Gas barrier laminate and packaging bag

Abstract

To provide a gas barrier laminate having fold holding properties being the characteristics of paper, having sufficient gas barrier properties even after folded and contributing to the reduction of the use amount of a plastic material.SOLUTION: A gas barrier laminate comprising a paper substrate and a vapor deposition layer, the gas barrier laminate being sealable by heat sealing, wherein the paper substrate has a basis weight of 30 to 100g / m2, the gas barrier laminate has a water vapor transmission rate and an oxygen transmission rate each in a specific range, the weight of the paper substrate is 47% by mass or more based on the total amount of the gas barrier laminate, and the gas barrier laminate comprises a polyvinyl alcohol resin-containing layer between the paper substrate and the vapor deposition layer.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 gas barrier laminate. [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, the paper substrate having 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 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 2cc / m 2 The paper substrate is folded with the outside facing out, a 2 kg roller is rolled over it once, and the fold is opened and measured. The water vapor transmission rate at 40°C and 90% RH is 4 g / m or less. 2 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 The paper substrate is folded 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 4 g / m or less. 2 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 / d / atm 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 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 2cc / m 2The paper substrate is folded with the outside facing out, a 2 kg roller is rolled over it once, and the fold is opened and measured. The water vapor transmission rate at 40°C and 90% RH is 4 g / m or less. 2 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 The paper substrate is folded 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 4 g / m or less. 2 ·day or less, and the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 / d / atm 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] A layer containing a polyvinyl alcohol-based resin may be provided between the paper substrate and the vapor-deposited layer.

[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 layer 2 containing a polyvinyl alcohol-based resin, a vapor-deposited layer 3, and a layer 4 containing a polyolefin. For example, a layer containing a polyolefin may be further included between the paper substrate and the vapor-deposited layer. Furthermore, there may be two or more vapor-deposited layers, and there may also be two or more layers containing a polyolefin and two or more layers containing a polyvinyl alcohol-based resin.

[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. 2If 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] <Layer Containing Polyvinyl Alcohol Resin> The layer containing a polyvinyl alcohol-based resin is provided, for example, on the surface of a paper substrate to improve adhesion between the paper substrate and the vapor-deposited layer 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 the coating liquid of the polyvinyl alcohol-based resin described below will be low, improving coatability.

[0031] A method for providing a layer containing a polyvinyl alcohol-based resin can be, for example, to apply a coating liquid containing the above-mentioned polyvinyl alcohol-based resin and a solvent to a paper substrate and dry 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. In particular, a mixed solvent of water and an alcohol such as methyl alcohol, ethyl alcohol, or isopropyl alcohol is preferred. The coating liquid may also contain additives such as surfactants, preservatives, storage stabilizers, silane coupling agents, organic titanates, polyolefin emulsions, and antifoaming agents.

[0032] Such a layer containing a polyvinyl alcohol-based resin has excellent flexibility, and can suppress cracking of the vapor-deposited layer 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.

[0033] The thickness of the layer containing the polyvinyl alcohol 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, and the vapor-deposited layer can be laminated uniformly. Furthermore, if the thickness is 5 μm or less, the vapor-deposited layer can be laminated uniformly while suppressing costs.

[0034] <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.

[0035] 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.

[0036] When there are a plurality of layers containing polyolefin, the layers may be made of the same material or different materials.

[0037] 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 titanate antiblocking agents, slip agents, and antifoaming agents.

[0038] 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.

[0039] 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.

[0040] <Water vapor permeability> 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 3 g / 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.

[0041] 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.

[0042] 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.

[0043] <Oxygen permeability> The oxygen permeability of the gas barrier laminate according to this embodiment is 2 cc / m when measured according to JIS K7126, Method B (isobaric method) under conditions of a temperature of 30°C and a relative humidity of 70% RH. 2 / d / atm or less is preferable, and 1cc / m 2 It is more preferable that the oxygen permeability is 2 cc / m 2 By keeping the gas barrier laminate at 1000 kJ / d / atm or less, the packaging bag using the gas barrier laminate can suppress deterioration of the contents due to oxidation for a long period of time.

[0044] The gas barrier laminate according to this embodiment has an oxygen permeability of 5 cc / m at 30°C and 70% RH when it is folded with the paper substrate facing outward, rolled once over a 2 kg roller, and then opened and measured. 2 / d / atm or less is preferable, and 3cc / m 2 It is more preferable that it is / d / atm or less.

[0045] The gas barrier laminate according to this embodiment has an oxygen permeability of 5 cc / m at 30°C and 70% RH when it is folded with the paper substrate on the inside, rolled over with a 2 kg roller once, and then opened and measured. 2 / d / atm or less is preferable, and 3cc / m 2 It is more preferable that the oxygen permeability of the folded sheet is 5cc / m 2 By keeping the temperature at or below / d / atm, deterioration of the contents due to oxidation can be suppressed for a long period of time, even in packaging bags with folds such as pillow packaging, three-sided seal packaging, and gusset packaging.

[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 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0052] <Preparation of gas barrier laminate> (Examples 1 to 12, Comparative Example 1) A layer containing a polyvinyl alcohol-based resin, a vapor-deposited layer, and a layer containing a polyolefin 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 1 to 4 below. The layer containing a polyvinyl alcohol-based resin and the layer containing a polyolefin 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 ) 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 ) Polyvinyl alcohol: saponification degree 98%, polymerization degree 500 (Kuraray) Modified polyvinyl alcohol: Exeval RS-4104 (Kuraray) Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salt (manufactured by Mitsui Chemicals) 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.

[0053] (Examples 13 to 24, Comparative Examples 2 to 3) A polyolefin-containing layer, a polyvinyl alcohol-based resin-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 5 to 8 below. The polyvinyl alcohol-based resin-containing 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 ) 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 ) Polyvinyl alcohol: saponification degree 98%, polymerization degree 500 (Kuraray) Modified polyvinyl alcohol: Exeval RS-4104 (Kuraray) Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salt (manufactured by Mitsui Chemicals)

[0054] Examples 25 to 32 A polyolefin-containing layer, a vapor-deposited layer, a polyvinyl alcohol-based resin-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 9 and 10 below. The polyvinyl alcohol-based resin-containing 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 ) Polyvinyl alcohol: saponification degree 98%, polymerization degree 500 (Kuraray) Modified polyvinyl alcohol: Exeval RS-4104 (Kuraray) 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)

[0055] Comparative Example 4 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.

[0056] (Comparative Example 5) 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.

[0057] (Comparative Example 6) 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.

[0058] <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 11, "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 11 show the results in units of [g / m 2 ·day].

[0059] <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 MOCON, at a temperature of 30°C and a relative humidity of 70%. The results are shown in Tables 1 to 11 in units of [cc / m 2 / d / atm].

[0060] <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 11 in units of N / 15 mm.

[0061] <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. Baked confectionery (cookies) was filled into the sealed packaging bag, and the bag was stored for one month in an environment of 40°C temperature and 90% relative humidity. The contents were then removed and the appearance and taste were checked. Those that showed no change before and after storage were marked with "Good", and those that showed a clear change were marked with "Poor". The results are shown in Tables 1 to 11.

[0062] <Recycled paper recyclability evaluation> 150 g of the gas barrier laminate was weighed 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 11.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] [Table 4]

[0067] [Table 5]

[0068] [Table 6]

[0069] [Table 7]

[0070] [Table 8]

[0071] [Table 9]

[0072] [Table 10]

[0073] [Table 11] [Explanation of symbols]

[0074] 1...paper substrate, 2...layer containing polyvinyl alcohol-based resin, 3...vapor-deposited layer, 4...layer containing polyolefin, 10...gas barrier laminate, 20...gusset bag, B1, B2...folded portions.

Claims

1. A gas barrier laminate that includes a paper substrate and a vapor deposition layer and can be sealed by heat sealing. So, 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, and the oxygen permeability at 30°C and 70% RH is 2 cc / m ２ / d / atm 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 the water vapor permeability was measured at 40°C and 90% RH. ２ - day or less, and the oxygen permeability at 30°C and 70% RH is 5 cc / m ２ The paper substrate is folded with the inside facing inward, a 2 kg roller is rolled over it once, and the fold is opened and measured. The water vapor transmission rate at 40°C and 90% RH is 4 g / m or less. ２ - day or less, and the oxygen permeability at 30°C and 70% RH is 5 cc / m ２ / d / atm 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 gas barrier laminate further comprises a layer containing a polyvinyl alcohol resin between the paper substrate and the vapor-deposited layer.

2. 2. 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.

3. The gas barrier laminate according to claim 1 or 2, wherein the layer containing the polyvinyl alcohol-based resin is provided on a surface of the paper substrate.

4. 4. The gas barrier laminate according to claim 1, wherein the thickness of the paper substrate is 70% or more of the total thickness of the gas barrier laminate.

5. 5. 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.

6. 6. The gas barrier laminate according to claim 1, further comprising 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, on a surface of the vapor-deposited layer opposite to the paper substrate.

7. The gas barrier laminate according to claim 6, wherein the thickness of the polyolefin-containing layer is 0.5 μm or more and 10 μm or less.

8. A packaging bag comprising the gas barrier laminate according to any one of claims 1 to 7, wherein the packaging bag has a heat seal strength of 3 N / 15 mm or more.

9. The packaging bag according to claim 8, having a heat seal strength of 10 N / 15 mm or less.

10. The packaging bag according to claim 8 or 9, which has a folded portion.

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