Method for producing gas barrier film, gas barrier film, packaging material film, and packaging material

Abstract

Provided is a method for producing a gas barrier film, the method comprising a step for forming an inorganic oxide layer on a substrate layer, a step for applying an active-energy-ray-curable resin composition onto the inorganic oxide layer to form a coating film, and a step for irradiating the coating film with an active energy ray to cure the coating film and form an overcoat layer, the active-energy-ray-curable resin composition containing an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, and the acrylic compound having two to eight ethylene oxide structures represented by formula (1) and being such that there are one to two ethylene oxide structures per ethylene oxide chain, or having 20 or more ethylene oxide structures and being such that there are 20 or more ethylene oxide structures per ethylene oxide chain.　[Formula 1]

Description

Gas barrier film manufacturing method, gas barrier film, packaging film, and packaging material

[0001] The present disclosure relates to a method for producing a gas barrier film, a gas barrier film produced by the method, a packaging film including the gas barrier film, and a packaging material produced by making a bag from the packaging film.

[0002] Packaging materials used for foods, pharmaceuticals, electronic components, machine components, etc. are required to have gas barrier properties, i.e., the ability to prevent the intrusion of gases (water vapor, oxygen, etc.) that denature the contents, in order to prevent deterioration or spoilage of the contents and maintain their functionality and quality. For this reason, film materials with gas barrier properties (gas barrier films) are used for these packaging materials.

[0003] As a packaging film having a gas barrier film, for example, Patent Document 1 proposes a laminated material produced by mixing a polyurethane resin, nitrocellulose, a silane coupling agent, and a filler with a solvent and a diluent to prepare a polyurethane resin composition, providing a thin inorganic oxide film consisting mainly of a silicon oxide vapor-deposited film formed by plasma chemical vapor deposition on one side of a flexible plastic substrate, coating the surface of the thin inorganic oxide film provided on one side of the flexible plastic substrate with the polyurethane resin composition to form a thin coating of the polyurethane resin composition, coating the surface of the thin coating of the polyurethane resin composition with an adhesive made of a two-component curing polyurethane resin that forms a film by a curing reaction between a polyester polyol or a polyether polyol and an isocyanate, and then laminating at least a heat-sealable resin layer via the adhesive layer.

[0004] Japanese Patent Application Laid-Open No. 2000-167973

[0005] Generally, a gas barrier film is produced by providing a gas barrier layer made of a material having gas barrier properties on the surface of a resin substrate. For example, in the above-mentioned Patent Document 1, a thin coating film made of a polyurethane resin composition corresponds to the gas barrier layer. The thin coating film is formed by applying the polyurethane resin composition to a target by a wet coating method such as roll coating, followed by hot air drying to remove the solvent.

[0006] However, the heat during hot air drying may deform the base film, which may cause cracks in the gas barrier layer and deteriorate the gas barrier properties (particularly the oxygen barrier properties).In recent years, from the viewpoint of improving recyclability, there has been a trend to design packaging materials using only polyolefin-based materials, and to use polyolefin-based resin films such as OPP (oriented polypropylene) and PE (polyethylene) as the base film.However, such films are easily affected by the above-mentioned heat, and there is a greater concern about deterioration in gas barrier properties.

[0007] The present disclosure has been made in view of the above circumstances, and aims to provide a method for producing a gas barrier film that can exhibit excellent gas barrier properties regardless of the heat resistance of a base film. The present disclosure also aims to provide a gas barrier film produced by the production method, a packaging film including the gas barrier film, and a packaging material produced by making a bag from the packaging film.

[0008] In order to solve the above problems, the inventors have found that it is important to form a gas barrier layer by curing a resin composition containing a specific acrylic compound with active energy rays, and have completed the manufacturing method of the present disclosure.

[0009] [1] A method for producing a gas barrier film, comprising: a step of forming an inorganic oxide layer on a base layer; a step of applying an active energy ray-curable resin composition onto the inorganic oxide layer to form a coating film; and a step of irradiating the coating film with active energy rays to cure it, thereby forming an overcoat layer, wherein the active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, and the acrylic compound is an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1), and the number of the ethylene oxide structures per ethylene oxide chain is 1 to 2, or an acrylic compound having 20 or more ethylene oxide structures, and the number of the ethylene oxide structures per ethylene oxide chain is 20 or more. [2] A gas barrier film comprising, in this order, a base layer, an inorganic oxide layer, and an overcoat layer, wherein the overcoat layer is a cured product of an active energy ray-curable resin composition having a crosslinked structure, and the active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, the acrylic compound being an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1), and wherein the number of the ethylene oxide structures per ethylene oxide chain is 1 to 2, or an acrylic compound having 20 or more ethylene oxide structures, and wherein the number of the ethylene oxide structures per ethylene oxide chain is 20 or more. [3] The gas barrier film according to [2], wherein the base layer contains a polyolefin resin. [4] The gas barrier film according to [2] or [3], wherein the overcoat layer has a thickness of 0.05 to 10 μm. [5] A packaging film comprising the gas barrier film according to any one of [2] to [4] and a heat-sealing layer provided on the overcoat layer of the gas barrier film. [6] A packaging material produced by forming a bag from the packaging film according to [5].

[0010] The present disclosure provides a method for producing a gas barrier film that can exhibit excellent gas barrier properties regardless of the heat resistance of a base film. The present disclosure also provides a gas barrier film produced by the method, a packaging film including the gas barrier film, and a packaging material produced by forming a bag from the packaging film.

[0011] Fig. 1 is a schematic cross-sectional view of a gas barrier film according to a first embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of a gas barrier film according to a second embodiment of the present disclosure. Fig. 3 is a graph showing the relationship between the number of ethylene oxide structures in an acrylic compound molecule and oxygen permeability. Fig. 4 is a graph showing the relationship between the number of ethylene oxide structures per ethylene oxide chain of an acrylic compound and oxygen permeability.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects, either singly or in combination.

[0013] Furthermore, the embodiments described below are merely examples of configurations for embodying the technical idea of ​​the present disclosure, and the technical idea of ​​the present disclosure is not limited by the materials, shapes, structures, etc. of the components described below. Various modifications can be made to the technical idea of ​​the present disclosure within the technical scope defined by the claims.

[0014] In the drawings referred to below, the same parts are denoted by the same reference numerals. The drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, and the relationship between the dimensions of one member and the dimensions of another member, etc. may differ from the actual relationship.

[0015] In the present disclosure, oxygen barrier properties, which are one aspect of gas barrier properties, are evaluated by oxygen transmission rate (OTR), and a smaller value indicates better oxygen barrier properties.

[0016] <Gas Barrier Film> The gas barrier film comprises, in this order, a substrate layer, an inorganic oxide layer, and an overcoat layer. The overcoat layer is a cured product of an active energy ray-curable resin composition having a crosslinked structure. The active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, the acrylic compound being an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1) and having 1 to 2 ethylene oxide structures per ethylene oxide chain, or an acrylic compound having 20 or more of the ethylene oxide structures and having 20 or more ethylene oxide structures per ethylene oxide chain.

[0017] First, a first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view of a gas barrier film according to a first embodiment of the present disclosure. The gas barrier film 100 includes a substrate layer 10, an underlayer 30, an inorganic oxide layer 40, and an overcoat layer 20, in this order.

[0018] An underlayer 30 is formed on the substrate layer 10. An inorganic oxide layer 40 is formed on the underlayer 30. An overcoat layer 20 is formed on the inorganic oxide layer 40.

[0019] In the gas barrier film, the underlayer 30 may not be provided, as will be described in the second embodiment.

[0020] Next, a second embodiment will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view of a gas barrier film according to the second embodiment of the present disclosure. The gas barrier film 200 is the gas barrier film 100 without the undercoat layer 30, and includes a base layer 10, an inorganic oxide layer 40, and an overcoat layer 20 in this order.

[0021] The gas barrier films according to the first and second embodiments will be described below together.

[0022] [Base Material Layer] Examples of resins constituting the base material layer 10 include polyolefin-based resins such as polyethylene, polypropylene, polymers of olefins having 2 to 10 carbon atoms, and propylene-ethylene copolymers; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide-based resins such as aliphatic polyamides such as nylon 6 and nylon 66, and aromatic polyamides such as polymetaxylylene adipamide; vinyl-based resins such as polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer; acrylic-based resins such as homopolymers or copolymers of acrylic monomers such as polymethyl methacrylate and polyacrylonitrile; cellophane; and engineering plastics such as polycarbonate and polyimide. These resins may be used alone or in combination of two or more.

[0023] Among these resins, by using a polyolefin resin film (particularly a polypropylene film, etc.), a mono-material packaging material with excellent recyclability can be obtained.

[0024] The substrate layer 10 may be a single-layer film made of a single resin, or a single-layer or laminated film made of multiple resins. The substrate layer 10 may also be one in which the above-mentioned various resins are laminated on another substrate (metal, wood, paper, ceramics, etc.).

[0025] The film constituting the base layer 10 may be an unstretched film or a stretched film such as a uniaxially stretched or biaxially stretched film. From the viewpoint of excellent water vapor barrier properties, an oriented polypropylene (OPP) film is particularly preferred as the base layer 10. When the base layer 10 includes an OPP film, the OPP film may be one layer or two or more layers.

[0026] The OPP film may be a film formed from at least one polymer selected from homopolymers, random copolymers, and block copolymers. Homopolymers are polypropylenes composed solely of propylene monomers. Random copolymers are polypropylenes in which the main monomer, propylene, is randomly copolymerized with a small amount of a comonomer different from propylene to form a homogeneous phase. Block copolymers are polypropylenes in which the main monomer, propylene, and the comonomer are copolymerized in block form or polymerized in a rubber form to form a heterogeneous phase.

[0027] The surface of the substrate layer 10 on which the underlayer 30 or the inorganic oxide layer 40 is formed may be subjected to a surface treatment such as chemical treatment, solvent treatment, corona treatment, low-temperature plasma treatment, or ozone treatment, thereby improving the adhesion between the substrate layer and the underlayer or the inorganic oxide layer.

[0028] The film constituting the base material layer 10 may contain additives such as fillers, antiblocking agents, antistatic agents, plasticizers, lubricants, antioxidants, etc. These additives may be used alone or in combination of two or more.

[0029] There is no particular limitation on the thickness of the base material layer 10, and it can be appropriately determined based on the price and application, taking into consideration the suitability as a packaging material and the suitability for laminating other coatings. The thickness of the base material layer 10 is preferably 3 to 200 μm, more preferably 5 to 120 μm, even more preferably 6 to 100 μm, and particularly preferably 10 to 30 μm.

[0030] [Undercoat Layer] The undercoat layer 30 contains an organic polymer. The content of the organic polymer in the undercoat layer 30 may be, for example, 70% by mass or more, or 80% by mass or more. Examples of organic polymers include polyacrylic resin, polyester resin, polycarbonate resin, polyol resin, polyurethane resin, polyamide resin, polyolefin resin, polyimide resin, melamine resin, and phenolic resin. In consideration of the hot water resistance of the adhesion strength between the base material layer 10 and the inorganic oxide layer 40, it is preferable that the undercoat layer 30 contain at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers.

[0031] The underlayer 30 may contain a silane coupling agent, an organic titanate, a modified silicone oil, or the like.

[0032] More preferred organic polymers used for the underlayer 30 are organic polymers having urethane bonds formed by the reaction of polyols having two or more hydroxyl groups at the molecular end or in the molecular chain with an isocyanate compound, or organic polymers containing reaction products of polyols having two or more hydroxyl groups at the molecular end or in the molecular chain with an organic silane compound such as a silane coupling agent or its hydrolysate. Either one of these may be used, or both may be used.

[0033] Examples of the polyols include at least one selected from acrylic polyol, polyvinyl acetal, polystyrene polyol, and polyurethane polyol. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer, or may be obtained by copolymerizing an acrylic acid derivative monomer with another monomer. Examples of the acrylic acid derivative monomer include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of the monomer copolymerized with the acrylic acid derivative monomer include styrene.

[0034] The isocyanate compound reacts with the polyol to form a urethane bond, thereby enhancing the adhesion between the base layer 10 and the inorganic oxide layer 40. In other words, the isocyanate compound functions as a crosslinking agent or curing agent. Examples of the isocyanate compound include aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aromatic aliphatic xylene diisocyanate (XDI), aliphatic hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), a mixture of 1-methylcyclohexane-2,4-diisocyanate and 1-methylcyclohexane-2,6-diisocyanate (HTDI, hydrogenated TDI), and cyclohexylmethane diisocyanate (HMDI, hydrogenated MDI), as well as other monomers, polymers, and derivatives thereof. The above-mentioned isocyanate compounds may be used alone or in combination.

[0035] Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-methacryloyloxypropylmethyldimethoxysilane. The organic silane compound may be a hydrolyzate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and their hydrolyzates, or two or more of them in combination.

[0036] The underlayer 30 can be formed using a mixed solution containing the above-mentioned components in any ratio in an organic solvent. The mixed solution may contain, for example, a curing accelerator such as a tertiary amine, an imidazole derivative, a metal salt compound of a carboxylic acid, a quaternary ammonium salt, or a quaternary phosphonium salt; an antioxidant such as a phenol, sulfur, or phosphite; a leveling agent; a flow adjuster; a catalyst; a crosslinking reaction accelerator; a filler; etc.

[0037] There are no particular restrictions on the thickness of the underlayer 30, and it can be, for example, 0.005 to 5 μm. The thickness can be determined appropriately depending on the application or desired properties. The thickness of the underlayer 30 is preferably 0.01 to 1 μm, and more preferably 0.01 to 0.5 μm. If the thickness of the underlayer 30 is 0.005 μm or more, particularly 0.01 μm or more, sufficient adhesion strength between the substrate layer 10 and the inorganic oxide layer 40 is obtained, and gas barrier properties are also good. If the thickness of the underlayer 30 is 5 μm or less, particularly 1 μm or less, it becomes easier to form a uniform coated surface, and drying load and production costs can be reduced.

[0038] As shown in Figure 2, if no underlayer is provided, the heating step for the base layer can be reduced. However, since the provision of the underlayer tends to improve the smoothness of the surface of the base layer, it is possible to suppress a decrease in gas barrier properties due to a decrease in the film quality of the inorganic oxide layer that is formed.

[0039] [Inorganic Oxide Layer] Examples of inorganic oxides constituting the inorganic oxide layer 40 include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, and indium oxide. Aluminum oxide or silicon oxide is particularly preferred because it has excellent productivity and excellent oxygen barrier properties and water vapor barrier properties under high temperature and high humidity conditions. The inorganic oxide layer 40 may be formed of one type of inorganic oxide, or may be formed of two or more appropriately selected inorganic oxides.

[0040] The thickness of the inorganic oxide layer 40 can be, for example, 1 to 200 nm, 10 to 100 nm, or 10 to 50 nm. If the thickness is 1 nm or more, excellent oxygen barrier properties and water vapor barrier properties are likely to be obtained. If the thickness is 200 nm or less, manufacturing costs can be kept low, cracks due to external forces such as bending or pulling are unlikely to occur, and deterioration of gas barrier properties can be easily suppressed.

[0041] The inorganic oxide layer 40 can be formed by a known film formation method such as vacuum deposition, sputtering, ion plating, or plasma chemical vapor deposition (CVD).

[0042] [Overcoat Layer (Gas Barrier Coating / Oxygen Barrier Coating)] The overcoat layer 20 is formed by curing a coating film containing an acrylic compound (a compound having an acryloyl group), and is an organic polymer film formed by applying, for example, a solventless coating liquid containing a monomer and an oligomer of an acrylic compound, i.e., an active energy ray-curable resin composition, and curing the coating film by irradiating the coating with active energy rays such as EB (electron beam) or UV (ultraviolet light). As can be seen from its manufacturing method, the overcoat layer is a cured product of the active energy ray-curable resin composition having a crosslinked structure.

[0043] The active energy ray-curable resin composition contains at least a monomer (or oligomer) of an acrylic compound, and may further contain additives such as a methacrylic compound (a compound having a methacryloyl group), a photoradical generator, a silane coupling agent, etc. Note that by using EB, the composition can be cured even if it does not contain a photoradical generator. From the viewpoint of hygiene, the composition does not need to contain a photoradical generator.

[0044] Acrylic compounds are generally low-cost active energy ray-curable compounds that have excellent EB curing speed and UV curing speed. The active energy ray-curable resin composition may contain one or more acrylic compounds.

[0045] The active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain. Here, the acrylic compound is acrylic compound A or B shown below. Acrylic compound A: An acrylic compound having two to eight ethylene oxide structures represented by the following formula (1) in the compound (per molecule), and the number of ethylene oxide structures per ethylene oxide chain is one to two. Acrylic compound B: An acrylic compound having 20 or more ethylene oxide structures in the compound (per molecule), and the number of ethylene oxide structures per ethylene oxide chain is 20 or more. Hereinafter, these acrylic compounds may be collectively referred to as "specific acrylic compounds." Generally, coatings formed from acrylic compounds tend to have poor gas barrier properties, particularly oxygen barrier properties. However, by using the specific acrylic compound, it is possible to exhibit superior gas barrier properties compared to when the specific acrylic compound is not used.

[0046] The number of acryloyl groups possessed by the specific acrylic compound is two or more, but can be, for example, 2 to 15. Having two or more acryloyl groups allows for a good curing reaction, while having 15 or fewer acryloyl groups makes it easier to maintain the flexibility of the coating. This makes it less likely for the coating to crack or peel from the substrate layer, making it easier to ensure gas barrier properties. From this perspective, the number of acryloyl groups may be 2 to 10, 2 to 6, or 3 to 6.

[0047] Ethylene oxide chains contain oxygen molecules, which gives them a polarity compared to hydrocarbon chains, which are made up of only continuous carbon atoms. This creates interactions within the crosslinked structure, making it difficult for gas molecules to pass through. Therefore, when acrylic compounds containing ethylene oxide chains are used, the oxygen barrier properties of films tend to be higher. Furthermore, changing the number of ethylene oxide structures per ethylene oxide chain changes the distance between acryloyl groups in the acrylic compound. This means that the distance between crosslinked points after curing changes, which also changes the density of the crosslinked structure.

[0048] When acrylic compound A is used, that is, when the specific acrylic compound has two or more and eight or less ethylene oxide structures, excellent gas barrier properties can be exhibited. The inventors speculate that the reason for this is as follows: When the number of ethylene oxide structures is two or more and eight or less, the acrylic compound has an increased degree of freedom of movement during the curing reaction due to irradiation with active energy rays, which is thought to increase the reactivity between acryloyl groups and enable the formation of a denser crosslinked structure. As a result, a coating with a dense internal structure that is difficult for gas molecules to permeate is formed, which is thought to improve gas barrier properties.

[0049] On the other hand, when the number of ethylene oxide structures is 9 or more and 19 or less, the curing reactivity increases as described above, but the size of each molecule increases, which is thought to increase the distance between crosslinks formed by the curing reaction of the acryloyl groups and increase the gaps within the crosslinked structure, making it easier for gas molecules to permeate and reducing the gas barrier properties.

[0050] From these viewpoints, the number of ethylene oxide structures in the acrylic compound A may be 2 or more and 6 or less, or may be 3 or more and 5 or less.

[0051] In the acrylic compound A, the number of ethylene oxide structures per ethylene oxide chain (per linear chain) is 1 or more and 2 or less. Here, the number (average number) of ethylene oxide structures per ethylene oxide chain can be determined by dividing the "number of ethylene oxide structures" in the compound by the "number of ethylene oxide chains." When the number of ethylene oxide structures per ethylene oxide chain is 2 or less, the repulsion between acrylic compounds is smaller than when more than two (e.g., 3 or more) ethylene oxide structures are connected in a linear chain, and a denser crosslinked structure can be formed.

[0052] The molecular weight of the acrylic compound A is preferably 600 or less. The fewer structures other than the ethylene oxide structure there are, the easier it is to obtain a dense crosslinked structure more efficiently. From this viewpoint, the molecular weight of the acrylic compound A is 600 or less, more preferably 520 or less. The lower limit of the molecular weight of the acrylic compound A can be, for example, 200.

[0053] Furthermore, when acrylic compound B is used, i.e., when the specific acrylic compound has 20 or more ethylene oxide structures, even better gas barrier properties can be achieved. The inventors speculate that the reason for this is as follows: When the number of ethylene oxide structures is 20 or more, as described above, the size of each molecule increases, but the repeating structural portion of the ethylene oxide structure that forms the ethylene oxide chain also increases. Therefore, it is believed that a highly crystalline aggregate structure is formed by the interaction between the ethylene oxide structures, and this aggregate structure joins with the crosslinked structure formed by the curing reaction of the acryloyl groups, forming a denser internal structure. Furthermore, although the degree of freedom of movement of the acrylic compounds is low, it is believed that the acrylic compounds are applied in a state where they are aligned with each other. This makes it extremely difficult for gas molecules to permeate, further improving gas barrier properties.

[0054] On the other hand, from the viewpoint of the strength and durability of the coating film to be formed, the upper limit of the number of ethylene oxide structures in the acrylic compound B can be set to, for example, 150, 100, or 50. In particular, from the viewpoint of easy availability of the compound, the upper limit can be set to, for example, 30.

[0055] From these viewpoints, the number of ethylene oxide structures in the acrylic compound B may be 20 or more and 150 or less, 20 or more and 100 or less, 20 or more and 50 or less, 20 or more and 30 or less, 20 or more and 25 or less, or 21 or more and 24 or less.

[0056] In acrylic compound B, the number of ethylene oxide structures per ethylene oxide chain (per linear chain) is 20 or more. When the number of ethylene oxide structures per ethylene oxide chain is 20 or more, the acrylic compound is more likely to align in the coating, and a denser crosslinked structure can be formed, compared to when fewer than 20 ethylene oxide structures (e.g., 19 or less) are connected in a linear chain. From the viewpoints of the strength and durability of the formed coating and the ease of availability of the compound, the upper limit of the number of ethylene oxide structures per ethylene oxide chain can be, for example, 30 or 25. In acrylic compound B, the number of ethylene oxide chains may be 1 to 6 or 1 to 3, and is preferably 1.

[0057] From the viewpoint of achieving both oxygen barrier properties and the strength and durability of the coating, the molecular weight of the acrylic compound B is preferably 1000 or more, more preferably 1100 or more. The upper limit of the molecular weight of the acrylic compound B can be, for example, 6000, 4000, 3000, 2500, 2000, 1500, or 1200.

[0058] The highly crystalline structure resulting from the aggregation of ethylene oxide structures can be confirmed by various analyses, such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, and X-ray diffraction (XRD).

[0059] The number of ethylene oxide structures in a specific acrylic compound can be analyzed using MALDI-TOF-MS. The number of ethylene oxide structures in a specific acrylic compound is determined by the number of ethylene oxide structures corresponding to the molecular weight with the strongest peak in the MALDI-TOF-MS mass spectrum.

[0060] When determining the number of ethylene oxide structures in a specific acrylic compound by MALDI-TOF-MS analysis, a general measurement method can be used. In this measurement method, for example, the specific acrylic compound can be mixed with a matrix and an ionizing agent and used as a measurement sample. Dithranol can be used as the matrix, and sodium iodide can be used as the ionizing agent. Then, by measuring the measurement sample in reflectron / positive mode, it is possible to detect the peak of the specific acrylic compound as a sodium ion adduct.

[0061] Examples of the acrylic compound A that can be used include diethylene glycol diacrylate (number of ethylene oxide structures: two (hereinafter, n=2), number of ethylene oxide structures per ethylene oxide chain: two (hereinafter, n / EO=2), molecular weight: 214), ethoxylated bisphenol A diacrylate (n=2, n / EO=1, molecular weight: 424), ethoxylated bisphenol A diacrylate (n=3, n / EO=1.5, molecular weight: 469), ethoxylated bisphenol A diacrylate (n=4, n / EO=2, molecular weight: 513), EO-modified trimethylolpropane triacrylate (n=3, n / EO=1, molecular weight: 428), EO-modified pentaerythritol tetraacrylate (n=4, n / EO=1, molecular weight: 529), and EO-modified dipentaerythritol hexaacrylate (n=6, n / EO=1, molecular weight: 843).

[0062] Examples of the acrylic compound B include PEG#1000 diacrylate (n=23, n / EO=23, molecular weight 1139), polyethylene glycol diacrylate, EO-modified bisphenol A diacrylate (n=40, n / EO=20, molecular weight 2099), EO-modified glycerin triacrylate (n=60, n / EO=20, molecular weight 2897), EO-modified trimethylolpropane triacrylate (n=60, n / EO=20, molecular weight 2939), EO-modified pentaerythritol tetraacrylate (n=80, n / EO=20, molecular weight 3877), and EO-modified dipentaerythritol hexaacrylate (n=120, n / EO=20, molecular weight 5865). Among these, PEG#1000 diacrylate is particularly preferred.

[0063] The active energy ray-curable resin composition may contain an acrylic compound other than the specific acrylic compound from the viewpoint of the coatability of the composition and the like.

[0064] Examples of acrylic compounds having one acryloyl group other than the specific acrylic compounds include phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, butoxyethyl acrylate, butoxydiethylene glycol acrylate, butyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxyPEG#200 acrylate, methoxy PEG#400 acrylate, methoxy PEG#600 acrylate, methoxy PEG#1000 acrylate, methoxy-polyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl hexahydrophthalate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, acrylic acid, 2-acryloyloxyethyl acid phosphate, dimethylamino acrylate, diethylamino acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, isobornyl acrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, and the like can be used.

[0065] Examples of acrylic compounds other than the specific acrylic compounds that have two acryloyl groups include PEG #400 diacrylate, PEG #600 diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, tricyclodecane dimethanol diacrylate, neopentyl glycol hydroxypivalic acid ester diacrylate, glycerin diacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl)bisacrylate, bisphenol A diglycidyl ether acrylic acid adduct, glycerin 1,3-diglycerolate diacrylate, and tris(2-hydroxyethyl)isocyanuric acid diacrylate.

[0066] Examples of acrylic compounds that can be used, other than the specific acrylic compounds, and that have three or more acryloyl groups include tris(2-hydroxyethyl)isocyanuric acid triacrylate, glycerin triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0067] In addition to the above, epoxy acrylate, urethane acrylate, polyester acrylate, etc. can also be used.

[0068] The gas barrier properties of organic polymers depend on free volume and cohesive energy. Free volume is the gap between polymers, and the smaller this is, the higher the gas barrier properties. To suppress the thermal motion of molecules, it is preferable to use a resin with a high glass transition temperature and increase its crosslink density. Many acrylic resins have a relatively low glass transition temperature.

[0069] Cohesive energy is the energy related to the strength of interaction between functional groups and polar groups and permeating gases. Chloro groups, fluoro groups, and hydroxyl groups are known to be effective against oxygen gas, with hydroxyl groups being particularly effective. Therefore, to form an organic polymer film with excellent gas barrier properties, an acrylic compound with hydroxyl groups (hydroxyl-containing acrylic compound) can be used.

[0070] From the viewpoint of forming a crosslinked structure inside the coating by EB curing and UV curing, it is preferable that at least one of the acrylic compounds other than the above-mentioned specific acrylic compounds has two or more acryloyl groups.

[0071] The active energy ray-curable resin composition may further contain a methacrylic compound (a compound having a methacryloyl group) from the viewpoints of controlling reactivity, heat resistance, etc. Methacrylic compounds are also excellent active energy ray-curable resins that can form organic polymer films at low cost.

[0072] As the methacrylic compound, any methacrylic compound having excellent EB curability and UV curability can be used.

[0073] Examples of methacrylic compounds include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, ethoxydiethylene glycol methacrylate, methoxyethylene glycol methacrylate, methoxydiethylene glycol methacrylate, methoxytriethylene glycol methacrylate, methoxydipropylene glycol methacrylate, butoxyethyl methacrylate, butoxydiethylene glycol methacrylate, butyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, methoxyPEG#200 methacrylate, methoxyPEG#400 methacrylate, methoxyPEG#600 methacrylate, methoxyPEG#1000 methacrylate, methoxypolyethylene glycol methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 2-methacryloyloxyethyl succinate, 2-methacryloyloxyethyl hexyl methacrylate, Hydrophthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl-phthalic acid, methacrylic acid, 2-methacryloyloxyethyl acid phosphate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, isobornyl methacrylate acrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, PEG#200 dimethacrylate, PEG#400 dimethacrylate, PEG#600 dimethacrylate, PEG#1000 dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-Nonanediol dimethacrylate, ditetramethylene glycol dimethacrylate, tritetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, tricyclodecane dimethanol dimethacrylate, neopentyl glycol hydroxypivalic acid ester dimethacrylate, bisphenol A ethylene glycol diether dimethacrylate, bisphenol A polyethylene glycol diether dimethacrylate, glycerin dimethacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl) bismethacrylate, bisphenol A diglycidyl ether Examples of usable copolymers include termethacrylic acid adducts, glycerin 1,3-diglycerolate dimethacrylate, tris(2-hydroxyethyl)isocyanuric acid dimethacrylate, tris(2-hydroxyethyl)isocyanuric acid trimethacrylate, trimethylolpropane trimethacrylate, EO-modified trimethylolpropane trimethacrylate, glycerin trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, EO-modified pentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, and dipentaerythritol hexamethacrylate.

[0074] In addition to the above, epoxy methacrylate, urethane methacrylate, polyester methacrylate, etc. can also be used.

[0075] Based on the total amount of acrylic compounds contained in the active energy ray-curable resin composition, the content of the specific acrylic compound can be 10% by mass or more, and may be 30% by mass or more, or 50% by mass or more. When the content is 10% by mass or more, the gas barrier property is more likely to be improved compared to when the content is less than 10% by mass. On the other hand, the upper limit of the content is not particularly limited, but from the viewpoint of gas barrier property, it can be 100% by mass (substantially not containing acrylic compounds other than the specific acrylic compound), 90% by mass, 80% by mass, 70% by mass, or 66% by mass.

[0076] When the active energy ray-curable resin composition contains an acrylic compound other than the specific acrylic compound, the content thereof can be 0 to 2000 parts by mass relative to 100 parts by mass of the specific acrylic compound. However, if the content is 50 parts by mass or more, the coatability of the composition (coating liquid) is likely to be improved. Furthermore, if the content is 900 parts by mass or less, good gas barrier properties are likely to be maintained.

[0077] From the viewpoint of gas barrier properties, the active energy ray-curable resin composition may contain 50% by mass or more of an acrylic compound, 70% by mass or more, or 80% by mass or more. On the other hand, the upper limit of the content is not particularly limited, but may be 100% by mass.

[0078] The active energy ray-curable resin composition may contain a photoradical generator as needed. Any photoradical generator capable of generating radicals upon irradiation with EB or UV can be used. The photoradical generator is not particularly limited, but examples thereof include benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, camphorquinone, 9-fluorenone, and diphenyl disulfide.

[0079] The active energy ray-curable resin composition may contain a silane coupling agent as needed. From the viewpoint of EB curability and UV curability, a silane coupling agent having an acryloyl group or a methacryloyl group is preferred. Examples of such silane coupling agents include 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and 3-acryloyloxypropyltrimethoxysilane.

[0080] The thickness of the overcoat layer 20 is set according to the required gas barrier properties, and can be, for example, 0.05 to 10 μm, 0.1 to 5 μm, 0.2 to 2 μm, or 0.3 to 1 μm. If the thickness of the overcoat layer 20 is 0.05 μm or more, and more preferably 0.1 μm or more, sufficient gas barrier properties are likely to be obtained. On the other hand, if the thickness is too thick, it takes a long time to harden, so the thickness can be set to 10 μm or less, and more preferably 5 μm or less.

[0081] <Method for manufacturing gas barrier film> A method for manufacturing a gas barrier film includes the steps of: forming an inorganic oxide layer on a substrate layer; applying an active energy ray-curable resin composition on the inorganic oxide layer to form a coating film; and irradiating the coating film with active energy rays to cure it, thereby forming an overcoat layer. The active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, and the acrylic compound is an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1) and having 1 to 2 ethylene oxide structures per ethylene oxide chain, or an acrylic compound having 20 or more of the ethylene oxide structures and having 20 or more ethylene oxide structures per ethylene oxide chain.

[0082] An example of a procedure for producing a gas barrier film will now be described. First, the substrate layer 10 is prepared. The substrate layer 10 may be a commercially available product or may be produced by a known method.

[0083] Next, the underlayer 30 and the inorganic oxide layer 40 or only the inorganic oxide layer 40 is formed on the substrate layer 10 .

[0084] To form the underlayer 30, for example, a coating agent for forming the underlayer may be applied to the substrate layer 10 by a wet coating method to form a coating film, which may then be dried (to remove the solvent) and cured. Known wet coating methods can be used to apply the coating agent. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. Known drying methods such as hot air drying, heat roll drying, and infrared irradiation can be used to dry the coating film. The drying temperature for the coating film can be, for example, 50 to 200°C. The drying time varies depending on the thickness of the coating film, the drying temperature, and the like, but can be, for example, 1 second to 5 minutes. The drying conditions for the coating film can be determined appropriately, taking into consideration the ease of drying of the solvent in the coating film, the thermal stability of the substrate layer 10, and the like.

[0085] The inorganic oxide layer 40 can be formed on the substrate layer 10 or the underlayer 30 by the above-mentioned vacuum deposition method, sputtering method, ion plating method, plasma chemical vapor deposition (CVD) method, or the like.

[0086] Next, the overcoat layer 20 is formed. The overcoat layer 20 can be formed, for example, by wet-coating the inorganic oxide layer 40 with a coating agent for forming the overcoat layer (the active energy ray-curable resin composition described above) to form a coating film, and then curing the coating film by EB or UV irradiation. The active energy ray irradiation conditions vary depending on the thickness of the overcoat layer 20, but can be, for example, a nitrogen atmosphere, an acceleration voltage of 10 to 300 kV, and an exposure dose of 15 to 120 kGy. An acceleration voltage within the above range facilitates the active energy ray's penetration deep into the coating film in the thickness direction and facilitates the suppression of degradation of the inorganic oxide layer, underlayer, substrate layer, etc. due to the active energy ray. Furthermore, an exposure dose within the above range facilitates the formation of a desired crosslinked structure within the overcoat layer 20 while suppressing yellowing and changes in mechanical properties. The coating agent can be applied using the same method as described in the process for forming the underlayer 30. The overcoat layer 20 may be formed by applying and curing once, or by repeatedly applying and curing the same or different coating agents multiple times.

[0087] The overcoat layer 20 formed as described above is a cured product of a coating agent (active energy ray-curable resin composition) having a crosslinked structure. Here, "having a crosslinked structure" means that the molecular chains of the reactive compound, including the acrylic compound, form a three-dimensional network structure. The presence of the crosslinked structure can be confirmed by various analyses, including Fourier transform infrared spectroscopy, solid-state NMR, X-ray photoelectron spectroscopy, dynamic viscoelasticity measurement, and gel fraction measurement.

[0088] The gas barrier film may further be provided with a printing layer, a protective layer (protective film), a light-shielding layer, an adhesive layer, a heat-sealable heat-fusible layer, or other functional layers, as required.

[0089] <Packaging Film and Packaging Material> The packaging film comprises the gas barrier film described above and a heat-sealing layer provided on the overcoat layer of the gas barrier film. A packaging material can be formed by preparing one or more sheets of this packaging film, placing the heat-sealing layers opposite each other, and heat-sealing the periphery. In other words, the packaging material is made into a bag from the packaging film.

[0090] An example of the heat-sealing layer is CPP (non-oriented polypropylene). The heat-sealing layer can be laminated on the overcoat layer by a known method such as dry lamination or extrusion lamination using a known adhesive such as a polyurethane-based, polyester-based, or polyether-based adhesive.

[0091] By using polypropylene for both the base layer and the heat-sealable layer, the polypropylene content in the packaging film and packaging material can be increased to 90% by mass or more, making the packaging film and packaging material a so-called mono-material material with excellent recyclability.

[0092] The packaging film can have, for example, the following layer configurations depending on the functional layer provided on the gas barrier film: Printed layer / gas barrier film / heat-sealing layer Protective layer / printed layer / gas barrier film / heat-sealing layer Printed layer / protective layer / gas barrier film / heat-sealing layer

[0093] The gas barrier film of the present disclosure will be further described using examples and comparative examples, but the present disclosure is not limited in any way by the specific contents of the examples and comparative examples.

[0094] Example 1 [Preparation of Base Layer] As the base layer 10, a biaxially oriented polypropylene film (VPH2011 manufactured by A.J. Plast Co.) having a thickness of 20 μm and having one surface subjected to a corona treatment was prepared.

[0095] [Formation of inorganic oxide layer] A mixed material containing two or more of metal silicon, silicon monoxide, and silicon dioxide was evaporated using a vacuum deposition apparatus using an electron beam heating system to form an inorganic oxide layer 40 (silicon oxide vapor deposition layer) made of silicon oxide and having a thickness of 30 nm on the corona-treated surface of the substrate layer 10.

[0096] [Formation of Overcoat Layer] Diethylene glycol diacrylate (product name: Diethylene glycol diacrylate, manufactured by Tokyo Chemical Industry Co., Ltd.) was applied (wet coated) onto the inorganic oxide layer 40 as a coating liquid (active energy ray-curable resin composition) using a flexographic printing machine to form a coating film. Then, using an electron beam irradiation device manufactured by I-Electron Beam Co., Ltd., the coating film was irradiated with EB at an acceleration voltage of 120 kV, an exposure dose of 60 kGy, and in a nitrogen atmosphere with an oxygen concentration of 100 ppm or less, and cured. The resulting overcoat layer had a thickness of 1 μm. This resulted in a gas barrier film having the substrate layer 10 / inorganic oxide layer 40 / overcoat layer 20 in this order.

[0097] Examples 2 to 5 and Comparative Examples 1 to 6 Gas barrier films were obtained in the same manner as in Example 1, except that the acrylic compounds shown in Table 1 were used.

[0098] Details of the acrylic compounds used are as follows: For example, "n=3" indicates that the number of ethylene oxide structures in the acrylic compound is 3. Ethoxylated bisphenol A diacrylate (n=3) (product name: Bisphenol A polyethylene glycol diether diacrylate (n=approx. 3), manufactured by Tokyo Chemical Industry Co., Ltd.) EO-modified trimethylolpropane triacrylate (n=3) (product name: NK Ester A-TMMT-3EO, manufactured by Shin-Nakamura Chemical Co., Ltd.) Ethoxylated bisphenol A diacrylate (n=4) (product name: Light Acrylate BP-4EAL, manufactured by Kyoeisha Chemical Co., Ltd.) PEG #1000 diacrylate (product name: NK Ester A-1000, manufactured by Shin-Nakamura Chemical Co., Ltd.) PEG #400 diacrylate (product name: Light Acrylate 9EG-A, manufactured by Kyoeisha Chemical Co., Ltd.) EO-modified trimethylolpropane triacrylate (n=9) (product name: NK Ester A-TMMT-9EO, manufactured by Shin-Nakamura Chemical Co., Ltd.) Ethoxylated bisphenol A diacrylate (n=10) (product name: Bisphenol A polyethylene glycol diether diacrylate (n=approx. 10), manufactured by Tokyo Chemical Industry Co., Ltd.) PEG #600 diacrylate (product name: Light Acrylate 14EG-A, manufactured by Kyoeisha Chemical Co., Ltd.) Methoxy PEG #600 acrylate (product name: NK Ester AM-130G, manufactured by Shin-Nakamura Chemical Co., Ltd.) Methoxy PEG #1000 acrylate (product name: NK Ester AM-230G, manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0099]

[0100] The gas barrier films obtained in each example were evaluated as follows, and the results are shown in Table 2.

[0101] (Curing property) The curing property of the overcoat layer of the gas barrier film was confirmed by the tackiness when the overcoat layer was rubbed with a latex glove. The rating was ◯ when no scratch marks were left on the overcoat layer and no stickiness was observed, △ when stickiness was observed but the overcoat layer did not adhere to the latex glove, and × when stickiness was observed and the overcoat layer adhered to the latex glove.

[0102] (Oxygen Barrier Property) The oxygen permeability (cc / m) of the gas barrier film obtained in each example was measured using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON Corporation) in an atmosphere of 30°C and 70% RH (relative humidity). ２ / day / atm) was measured.

[0103]

[0104] As shown in Table 2, it is believed that by using a specific acrylic compound, namely, an acrylic compound having two or more acryloyl groups and ethylene oxide chains, namely, acrylic compound A having 2 to 8 ethylene oxide structures represented by the above formula (1) and the number of ethylene oxide structures per ethylene oxide chain being 1 to 2, or acrylic compound B having 20 or more ethylene oxide structures and the number of ethylene oxide structures per ethylene oxide chain being 20 or more, a coating film with a dense structure was formed due to the increased crosslinking density caused by the acryloyl groups, and excellent oxygen barrier properties (performance that makes it difficult for oxygen molecules to pass through) were obtained.

[0105] As is clear from Comparative Examples 1 to 5, when an acrylic compound having more than 8 or less than 20 ethylene oxide structures is used, good oxygen barrier properties cannot be obtained even if the curability is sufficient.

[0106] Furthermore, as is clear from Comparative Examples 5 and 6, when an acrylic compound having one acryloyl group was used, the resulting coating surface was sticky, resulting in insufficient properties as an overcoat layer, and further reduced oxygen barrier properties. The oxygen barrier properties of these examples were comparable to those obtained when no overcoat layer was formed (i.e., when the substrate had an inorganic oxide layer formed thereon), indicating that the overcoat layer was unable to exhibit sufficient oxygen barrier properties.

[0107] The above results are summarized in Figures 3 and 4. Figure 3 is a graph showing the relationship between the number of ethylene oxide structures in the molecule of an acrylic compound and oxygen permeability. Figure 4 is a graph showing the relationship between the number of ethylene oxide structures per ethylene oxide chain of an acrylic compound and oxygen permeability.

[0108] The above describes the embodiments and examples of the present disclosure, but the specific configuration of the present disclosure is not limited to those contents, and modifications and combinations of the configuration are possible within the scope that does not deviate from the gist of the present disclosure.

[0109] 10... base layer, 20... overcoat layer, 30... underlayer, 40... inorganic oxide layer, 100, 200... gas barrier film.

Claims

1. A method for producing a gas barrier film, comprising: a step of forming an inorganic oxide layer on a substrate layer; a step of applying an active energy ray-curable resin composition onto the inorganic oxide layer to form a coating film; and a step of irradiating the coating film with active energy rays to cure it, thereby forming an overcoat layer, wherein the active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, and the acrylic compound is an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1), and the number of ethylene oxide structures per ethylene oxide chain is 1 to 2, or an acrylic compound having 20 or more ethylene oxide structures, and the number of ethylene oxide structures per ethylene oxide chain is 20 or more.

2. A gas barrier film comprising, in this order, a substrate layer, an inorganic oxide layer, and an overcoat layer, wherein the overcoat layer is a cured product of an active energy ray-curable resin composition having a crosslinked structure, and the active energy ray-curable resin composition contains an acrylic compound having two or more acryloyl groups and an ethylene oxide chain, the acrylic compound being an acrylic compound having 2 to 8 ethylene oxide structures represented by the following formula (1), and wherein the number of ethylene oxide structures per ethylene oxide chain is 1 to 2, or an acrylic compound having 20 or more ethylene oxide structures, and wherein the number of ethylene oxide structures per ethylene oxide chain is 20 or more.

3. The gas barrier film according to claim 2, wherein the substrate layer comprises a polyolefin resin.

4. The gas barrier film according to claim 2, wherein the overcoat layer has a thickness of 0.05 to 10 μm.

5. A packaging film comprising the gas barrier film according to any one of claims 2 to 4 and a heat-sealing layer provided on the overcoat layer of the gas barrier film.

6. A packaging material produced by forming a bag from the packaging film according to claim 5.

Images