Gas barrier laminates and packaging bags

Abstract

The gas barrier laminate of the present invention is a gas barrier laminate comprising a paper substrate and a vapor-deposited layer and capable of being sealed by heat sealing, wherein the area mass of the paper substrate is 30–100 g / m². 2 The water vapor permeability and oxygen permeability of the gas barrier laminate are respectively within specific ranges.

Description

Technical Field

[0001] This invention relates to gas barrier laminates and packaging bags. Background Technology

[0002] Packaging materials are used in various sectors, including food, beverages, pharmaceuticals, and chemicals, to address the specific contents of each product. These materials require gas barrier properties to prevent the permeation of substances that could cause spoilage, such as oxygen and water vapor.

[0003] In recent years, with the rise of environmental awareness, starting with issues such as marine plastic waste, the opportunity to move away from plastics has increased. From the perspective of reducing the use of plastic materials, the use of paper to replace plastic materials is being explored in various fields. For example, Patent Document 1 discloses a gas barrier laminate in which barrier layers are stacked on paper.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-69783 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] Paper is easy to process due to its crease retention (also known as dead crease retention). However, according to the research of the inventors, there is still room for improvement in terms of cracking in the barrier layer and reduced gas barrier properties when making packaging bags with sharper creases (pillow bag packaging, three-side seal packaging, and gusseted bag packaging).

[0009] Furthermore, from the perspective of the Resource Effective Utilization Promotion Law, it is also required to reduce the amount of plastic materials used in gas barrier laminates.

[0010] The present invention was made in view of the above facts, and its object is to provide a gas barrier laminate having crease retention characteristics as paper, sufficient gas barrier properties even after bending, and contributing to the reduction of plastic material usage, as well as a packaging bag comprising the gas barrier laminate.

[0011] Means for solving technical problems

[0012] This invention provides a gas barrier laminate comprising a paper substrate and a vapor-deposited layer, which is heat-sealed. The paper substrate has a unit area mass of 30–100 g / m². 2 The water vapor permeability of the gas barrier laminate at 40°C and 90% RH is 3 g / m³. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 2cc / m2 Below / d / atm, the water vapor permeability measured at 40°C and 90% RH with the paper substrate as the outer side folded, rolled once on a 2kg roller, and the crease opened is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 Below / d / atm, the water vapor permeability measured at 40℃ and 90%RH with the paper substrate as the inside, rolled once on a 2kg roller, and the crease opened, is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 / d / atm or less; the weight of the paper substrate relative to the total mass of the gas barrier laminate is more than 47% by mass.

[0013] The weight of the paper substrate can also be more than 60% by mass relative to the total amount of the gas barrier laminate.

[0014] The present invention also provides a gas barrier laminate, which is a gas barrier laminate having a paper substrate and a vapor-deposited layer and being capable of being sealed by heat sealing, wherein the area mass of the paper substrate is 30-100 g / m². 2 The water vapor permeability of the gas barrier laminate at 40°C and 90% RH is 3 g / m³. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 2cc / m 2 Below / d / atm, the water vapor permeability measured at 40°C and 90% RH with the paper substrate as the outer side folded, rolled once on a 2kg roller, and the crease opened is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 Below / d / atm, the water vapor permeability measured at 40℃ and 90%RH with the paper substrate as the inside, rolled once on a 2kg roller, and the crease opened, is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70% RH is 5cc / m 2 / d / atm or less; the thickness of the paper substrate is more than 60% relative to the overall gas barrier laminate.

[0015] The thickness of the paper substrate can also be more than 70% of the overall thickness of the gas barrier laminate.

[0016] The vapor-deposited layer may also have a layer on the side opposite to the paper substrate containing a polyolefin having at least one of the following: a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic ester.

[0017] A layer containing polyvinyl alcohol resin can also be provided between the paper substrate and the vapor-deposited layer.

[0018] The present invention also provides a packaging bag comprising the gas barrier laminate of the present invention described above, wherein the heat seal strength is 3N / 15mm or higher.

[0019] The aforementioned packaging bags may also have a bend.

[0020] Invention Effects

[0021] According to the present invention, it is possible to provide a gas barrier laminate having crease retention characteristics as paper, sufficient gas barrier properties even after bending, and contributing to the reduction of plastic material usage, as well as a packaging bag comprising the gas barrier laminate. Attached Figure Description

[0022] Figure 1 This is a schematic cross-sectional view of a gas barrier laminate according to an embodiment of the present invention.

[0023] Figure 2 This is a perspective view of a packaging body according to an embodiment of the present invention. Detailed Implementation

[0024] The following is a reference to the appendix, depending on the circumstances. Figure 1 The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the following embodiments.

[0025] <Gas Barrier Laminate>

[0026] The gas barrier laminate of this embodiment is a gas barrier laminate having a paper substrate and a vapor-deposited layer, and capable of being sealed by heat sealing. The gas barrier laminate 10 of this embodiment is, for example, as shown in the example... Figure 1 As shown, it may include at least a paper substrate 1, a layer 2 containing a polyvinyl alcohol resin, a vapor-deposited layer 3, and a layer 4 containing a polyolefin. Alternatively, for example, a layer containing a polyolefin may be further provided between the paper substrate and the vapor-deposited layer, and the vapor-deposited layer may have two or more layers, including two or more layers containing a polyolefin and a layer containing a polyvinyl alcohol resin.

[0027] [Paper substrate]

[0028] There are no particular limitations on paper substrates; the appropriate choice should be made based on the intended use of the packaging material in the gas barrier laminate. Specific examples of paper substrates include high-grade paper, specialty high-grade paper, coated paper, art paper, cast-coated paper, molded paper, kraft paper, and cellophane.

[0029] The surface area mass of the paper substrate is 30–100 g / m². 2 Preferably, it is 35–90 g / m2 More preferably 40–80 g / m 2 The mass of the paper per unit area is 30 g / m². 2 When the above is the case, it is preferred as it has good physical strength or processing suitability as a packaging bag; on the other hand, when it is 100g / m³, it is preferable. 2 In the following cases, it is preferred as a packaging bag with good flexibility or productivity.

[0030] The weight of the paper substrate, based on the total amount of the gas barrier laminate, 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. If the weight of the paper substrate is 47% by mass or more based on the total amount of the gas barrier laminate, the amount of plastic used can be sufficiently reduced; if it is 50% by mass or more, it can be said that the entire gas barrier laminate is made of paper, and it also has excellent recyclability. There is no particular upper limit to the weight of the paper substrate; for example, it can be less than 100% by mass or less than 90% by mass.

[0031] The thickness of the paper substrate relative to the overall thickness of the gas barrier laminate is preferably 60% or more, more preferably 70% or more. If the thickness of the paper substrate is 60% or more relative to the overall thickness of the gas barrier laminate, the amount of plastic used can be significantly reduced, and the gas barrier laminate as a whole can be considered paper-based, while also exhibiting excellent recyclability. There is no particular upper limit to the thickness of the paper substrate; for example, it can be less than 100%, or even less than 90%. The thickness of the paper substrate can be, for example, 30 μm or more and 100 μm or less, or 35 μm or more and 80 μm or less.

[0032] A coating layer can also be applied to at least the side of the paper substrate that contacts the vapor-deposited layer described later. By applying the coating layer, it acts as a filler to bury the unevenness of the paper, allowing for a defect-free and uniform vapor-deposited film formation. In the coating layer, the adhesive resin can be, for example, various copolymers such as polyolefin-based, styrene-butadiene-based, styrene-acrylic-based, and ethylene-vinyl acetate-based resins, as well as polyvinyl alcohol-based resins, cellulose-based resins, and paraffin wax (WAX). The filler can include, for example, clay, kaolin, calcium carbonate, talc, and mica.

[0033] There are no particular limitations on the thickness of the coating layer; for example, it can be 1–10 μm or 3–8 μm.

[0034] <Vapor Deposition Layer>

[0035] Evaporated layers impart water vapor barrier properties to gas barrier laminates and are layers deposited with metals or metal oxides. Evaporated layers can be obtained by evaporating aluminum or may contain aluminum oxide (Al₂O₃). x ), silicon dioxide (SiO)x (etc.) By adding a vapor-deposited layer, the gas barrier properties of the gas barrier laminate can be improved, thereby reducing the amount of plastic used in the gas barrier laminate.

[0036] The thickness of the vapor-deposited layer can be appropriately set according to the application, preferably 10nm or more, 30nm or more, or 50nm or more, and can be less than 500nm, less than 100nm, or less than 80nm. By making the thickness of the vapor-deposited layer more than 10nm, it is easy to make the continuity of the vapor-deposited layer sufficient, and by making it less than 500nm, the occurrence of curling or cracking can be effectively suppressed, and sufficient gas barrier performance and flexibility can be easily achieved.

[0037] From the perspective of gas barrier properties or film uniformity, vapor-deposited layers are preferably formed using vacuum deposition methods. Known methods include vacuum deposition, sputtering, and chemical vapor deposition (CVD). Vacuum deposition is preferred due to its fast deposition rate and high productivity. Furthermore, among vacuum deposition methods, electron beam heating is particularly effective because it allows for easy control of the deposition rate by adjusting the irradiation area or electron beam current, and because the heating and cooling of the deposition material can be performed quickly.

[0038] When there are multiple vapor-deposited layers, they can be vapor-deposited layers using the same material or vapor-deposited layers using different materials.

[0039] [Layer containing polyvinyl alcohol resin]

[0040] A layer containing a polyvinyl alcohol (PVA) resin is provided on the surface of a paper substrate, for example, to improve the adhesion between the paper substrate and the vapor-deposited layer, or to improve the gas barrier properties (especially oxygen barrier properties) of the gas barrier laminate. PVA resins include, for example, fully saponified PVA resin, partially saponified PVA resin, modified PVA resin, and ethylene-vinyl alcohol copolymer resin. Furthermore, the degree of polymerization of the PVA resin is preferably 300 or higher and 1500 or lower. If the degree of polymerization is 300 or higher, the barrier properties or flexural strength of the gas barrier laminate become better; if the degree of polymerization is 1500 or lower, the viscosity of the PVA resin coating solution described later decreases, and the coatability becomes better.

[0041] As a method for setting a layer containing a polyvinyl alcohol-based resin, it can be obtained, for example, by coating a paper substrate with a coating solution containing the aforementioned polyolefin polyvinyl alcohol-based resin and solvent and then drying it. Examples of solvents included in the coating solution include water, methanol, ethanol, isopropanol, n-propanol, n-butanol, n-pentanol, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide; a mixture of water and alcohols such as methanol, ethanol, and isopropanol is particularly preferred. Furthermore, the coating solution may also contain additives such as surfactants or preservatives, preservation stabilizers, silane coupling agents, organotitanates, polyolefin emulsions, and defoamers.

[0042] This layer containing polyvinyl alcohol resin has excellent flexibility. When bent, it can inhibit the cracking of the vapor-deposited layer, inhibit the deterioration of gas barrier properties, and improve the adhesion between the vapor-deposited layer and the layer containing polyvinyl alcohol resin.

[0043] The thickness of the layer containing polyvinyl alcohol resin can 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 can be efficiently filled, and the vapor-deposited layer can be uniformly stacked. On the other hand, if the thickness is 5 μm or less, the vapor-deposited layer can be uniformly stacked while reducing costs.

[0044] <Layer containing polyolefin>

[0045] The gas barrier laminate of this embodiment may have a layer containing polyolefin on at least one side of the vapor-deposited layer opposite to the paper substrate, preferably a layer containing at least one polyolefin having a carboxyl group, a salt of a carboxyl group, a carboxylic anhydride group, and a carboxylic ester. By having such a polyolefin-containing layer, the water vapor barrier property can be improved due to the crystallinity of the polyolefin, thereby improving the adhesion to the vapor-deposited layer, preventing the vapor-deposited layer from breaking due to bending, and at the same time, giving the gas barrier laminate heat-sealing properties. By combining multiple functions in this way, it is not necessary to provide an additional adhesive layer or protective layer, or a heat-sealing resin layer, thus reducing the amount of plastic used.

[0046] The aforementioned layer containing polyolefin is preferably an aqueous emulsion coating, drying, or film coating, and preferably contains a polyolefin emulsion having at least one selected from carboxyl groups, carboxyl salts, carboxylic anhydrides, and carboxylic esters.

[0047] When multiple layers containing polyolefins exist, they can be made of the same material or different materials.

[0048] As a method for setting a layer containing polyolefin, it can be obtained by coating a vapor-deposited layer with a coating solution containing the material constituting the above-mentioned resin layer and a solvent and then drying it. Examples of solvents included in the coating solution include water, methanol, ethanol, isopropanol, n-propanol, n-butanol, n-pentanol, dimethyl sulfoxide, dimethylformamide, and dimethylacetamide; a mixture of water and alcohols such as methanol, ethanol, and isopropanol is particularly preferred. Furthermore, the coating solution may also contain additives such as surfactants or preservatives, preservation stabilizers, silane coupling agents, organotitanates, anti-caking agents, slip agents, and defoamers.

[0049] The thickness of the polyolefin-containing layer can be, for example, 0.5 μm or more and 10 μm or less. When the film thickness is 0.5 μm or more, it is easy to obtain sufficient heat-sealing strength and barrier properties, while when it is 10 μm or less, costs can be suppressed, and the paper ratio of the gas barrier laminate of this embodiment can be increased.

[0050] The gas barrier laminate of this embodiment maintains sufficient gas barrier properties even after bending. In this specification, gas barrier properties refer to sufficiently low water vapor permeability and oxygen permeability.

[0051] <Water vapor permeability>

[0052] The water vapor permeability of the gas barrier laminate in this embodiment, when measured using the MOCON method, is preferably 3 g / m³ under conditions of 40°C and 90% RH. 2 • Less than 1 day, preferably 2g / m 2 • Less than 1 day. Water vapor permeability is 3 g / m 2 For packaging bags using this gas barrier laminate, the deterioration caused by moisture absorption or evaporation of the contents can be inhibited for a long period of time.

[0053] In this embodiment, the gas barrier laminate is folded with the paper substrate as the outer side, rolled once on a 2kg roller, and the water vapor transmission rate is measured after opening the crease. The water vapor transmission rate is preferably 4g / m³ under the conditions of 40°C and 90% RH. 2 • For days or less, 3g / m² is preferred. 2 • Day or less.

[0054] In this embodiment, the gas barrier laminate is folded with the paper substrate as the inner side, rolled once on a 2kg roller, and the water vapor transmission rate is measured after opening the crease. The water vapor transmission rate is preferably 4g / m³ under the conditions of 40°C and 90% RH. 2 • For days or less, 3g / m² is preferred. 2• Less than 1 day. Water vapor permeability through the crease is 4 g / m. 2 Even with creases such as pillowcases, three-sided sealed bags, and gusseted bags, the contents can be kept moist for up to 1 day, preventing deterioration caused by moisture absorption or evaporation.

[0055] <Oxygen permeability>

[0056] When the oxygen permeability of the gas barrier laminate in this embodiment is measured using JIS K7126, Method B (isobaric method) at a temperature of 30°C and a relative humidity of 70% RH, it is preferably 2 cc / m. 2 Below / d / atm, preferably 1cc / m 2 Below / d / atm. Oxygen permeability is 2cc / m. 2 Packaging bags using this gas barrier laminate with a capacity of / d / atm or less can inhibit the deterioration caused by oxidation of the contents for a long period of time.

[0057] In this embodiment, the gas barrier laminate is folded with the paper substrate on the outside, rolled once on a 2kg roller, and the oxygen permeability measured at 30°C and 70% RH after opening the crease is preferably 5cc / m. 2 Below / d / atm, preferably 3cc / m 2 / d / atm and below.

[0058] In this embodiment, the gas barrier laminate is folded with the paper substrate as the inner side, rolled once on a 2kg roller, and the oxygen permeability measured at 30°C and 70% RH after opening the crease is preferably 5cc / m. 2 Below / d / atm, preferably 3cc / m 2 Below / d / atm. Oxygen permeability through the crease is 5cc / m. 2 Even with creases such as pillowcases, three-side sealed bags, and gusseted bags, packaging below / d / atm can inhibit the deterioration caused by oxidation of the contents for a long time.

[0059] <Packaging Bags>

[0060] Figure 2 This is a perspective view of a gusseted bag 20 formed by a gas barrier laminate 10. The bag is manufactured by sealing the opening at the top of the gusseted bag 20. The gusseted bag 20 has bent portions (bending portions B1 and B2) of the gas barrier laminate 10. Bending portion B1 is the portion where the gas barrier laminate is folded when viewed from the innermost layer, while bending portion B2 is the portion where the gas barrier laminate 10 is folded when viewed from the innermost layer.

[0061] Packaging bags can be made by folding a single gas barrier laminate twice with the opposite sides of the paper substrate facing each other, bending it appropriately to form the desired shape, and then heat-sealing it. Alternatively, two gas barrier laminates can be overlapped with the opposite sides of the paper substrate facing each other and then heat-sealed to form the same shape.

[0062] In this embodiment, the heat seal strength of the packaging bag can be 3 N / 15 mm or higher, or 4 N / 15 mm or higher. Furthermore, there is no particular limitation on the upper limit of the heat seal strength; for example, it can be 10 N / 15 mm or lower. If the heat seal strength is 3 N / 15 mm or higher, the contents can be protected during various distribution processes until the packaging bag is opened.

[0063] The packaging bag can hold food, medicine, and other contents. It is particularly suitable for storing snacks and other food items. Even with a folded shape, the packaging bag of this embodiment maintains high gas barrier properties. Furthermore, due to the high paper content, it has the potential to be recycled after use, reducing the amount of plastic waste.

[0064] Furthermore, while an accordion bag is cited as an example of a packaging bag in this embodiment, other types of bags, such as pillow bags, three-side seal bags, or stand-up pouches, can also be made using the gas barrier laminate of this embodiment.

[0065] Example

[0066] The present invention will be described in more detail below through examples, but the present invention is not limited to these examples.

[0067] <Fabrication of Gas Barrier Laminates>

[0068] (Examples 1-12, Comparative Example 1)

[0069] A gas barrier laminate with the configuration shown in Tables 1 to 4 below is fabricated by sequentially forming a layer containing a polyvinyl alcohol resin, a vapor-deposited layer, and a layer containing a polyolefin on the surface of a clay coating on a paper substrate. The polyvinyl alcohol resin layer and the polyolefin layer are formed by applying a coating solution using a bar coater and drying it in an oven. The vapor-deposited layer is formed using a vacuum vapor deposition method. The materials used are described below.

[0070] Clay-coated paper: Paper thickness: 50μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 60g / m² 2 (Paper: 43.6g / m³) 2 Clay coating: 16.4g / m 2 )

[0071] Clay-coated paper: Paper thickness: 30μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 40g / m² 2 (Paper: 24.6g / m³) 2 Clay coating: 15.4g / m 2 )

[0072] Clay-coated paper: Paper thickness: 100μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 100g / m² 2 (Paper: 84.2g / m³) 2 Clay coating: 15.8g / m 2 )

[0073] • Polyvinyl alcohol: Saponification degree 98%, polymerization degree 500 (made by Kuraray)

[0074] • Modified polyvinyl alcohol: Exceval RS-4104 (manufactured by Kuraray)

[0075] • Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salts (Mitsui Chemicals)

[0076] The "Ratio of Paper Substrate Weight" in the table is based on the total weight of the gas barrier laminate, and the "Ratio of Paper Substrate Thickness" is based on the overall thickness of the gas barrier laminate.

[0077] (Examples 13-24, Comparative Examples 2-3)

[0078] A gas barrier laminate with the configuration shown in Tables 5 to 8 is fabricated by sequentially forming a layer containing a polyolefin, a layer containing a polyvinyl alcohol resin, a vapor-deposited layer, and another layer containing a polyolefin on the surface of a clay coating on a paper substrate. The polyvinyl alcohol resin layer and the polyolefin layer are formed by applying a coating solution using a bar coater and drying it in an oven. The vapor-deposited layer is formed using a vacuum vapor deposition method. The materials used are described below.

[0079] Clay-coated paper: Paper thickness: 50μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 60g / m² 2 (Paper: 43.6g / m³) 2Clay coating: 16.4g / m 2 )

[0080] Clay-coated paper: Paper thickness: 30μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 40g / m² 2 (Paper: 24.6g / m³) 2 Clay coating: 15.4g / m 2 )

[0081] Clay-coated paper: Paper thickness: 100μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 100g / m² 2 (Paper: 84.2g / m³) 2 Clay coating: 15.8g / m 2 )

[0082] • Polyvinyl alcohol: Saponification degree 98%, polymerization degree 500 (made by Kuraray)

[0083] • Modified polyvinyl alcohol: Exceval RS-4104 (manufactured by Kuraray)

[0084] • Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salts (Mitsui Chemicals)

[0085] (Examples 25-32)

[0086] A gas barrier laminate with the configuration shown in Tables 9 and 10 below is fabricated by sequentially forming a layer containing polyolefin, a vapor-deposited layer, a layer containing polyvinyl alcohol resin, another vapor-deposited layer, and another layer containing polyolefin on the surface of a clay coating on a paper substrate. The layers containing polyvinyl alcohol resin and polyolefin are formed by applying a coating solution using a bar coater and drying it in an oven. The vapor-deposited layer is formed using a vacuum vapor deposition method. The materials used are described below.

[0087] Clay-coated paper: Paper thickness: 50μm, Paper density: 0.8g / cm³ 3 Clay coating thickness: 5μm; Clay coating density: 3g / cm³ 3 Mass per unit area: 60g / m² 2 (Paper: 43.6g / m³) 2 Clay coating: 16.4g / m 2 )

[0088] • Polyvinyl alcohol: Saponification degree 98%, polymerization degree 500 (made by Kuraray)

[0089] • Modified polyvinyl alcohol: Exceval RS-4104 (manufactured by Kuraray)

[0090] • Chemipearl S100: Aqueous dispersion of polyolefin containing carboxyl salts (Mitsui Chemicals)

[0091] • Chemipearl S500: Aqueous dispersion of polyolefin containing carboxyl salts (Mitsui Chemicals)

[0092] Chemipearl V300: Aqueous dispersion of vinyl acetate-based polyolefins (Mitsui Chemicals).

[0093] (Comparative Example 4)

[0094] A coating solution containing amide alkyd resin 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 layer containing amide alkyd resin. The layer thickness was 4 μm. Next, Al vapor deposition was performed on this layer. The Al vapor deposition layer thickness was 50 nm. Then, a coating solution containing polyvinyl alcohol resin and TEOS was applied to the Al vapor deposition 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. Next, a coating solution containing a carboxyl salt (trade name: Chemipearl S500, manufactured by Mitsui Chemicals) was applied using a bar coater, and dried in an oven to form a layer containing polyolefin, obtaining a gas barrier laminate. The polyolefin layer thickness was 3 μm.

[0095] (Comparative Example 5)

[0096] A coating solution containing a 15 μm thick water-vapor barrier resin layer was formed by coating a clay-coated paper (paper thickness: 50 μm, clay coating thickness: 5 μm) with an aqueous dispersion of kaolin (Barrisurf HX, IMERYS) and a styrene-acrylic copolymer emulsion (Saiden Chemical X-511-374E) at a solids ratio of 1:1 using a bar coater. The mixture was then dried in an oven. Next, an aqueous solution of polyvinyl alcohol (PVA117, Kuraray) was coated onto this layer using a bar coater, and the mixture was dried in an oven to form a gas barrier layer with a thickness of 5 μm. Finally, a 30 μm thick layer of low-density polyethylene (LC602A, Polyethylene Japan) was laminated using an extrusion lamination method to obtain a gas barrier laminate.

[0097] (Comparative Example 6)

[0098] A 30 μm thick layer of low-density polyethylene (LC602A, manufactured by Polyethylene Corporation of Japan) was laminated onto a silica-deposited PET film (GL film manufactured by Toppan Printing Co., Ltd., 12 μm thick) using an extrusion lamination method with a polyurethane-based anchoring agent. The silica-deposited PET film side of this laminated film was then coated with a dry weight of 5 g / m². 2 A two-component curing adhesive coated with polyurethane is dry-laminated with paper (clay-coated paper, paper thickness: 50 μm, clay coating thickness: 5 μm) to obtain a gas barrier laminate.

[0099] <Determination of Water Vapor Transmission>

[0100] The water vapor transmission rate of the gas barrier laminates in the examples and comparative examples was determined using the MOCON method. The measurement conditions were a temperature of 40°C and a relative humidity of 90%. A 2kg roller was rolled once at a speed of 300mm / min while creases were applied to the gas barrier laminate. The water vapor transmission rate of the unfolded gas barrier laminate was also measured in the same manner. Furthermore, in Tables 1-11, "valley fold" indicates a gas barrier laminate with a valley fold as observed from the paper substrate side, and "mountain fold" indicates a gas barrier laminate with a mountain fold as observed from the paper substrate side. The units in Tables 1-11 are [g / m³]. 2 ·day] indicates the result.

[0101] <Determination of Oxygen Permeability>

[0102] The oxygen permeability of the gas barrier laminates of the examples and comparative examples was determined using JIS K7126, Method B (isobaric method). A MOCON OXTRAN 2 / 20 apparatus was used for the measurement, which was conducted at 30°C and 70% relative humidity. Tables 1-11 use units [cc / m³]. 2 [ / d / atm] indicates the result.

[0103] <Determination of heat seal strength>

[0104] Two gas barrier laminates were overlapped with the paper substrate facing outwards. They were then heat-sealed at 120°C, 0.2 MPa, and for 1 second using a heat sealer. A 15 mm wide strip was then cut from the laminate, and the maximum load during T-shaped peeling at a peeling speed of 300 mm / min was measured. Results are expressed in Tables 1-11 using the unit [N / 15 mm].

[0105] Performance Evaluation of Gas Barrier Packaging Bags

[0106] Gas barrier laminates were cut into 8cm × 18cm pieces to make gusseted bags. These bags were then filled with baked goods (cookies) and sealed. The sealed bags were stored for one month at 40°C and 90% relative humidity. Afterward, the contents were removed, and the appearance and taste were checked. No change before and after storage was marked as "0", and significant changes were marked as "×". The results are shown in Tables 1 to 11.

[0107] <Evaluation of the Recyclability of Recycled Paper>

[0108] 150g of the gas barrier laminate was weighed and subjected to dissociation treatment in alkaline water. The plastic component was removed, and the laminate was washed with water. The dry weight of the recoverable pulp fibers was measured. Cases where more than 70g of pulp fibers could be recovered were judged as recyclable and marked "0", while cases where less than 50g of pulp fibers could be recovered were judged as not recyclable and marked "×", as shown in Tables 1-11.

[0109] [Table 1]

[0110]

[0111] [Table 2]

[0112]

[0113] [Table 3]

[0114]

[0115] [Table 4]

[0116]

[0117] [Table 5]

[0118]

[0119] [Table 6]

[0120]

[0121] [Table 7]

[0122]

[0123] [Table 8]

[0124]

[0125] [Table 9]

[0126]

[0127] [Table 10]

[0128]

[0129] [Table 11]

[0130]

[0131] Symbol Explanation

[0132] 1. Paper substrate, 2. Layer containing polyvinyl alcohol resin, 3. Evaporated layer, 4. Layer containing polyolefin, 10. Gas barrier laminate, 20. Gusseted bag, B1, B2. Bending section.

Claims

1. A gas barrier laminate, which is a gas barrier laminate that can be sealed by heat sealing, comprising: Paper substrate; A layer containing polyvinyl alcohol-based resin; Evaporated coating; and The layer comprises a polyolefin having at least one group selected from carboxyl groups, salts of carboxyl groups, carboxylic anhydride groups, and carboxylic ester groups. in, The layer containing polyvinyl alcohol resin is disposed on the surface of the paper substrate. The unit area mass of the paper substrate is 30~100g / m². 2 ; The thickness of the layer containing polyvinyl alcohol resin is more than 1 μm and less than 5 μm. The water vapor permeability of the gas barrier laminate at 40°C and 90%RH is 3 g / m³. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 2cc / m 2 Below / d / atm The paper substrate is folded with the outer side facing outwards, rolled once on a 2kg roller, and the water vapor permeability measured at 40°C and 90%RH after opening the crease is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 5cc / m 2 Below / d / atm, the water vapor permeability measured at 40°C and 90%RH with the paper substrate as the inside folded and rolled once on a 2kg roller is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 5cc / m 2 Below / d / atm; The weight of the paper substrate is more than 47% by mass relative to the total weight of the gas barrier laminate.

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

3. A gas barrier laminate, which is a gas barrier laminate that can be sealed by heat sealing, comprising: Paper substrate; A layer containing polyvinyl alcohol-based resin; Evaporated coating; and The layer comprises a polyolefin having at least one group selected from carboxyl groups, salts of carboxyl groups, carboxylic anhydride groups, and carboxylic ester groups. in, The layer containing polyvinyl alcohol resin is disposed on the surface of the paper substrate. The unit area mass of the paper substrate is 30~100g / m². 2 ; The thickness of the layer containing polyvinyl alcohol resin is more than 1 μm and less than 5 μm. The water vapor permeability of the gas barrier laminate at 40°C and 90%RH is 3 g / m³. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 2cc / m 2 Below / d / atm The paper substrate is folded with the outer side facing outwards, rolled once on a 2kg roller, and the water vapor permeability measured at 40°C and 90%RH after opening the crease is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 5cc / m 2 Below / d / atm, the water vapor permeability measured at 40°C and 90%RH with the paper substrate as the inside folded and rolled once on a 2kg roller is 4g / m. 2 • Below day, the oxygen permeability at 30℃ and 70%RH is 5cc / m 2 Below / d / atm; The thickness of the paper substrate is more than 60% relative to the overall gas barrier laminate.

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

5. The gas barrier laminate according to any one of claims 1 to 4, wherein, A coating layer is provided on the surface of the paper substrate on the side containing the polyvinyl alcohol resin. The coating layer comprises an adhesive resin and fillers. The adhesive resin is selected from at least one of polyolefin copolymers, styrene-butadiene copolymers, styrene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, cellulose resins, and paraffin wax. The filler is selected from at least one of clay, kaolin, calcium carbonate, talc, and mica.

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

7. The packaging bag according to claim 6, wherein it has a bent portion.

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