Base material film, gas barrier film, laminate, and packaging bag

Abstract

To provide a base material film capable of having excellent anti-blocking property even when wound in a roll state after forming a vapor deposition layer, and capable of obtaining good oxygen barrier property when forming a gas barrier film.SOLUTION: A base material film includes a polyolefin, where a first plane of one side surface includes 1-80 of particles having a particle size of 0.3 μm or more and less than 5 μm, and no particle having a particle size of 5 μm or more, and a second plane of a surface opposite side of the first plane includes 5 or more of particles having a particle size of 3 μm or more when measuring a number of particles existing on a surface of a measure area of 0.25 mm2 of the base material film by X-ray CT analysis.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] For packaging materials such as packaging bags used for packaging foods, pharmaceuticals, etc., in order to suppress the deterioration and spoilage of the contents and maintain their functions and qualities, a gas barrier property is required to prevent the entry of gases such as oxygen that can deteriorate the contents. Therefore, conventionally, films having a gas barrier property (gas barrier films) have been used for these packaging materials.

[0003] As such a gas barrier film, for example, a resin base material (base film) containing an antiblocking agent, an inorganic oxide layer, and an oxygen barrier film are provided in this order, and a gas barrier film is known in which the black area ratio on one surface of the resin base material is 0.15% or less (see Patent Document 1 below).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the gas barrier film described in Patent Document 1 above had room for improvement in terms of antiblocking properties when wound into a roll after forming the inorganic oxide layer (vapor deposition layer).

[0006] The present disclosure has been made in view of the above problems, and can have excellent blocking resistance even when wound into a roll after the formation of the vapor deposition layer, and can obtain good oxygen barrier properties when forming a gas barrier film. An object of the present disclosure is to provide a base film, a gas barrier film, a laminate, and a packaging bag using the same.

Means for Solving the Problems

[0007] In order to solve the above problems, the present disclosure provides the following base film, gas barrier film, laminate, and packaging bag. [1] A base film containing polyolefin, wherein when measuring the number of particles present on the surface of the base film with a measurement area of 0.25 mm 2 by X-ray CT analysis, one surface, the first surface, contains 1 to 80 particles with a particle diameter of 0.3 μm or more and less than 5 μm, and does not contain particles with a particle diameter of 5 μm or more, and the second surface, the surface opposite to the first surface, contains 5 or more particles with a particle diameter of 3 μm or more. [2] The base film according to [1] above, having a multilayer structure including at least two layers of a first skin layer having the first surface and a core layer. [3] The base film according to [2] above, further having a multilayer structure including a second skin layer having the second surface. [4] The base film according to [3] above, wherein the softening temperature of the second skin layer measured by local thermal analysis is 120°C or higher. [5] The base film according to any one of [2] to [4] above, wherein the first skin layer contains a copolymer of propylene and α-olefin. [6] A gas barrier film including the base film according to any one of [1] to [5] above and a vapor deposition layer containing an inorganic oxide disposed on the first surface of the base film. [7] The gas barrier film according to [6] above, wherein the inorganic oxide is aluminum oxide, silicon oxide, or a mixture thereof. [8] The gas-barrier film according to [6] or [7] above, further comprising a gas-barrier coating layer disposed on the surface of the vapor deposition layer opposite to the base film. [9] The gas-barrier film according to any one of [6] to [8] above, further comprising an anchor coat layer disposed between the base film and the vapor deposition layer.

[10] A laminate comprising the gas-barrier film according to any one of [6] to [9] above and a sealant layer, wherein the sealant layer contains polypropylene.

[11] The laminate according to

[10] above, further comprising a second base film on the surface of the gas-barrier film opposite to the sealant layer, wherein the second base film contains polypropylene.

[12] A packaging bag formed by bag-making the laminate according to

[10] or

[11] above.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to have excellent blocking resistance even when wound into a roll after the formation of the vapor deposition layer, and it is possible to obtain good oxygen barrier properties when forming the gas-barrier film. It is possible to provide a base film, a gas-barrier film, a laminate, and a packaging bag using the same.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

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

[0011] <Base film> The base film is a film (base film) that serves as a support in a gas barrier film and contains polyolefin. When the number of particles present on the measurement surface of 0.25 mm of the base film is measured by X-ray CT analysis, one surface, the first surface, contains 1 to 80 particles with a particle diameter of 0.3 μm or more and less than 5 μm, and does not contain particles with a particle diameter of 5 μm or more. The second surface, which is the surface opposite to the first surface, contains 5 or more particles with a particle diameter of 3 μm or more. 2 When the number of particles present on the surface of the other surface is measured, one surface, the first surface, contains 1 to 80 particles with a particle diameter of 0.3 μm or more and less than 5 μm, and does not contain particles with a particle diameter of 5 μm or more. The second surface, which is the surface opposite to the first surface, contains 5 or more particles with a particle diameter of 3 μm or more.

[0012] According to the above base film, by having the first surface and the second surface that satisfy the above-described conditions, even when a vapor deposition layer containing an inorganic oxide is formed on the first surface and then wound into a roll, excellent blocking resistance can be obtained, and good oxygen barrier properties can be obtained when forming a gas barrier film.

[0013] The base film may be formed by sheetifying a material containing polyolefin and stretching the sheet by ordinary means to form a film oriented uniaxially or biaxially.

[0014] The base film preferably contains polypropylene as the polyolefin. The polypropylene may be crystalline polypropylene. From the viewpoint of improving heat resistance, the polypropylene may be homopolypropylene, which is a homopolymer of propylene. The polypropylene may contain a copolymer of propylene and another monomer, or may contain a random copolymer of propylene and an α-olefin.

[0015] The polyolefin content 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 polyolefin 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 polyolefin).

[0016] The substrate film may contain organic additives such as antiblocking agents, antioxidants, stabilizers, lubricants, and antistatic agents, and may contain inorganic additives such as silica, zeolite, hydrotalcite, silicon particles, and siloid.

[0017] The thickness (total thickness) of the base film is not particularly limited, and may be, for example, from 10 μm to 200 μm, from 12 μm to 50 μm, or from 15 μm to 30 μm.

[0018] The polyolefin used in the substrate film may be a resin polymerized from fossil fuel, may be a recycled resin, or may be a resin obtained by polymerizing a raw material derived from biomass such as plants. When using these resins, they may be used alone, or may be used in combination with a resin polymerized from fossil fuel and a recycled resin or a resin obtained by polymerizing a raw material derived from biomass such as plants.

[0019] Particles are present on both surfaces of the substrate film. The number and size of the particles can be determined by X-ray CT analysis, which will be described later. Since the substrate film is generally used in the configuration of a laminate in which it is bonded to another film, the number and size of the particles on the substrate film surface can be measured by X-ray CT analysis of the cross section of the laminate. The shape of the particles is not particularly limited, and may be spherical, approximately spherical, blocky, flat, or the like.

[0020] 0.25 mm on the first surface of the base film (the surface on which the deposition layer is formed) 2When the number of particles per hit is measured by X-ray CT analysis, it contains 1 to 80 particles with a particle size of 0.3 μm or more and less than 5 μm, and does not contain particles with a particle size of 5 μm or more. Here, the particle size of the particle means the diameter (maximum diameter) of the longest part. When the number of particles with a particle size of 0.3 μm or more and less than 5 μm present on the first surface exceeds 80, or when particles with a particle size of 5 μm or more are present on the first surface, due to the excessive number of particles or the too large particle size, the unevenness of the surface of the first surface becomes large, and the vapor deposition layer formed on the first surface is likely to crack and the gas barrier property deteriorates. Also, when the number of particles with a particle size of 0.3 μm or more and less than 5 μm present on the first surface exceeds 80, or when particles with a particle size of 5 μm or more are present on the first surface, the haze may increase and the appearance of the base film may deteriorate. On the other hand, when the number of particles with a particle size of 0.3 μm or more and less than 5 μm present on the first surface is less than 1, the slipperiness of the film surface deteriorates, so the transportability during processing decreases, which may cause wrinkles and sagging in the film.

[0021] From the viewpoint of obtaining the above effects more sufficiently, the number of particles with a particle size of 0.3 μm or more and less than 5 μm present on the first surface of the base film is 0.25 mm 2 It is preferably 1.5 to 75 per hit, and more preferably 2 to 70.

[0022] Present on the second surface of the base film (the surface opposite to the side where the vapor deposition layer is formed), 0.25 mm 2When the number of particles per hit is measured by X-ray CT analysis, it contains 5 or more particles with a particle diameter of 3 μm or more. When the number of particles with a particle diameter of 3 μm or more present on the second surface is less than 5, the surface of the second surface becomes too smooth due to too few particles or too small particle diameters, and when a vapor deposition layer is formed on the first surface and winding is performed, the vapor deposition layer and the second surface adhere to each other and blocking occurs. When blocking occurs, when proceeding to the next process, problems such as the base film being easily cut and processing becoming difficult, or the wettability of the surface of the vapor deposition layer decreasing occur, leading to a decrease in the gas barrier property of the produced gas barrier film. In addition, when blocking occurs, a part of the additive (organic substance such as an antioxidant) in the second skin layer may migrate to the surface of the vapor deposition layer, causing a decrease in wettability.

[0023] From the viewpoint of obtaining the above effects more sufficiently, the number of particles with a particle diameter of 3 μm or more present on the second surface of the base film is 10 or more per 0.25 mm 2 and preferably 10 to 30. The upper limit value of the number of particles with a particle diameter of 3 μm or more present on the second surface is not particularly limited, but when it exceeds 30, the appearance of the base film deteriorates, which is not preferable. Also, when the particle diameter of the particles present on the second surface is larger than 12 μm, the appearance deteriorates or the particles are likely to fall off from the second surface. When a vapor deposition layer is formed on the first surface and winding is performed, the particles falling off from the second surface may adhere to the vapor deposition layer, which may lead to a decrease in the gas barrier property of the produced gas barrier film, so it is not preferable. Therefore, it is preferable that there are no particles with a particle diameter exceeding 12 μm on the second surface.

[0024] The second surface of the base film may contain particles with a particle diameter of less than 3 μm as long as the appearance and the performance of the film are not impaired.

[0025] When the base film contains an anti-blocking agent (hereinafter, also referred to as "AB agent"), the particles present on the first surface and the second surface of the base film may be particles provided due to the AB agent. Here, the AB agent itself may constitute the above particles.

[0026] The AB agent may be either organic particles or inorganic particles. Examples of the organic particles include polymethyl methacrylate particles, polystyrene particles, polyamide particles, and the like. Examples of the inorganic particles include silica particles, zeolite, talc, kaolinite, feldspar, and the like. Any one of these antiblocking agents may be used alone, or two or more thereof may be used in combination.

[0027] The base film may have a multilayer structure including at least two layers of a first skin layer having the first surface and a core layer, or may have a multilayer structure including at least three layers of a first skin layer having the first surface, a core layer, and a second skin layer having the second surface. The first skin layer and the second skin layer may be directly formed on the surface of the core layer. By providing the base film with the first skin layer, the stress applied to the vapor deposition layer due to the shrinkage of the base film after heat sterilization can be relaxed, and the destruction of the vapor deposition layer can be suppressed.

[0028] FIG. 1 is a schematic cross-sectional view showing a base film according to an embodiment. The base film shown in FIG. 1 has a three-layer structure 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. Note that the base film may have a two-layer structure of the first skin layer 11 and the core layer 12, or may have a multilayer structure of four or more layers further including other layers other than the first skin layer 11, the core layer 12, and the second skin layer 13. Further, the base film may have a single-layer structure in which the particle distribution is different between the first surface and the second surface.

[0029] (The first skin layer and the second skin layer) The first skin layer 11 and the second skin layer 13 contain polyolefin, and preferably contain polypropylene. The first skin layer 11 and the second skin layer 13 may contain homopolypropylene. Further, the first skin layer 11 and the second skin layer 13 may contain a copolymer of propylene and another monomer.

[0030] As other monomers used for the copolymer, for example, α-olefins such as ethylene, 1-butene, 1-hexene, etc. may be used. The first skin layer 11 and the second skin layer 13 may contain a copolymer of propylene and an α-olefin. The copolymer may be a random copolymer.

[0031] 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.

[0032] The polyolefin used for the first skin layer 11 and the second skin layer 13 may be a resin polymerized from fossil fuels, may be a recycled resin, or may be a resin obtained by polymerizing raw materials derived from biomass such as plants. When using these resins, they may be used alone, or a resin polymerized from fossil fuels may be mixed with a recycled resin or a resin obtained by polymerizing raw materials derived from biomass such as plants and used.

[0033] The first skin layer 11 and the second skin layer 13 may contain organic additives such as antiblocking agents, antioxidants, stabilizers, lubricants, antistatic agents, etc., and may also contain inorganic additives such as silica, zeolite, hydrotalcite, silicon particles, and siloid.

[0034] The first skin layer 11 and the second skin layer 13 can be formed on the core layer 12, for example, by coextruding the material forming the core layer 12 and the material forming the first skin layer 11 and the second skin layer 13. After coextrusion, the multilayer film may be stretched by ordinary means to obtain a uniaxially or biaxially oriented film.

[0035] The first skin layer 11 has a first surface F1, and the number of particles present on the first surface F1 satisfies the above-described conditions when measured by X-ray CT analysis. From the viewpoints of having the first surface F1 that satisfies the above-described conditions and anti-blocking performance, the first skin layer 11 preferably contains an AB agent having an average particle diameter of 0.1 to 5 μm, and more preferably contains an AB agent having an average particle diameter of 0.5 to 3 μm. In this specification, the average particle diameter is the weight average diameter measured by the Coulter method. Further, from the viewpoint of having the first surface F1 that satisfies the above-described conditions, the content of the AB agent in the first skin layer 11 is preferably 50 to 1500 mass ppm, and more preferably 100 to 1000 mass ppm.

[0036] The second skin layer 13 has a second surface F2, and the number of particles present on the second surface F2 satisfies the above-described conditions when measured by X-ray CT analysis. From the viewpoints of having the second surface F2 that satisfies the above-described conditions and anti-blocking performance, the second skin layer 13 preferably contains an AB agent having an average particle diameter of 1 to 10 μm, and more preferably contains an AB agent having an average particle diameter of 3 to 7 μm. Further, from the viewpoint of having the second surface F2 that satisfies the above-described conditions, the content of the AB agent in the second skin layer 13 is preferably 500 to 5000 mass ppm, and more preferably 1000 to 4000 mass ppm.

[0037] From the viewpoint of more sufficiently obtaining the effects of the present disclosure, the average particle diameter of the AB agent in the second skin layer 13 may be 1.2 times or more, and may be 1.5 times or more, the average particle diameter of the AB agent in the first skin layer 11.

[0038] From the viewpoint of more sufficiently obtaining the effects of the present disclosure, the content of the AB agent in the second skin layer 13 may be 1.0 times or more, and may be 1.2 times or more, the content of the AB agent in the first skin layer 11.

[0039] The thickness of the 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 obtaining good barrier properties without lowering the heat resistance of the base film.

[0040] The thickness of the second skin layer 13 is preferably 0.1 to 2.0 μm, more preferably 0.3 to 1.5 μm, from the viewpoint of maintaining a certain level of adhesion strength without degrading the heat resistance of the base film.

[0041] The second skin layer 13 preferably has a softening temperature of 120°C or higher as measured from the film cross-section by local thermal analysis (LTA). When a vapor deposition layer is formed on the first surface F1 and winding is performed, if the softening temperature of the second skin layer 13 is 120°C or higher, blocking between the vapor deposition layer and the second skin layer 13 can be suppressed, and the breakage of the base film 1 can be suppressed. The upper limit value of the softening temperature of the second skin layer 13 is not particularly limited. However, if the softening temperature exceeds 170°C, the flexibility of the second skin layer 13 may decrease, and the adhesion strength with the core layer 12 may decrease. Therefore, the softening temperature of the second skin layer 13 is preferably 170°C or lower. The measured temperature at the center of the second skin layer 13 is used as the softening temperature.

[0042] (Core layer) The core layer 12 contains a polyolefin, and preferably contains polypropylene as the polyolefin. From the viewpoint of enhancing the heat resistance of the base film 1, the polypropylene used in the core layer 12 may be crystalline polypropylene, and from the viewpoint of further improving the heat resistance for heat sterilization treatment, it may be homopolypropylene which is a homopolymer of propylene. However, within the range that does not significantly impair the effects of the present disclosure, a random copolymer of propylene and an α-olefin, or a mixture of the copolymer and homopolypropylene, etc. may be used.

[0043] The polyolefin used in the core layer 12 may be a resin polymerized from fossil fuels, may be a recycled resin, or may be a resin obtained by polymerizing a raw material derived from biomass such as plants. When using these resins, they may be used alone, or a resin polymerized from fossil fuels may be mixed with a recycled resin or a resin obtained by polymerizing a raw material derived from biomass such as plants and used.

[0044] When the base film 1 includes the first skin layer 11 and the second skin layer 13, the core layer 12 disposed between the first skin layer 11 and the second skin layer 13 may not contain AB agent.

[0045] From the viewpoint of maintaining the processability and ease of handling as a base film, the thickness of the core layer 12 may be 10 to 200 μm, 12 to 50 μm, or 15 to 30 μm.

[0046] 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) may be 1 / 100 to 1 / 5, or may be 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 enhanced.

[0047] The ratio of the thickness of the second skin layer 13 to the thickness of the core layer 12 (thickness of the second skin layer 13 / thickness of the core layer 12) may be 1 / 100 to 1 / 5, or may be 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 enhanced.

[0048] <Gas barrier film> Figure 2 is a schematic cross-sectional view showing a gas barrier film according to an embodiment. As shown in Figure 2, the gas barrier film 10 according to this embodiment includes a base film 1, an anchor coat layer, a vapor deposition layer 3, and a gas barrier coating layer 4 in this order. As the base film 1, the base film of the present disclosure described above is used. The anchor coat layer 2 is disposed on the surface of the base film 1 on the side of the first skin layer 11.

[0049] (Anchor coat layer) The anchor coat layer 2 is a layer for further improving the adhesion between the base film 1 and the vapor deposition layer 3, and is provided between the base film 1 and the vapor deposition layer 3. The material constituting the anchor coat layer 2 is not particularly limited as long as it can improve the adhesion between the base film 1 and the vapor deposition layer 3.

[0050] As the material of the anchor coat layer 2, for example, a material containing a reaction product of a polyol compound containing a (meth)acrylic resin and an isocyanate compound can be used. Note that the “(meth)acrylic resin” means at least one of “acrylic resin” and the corresponding “methacrylic resin”.

[0051] Examples of the (meth)acrylic resin 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 the (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 the isocyanate compound used as a curing agent described later, the (meth)acrylic resin may be a polyol having two or more hydroxyl groups in one molecule, and particularly may be a (meth)acrylic polyol.

[0052] The (meth)acrylic polyol may be a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon-based (meth)acrylate and a hydroxyl group-containing monomer, or a (meth)acrylic copolymer obtained by copolymerizing a hydrocarbon-based (meth)acrylate, a hydroxyl group-containing monomer, and other monomer components (other monomer components). By copolymerizing the above monomers, a (meth)acrylic polyol containing a plurality of hydroxyl groups can be obtained.

[0053] The anchor coat layer 2 may contain a curing agent. As the curing agent, from the viewpoint of excellent reactivity with the (meth)acrylic resin, an isocyanate-based compound having two or more NCO groups in the molecule may be used.

[0054] The isocyanate compound may be a monomeric isocyanate. Examples of monomeric isocyanates include aromatic or araliphatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI); aliphatic isocyanates such as hexamethylene diisocyanate (HDI), bis(isocyanatomethyl)cyclohexane (H6XDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (H12MDI), and the like.

[0055] The isocyanate-based compound may be a polymer or derivative of the above monomeric isocyanate. The isocyanate compound may be, for example, an isocyanate having a structure such as a trimeric nurate type, an adduct type reacted with 1,1,1-trimethylolpropane or the like, 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.

[0056] 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 of the acrylic polyol is equal to the number of NCO groups of the isocyanate compound.

[0057] From the perspective of further improving the adhesion with the vapor deposition layer 3, the anchor coat layer 2 may contain a silane coupling agent. Examples of the silane coupling agent 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-isocyanatopropyltriethoxysilane. These silane coupling agents can be used alone or in combination of two or more kinds.

[0058] In addition, as a material constituting the anchor coat layer 2, a polyurethane resin formed from an acid group-containing polyurethane and a polyamine can also be used. The polyurethane resin is obtained by bonding the acid group of the acid group-containing polyurethane and the amino group of the polyamine as a crosslinking agent. That is, the polyurethane resin can be said to be a reaction product of an acid group-containing polyurethane and a polyamine, or a product in which an acid group-containing polyurethane is crosslinked by a 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 (for example, an ionic bond between a carboxyl group and a tertiary amino group) or a covalent bond (for example, an amide bond or the like).

[0059] Further, a silane coupling agent or a carbodiimide compound may be added to the above polyurethane resin. By adding such a compound, a crosslinked structure is formed with the polyurethane resin, and the gas barrier property or the adhesion between the base film 1 and the vapor deposition layer 3 can be further improved. As the silane coupling agent, those generally used can be used, for example, compounds in which an alkoxy group and an organic reaction group are bonded to a silicon atom.

[0060] The thickness of the anchor coat layer 2 is not particularly limited as long as it can improve the adhesion between the base film 1 and the vapor deposition layer 3, but is preferably 30 nm or more. In this case, compared with the case where the thickness of the anchor coat layer 2 is less than 30 nm, the smoothness of the surface of the anchor coat layer 2 can be further improved, the thickness of the vapor deposition layer 3 can be made more uniform, and the oxygen barrier property can also be further improved. Therefore, the oxygen barrier property of the gas barrier film 10 can be further improved. 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 a decrease in the gas barrier property when an external force such as stretching is applied.

[0061] The thickness of the anchor coat layer 2 is preferably 2000 nm (2 μm) or less. In this case, compared with the case where the thickness of the anchor coat layer 2 exceeds 2000 nm, the flexibility of the gas barrier film 10 is further improved, and the oxygen gas barrier property of the gas barrier film 10 after abuse can be further improved. The thickness of the anchor coat layer 2 is more preferably 1500 nm (1.5 μm) or less.

[0062] The anchor coat layer 2 can be formed, for example, by applying an anchor coat solution onto a resin layer by a method such as gravure coating, roll coating, or bar coating and then drying it.

[0063] In order to improve the adhesion between the base film 1 and the vapor deposition layer 3, instead of the anchor coat layer 2, a surface treatment such as plasma treatment or corona treatment may be performed on the surface of the base film 1 on the side where the vapor deposition layer 3 is formed. Further, an anchor coat layer 2 may be provided on the surface that has been surface-treated.

[0064] (Vapor deposition layer) The vapor deposition layer 3 contains an inorganic oxide. The vapor deposition layer 3 may be formed directly on the anchor coat layer 2 from the viewpoint of improving the gas barrier property against water vapor, oxygen, etc. The vapor deposition layer 3 may have transparency.

[0065] As the inorganic oxide, for example, aluminum oxide, silicon oxide, tin oxide, magnesium oxide, and a mixture thereof can be used. From the viewpoint of excellent bactericidal resistance, the inorganic oxide may be at least one selected from aluminum oxide and silicon oxide.

[0066] From the viewpoint that the thickness of the vapor deposition layer 3 becomes uniform and the gas barrier property is excellent, it may be 5 nm or more, 10 nm or more, or 15 nm or more, and from the viewpoint that cracks are less likely to occur in the vapor deposition layer 3 even when an external force is applied after film formation, it may be 300 nm or less, 150 nm or less, or 100 nm or less. From these viewpoints, the thickness of the vapor deposition layer 3 may be 5 to 300 nm, 10 to 150 nm, or 15 to 100 nm.

[0067] The vapor deposition layer 3 can be formed, for example, by a vacuum evaporation method, a plasma assist method, an ion beam assist method, a sputtering method, a reactive evaporation method, or the like. From the viewpoint of excellent productivity, the vapor deposition layer 3 may be formed by a vacuum evaporation method, and from the viewpoints of excellent adhesion between the vapor deposition layer 3 and the base film 1 and improving the denseness of the vapor deposition layer 3, it may be formed by a plasma assist method or an ion beam assist method, and from the viewpoint of excellent transparency of the vapor deposition film, it may be formed by a reactive evaporation method in which various gases such as oxygen are blown in.

[0068] Examples of the heating means of the vacuum evaporation method include an electron beam heating method, a resistance heating method, and an induction heating method. The heating means of the vacuum evaporation method may be an electron beam heating method from the viewpoint of excellent selectivity of the evaporation material.

[0069] (Gas barrier coating layer) The gas barrier film 10 may further include a gas barrier coating layer 4 on the side opposite to the anchor coat layer 2 with respect to the vapor deposition layer 3. By providing the gas barrier film 10 with the gas barrier coating layer 4, the vapor deposition layer 3 can be protected and the gas barrier property can be further improved.

[0070] The gas barrier coating layer 4 may contain a silicon compound or its hydrolyzate and a water-soluble polymer having a hydroxyl group.

[0071] Examples of the silicon compound include at least one selected from 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. Examples of R 2 include a vinyl group, an epoxy group, a methacryloxy group, a ureido group, an isocyanate group, etc. From the viewpoint of being relatively stable in an aqueous solvent after hydrolysis, Si(OR 1 )4 may be tetraethoxysilane (Si(OC2H5)4).

[0072] 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.

[0073] 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, a colorant, etc.

[0074] The thickness of the gas barrier coating layer 4 may be 0.1 μm or more or 0.3 μm or more, and may be 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.

[0075] For example, the gas barrier coating layer 4 can be formed by dissolving a water-soluble polymer in water or a water / alcohol mixed solvent, then mixing a silicon compound or its hydrolyzate, and applying this mixed solution onto the vapor deposition layer by methods such as gravure coating, roll coating, bar coating, etc., and drying it.

[0076] 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 easily forming the gas barrier coating layer, and may be 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.

[0077] <Laminate> The laminate according to the present embodiment includes the above-described gas barrier film 10 and a sealant layer containing polypropylene disposed on at least one surface of the gas barrier film 10. Further, the laminate according to the present embodiment may further include a second base film containing polypropylene disposed on the surface of the gas barrier film 10 opposite to the sealant layer.

[0078] FIG. 3 is a schematic cross-sectional view showing a laminate according to an embodiment. The laminate 20 shown in FIG. 3 has a structure in which a second base film 22 containing polypropylene is laminated on the gas barrier coating layer 4 of the gas barrier film 10 via an adhesive layer 24, and a sealant layer 23 containing polypropylene is laminated on the second skin layer 13 of the gas barrier film 10 via the adhesive layer 24. By using polypropylene as the material of the base film 1, the laminate 20 can be a monomaterial packaging material.

[0079] As the second base film 22, for example, a film obtained by stretching homopolypropylene may be used to provide heat resistance.

[0080] As the sealant layer 23, for example, a stretched or unstretched polypropylene film may be used, or an unstretched polypropylene film may be used.

[0081] The thickness of the second base film 22 is not particularly limited, and may be, for example, 3 μm or more and 200 μm or less, or may be 6 μm or more and 50 μm or less.

[0082] The thickness of the sealant layer 23 is not particularly limited, and may be, for example, 10 μm or more or 20 μm or more, and may be 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.

[0083] The adhesive layer 24 adheres the films to each other. Examples of the adhesive constituting the adhesive layer include polyurethane resins obtained by reacting a bifunctional or higher isocyanate compound with a main agent such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol. Various polyols may be used alone or in combination of two or more.

[0084] 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, etc. in the above-mentioned polyurethane resin.

[0085] The coating amount of the adhesive layer may be, for example, 0.5 to 10 g / m 2 from the viewpoint of obtaining desired adhesive strength, followability, processability, etc. For the adhesive layer, those having a polymer component derived from biomass or those having biodegradability may be used from the viewpoint of environmental consideration. Also, an adhesive having barrier properties may be used for the adhesive layer.

[0086] <Packaging material> The packaging material can be produced using the above-described laminate. In the case of a laminate using the above gas barrier film, it is possible to produce a packaging material having a sufficiently low oxygen transmission rate and excellent laminate strength even after heat sterilization treatment. Therefore, a packaging material produced from such a laminate can contain foods, pharmaceuticals, and the like. The laminate may be formed 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 three sides other than the folded portion, or by stacking two laminates so that the sealant layers face each other and then heat-sealing four sides.

[0087] The packaging material may be provided with a stopper. For the packaging material with a stopper, the stopper may be sandwiched and fixed between two laminates forming the packaging material, or a hole may be made in one side of the packaging material and a spout may be adhered and fixed. The spout may be provided on the upper surface of the packaging material, or may be provided on the side surface, bottom surface, or obliquely upward of the packaging material. When the content is liquid or gel-like, in addition to a spout (so-called pour spout) that can be directly put into the mouth and sucked out, a straw reaching the bottom of the packaging material may be provided.

[0088] Another form of the packaging material with a stopper is a bag-in-box in which a bag (inner bag) containing a liquid such as a soft drink or an alcoholic beverage is housed in a carton (outer box). That is, the laminate according to the present embodiment can be used for the bag of the bag-in-box, particularly for a bag provided with a pour spout (tube).

[0089] When the laminate is used as a packaging material with a stopper, from the viewpoint of improving recyclability, the stopper portion and the entire stopper of the cap may be formed of the same resin as the base film of the gas barrier film.

Examples

[0090] Hereinafter, the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited to these examples.

[0091] <Preparation of the Composition for Forming the Anchor Coat Layer> An acrylic polyol and tolylene diisocyanate were mixed such that the number of NCO groups of tolylene diisocyanate was equal to the number of OH groups of the acrylic polyol, and the mixture was diluted with ethyl acetate so that the solid content (total amount of the acrylic polyol and tolylene diisocyanate) became 5% by mass. To the diluted mixture, β-(3,4-epoxycyclohexyl)trimethoxysilane was further added in an amount of 5 parts by mass with respect to 100 parts by mass of the total amount of the acrylic polyol and tolylene diisocyanate, and these were mixed to prepare a composition for forming an anchor coat layer.

[0092] <Example 1> First, a laminated film having a three-layer structure of a first skin layer / core layer / second skin layer with a thickness of 1000 μm was produced by melt-extruding the materials of each layer using a screw extruder. At this time, homopolypropylene was used as the material for the first skin layer, the core layer, and the second skin layer. In the first skin layer and the second skin layer, a masterbatch containing polymethyl methacrylate (PMMA) particles with an average particle diameter of 2 μm or silica particles with an average particle diameter of 5 μm as an antiblocking agent (AB agent) was added so that the addition amount of the particles was the addition amount shown in Table 1.

[0093] Next, the above laminated film was stretched 5 times in the longitudinal direction (MD) and 10 times in the transverse direction (TD) using a tenter to obtain a biaxially oriented polypropylene (PP) film with a thickness of 20 μm. The longitudinal direction is the direction of melt extrusion, and the transverse direction is the direction perpendicular to the direction of melt extrusion.

[0094] Next, the surface on the first skin layer side of the obtained PP film was subjected to corona treatment. At this time, the surface subjected to corona treatment was defined as the first surface, and the surface on the opposite side of the first surface (the surface on the second skin layer side of the PP film) was defined as the second surface. The PP film thus produced was used as a base film. The thickness of the first skin layer of the base film was 0.8 μm, the thickness of the core layer was 18.5 μm, and the thickness of the second skin layer was 0.7 μm.

[0095] Subsequently, a composition for forming an anchor coat layer was applied onto the first surface of the base film by gravure coating and dried in an oven at 100°C for 10 seconds to form an anchor coat layer with a thickness of 0.12 μm.

[0096] Next, silicon oxide was deposited by reactive evaporation by high-frequency excited ion plating in an oxygen atmosphere under reduced pressure onto the anchor coat layer to form a vapor deposition layer of inorganic oxide with a thickness of 30 nm.

[0097] Next, a solution obtained by mixing the following Liquid A, Liquid B, and Liquid C at a mixing ratio (mass ratio) of 70 / 20 / 10 was applied onto the vapor deposition layer by the gravure coating method and dried under the conditions of 80°C for 20 seconds to form a gas barrier coating layer with a thickness of 0.3 μm. Thereby, a gas barrier film was obtained. Liquid A: A hydrolysis solution (solid content 5 mass% (in terms of SiO2)) obtained by adding 72.1 g of hydrochloric acid (0.1 N) to a mixed solution of 17.9 g of tetraethoxysilane and 10 g of methanol and stirring for 30 minutes for hydrolysis. Liquid B: A water / methanol solution (water / methanol mass ratio = 95 / 5) containing 5 mass% of polyvinyl alcohol. Liquid C: A hydrolysis solution (solid content 5 mass% (in terms of R 2 Si(OH)3 conversion)) obtained by gradually adding hydrochloric acid (1 N) to a mixed solution of β-(3,4-epoxycyclohexyl)trimethoxysilane and isopropyl alcohol (IPA solution), stirring for 30 minutes, and hydrolyzing with a water / IPA solution (water / IPA mass ratio = 1 / 1).

[0098] <Examples 2 to 3> A gas barrier film was produced in the same manner as in Example 1, except that the types, average particle diameters, and addition amounts of the AB agents in the first skin layer and the second skin layer were changed as shown in Table 1.

[0099] <Example 4> The 1-butene-propylene random copolymer resin (1-butene content: 4 mol%) (hereinafter referred to as "copolymer PP(1)") was used for the second skin layer, and a gas barrier film was produced in the same manner as in Example 1 except that the types, average particle diameters, and addition amounts of the AB agents in the first skin layer and the second skin layer were changed as shown in Table 1.

[0100] <Example 5> The ethylene-1-butene-propylene random copolymer resin (ethylene content: 2.5 mol%, 1-butene content: 3.5 mol%) (hereinafter referred to as "copolymer PP(2)") was used for the first skin layer, copolymer PP(1) was used for the second skin layer, and a gas barrier film was produced in the same manner as in Example 1 except that the types, average particle diameters, and addition amounts of the AB agents in the first skin layer and the second skin layer were changed as shown in Table 1.

[0101] <Example 6> Copolymer PP(2) was used for the first skin layer, and the ethylene-propylene random copolymer resin (ethylene content: 10 mol%) (hereinafter referred to as "copolymer PP(3)") was used for the second skin layer. A gas barrier film was produced in the same manner as in Example 1 except that the types, average particle diameters, and addition amounts of the AB agents in the first skin layer and the second skin layer were changed as shown in Table 1.

[0102] <Comparative Example 1> A gas barrier film was produced in the same manner as in Example 1 except that no AB agent was added to the first skin layer.

[0103] <Comparative Example 2> Copolymer PP(2) was used for the first skin layer, and a gas barrier film was produced in the same manner as in Example 1 except that the types, average particle diameters, and addition amounts of the AB agents in the second skin layer were changed as shown in Table 2.

[0104] <Comparative Examples 3 - 4> A gas barrier film was produced in the same manner as in Example 1, except that the types, average particle diameters, and addition amounts of the AB agents in the first skin layer and the second skin layer were changed as shown in Table 2.

[0105] [Production of laminate] On the surface of the gas barrier film on the gas barrier coating layer side produced in the examples and comparative examples, a biaxially stretched polypropylene film with a thickness of 20 μm as the second base film, and on the surface on the base film side, an unstretched polypropylene film with a thickness of 60 μm as the sealant layer were each laminated by the dry lamination method via a two-component curable urethane-based adhesive to produce a laminate composed of a second base film / adhesive layer / gas barrier film / adhesive layer / sealant layer.

[0106] [Evaluation] <Cross-section processing method for samples for X-ray CT analysis and softening temperature measurement> Using the laminates produced using the gas barrier films of the examples and comparative examples as samples, the front and back surfaces of these samples were each subjected to corona treatment at 0.20 kW. A corona treatment machine (product name: CT-0212) manufactured by Kasuga Electric Co., Ltd. was used for the corona treatment.

[0107] After corona treatment, the sample was cut with scissors into a strip shape with a base of 1.0 mm × a height of 5.0 mm to obtain cut pieces. The cut pieces were embedded in a photocurable resin, and the photocurable resin was cured with a halogen lamp (manufactured by Kenko Tokina Co., Ltd., product name: KTX-100R) to obtain block pieces. D-800 (product name) manufactured by Toagosei Co., Ltd. was used as the photocurable resin. The block pieces after photocuring were fixed with an insert for an AFM sample holder, and at room temperature (25°C), the cross-section of the sample was cut with a glass knife using a cross-section cutting device. After that, at a low temperature (-40°C), final cross-section cutting was carried out using a diamond knife with a cutting speed of 1.0 mm / s and a cutting film thickness of 100 nm using a cross-section cutting device, and the cutting was terminated when a mirror surface was obtained, and a measurement sample with the cross-section of the laminate exposed was obtained. As the cross-section cutting device, an ultramicrotome (manufactured by Leica Microsystems, product name: EM UC7) and a cryo system (manufactured by Leica Microsystems, product name: EM FC7) were used. Also, the cutting direction of the knife was parallel to the interface with the adjacent layer and perpendicular to the long side of the strip-shaped cut piece. The measurement sample was used for X-ray CT analysis and softening temperature measurement while being fixed with an insert for an AFM sample holder.

[0108] <X-ray CT Analysis Method> The measurement sample prepared above was fixed to a holder, and continuous transmission images were taken by X-ray CT (1601 images were taken for 0° to 360°). Next, based on all the obtained transmission images, reconstruction was performed to create tomographic images, and three-dimensional reconstructed images (TIF stack images) and reconstructed cross-sectional images (3-view images) were created using dedicated software. The analyzer and measurement conditions are described below. Regarding the obtained continuous transmission images, observation was performed from the surface side of the second base film, and the number of particles on the first and second surfaces of the base film in the gas barrier film was counted. The imaging was performed in 4 fields of view with an area of 0.25 mm square, and the total count was taken as the number of particles. The reconstructed cross-sectional image (3-view image) when measuring the number of particles on the first surface of the base film of Example 1 is shown in FIG. 4. (Analyzer and Measurement Conditions) X-ray CT: Manufactured by Zeiss, product name "Xradia 620 Versa", tube voltage 80 kV Pixel size: 0.3 μm / pixel Analysis software: ImageJ

[0109] <Measurement of softening temperature> Using MFP-3D-SA (trade name) manufactured by Oxford Instruments Co., Ltd. as an atomic force microscope (AFM), Ztherm system (trade name) as a local thermal analysis option, and AN2-200 (trade name) manufactured by Anasis Instruments with a spring constant specification of 0.5 to 3.5 N / m as a cantilever, the softening temperature measurement and shape measurement were performed on the measurement sample prepared above. The softening temperature measurement was performed at the center in the thickness direction of the second skin layer of the base film.

[0110] At this time, with the contact pressure of the cantilever (change in the deflection amount of the cantilever) being 0.2 V, the voltage application acceleration (heating rate) being 0.5 V / second, and the maximum applied voltage being 5.5 V, when the sample surface was heated after Detrend correction, the sample surface expanded and the cantilever position rose. When the sample surface was further heated, the sample surface softened and the cantilever position dropped. The measurement was terminated when the cantilever dropped by 10 nm. When the Z displacement did not drop by 10 nm from the change point and reached the maximum applied voltage, the maximum applied voltage at the time of Detrend correction and measurement was increased by 0.5 V and the measurement was performed again.

[0111] The applied voltage at the point where the height (Z displacement) in the vertical direction of the cantilever was maximum was taken as the applied voltage at the softening point, and the voltage value was read.

[0112] To calculate the softening temperature of the sample, a calibration curve was created according to the measurement conditions. As calibration samples, the following four types of polymer materials whose melting points (melting peak temperatures) were measured in advance by a differential scanning calorimeter (DSC) were used, and cross-section samples prepared in an environment below the glass transition temperature were used respectively. · Polycaprolactone pellets (melting point: 60 °C) · Low-density polyethylene pellets (melting point: 112 °C) · Polypropylene pellets (melting point: 166 °C) · Biaxially oriented polyethylene terephthalate film (melting point: 255 °C) For the preparation of cross-sectional samples, an ultramicrotome and a cryo system were used. Cross-sectional cutting was performed on polycaprolactone at -80 °C, low-density polyethylene at -140 °C, polypropylene at -40 °C, and polyethylene terephthalate at room temperature of 25 °C. The measurement conditions were as follows: the voltage application acceleration (heating rate) was 0.5 V / second, and the maximum applied voltage was 3.5 V for polycaprolactone, 5 V for low-density polyethylene, 6 V for polypropylene, and 7.8 V for polyethylene terephthalate. The contact pressure of the cantilever (change in the deflection amount of the cantilever) was set to 0.2 V in the calibration curve of the second skin layer of the base film. After Detrend correction, the sample surface was heated to measure the applied voltage at the softening point. The applied voltage at the softening point was measured 10 times by changing the measurement position of the calibration sample, and a calibration curve was created by approximating the average value of the applied voltage at the softening point and the melting point (melting peak temperature) of the DSC measurement with a cubic function by the least squares method.

[0113] Using the calibration curve of the applied voltage and temperature, the temperature corresponding to the applied voltage at the softening point of the second skin layer of the base film was obtained respectively, and this temperature was defined as the softening temperature. The results are shown in Table 1 and Table 2.

[0114] <Evaluation of wettability> After forming the vapor deposition layer (before forming the gas barrier coating layer) of the gas barrier films in the examples and comparative examples, two A4-sized sheets were cut out from the film. The two sheets were overlapped so that the surface of the vapor deposition layer and the second surface of the base film faced each other to obtain a structure. This structure was stored for 8 hours while being pressurized under the conditions of a pressure of 4 MPa, 25 °C, and 65% RH using a press machine (manufactured by Kitakawa Seiki Co., Ltd., product name: KVHC-II). Then, the two sheets were separated, and the wetting surface tension, which is an index of the wettability of the surface of the vapor deposition layer, was measured in accordance with JIS K6768. This measured value was used as an index of wettability. The wettability was judged based on the following criteria. The results are shown in Table 1 and Table 2. A: Wetting surface tension of 35 mN / m or more B: Wetting surface tension less than 35 mN / m

[0115] <Evaluation of blocking resistance> After the vapor deposition layer of the gas barrier films of the examples and comparative examples was formed (before the gas barrier coating layer was formed), two films were prepared. The two films were overlapped so that the surface of the vapor deposition layer and the second surface of the base film faced each other, a load of 1 MPa was applied, and they were left for 24 hours under the conditions of 25 °C and 65% RH. After leaving, the film in the overlapped state was cut out into a size of 150 mm in width × 500 mm in length, and the peeling strength when peeling the two films was measured. The peeling strength was measured using a tensilon universal testing machine RTC-1250 manufactured by Orientec Co., Ltd. at a peeling speed of 300 mm / min and a peeling angle of T-type. This peeling strength was used as an index of blocking resistance. The smaller the peeling strength, the better the blocking resistance. The blocking resistance was judged based on the following criteria. If the judgment result was A or B, it was judged that the base film had excellent blocking resistance even when it was wound up in a roll after the vapor deposition layer was formed. The results are shown in Tables 1 and 2. A: Peel strength less than 0.2 N / 150 mm B: Peel strength of 0.2 N / 150 mm or more and less than 0.5 N / 150 mm C: Peel strength of 0.5 N / 150 mm or more

[0116] <Measurement of oxygen permeability> The oxygen permeability of the laminate prepared using the gas barrier films of the examples and comparative examples was measured. The measurement was carried out using an oxygen permeability measuring device (manufactured by Modern Control, product name: OXTRAN 2 / 20) under the conditions of a temperature of 30 °C and a relative humidity of 70%. The measurement method conformed to JIS K7126, Method B (isobaric method), and ASTM D3985-81, and the measured value was in the unit of [cm 3 (STP) / m 2 / day / atm]. If the oxygen permeability was 1.0 cm 3 (STP) / m 2 / day / atm or less, it was judged to have good oxygen barrier properties. The results are shown in Tables 1 and 2.

[0117]

Table 1

[0118]

Table 2

Explanation of Symbols

[0119] 1…Base material 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…Laminate, 22…Second base material film, 23…Sealant layer, 24…Adhesive layer.

Claims

1. A base film containing a polyolefin, When measuring the number of particles present on the surface of the measurement area of 0.25 mm² of the base film by X-ray CT analysis, one surface, the first surface, contains 1 to 80 particles with a particle diameter of 0.3 µm or more and less than 5 µm, and does not contain particles with a particle diameter of 5 µm or more. The second surface, which is the surface opposite to the first surface, contains 5 or more particles with a particle diameter of 3 µm or more. A base film. ２ ​

2. The base film according to claim 1, having a multilayer structure including at least two layers: a first skin layer having the first surface and a core layer.

3. The base film according to claim 2, further having a multilayer structure including a second skin layer having the second surface.

4. The base film according to claim 3, wherein the softening temperature of the second skin layer measured by local thermal analysis is 120°C or higher.

5. The base film according to claim 2, wherein the first skin layer contains a copolymer of propylene and an α-olefin.

6. A gas barrier film including the base film according to any one of claims 1 to 5 and a vapor deposition layer containing an inorganic oxide disposed on the first surface of the base film.

7. The gas barrier film according to claim 6, wherein the inorganic oxide is aluminum oxide, silicon oxide, or a mixture thereof.

8. The gas barrier film according to claim 6, further including a gas barrier coating layer disposed on the surface of the vapor deposition layer opposite to the base film.

9. The gas barrier film according to claim 6, further including an anchor coat layer disposed between the base film and the vapor deposition layer.

10. A laminate including the gas barrier film according to claim 6 and a sealant layer, wherein the sealant layer contains polypropylene.

11. The laminate according to claim 10, further including a second base film on the surface of the gas barrier film opposite to the sealant layer, wherein the second base film contains polypropylene.

12. A packaging bag formed by making a bag of the laminate according to claim 10.

Images