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

Abstract

A method for producing a gas barrier film, the method comprising: a step for forming an inorganic oxide layer on a base material layer; a step for forming a coating film by applying an active energy ray-curable resin composition on the inorganic oxide layer; and a step for forming an overcoat layer by irradiating the coating film with an active energy ray to cure the same, wherein the active energy ray-curable resin composition contains an acrylic compound having a molecular weight of 300 or more.

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 production 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 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, wherein the active energy ray-curable resin composition contains an acrylic compound having a molecular weight of 300 or more. [2] A gas barrier film comprising a substrate layer, an inorganic oxide layer, and an overcoat layer in this order, 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 a molecular weight of 300 or more. [3] The gas barrier film according to [2], wherein the active energy ray-curable resin composition contains the acrylic compound having an isocyanurate skeleton. [4] The gas barrier film according to [3], wherein the active energy ray-curable resin composition contains two or more types of the acrylic compound having an isocyanurate skeleton. [5] The gas barrier film according to [3] or [4], wherein the content of the hydroxyl group-containing acrylic compound having an isocyanurate skeleton is 30% by mass or more based on the total amount of the acrylic compounds having an isocyanurate skeleton. [6] The gas barrier film according to any one of [2] to [5], wherein the active energy ray-curable resin composition further contains an acrylic compound having a molecular weight of less than 300. [7] The gas barrier film according to any one of [2] to [6], wherein the active energy ray-curable resin composition further contains a carboxy group-containing acrylic compound having a molecular weight of less than 300. [8] The gas barrier film according to [6], wherein the content of the acrylic compound having a molecular weight of less than 300 is 10 to 2,000 parts by mass per 100 parts by mass of the acrylic compound having a molecular weight of 300 or more. [9] The gas barrier film according to [7], wherein the molecular weight of the carboxy group-containing acrylic compound is 100 or more but less than 300.

[10] The gas barrier film according to [7] or [9], wherein the content of the carboxyl group-containing acrylic compound is 10 to 600 parts by mass per 100 parts by mass of the acrylic compound having a molecular weight of 300 or more.

[11] The gas barrier film according to any one of [2] to

[10] , wherein the base layer comprises a polyolefin resin.

[12] The gas barrier film according to any one of [2] to

[11] , wherein the overcoat layer has a thickness of 0.15 to 2 μm.

[13] A packaging film comprising the gas barrier film according to any one of [2] to

[12] and a heat-sealing layer provided on the overcoat layer of the gas barrier film.

[14] A packaging material produced by forming a bag from the packaging film according to

[13] .

[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, and Fig. 2 is a schematic cross-sectional view of a gas barrier film according to a second embodiment of the present disclosure.

[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 a substrate layer, an inorganic oxide layer, and an overcoat layer in this order, the overcoat layer being a cured product of an active energy ray-curable resin composition having a crosslinked structure, and the active energy ray-curable resin composition containing an acrylic compound having a molecular weight of 300 or more.

[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 olefin-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 the organic polymer 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 substrate layer 10 and the inorganic oxide layer 40 or the overcoat layer 20, 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 include 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, and 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 substrate layer 10 and the inorganic oxide layer 40 or the overcoat layer 20. 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 polymers and derivatives thereof. The above-mentioned isocyanate compounds may be used alone or in combination of two or more.

[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 hydrolysate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and their hydrolysates, 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 0.01 μm or more, sufficient adhesion strength between the substrate layer 10 and the inorganic oxide layer 40 or the overcoat layer 20 is obtained, and the gas barrier properties are also good. If the thickness of the underlayer 30 is 1 μm or less, it becomes easier to form a uniform coated surface, and drying load and manufacturing 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 set to 1 to 200 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, the manufacturing cost can be kept low, cracks due to external forces such as bending or pulling are unlikely to occur, and deterioration of the 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 are superior in EB curing speed and UV curing speed compared to methacrylic compounds. 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 a molecular weight of 300 or more. Generally, coatings formed from acrylic compounds tend to have poor gas barrier properties, particularly oxygen barrier properties. However, by using an acrylic compound having a molecular weight of 300 or more, superior gas barrier properties can be exhibited compared to when an acrylic compound having a molecular weight of less than 300 is used. From this perspective, the molecular weight is preferably 350 or more. On the other hand, from the viewpoint of coatability as a resin composition, the upper limit of the molecular weight can be set to 1900 or less. From the viewpoint of coatability, the molecular weight may be 1000 or less, 700 or less, or 500 or less. From the viewpoint of achieving both gas barrier properties and coatability, the molecular weight is preferably 300 or more and 1900 or less, 300 or more and 1000 or less, 350 or more and 1000 or less, 350 or more and 700 or less, or 350 or more and 500 or less.

[0046] Examples of acrylic compounds having a molecular weight of 300 or more include stearyl acrylate, methoxy PEG #400 acrylate, methoxy PEG #600 acrylate, methoxy PEG #1000 acrylate, methoxy-polyethylene glycol acrylate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate, PEG #200 diacrylate, PEG #400 diacrylate, PEG #600 diacrylate, PEG #1000 diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, neopentyl glycol hydroxypivalic acid ester diacrylate, bisphenol A ethylene glycol diether diacrylate, Acrylate, bisphenol A polyethylene glycol diether diacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl bisacrylate), bisphenol A diglycidyl ether acrylic acid adduct, glycerin 1,3-diglycerolate diacrylate, tris(2-hydroxyethyl)isocyanuric acid diacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, EO-modified pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, EO-modified dipentaerythritol hexaacrylate, and the like can be used.

[0047] In addition to the above, epoxy acrylate, urethane acrylate, polyester acrylate, etc., each having a molecular weight of 300 or more, can also be used.

[0048] From the viewpoint of gas barrier properties, an acrylic compound having an isocyanurate skeleton can be used. For example, acrylic compounds having an isocyanurate skeleton such as tris(2-hydroxyethyl)isocyanuric acid diacrylate and tris(2-hydroxyethyl)isocyanuric acid triacrylate are preferably used.

[0049] The active energy ray-curable resin composition may contain two or more types of acrylic compounds having an isocyanurate skeleton from the viewpoint of adjusting the coatability of the composition.

[0050] 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.

[0051] 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.

[0052] Examples of hydroxyl group-containing acrylic compounds that can be used include 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl)bisacrylate, bisphenol A diglycidyl ether acrylic acid adduct, glycerin 1,3-diglycerolate diacrylate, tris(2-hydroxyethyl)isocyanuric acid diacrylate, and dipentaerythritol pentaacrylate.

[0053] The number of acryloyl groups contained in one molecule of an acrylic compound is N Ａ , the number of hydroxyl groups is N Ｂ Let these N Ａ , N Ｂ When the value of the following formula (1) is calculated by the above formula, the value of formula (1) is preferably 4 or more. Ａ ×2+N Ｂ × 3 ≧ 4 ... (1)

[0054] When the value of formula (1) is 4 or more, the crosslinking density due to the acryloyl group is improved compared to when the value is less than 4, making it easier to form a coating with a dense structure. This makes the coating less permeable to oxygen molecules, making it easier to exhibit better gas barrier properties. From this perspective, the value of formula (1) is preferably 5 or more, 6 or more, or 7 or more. On the other hand, the upper limit of the value of formula (1) can be, for example, 65, but from the perspective of suppressing embrittlement of the coating due to an internal structure becoming too dense and easily maintaining ease of handling (flexibility) as a film, the upper limit of the value of formula (1) may be 30 or less, or may be 15 or less.

[0055] The number of acryloyl groups contained in one molecule of the acrylic compound is N Ａ can take values ​​from 1 to 15. Ａ When N is 1 or more, a curing reaction can be caused. Ａ When the value of N is 15 or less, the flexibility of the coating film is easily maintained. This makes it difficult for the coating film to crack or peel off from the substrate layer, and makes it easy to ensure gas barrier properties. Ａ may be 2 to 10, may be 2 to 6, or may be 3 to 6.

[0056] The number of hydroxyl groups contained in one molecule of the acrylic compound is N Ｂ can take a value of 0 to 20. The acrylic compound does not need to contain a hydroxyl group, but as described above, containing a hydroxyl group tends to improve the gas barrier properties. Ｂ When the viscosity of the acrylic compound is 20 or less, it is easy to maintain a suitable viscosity of the acrylic compound. This improves the coatability and makes it easy to form a uniform coating film. Ｂ may be 0 to 15, and may be 1 to 8.

[0057] Examples of acrylic compounds having a value of 4 or greater in formula (1) include tricyclodecane dimethanol diacrylate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl)bisacrylate, bisphenol A diglycidyl ether acrylic acid adduct, glycerin 1,3-diglycerolate diacrylate, tris(2-hydroxyethyl)isocyanuric acid diacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, EO-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, EO-modified pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and EO-modified dipentaerythritol hexaacrylate.

[0058] From the viewpoint of coatability of the composition, the active energy ray-curable resin composition may further contain an acrylic compound having a molecular weight of less than 300. That is, the active energy ray-curable resin composition may contain an acrylic compound having a molecular weight of 300 or more and an acrylic compound having a molecular weight of less than 300.

[0059] Examples of acrylic compounds having a molecular weight of less than 300 include phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-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, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxyPEG#200 acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl hexahydrophthalate, 2-hydroxyethyl acrylate ... Acryloyloxyethyl phthalic acid, acrylic acid, 2-acryloyloxyethyl acid phosphate, dimethylaminoacrylate, diethylaminoacrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, isobornyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, glycerin diacrylate, glycerin triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, and the like can be used.

[0060] The active energy ray-curable resin composition may further contain a carboxy group-containing acrylic compound as an acrylic compound having a molecular weight of less than 300, from the viewpoint of improving the coatability of the composition as well as the adhesion between the overcoat layer, which is a cured product of the composition, and the inorganic oxide layer. Polar carboxy groups tend to interact strongly with the inorganic oxide layer, which tends to further improve the adhesion between the overcoat layer and the inorganic oxide layer. That is, the active energy ray-curable resin composition may contain an acrylic compound having a molecular weight of 300 or more and a carboxy group-containing acrylic compound having a molecular weight of less than 300, but the composition may also contain an acrylic compound having a molecular weight of 300 or more, a carboxy group-free acrylic compound having a molecular weight of less than 300, and a carboxy group-containing acrylic compound having a molecular weight of less than 300.

[0061] Examples of the carboxy group-containing acrylic compound that can be used include the above-mentioned 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, etc., as well as 2-carboxyethyl acrylate, ω-carboxycaprolactone monoacrylate, etc. Of these, from the viewpoints of compatibility with acrylic compounds having a molecular weight of 300 or more, gas barrier properties, etc., 2-acryloyloxyethyl succinic acid or 2-acryloyloxyethyl hexahydrophthalic acid is preferred, and 2-acryloyloxyethyl succinic acid is more preferred.

[0062] The carboxyl group-containing acrylic compound having a molecular weight of less than 300 may have a size sufficient to fill gaps between the crosslinked structures of the acrylic compound having a molecular weight of 300 or more. This facilitates obtaining a synergistic effect of improving the adhesion between the overcoat layer and the inorganic oxide layer and the gas barrier properties. From this viewpoint, the molecular weight of the carboxyl group-containing acrylic compound may be 250 or less or 200 or less. On the other hand, from the viewpoint of the curability of the composition, the molecular weight may be 100 or more. The molecular weight of the carboxyl group-containing acrylic compound is preferably 100 or more but less than 300, 100 or more but 250, or 100 or more but 200.

[0063] 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 used has two or more acryloyl groups.

[0064] 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.

[0065] As the methacrylic compound, any methacrylic compound having excellent EB curability and UV curability can be used.

[0066] For example, 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, methoxy-polyethylene glycol methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 2-methacryloyloxyethyl succinic acid, and 2-methacryloyloxyethyl hexahydrate. phthalic 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 methacrylic acid adduct, 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, dipentaerythritol hexamethacrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, etc. can be used.

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

[0068] Similar to acrylic compounds, compounds having a methacryloyl group containing a hydroxyl group (hydroxyl group-containing methacrylic compounds) can be used from the viewpoint of forming an organic polymer film with excellent gas barrier properties.

[0069] Examples of hydroxyl group-containing methacrylic compounds that can be used include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl-phthalic acid, glycerin dimethacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl) bismethacrylate, bisphenol A diglycidyl ether methacrylic acid adduct, glycerin 1,3-diglycerolate dimethacrylate, tris(2-hydroxyethyl)isocyanuric acid dimethacrylate, pentaerythritol trimethacrylate, and dipentaerythritol pentamethacrylate.

[0070] Based on the total amount of acrylic compounds contained in the active energy ray-curable resin composition, the content of acrylic compounds having a molecular weight of 300 or more can be 5% by mass or more, and may be 10% by mass or more, 30% by mass or more, or 50% by mass or more. When the content is 5% by mass or more, the gas barrier property is more likely to be improved compared to when the content is less than 5% by mass. On the other hand, the upper limit of the content is not particularly limited, but can be 100% by mass.

[0071] When the active energy ray-curable resin composition contains an acrylic compound having a molecular weight of less than 300, the content thereof can be 10 to 2,000 parts by mass or 50 to 1,000 parts by mass relative to 100 parts by mass of the acrylic compound having a molecular weight of 300 or more. However, if the content is 10 parts by mass or more, the coatability of the composition (coating liquid) is likely to be improved, and if the content is 2,000 parts by mass or less, good gas barrier properties are likely to be maintained.

[0072] When the active energy ray-curable resin composition contains a carboxy group-containing acrylic compound having a molecular weight of less than 300, the content thereof can be 10 to 600 parts by mass per 100 parts by mass of the acrylic compound having a molecular weight of 300 or more. However, if the content is 10 parts by mass or more, the coatability and adhesion of the composition (coating liquid) are likely to be improved, and if the content is 600 parts by mass or less, good gas barrier properties are likely to be maintained. From the viewpoint of achieving a good balance of coatability, adhesion, and gas barrier properties, the content of the carboxy group-containing acrylic compound having a molecular weight of less than 300 is preferably 10 to 600 parts by mass, 10 to 300 parts by mass, 20 to 300 parts by mass, 20 to 200 parts by mass, or 20 to 100 parts by mass per 100 parts by mass of the acrylic compound having a molecular weight of 300 or more.

[0073] When the active energy ray-curable resin composition contains two or more acrylic compounds having an isocyanurate skeleton, the content of the hydroxyl group-containing acrylic compounds having an isocyanurate skeleton can be 30% by mass or more, 50% by mass or more, or 70% by mass or more, based on the total amount of the acrylic compounds having an isocyanurate skeleton. When the content is 30% by mass or more, the gas barrier property is more likely to be improved compared to when the content is less than 30% by mass. On the other hand, the upper limit of the content is not particularly limited, but can be 100% by mass.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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, 0.1 to 2 μm, 0.15 to 2 μm, 0.2 to 2 μm, 0.2 to 1.5 μm, 0.2 to 1 μm, or 0.3 to 1 μm. If the thickness of the overcoat layer 20 is 0.05 μm or more, more preferably 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more, sufficient gas barrier properties are likely to be obtained. On the other hand, from the viewpoint of improving curability (if the thickness is too large, curing takes a long time) and from the viewpoint of improving adhesion between the overcoat layer and the inorganic oxide layer, the thickness can be 10 μm or less, more preferably 5 μm or less, 1.5 μm or less, or 1 μm or less.

[0078] <Method for producing gas barrier film> A method for producing 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, wherein the active energy ray-curable resin composition contains an acrylic compound having a molecular weight of 300 or more.

[0079] 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.

[0080] Next, the underlayer 30 and the inorganic oxide layer 40 or only the inorganic oxide layer 40 is formed on the substrate layer 10 .

[0081] 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, and the coating film 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.

[0082] 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.

[0083] 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, depending on the thickness of the overcoat layer 20, can be 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.

[0084] 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.

[0085] The gas barrier film may further be provided with a printing layer, a protective layer, a light-shielding layer, an adhesive layer, a heat-sealable heat-fusible layer, or other functional layers, as required.

[0086] <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.

[0087] An example of the heat-sealing layer is CPP (non-oriented polypropylene). The heat-sealing layer can be laminated on the base 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] [Formation of inorganic oxide layer] A mixed material containing two or more of metallic 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.

[0092] [Formation of Overcoat Layer] A coating liquid (active energy ray-curable resin composition) prepared according to the following procedure was applied to the inorganic oxide layer 40 using a flexographic printer to form a coating film. The coating film was then cured by EB irradiation using an electron beam irradiation device manufactured by I-Electron Beam Co., Ltd., at an acceleration voltage of 120 kV, an exposure dose of 15 kGy, and in a nitrogen atmosphere with an oxygen concentration of 100 ppm or less. The resulting overcoat layer had a thickness of 1 μm. This resulted in a gas barrier film comprising the substrate layer 10, inorganic oxide layer 40, and overcoat layer 20 in this order. (Procedure for Preparing Coating Liquid) The acrylic compounds used are listed in Table 1. In Example 1, tricyclodecane dimethanol diacrylate (product name: Light Acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) was used as the acrylic compound.

[0093] (Examples 2 to 6 and Comparative Examples 1 to 3) Gas barrier films were obtained in the same manner as in Example 1, except that the acrylic compounds shown in Table 1 were used. Table 1 also shows the molecular weight of each compound, the value of the above formula (1), and whether or not it has an isocyanurate skeleton.

[0094] Comparative Example 4 A gas barrier film was obtained in the same manner as in Example 1, except that no overcoat layer was formed.

[0095] Details of the acrylic compounds used are as follows: 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl)bisacrylate (product name: KAYARAD R-167, manufactured by Nippon Kayaku Co., Ltd.) 2-acryloyloxyethyl-2-hydroxyethyl-phthalate (product name: Light Acrylate HOA-MPE(N), manufactured by Kyoeisha Chemical Co., Ltd.) Bisphenol A diglycidyl ether acrylic acid adduct (product name: Epoxy Ester 3000A, manufactured by Kyoeisha Chemical Co., Ltd.) Tris(2-hydroxyethyl)isocyanuric acid triacrylate (product name: A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) Tris(2-hydroxyethyl)isocyanuric acid diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) Butyl acrylate (product name: Butyl Acrylate, manufactured by Tokyo Chemical Industry Co., Ltd.) Dipropylene glycol diacrylate (product name: Dipropylene Glycol Diacrylate, manufactured by Tokyo Chemical Industry Co., Ltd.) Neopentyl glycol diacrylate (product name: A-NPG, manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0096]

[0097] The gas barrier films obtained in each example were evaluated as follows, and the results are shown in Table 2.

[0098] (Curability) The curability of the overcoat layer of the gas barrier film was confirmed by the tackiness felt when the overcoat layer was rubbed with a latex glove. If the overcoat layer did not leave any scratches or become sticky, it was evaluated as ◯, and if it was sticky, it was evaluated as ×.

[0099] (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 For examples in which the curability was evaluated as x, the oxygen barrier property was not evaluated because the surface of the overcoat layer was sticky and difficult to handle.

[0100] As shown in Table 2, it is believed that by using an acrylic compound with a molecular weight of 300 or more, a strong coating film is formed by active energy ray curing, thereby exhibiting excellent oxygen barrier properties.

[0101]

[0102] Examples 2 to 4, in which the value of formula (1) was 5 or greater, exhibited oxygen barrier properties superior to those of Example 1. This is thought to be because, when the value of formula (1) was 5 or greater, the balance between the improved crosslink density due to the acryloyl groups and the interaction within the coating due to the hydroxyl groups was improved, resulting in a denser coating structure that was less permeable to oxygen molecules.

[0103] Even better oxygen barrier properties were exhibited in Examples 5 and 6, which used an acrylic compound having an isocyanurate skeleton. This is thought to be because the acrylic compound having an isocyanurate skeleton has a relatively high glass transition temperature among acrylic compounds, which suppresses thermal motion in the internal structure of the coating, increasing density and making it more difficult for oxygen molecules to pass through.

[0104] As is clear from Comparative Examples 1 to 3, when an acrylic compound having a molecular weight of less than 300 is used, the curability is insufficient to begin with, or even if the curability is sufficient, good oxygen barrier properties cannot be obtained.

[0105] Example 7 A mixture of (A) tris(2-hydroxyethyl)isocyanuric acid triacrylate (product name: A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.), which has an isocyanurate skeleton and no hydroxyl group, and (B) tris(2-hydroxyethyl)isocyanuric acid diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.), which has an isocyanurate skeleton and also has a hydroxyl group, in a mass ratio of A:B = 75:25 was used as the acrylic compound. Except for this, a gas barrier film was obtained in the same manner as in Example 1.

[0106] Examples 8 to 10 Gas barrier films were obtained in the same manner as in Example 7, except that the mass ratio of A and B was changed as shown in Table 3.

[0107]

[0108] Even when two different compounds having an isocyanurate skeleton were mixed as acrylic compounds, excellent oxygen barrier properties were still exhibited. In particular, Examples 8 to 10, in which the amount of the hydroxyl group-containing compound (B) was 30 mass% or more, exhibited oxygen barrier properties superior to those of Example 7. This is thought to be because the presence of hydroxyl groups, which have a high affinity for oxygen molecules, in the coating having an isocyanurate skeleton in its structure further suppressed the diffusion of oxygen molecules.

[0109] Example 11 As the acrylic compound, a mixture of tris(2-hydroxyethyl)isocyanuric acid diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) (C) and glycerin diacrylate (product name: M-920, manufactured by Toagosei Co., Ltd., molecular weight 200) (D) in a mass ratio of C:D = 70:30 was used. A gas barrier film was obtained in the same manner as in Example 1, except for this. The viscosity shown in Table 4 is the viscosity of the coating liquid at a shear rate of 100 (1 / s) when the coating liquid viscosity was continuously measured at a temperature of 23°C using a rheometer (HAAKE MARS, manufactured by Thermo Scientific Co., Ltd.) with a cone plate (diameter 60 mm, cone angle 1°) at a shear rate of 1 (1 / s) to 1000 (1 / s).

[0110] Examples 12 to 14 Gas barrier films were obtained in the same manner as in Example 11, except that the mass ratio of C and D was changed as shown in Table 4.

[0111] Example 15 A mixture of tris(2-hydroxyethyl)isocyanuric acid diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) (C) and 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol (product name: 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 214) (E) in a mass ratio of C:E = 70:30 was used as the acrylic compound. Except for this, a gas barrier film was obtained in the same manner as in Example 1.

[0112] Examples 16 to 18 Gas barrier films were obtained in the same manner as in Example 15, except that the mass ratio of C and E was changed as shown in Table 4.

[0113]

[0114] By combining an acrylic compound having a molecular weight of 300 or more and excellent oxygen barrier properties with a low-viscosity acrylic compound, it is possible to improve the coatability of the coating liquid while maintaining excellent oxygen barrier properties. Adjusting the viscosity of the coating liquid without using a solvent eliminates the need for a heat drying process for the coating film, making it possible to suppress dimensional changes in the substrate film and the resulting cracking of the inorganic oxide layer.

[0115] Example 19 As the acrylic compound, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid (product name: Light Acrylate HOA-MPE(N), manufactured by Kyoeisha Chemical Industry Co., Ltd.) (F) and 2-acryloyloxyethyl succinic acid (product name: Light Acrylate HOA-MS(N), manufactured by Kyoeisha Chemical Industry Co., Ltd., molecular weight 216) (G) were mixed in a mass ratio of F:G = 50:50. Except for this, a gas barrier film was obtained in the same manner as in Example 1.

[0116] Example 20 2-Acryloyloxyethylhexahydrophthalic acid (product name: Light Acrylate HOA-HH(N), manufactured by Kyoeisha Chemical Industry Co., Ltd., molecular weight 270) (H) was used instead of G. A gas barrier film was obtained in the same manner as in Example 19, except for this.

[0117] Example 21 A gas barrier film was obtained in the same manner as in Example 19, except that 2-acryloyloxyethyl phthalate (product name: M-5400, manufactured by Toagosei Co., Ltd., molecular weight: 264) (I) was used instead of G.

[0118] Example 22 As the acrylic compound, 2-acryloyloxyethyl succinic acid (product name: Light Acrylate HOA-MS (N), manufactured by Kyoeisha Chemical Co., Ltd., molecular weight 216) (G) and tris(2-hydroxyethyl) isocyanuric acid diacrylate (product name: M-215, manufactured by Toagosei Co., Ltd.) (J) were mixed in a mass ratio of G:J = 70:30. Except for this, a gas barrier film was obtained in the same manner as in Example 1.

[0119] Example 23 A gas barrier film was obtained in the same manner as in Example 22, except that a mixture of G and J in a mass ratio of 85:15 was used.

[0120] (Adhesion) The adhesion between the overcoat layer and the inorganic oxide layer was evaluated by the "X-cut tape method" of JIS K 5400. In this method, a thin cross-shaped cut is made in the overcoat layer with a cutter, cellophane tape is applied over the cut, and the degree of overcoat layer remaining on the film is observed when the tape is peeled off. If the overcoat layer did not peel off at all, it was evaluated as ○, and if it peeled off even slightly, it was evaluated as ×.

[0121]

[0122] As shown in Table 5, the results of the adhesion test were all good for Examples 19 to 23. By using a carboxyl group-containing acrylic compound having a molecular weight of less than 300 together with an acrylic compound having a molecular weight of 300 or more and having excellent oxygen barrier properties, a synergistic effect was demonstrated in improving the adhesion between the overcoat layer and the inorganic oxide layer, and the oxygen barrier properties.

[0123] 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.

[0124] 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 a molecular weight of 300 or more.

2. A gas barrier film comprising a substrate layer, an inorganic oxide layer, and an overcoat layer in this order, the overcoat layer being a cured product of an active energy ray-curable resin composition having a crosslinked structure, the active energy ray-curable resin composition containing an acrylic compound having a molecular weight of 300 or more.

3. The gas barrier film according to claim 2, wherein the active energy ray-curable resin composition contains the acrylic compound having an isocyanurate skeleton.

4. The gas barrier film according to claim 3, wherein the active energy ray-curable resin composition contains two or more types of the acrylic compound having an isocyanurate skeleton.

5. The gas barrier film according to claim 3, wherein the content of the hydroxyl-containing acrylic compound having an isocyanurate skeleton is 30 mass% or more based on the total amount of the acrylic compound having an isocyanurate skeleton.

6. The gas barrier film according to claim 2, wherein the active energy ray-curable resin composition further contains an acrylic compound having a molecular weight of less than 300.

7. The gas barrier film according to claim 2, wherein the active energy ray-curable resin composition further contains a carboxyl group-containing acrylic compound having a molecular weight of less than 300.

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

9. The gas barrier film according to claim 2, wherein the overcoat layer has a thickness of 0.15 to 2 μm.

10. A packaging film comprising the gas barrier film according to any one of claims 2 to 9 and a heat-sealing layer provided on the overcoat layer of the gas barrier film.

11. A packaging material produced by forming a bag from the packaging film according to claim 10.

Images