Gas barrier laminate and packaging bag

Abstract

To provide a gas barrier laminate which has fold holding property that is a feature of paper and sufficient gas barrier property even after having been bent, and contributes to reduction in a used amount of a plastic material.SOLUTION: A gas barrier laminate has a paper base material, a vapor-deposited layer and a resin layer containing a polyolefin resin in this order, and is sealable by heat seal, wherein a basis weight of the paper base material is 30 to 100 g / m2, water vapor permeability at 40°C and 90%RH is 3 g / m2 / d or less, water vapor permeability at 40°C and 90%RH obtained by folding the gas barrier laminate with the paper base material outside, rotating a roller having a weight of 2 kg thereon once, and measuring it while the fold is opened is 4 g / m2 / d or less, and water vapor permeability at 40°C and 90%RH obtained by folding the gas barrier laminate with the paper base material inside, rotating a roller having a weight of 2 kg thereon once, and measuring it while the fold is opened is 4 g / m2 / d or less.SELECTED DRAWING: Figure 1

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 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 same. [Means for solving the problem]

[0008] The present invention provides a gas barrier laminate that is heat-sealable and includes a paper substrate and a vapor-deposited layer, wherein the paper substrate has a basis weight of 30 to 100 g / m. 2 and the water vapor permeability at 40°C and 90% RH is 3 g / m 2 The paper substrate was folded with the outermost layer, a 2 kg roller was rolled over it once, and the fold was opened and measured. The water vapor transmission rate at 40°C and 90% RH was 4 g / m or less. 2 The paper substrate was folded inward, a 2 kg roller was rolled over it once, and the fold was opened and measured. The water vapor transmission rate at 40°C and 90% RH was 4 g / m or less. 2 ·days or less, and the weight of the paper substrate is 47 mass% or more of the total amount of the gas barrier laminate.

[0009] The weight of the paper substrate may be 60% by mass or more based on the total weight of the gas barrier laminate.

[0010] The present invention also provides a gas barrier laminate that is heat-sealable and includes a paper substrate and a vapor-deposited layer, wherein the paper substrate has a basis weight of 30 to 100 g / m. 2 and the water vapor permeability at 40°C and 90% RH is 3 g / m 2 The paper substrate was folded with the outermost layer, a 2 kg roller was rolled over it once, and the fold was opened and measured. The water vapor transmission rate at 40°C and 90% RH was 4 g / m or less. 2 The paper substrate was folded inward, a 2 kg roller was rolled over it once, and the fold was opened and measured. The water vapor transmission rate at 40°C and 90% RH was 4 g / m or less. 2·days or less, and the thickness of the paper substrate is 60% or more of the thickness of the entire gas barrier laminate.

[0011] The thickness of the paper substrate may be 70% or more of the total thickness of the gas barrier laminate.

[0012] A layer containing 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 may be provided on the surface of the vapor-deposited layer opposite to the paper substrate.

[0013] The gas barrier laminate may comprise, in this order: a paper substrate; a layer containing 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; a vapor-deposited layer; and a layer containing 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.

[0014] The present invention also provides a packaging bag comprising the gas barrier laminate according to the present invention, the packaging bag having a heat seal strength of 3 N / 15 mm or more.

[0015] The packaging bag may have a folded portion. [Effects of the Invention]

[0016] 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]

[0017] [Figure 1] 1 is a schematic cross-sectional view of a gas barrier laminate according to one embodiment of the present invention. [Figure 2] 1 is a perspective view showing a package according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] <Gas barrier laminate> The gas barrier laminate according to this embodiment is a gas barrier laminate that includes a paper substrate and a vapor-deposited layer and can be sealed by heat sealing. As shown in Fig. 1, the gas barrier laminate 10 according to this embodiment may include at least a paper substrate 1, a vapor-deposited layer 2, and a polyolefin-containing layer 3. For example, a polyolefin-containing layer may be further provided between the paper substrate 1 and the vapor-deposited layer 2, and there may be two or more vapor-deposited layers, and there may also be two or more polyolefin-containing layers.

[0020] [Paper base material] The paper substrate is not particularly limited and may be appropriately selected depending on the intended use of the packaging material to which the gas barrier laminate is applied. Specific examples of the paper substrate include fine paper, special fine paper, coated paper, art paper, cast coated paper, construction paper, kraft paper, and glassine paper.

[0021] The paper base weight is 30 to 100 g / m 2 and 35 to 90 g / m 2 is preferable, and 40 to 80 g / m 2 The basis weight of the paper is more preferably 30 g / m 2 If the density is 100 g / m or more, the physical strength and processability as a packaging bag are good, which is preferable. 2 If the thickness is less than this, the flexibility and productivity of the packaging bag will be good, which is preferable.

[0022] The weight of the paper substrate is 47% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more or 80% by mass or more, based on the total weight of the gas barrier laminate. If the weight of the paper substrate is 47% by mass or more based on the total weight of the gas barrier laminate, the amount of plastic used can be sufficiently reduced, and if it is 50% by mass or more, the gas barrier laminate as a whole can be said to be made of paper and has excellent recyclability. There is no particular upper limit on the weight of the paper substrate, and it may, for example, be less than 100% by mass or 90% by mass or less.

[0023] The thickness of the paper substrate is preferably, for example, 60% or more, and more preferably 70% or more, of the total thickness of the gas barrier laminate. If the thickness of the paper substrate is 60% or more of the total thickness of the gas barrier laminate, the amount of plastic used can be sufficiently reduced, the gas barrier laminate as a whole can be said to be made of paper, and it has excellent recyclability. There is no particular upper limit on the thickness of the paper substrate, and it may be, for example, less than 100%, or 90% or less. The thickness of the paper substrate may, for example, be 30 μm or more and 100 μm or less, or 35 μm or more and 80 μm or less.

[0024] The paper substrate may have a coating layer at least on the side that comes into contact with the vapor-deposited layer described below. The coating layer serves to fill in the paper's irregularities, allowing the vapor-deposited layer to be formed uniformly and without defects. The coating layer may contain binder resins such as polyolefins, styrene-butadiene, styrene-acrylic, and ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, cellulose resins, and paraffin (wax), and fillers such as clay, kaolin, calcium carbonate, talc, and mica.

[0025] The thickness of the coating layer is not particularly limited, but may be, for example, 1 to 10 μm, or 3 to 8 μm.

[0026] <Vapour-deposited layer> The vapor-deposited layer has the role of imparting water vapor barrier properties to the gas barrier laminate, and is a layer obtained by vapor-depositing a metal or a metal oxide. The vapor-deposited layer may be obtained by vapor-depositing aluminum, and may be obtained by vapor-depositing aluminum oxide (AlO x ), silicon oxide (SiO x By providing a vapor deposition layer, the gas barrier properties of the gas barrier laminate can be improved, and the amount of plastic used in the gas barrier laminate can be reduced.

[0027] The thickness of the vapor-deposited layer may be appropriately set depending on the intended use, but may preferably be 10 nm or more, 30 nm or more, or 50 nm or more, and may be 500 nm or less, 100 nm or less, or 80 nm or less. A thickness of 10 nm or more makes it easy to ensure sufficient continuity of the vapor-deposited layer, and a thickness of 500 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.

[0028] From the viewpoint of gas barrier performance and film uniformity, it is preferable to form the vapor deposition layer by a vacuum film formation method. There are known methods for film formation, such as vacuum deposition, sputtering, and chemical vapor deposition (CVD), but vacuum deposition is preferred due to its high film formation rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because it allows for easy control of the film formation rate by adjusting the irradiation area and electron beam current, and allows for rapid heating and cooling of the deposition material.

[0029] When there are a plurality of vapor-deposited layers, the vapor-deposited layers may be made of the same material or different materials.

[0030] <Polyolefin-containing layer> The gas barrier laminate according to this embodiment may include a layer containing a polyolefin, preferably a layer containing at least one polyolefin selected from a carboxyl group, a carboxyl group salt, a carboxylic acid anhydride group, and a carboxylic acid ester, at least on the surface of the vapor-deposited layer opposite the paper substrate. The inclusion of such a polyolefin layer improves water vapor barrier properties due to the crystallinity of the polyolefin, and also improves adhesion to the vapor-deposited layer, prevents cracking of the vapor-deposited layer due to bending, and imparts heat-sealing properties to the gas barrier laminate. By combining such diverse functions, there is no need to provide a separate adhesive layer, protective layer, or heat-sealable resin layer, thereby reducing the amount of plastic used.

[0031] The polyolefin-containing layer is preferably a coating formed by applying and drying an aqueous emulsion, and preferably contains a polyolefin emulsion having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride, and a carboxylic ester.

[0032] When there are a plurality of layers containing polyolefin, the layers may be made of the same material or different materials.

[0033] The polyolefin-containing layer can be formed by applying a coating liquid containing the materials for forming the resin layer 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, 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, organic titanates, antiblocking agents, slip agents, and antifoaming agents.

[0034] The thickness of the polyolefin-containing layer may be, for example, 0.5 μm or more and 10 μm or less. A thickness of 0.5 μm or more makes it easier to obtain sufficient heat seal strength and barrier property improvement effects, while a thickness of 10 μm or less can reduce costs and increase the proportion of paper in the gas barrier laminate according to this embodiment.

[0035] <Water vapor permeability> 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 sufficiently low water vapor permeability.

[0036] The water vapor permeability of the gas barrier laminate according to this embodiment is 3 g / m when measured by the MOCON method under conditions of a temperature of 40°C and a relative humidity of 90% RH. 2 ·day or less is preferable, and 2 g / m 2 It is more preferable that the water vapor permeability is 3g / m or less. 2 By keeping the shelf life to 100 days or less, packaging bags using this gas barrier laminate can suppress deterioration of the contents due to moisture absorption and evaporation over a long period of time.

[0037] When the gas barrier laminate according to this embodiment is folded with the paper substrate facing outward, a 2 kg roller is rolled over it once, the fold is opened, and the water vapor permeability is measured, the water vapor permeability is 4 g / m under conditions of a temperature of 40°C and a relative humidity of 90% RH. 2 ·day or less is preferable, and 3g / m 2 It is more preferable that it is less than 1 day.

[0038] When the gas barrier laminate according to this embodiment is folded with the paper substrate facing inward, a 2 kg roller is rolled over it once, the fold is opened, and the water vapor permeability is measured, the water vapor permeability is 4 g / m under conditions of a temperature of 40°C and a relative humidity of 90% RH. 2 ·day or less is preferable, and 3g / m 2 It is more preferable that the water vapor permeability of the folded sheet is 4g / m or less.2 By keeping the shelf life to 100 days or less, deterioration due to moisture absorption and evaporation of the contents can be suppressed for a long period of time, even in the case of packaging bags with folds such as pillow packaging, three-sided seal packaging, and gusset packaging.

[0039] <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 is folded in a valley 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 when viewed from the innermost layer side.

[0040] The packaging bag may be formed into a bag shape by folding one gas barrier laminate in half so that the opposite sides of the paper base face each other, then folding it appropriately to the desired shape and heat sealing it, or may be formed into a bag shape by stacking two gas barrier laminates so that the opposite sides of the paper base face each other, and then heat sealing it.

[0041] In the packaging bag according to this embodiment, the heat seal strength may be 3 N / 15 mm or more, or 4 N / 15 mm or more. The upper limit of the heat seal strength is not particularly limited, but may be, for example, 10 N / 15 mm or less. If the heat seal strength is 3 N / 15 mm or more, the contents can be protected throughout the various distribution processes until the packaging bag is opened.

[0042] The packaging bag can contain food, medicine, and other contents. 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. Furthermore, since the packaging bag contains a high proportion of paper, it can potentially be recycled as recycled paper after use, reducing the amount of plastic waste disposed of.

[0043] 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]

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0045] <Preparation of gas barrier laminate> Examples 1 to 9 A first resin layer, a first vapor-deposited layer, a second resin layer, a second vapor-deposited layer, and a third resin layer were formed in this order on the clay-coated surface of a paper substrate to produce a gas barrier laminate having the configuration shown in Tables 1 and 2 below. The first resin layer, the second resin layer, and the third resin layer were formed by applying a coating liquid with a bar coater and drying in an oven, and the first vapor-deposited layer and the second vapor-deposited layer were formed by vacuum deposition. The materials used are as follows: Clay coated paper: Paper (paper base material) thickness: 50 μm, Paper density: 0.8 g / cm 3 , Clay coat layer thickness: 5 μm, Clay coat layer density: 3 g / cm 3 ,Basic weight:60g / m 2 (Paper:43.6g / m 2 , Clay coat layer: 16.4g / m 2 ) Chemipearl S100: Aqueous dispersion of polyolefin containing carboxyl salt (Mitsui Chemicals) Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salt (manufactured by Mitsui Chemicals) Chemipearl V300: Vinyl acetate polyolefin aqueous dispersion (Mitsui Chemicals) Urethane-curing acrylic resin In the table, the "weight ratio of the paper substrate" is a value based on the total weight of the gas barrier laminate, and the "thickness ratio of the paper substrate" is a value based on the entire thickness of the gas barrier laminate.

[0046] (Examples 10 to 18) A polyolefin-containing layer, a vapor-deposited layer, and a polyolefin-containing layer were formed in this order on the clay-coated surface of a paper substrate to produce gas barrier laminates with the structures shown in Tables 3 and 4 below. The polyolefin-containing layer was formed by applying a coating liquid with a bar coater and drying in an oven, and the vapor-deposited layer was formed by vacuum deposition. The materials used are as follows: Clay coated paper: Paper thickness: 50 μm, Paper density: 0.8 g / cm 3 , Clay coat layer thickness: 5 μm, Clay coat layer density: 3 g / cm 3 ,Basic weight:60g / m 2 (Paper:43.6g / m 2 , Clay coat layer: 16.4g / m 2 ) Clay coated paper: Paper thickness: 30 μm, Paper density: 0.8 g / cm 3 , Clay coat layer thickness: 5 μm, Clay coat layer density: 3 g / cm 3 , Basis weight: 40g / m 2 (Paper:24.6g / m 2 , Clay coat layer: 15.4g / m 2 ) Clay coated paper: Paper thickness: 100μm, Paper density: 0.8g / cm 3 , Clay coat layer thickness: 5 μm, Clay coat layer density: 3 g / cm 3 , Basis weight: 100g / m 2 (Paper:84.2g / m 2 , Clay coat layer: 15.8g / m 2 ) Chemipearl S100: Aqueous dispersion of polyolefin containing carboxyl salt (Mitsui Chemicals) Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salt (manufactured by Mitsui Chemicals) Chemipearl V300: Vinyl acetate polyolefin aqueous dispersion (Mitsui Chemicals)

[0047] (Comparative Examples 1 to 4) A resin layer, a vapor-deposited layer, and a polyolefin-containing layer were formed in this order on the clay-coated surface of a paper substrate to produce a gas barrier laminate with the configuration shown in Table 5 below. The resin layer and the polyolefin-containing layer were formed by applying a coating liquid with a bar coater and drying in an oven, and the vapor-deposited layer was formed by vacuum deposition. The materials used are as follows: Clay coated paper: Paper thickness: 50 μm, Paper density: 0.8 g / cm 3 , Clay coat layer thickness: 5 μm, Clay coat layer density: 3 g / cm 3 ,Basic weight:60g / m 2 (Paper:43.6g / m 2 , Clay coat layer: 16.4g / m 2 ) Chemipearl S100: Aqueous dispersion of polyolefin containing carboxyl salt (Mitsui Chemicals) Chemipearl V300: Vinyl acetate polyolefin aqueous dispersion (Mitsui Chemicals) Urethane-curing acrylic resin

[0048] (Comparative Example 5) A coating solution containing an amide 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 amide 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 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 polyolefin, resulting in a gas barrier laminate. The thickness of the polyolefin layer was 3 μm.

[0049] (Comparative Example 6) A coating solution consisting of a 1:1 solids ratio mixture of an aqueous dispersion of kaolin (Imerys Barrisurf HX) and a styrene-acrylic copolymer emulsion (Siden Chemical X-511-374E) was applied to the surface of paper (clay-coated paper, paper thickness: 50 μm, clay coating thickness: 5 μm) using a bar coater and dried in an oven to form a water vapor barrier resin layer. The layer thickness was 15 μm. Next, an aqueous solution of polyvinyl alcohol (Kuraray PVA117) was applied to this layer using a bar coater and dried in an oven to form a gas barrier layer. The layer thickness was 5 μm. A 30 μm thick layer of low-density polyethylene (Japan Polyethylene LC602A) was then extrusion laminated to form a gas barrier laminate.

[0050] (Comparative Example 7) A low-density polyethylene (LC602A manufactured by Japan Polyethylene Co., Ltd.) was laminated to a thickness of 30 μm on a silica-deposited PET film (GL film manufactured by Toppan Printing Co., Ltd., thickness 12 μm) via a polyurethane-based anchor coating agent by extrusion lamination. A polyurethane-based two-component curing adhesive was applied to the silica-deposited PET film side of this laminated film at a dry weight of 5 g / m. 2 The coating was then dry-laminated to paper (clay-coated paper, paper thickness: 50 μm, clay coating layer thickness: 5 μm) to obtain a gas barrier laminate.

[0051] <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 2 kg roller was used to make a crease in the gas barrier laminate while rotating it once at a speed of 300 mm / min, and the water vapor permeability of the gas barrier laminate after opening was also measured in the same manner. In Tables 1 to 5, "valley fold" refers to the gas barrier laminate after the gas barrier laminate has been valley-folded as viewed from the paper substrate side, and "mountain fold" refers to the gas barrier laminate after the gas barrier laminate has been mountain-folded as viewed from the paper substrate side. Tables 1 to 6 show the results in units of [g / m 2 ·day].

[0052] <Heat seal strength measurement> Two gas barrier laminates were stacked with the paper substrate facing outward 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 speed of 300 mm / min. The results are shown in Tables 1 to 6 in units of N / 15 mm.

[0053] <Performance evaluation as a gas barrier packaging bag> The gas barrier laminate was cut into a size of 8 cm x 18 cm, and a gusset packaging bag was made. 15 g of calcium chloride was filled into the bag, and the weight of the sealed packaging bag was measured. The bag was then stored for one month at a temperature of 40°C and a relative humidity of 90%. The weight change thereafter was measured, and a weight increase of 2 g or less was marked "Good," and a weight increase of more than 2 g was marked "Poor." The results are shown in Tables 1 to 6.

[0054] <Recycled paper recyclability evaluation> 150 g of the gas barrier laminate was weighed out and subjected to a disintegration treatment in alkaline water. After removing the plastic components, the laminate was washed with water and the dry weight of the recovered pulp fiber was measured. Those from which 70 g or more of pulp fiber was recovered were judged to be recyclable and given a "Good" rating, while those from which less than 50 g of pulp fiber was recovered were judged to be unrecyclable and given a "Poor" rating. These results are shown in Tables 1 to 6.

[0055] [Table 1]

[0056] [Table 2]

[0057] [Table 3]

[0058] [Table 4]

[0059] [Table 5]

[0060] [Table 6] [Explanation of symbols]

[0061] 1...paper substrate, 2...vapor-deposited layer, 3...polyolefin-containing layer, 10...gas barrier laminate, 20...gusset bag, B1, B2...folded portions

Claims

1. A gas barrier laminate that can be sealed by heat sealing, a paper substrate having a coating layer made of a polyvinyl alcohol-based resin on its surface; a vapor deposition layer provided on the surface of the coating layer of the paper substrate; a resin layer containing a polyolefin resin; in this order, The paper base has a basis weight of 30 to 100 g / m ２ and Water vapor permeability at 40°C and 90% RH is 3g / m ２ ・day or less, The paper substrate was folded with the outside facing outward, and a 2 kg roller was rolled over it once. The fold was opened and measured. The water vapor permeability at 40°C and 90% RH was 4 g / m ２ The paper substrate is folded with the inside facing inward, a 2 kg roller is rolled over it once, the fold is opened, and the water vapor transmission rate at 40°C and 90% RH is measured at 4 g / m or less. ２ ・day or less, the weight of the paper substrate is 47% by mass or more based on the total amount of the gas barrier laminate; the resin layer has a first surface and a second surface, the first surface facing the vapor deposition layer, and the second surface constituting a surface of the gas barrier laminate; The gas barrier laminate comprises the polyolefin resin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

2. The gas barrier laminate according to claim 1 , wherein the weight of the paper substrate is 60% by mass or more based on the total amount of the gas barrier laminate.

3. A gas barrier laminate that can be sealed by heat sealing, a paper substrate having a coating layer made of a polyvinyl alcohol-based resin on its surface; a vapor deposition layer provided on the surface of the coating layer of the paper substrate; a resin layer containing a polyolefin resin; in this order, The paper base has a basis weight of 30 to 100 g / m ２ and Water vapor permeability at 40°C and 90% RH is 3g / m ２ ・day or less, The paper substrate was folded with the outside facing outward, and a 2 kg roller was rolled over it once. The fold was opened and measured. The water vapor permeability at 40°C and 90% RH was 4 g / m ２ The paper substrate is folded with the inside facing inward, a 2 kg roller is rolled over it once, the fold is opened, and the water vapor transmission rate at 40°C and 90% RH is measured at 4 g / m or less. ２ ・day or less, the thickness of the paper substrate is 60% or more of the total thickness of the gas barrier laminate; the resin layer has a first surface and a second surface, the first surface facing the vapor deposition layer, and the second surface constituting a surface of the gas barrier laminate; The gas barrier laminate comprises the polyolefin resin having at least one selected from a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic acid ester.

4. The gas barrier laminate according to claim 3 , wherein the thickness of the paper substrate is 70% or more of the total thickness of the gas barrier laminate.

5. A packaging bag comprising the gas barrier laminate according to any one of claims 1 to 4, wherein the packaging bag has a heat seal strength of 3 N / 15 mm or more.

6. The packaging bag according to claim 5, which has a folded portion.

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