Gas barrier laminate

Abstract

This gas barrier laminate comprises: a paper substrate; and, in order on at least one surface of the paper substrate, an oxygen barrier layer and a water vapor barrier layer. The oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of 50 or less and an average particle diameter of 3 μm or less; the water-soluble resin contains at least one selected from the group consisting of polyvinyl alcohols and modified polyvinyl alcohols having a saponification degree of 93% or more; the content of the inorganic compound is 150 to 540 parts by mass with respect to 100 parts by mass of the water-soluble resin; and the water vapor barrier layer contains a water dispersible resin.

Description

Gas barrier laminate

[0001] The present invention relates to a gas barrier laminate.

[0002] Conventionally, a gas barrier laminate has been known which is configured to provide a paper substrate with an oxygen barrier layer and a water vapor barrier layer in this order in order to impart gas barrier properties (oxygen barrier properties) and water vapor barrier properties to the paper substrate.

[0003] Patent Document 1 describes a barrier laminate having a paper base material and, on at least one surface of the paper base material, a gas barrier layer and a water vapor barrier layer in this order, wherein the gas barrier layer contains one or more binders selected from the group consisting of water-soluble resin binders and water-dispersible resin binder 1, and the water vapor barrier layer contains a layered inorganic compound, a cationic resin, and water-dispersible resin binder 2, wherein water-dispersible resin binder 1 and water-dispersible resin binder 2 are different, the aspect ratio of the layered inorganic compound is a specific value or more, the thickness of the layered inorganic compound is a specific value or less, and the content of the layered inorganic compound in the water vapor barrier layer is within a specific range.

[0004] Patent No. 6870797

[0005] The barrier laminate described in Patent Document 1 has room for improvement in oxygen barrier properties when the gas barrier layer contains a water-soluble resin binder, particularly when a water-based water vapor barrier layer coating is applied to the gas barrier layer. Also, when the gas barrier layer contains a water-dispersible resin binder to improve water resistance, there is an issue with disintegration properties when the laminate is reused.

[0006] The present invention has been made in view of the existence of the above problems, and has an object to provide a gas barrier laminate that has excellent oxygen barrier properties, water vapor barrier properties, and also excellent disintegration properties.

[0007]

[0016] The present inventors have discovered that a gas barrier laminate having a paper base and, on at least one surface of the paper base, an oxygen barrier layer and a water vapor barrier layer, in this order, wherein the oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of a specific value or less and an average particle size of a specific value or less, the water-soluble resin contains at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, each having a saponification degree of 93% or more, the inorganic compound content being within a specific range, and the water vapor barrier layer contains a water-dispersible resin, thereby achieving excellent oxygen barrier property, water vapor barrier property, and disintegration property. That is, the present invention relates to the following <1> to <18>. <1> A gas barrier laminate comprising a paper base material and, on at least one surface of the paper base material, an oxygen barrier layer and a water vapor barrier layer, in this order, wherein the oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of 50 or less and an average particle size of 3 μm or less, the water-soluble resin contains at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, each having a saponification degree of 93% or more, the content of the inorganic compound being 150 parts by mass or more and 540 parts by mass or less per 100 parts by mass of the water-soluble resin, and the water vapor barrier layer contains a water-dispersible resin. <2> The gas barrier laminate according to <1>, wherein the water-soluble resin contains polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more but less than 700, and polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more and 2500 or less. <3> The gas barrier laminate according to <2>, wherein the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more and less than 700 to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more and 2500 or less is 5:95 to 60:40. <4> The gas barrier laminate according to <1>, wherein the water-soluble resin contains polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more and 500 or less, and polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more and 1200 or less.<5> The gas barrier laminate according to <4>, wherein the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more and 500 or less to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more and 1200 or less, in the water-soluble resin, is 5:95 to 60:40. <6> The gas barrier laminate according to any one of <1> to <5>, wherein the oxygen barrier layer further contains a layered inorganic compound having an aspect ratio of 80 or more, and the content of the layered inorganic compound is 25 parts by mass or less per 100 parts by mass of the water-soluble resin. <7> The gas barrier laminate according to any one of <1> to <6>, wherein the inorganic compound contains kaolin. <8> The gas barrier laminate according to any one of <1> to <7>, wherein the water-dispersible resin contains a styrene / acrylic copolymer. <9> The gas barrier laminate according to any one of <1> to <8>, wherein the water vapor barrier layer further contains a wax. <10> The gas barrier laminate according to <9>, wherein the wax contains paraffin wax. <11> The oxygen barrier layer is applied in an amount of 1 g / m. ２ 15g / m or more ２ <12> The gas barrier laminate according to any one of <1> to <10>, wherein the amount of the water vapor barrier layer applied is 4 g / m or less. ２ 8g / m or more ２ <13> The gas barrier laminate according to any one of <1> to <11>, wherein the water vapor permeability is 20 g / (m ２ <14> The gas barrier laminate according to any one of <1> to <12>, wherein the oxygen permeability is 30 mL / (m ２<16> A packaging bag made using the gas barrier laminate according to any one of <1> to <15>. <17> A method for producing the gas barrier laminate according to any one of <1> to <15>, comprising a step of laminating an oxygen barrier layer and a water vapor barrier layer on at least one surface of the paper base material, wherein the water-soluble resin contains polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa·s or more and 6 mPa·s or less in a 4% aqueous solution at 20°C, and polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa·s or more and 35 mPa·s or less in a 4% aqueous solution at 20°C. <18> The method for producing a gas barrier laminate according to <17>, wherein the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa s or more and 6 mPa s or less in a 4% aqueous solution at 20°C to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 35 mPa s or less in a 4% aqueous solution at 20°C is 5:95 to 60:40.

[0008] [Gas barrier laminate] The gas barrier laminate of this embodiment (hereinafter also simply referred to as "gas barrier laminate") is a gas barrier laminate comprising a paper base material and, on at least one surface of the paper base material, an oxygen barrier layer and a water vapor barrier layer, in this order, wherein the oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of 50 or less and an average particle size of 3 μm or less, the water-soluble resin contains at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, each having a saponification degree of 93% or more, the content of the inorganic compound is 150 parts by mass or more and 540 parts by mass or less per 100 parts by mass of the water-soluble resin, and the water vapor barrier layer contains a water-dispersible resin.

[0009] It has been revealed that the gas barrier laminate of this embodiment comprises an oxygen barrier layer on at least one surface of a paper substrate, the oxygen barrier layer containing a water-soluble resin having a saponification degree equal to or greater than a specific value and a specific amount of an inorganic compound having an aspect ratio equal to or less than a specific value and an average particle size equal to or less than a specific value, and a water vapor barrier layer containing a water-dispersible resin on the oxygen barrier layer, thereby providing a gas barrier laminate with excellent oxygen barrier and water vapor barrier properties and excellent disintegration properties. The mechanism of this effect is unclear, but is presumed to be as follows. When a two-layer barrier layer having oxygen barrier properties, water vapor barrier properties, and heat sealability is formed on a paper substrate, a single layer having both oxygen barrier properties and heat sealability has not yet been realized, so the second layer, which is the outermost layer, must have water vapor barrier properties and heat sealability. Therefore, the first layer on at least one surface of the paper substrate must be an oxygen barrier layer having oxygen barrier properties. If a water-dispersible resin is added to the oxygen barrier layer to impart oxygen barrier properties to the oxygen barrier layer, the disintegration properties of the gas barrier laminate when reused are poor.

[0003] Therefore, when a water-soluble resin is contained in the oxygen barrier layer to improve disintegration properties, and particularly when a water-based water vapor barrier layer coating material is applied to the oxygen barrier layer, the oxygen barrier layer dissolves and no longer functions properly, tending to result in poor oxygen barrier properties. Furthermore, when a heat seal layer is provided on at least one side of the paper substrate in addition to the water vapor barrier layer and the oxygen barrier layer, disintegration properties are further impaired. Therefore, by incorporating a water-soluble resin containing at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol having a saponification degree of a specific value or more, and a specific amount of an inorganic compound having an aspect ratio and an average particle size of a specific value or less, into the oxygen barrier layer on at least one side of the paper substrate, the oxygen barrier layer functions properly even when a water-based water vapor barrier layer coating material is applied, and as a result, a gas barrier laminate with excellent oxygen barrier properties and excellent disintegration properties can be provided.Furthermore, if the content of the inorganic compound contained in the oxygen barrier layer is 150 parts by mass or more per 100 parts by mass of the water-soluble resin, the oxygen barrier layer will have excellent water resistance. Even if a water-based water vapor barrier layer paint is applied to the oxygen barrier layer, the oxygen barrier layer will not be affected by dissolution or other factors, resulting in excellent oxygen barrier properties and water vapor barrier properties. Furthermore, since the oxygen barrier layer is not affected by dissolution or other factors, the film-formability of the water vapor barrier layer will be improved, resulting in excellent water vapor barrier properties. Furthermore, if the content of the inorganic compound contained in the oxygen barrier layer is 540 parts by mass or less per 100 parts by mass of the water-soluble resin, the inorganic compound can be sufficiently filled with the water-soluble resin, preventing gaps from forming, resulting in excellent oxygen barrier properties. Furthermore, the smoothness of the surface of the oxygen barrier layer is improved, improving the film-formability of the water vapor barrier layer, resulting in excellent water vapor barrier properties. Note that the above mechanism is based on speculation, and the present invention is not limited thereto.

[0010] The gas barrier laminate of this embodiment only needs to have an oxygen barrier layer and a water vapor barrier layer, in this order, on at least one surface of the paper substrate, and may also have an oxygen barrier layer and a water vapor barrier layer, in this order, on the other surface. The gas barrier laminate of this embodiment may also have multiple oxygen barrier layers and water vapor barrier layers, in this order (paper substrate / oxygen barrier layer / water vapor barrier layer / oxygen barrier layer / water vapor barrier layer...), or may have multiple oxygen barrier layers and multiple water vapor barrier layers (paper substrate / oxygen barrier layer / oxygen barrier layer... / water vapor barrier layer / water vapor barrier layer...).

[0011] When the gas barrier laminate of this embodiment is used for packaging of food, etc., it is preferable that the oxygen barrier layer and the water vapor barrier layer are provided in this order on only one side of the paper substrate. With this configuration, when the gas barrier laminate of this embodiment is heat-sealed, a pouch-shaped packaging bag can be easily produced.

[0012] <Paper substrate> The paper substrate used in the gas barrier laminate of this embodiment is preferably a commonly used paper whose main component is plant-derived pulp, and more preferably a paper whose main component is wood pulp. Furthermore, paper whose main component is pulp that is easily dispersed in water by mechanical disintegration is preferred. Specific examples include bleached or unbleached kraft paper, fine paper, paperboard, liner paper, coated paper, one-side glazed paper, glassine paper, graphene paper, etc., and among these, bleached or unbleached kraft paper, fine paper, and one-side glazed paper are preferred. By using a paper substrate, the gas barrier laminate of this embodiment is excellent in terms of reducing environmental impact, recyclability, and ease of disposal.

[0013] (Canadian Standard Freeness (CSF)) The Canadian Standard Freeness (CSF) of the pulp constituting the paper base, measured in accordance with JIS P 8121-2:2012, is preferably 800 mL or less, more preferably 600 mL or less, from the viewpoint of improving gas barrier property and water vapor barrier property, and the lower limit thereof is not particularly limited, but is preferably 150 mL or more. The CSF of the pulp constituting the paper base is measured in accordance with JIS P 8121-2:2012 using a paper base pulp disintegrated in accordance with JIS P 8220-1:2012 as a sample.

[0014] The paper substrate may contain known internal additives, such as fillers such as titanium dioxide, kaolin, talc, and calcium carbonate, internal sizing agents, dry strength agents, wet strength agents, retention aids, pH adjusters, drainage aids, water-resistant agents, softeners, antistatic agents, antifoaming agents, slime control agents, dyes, and pigments.

[0015] In the papermaking of paper substrates, a known wet papermaking machine (for example, a Fourdrinier papermaking machine, a gap former papermaking machine, a cylinder papermaking machine, a short wire papermaking machine, etc.) can be appropriately selected and used. The paper layer formed by the papermaking machine is preferably transported, for example, on a felt and dried in a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying in the dryer.

[0016] The paper substrate obtained as described above may be subjected to a surface treatment using a calendar to make the thickness and profile uniform. For the calendar treatment, a known calendaring machine can be appropriately selected and used.

[0017] (Basis Weight) The basis weight of the paper substrate is preferably 20 g / m from the viewpoint of obtaining an appropriate strength (rigidity) for the gas barrier laminate and from the viewpoint of moldability. ２ More preferably, 30 g / m ２ More preferably, 40 g / m ２ and preferably 500 g / m ２ or less, more preferably 400 g / m ２ More preferably, 300 g / m or less ２ More preferably, 200 g / m or less ２ More preferably, 100 g / m or less ２ The basis weight of the paper substrate is measured in accordance with JIS P 8124:2011.

[0018] (Thickness) From the viewpoint of obtaining an appropriate strength (rigidity) for the gas barrier laminate and from the viewpoint of moldability, the thickness of the paper substrate is preferably 20 μm or more, more preferably 30 μm or more, even more preferably 40 μm or more, still more preferably 50 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less, even more preferably 150 μm or less, and still more preferably 100 μm or less. The thickness of the paper substrate is measured in accordance with JIS P 8118:2014.

[0019] (Density) The density of the paper substrate is preferably 0.5 g / cm from the viewpoint of obtaining an appropriate strength (rigidity) for the gas barrier laminate and from the viewpoint of moldability. ３ More preferably, 0.6 g / cm ３ More preferably, 0.7 g / cm ３ and preferably 1.2 g / cm ３ or less, more preferably 1.0 g / cm ３ The density of the paper substrate is calculated from the basis weight and thickness of the paper substrate obtained by the above-mentioned measurement method.

[0020] <Oxygen Barrier Layer> The oxygen barrier layer is a layer having oxygen barrier properties, particularly preventing the permeation of oxygen gas. The oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of 50 or less and an average particle size of 3 μm or less, the water-soluble resin containing at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, each having a saponification degree of 93% or more, and the content of the inorganic compound is 150 parts by mass or more and 540 parts by mass or less per 100 parts by mass of the water-soluble resin.

[0021] (Water-soluble resin) The water-soluble resin refers to a resin that is soluble in water. The water-soluble resin refers to a resin that dissolves at least 1 g in 100 g of water at any temperature between 0°C and 100°C. Examples of water-soluble resins include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acid and its salts, casein, and polyethyleneimine. Among these, from the viewpoint of improving oxygen barrier properties, the water-soluble resin contains at least one selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, preferably modified polyvinyl alcohol, and more preferably modified polyvinyl alcohol.

[0022]

[0033] The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is 93% or more, preferably 95% or more, more preferably 96% or more, and even more preferably 97% or more, from the viewpoints of increasing crystallinity and improving oxygen barrier property, and of suppressing the influence on the oxygen barrier layer when a water vapor barrier layer described later is provided on the oxygen barrier layer. The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is measured in accordance with JIS K 6726:1994.

[0023] <Viscosity Average Degree of Polymerization> From the viewpoint of improving gas barrier properties, the viscosity average degree of polymerization of polyvinyl alcohol and modified polyvinyl alcohol is preferably 100 or more, more preferably 200 or more, and even more preferably 300 or more, and from the viewpoint of ease of layer formation, it is preferably 2500 or less, more preferably 2000 or less, even more preferably 1700 or less, still more preferably 1400 or less, and even more preferably 1200 or less. When catalog values ​​are available for the viscosity average degrees of polymerization of polyvinyl alcohol and modified polyvinyl alcohol, the catalog values ​​may be used, or when no catalog values ​​are available, they are measured in accordance with JIS K 6726:1994.

[0024]

[0033] The viscosity (20°C, 4% solution) of polyvinyl alcohol and modified polyvinyl alcohol is preferably 1 mPa s or more, more preferably 2 mPa s or more, even more preferably 3 mPa s or more, and still more preferably 10 mPa s or more, from the viewpoint of improving gas barrier property, and from the viewpoint of facilitating layer formation by keeping the viscosity of the coating solution within an appropriate range when forming a gas barrier layer by coating, the viscosity is preferably 40 mPa s or less, more preferably 35 mPa s or less, and even more preferably 30 mPa s or less. The viscosity (20°C, 4% solution) of polyvinyl alcohol and modified polyvinyl alcohol may be measured in accordance with JIS K 6726:1994, if available, or if no catalog value is available, the viscosity may be measured in accordance with JIS K 6726:1994.

[0025] Examples of modified polyvinyl alcohols include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, etc. Among these, the modified polyvinyl alcohol preferably contains at least one selected from the group consisting of ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol, more preferably contains at least one selected from the group consisting of ethylene-modified polyvinyl alcohol and carboxy-modified polyvinyl alcohol, even more preferably contains ethylene-modified polyvinyl alcohol, and even more preferably is ethylene-modified polyvinyl alcohol.

[0026] As the water-soluble resin, a commercially available product may be used, for example, modified polyvinyl alcohol such as "Exceval (trade name)" manufactured by Kuraray Co., Ltd.

[0027] From the viewpoint of suppressing aggregation of the oxygen barrier layer coating liquid, the water-soluble resin preferably contains polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more but less than 700, and polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more but 2500 or less, and more preferably contains polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more but 500 or less, and polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more but 1200 or less. In the water-soluble resin, the ratio by mass of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more but less than 700 to the mass of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more but less than 2500 (polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more but less than 700:polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 to 2500) is preferably 5:95 to 60:40, more preferably 6:94 to 55:45, even more preferably 7:93 to 40:60, and still more preferably 8:92 to 35:65, from the viewpoint of suppressing aggregation of the oxygen barrier layer coating fluid. In the water-soluble resin, the ratio by mass of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more and 500 or less to the mass of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more and 1200 or less (polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 to 500:polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 to 2500) is preferably 5:95 to 60:40, more preferably 6:94 to 55:45, even more preferably 7:93 to 40:60, and still more preferably 8:92 to 35:65, from the viewpoint of suppressing aggregation of the oxygen barrier layer coating fluid.

[0028] From the viewpoint of suppressing aggregation of the oxygen barrier layer coating liquid, the water-soluble resin preferably contains a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa·s or more and 6 mPa·s or less in a 4% aqueous solution at 20°C, and a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa·s or more and 35 mPa·s or less in a 4% aqueous solution at 20°C, and more preferably contains a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 3 mPa·s or more and 5 mPa·s or less in a 4% aqueous solution at 20°C, and a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa·s or more and 17 mPa·s or less in a 4% aqueous solution at 20°C.

[0029] From the viewpoint of improving oxygen barrier properties and disintegrability, the content of the water-soluble resin in the oxygen barrier layer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, still more preferably 18% by mass or more, based on the solid content of the oxygen barrier layer, and is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less, and still more preferably 35% by mass or less.

[0030] From the viewpoint of improving the oxygen barrier property, the content of polyvinyl alcohol and modified polyvinyl alcohol in the water-soluble resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, of the solid content of the water-soluble resin, and the upper limit thereof is not particularly limited, but is 100% by mass or less.

[0031] (Inorganic Compound) In this embodiment, the inorganic compound has an aspect ratio of 50 or less and an average particle size of 3 μm or less, from the viewpoint of suppressing protrusion from the oxygen barrier layer and improving oxygen barrier properties. From the above viewpoints, the aspect ratio of the inorganic compound is preferably 2 or more, more preferably 5 or more, and preferably 45 or less, more preferably 40 or less, and even more preferably 38 or less. The aspect ratio of the inorganic compound is measured by the method described in the Examples. From the same viewpoints, the average particle size of the inorganic compound is preferably 0.1 μm or more, more preferably 0.2 μm or more, and preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1.2 μm or less. The average particle size of the inorganic compound is measured by the method described in the Examples.

[0032] Examples of the inorganic compound include mica, kaolin, pyrophyllite, talc, bentonite, montmorillonite, vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane, etc. Among these, it is preferable to contain at least one selected from the group consisting of mica, bentonite, kaolin, and talc, it is more preferable to contain at least one selected from the group consisting of mica and kaolin, and it is even more preferable to contain kaolin.

[0033]

[0044] From the viewpoint of improving the oxygen barrier property and water vapor barrier property, the content of the inorganic compound in the oxygen barrier layer is from 150 parts by mass to 540 parts by mass, preferably 160 parts by mass or more, more preferably 170 parts by mass or more, even more preferably 180 parts by mass or more, and preferably 480 parts by mass or less, more preferably 420 parts by mass or less, even more preferably 360 parts by mass or less, and still more preferably 320 parts by mass or less, relative to 100 parts by mass of the water-soluble resin.

[0034] (Layered Inorganic Compound) From the viewpoint of improving oxygen barrier properties, the oxygen barrier layer may further contain a layered inorganic compound having an aspect ratio of preferably 80 or more. The aspect ratio of the layered inorganic compound is more preferably 100 or more, even more preferably 300 or more, still more preferably 500 or more, even more preferably 700 or more, and even more preferably 900 or more. The upper limit is not particularly limited, but is preferably 10,000 or less, more preferably 5,000 or less, even more preferably 3,000 or less, and even more preferably 1,500 or less. When a layered inorganic compound is contained in the oxygen barrier layer, the content of the layered inorganic compound is not particularly limited, but is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, and even more preferably 13 parts by mass or less, relative to 100 parts by mass of the water-soluble resin in the oxygen barrier layer. Examples of layered inorganic compounds include mica, kaolin, pyrophyllite, talc, bentonite, montmorillonite, vermiculite, chlorite, septe chlorite, serpentine, and stilpnomelane. Among these, at least one selected from the group consisting of mica, bentonite, kaolin, and talc is preferred, at least one selected from the group consisting of mica and kaolin is more preferred, and mica is even more preferred. The layered inorganic compound contained in the oxygen barrier layer may be the same type as or different from the inorganic compound contained in the oxygen barrier layer.

[0035] In addition to the water-soluble resin, inorganic compound, and layered inorganic compound, the oxygen barrier layer may contain, as needed, appropriate additives such as pigments, dispersants, surfactants, defoamers, wetting agents, dyes, color adjusters, and thickeners.

[0036] The amount of the oxygen barrier layer applied is preferably 1 g / m2 per side in terms of solid content from the viewpoint of improving the oxygen barrier property. ２ More preferably, 1.5 g / m ２ More preferably, 2.5 g / m ２More preferably, 3.5 g / m ２ When the coating amount exceeds a certain level, the oxygen barrier property reaches a plateau, so from the viewpoint of economy, it is preferably 15 g / m ２ or less, more preferably 13 g / m ２ More preferably, 11 g / m or less ２ More preferably, 7 g / m or less ２ When a paper substrate has a plurality of oxygen barrier layers on one side thereof, the amount of the oxygen barrier layers applied means the total amount of the oxygen barrier layers applied.

[0037] <Water Vapor Barrier Layer> The water vapor barrier layer is a layer having water vapor barrier properties that prevent the transmission of water vapor. The water vapor barrier layer contains a water-dispersible resin.

[0038] (Water-dispersible resin) Water-dispersible resin refers to a resin that is not water-soluble but is finely dispersed in water, such as an emulsion or suspension. Examples of water-dispersible resins include polyolefin resins (polyethylene, polypropylene, etc.), vinyl chloride resins, styrene resins, styrene / butadiene copolymers, styrene / acrylic copolymers, acrylonitrile / styrene copolymers, acrylonitrile / butadiene copolymers, ABS resins, AAS resins, AES resins, vinylidene chloride resins, polyurethane resins, poly-4-methylpentene-1 resins, polybutene-1 resins, vinylidene fluoride resins, vinyl fluoride resins, fluororesins, polycarbonate resins, polyamide resins, acetal resins, polyphenylene oxide resins, polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene sulfide resins, polyimide resins, polysulfone resins, polyethersulfone resins, aromatic polyester resins, polyarylate resins, olefin / unsaturated carboxylic acid copolymers, and modified products thereof. The water-dispersible resin is preferably an emulsion, and more preferably contains at least one selected from the group consisting of a styrene / butadiene copolymer, a styrene / acrylic copolymer, and an olefin / unsaturated carboxylic acid copolymer, and further preferably contains a styrene / acrylic copolymer.

[0039] Styrene / butadiene copolymer Examples of the styrene / butadiene copolymer include styrene / butadiene rubber (SBR) and modified styrene / butadiene rubber (modified SBR). Examples of the modified styrene / butadiene rubber include acid-modified styrene / butadiene rubber (acid-modified SBR). Commercially available styrene / butadiene copolymers may be used, such as "Nipol LX407S series (product name)" and "Nipol LX407BP series (product name)" manufactured by Nippon Zeon Co., Ltd.

[0040] Styrene / Acrylic Copolymer: A styrene / acrylic copolymer is a copolymer obtained by emulsion polymerization of a styrene monomer, an acrylic monomer, and, optionally, other copolymerizable monomers. Examples of styrene monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, p-t-butylstyrene, and chlorostyrene. Examples of acrylic monomers include unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butenetricarboxylic acid; unsaturated polycarboxylic acid alkyl esters having at least one carboxy group such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, and maleic acid monobutyl ester; and (meth)acrylic sulfonic acid monomers or salts thereof such as acrylamidopropanesulfonic acid, acrylate sulfoethyl sodium salt, and methacrylate sulfopropyl sodium salt. Examples of other monomers include (meth)acrylic acid alkyl esters (having 1 to 24 carbon atoms). Styrene is a preferred styrene monomer. Suitable acrylic monomers include acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. Commercially available styrene / acrylic copolymers may be used, such as "Harbil Series C-3 (trade name)" manufactured by Daiichi Toryo Seizosho Co., Ltd., and "ACRONAL 4160 (trade name)" and "Joncryl HPB 4130 (trade name)" manufactured by BASF.

[0041] Olefin / Unsaturated Carboxylic Acid Copolymers Olefin / unsaturated carboxylic acid copolymers are copolymers obtained by emulsion polymerization of an olefin monomer and an unsaturated carboxylic acid monomer. Examples of the olefin monomer in the olefin / unsaturated carboxylic acid copolymer include α-olefins such as ethylene, propylene, and butylene, with ethylene being preferred. The unsaturated carboxylic acid monomer in the olefin / unsaturated carboxylic acid copolymer includes an unsaturated carboxylic acid monomer and an ester monomer of an unsaturated carboxylic acid that forms a carboxylic acid upon hydrolysis. Examples of the unsaturated carboxylic acid monomer in the olefin / unsaturated carboxylic acid copolymer include unsaturated carboxylic acids and their esters, such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butenetricarboxylic acid; and unsaturated polycarboxylic acid alkyl esters having at least one carboxy group, such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, and maleic acid monobutyl ester. The unsaturated carboxylic acid monomers constituting the olefin / unsaturated carboxylic acid copolymer may be used alone or in combination of two or more. The olefin / unsaturated carboxylic acid copolymer may be copolymerized with a small amount of other monomers copolymerizable with the olefin and the unsaturated carboxylic acid monomer. Among these, the olefin / unsaturated carboxylic acid copolymer is preferably at least one selected from the group consisting of ethylene / acrylic acid copolymers and ethylene / methacrylic acid copolymers, more preferably at least one selected from the group consisting of ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, ethylene / methyl acrylate copolymers, ethylene / methyl methacrylate copolymers, ethylene / ethyl acrylate copolymers, ethylene / ethyl methacrylate copolymers, ethylene / butyl acrylate copolymers, and ethylene / butyl methacrylate copolymers, and even more preferably an ethylene / acrylic acid copolymer.

[0042] A commercially available product may be used as the olefin / unsaturated carboxylic acid copolymer, for example, "Zaixen (trade name) AC" manufactured by Sumitomo Seika Chemicals Co., Ltd., which is an aqueous dispersion of ethylene / acrylic acid copolymer ammonium salt.

[0043] The olefin / unsaturated carboxylic acid copolymer has an unsaturated carboxylic acid monomer unit content of preferably 1 mol % or more, more preferably 10 mol % or more, and preferably 50 mol % or less, more preferably 30 mol % or less.

[0044]

[0044] The content of the water-dispersible resin is not particularly limited, but is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and still more preferably 70% by mass or more, of the total solid content of the water vapor barrier layer.

[0045] From the viewpoint of imparting slip properties and suppressing blocking, it is preferable that the water vapor barrier layer further contains a wax. Examples of waxes include natural waxes such as animal- or plant-derived waxes (e.g., beeswax, carnauba wax, etc.), mineral waxes (e.g., microcrystalline wax, etc.), and petroleum wax; and synthetic waxes such as polyolefin wax, paraffin wax, and polyester wax. Among these, it is preferable that the water vapor barrier layer contains at least one wax selected from the group consisting of paraffin wax, carnauba wax, and polyolefin wax, and it is more preferable that the water vapor barrier layer contains paraffin wax.

[0046] The content of the wax in the water vapor barrier layer is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, of the total solid content of the water vapor barrier layer.

[0047] In addition to the water-dispersible resin and wax, the water vapor barrier layer may contain appropriate additives such as dispersants, surfactants, antifoaming agents, wetting agents, dyes, color adjusters, and thickeners, as needed.

[0048] The amount of the water vapor barrier layer applied is preferably 1 g / m2 per side in terms of solid content. ２More preferably, 3 g / m ２ More preferably, 4 g / m ２ and preferably 15 g / m ２ or less, more preferably 10 g / m ２ More preferably, 8 g / m or less ２ When a paper substrate has multiple water vapor barrier layers on one side, the amount of water vapor barrier layers applied refers to the total amount applied.

[0049] <Optional Layer> The gas barrier laminate may include an optional layer in addition to the paper substrate, oxygen barrier layer, and water vapor barrier layer. An example of the optional layer is a printed layer. When the optional layer includes a printed layer, it is preferable to provide the printed layer on the side of the paper substrate opposite to the side on which the oxygen barrier layer and water vapor barrier layer are provided. The printed layer preferably contains a pigment and a binder.

[0050] [Method for manufacturing gas barrier laminate] The method for manufacturing the gas barrier laminate according to this embodiment preferably includes the step of laminating an oxygen barrier layer and a water vapor barrier layer on at least one surface of a paper base material, and more preferably carries out the step of laminating an oxygen barrier layer on at least one surface of the paper base material, followed by the step of laminating a water vapor barrier layer on the oxygen barrier layer (paper base material / oxygen barrier layer / water vapor barrier layer, paper base material / oxygen barrier layer / water vapor barrier layer / oxygen barrier layer / water vapor barrier layer..., paper base material / oxygen barrier layer / oxygen barrier layer... / water vapor barrier layer / water vapor barrier layer...).

[0051] The oxygen barrier layer may be formed by applying a coating liquid containing the components constituting the oxygen barrier layer described above to at least one surface of the paper substrate, by melt-extrusion laminating the components, or by preparing a film containing the components and laminating it with an adhesive, etc. Among these, it is preferable that the oxygen barrier layer is laminated by applying a coating liquid containing the components constituting the oxygen barrier layer described above.

[0052] The solvent for the coating liquid is not particularly limited, and water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone, or toluene can be used. Among these, water is preferred as the dispersion medium for the coating liquid, from the viewpoint of avoiding the problems of volatile organic solvents. The solids content of the coating liquid is not particularly limited, and may be appropriately selected from the viewpoints of coatability and ease of drying. It is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The coating equipment for applying the coating liquid is not particularly limited, and known equipment can be used. Examples of coating equipment include blade coaters, bar coaters, air knife coaters, slit die coaters, gravure coaters, microgravure coaters, and gate roll coaters. The drying equipment for drying the applied coating liquid is not particularly limited, and known equipment can be used. Examples of drying equipment include hot air dryers, infrared dryers, and hot plates. The drying temperature may be appropriately set taking into consideration the drying time, etc.

[0053] From the viewpoint of suppressing aggregation of the oxygen barrier layer coating liquid, the water-soluble resin constituting the coating liquid preferably contains a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa s or more and 6 mPa s or less in a 4% aqueous solution at 20°C, and a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 35 mPa s or less in a 4% aqueous solution at 20°C, and more preferably contains a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 3 mPa s or more and 5 mPa s or less in a 4% aqueous solution at 20°C, and a polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 17 mPa s or less in a 4% aqueous solution at 20°C.

[0054] In the water-soluble resins constituting the coating liquid, the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa s or more and 6 mPa s or less in a 4% aqueous solution at 20°C to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 35 mPa s or less in a 4% aqueous solution at 20°C (polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 to 6 mPa s:polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 to 35 mPa s) is preferably 5:95 to 60:40, more preferably 6:94 to 55:45, even more preferably 7:93 to 40:60, and still more preferably 8:92 to 35:65, from the viewpoint of suppressing aggregation of the oxygen barrier layer coating liquid. In the water-soluble resins constituting the coating liquid, the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 3 mPa s or more and 5 mPa s or less in a 4% aqueous solution at 20°C to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 17 mPa s or less in a 4% aqueous solution at 20°C (polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 3 to 5 mPa s:polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 to 17 mPa s) is preferably 5:95 to 60:40, more preferably 6:94 to 55:45, even more preferably 7:93 to 40:60, and still more preferably 8:92 to 35:65, from the viewpoint of suppressing aggregation of the oxygen barrier layer coating liquid.

[0055] The water vapor barrier layer may be formed by applying a coating liquid containing the components constituting the water vapor barrier layer described above, by melt-extrusion laminating the components, or by preparing a film containing the components and laminating it with an adhesive or the like. Among these, the water vapor barrier layer is preferably laminated by applying a coating liquid containing the components constituting the water vapor barrier layer described above. The solvent, solids content, coating equipment, and drying equipment for the coating liquid can be appropriately selected in the same manner as for the coating liquid for the oxygen barrier layer.

[0056] The gas barrier laminate may have the above-mentioned optional layers laminated thereon in addition to the paper substrate, oxygen barrier layer, and water vapor barrier layer. The optional layers can be formed by known methods.

[0057] <Characteristics of Gas Barrier Laminate> (Water Vapor Permeability) The lower the water vapor permeability of the gas barrier laminate, the less water vapor is transmitted, which is preferable. Specifically, it is preferably 20 g / (m ２ ·day) or less, more preferably 18 g / (m ２ ·day) or less, more preferably 16 g / (m ２ ·day) or less, and even more preferably 13 g / (m ２ ·day) or less, more preferably 11 g / (m ２ ·day) or less, and more preferably 9 g / (m ２ The water vapor permeability of the gas barrier laminate is measured by the method described in the examples.

[0058] (Oxygen Permeability) The lower the oxygen permeability of the gas barrier laminate, the less oxygen is permeated, and specifically, it is preferably 35 mL / (m ２ ·day·atm) or less, more preferably 30 mL / (m ２ ·day·atm) or less, more preferably 25 mL / (m ２ ·day·atm) or less, and even more preferably 17 mL / (m ２ ·day·atm) or less, more preferably 13 mL / (m ２ ·day·atm) or less, and more preferably 10 mL / (m ２ ·day·atm) or less, and even more preferably 6 mL / (m ２ The oxygen permeability of the gas barrier laminate is measured by the method described in the examples.

[0059]

[0043] (Heat seal peel strength) When the water vapor barrier layers of the gas barrier laminate are heat-sealed together under conditions of 160°C, 0.2 MPa, and 1 second, the heat seal peel strength is, from the viewpoint of heat sealability and ease of production, preferably 1 N / 15 mm or more, more preferably 2 N / 15 mm or more, and preferably 15 N / 15 mm or less, more preferably 10 N / 15 mm or less, and even more preferably 7 N / 15 mm or less. The heat seal peel strength of the gas barrier laminate is measured by the method described in the examples.

[0060] (Disintegration Rate) From the viewpoint of improving recyclability, the disintegration rate of the gas barrier laminate is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. The disintegration rate of the gas barrier laminate is measured by the method described in the examples.

[0061] The gas barrier laminate of this embodiment takes advantage of its excellent oxygen barrier property, water vapor barrier property and disintegrability, and is therefore suitable as a packaging material for foods, fruits, medical products, electronic components, etc. Also provided is a packaging bag made using the gas barrier laminate of this embodiment.

[0062] [Packaging Bag] A packaging bag according to another embodiment of the present disclosure is a packaging bag made using the gas barrier laminate. Examples of packaging bags include standing pouch, side seal, two-sided seal, three-sided seal, four-sided seal, envelope seal, grommed seal (pillow seal), pleated seal, flat bottom seal, square bottom seal, and gusset seal. The packaging bag of this embodiment may be formed by folding the gas barrier laminate or overlapping two sheets and bonding their peripheral edges with an adhesive to achieve the above-mentioned shape, but is preferably formed by folding the water vapor barrier layer of the gas barrier laminate or overlapping two sheets so that the water vapor barrier layers face each other and heat-sealing their peripheral edges to achieve the above-mentioned shape.

[0063] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. In the examples and comparative examples, "parts" and "%" refer to "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0064] [Analysis and Evaluation] The inorganic compounds, water-soluble resins, layered inorganic compounds, and oxygen barrier layer coating solutions used in the Examples and Comparative Examples were analyzed as follows. In addition, the gas barrier laminates of the Examples and Comparative Examples were evaluated as follows.

[0065] <Inorganic Compound and / or Layered Inorganic Compound> (Aspect Ratio) The aspect ratios of the inorganic compound and layered inorganic compound were determined from enlarged photographs taken with an electron microscope. Specifically, an enlarged photograph of the cross section of a laminate containing an inorganic compound and / or layered inorganic compound was taken with an electron microscope at a magnification such that approximately 20 to 50 pigment particles were included within the image, and the length and thickness of each pigment particle within the image were measured to calculate the aspect ratio. The average of the obtained aspect ratios was calculated to be the aspect ratio of the inorganic compound and layered inorganic compound.

[0066] (Average particle size) The average particle size of the inorganic compound was determined as the particle size (D50) at which the integrated value becomes 50% in the volume-based particle size distribution using a laser diffraction / scattering particle size distribution analyzer (manufactured by Microtrac Bell Corporation, product name: Microtrac MT3300EXII).

[0067] <Water-soluble Resin> (Saponification Degree) The saponification degree of the water-soluble resin was measured in accordance with JIS K 6726:1994.

[0068] (Viscosity Average Degree of Polymerization) The viscosity average degree of polymerization of the water-soluble resin was measured in accordance with JIS K 6726:1994.

[0069] <Oxygen Barrier Layer Coating Fluid> (Aggregate Ratio) The aggregate ratio of the oxygen barrier layer coating fluid was measured using a Marlon stability tester (manufactured by SMT Corporation, product name: PM-9302MT) using a coating fluid adjusted to a solids concentration of 10 mass %. Specifically, 50 g of the coating fluid (as is) was rotated at 1,000 rpm for 20 minutes in the Marlon stability tester under a load of 15 kg, and the generated aggregates were filtered through a 200-mesh stainless steel wire screen, washed with water, recovered, dried in a dryer at 105°C for 30 minutes, and then their mass was measured, and the ratio of aggregates to the solids contained in 50 g of the coating fluid (as is) was calculated.

[0070] <Gas Barrier Laminate> (Water Vapor Permeability) The water vapor permeability of the gas barrier laminate was measured in accordance with JIS Z 0208:1976 (cup method), Method B (temperature 40±0.5°C, relative humidity 90±2%), with the water vapor barrier layer of the gas barrier laminate facing inward.

[0071] (Oxygen Permeability) The oxygen permeability of the gas barrier laminate was measured using an oxygen permeability measuring device (manufactured by MOCON Corporation, trade name: OX-TRAN2 / 22) under conditions of 23°C and 50% RH. Specifically, an isocyanate-based adhesive (a mixture of 10 parts of "Dicdry LX-500 (trade name)" and 1 part of "Dicdry KW-75 (trade name)" manufactured by DIC Corporation) was applied to the surface of the water vapor barrier layer of the gas barrier laminate at a solid content of 4 g / m. ２ After application, the coating was dried for 10 seconds in a blower dryer set at 80°C, and a 20 μm thick unstretched polypropylene film (manufactured by Hokuetsu Chemicals Co., Ltd., product name: GP-32) was laminated to form a laminate sheet. The oxygen permeability of the laminate sheet was measured at 23°C and 50% RH in accordance with JIS K 7126-2:2006. The lower the oxygen permeability value, the better the oxygen barrier property. The unstretched polypropylene film was laminated to facilitate measurement without being affected by the unevenness of the laminate, and the unstretched polypropylene film does not affect the oxygen permeability.

[0072] (Heat seal peel strength) Two gas barrier laminates were stacked together with the water vapor barrier layers facing each other, and heat-sealed using a heat seal tester (manufactured by Tester Sangyo Co., Ltd., product name: TP-701-B) at 160°C, 0.2 MPa, and for 1 second. The heat-sealed test piece was left to stand for 4 hours or more in a room at a temperature of 23°C±1°C and a relative humidity of 50%±2%. Subsequently, the heat-sealed test piece was cut to a width of 15 mm and T-peeled using a tensile tester at a tensile speed of 300 mm / min, and the recorded maximum load was taken as the heat seal peel strength.

[0073] (Disaggregation Rate) A gas barrier laminate having an oven-dry mass of 50 g was cut into approximately 3 cm squares, diluted with warm water at 40°C so that the concentration of the gas barrier laminate became 2.5%, and disaggregated for 10 minutes at 3,000 rpm using a TAPPI standard disaggregator (manufactured by Kumagaya Riki Co., Ltd.). The resulting pulp slurry was passed through a flat screen (manufactured by Kumagaya Riki Co., Ltd.) equipped with a 6-cut (slit width: 0.15 mm) screen plate, and refined in a water flow of 8.6 L / min. The undisaggregated material remaining on the screen plate was collected and dried in an oven at 105°C. The mass was measured, and the disaggregation rate was calculated using the following formula: Disaggregation rate (%) = {Oven-dry mass (g) of the gas barrier laminate used for the test - Oven-dry mass (g) of the undisaggregated material} / Oven-dry mass (g) of the gas barrier laminate used for the test × 100

[0074] Example 1 <Preparation of Oxygen Barrier Layer Coating Fluid> An oxygen barrier layer coating fluid was prepared by adding 200 parts by mass (solids content) of an aqueous dispersion of kaolin (Contour Xtreme (product name), manufactured by Shiraishi Kogyo Co., Ltd., particle size: 0.9 μm, aspect ratio: approximately 33) having a solids content of 50% to 100 parts by mass (solids content) of a 10% solids content aqueous solution of ethylene-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., "EXCEVAL HR-3010 (product name)", degree of saponification: 99%, viscosity-average degree of polymerization: 1,000, viscosity (20°C, 4% aqueous solution): 12.0-16.0 mPa s (catalog value)), and further adding water to adjust the solids content to 10% by mass, followed by stirring. <Preparation of Water Vapor Barrier Layer Coating Liquid> A water vapor barrier layer coating liquid was prepared by adding water to 100 parts by mass (solid content) of a paraffin-containing styrene acrylic aqueous dispersion ("Joncryl HPB4130 (trade name)" manufactured by BASF Japan Ltd., solid content concentration 42%) so that the solid content concentration was 30% by mass, and stirring the mixture. <Preparation of Gas Barrier Laminate> The obtained oxygen barrier layer coating liquid was applied to a gas barrier laminate having a basis weight of 50 g / m. ２ , 4 g / m solids on the rough side of 66 μm thick one-sided gloss bleached kraft paper (manufactured by Oji Materia Co., Ltd., CSF after disintegration: 400 mL) ２ The resulting water vapor barrier layer coating liquid was applied to the oxygen barrier layer in a solid content of 6 g / m2 using a bar coater, and then dried for 20 seconds using a blower dryer set at 140°C to form an oxygen barrier layer. ２ The coating was applied using a bar coater so that the coating became as shown in Table 1, and the coating was dried for 20 seconds using a fan dryer set at 140° C. to form a water vapor barrier layer, thereby obtaining a gas barrier laminate. The measurement results are shown in Table 1.

[0075] Examples 2 and 8 Gas barrier laminates were obtained in the same manner as in Example 1, except that in preparing the oxygen barrier layer coating solution, the amount of kaolin added was set to the value shown in Table 1. The measurement results are shown in Table 1.

[0076] Example 3 A gas barrier laminate was obtained in the same manner as in Example 1, except that in the preparation of the oxygen barrier layer coating solution, the amount of kaolin added was the value shown in Table 1, and the amount of the oxygen barrier layer applied was the value shown in Table 1. The measurement results are shown in Table 1.

[0077] Examples 4 to 7 Gas barrier laminates were obtained in the same manner as in Example 3, except that the amount of the oxygen barrier layer applied was set to the values ​​shown in Table 1. The measurement results are shown in Table 1.

[0078] Example 9 A gas barrier laminate was obtained in the same manner as in Example 7, except that the ethylene-modified polyvinyl alcohol used in preparing the oxygen barrier layer coating solution was changed to "EXCEVAL AQ-4104 (product name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 400, viscosity (20°C, 4% aqueous solution): 3.5-4.5 mPa s (catalog value)). The measurement results are shown in Table 1.

[0079] Example 10 A gas barrier laminate was obtained in the same manner as in Example 2, except that the kaolin used in preparing the oxygen barrier layer coating solution was changed to "Kaofine 90 (product name)" (manufactured by Shiraishi Kogyo Co., Ltd., particle size: 0.3 μm, aspect ratio: approximately 10). The measurement results are shown in Table 1.

[0080] Example 11 A gas barrier laminate was obtained in the same manner as in Example 2, except that in preparing the oxygen barrier layer coating solution, 10 parts by mass (solid content) of an aqueous dispersion of synthetic mica (manufactured by Topy Industries, Ltd., "NTS-10NC (trade name)", particle size: 19.8 μm, aspect ratio: approximately 1260) dispersed in water and having a solid content concentration of 8% was further added. The measurement results are shown in Table 1.

[0081] Example 12 A gas barrier laminate was obtained in the same manner as in Example 11, except that in preparing the oxygen barrier layer coating solution, the amount of synthetic mica added was set to the value shown in Table 1. The measurement results are shown in Table 1.

[0082] Example 13 A gas barrier laminate was obtained in the same manner as in Example 1, except that in the preparation of the oxygen barrier layer coating solution, the ethylene-modified polyvinyl alcohol was changed to 10 parts by mass (solids content) of a 10% solids aqueous solution of "EXCEVAL AQ-4104 (trade name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 400, viscosity (20°C, 4% aqueous solution): 3.5-4.5 mPa s (catalog value)), and 90 parts by mass (solids content) of a 10% solids aqueous solution of "EXCEVAL HR-3010 (trade name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 1,000, viscosity (20°C, 4% aqueous solution): 12.0-16.0 mPa s (catalog value)). The measurement results are shown in Table 2.

[0083] Examples 14 and 15 Gas barrier laminates were obtained in the same manner as in Example 13, except that the blending amount (solid content) of a 10% solids aqueous solution of "EXCEVAL AQ-4104 (trade name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 400, viscosity (20°C, 4% aqueous solution): 3.5-4.5 mPa s (catalog value)) used in the preparation of the oxygen barrier layer coating solution and the blending amount (solid content) of a 10% solids aqueous solution of ethylene-modified polyvinyl alcohol "EXCEVAL HR-3010 (trade name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 1,000, viscosity (20°C, 4% aqueous solution): 12.0-16.0 mPa s (catalog value)) used in the preparation of the oxygen barrier layer coating solution were the values ​​shown in Table 2. The measurement results are shown in Table 2.

[0084] Example 16 A gas barrier laminate was obtained in the same manner as in Example 1, except that the ethylene-modified polyvinyl alcohol used in preparing the oxygen barrier layer coating solution was changed to 100 parts by mass of "EXCEVAL AQ-4104 (product name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 99%, viscosity-average degree of polymerization: 400, viscosity (20°C, 4% aqueous solution): 3.5-4.5 mPa s (catalog value)). The measurement results are shown in Table 2.

[0085] Comparative Examples 1 and 2 Gas barrier laminates were obtained in the same manner as in Example 1, except that in the preparation of the oxygen barrier layer coating solution, the amount of kaolin added was changed to the value shown in Table 3. The measurement results are shown in Table 3.

[0086] Comparative Example 3 A gas barrier laminate was obtained in the same manner as in Example 5, except that the kaolin used in preparing the oxygen barrier layer coating solution was changed to "Barisurf HX (product name)" (manufactured by Shiraishi Kogyo Co., Ltd., particle size: 9 μm, aspect ratio: approximately 100). The measurement results are shown in Table 3.

[0087] Comparative Example 4 A gas barrier laminate was obtained in the same manner as in Example 5, except that the polyvinyl alcohol used in preparing the oxygen barrier layer coating solution was changed to "PVA-217 (trade name)" (manufactured by Kuraray Co., Ltd., degree of saponification: 88%, viscosity-average degree of polymerization: 1,700, viscosity (20°C, 4% aqueous solution): 20.5-24.5 mPa s (catalog value)). The measurement results are shown in Table 3.

[0088] Comparative Example 5 A gas barrier laminate was obtained in the same manner as in Example 1, except that in preparing the oxygen barrier layer coating solution, water was added to 100 parts by mass (solid content) of a polyurethane dispersion ("Takelac WPB-341" manufactured by Mitsui Chemicals, Inc., solid content concentration 30%) so that the solid content concentration was 25% by mass, and the mixture was stirred. The measurement results are shown in Table 3.

[0089]

[0090]

[0091]

[0092] As can be seen from Tables 1 and 2, the present invention provides a gas barrier laminate that is excellent in oxygen barrier property, water vapor barrier property, and disintegration property.

Claims

A gas barrier laminate comprising a paper substrate and an oxygen barrier layer and a water vapor barrier layer in this order on at least one surface of the paper substrate, the oxygen barrier layer contains a water-soluble resin and an inorganic compound having an aspect ratio of 50 or less and an average particle size of 3 μm or less, the water-soluble resin contains at least one resin selected from the group consisting of polyvinyl alcohol and modified polyvinyl alcohol, each having a saponification degree of 93% or more; the content of the inorganic compound is 150 parts by mass or more and 540 parts by mass or less relative to 100 parts by mass of the water-soluble resin, the water vapor barrier layer contains a water-dispersible resin, Gas barrier laminate.

2. The gas barrier laminate according to claim 1, wherein the water-soluble resin comprises a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more and less than 700, and a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more and 2500 or less.

3. The gas barrier laminate according to claim 2, wherein the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 100 or more and less than 700 to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 700 or more and 2500 or less, in the water-soluble resin, is 5:95 to 60:

40.

2. The gas barrier laminate according to claim 1, wherein the water-soluble resin comprises a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more and 500 or less, and a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more and 1200 or less.

5. The gas barrier laminate according to claim 4, wherein the ratio of the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 300 or more and 500 or less to the content of polyvinyl alcohol or modified polyvinyl alcohol having a viscosity-average degree of polymerization of 900 or more and 1200 or less, in the water-soluble resin, is 5:95 to 60:

40.

6. The gas barrier laminate according to claim 1, wherein the oxygen barrier layer further contains a layered inorganic compound having an aspect ratio of 80 or more, and the content of the layered inorganic compound is 25 parts by mass or less per 100 parts by mass of the water-soluble resin.

6. The gas barrier laminate according to claim 1, wherein the inorganic compound contains kaolin.

6. The gas barrier laminate according to claim 1, wherein the water-dispersible resin contains a styrene / acrylic copolymer. 　 The gas barrier laminate according to any one of claims 1 to 5, wherein the water vapor barrier layer further contains a wax. 　 The gas barrier laminate according to claim 9 , wherein the wax comprises paraffin wax. 　 The amount of the oxygen barrier layer applied is 1 g / m ２ 15g / m or more ２ The gas barrier laminate according to any one of claims 1 to 5, wherein: 　 The amount of the water vapor barrier layer applied is 4 g / m ２ 8g / m or more ２ The gas barrier laminate according to any one of claims 1 to 5, wherein: Water vapor permeability is 20 g / (m ２ 6. The gas barrier laminate according to claim 1, wherein the average temperature is 100°C or less. Oxygen permeability is 30 mL / (m ２ 6. The gas barrier laminate according to claim 1, wherein the gas barrier density is 1000 kJ / s or less. The gas barrier laminate according to any one of claims 1 to 5, which is used as a packaging material. 　 A packaging bag made using the gas barrier laminate according to any one of claims 1 to 5. 　 A method for producing the gas barrier laminate according to any one of claims 1 to 5, comprising the steps of: The method includes a step of laminating an oxygen barrier layer and a water vapor barrier layer on at least one surface of the paper substrate, a water-soluble resin containing a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity of 2 mPa·s or more and 6 mPa·s or less in a 4% aqueous solution at 20°C, and a polyvinyl alcohol or a modified polyvinyl alcohol having a viscosity of 11 mPa·s or more and 35 mPa·s or less in a 4% aqueous solution at 20°C.

18. The method for producing a gas barrier laminate according to claim 17, wherein the ratio of the content of the polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 2 mPa s or more and 6 mPa s or less as a 4% aqueous solution at 20°C to the content of the polyvinyl alcohol or modified polyvinyl alcohol having a viscosity of 11 mPa s or more and 35 mPa s or less as a 4% aqueous solution at 20°C is 5:95 to 60:40.

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