Gas barrier film, laminate, and packaging bag

Abstract

A gas barrier film according to one aspect of the present disclosure is provided with: a base film comprising polypropylene; and a vapor-deposited layer containing an inorganic oxide, the vapor-deposited layer being disposed on a first surface, which is one surface of the base film, the base film being provided with a second skin layer having a second surface, which is the surface of the base film on the opposite side from the first surface, and a core layer, the second skin layer having a second surface, which is the surface of the base film on the opposite side from the first surface. The second skin layer contains silicon-containing particles at a ratio of 1500 ppm by mass or more and 4000 ppm by mass or less.

Description

Technical Field

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

[0002] Packaging materials such as packaging bags used for food, beverages, and pharmaceuticals require gas barrier properties to prevent the ingress of gases such as oxygen, which can cause deterioration, in order to prevent the contents from spoiling and becoming corrupted, thereby maintaining their functionality and quality. Therefore, these packaging materials have traditionally used films with gas barrier properties (gas barrier films).

[0003] As such a gas barrier film, for example, the following is known: a gas barrier film comprising a substrate containing a thermoplastic resin, a metal oxide layer, and a gas barrier coating layer in this order, wherein on the surface of the gas barrier coating layer, the ratio of silicon atoms to carbon atoms (Si / C) measured by X-ray photoelectron spectroscopy is greater than 0 and less than 0.50 (see Patent Document 1 below).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-50299 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, in the gas barrier film described in Patent Document 1, when the contents are placed in a packaging bag and retorted, the flavor of the contents may deteriorate, and this point leaves room for improvement.

[0009] The present disclosure has been made in view of the above-mentioned problems, and an object thereof is to provide a gas barrier film that can suppress flavor deterioration of contents after retorting and has good oxygen barrier properties even after retorting, and a laminate and packaging bag using the gas barrier film.

[0010] Solutions for solving problems

[0011] In order to solve the above-mentioned problems, the present disclosure provides the following gas barrier films, laminates, and packaging bags.

[0012] [1] A gas barrier film comprising: a base film comprising polypropylene; and a vapor-deposited layer comprising an inorganic oxide, the vapor-deposited layer being arranged on a first surface which is one surface of the base film, the base film comprising a second skin layer and a core layer, the second skin layer having a second surface which is a surface of the base film opposite to the first surface, the second skin layer containing silicon-containing particles at a ratio of not less than 1500 ppm by mass and not more than 4000 ppm by mass.

[0013] [2] The gas barrier film according to [1] above, wherein the second skin layer further contains an anti-blocking agent other than the silicon-containing particles.

[0014] [3] The gas barrier film according to [1] or [2] above, wherein the average particle size of the silicon-containing particles is 1 μm or more and 6 μm or less.

[0015] [4] The gas barrier film according to any one of [1] to [3] above, wherein the base film includes a first skin layer, and the first skin layer has the first surface.

[0016] [5] The gas barrier film according to [4] above, wherein the first skin layer comprises a copolymer of propylene and α-olefin, the arithmetic mean height Sa1 of the first surface of the substrate film is greater than or equal to 30 nm and less than or equal to 80 nm, and the arithmetic mean height Sa2 of the second surface is greater than or equal to 40 nm and less than or equal to 120 nm.

[0017] [6] The gas barrier film according to [5] above, wherein the value of Sa1+Sa2 is 80 nm or more and 150 nm or less.

[0018] [7] The gas barrier film according to [5] or [6] above, wherein the first skin layer contains an anti-blocking agent.

[0019] [8] The gas barrier film according to any one of [1] to [7] above, wherein the vapor-deposited layer comprises aluminum oxide or silicon oxide.

[0020] [9] The gas barrier film according to any one of [1] to [8], further comprising a gas barrier coating layer, wherein the gas barrier coating layer is arranged on the surface of the deposited layer opposite to the base film.

[0021]

[10] The gas barrier film according to any one of [1] to [9], further comprising an anchor coating layer, wherein the anchor coating layer is arranged between the base film and the vapor-deposited layer.

[0022]

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

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

[0023]

[12] The laminate according to

[11] , further comprising a resin film made of polypropylene, wherein the resin film is arranged on the side of the gas barrier film opposite to the sealant layer.

[0024]

[13] A packaging bag, which is formed by molding the laminate described in

[11] or

[12] .

[0025] Effects of the Invention

[0026] According to the present disclosure, a gas barrier film that can suppress flavor deterioration of contents after retorting and has good oxygen barrier properties even after retorting, and a laminate and packaging bag using the gas barrier film can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic cross-sectional view showing a base film according to one embodiment of the present disclosure.

[0028] Figure 2 This is a schematic cross-sectional view showing a gas barrier film according to one embodiment of the present disclosure.

[0029] Figure 3 This is a schematic cross-sectional view showing a laminated body according to one embodiment of the present disclosure.

[0030] Figure 4 This is a schematic cross-sectional view showing a laminated body according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings as appropriate. However, the present disclosure is not limited to the following embodiments.

[0032] <Base film>

[0033] The substrate film is a film (base film) that serves as a support for the gas barrier film and comprises polypropylene. The substrate film has a vapor-deposited layer comprising an inorganic oxide formed on a first surface, which is one surface thereof. The substrate film comprises a second skin layer and a core layer, wherein the second skin layer has a second surface that is a surface opposite to the first surface, and the second skin layer contains silicon-containing particles at a ratio of 1500 mass ppm to 4000 mass ppm. The substrate film may further comprise a first skin layer, wherein the first skin layer has the first surface.

[0034] The gas barrier film having a deposited layer formed on the first surface of the substrate film includes a second skin layer satisfying the above conditions, thereby suppressing flavor degradation of the contents after retorting and maintaining good oxygen barrier properties even after retorting.

[0035] Figure 1 This is a schematic cross-sectional view showing a base film according to one embodiment. Figure 1The illustrated substrate film has a three-layer structure consisting of a first skin layer 11, a core layer 12, and a second skin layer 13. The first skin layer 11 has a first surface F1, and the second skin layer 13 has a second surface F2. It should be noted that the substrate film may also have a two-layer structure consisting of the second skin layer 13 and the core layer 12, or a multilayer structure consisting of four or more layers including layers other than the first skin layer 11, the core layer 12, and the second skin layer 13.

[0036] (Second epidermis)

[0037] The second epidermal layer 13 contains silicon-containing particles. Examples of silicon-containing particles include silicon dioxide particles and silicate particles. Examples of silicate particles include aluminum silicate and calcium silicate. It should be noted that the silicon-containing particles can be an anti-blocking agent. Furthermore, the shape of the silicon-containing particles is not particularly limited, but from the perspective of less likely damaging the first epidermal layer 11 in contact when curled, they are preferably spherical or substantially spherical. One type of silicon-containing particle may be used alone, or two or more types may be used in combination.

[0038] The second skin layer 13 preferably contains polypropylene. The second skin layer 13 may contain homopolypropylene or a copolymer of propylene and other monomers.

[0039] Other monomers used in the copolymer include, for example, α-olefins such as ethylene, 1-butene, and 1-hexene. The second skin layer 13 may comprise a copolymer of propylene and an α-olefin. The copolymer may be a random copolymer. Furthermore, the melting point of the resin used in the second skin layer 13 may be 130 to 150°C.

[0040] 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, based on the total amount of monomer units, and may be 99.7 mol% or less, 99.5 mol% or less, 99 mol% or less, or 98 mol% or less.

[0041] The polypropylene used in the second skin layer 13 may be a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants.

[0042] 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, a good anti-blocking effect and a good odor adsorption effect can be obtained by the silicon-containing particles. Thus, even when the contents are placed in a packaging bag and retorted, deterioration of the flavor of the contents can be suppressed. On the other hand, when the content of silicon-containing particles in the second skin layer 13 is 4000 ppm by mass or less, the silicon-containing particles can be suppressed from falling off or from causing scratches when the gas barrier film is produced. This can suppress deterioration in the oxygen barrier properties of the gas barrier film, and the gas barrier film can have good oxygen barrier properties even after retorting. To more fully achieve the above-mentioned effects, the content of silicon-containing particles in the second skin layer 13 is preferably 1500 to 3500 ppm by mass, and more preferably 2000 to 3500 ppm by mass.

[0043] The average particle size of the silicon-containing particles is preferably 1 to 6 μm. In this specification, the average particle size is the weight average diameter measured by the coal tar method. When the average particle size of the silicon-containing particles is 1 μm or more, a good anti-adhesion effect and a good odor adsorption effect can be obtained by the silicon-containing particles. As a result, even when the contents are placed in a packaging bag and subjected to a retort treatment, the deterioration of the flavor of the contents can be suppressed. On the other hand, by having an average particle size of the silicon-containing particles of 6 μm or less, when making a gas barrier film, it is possible to suppress the silicon-containing particles from falling off or the formation of scratches due to the silicon-containing particles. As a result, the deterioration of the oxygen barrier properties of the gas barrier film can be suppressed, and the gas barrier film can have good oxygen barrier properties even after the retort treatment. From the viewpoint of more fully obtaining the above-mentioned effects, the average particle size of the silicon-containing particles is more preferably 2 to 5 μm.

[0044] The second epidermal layer 13 may also contain other anti-blocking agents (hereinafter also referred to as "AB agents") in addition to the silicon-containing particles. 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 them, acrylic resin particles or polymethyl methacrylate particles are preferably used from the viewpoint of minimizing damage to the resin surface caused by the particles. Any of these AB agents may be used alone, or two or more may be used in combination.

[0045] 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 greater, 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 suppress the organic particles from falling off or causing scratches due to the organic particles when producing the gas barrier film. This can suppress the deterioration of the oxygen barrier properties of the gas barrier film, and the gas barrier film can have good oxygen barrier properties even after a retort treatment. From the viewpoint of more fully achieving the above-mentioned effects, the average particle size of the organic particles is more preferably 2 to 5 μm.

[0046] When the second skin layer 13 contains another AB agent, its content is preferably such that the total content of the silicon-containing particles and the other AB agent is 2000-4500 mass ppm, 2000-4000 mass ppm, or 2500-4000 mass ppm. By keeping the content of the other AB agent within this range, the anti-blocking performance can be further improved without impairing the effects of the present disclosure.

[0047] The second skin layer 13 may contain, for example, an antioxidant, a stabilizer, a lubricant, an antistatic agent, and the like.

[0048] From the viewpoint of achieving uniform film formation, the thickness of the second skin layer 13 is preferably 0.1 to 2.0 μm, more preferably 0.3 to 1.5 μm.

[0049] (First epidermis)

[0050] The first skin layer 11 preferably contains polypropylene. The first skin layer 11 may contain homopolypropylene or a copolymer of propylene and other monomers. The polypropylene used in the second skin layer 13 can be used. The first skin layer 11 in the substrate film 1 can relax the stress applied to the deposited layer due to shrinkage of the substrate film 1 after heat sterilization, thereby suppressing damage to the deposited layer.

[0051] The first skin layer 11 may include 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 deposited layer. Examples of α-olefins include ethylene, 1-butene, and 1-hexene. Alpha-olefins 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.

[0052] The polypropylene used in the first skin layer 11 may be a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants.

[0053] The first epidermal layer 11 may or may not contain an AB agent. When an outer layer film such as the second base film described later is laminated on the side of the first epidermal layer 11 of the gas barrier film, the inclusion of an AB agent in the first epidermal layer 11 can improve the adhesion between the gas barrier film and the outer layer film. The AB agent may be silicon-containing particles or other AB agents other than silicon-containing particles. 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 them, acrylic resin particles or polymethyl methacrylate particles are preferably used from the viewpoint of less damage to the resin surface caused by the particles. Any one of these AB agents may be used alone, or two or more may be used in combination.

[0054] When the AB agent is silicon-containing particles, from the same perspective as the second skin layer 13, the average particle size thereof can be the same as the average particle size of the silicon-containing particles used in the second skin layer 13. When the AB agent is organic particles, from the same perspective as the second skin layer 13, the average particle size thereof can be the same as the average particle size of the organic particles used in the second skin layer 13.

[0055] To achieve good gas barrier properties, the content of the AB agent in the first skin layer 11 can be 1500 mass ppm or less, or 1000 mass ppm or less. Furthermore, to prevent blocking during deposition, the content of the AB agent in the first skin layer 11 can be 100 mass ppm or more, 200 mass ppm or more, or even 250 mass ppm or more. Specifically, the content of the AB agent in the first skin layer 11 can be 100-1500 mass ppm, 200-1500 mass ppm, or 250-1000 mass ppm.

[0056] From the viewpoint of more fully achieving the effects of the present disclosure, the content of the anti-blocking agent in the second skin layer 13 may be 1.0 times or more, or 1.2 times or more, the content of the anti-blocking agent in the first skin layer 11 .

[0057] The first skin layer 11 may contain, for example, an antioxidant, a stabilizer, a lubricant, an antistatic agent, and the like.

[0058] From the viewpoint of achieving uniform film formation, the thickness of the first skin layer 11 is preferably 0.1 to 2.0 μm, more preferably 0.3 to 1.5 μm.

[0059] (core layer)

[0060] The core layer 12 preferably contains polypropylene. To improve the heat resistance of the base film 1, the polypropylene used in the core layer 12 may be crystalline polypropylene. To further improve heat resistance for heat sterilization, the polypropylene used in the core layer 12 may be homopolypropylene, which is a homopolymer of propylene. However, within the scope that does not significantly impair the effects of the present disclosure, random copolymers of propylene and α-olefins, or mixtures of such copolymers with homopolypropylene, may also be used.

[0061] The polypropylene used in the core layer 12 may be a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants. When using these resins, they may be used alone or in combination with a resin polymerized from fossil fuels, a recycled resin, or a resin polymerized from raw materials such as plants.

[0062] 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 may not contain the AB agent.

[0063] The thickness of the core layer 12 may be 10 to 200 μm, 12 to 50 μm, or 15 to 30 μm, in view of ease of handling when formed into a packaging bag.

[0064] The ratio of the thickness of the first skin layer 11 to the thickness of the core layer 12 (thickness of the first skin layer 11 / thickness of the core layer 12) can be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within this range, the heat resistance of the entire substrate film 1 can be more fully ensured, and the adhesion between the gas barrier film and the layers in the laminate can be further improved.

[0065] The ratio of the thickness of the second skin layer 13 to the thickness of the core layer 12 (second skin layer 13 thickness / core layer 12 thickness) can be 1 / 100 to 1 / 5, or 1 / 70 to 1 / 10. When the thickness ratio is within this range, the heat resistance of the entire substrate film 1 can be more fully ensured, and the adhesion between the gas barrier film and the layers in the laminate can be further improved.

[0066] (Base film as a whole)

[0067] In the substrate film 1, the first skin layer 11 and the second skin layer 13 can be formed on the core layer 12 by, for example, coextruding the material forming the core layer 12 with the material forming the first skin layer 11 and the second skin layer 13. After coextrusion, the multilayer film can be stretched by conventional means to produce a uniaxially or biaxially oriented film.

[0068] In the base film 1, a first skin layer 11 is provided on one surface of a core layer 12, and a second skin layer 13 is provided on the other surface. Both surfaces of the base film 1 can be formed by the first skin layer 11 and the second skin layer 13. A layer other than the first skin layer 11 may be provided between the core layer 12 and the first skin layer 11, or the core layer 12 and the first skin layer 11 may be in contact with each other without interposing another layer. A layer other than the first skin layer 13 may be provided between the core layer 12 and the second skin layer 13, or the core layer 12 and the second skin layer 13 may be in contact with each other without interposing another layer.

[0069] The polypropylene content of the substrate 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 substrate film. The polypropylene content may be substantially 100% by mass, based on the total mass of the substrate film (in the embodiment where the substrate film is formed of polypropylene).

[0070] The thickness (total thickness) of the base film is not particularly limited, but may be, for example, 10 μm to 200 μm, 12 μm to 50 μm, or 15 μm to 30 μm.

[0071] The substrate film may have an arithmetic mean height Sa1 of 30 nm to 80 nm on the surface of the first skin layer side (first surface F1), and an arithmetic mean height Sa2 of 40 nm to 120 nm on the surface of the second skin layer side (second surface F2). While satisfying these conditions, the first skin layer may comprise a copolymer of propylene and an α-olefin. The first skin layer may be one outermost layer of the substrate film, and the second skin layer may be the other outermost layer of the substrate film.

[0072] In the past, gas barrier films were manufactured by forming at least a gas barrier vapor-deposited layer on a substrate film. However, there was a problem that the substrate film with the vapor-deposited layer was easily blocked when it was wound into a roll. As a method for suppressing the occurrence of this blocking, a method of using a substrate film with uneven surfaces can be cited. However, when a gas barrier film using such a substrate film is subjected to a heat sterilization treatment such as a retort treatment, there is a problem that the gas barrier properties are easily reduced. In addition, gas barrier films are laminated with other resin films containing polypropylene, such as a sealant layer, and used as packaging materials. Therefore, for gas barrier films, it is required that: even when a heat sterilization treatment such as a retort treatment is applied after lamination with other resin films, good adhesion with other resin films can be obtained.

[0073] To address these problems with the prior art, a substrate film having a first skin layer comprising a copolymer of propylene and α-olefin and satisfying the aforementioned conditions of Sa1 and Sa2 is provided. By providing a first skin layer comprising a copolymer of propylene and α-olefin and having an arithmetic mean height Sa1 of 30 nm to 80 nm as the outermost layer, a vapor-deposited layer is formed on the first skin layer to produce a gas barrier film. Even when the gas barrier film is subjected to a retort treatment, the adhesion between the first skin layer and the vapor-deposited layer is excellent, and defects such as cracks in the vapor-deposited layer are suppressed, resulting in excellent gas barrier properties. Furthermore, with the substrate film, the arithmetic mean height Sa2 of the surface opposite to the first skin layer (the second skin layer side) is 40 nm to 120 nm, which prevents blocking when the vapor-deposited layer is wound into a roll after forming the vapor-deposited layer on the first skin layer. Furthermore, when the arithmetic mean heights Sa1 and Sa2 of both surfaces of the substrate film are within the above ranges, even when a gas barrier film is produced and laminated with another resin film and then subjected to a retort treatment, good adhesion to the other resin film can be achieved.

[0074] The Sa1 value can be greater than 30 nm and less than 80 nm, but when a gas barrier film is produced, it can also be greater than 40 nm and less than 80 nm from the viewpoint of further improving the gas barrier properties after steaming treatment and the adhesion with other resin films, and further improving the blocking resistance.

[0075] The Sa2 value can be greater than 40 nm and less than 120 nm, but in the case of producing a gas barrier film, it can also be greater than 45 nm and less than 110 nm from the viewpoint of further improving the gas barrier properties after steaming treatment and the adhesion with other resin films, and further improving the blocking resistance.

[0076] The total value of Sa1 and Sa2 (Sa1+Sa2) is not particularly limited, but in the case of producing a gas barrier film, it can be greater than 80 nm and less than 150 nm, or greater than 85 nm and less than 145 nm, from the viewpoint of further improving the gas barrier properties and the adhesion with other resin films after the steaming treatment, and further improving the blocking resistance.

[0077] Here, the arithmetic mean height (Sa) is a parameter indicating the surface roughness of a substrate film and refers to the average height of the concavities and convexities on the substrate film surface. The arithmetic mean heights Sa1 and Sa2 of the two surfaces of the substrate film can be measured using a three-dimensional non-contact surface profilometer using a measurement area of ​​210 μm square.

[0078] The arithmetic mean heights Sa1 and Sa2 of the substrate film can be adjusted by changing the type of resin used in the first epidermal layer 11 and the second epidermal layer 13, the difference in their mixing ratio and melting point when using multiple resins, the addition of an anti-blocking agent and its mixing amount, the roller surface state during extrusion, the stretching after film formation, etc. As the resin used, homopolymers are hard due to their high crystallinity and are not easy to adhere even if they have high smoothness, but there is a trend that adhesion decreases. On the other hand, copolymers are easy to improve adhesion due to their soft resins, but there is a trend that they are easy to adhere even if they have low smoothness.

[0079] Gas barrier film

[0080] The gas barrier film of this embodiment includes: the aforementioned base film 1; and a vapor-deposited layer comprising an inorganic oxide, the vapor-deposited layer being disposed on the first surface F1 of the base film 1. Furthermore, the gas barrier film of this embodiment may further include a gas barrier coating layer disposed on the surface of the vapor-deposited layer opposite to the base film 1.

[0081] Figure 2 : is a schematic cross-sectional view showing a gas barrier film according to one embodiment. Figure 2 As shown, the gas barrier film 10 of this embodiment includes, in this order, a base film 1, an anchor coat layer 2, a vapor-deposited layer 3, and a gas barrier coating layer 4. The anchor coat layer 2 is disposed on the surface of the base film 1 on the first skin layer 11 side. It should be noted that the gas barrier film does not necessarily need to include the anchor coat layer 2.

[0082] (Anchor Coating)

[0083] The anchor coating 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. The material constituting the anchor coating layer 2 is not particularly limited as long as it can improve the adhesion between the base film 1 and the vapor-deposited layer 3.

[0084] As the material of the anchor coating layer 2, for example, a material comprising a reaction product of a polyol compound and an isocyanate compound can be used, wherein the polyol compound comprises a (meth)acrylic resin. It should be noted that "(meth)acrylic resin" refers to at least one of "acrylic resin" and its corresponding "methacrylic resin."

[0085] Examples of the (meth)acrylic resin include (meth)acrylic polymers obtained by polymerizing polymerizable monomers including (meth)acrylic monomers. The (meth)acrylic polymer may be a homopolymer or a copolymer with a polymerizable monomer other than the (meth)acrylic monomer. The (meth)acrylic resin may be a resin that can be thermally crosslinked by urethane curing, epoxy curing, or the like. From the perspective 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 may be a (meth)acrylic polyol in particular.

[0086] The (meth)acrylic polyol may be a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon (meth)acrylate and a hydroxyl-containing monomer, or a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon (meth)acrylate, a hydroxyl-containing monomer, and other monomer components (other monomer components). By copolymerizing the above-mentioned monomers, a (meth)acrylic polyol containing multiple hydroxyl groups can be obtained.

[0087] The anchor coating layer 2 may contain a curing agent. As the curing agent, an isocyanate compound having two or more NCO groups in the molecule may be used because of its excellent reactivity with the (meth)acrylic resin.

[0088] The isocyanate compound may be a monomeric isocyanate. Examples of monomeric isocyanates include aromatic or aromatic aliphatic isocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI); and aliphatic isocyanates such as hexamethylene diisocyanate (HDI), diisocyanatomethylcyclohexane (H6XDI), isophorone diisocyanate (IPDI), and dicyclohexylmethane diisocyanate (H12MDI).

[0089] The isocyanate compound may also be a polymer or derivative of the aforementioned monomeric isocyanates. For example, the isocyanate compound may have a trimer-type urate, an adduct-type isocyanate formed by reaction with 1,1,1-trimethylolpropane, or a biuret-type isocyanate formed by reaction with biuret. From the perspective of excellent reactivity with (meth)acrylic resins, the isocyanate compound may be an isocyanate having an aromatic ring.

[0090] When the (meth)acrylic resin is a (meth)acrylic polyol, the content of the isocyanate compound may be such that the number of OH groups of the acrylic polyol and the number of NCO groups of the isocyanate compound are equal.

[0091] To further enhance adhesion with the vapor-deposited layer 3, the anchor coating layer 2 may contain a silane coupling agent. Examples of such 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 may be used alone or in combination of two or more.

[0092] Alternatively, a polyurethane resin formed from an acid-group-containing polyurethane and a polyamine can be used as a material constituting the anchor coating layer 2. The polyurethane resin is obtained by bonding the acid groups of the acid-group-containing polyurethane to the amino groups of the polyamine serving as a crosslinking agent. In other words, the polyurethane resin can be considered a reactant of the acid-group-containing polyurethane and the polyamine, or a material formed by crosslinking the acid-group-containing polyurethane with the polyamine. The bond between the acid groups of the acid-group-containing polyurethane and the amino groups of the polyamine can 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).

[0093] Furthermore, a silane coupling agent or a carbodiimide compound may be added to the polyurethane resin. By adding such a compound, a cross-linked structure is formed with the polyurethane resin, thereby further improving the gas barrier properties or the adhesion between the substrate film 1 and the deposited layer 3. As the silane coupling agent, commonly used silane coupling agents can be used, for example, compounds having alkoxy groups and organic reactive groups bonded to silicon atoms.

[0094] The thickness of the anchor coating layer 2 is not particularly limited, as long as it improves the adhesion between the substrate film 1 and the deposited layer 3, but is preferably 30 nm or greater. In this case, compared to a case where the thickness of the anchor coating layer 2 is less than 30 nm, the surface smoothness of the anchor coating layer 2 can be further improved, the thickness of the deposited layer 3 can be made more uniform, and the oxygen barrier properties can be further improved. Therefore, the oxygen barrier properties of the gas barrier film 10 can be further improved. The thickness of the anchor coating layer 2 is more preferably 40 nm or greater, and even more preferably 50 nm or greater. Increasing the thickness of the anchor coating layer 2 can further suppress a decrease in gas barrier properties when external forces such as stretching are applied.

[0095] The thickness of the anchor coating layer 2 is preferably 2000 nm (2 μm) or less. In this case, the flexibility of the gas barrier film 10 is further improved compared to cases where the thickness of the anchor coating layer 2 exceeds 2000 nm, and the oxygen barrier properties of the gas barrier film 10 after rough treatment can be further improved. The thickness of the anchor coating layer 2 is more preferably 1500 nm (1.5 μm) or less.

[0096] The anchor coating layer 2 can be formed by, for example, applying an anchor coating solution on the resin layer by a method such as gravure coating, roll coating, or bar coating, and drying the solution.

[0097] To improve the adhesion between the base film 1 and the deposited layer 3, the surface of the base film 1 on which the 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 coating 2. Alternatively, the anchor coating 2 may be provided on the surface treated.

[0098] (Evaporated layer)

[0099] The deposited layer 3 contains an inorganic oxide. From the viewpoint of improving the gas barrier properties against water vapor, oxygen, etc., the deposited layer 3 may be formed directly on the anchor coating layer 2. The deposited layer 3 may be a transparent layer.

[0100] As the inorganic oxide, for example, aluminum oxide, silicon oxide, tin oxide, magnesium oxide, and mixtures thereof can be used. From the viewpoint of excellent sterilization resistance, the inorganic oxide may be at least one selected from aluminum oxide and silicon oxide.

[0101] From the perspective of achieving uniform film thickness and excellent gas barrier properties, the thickness of the deposited layer 3 may be 5 nm or more, 10 nm or more, or 15 nm or more. From the perspective of preventing cracks from occurring in the deposited layer 3 even when external force is applied after film formation, the thickness of the deposited layer 3 may be 300 nm or less, 150 nm or less, or 100 nm or less. From these perspectives, the thickness of the deposited layer 3 may be 5 to 300 nm, 10 to 150 nm, or 15 to 100 nm.

[0102] The deposited layer 3 can be formed, for example, by vacuum deposition, plasma-assisted deposition, ion beam-assisted deposition, sputtering, reactive deposition, or the like. From the perspective of excellent productivity, the deposited layer 3 can be formed by vacuum deposition. From the perspective of excellent adhesion between the deposited layer 3 and the substrate film 1 and improved density of the deposited layer 3, the deposited layer 3 can be formed by plasma-assisted deposition or ion beam-assisted deposition. From the perspective of excellent transparency of the deposited film, the deposited layer 3 can be formed by reactive deposition by blowing various gases such as oxygen.

[0103] Examples of heating methods for vacuum deposition include electron beam heating, resistance heating, and induction heating. Electron beam heating is preferred because it offers a wide range of selectivity for evaporation materials.

[0104] (Gas barrier coating layer)

[0105] The gas barrier film 10 may further include a gas barrier coating layer 4 on the side opposite to the anchor coating layer 2 relative to the deposited layer 3. The gas barrier film 10 including the gas barrier coating layer 4 protects the deposited layer 3 and further improves the gas barrier properties.

[0106] The gas barrier coating layer 4 may contain a silicon compound or its hydrolyzate and a water-soluble polymer having hydroxyl groups. Alternatively, the gas barrier coating layer 4 may contain a water-soluble polymer having hydroxyl groups and at least one selected from the group consisting of metal alkoxides, silane coupling agents, and their hydrolyzates.

[0107] The silicon compound may be, for example, selected from Si(OR 1 )4 and R 2 Si(OR 3 )3. OR 1 and OR 3 are each independently a hydrolyzable group, R 2 is an organic functional group. 2 , vinyl, epoxy, methacryloyloxy, urea, isocyanate, etc. can be listed. From the perspective of being relatively stable in aqueous solvents after hydrolysis, Si(OR 1 )4 can be tetraethoxysilane (Si(OC2H5)4).

[0108] Examples of the water-soluble polymer having a hydroxyl group include polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, etc. From the viewpoint of excellent gas barrier properties, the water-soluble polymer having a hydroxyl group may be polyvinyl alcohol.

[0109] Examples of the metal alkoxide include compounds represented by the following general formula (1).

[0110] M(OR 11 ) m (R 12 ) n－m (1)

[0111] In the above formula, R 11 and R 12 Each independently represents a monovalent organic group having 1 to 8 carbon atoms, preferably an alkyl group such as methyl or ethyl. 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 In the case of R 11 Between or R 12 They can be the same or different.

[0112] 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.

[0113] Examples of the silane coupling agent include compounds represented by the following general formula (2).

[0114] Si(OR 21 ) p (R 22 ) 3－p R 23 (2)

[0115] In the above formula, R 21 represents an alkyl group such as methyl or ethyl, 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 by an acryloyloxy group, or an alkyl group substituted by a methacryloyloxy group, and R 23 represents a monovalent organic functional group, and p represents an integer of 1 to 3. 21 or R 22 In the case of R 21 Between or R 22 They can be the same or different. 23 Examples of the monovalent organic functional groups include glycidyloxy, epoxy, mercapto, hydroxyl, amino, alkyl substituted with a halogen atom, and isocyanate. Compounds obtained by converting these silane coupling agents into multimers such as dimers and trimers may also be used.

[0116] 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.

[0117] 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 modifier, and a colorant.

[0118] The thickness of the gas barrier coating layer 4 may be 0.1 μm or 0.3 μm or more, 5 μm or 1 μm or less, 0.1 to 5 μm or 0.3 to 1 μm.

[0119] 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 a silicon compound or its hydrolyzate, a metal alkoxide, a silane coupling agent, etc., and applying the mixed solution on the vapor-deposited layer by gravure coating, roller coating, rod coating, etc., and drying it.

[0120] When the water-soluble polymer is polyvinyl alcohol, the content of polyvinyl alcohol in the mixed solution may be 20% or more, or 25% or more, based on the total solids content of the mixed solution, to facilitate formation of a gas barrier coating layer. From the perspective of excellent gas barrier properties, the content of polyvinyl alcohol in the mixed solution may be 50% or less, or 40% or less. The content of polyvinyl alcohol in the mixed solution may be 20-50% or 25-40% by mass, based on the total solids content of the mixed solution.

[0121] <Laminated body>

[0122] The laminate of 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. Furthermore, the laminate of this embodiment may further include a second substrate film made of polypropylene, disposed on the surface of the gas barrier film 10 opposite to the sealant layer.

[0123] Figure 3 This is a schematic cross-sectional view showing a laminated body according to one embodiment. Figure 3 The laminate 20 shown 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 .

[0124] Figure 4 This is a schematic cross-sectional view showing a laminated body according to another embodiment. Figure 4 The laminate 30 shown 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 resin film 22 made of polypropylene as a second base film is laminated on the gas barrier coating layer 4 of the gas barrier film 10 via an adhesive layer 24 .

[0125] For example, a stretched or unstretched polypropylene film can be used, or an unstretched polypropylene film can be used as the sealant layer 23. By using polypropylene as the material of the sealant layer 23, the laminate 20 can be made into a mono-material packaging material.

[0126] The thickness of the sealing layer 23 is not particularly limited, but may be, for example, 10 μm or more or 20 μm or more, or 200 μm or less or 100 μm or less. The thickness of the sealing layer 23 may be 10 to 200 μm or 20 to 100 μm.

[0127] The adhesive layer 24 is a layer that bonds the films together. Examples of adhesives that constitute the adhesive layer include polyurethane resins formed by reacting a difunctional or higher-functional isocyanate compound with a base such as polyester polyol, polyether polyol, acrylic polyol, or carbonate polyol. These polyols can be used alone or in combination of two or more.

[0128] From the viewpoint of improving 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 the above-mentioned polyurethane resin.

[0129] The coating amount of the adhesive layer may be, for example, 0.5 to 10 g / m2 from the viewpoint of obtaining desired adhesive strength, followability, and processability. 2 From an environmental perspective, the adhesive layer may be made of a biomass-derived polymer or a biodegradable adhesive. Furthermore, the adhesive layer may be made of an adhesive with barrier properties.

[0130] When the laminate further includes a resin film 22 as a second base film, the resin film 22 can 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 can be used.

[0131] 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.

[0132] Packaging materials

[0133] The packaging material can be made using the above-mentioned laminate. If the laminate using the above-mentioned gas barrier film, it is possible to make a packaging material that fully reduces the oxygen permeability even after a heat sterilization treatment such as a boiling treatment and has excellent lamination strength. In addition, if the laminate using the above-mentioned gas barrier film, it is possible to make a packaging material that suppresses the flavor degradation of the contents even after a heat sterilization treatment such as a boiling treatment. Therefore, the packaging material made from such a laminate can accommodate food, beverages, medicines, etc., and is particularly suitable for accommodating food and beverages. The laminate can be made into a bag-shaped packaging material (packaging bag) by folding a laminate in a manner where the sealing layers are opposite to each other and then heat-sealing the three sides other than the folded portion. It can also be made into a bag-shaped packaging material (packaging bag) by overlapping two laminates in a manner where the sealing layers are opposite to each other and then heat-sealing the four sides.

[0134] The packaging material may also have a spout. A packaging material with a spout may be secured by sandwiching the spout between two laminated sheets forming the packaging material, or by having a hole formed on one side of the packaging material and adhesively bonding a pouring spout. The pouring spout may be located on the top surface of the packaging material, or on the side, bottom, or diagonally above the packaging material. If the contents are liquid or gel, in addition to the spout (so-called suction nozzle), a straw that reaches the bottom of the packaging material may be provided to allow direct oral suction.

[0135] Another form of packaging material with a spout includes a bag-in-box (BIB) in which a bag (inner bag) containing liquids such as soft drinks and alcoholic beverages is housed in a paper box (outer box). Specifically, the laminate of this embodiment can be used in a BIB, particularly a bag equipped with a spout (tube) for pouring.

[0136] When the laminate is used as a packaging material with a spout, the spout portion and the entire spout of the lid may be formed of the same resin as the base film of the gas barrier film from the viewpoint of improving recyclability.

[0137] [Example]

[0138] Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to these Examples.

[0139] <Preparation of Anchor Coat Forming Composition>

[0140] The anchor coat forming composition was prepared as follows. γ-isocyanatepropyltrimethoxysilane and acrylic polyol were added to ethyl acetate as a diluent, and mixed and stirred. At this time, the acrylic polyol was added in a ratio of 5 parts by mass to 1 part by mass of γ-isocyanatepropyltrimethoxysilane. As the acrylic polyol, GS-5756 (trade name) manufactured by Mitsubishi Rayon Co., Ltd. was used. Next, toluene diisocyanate (TDI) as an isocyanate compound was added in such a manner that the NCO group became equal to the OH group of the acrylic polyol. The obtained mixed solution was diluted with the above-mentioned diluent to obtain a composition for forming an anchor coat having a solid content concentration of 2% by mass.

[0141] <Preparation of Composition for Forming Gas Barrier Coating Layer>

[0142] The following raw material liquid A, raw material liquid B, and raw material liquid C were mixed at a mass ratio of 0.5:0.4:0.1 to prepare a composition for forming a gas barrier coating layer.

[0143] (Raw material liquid A)

[0144] Polyvinyl alcohol (trade name "KURARAY POVAL 60-98", manufactured by Kuraray Co., Ltd.) was dissolved in water so that the solid content ratio became 5% by mass.

[0145] (Raw material liquid B)

[0146] 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.) are mixed in a mass ratio of 17 / 10 / 73 and dissolved in such a way that the solid content ratio becomes 5% by mass.

[0147] (Raw material liquid C)

[0148] 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 ratio became 5 mass %.

[0149] <Example 1>

[0150] (Production of Base Film)

[0151] First, the materials for each layer were melt-extruded using a screw extruder to produce a 1000 μm thick laminate film having a three-layer structure of first skin layer / core layer / second skin layer. Homopolypropylene was used as the core layer material, and an ethylene-propylene random copolymer with a melting point of 132°C (hereinafter referred to as "copolymer PP (1)") 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 anti-blocking agent (AB agent) in the amounts shown in Table 1.

[0152] Next, the laminated film was stretched 5 times in the machine direction (MD) and 10 times in the transverse direction (TD) using a tenter frame, and the surface on the first skin layer side was corona treated to obtain a simultaneously biaxially oriented polypropylene (PP) film with a thickness of 20 μm as a substrate film. The machine direction refers to the direction of melt extrusion, and the transverse direction refers to the direction perpendicular to the direction of melt extrusion. In the substrate film, the thickness of the first skin layer was 1 μm, the thickness of the core layer was 18 μm, and the thickness of the second skin layer was 1 μm. The surface of the substrate film on the first skin layer side was the first side on which the vapor-deposited layer was formed, and the surface on the second skin layer side was the second side.

[0153] (Production of Gas Barrier Film)

[0154] 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 thickness of 0.2 μm after drying, followed by drying at 60°C for 1 minute to form an anchor coat layer. Next, a 20 nm thick aluminum oxide vapor-deposited layer was formed on the anchor coat layer using a vacuum vapor deposition apparatus. Next, the gas barrier coating layer-forming composition prepared as described above was applied to the surface of the vapor-deposited layer using a bar coater to a thickness of 0.3 μm after drying, followed by drying in a 50°C oven for 1 minute to form a gas barrier coating layer. This produced a gas barrier film.

[0155] <Example 2>

[0156] 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 as an AB agent to the second skin layer in the amount shown in Table 1.

[0157] <Example 3>

[0158] A gas barrier film was 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 and PMMA particles (average particle size 4 μm) were further added as an AB agent to the second skin layer so as to have the content shown in Table 1.

[0159] <Example 4>

[0160] A gas barrier film was produced in the same manner as in Example 1 except that an ethylene-1-butene-1-propylene random copolymer having a melting point of 148° C. (hereinafter referred to as “copolymer PP (2)”) was used as the material for the first skin layer and the second skin layer.

[0161] <Example 5>

[0162] 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.

[0163] Comparative Example 1

[0164] A gas barrier film was 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.

[0165] Comparative Example 2

[0166] 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 as an AB agent to the second skin layer in the content shown in Table 1.

[0167] Comparative Examples 3 and 4

[0168] A gas barrier film was produced in the same manner as in Example 1, except that the synthetic silica particles were not added to the second skin layer and PMMA particles (average particle size 4 μm) were added in the amounts shown in Table 1.

[0169] <Examples 6 to 10 and Comparative Examples 5 to 8>

[0170] Gas barrier films of Examples 6 to 10 and Comparative Examples 5 to 8 were produced in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 4, except that synthetic silica particles (average particle size 2 μm) were added as an AB agent to the first skin layer in the amounts shown in Table 2.

[0171] <Examples 11 to 15 and Comparative Examples 9 to 12>

[0172] Gas barrier films of Examples 11 to 15 and Comparative Examples 9 to 12 were produced in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 4, except that acrylic resin particles (average particle size 2 μm) were added as an AB agent to the first skin layer in the amounts shown in Table 3.

[0173] <Measurement of Arithmetic Mean Altitude Sa>

[0174] The arithmetic mean heights Sa1 and Sa2 of the first skin layer-side surface and the second skin layer-side surface of the substrate films produced in 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 210 μm square measurement area. The results are shown in Tables 1 to 3.

[0175] [Preparation of Laminated Body A]

[0176] A 60 μm thick unstretched polypropylene film serving as a sealant layer was adhered to the surface (second surface) opposite to the gas barrier coating layer (second skin layer side) of the gas barrier films produced in the Examples and Comparative Examples by dry lamination using a two-component curable urethane adhesive. This produced a laminate A consisting of a gas barrier coating layer / evaporated layer / anchor coating layer / first skin layer / core layer / second skin layer / adhesive layer / sealant layer.

[0177] [Preparation of Laminated Body B]

[0178] The gas barrier coating layer-side surface (first surface) of the gas barrier films produced in the Examples and Comparative Examples was laminated to a 20 μm thick biaxially oriented polypropylene film (OPP) as a resin film via a two-component curable urethane adhesive by dry lamination. Subsequently, the second skin layer-side surface (second surface) of the gas barrier film was laminated to a 60 μm thick unoriented polypropylene film (CPP) as a sealant layer via a two-component curable urethane adhesive by dry lamination. This produced a laminate B consisting of resin film (OPP) / gas barrier coating layer / evaporated layer / anchor coating layer / first skin layer / core layer / second skin layer / adhesive layer / sealant layer (CPP).

[0179] [evaluate]

[0180] <Blocking resistance>

[0181] In the production of the above-mentioned gas barrier film, a sheet having an anchor coating layer and a vapor-deposited layer formed on the first epidermis layer of the substrate film is used as a test piece for evaluating blocking resistance. Two test pieces are prepared, and the surface of the vapor-deposited layer of one test piece is overlapped in such a manner as to face the surface of the other test piece on the opposite side of the vapor-deposited layer (the second epidermis layer side), a load of 1 MPa is applied, and the test pieces are placed under the conditions of 25°C and 65% RH for 24 hours. After placement, the overlapping test pieces are cut into a size of 150 mm in width and 500 mm in length, and the peel strength between the two test pieces is measured. The peel strength is measured using a TENSILON universal material testing machine (manufactured by A&D Co., Ltd., RTC-1250). The peel strength is used as an indicator of the blocking resistance of the substrate film and is evaluated based on the following evaluation criteria. The results are shown in Tables 1 to 3. If the result is "A", it can be said that the substrate film has excellent blocking resistance.

[0182] A: Peel strength is less than 0.5N / 150mm.

[0183] B: Peel strength is 0.5 N / 150 mm or more.

[0184] <Production of packaging bags>

[0185] A sheet of A4 size (long side 297 mm × short side 210 mm) is cut out from the laminate A produced above. The sheet is folded in half so that the short sides at both ends overlap each other, and the overlapping long sides are heat-sealed to produce a packaging bag (pouch) with an opening. Next, after 150 g of blanched minced chicken (containing 700 mg of amino acids per 100 g) is filled into the packaging bag as a content, the opening is heat-sealed to seal it. The sealed packaging bag is steamed to obtain a steamed packaging bag. The steaming treatment (steaming sterilization) is carried out by using a hot water storage type steamer at 120°C for 30 minutes.

[0186] <Measurement of oxygen transmission rate>

[0187] After retorting, the packaging bag was opened and a portion of the laminate A (100 mm x 100 mm) was cut out to serve as an evaluation sample. The oxygen transmission rate (OTR) of this cut sample was measured at 30°C and 70% RH using an oxygen transmission rate meter (trade name "OX-TRAN 2 / 20," manufactured by Modern Control). This measured value was used as an indicator of the oxygen barrier properties of the laminate A. The OTR was measured in accordance with JIS K7126-2. The OTR results are shown in Tables 1 to 3.

[0188] <Evaluation of flavor deterioration>

[0189] After retorting, the packaging bags were opened and four panelists conducted sensory evaluations based on the following criteria: the odor inside the packaging (presence of any foreign odors, such as retort flavor, other than the original flavor of the contents) and the flavor of the removed contents (presence of any deterioration from the original flavor of the contents). The average score was calculated. If the average score was 3.5 or higher, flavor degradation was considered suppressed. The results are shown in Tables 1 to 3.

[0190] (odor)

[0191] 5: Almost no odor is detected.

[0192] 4: There is a slight odor, but no problem.

[0193] 3: The odor is slightly strong, which may be a problem.

[0194] 2: Strong odor, there are problems.

[0195] 1: The odor is quite strong and there is a problem.

[0196] (smell)

[0197] 5: Feel the umami taste.

[0198] 4: The umami taste is slightly reduced, but there is no problem.

[0199] 3: There is no umami flavor, and the taste feels deteriorated, which is a problem.

[0200] 2: There is a problem with the deterioration of taste.

[0201] 1: Taste deterioration is significant and problematic.

[0202] <Adhesion strength after retort treatment>

[0203] The above-mentioned laminate B was used to make a packaging bag with four sides sealed, and water was filled as the content. After that, it was subjected to a retort sterilization treatment at 130°C for 30 minutes. The laminate B that had been subjected to the retort sterilization treatment was cut into a size of 150 mm in width and 500 mm in length, and the adhesion strength was measured. Regarding the adhesion strength, the adhesion strength between the biaxially oriented polypropylene film (OPP) and the first skin layer and the adhesion strength between the second skin layer and the unoriented polypropylene film (CPP) were measured. The results are shown in Tables 1 to 3.

[0204] [Table 1]

[0205]

[0206] [Table 2]

[0207]

[0208] [Table 3]

[0209]

[0210] Description of reference numerals:

[0211] 1: Base film; 2: Anchor coating layer; 3: Vapor-deposited layer; 4: Gas barrier coating layer; 10: Gas barrier film; 11: First skin layer; 12: Core layer; 13: Second skin layer; 20, 30: Laminated body; 22: Resin film; 23: Sealing layer; 24: Adhesive layer.

Claims

1. A gas barrier film, wherein The invention comprises: a base film comprising polypropylene; and a vapor-deposited layer comprising an inorganic oxide, wherein the vapor-deposited layer is disposed on a first surface which is one surface of the base film. The base film includes a second skin layer and a core layer, the second skin layer having a second surface which is a surface of the base film opposite to the first surface. The second skin layer contains silicon-containing particles at a ratio of 1500 mass ppm to 4000 mass ppm.

2. The gas barrier film according to claim 1, wherein The second skin layer further comprises an anti-blocking agent in addition to the silicon-containing particles.

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

4. The gas barrier film according to claim 1, wherein The base film includes a first skin layer, and the first skin layer has the first surface.

5. The gas barrier film according to claim 4, wherein The first skin layer comprises a copolymer of propylene and α-olefin, The arithmetic mean height Sa1 of the first surface of the base film is greater than or equal to 30 nm and less than or equal to 80 nm, and the arithmetic mean height Sa2 of the second surface is greater than or equal to 40 nm and less than or equal to 120 nm. The gas barrier film according to claim 5 , wherein The value of Sa1+Sa2 is 80 nm or more and 150 nm or less.

7. The gas barrier film according to claim 5, wherein The first skin layer comprises an anti-blocking agent.

8. The gas barrier film according to claim 1, wherein The evaporated layer includes aluminum oxide or silicon oxide.

9. The gas barrier film according to claim 1, wherein The gas barrier film further includes a gas barrier coating layer, and the gas barrier coating layer is disposed on a surface of the vapor-deposited layer opposite to the base film.

10. The gas barrier film according to claim 1, wherein The gas barrier film further includes an anchor coating layer, and the anchor coating layer is disposed between the base film and the vapor-deposited layer.

11. A laminated body, wherein: The invention comprises: the gas barrier film according to any one of claims 1 to 10; and a sealant layer disposed on the second skin layer side of the gas barrier film.

12. The laminate according to claim 11, wherein The laminate further includes a resin film made of polypropylene, and the resin film is disposed on the side of the gas barrier film opposite to the sealant layer.

13. A packaging bag formed by molding the laminate according to claim 11.

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