 to 10 μm, or 3 to 8 μm.

[0027] 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.

[0028] [Layer containing polyvinyl alcohol-based resin] The layer 2 containing a polyvinyl alcohol-based resin is provided on the surface of the paper substrate to improve adhesion between the paper substrate 1 and the vapor-deposited layer 3 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 1700 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 1700 or less, the viscosity of the coating liquid of the polyvinyl alcohol-based resin described below will be low, improving coatability.

[0029] The polyvinyl alcohol-based resin-containing layer 2 can be provided by applying a coating liquid containing the above-mentioned polyvinyl alcohol-based 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. Mixtures of water and alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol are particularly preferred. The coating liquid may also contain additives such as surfactants, preservatives, storage stabilizers, silane coupling agents, and organic titanates.

[0030] Such a layer 2 containing a polyvinyl alcohol-based resin has excellent flexibility, and can suppress cracking of the vapor-deposited layer described below after bending (folding), thereby suppressing deterioration of the gas barrier properties, and can also improve adhesion between the vapor-deposited layer and the layer containing a polyvinyl alcohol-based resin.

[0031] The thickness of the layer 2 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 unevenness of the paper substrate described above can be efficiently filled, allowing the vapor deposition layer described below to be laminated uniformly. Furthermore, if the thickness is 5 μm or less, the vapor deposition layer can be laminated uniformly while keeping costs down.

[0032] [Vapour-deposited layer] The vapor-deposited layer 3 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.

[0033] The thickness of the vapor-deposited layer 3 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 of the vapor-deposited layer 3 makes it easy to ensure sufficient continuity of the vapor-deposited layer 3, 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.

[0034] The deposition layer 3 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 fast 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.

[0035] [Layer containing polyolefin having polar groups] Layer 4 containing polyolefin having polar groups is provided on the surface of vapor-deposited layer 3 so as to be in contact with vapor-deposited layer 3, and contains polyolefin having polar groups. By using polyolefin having polar groups, the crystallinity of the polyolefin improves the water vapor barrier properties, and the flexibility of the polyolefin improves the flex resistance. Furthermore, the introduction of polar groups improves adhesion to the vapor-deposited layer, and the resulting coating is an aqueous coating in which the polyolefin is dispersed in water, which is environmentally friendly.

[0036] The polyolefin containing a polar group may include a polyolefin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

[0037] As the polyolefin having a polar group, 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) or an unsaturated carboxylic acid ester, or a salt of a carboxylic acid neutralized with a basic compound may be used, or 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 also be used.

[0038] Specific examples of polyolefins having a polar group include copolymers of acrylic acid ester and maleic anhydride, ethylene-vinyl acetate copolymers, and ethylene-glycidyl methacrylate copolymers.

[0039] The layer 4 containing such a polyolefin having a polar group 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 above-mentioned polyolefin, a gas barrier laminate with excellent water vapor barrier properties can be obtained. Furthermore, by providing a layer containing the above-mentioned polyolefin having a polar group, it can also function as a heat-sealing layer, so there is no need to provide a separate heat-sealing layer.

[0040] The layer 4 containing the polyolefin having a polar group may contain other components in addition to the polyolefin, such as a silane coupling agent, an organic titanate, polyacrylic, polyester, polyurethane, polycarbonate, polyurea, polyamide, a polyolefin emulsion, polyimide, melamine, and phenol.

[0041] The content of the polyolefin in the layer 4 containing the polyolefin having a polar group may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0042] The thickness of the layer 4 containing polyolefin having a polar group 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. When the thickness of the layer 4 containing polyolefin having a polar group is 2 μm or more, it can fully function as the heat seal layer described above. Furthermore, when the thickness of the layer 4 containing polyolefin having a polar group is 10 μm or less, it can fully exhibit adhesion to the vapor deposition layer and barrier properties while suppressing costs.

[0043] The layer 4 containing a polyolefin having a polar group can be formed by applying a coating liquid containing the above-mentioned polyolefin and a solvent onto 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.

[0044] The gas barrier laminate according to this embodiment can exhibit sufficient gas barrier properties even after being folded. In this specification, gas barrier properties refer to a state in which the water vapor permeability and oxygen permeability are sufficiently low.

[0045] The gas barrier laminate according to this embodiment has a water vapor permeability of 3 g / m at 40°C and 90% RH when it is folded with the paper substrate facing outward, rolled once with a 600 g roller, and then opened and measured. 2 / d or less, and the oxygen permeability at 30℃ 70%RH is 3cc / 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℃ 70%RH is 3cc / m 2 It is preferable that the temperature is / d / atm or less.

[0046] <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.

[0047] The packaging bag may be formed into a bag shape by folding one gas barrier laminate in half so that the layers 4 containing the polyolefin having a polar group face each other, and then folding it appropriately into a desired shape and heat sealing it, or may be formed into a bag shape by stacking two gas barrier laminates so that the layers 4 containing the polyolefin having a polar group face each other, and then heat sealing it.

[0048] 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.

[0049] Here, the heat seal strength was measured by stacking two gas barrier laminates 10 with the layers 4 containing polyolefin having polar groups 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 the laminate, and measuring the maximum load when T-peeling at a peel speed of 300 mm / min.

[0050] 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.

[0051] 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]

[0052] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0053] <Preparation of gas barrier laminate> Example 1 A coating solution 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 in an 8:2 water / IPA mixture was applied to the clay-coated surface of paper (clay-coated paper, paper thickness: 50 μm, clay-coated layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing polyvinyl alcohol resin. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited onto the polyvinyl alcohol resin-containing layer using a vacuum vapor deposition method. The aluminum vapor-deposited layer was 50 nm thick. 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 a layer containing polyolefin with polar groups, thereby obtaining a gas barrier laminate. The thickness of the layer containing polyolefin with polar groups was 3 μm. The weight of paper in the gas barrier laminate was 82% by mass.

[0054] Example 2 Except for changing the thickness of the layer containing the polyvinyl alcohol resin to 1 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 85 mass %.

[0055] Example 3 Except for changing the thickness of the layer containing the polyvinyl alcohol resin 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 79 mass %.

[0056] 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 82 mass %.

[0057] 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 82 mass %.

[0058] Example 6 Except for changing the thickness of the layer containing the polyolefin having a polar group 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 83 mass %.

[0059] Example 7 Except for changing the thickness of the layer containing the polyolefin having a polar group 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 73 mass %.

[0060] Example 8 A gas barrier laminate was obtained in the same manner as in Example 1, except that the clay-coated paper used had a paper thickness of 30 μm and a clay coating layer thickness of 5 μm. The weight of the paper in the gas barrier laminate was 73 mass %.

[0061] Example 9 A gas barrier laminate was obtained in the same manner as in Example 1, except that the clay-coated paper used had a paper thickness of 100 μm and a clay coating layer thickness of 5 μm. The weight of the paper in the gas barrier laminate was 90 mass %.

[0062] 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 %.

[0063] 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 82 mass %.

[0064] Example 12 A gas barrier laminate was obtained in the same manner as in Example 1, except that a polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 1000 was used as the polyvinyl alcohol resin.

[0065] Example 13 A gas barrier laminate was obtained in the same manner as in Example 1, except that the polyvinyl alcohol resin used in Example 1 was changed to a modified polyvinyl alcohol resin (product name: Exeval AQ4104, manufactured by Kuraray Co., Ltd.).

[0066] Example 14 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid containing an ethylene-vinyl acetate copolymer resin (product name: Chemipearl V300, manufactured by Mitsui Chemicals) was applied using a bar coater and dried in an oven to form a layer containing a polyolefin having a polar group.

[0067] Example 15 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid containing a polyolefin resin containing a carboxyl group, a salt of a carboxyl group, a carboxylic acid anhydride, and a carboxylic acid ester (trade name: Bondine HX-8290, manufactured by Arkema) was applied with a bar coater and dried in an oven to prepare a coating layer made of polyolefin. The coating liquid containing the polyolefin resin was prepared as follows. A polyolefin resin consisting of ethylene, ethyl acrylate, and maleic anhydride (trade name: Bondine HX-8290, manufactured by Arkema) was mixed with isopropanol, triethylamine, and distilled water in a mass ratio of 20 / 20 / 1 / 59, and the mixture was heated and stirred to prepare an aqueous dispersion of the polyolefin resin.

[0068] 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 produce a coating solution layer containing a polyolefin resin.

[0069] Example 17 A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the clay-coated surface of paper (clay-coated paper, paper thickness: 50 μm, clay-coated layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing a polyolefin having polar groups. The layer thickness was 3 μm. Next, a coating solution prepared by dissolving polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 500 in a water / IPA solution at a solids concentration of 10% by mass was applied to the layer containing the polar groups using a bar coater and dried in an oven to form a layer containing polyvinyl alcohol resin. The layer thickness was 1 μm. Next, aluminum was vapor-deposited onto the layer containing polyvinyl alcohol resin by vacuum deposition. The thickness of the aluminum-deposited 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 a layer containing a polyolefin having a polar group, yielding a gas barrier laminate. The thickness of the layer containing a polyolefin having a polar group was 3 μm. The weight of paper in the gas barrier laminate was 81% by mass.

[0070] Example 18 A coating solution containing a carboxyl group salt (product name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied to the clay-coated surface of paper (clay-coated paper, paper thickness: 50 μm, clay-coated layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing a polyolefin having polar groups. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited onto the layer containing the polyolefin having polar groups using a vacuum vapor deposition method. The thickness of the aluminum vapor-deposited layer was 50 nm. A coating solution prepared by dissolving polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 500 in a water / IPA solution at a solids concentration of 10% by mass was then applied onto the vapor-deposited layer using a bar coater and dried in an oven to form a layer containing polyvinyl alcohol resin. The thickness of the layer was 3 μm. Subsequently, aluminum was vapor-deposited onto the layer containing the polyvinyl alcohol resin using a vacuum vapor deposition method. The thickness of the aluminum vapor-deposited 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 a layer containing a polyolefin having a polar group, thereby obtaining a gas barrier laminate. The thickness of the layer containing a polyolefin having a polar group was 3 μm. The weight of paper in the gas barrier laminate was 78% by mass.

[0071] Example 19 A coating solution containing a polyolefin resin containing carboxyl groups, carboxyl group salts, carboxylic anhydride groups, and carboxylic acid esters (see Example 15 for the preparation of the coating solution) was applied to the clay-coated surface of paper (clay-coated paper, paper thickness: 50 μm, clay-coated layer thickness: 5 μm) using a bar coater and dried in an oven to form a layer containing polyolefin having polar groups. The layer thickness was 2 μm. Next, a coating solution prepared by dissolving polyvinyl alcohol resin with a saponification degree of 98% and a polymerization degree of 500 in a water / IPA solution at a solids concentration of 10% by mass was applied to the layer containing polyolefin having polar groups using a bar coater and dried in an oven to form a layer containing polyvinyl alcohol resin. The layer thickness was 1 μm. Next, aluminum was vapor-deposited on the layer containing polyvinyl alcohol resin by vacuum deposition. The aluminum vapor-deposited layer thickness 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 a layer containing a polyolefin having a polar group, yielding a gas barrier laminate. The thickness of the layer containing a polyolefin having a polar group was 3 μm. The weight of paper in the gas barrier laminate was 82% by mass.

[0072] Example 20 A gas barrier laminate was obtained in the same manner as in Example 19, except that the polyvinyl alcohol resin was changed to a modified polyvinyl alcohol resin (trade name: Exeval AQ4104, manufactured by Kuraray Co., Ltd.).

[0073] (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 82 mass %.

[0074] (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 a 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 a polyvinyl alcohol resin and TEOS. The layer thickness was 0.4 μm. A coating 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 a polyolefin having a polar group, thereby obtaining a gas barrier laminate. The thickness of the layer containing a polyolefin having a polar group was 3 μm. The weight of paper in the gas barrier laminate was 80% by mass.

[0075] (Comparative Example 3) A coating solution containing a carboxyl group salt (product name: Chemipearl S100, 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 a layer containing a polyolefin having polar groups. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited on the layer containing the polyolefin having polar groups. 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 a layer containing a polyolefin having polar groups, thereby obtaining a gas barrier laminate. The thickness of the layer containing the polyolefin having polar groups was 3 μm. The weight of paper in the gas barrier laminate was 82% by mass.

[0076] Comparative Example 4 A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid containing an ethylene-vinyl acetate copolymer resin (product name: Chemipearl V300, manufactured by Mitsui Chemicals) was used instead of the coating liquid containing a polyvinyl alcohol resin. The weight of paper in the gas barrier laminate was 82 mass %.

[0077] (Comparative Example 5) A gas barrier laminate was obtained in the same manner as in Example 1, except that a coating liquid containing a urethane-curing acrylic resin was used instead of the coating liquid containing a polyvinyl alcohol resin. The weight of paper in the gas barrier laminate was 82 mass %.

[0078] (Comparative Example 6) A coating solution containing a carboxyl group salt (product name: Chemipearl S100, 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 a layer containing a polyolefin having polar groups. The layer thickness was 3 μm. Subsequently, aluminum was vapor-deposited on the layer containing a polyolefin having polar groups. 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 coating 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 a polyolefin having polar groups, thereby obtaining a gas barrier laminate. The thickness of the layer containing a polyolefin having polar groups was 3 μm. The weight of paper in the gas barrier laminate was 81% by mass.

[0079] (Comparative Example 7) A gas barrier laminate was obtained in the same manner as in Comparative Example 6, except that instead of applying a coating liquid containing a polyvinyl alcohol resin with a bar coater and drying in an oven to form a layer containing a polyvinyl alcohol resin, a coating liquid containing a polyvinyl alcohol resin and TEOS was applied with a bar coater and dried in an oven to form a layer containing a polyvinyl alcohol resin and TEOS. The thickness of this layer was 1 μm.

[0080] <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 8, "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 8 show the results in units of [g / m 2 ·day].

[0081] <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 made by MOCON at a temperature of 30°C and a relative humidity of 70%. The results are shown in Tables 1 to 8 in units of [cc / m 2 / d / atm].

[0082] <Heat seal strength measurement> Two gas barrier laminates were stacked with the polar group-containing polyolefin 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 when T-peeled at a peel rate of 300 mm / min was measured. The results are shown in Tables 1 to 8 in units of N / 15 mm.

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

[0086] [Table 4]

[0087] [Table 5]

[0088] [Table 6]

[0089] [Table 7]

[0090] [Table 8] [Explanation of symbols]

[0091] 1...paper substrate, 2...layer containing polyvinyl alcohol-based resin, 3...vapor-deposited layer, 4...layer containing polyolefin having a polar group, 10...gas barrier laminate, 20...gusset bag, B1, B2...folded portion

Claims

1. A gas barrier laminate used in the manufacture of a packaging bag for containing contents, comprising: A paper substrate; a layer containing a polyvinyl alcohol-based resin; a deposition layer; a layer containing a polyolefin having a polar group; are provided in this order from the outside to the inside, The gas barrier laminate is manufactured into a bag so that the layer containing the polyolefin having a polar group constitutes the innermost layer of the gas barrier laminate, and the layer containing the polyolefin having a polar group constitutes the inner surface of the packaging bag.

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

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

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

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

6. 6. The gas barrier laminate according to claim 1, wherein the layer containing the polyvinyl alcohol-based resin has a thickness of 1 μm or more and 5 μm or less.

7. The gas barrier laminate according to any one of claims 1 to 6, wherein the vapor-deposited layer has a thickness of 30 nm or more and 100 nm or less.

8. 8. The gas barrier laminate according to claim 1, wherein the layer containing the polyolefin having a polar group has a thickness of 2 μm or more and 10 μm or less.

9. 9. 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.

10. 10. The gas barrier laminate according to claim 1, wherein the weight of the paper is 50% by mass or more based on the weight of the entire gas barrier laminate.

11. A gas barrier laminate described in any one of claims 1 to 10, wherein a layer containing the polyolefin having the polar group is provided so as to be in contact with the vapor deposition layer.

12. A packaging bag used to store contents, comprising the gas barrier laminate according to any one of claims 1 to 11, A packaging bag, wherein the layers of the gas barrier laminate containing the polyolefin having a polar group are stacked so as to face each other and heat-sealed to form a bag shape, and the layer containing the polyolefin having a polar group forms the inner surface of the packaging bag.

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