Gas barrier film, laminate and packaging bag

Abstract

A gas barrier film according to one aspect of the present disclosure comprises: a substrate film that contains polypropylene; and a vapor deposition layer that contains an inorganic oxide and that is disposed on a first surface, which is one surface of the substrate film, wherein the substrate film is provided with a second skin layer that has a second surface, which is the surface on the opposite side from the first surface of the substrate film, and a core layer. The second skin layer contains 1500-4000 mass ppm of silicon-containing particles.

Description

[Technical Field]

[0001] The present disclosure relates to a gas barrier film, a laminate, and a packaging bag. [Background technology]

[0002] Packaging materials such as packaging bags used for packaging foods, beverages, pharmaceuticals, etc. are required to have gas barrier properties that prevent the intrusion of gases such as oxygen that cause deterioration of the contents, in order to prevent deterioration and spoilage of the contents and maintain their functionality and quality. For this reason, films with gas barrier properties (gas barrier films) have traditionally been used for these packaging materials.

[0003] Known examples of such gas barrier films include a substrate containing a thermoplastic resin, a metal oxide layer, and a gas barrier coating layer in this order, in which the ratio of silicon atoms to carbon atoms (Si / C) on the surface of the gas barrier coating layer, as measured by X-ray photoelectron spectroscopy, is greater than 0 and less than 0.50 (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-50299 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the gas barrier film described in Patent Document 1, when contents are placed in a packaging bag and subjected to retort treatment, the flavor of the contents may deteriorate, and in this respect there is room for improvement.

[0006] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a gas barrier film that can suppress flavor deterioration of the contents after retort treatment and that can maintain good oxygen barrier properties even after retort treatment, as well as a laminate and a packaging bag using the same. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides the following gas barrier film, laminate, and packaging bag. [1] A gas barrier film comprising a base film containing polypropylene and a vapor-deposited layer containing an inorganic oxide disposed on a first surface, which is one surface of the base film, wherein the base film comprises a second skin layer having a second surface, which is the surface of the base film opposite to the first surface, and a core layer, and the second skin layer contains silicon-containing particles in a proportion of 1500 ppm by mass or more and 4000 ppm by mass or less. [2] The gas barrier film according to [1] above, wherein the second skin layer further contains an antiblocking agent other than the silicon-containing particles. [3] The gas barrier film according to [1] or [2] above, wherein the silicon-containing particles have an average particle size of 1 μm or more and 6 μm or less. [4] The gas barrier film according to any one of the above [1] to [3], wherein the base film comprises a first skin layer having the first surface. [5] The gas barrier film according to [4], wherein the first skin layer contains a copolymer of propylene and an α-olefin, and the arithmetic mean height Sa1 of the first surface of the base film is 30 nm or more and 80 nm or less, and the arithmetic mean height Sa2 of the second surface is 40 nm or more and 120 nm or less. [6] The gas barrier film according to the above [5], wherein the value of Sa1+Sa2 is 80 nm or more and 150 nm or less. [7] The gas barrier film according to [5] or [6] above, wherein the first skin layer contains an antiblocking agent. [8] The gas barrier film according to any one of the above [1] to [7], wherein the vapor-deposited layer contains aluminum oxide or silicon oxide. [9] The gas barrier film according to any one of the above [1] to [8], further comprising a gas barrier coating layer disposed on the surface of the vapor deposition layer opposite to the substrate film.

[10] The gas barrier film according to any one of the above [1] to [9], further comprising an anchor coat layer disposed between the substrate film and the vapor deposition layer.

[11] A laminate comprising the gas barrier film according to any one of the above [1] to

[10] and a sealant layer disposed on the second skin layer side of the gas barrier film.

[12] The laminate according to

[11] above, further comprising a resin film containing polypropylene arranged on the opposite side of the gas barrier film from the sealant layer.

[13] A packaging bag produced by producing the laminate described in

[11] or

[12] above. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a gas barrier film that can suppress flavor deterioration of the contents after retort processing and that can maintain good oxygen barrier properties even after retort processing, as well as a laminate and a packaging bag using the same. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a substrate film according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic cross-sectional view showing a gas barrier film according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a schematic cross-sectional view showing a laminate according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a schematic cross-sectional view showing a laminate according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail, with reference to the drawings as needed. However, the present disclosure is not limited to the following embodiments.

[0011] <Base film> The substrate film is a film (base film) that serves as a support in the gas barrier film and contains polypropylene. The substrate film has a vapor-deposited layer containing an inorganic oxide formed on one surface, a first surface. The substrate film includes a core layer and a second skin layer having a second surface, which is the surface opposite to the first surface, and the second skin layer contains silicon-containing particles in a proportion of 1500 ppm by mass or more and 4000 ppm by mass or less. The substrate film may further include a first skin layer having the first surface.

[0012] A gas barrier film having a vapor deposition layer formed on the first surface of the above-mentioned base film has a second skin layer that satisfies the above-mentioned conditions, and thereby can suppress deterioration of the flavor of the contents after retort processing and can maintain good oxygen barrier properties even after retort processing.

[0013] Fig. 1 is a schematic cross-sectional view showing a substrate film according to one embodiment. The substrate film shown in Fig. 1 has a three-layer structure consisting of a first skin layer 11 having a first surface F1, a core layer 12, and a second skin layer 13 having a second surface F2. The substrate film may have a two-layer structure consisting of the second skin layer 13 and the core layer 12, or may have a multi-layer structure of four or more layers further including layers other than the first skin layer 11, the core layer 12, and the second skin layer 13.

[0014] (Second skin layer) The second skin layer 13 contains silicon-containing particles. Examples of the silicon-containing particles include silica particles and silicate particles. Examples of the silicate particles include aluminum silicate and calcium silicate. The silicon-containing particles may be an antiblocking agent. The shape of the silicon-containing particles is not particularly limited, but they are preferably spherical or approximately spherical in shape so as to prevent scratches on the first skin layer 11 that comes into contact with the silicon-containing particles during winding. One type of silicon-containing particle may be used alone, or two or more types may be used in combination.

[0015] The second skin layer 13 preferably contains polypropylene. The second skin layer 13 may contain homopolypropylene or a copolymer of propylene and another monomer.

[0016] Other monomers used in the copolymer may include, for example, α-olefins such as ethylene, 1-butene, and 1-hexene. Second skin layer 13 may contain a copolymer of propylene and an α-olefin. The copolymer may be a random copolymer. The melting point of the resin used in second skin layer 13 may be 130 to 150°C.

[0017] The content of propylene units in the copolymer may be 80 mol% or more, 90 mol% or more, 95 mol% or more, or 96 mol% or more, or may be 99.7 mol% or less, 99.5 mol% or less, 99 mol% or less, or 98 mol% or less, based on the total amount of monomer units.

[0018] The polypropylene used in second skin layer 13 may be a resin polymerized from fossil fuel, a recycled resin, or a resin obtained by polymerizing raw materials derived from biomass such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuel and a recycled resin or a resin obtained by polymerizing raw materials derived from biomass such as plants.

[0019] The second skin layer 13 contains silicon-containing particles at a ratio of 1500 to 4000 ppm by mass. When the content of silicon-containing particles in the second skin layer 13 is 1500 ppm by mass or more, the silicon-containing particles can provide good anti-blocking and odor adsorption effects. This can prevent flavor deterioration of the contents even when the contents are placed in a packaging bag and subjected to retort treatment. On the other hand, when the content of silicon-containing particles in the second skin layer 13 is 4000 ppm by mass or less, this can prevent the silicon-containing particles from falling off or scratches caused by the silicon-containing particles during production of the gas barrier film. This can prevent deterioration of the oxygen barrier property of the gas barrier film, allowing the gas barrier film to maintain good oxygen barrier property even after retort treatment. From the viewpoint of more fully achieving the above effects, the content of silicon-containing particles in the second skin layer 13 is preferably 1500 to 3500 ppm by mass, more preferably 2000 to 3500 ppm by mass.

[0020] The average particle diameter of the silicon-containing particles is preferably 1 to 6 μm. In this specification, the average particle diameter is the weight-average diameter measured by the coal tar method. When the average particle diameter of the silicon-containing particles is 1 μm or more, the silicon-containing particles can provide good anti-blocking and odor adsorption effects. This can prevent flavor deterioration of the contents even when the contents are placed in a packaging bag and subjected to retort treatment. On the other hand, when the average particle diameter of the silicon-containing particles is 6 μm or less, it can prevent the silicon-containing particles from falling off or from causing scratches during the production of the gas barrier film. This can prevent deterioration of the oxygen barrier property of the gas barrier film, allowing the gas barrier film to maintain good oxygen barrier property even after retort treatment. From the viewpoint of more fully achieving the above effects, the average particle diameter of the silicon-containing particles is more preferably 2 to 5 μm.

[0021] The second skin layer 13 may contain an antiblocking agent (hereinafter also referred to as "AB agent") other than silicon-containing particles. The other AB agent may be organic particles or inorganic particles. Examples of organic particles include acrylic resin particles, polymethyl methacrylate particles, polystyrene particles, and polyamide particles. Among these, it is preferable to use acrylic resin particles or polymethyl methacrylate particles from the viewpoint of minimizing damage to the resin surface layer by the particles. Any one of these AB agents may be used alone, or two or more may be used in combination.

[0022] The average particle size of the organic particles is preferably 1 to 6 μm. When the average particle size of the organic particles is 1 μm or more, a good anti-blocking effect can be obtained by the organic particles. On the other hand, when the average particle size of the organic particles is 6 μm or less, it is possible to prevent the organic particles from falling off or from causing scratches during the production of the gas barrier film. This makes it possible to prevent deterioration of the oxygen barrier property of the gas barrier film, and the gas barrier film can maintain good oxygen barrier property even after retort treatment. From the viewpoint of more fully obtaining the above effects, it is more preferable that the average particle size of the organic particles is 2 to 5 μm.

[0023] When the second skin layer 13 contains another AB agent, the content thereof is preferably an amount such that the total content of the silicon-containing particles and the other AB agent is 2000 to 4500 ppm by mass, 2000 to 4000 ppm by mass, or 2500 to 4000 ppm by mass. When the content of the other AB agent is within the above range, the anti-blocking performance can be further improved without impairing the effects of the present disclosure.

[0024] The second skin layer 13 may contain, for example, an antioxidant, a stabilizer, a lubricant, an antistatic agent, and the like.

[0025] From the viewpoint of enabling uniform film formation, the thickness of second skin layer 13 is preferably 0.1 to 2.0 μm, and more preferably 0.3 to 1.5 μm.

[0026] (First skin layer) The first skin layer 11 preferably contains polypropylene. The first skin layer 11 may contain homopolypropylene or a copolymer of propylene and another monomer. The polypropylene may be the same as that used for the second skin layer 13. By providing the base film 1 with the first skin layer 11, stress applied to the vapor-deposited layer due to shrinkage of the base film 1 after heat sterilization can be alleviated, and damage to the vapor-deposited layer can be suppressed.

[0027] The first skin layer 11 may contain a copolymer of propylene and an α-olefin. This improves the adhesion between the first skin layer 11 and the core layer 12, and between the first skin layer 11 and the vapor-deposited layer. Examples of the α-olefin include ethylene, 1-butene, and 1-hexene. The α-olefin may be used alone or in combination of two or more. The copolymer may be a random copolymer. The melting point of the resin used in the first skin layer 11 may be 130 to 150°C.

[0028] The polypropylene used in first skin layer 11 may be a resin polymerized from fossil fuel, a recycled resin, or a resin obtained by polymerizing raw materials derived from biomass such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuel and a recycled resin or a resin obtained by polymerizing raw materials derived from biomass such as plants.

[0029] The first skin layer 11 may or may not contain an AB agent. When an outer layer film such as a second base film described below is laminated on the first skin layer 11 side of the gas barrier film, the adhesion between the gas barrier film and the outer layer film can be improved by having the first skin layer 11 contain an AB agent. The AB agent may be silicon-containing particles or other AB agents. The other AB agents may be organic particles or inorganic particles. Examples of organic particles include acrylic resin particles, polymethyl methacrylate particles, polystyrene particles, and polyamide particles. Among these, it is preferable to use acrylic resin particles or polymethyl methacrylate particles from the viewpoint of minimizing damage to the resin surface by the particles. Any one of these AB agents may be used alone, or two or more may be used in combination.

[0030] When the AB agent is a silicon-containing particle, its average particle size may be the same as the average particle size of the silicon-containing particle used in the second skin layer 13, from the same viewpoint as the second skin layer 13. When the AB agent is an organic particle, its average particle size may be the same as the average particle size of the organic particle used in the second skin layer 13, from the same viewpoint as the second skin layer 13.

[0031] The content of the AB agent in the first skin layer 11 may be 1500 ppm by mass or less, or 1000 ppm by mass or less, since good gas barrier properties can be obtained. Furthermore, the content of the AB agent in the first skin layer 11 may be 100 ppm by mass or more, 200 ppm by mass or more, or 250 ppm by mass or more, from the viewpoint of preventing blocking during deposition layer formation. That is, the content of the AB agent in the first skin layer 11 may be 100 to 1500 ppm by mass, 200 to 1500 ppm by mass, or 250 to 1000 ppm by mass.

[0032] In order to more fully obtain the effects of the present disclosure, the content of the antiblocking agent in the second skin layer 13 may be 1.0 times or more, or 1.2 times or more, the content of the antiblocking agent in the first skin layer 11.

[0033] First skin layer 11 may contain, for example, an antioxidant, a stabilizer, a lubricant, an antistatic agent, and the like.

[0034] The thickness of first skin layer 11 is preferably 0.1 to 2.0 μm, and more preferably 0.3 to 1.5 μm, from the viewpoint of enabling uniform film formation.

[0035] (core layer) The core layer 12 preferably contains polypropylene. From the viewpoint of enhancing the heat resistance of the base film 1, the polypropylene used for the core layer 12 may be crystalline polypropylene, or from the viewpoint of further improving the heat resistance for thermal sterilization treatment, it may be homopolypropylene, which is a homopolymer of propylene. However, as long as the effects of the present disclosure are not significantly impaired, a random copolymer of propylene and an α-olefin, or a mixture of such a copolymer with homopolypropylene, may also be used.

[0036] The polypropylene used in the core layer 12 may be a resin polymerized from fossil fuel, a recycled resin, or a resin obtained by polymerizing raw materials derived from biomass such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuel and a recycled resin or a resin obtained by polymerizing raw materials derived from biomass such as plants.

[0037] When the base film 1 includes the first skin layer 11, the core layer 12 disposed between the first skin layer 11 and the second skin layer 13 does not need to contain an AB agent.

[0038] The thickness of the core layer 12 may be 10 to 200 μm, 12 to 50 μm, or 15 to 30 μm, depending on ease of handling when made into a packaging bag.

[0039] The ratio of the thickness of first skin layer 11 to the thickness of core layer 12 (thickness of first skin layer 11 / thickness of core layer 12) may be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within the above range, the heat resistance of the entire base film 1 can be more sufficiently ensured, and the adhesion between the layers in the gas barrier film and the laminate can be further improved.

[0040] The ratio of the thickness of second skin layer 13 to the thickness of core layer 12 (thickness of second skin layer 13 / thickness of core layer 12) may be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within the above range, the heat resistance of the entire base film 1 can be more sufficiently ensured, and the adhesion between the layers in the gas barrier film and the laminate can be further improved.

[0041] (Entire base film) In the substrate film 1, the first skin layer 11 and the second skin layer 13 can be formed on the core layer 12, for example, by co-extruding the material for forming the core layer 12 with the material for forming the first skin layer 11 and the second skin layer 13. After co-extrusion, the multilayer film may be stretched by conventional means to form a uniaxially or biaxially oriented film.

[0042] In the base film 1, a first skin layer 11 is provided on one surface of the core layer 12, and a second skin layer 13 is provided on the other surface. Both surfaces of the base film 1 may be formed by the first skin layer 11 and the second skin layer 13. A layer other than the core layer 12 and the first skin layer 11 may be provided between them, or the core layer 12 and the first skin layer 11 may be in contact with each other without an intervening layer. A layer other than the core layer 12 and the second skin layer 13 may be provided between them, or the core layer 12 and the second skin layer 13 may be in contact with each other without an intervening layer.

[0043] The polypropylene content in the base film 1 may be 90% by mass or more, 95% by mass or more, or 99% by mass or more, based on the total mass of the base film. The polypropylene content may be substantially 100% by mass, based on the total mass of the base film (an embodiment in which the base film is made of polypropylene).

[0044] The thickness (total thickness) of the base film is not particularly limited, but may be, for example, 10 μm or more and 200 μm or less, 12 μm or more and 50 μm or less, or 15 μm or more and 30 μm or less.

[0045] The substrate film may have an arithmetic mean height Sa1 of 30 nm or more and 80 nm or less on the surface (first face F1) facing the first skin layer, and an arithmetic mean height Sa2 of 40 nm or more and 120 nm or less on the surface (second face F2) facing the second skin layer. While satisfying the above conditions, the first skin layer may contain a copolymer of propylene and an α-olefin. The first skin layer may be the outermost layer on one side of the substrate film, and the second skin layer may be the outermost layer on the other side of the substrate film.

[0046] Conventionally, gas barrier films are produced by forming at least a gas barrier vapor deposition layer on a base film. However, there is a problem that blocking is likely to occur when the base film with the vapor deposition layer formed thereon is wound into a roll. One method for suppressing this blocking is to use a base film having an uneven surface. However, when a gas barrier film using such a base film is subjected to a heat sterilization treatment such as retort treatment, the gas barrier properties are likely to deteriorate. Furthermore, gas barrier films are laminated with other resin films containing polypropylene, such as a sealant layer, and used as packaging materials. Therefore, gas barrier films are required to have good adhesion to other resin films, even when subjected to a heat sterilization treatment such as retort treatment after being laminated with other resin films.

[0047] In response to these problems, the above-mentioned base film, in which the first skin layer contains a copolymer of propylene and an α-olefin and satisfies the above-mentioned conditions Sa1 and Sa2, has a first skin layer as one of its outermost layers, which contains a copolymer of propylene and an α-olefin and has an arithmetic mean height Sa1 of 30 to 80 nm. When a vapor-deposited layer is formed on the first skin layer to produce a gas barrier film, even after the gas barrier film is subjected to retort treatment, the adhesion between the first skin layer and the vapor-deposited layer is good and defects such as cracks in the vapor-deposited layer can be suppressed, resulting in good gas barrier properties. Furthermore, with the above-mentioned base film, the arithmetic mean height Sa2 of the surface opposite to the first skin layer (the second skin layer side) is 40 to 120 nm, which suppresses blocking when a vapor-deposited layer is formed on the first skin layer and then wound into a roll. Furthermore, by having the arithmetic mean heights Sa1 and Sa2 of both surfaces of the base film be within the above ranges, even when a gas barrier film is produced, the gas barrier film is laminated with another resin film, and then retort treatment is performed, good adhesion to the other resin film can be obtained.

[0048] The value of Sa1 may be 30 nm or more and 80 nm or less, but may be 40 nm or more and 80 nm or less from the viewpoint that when a gas barrier film is produced, the gas barrier properties and adhesion to other resin films after retort treatment are further improved, and blocking resistance is further improved.

[0049] The value of Sa2 may be 40 nm or more and 120 nm or less, but may be 45 nm or more and 110 nm or less from the viewpoint that when a gas barrier film is produced, the gas barrier properties and adhesion to other resin films after retort treatment are further improved, and blocking resistance is further improved.

[0050] The total value of Sa1 and Sa2 (Sa1+Sa2) is not particularly limited, but may be 80 nm or more and 150 nm or less, or 85 nm or more and 145 nm or less, from the viewpoint of further improving the gas barrier properties and adhesion to other resin films after retort treatment and further improving the blocking resistance when a gas barrier film is produced.

[0051] Here, the arithmetic mean height (Sa) is a parameter indicating the surface roughness of the substrate film, and means the average height of the irregularities on the surface of the substrate film. The arithmetic mean heights Sa1 and Sa2 of both surfaces of the substrate film can be measured using a three-dimensional non-contact surface shape measurement system under the condition of a measurement area of ​​210 μm square.

[0052] The arithmetic mean heights Sa1 and Sa2 of the substrate film can be adjusted by changing the type of resin used in the first skin layer 11 and the second skin layer 13, the compounding ratio and melting point of multiple resins when multiple resins are used, the addition and amount of an antiblocking agent, the roll surface condition during extrusion, and conditions such as stretching after film formation. Among the resins used, homopolymers are hard due to their high crystallinity and are less likely to block even if they have high smoothness, but tend to have poor adhesion. On the other hand, copolymers are softer resins and tend to have improved adhesion, but tend to be more likely to block even if they have low smoothness.

[0053] <Gas barrier film> The gas barrier film according to this embodiment includes the above-described base film 1 and a vapor-deposited layer containing an inorganic oxide that is disposed on the first surface F1 of the base film 1. The gas barrier film according to this embodiment may further include a gas barrier coating layer that is disposed on the surface of the vapor-deposited layer opposite to the base film 1.

[0054] Fig. 2 is a schematic cross-sectional view showing a gas barrier film according to one embodiment. As shown in Fig. 2, the gas barrier film 10 according to this embodiment comprises, in this order, a base film 1, an anchor coat layer 2, a vapor deposition layer 3, and a gas barrier coating layer 4. The anchor coat layer 2 is disposed on the surface of the base film 1 facing the first skin layer 11. The gas barrier film does not necessarily have to comprise the anchor coat layer 2.

[0055] (Anchor coat layer) The anchor coat layer 2 is a layer for further improving the adhesion between the base film 1 and the vapor-deposited layer 3, and is provided between the base film 1 and the vapor-deposited layer 3. There are no particular restrictions on the material that constitutes the anchor coat layer 2, as long as it is capable of improving the adhesion between the base film 1 and the vapor-deposited layer 3.

[0056] For example, a material containing a reaction product of a polyol compound containing a (meth)acrylic resin and an isocyanate compound can be used as the material for the anchor coat layer 2. Note that the term "(meth)acrylic resin" refers to at least one of "acrylic resin" and the corresponding "methacrylic resin."

[0057] Examples of (meth)acrylic resins include (meth)acrylic polymers obtained by polymerizing polymerizable monomers containing (meth)acrylic monomers. The (meth)acrylic polymer may be a homopolymer or a copolymer with a polymerizable monomer other than a (meth)acrylic monomer. The (meth)acrylic resin may be a resin capable of thermal crosslinking, such as urethane curing or epoxy curing. From the viewpoint of reactivity with an isocyanate compound used as a curing agent, which will be described later, the (meth)acrylic resin may be a polyol having two or more hydroxyl groups in one molecule, and in particular, a (meth)acrylic polyol.

[0058] The (meth)acrylic polyol may be a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon (meth)acrylate with a hydroxyl group-containing monomer, or a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon (meth)acrylate with a hydroxyl group-containing monomer and a monomer component other than these (other monomer components). By copolymerizing the above-mentioned monomers, a (meth)acrylic polyol containing multiple hydroxyl groups can be obtained.

[0059] The anchor coat layer 2 may contain a curing agent. The curing agent may be an isocyanate compound having two or more NCO groups in the molecule, from the viewpoint of excellent reactivity with the (meth)acrylic resin.

[0060] The isocyanate compound may be a monomeric isocyanate. Examples of the monomeric isocyanate include aromatic or araliphatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI); and aliphatic isocyanates such as hexamethylene diisocyanate (HDI), bisisocyanatemethylcyclohexane (H6XDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane diisocyanate (H12MDI).

[0061] The isocyanate compound may be a polymer or derivative of the above-mentioned monomeric isocyanate. The isocyanate compound may be, for example, a trimer nurate type, an adduct type reacted with 1,1,1-trimethylolpropane, or a biuret type reacted with biuret. The isocyanate compound may be an isocyanate having an aromatic ring, from the viewpoint of excellent reactivity with the (meth)acrylic resin.

[0062] When the (meth)acrylic resin is a (meth)acrylic polyol, the content of the isocyanate compound may be an amount such that the number of OH groups in the acrylic polyol is equal to the number of NCO groups in the isocyanate compound.

[0063] The anchor coat layer 2 may contain a silane coupling agent to further improve adhesion to the vapor deposition layer 3. Examples of silane coupling agents include epoxy-based silane coupling agents having an epoxy group such as 3-glycidoxypropyltrimethoxysilane; amino-based silane coupling agents having an amino group such as 3-aminopropyltrimethoxysilane; mercapto-based silane coupling agents having a mercapto group such as 3-mercaptopropyltrimethoxysilane; and isocyanate-based silane coupling agents having an NCO group such as 3-isocyanatepropyltriethoxysilane. These silane coupling agents can be used alone or in combination of two or more.

[0064] Alternatively, a polyurethane resin formed from an acid group-containing polyurethane and a polyamine can be used as a material for forming the anchor coat layer 2. The polyurethane resin is obtained by bonding the acid groups of the acid group-containing polyurethane with the amino groups of a polyamine used as a crosslinking agent. In other words, the polyurethane resin can be said to be a reaction product of the acid group-containing polyurethane and the polyamine, or to be formed by crosslinking the acid group-containing polyurethane with the polyamine. The bond between the acid group of the acid group-containing polyurethane and the amino group of the polyamine may be an ionic bond (e.g., an ionic bond between a carboxyl group and a tertiary amino group) or a covalent bond (e.g., an amide bond).

[0065] A silane coupling agent or a carbodiimide compound may be added to the polyurethane resin. By adding such a compound, a crosslinked structure is formed with the polyurethane resin, thereby further improving the gas barrier properties or the adhesion between the substrate film 1 and the vapor-deposited layer 3. Commonly used silane coupling agents can be used, such as compounds in which an alkoxy group and an organic reactive group are bonded to a silicon atom.

[0066] The thickness of the anchor coat layer 2 is not particularly limited as long as it is a thickness that can improve the adhesion between the base film 1 and the vapor-deposited layer 3, but is preferably 30 nm or more. In this case, compared to when the thickness of the anchor coat layer 2 is less than 30 nm, the surface smoothness of the anchor coat layer 2 can be further improved, the thickness of the vapor-deposited layer 3 can be made more uniform, and the oxygen barrier property can also be further improved. This further improves the oxygen barrier property of the gas barrier film 10. The thickness of the anchor coat layer 2 is more preferably 40 nm or more, and even more preferably 50 nm or more. By increasing the thickness of the anchor coat layer 2, it is possible to further suppress the deterioration of the gas barrier property when an external force such as stretching is applied.

[0067] The thickness of the anchor coat layer 2 is preferably 2000 nm (2 μm) or less. In this case, the flexibility of the gas barrier film 10 is further improved, and the oxygen gas barrier properties of the gas barrier film 10 after abuse can be further improved, compared to when the thickness of the anchor coat layer 2 exceeds 2000 nm. The thickness of the anchor coat layer 2 is more preferably 1500 nm (1.5 μm) or less.

[0068] The anchor coat layer 2 can be formed, for example, by applying an anchor coat solution onto the resin layer by a method such as gravure coating, roll coating, or bar coating, and then drying it.

[0069] In order to improve the adhesion between the base film 1 and the vapor-deposited layer 3, the surface of the base film 1 on which the vapor-deposited layer 3 is to be formed may be subjected to a surface treatment such as plasma treatment or corona treatment, instead of the anchor coat layer 2. Alternatively, the anchor coat layer 2 may be provided on a surface that has been surface-treated.

[0070] (deposited layer) The vapor-deposited layer 3 contains an inorganic oxide. From the viewpoint of improving the gas barrier properties against water vapor, oxygen, etc., the vapor-deposited layer 3 may be formed directly on the anchor coat layer 2. The vapor-deposited layer 3 may be transparent.

[0071] Examples of inorganic oxides that can be used include aluminum oxide, silicon oxide, tin oxide, magnesium oxide, and mixtures thereof. From the viewpoint of excellent sterilization resistance, the inorganic oxide may be at least one selected from aluminum oxide and silicon oxide.

[0072] The thickness of the vapor-deposited layer 3 may be 5 nm or more, 10 nm or more, or 15 nm or more from the viewpoints of achieving a uniform film thickness and excellent gas barrier properties, and may be 300 nm or less, 150 nm or less, or 100 nm or less from the viewpoint of making it difficult for cracks to occur in the vapor-deposited layer 3 even when an external force is applied after film formation. From these viewpoints, the thickness of the vapor-deposited layer 3 may be 5 to 300 nm, 10 to 150 nm, or 15 to 100 nm.

[0073] The vapor-deposited layer 3 can be formed by, for example, a vacuum vapor deposition method, a plasma-assisted method, an ion-beam-assisted method, a sputtering method, a reactive vapor deposition method, etc. The vapor-deposited layer 3 may be formed by a vacuum vapor deposition method from the viewpoint of excellent productivity, or by a plasma-assisted method or an ion-beam-assisted method from the viewpoints of excellent adhesion between the vapor-deposited layer 3 and the base film 1 and improving the density of the vapor-deposited layer 3, or by a reactive vapor deposition method in which various gases such as oxygen are blown in from the viewpoint of excellent transparency of the vapor-deposited film.

[0074] Examples of the heating means for the vacuum deposition method include an electron beam heating method, a resistance heating method, an induction heating method, etc. The heating means for the vacuum deposition method may be an electron beam heating method, from the viewpoint of an excellent range of selectivity for evaporation materials.

[0075] (Gas barrier coating layer) The gas barrier film 10 may further include a gas barrier coating layer 4 on the side of the vapor deposition layer 3 opposite to the anchor coat layer 2. By including the gas barrier coating layer 4 in the gas barrier film 10, the vapor deposition layer 3 can be protected, and the gas barrier properties can be further improved.

[0076] The gas barrier coating layer 4 may contain a silicon compound or a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group. Alternatively, the gas barrier coating layer 4 may contain a water-soluble polymer having a hydroxyl group and at least one selected from the group consisting of a metal alkoxide, a silane coupling agent, and hydrolyzates thereof.

[0077] Examples of silicon compounds include Si(OR 1 )4 and R 2 Si(OR 3 ) 3. OR 1 and OR 3 are each independently a hydrolyzable group, and R 2 is an organic functional group. 2 Examples of the alkyl group include vinyl, epoxy, methacryloxy, ureido, and isocyanate groups. 1 )4 may be tetraethoxysilane (Si(OC2H5)4) from the viewpoint that it is relatively stable in an aqueous solvent after hydrolysis.

[0078] Examples of water-soluble polymers having hydroxyl groups include polyvinyl alcohol, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. The water-soluble polymer having hydroxyl groups may be polyvinyl alcohol from the viewpoint of excellent gas barrier properties.

[0079] Examples of metal alkoxides include compounds represented by the following general formula (1). M(OR 11 ) m (R 12 ) n-m …(1) In the above formula, R 11 and R 12 are each independently a monovalent organic group having 1 to 8 carbon atoms, and are preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer from 1 to n. 11 and R 12 If there are multiple 11 Comrades or R 12 They may be the same or different.

[0080] Specific examples of metal alkoxides include tetraethoxysilane [Si(OC2H5)4], triisopropoxyaluminum [Al(O-2'-C3H7)3], etc. Tetraethoxysilane and triisopropoxyaluminum are preferred because they are relatively stable in aqueous solvents after hydrolysis.

[0081] Examples of the silane coupling agent include compounds represented by the following general formula (2). Si(OR 21 ) p (R 22 ) 3-p R 23 …(2) In the above formula, R 21 represents an alkyl group such as a methyl group or an ethyl group, and R 22 represents a monovalent organic group such as an alkyl group, an aralkyl group, an aryl group, an alkenyl group, an alkyl group substituted with an acryloxy group, or an alkyl group substituted with a methacryloxy group, and R 23 represents a monovalent organic functional group, and p represents an integer of 1 to 3. 21 or R 22 If there are multiple 21 Comrades or R 22 R may be the same or different.23 Examples of the monovalent organic functional group represented by the formula (I) include a monovalent organic functional group containing a glycidyloxy group, an epoxy group, a mercapto group, a hydroxyl group, an amino group, an alkyl group substituted with a halogen atom, or an isocyanate group. Compounds in which these silane coupling agents are in the form of a polymer such as a dimer or trimer may also be used.

[0082] Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane.

[0083] The gas barrier coating layer 4 may further contain additives such as an isocyanate compound, a silane coupling agent, a dispersant, a stabilizer, a viscosity adjuster, and a colorant.

[0084] The thickness of the gas barrier coating layer 4 may be 0.1 μm or more, or 0.3 μm or more, or 5 μm or less, or 1 μm or less. The thickness of the gas barrier coating layer 4 may be 0.1 to 5 μm, or 0.3 to 1 μm.

[0085] The gas barrier coating layer 4 can be formed, for example, by dissolving a water-soluble polymer in water or a water / alcohol mixed solvent, mixing with a silicon compound or its hydrolyzate, a metal alkoxide, a silane coupling agent, etc., and applying this mixed solution onto the vapor deposition layer by a method such as gravure coating, roll coating, or bar coating, and drying it.

[0086] When the water-soluble polymer is polyvinyl alcohol, the content of polyvinyl alcohol in the mixed solution may be 20% by mass or more or 25% by mass or more based on the total solid content of the mixed solution from the viewpoint of facilitating the formation of a gas barrier coating layer, or 50% by mass or less or 40% by mass or less from the viewpoint of excellent gas barrier properties. The content of polyvinyl alcohol in the mixed solution may be 20 to 50% by mass or 25 to 40% by mass based on the total solid content of the mixed solution.

[0087] <Laminate> The laminate according to this embodiment includes the gas barrier film 10 described above and a sealant layer disposed on the surface of the gas barrier film 10 facing the second skin layer 13. The laminate according to this embodiment may further include a second base film containing polypropylene disposed on the surface of the gas barrier film 10 opposite the sealant layer.

[0088] Fig. 3 is a schematic cross-sectional view showing a laminate according to one embodiment. The laminate 20 shown in Fig. 3 has a structure in which a sealant layer 23 is laminated on the second skin layer 13 of a gas barrier film 10 via an adhesive layer 24.

[0089] Fig. 4 is a schematic cross-sectional view showing a laminate according to another embodiment. The laminate 30 shown in Fig. 4 has a structure in which a sealant layer 23 is laminated on the second skin layer 13 of the gas barrier film 10 via an adhesive layer 24, and a polypropylene-containing resin film 22 as a second base film is laminated on the gas barrier coating layer 4 of the gas barrier film 10 via the adhesive layer 24.

[0090] For example, a stretched or unstretched polypropylene film, or an unstretched polypropylene film, may be used as the sealant layer 23. By using polypropylene as the material for the sealant layer 23, the laminate 20 can be a mono-material packaging material.

[0091] The thickness of the sealant layer 23 is not particularly limited, but may be, for example, 10 μm or more or 20 μm or more, and 200 μm or less or 100 μm or less. The thickness of the sealant layer 23 may be 10 to 200 μm or 20 to 100 μm.

[0092] The adhesive layer 24 bonds the films together. Examples of adhesives that form the adhesive layer include polyurethane resins in which a bifunctional or higher isocyanate compound is reacted with a base material such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. The various polyols may be used alone or in combination of two or more.

[0093] In order to improve adhesiveness, the adhesive layer 24 may contain a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent, or the like in addition to the polyurethane resin.

[0094] The amount of the adhesive layer to be applied is, for example, 0.5 to 10 g / m from the viewpoint of obtaining the desired adhesive strength, conformability, processability, etc. 2 From the viewpoint of environmental consideration, the adhesive layer may be made of a polymer component derived from biomass or biodegradable. Also, an adhesive having barrier properties may be used for the adhesive layer.

[0095] When the laminate further comprises a resin film 22 as a second base film, the resin film 22 may be laminated on the gas barrier coating layer 4 of the gas barrier film 10 via the adhesive layer 24. As the resin film 22, for example, a film obtained by stretching homopolypropylene to impart heat resistance may be used.

[0096] The thickness of the resin film 22 is not particularly limited, but may be, for example, 3 μm or more and 200 μm or less, or 6 μm or more and 50 μm or less.

[0097] <Packaging material> Packaging materials can be produced using the above-described laminate. A laminate using the above-described gas barrier film can produce a packaging material that has sufficiently low oxygen permeability and excellent laminate strength even after heat sterilization such as retort processing. Furthermore, a laminate using the above-described gas barrier film can produce a packaging material that can suppress flavor deterioration of the contents even after heat sterilization such as retort processing. Therefore, packaging materials produced from such laminates can contain foods, beverages, pharmaceuticals, etc., and are particularly suitable for containing foods and beverages. The laminate may be made into a bag-shaped packaging material (packaging bag) by folding one laminate in half so that the sealant layers face each other, and then heat-sealing the three sides other than the folded part. Alternatively, two laminates may be stacked together so that the sealant layers face each other, and then heat-sealing the four sides to produce a bag-shaped packaging material (packaging bag).

[0098] The packaging material may be equipped with a stopper. In packaging materials equipped with a stopper, the stopper may be sandwiched and fixed between two laminated sheets forming the packaging material, or a hole may be drilled on one side of the packaging material and the spout may be glued and fixed. The spout may be provided on the top surface of the packaging material, or on the side, bottom, or diagonally upward of the packaging material. When the contents are liquid or gel-like, a straw that reaches the bottom of the packaging material may be provided in addition to the spout stopper (so-called spout) so that the contents can be directly poured into the mouth and sucked out.

[0099] Another form of packaging material with a spout is a bag-in-box in which a bag (inner bag) containing a liquid such as a soft drink or alcoholic drink is placed in a carton (outer box). That is, the laminate according to this embodiment can be used for a bag-in-box bag, particularly a bag equipped with a spout (tube) for pouring.

[0100] When the laminate is used as a packaging material with a spout, the spout portion and the entire spout of the cap may be formed from the same resin as the base film of the gas barrier film, from the viewpoint of improving recyclability. [Example]

[0101] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0102] <Preparation of anchor coat layer forming composition> The anchor coat layer-forming composition was prepared as follows. γ-Isocyanatepropyltrimethoxysilane and acrylic polyol were added to ethyl acetate as a dilution solvent, mixed, and stirred. The acrylic polyol was added in a ratio of 5 parts by mass per 1 part by mass of γ-isocyanatepropyltrimethoxysilane. GS-5756 (trade name) manufactured by Mitsubishi Rayon Co., Ltd. was used as the acrylic polyol. Next, tolylene diisocyanate (TDI) was added as an isocyanate compound so that the number of NCO groups was equal to the number of OH groups in the acrylic polyol. The resulting mixed solution was diluted with the dilution solvent to obtain an anchor coat layer-forming composition with a solids concentration of 2% by mass.

[0103] <Preparation of Composition for Forming Gas Barrier Coating Layer> A composition for forming a gas barrier coating layer was prepared by mixing the following raw material solutions A, B, and C in a mass ratio of 0.5:0.4:0.1. (Raw material liquid A) Polyvinyl alcohol (trade name "Kuraray Poval 60-98", manufactured by Kuraray Co., Ltd.) was dissolved in water to a solid content of 5% by mass. (Raw material liquid B) Tetraethoxysilane (trade name "KBE04", solid content: 100% by mass, manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter also referred to as "TEOS") as a metal alkoxide, methanol (manufactured by Kanto Chemical Co., Ltd.), and 0.1N hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) were mixed in a mass ratio of 17 / 10 / 73 and dissolved to a solid content of 5% by mass. (Raw material liquid C) 1,3,5-tris(3-methoxysilylpropyl)isocyanurate as a silane coupling agent was added to a mixed solvent of water / isopropyl alcohol=1 / 1 (mass ratio) and dissolved so that the solid content became 5 mass %.

[0104] Example 1 (Preparation of base film) First, a 1000 μm-thick laminated film with a three-layer structure (first skin layer / core layer / second skin layer) was produced by melt-extruding the materials for each layer using a screw extruder. Homopolypropylene was used as the core layer material, and an ethylene-propylene random copolymer (hereinafter referred to as "copolymer PP (1)") with a melting point of 132°C was used as the first and second skin layers. Synthetic silica particles (average particle size 5 μm) were added to the second skin layer as an antiblocking agent (AB agent) at the content shown in Table 1.

[0105] Next, the laminated film was stretched 5 times in the machine direction (MD) and 10 times in the transverse direction (TD) using a tenter, and the surface on the first skin layer side was subjected to a corona treatment to obtain a simultaneously biaxially stretched polypropylene (PP) film with a thickness of 20 μm as a substrate film. The machine direction is the direction of melt extrusion, and the transverse direction is the direction perpendicular to the melt extrusion direction. In the substrate film, the first skin layer was 1 μm thick, the core layer was 18 μm thick, and the second skin layer was 1 μm thick. The surface on the first skin layer side of the substrate film is the first side on which a vapor deposition layer will be formed, and the surface on the second skin layer side is the second side.

[0106] (Preparation of gas barrier film) The anchor coat layer-forming composition prepared as described above was applied to the first surface of the substrate film using a bar coater to a dry thickness of 0.2 μm, and then dried at 60°C for 1 minute to form an anchor coat layer. Next, a 20 nm thick alumina vapor deposition layer was formed on the anchor coat layer using a vacuum deposition device. Subsequently, the gas barrier coating layer-forming composition prepared as described above was applied to the surface of the vapor deposition layer using a bar coater to a dry thickness of 0.3 μm, and then dried in an oven at 50°C for 1 minute to form a gas barrier coating layer. This resulted in a gas barrier film.

[0107] <Example 2> A gas barrier film was produced in the same manner as in Example 1, except that the average particle size of the synthetic silica particles added to the second skin layer was changed as shown in Table 1, and polymethyl methacrylate (PMMA) particles (average particle size 2 μm) were further added to the second skin layer as an AB agent to the content shown in Table 1.

[0108] Example 3 A gas barrier film was produced in the same manner as in Example 1, except that the content of synthetic silica particles in the second skin layer was changed as shown in Table 1 and PMMA particles (average particle diameter 4 μm) as an AB agent were further added to the second skin layer to the content shown in Table 1.

[0109] Example 4 A gas barrier film was produced in the same manner as in Example 1, except that an ethylene-1-butene-1-propylene random copolymer (hereinafter referred to as "copolymer PP (2)") with a melting point of 148°C was used as the material for the first skin layer and the second skin layer.

[0110] <Example 5> A gas barrier film was produced in the same manner as in Example 1, except that the average particle size and content of the synthetic silica particles in the second skin layer were changed as shown in Table 1.

[0111] <Comparative Example 1> Gas barrier films were produced in the same manner as in Example 1, except that the content of the synthetic silica particles in the second skin layer was changed as shown in Table 1.

[0112] <Comparative Example 2> A gas barrier film was produced in the same manner as in Example 1, except that copolymer PP (2) was used as the material for the first skin layer and the second skin layer, the average particle size and content of the synthetic silica particles in the second skin layer were changed as shown in Table 1, and PMMA particles (average particle size 4 μm) were further added to the second skin layer as an AB agent to achieve the content shown in Table 1.

[0113] <Comparative Examples 3 and 4> A gas barrier film was produced in the same manner as in Example 1, except that synthetic silica particles were not added to the second skin layer, and instead PMMA particles (average particle diameter 4 μm) were added to the content shown in Table 1.

[0114] <Examples 6 to 10 and Comparative Examples 5 to 8> The gas barrier films of Examples 6 to 10 and Comparative Examples 5 to 8 were produced in the same manner as Examples 1 to 5 and Comparative Examples 1 to 4, except that synthetic silica particles (average particle diameter 2 μm) were added as an AB agent to the first skin layer in the amounts shown in Table 2.

[0115] <Examples 11 to 15 and Comparative Examples 9 to 12> The gas barrier films of Examples 11 to 15 and Comparative Examples 9 to 12 were produced in the same manner as Examples 1 to 5 and Comparative Examples 1 to 4, except that acrylic resin particles (average particle diameter 2 μm) were added as an AB agent to the first skin layer in the amounts shown in Table 3.

[0116] <Measurement of arithmetic mean height Sa> The arithmetic mean height Sa1 of the surface on the first skin layer side and the arithmetic mean height Sa2 of the surface on the second skin layer side of the substrate films produced in the Examples and Comparative Examples were measured using a three-dimensional non-contact surface profile measurement system (VertScan R3300h Lite, manufactured by Ryoka Systems Co., Ltd.) over a measurement area of ​​210 μm square. The results are shown in Tables 1 to 3.

[0117] [Preparation of laminate A] A 60 μm-thick unstretched polypropylene film serving as a sealant layer was bonded to the side (second side) opposite the gas barrier coating layer (second skin layer side) of each of the gas barrier films produced in the Examples and Comparative Examples by dry lamination using a two-component curing urethane adhesive, to produce a laminate A consisting of gas barrier coating layer / vapor deposition layer / anchor coat layer / first skin layer / core layer / second skin layer / adhesive layer / sealant layer.

[0118] [Preparation of laminate B] The gas barrier coating layer side (first side) of the gas barrier film produced in the Examples and Comparative Examples was bonded to a 20 μm-thick biaxially oriented polypropylene film (OPP) as a resin film using a two-component curing urethane adhesive by dry lamination. Then, the second skin layer side (second side) of the gas barrier film was bonded to a 60 μm-thick unstretched polypropylene film (CPP) as a sealant layer using a two-component curing urethane adhesive by dry lamination to produce a laminate B consisting of resin film (OPP) / gas barrier coating layer / vapor deposition layer / anchor coat layer / first skin layer / core layer / second skin layer / adhesive layer / sealant layer (CPP).

[0119] [evaluation] <Blocking resistance> In the preparation of the gas barrier film described above, an anchor coat layer and a vapor-deposited layer were formed on the first skin layer of the substrate film to form a test specimen for evaluating blocking resistance. Two such test specimens were prepared and stacked so that the surface of the vapor-deposited layer of one test specimen faced the surface of the other test specimen opposite the vapor-deposited layer (the second skin layer side). A pressure of 1 MPa was applied, and the test specimens were left for 24 hours at 25°C and 65% RH. After this time, the stacked test specimens were cut into pieces measuring 150 mm wide and 500 mm long, and the peel strength between the two test specimens was measured. The peel strength was measured using a Tensilon universal material testing machine (RTC-1250, manufactured by A&D Co., Ltd.). This peel strength was used as an index of the blocking resistance of the substrate film and was evaluated according to the following criteria. The results are shown in Tables 1 to 3. A grade of "A" indicates that the substrate film has excellent blocking resistance. A: Peel strength is less than 0.5N / 150mm. B: Peel strength is 0.5N / 150mm or more.

[0120] <Making packaging bags> An A4-sized sheet (297 mm long x 210 mm short) was cut out from the laminate A prepared above. This sheet was folded in half so that the short edges overlapped, and the overlapping long edges were heat-sealed to prepare a packaging bag (pouch) with an opening. Next, 150 g of boiled ground chicken (containing 700 mg of amino acids per 100 g) was filled into the packaging bag as the contents, and the opening was then heat-sealed to seal. The sealed packaging bag was subjected to a retort treatment, and a retort-treated packaging bag was obtained. The retort treatment (retort sterilization) was carried out by holding the contents at 120°C for 30 minutes using a hot water storage retort oven.

[0121] <Oxygen permeability measurement> After retort sterilization, the packaging bag was opened, and a portion (100 mm x 100 mm) of Laminate A was cut out as an evaluation sample. The oxygen transmission rate (OTR) of the cut-out sample was measured at 30°C and 70% RH using an oxygen transmission rate measuring device (product name "OX-TRAN2 / 20", manufactured by Modern Control). This measured value was used as an index of the oxygen barrier property of Laminate A. The OTR measurement was performed in accordance with JIS K7126-2. The OTR results are shown in Tables 1 to 3.

[0122] <Evaluation of flavor deterioration> The packaging bag after retort processing was opened, and the odor inside the packaging bag with the contents inside (presence or absence of an unpleasant odor such as a retort odor other than the original odor of the contents) and the taste of the removed contents (presence or absence of deterioration from the original taste of the contents) were evaluated by four panelists using the following criteria, and an average score was calculated. If the average score was 3.5 or higher, it was determined that flavor deterioration had been suppressed. The results are shown in Tables 1 to 3. (Odor) 5: Almost no unpleasant odor 4: There is a slight strange smell, but it is not a problem 3: The odor is a little strong and problematic 2: There is a strong odor and it is problematic 1: The odor is very strong and problematic (taste) 5: Feel the umami 4: The flavor is slightly reduced, but there is no problem 3: There is no umami and the taste has deteriorated, which is problematic 2: The taste has deteriorated and there are problems. 1: The taste has deteriorated significantly and there is a problem.

[0123] <Adhesion strength after retort treatment> Using the laminate B, a packaging bag with four sealed sides was prepared and filled with water. This was then subjected to a retort sterilization treatment at 130°C for 30 minutes. The retort sterilized laminate B was cut into a size of 150 mm wide x 500 mm long, and the adhesion strength was measured. The adhesion strength was measured between the biaxially oriented polypropylene film (OPP) and the first skin layer, and between the second skin layer and the unoriented polypropylene film (CPP). The results are shown in Tables 1 to 3.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3] [Explanation of symbols]

[0127] 1...base film, 2...anchor coat layer, 3...vapor deposition layer, 4...gas barrier coating layer, 10...gas barrier film, 11...first skin layer, 12...core layer, 13...second skin layer, 20, 30...laminate, 22...resin film, 23...sealant layer, 24...adhesive layer

Claims

1. A substrate film and a vapor deposition layer containing an inorganic oxide disposed on a first surface, which is one surface of the substrate film; the base film comprises a first skin layer having the first surface, a second skin layer having a second surface that is the surface of the base film opposite to the first surface, and a core layer; the first skin layer comprises a copolymer of propylene and an α-olefin; The second skin layer contains silicon-containing particles in a ratio of 1500 ppm by mass to 4000 ppm by mass, the second skin layer and the core layer both comprise polypropylene; the vapor-deposited layer comprises aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof; A gas barrier film, wherein the first surface of the base film has an arithmetic mean height Sa1 of 30 nm or more and 80 nm or less, and the second surface has an arithmetic mean height Sa2 of 40 nm or more and 120 nm or less.

2. The gas barrier film according to claim 1 , wherein the second skin layer further comprises an antiblocking agent other than the silicon-containing particles.

3. 2. The gas barrier film according to claim 1, wherein the silicon-containing particles have an average particle size of 1 μm or more and 6 μm or less.

4. 2. The gas barrier film according to claim 1, wherein the value of Sa1+Sa2 is 80 nm or more and 150 nm or less.

5. The gas barrier film of claim 1 , wherein the first skin layer comprises an antiblocking agent.

6. The gas barrier film according to claim 1 , wherein the vapor-deposited layer comprises aluminum oxide or silicon oxide.

7. The gas barrier film according to claim 1 , further comprising a gas barrier coating layer disposed on the surface of the vapor deposition layer opposite to the substrate film.

8. The gas barrier film according to claim 1 , further comprising an anchor coat layer disposed between the substrate film and the vapor deposition layer.

9. A laminate comprising the gas barrier film according to any one of claims 1 to 8 and a sealant layer disposed on the second skin layer side of the gas barrier film.

10. The laminate according to claim 9 , further comprising a resin film containing polypropylene arranged on the opposite side of the gas barrier film from the sealant layer.

11. A packaging bag produced by producing the laminate according to claim 9.

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