Gas barrier film

Abstract

To provide a gas barrier film that exhibits excellent adhesion and gas barrier properties, regardless of the heat resistance of the substrate layer. [Solution] The gas barrier film 10 comprises a base layer 1, an inorganic oxide layer 2, and an overcoat layer 3 in this order, the overcoat layer 3 being a cured product of an active energy ray curable resin composition, and the active energy ray curable resin composition contains a carboxyl group-containing (meth)acrylic compound.

Description

Technical Field

[0001] The present invention relates to a gas barrier film.

Background Art

[0002] Packaging materials used for foods, pharmaceuticals, electronic components, mechanical components, etc. are required to have a property of preventing the intrusion of gases such as oxygen and water vapor that can modify the contents, in order to suppress the deterioration and spoilage of the contents and maintain their functions and qualities, that is, gas barrier properties. Therefore, gas barrier films are used for these packaging materials.

[0003] Generally, a gas barrier film is provided with a gas barrier layer made of a material having gas barrier properties on a resin substrate. For example, Patent Document 1 describes a gas barrier film provided with a gas barrier layer formed by applying a urethane-based coating solution having gas barrier properties on a vapor deposition film made of an inorganic oxide provided on one surface of a plastic substrate and drying this by hot air.

[0004] However, the base film may be deformed by the heat during hot air drying, which may cause cracks in the gas barrier layer and deterioration of the gas barrier properties (particularly oxygen barrier properties). In recent years, from the viewpoint of improving recyclability, polyolefin-based resin films such as OPP (oriented polypropylene) and PE (polyethylene) are tending to be adopted as the base film in order to design a so-called monomaterial packaging material using a single polyolefin-based material. Such films are easily affected by the above heat, and deterioration of gas barrier properties is more of a concern.

[0005] On the other hand, as a film-forming process that does not involve the above heating step, (meth)acrylic resin can be used and cured by electron beam (EB) or ultraviolet ray (UV) to form a gas barrier layer (see, for example, Patent Documents 2 or 3).

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-167973 [Patent Document 2] Japanese Patent Publication No. 2006-95932 [Patent Document 3] Japanese Patent Publication No. 2020-108968 [Overview of the project] [Problems that the invention aims to solve]

[0007] A (meth)acrylic resin layer formed on a vapor-deposited film made of inorganic oxides by active energy ray curing such as EB curing or UV curing has the problem of poor adhesion to the vapor-deposited film made of inorganic oxides.

[0008] In contrast, a known technique involves providing a primer layer between a vapor-deposited film made of an inorganic oxide and a (meth)acrylic resin layer, as described in Patent Document 2. However, in this technique, since each layer is laminated while still in the liquid phase before crosslinking, it is difficult to ensure consistent mixing of the two layers. Furthermore, a mechanism for evaporating two types of monomers is required, making the apparatus complex.

[0009] Furthermore, there is a known technique for improving adhesion by adding a silane coupling agent, as described in Patent Document 3. However, this technique requires the addition of a large amount of silane coupling agent. This poses hygiene problems, particularly when used as a food packaging material, due to the residue of uncured monomers. Moreover, even with this technique, sufficient adhesion cannot be obtained in the region where the film thickness exceeds 150 nm, and sufficient barrier properties cannot be obtained by keeping the film thickness low.

[0010] The present invention aims to provide a gas barrier film that exhibits excellent adhesion and gas barrier properties, regardless of the heat resistance of the substrate layer. [Means for solving the problem]

[0011] According to one aspect of the present invention, a gas barrier film is provided comprising a base 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, and the active energy ray curable resin composition contains a carboxyl group-containing (meth)acrylic compound.

[0012] According to another aspect of the present invention, a gas barrier film is provided that contains a carboxyl group-containing (meth)acrylic compound having a carboxylate equivalent of less than 300.

[0013] According to yet another aspect of the present invention, the carboxyl group-containing (meth)acrylic compound is provided as a gas barrier film relating to any of the above aspects, comprising a carboxyl group-containing (meth)acrylic compound having a cyclic structure.

[0014] According to yet another aspect of the present invention, the carboxyl group-containing (meth)acrylic compound is provided as a gas barrier film relating to any of the above aspects, comprising a carboxyl group-containing (meth)acrylic compound having an alicyclic structure.

[0015] According to yet another aspect of the present invention, the carboxyl group-containing (meth)acrylic compound is provided as a gas barrier film relating to any of the above aspects, comprising a monofunctional carboxyl group-containing (meth)acrylic compound having one (meth)acryloyl group.

[0016] According to yet another aspect of the present invention, the carboxyl group-containing (meth)acrylic compound provides a gas barrier film having a (meth)acryloyloxyethyl group according to any of the above aspects.

[0017] According to yet another aspect of the present invention, a gas barrier film is provided which contains two or more carboxyl group-containing (meth)acrylic compounds having a carboxylic acid equivalent of less than 300, as described above.

[0018] According to still another aspect of the present invention, a gas barrier film according to any one of the above aspects containing a polyolefin resin is provided on the base material layer.

[0019] According to still another aspect of the present invention, a gas barrier film according to any one of the above aspects having a thickness within the range of 0.05 μm to 10 μm is provided on the overcoat layer.

[0020] According to still another aspect of the present invention, a packaging material is provided that includes a gas barrier film according to any one of the above aspects and a heat-sealing layer provided on the overcoat layer included in the gas barrier film.

[0021] According to still another aspect of the present invention, a package including the packaging material according to the above aspect is provided.

[0022] According to still another aspect of the present invention, a packaged article is provided that includes the package according to the above aspect and an article housed in the package. [[ID=第十九]]

[0023] [[ID=第二十]] [[ID=第二十一]]According to still another aspect of the present invention, a method for manufacturing a gas barrier film is provided that includes forming an inorganic oxide layer on the base material layer, forming a coating film of an active energy ray-curable resin composition on the inorganic oxide layer, and forming an overcoat layer made of a cured product of the active energy ray-curable resin composition by irradiating the coating film with active energy rays, wherein the active energy ray-curable resin composition contains a carboxyl group-containing (meth)acrylic compound.

[0024] According to still another aspect of the present invention, a manufacturing method according to the above aspect is provided, wherein the carboxyl group-containing (meth)acrylic compound contains a carboxyl group-containing (meth)acrylic compound having a carboxylic acid equivalent of less than 300.

Advantages of the Invention

[0025] According to the present invention, a gas barrier film is provided that exhibits excellent adhesion and gas barrier properties, regardless of the heat resistance of the substrate layer. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a cross-sectional view of a gas barrier film according to one embodiment of the present invention. [Figure 2] Figure 2 is a cross-sectional view of a gas barrier film according to one modified example. [Figure 3] Figure 3 is a cross-sectional view of the packaging material containing the gas barrier film shown in Figure 1. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are more specific to any of the above aspects. The matters described below can be incorporated into each of the above aspects, individually or in combination.

[0028] Furthermore, the embodiments shown below illustrate configurations for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited by the material, shape, and structure of the components described below. Various modifications can be made to the technical concept of the present invention within the technical scope defined by the claims described in the claims.

[0029] Elements with similar or identical functions are given the same reference numerals in the drawings referenced below, and redundant explanations are omitted. Furthermore, the drawings are schematic, and the relationships between dimensions in one direction and those in another, and the relationships between the dimensions of one component and those of other components, may differ from reality.

[0030] <Gas barrier film> Figure 1 is a cross-sectional view of a gas barrier film according to one embodiment of the present invention. The gas barrier film 10 shown in Figure 1 includes a base layer 1, an inorganic oxide layer 2, and an overcoat layer 3. The overcoat layer 3 is a cured product of an active energy ray curable resin composition containing a (meth)acrylic compound. The active energy ray curable resin composition contains at least a carboxyl group-containing (meth)acrylic compound as the (meth)acrylic compound.

[0031] Here, "(meth)acrylic compound" means either or both of "acrylic compound" and / or "methacrylic compound." "Carboxyle group-containing (meth)acrylic compound" means a (meth)acrylic compound that has a carboxyle group.

[0032] The gas barrier film 10 improves upon the conventional adhesion problems between the (meth)acrylic resin layer and the inorganic oxide layer by providing an overcoat layer 3, which is made of a cured film of an active energy ray curable resin composition containing a carboxyl group-containing (meth)acrylic compound, on top of the inorganic oxide layer 2, thereby achieving a high level of both adhesion and gas barrier properties. Furthermore, in the manufacturing method of the gas barrier film 10, the film formation process of the overcoat layer 3 does not require a heating step for solvent removal or the like. For this reason, the gas barrier film 10 is suitable for use as a so-called monomaterial packaging gas barrier film, and it is easy to use a polypropylene-based film as the base layer 1.

[0033] The following describes each layer included in the gas barrier film 10. However, the gas barrier film according to this embodiment may further include one or more layers other than the base layer 1, inorganic oxide layer 2, and overcoat layer 3, if necessary.

[0034] [Base material layer] Examples of resins constituting the base layer 1 include olefin resins such as polyethylene, polypropylene, polymers of olefins having 2 to 10 carbon atoms, and propylene-ethylene copolymers; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as aliphatic polyamides such as nylon 6 and nylon 66, and aromatic polyamides such as polymetaxylylene adipamide; vinyl resins such as polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers; acrylic resins such as polymethyl methacrylate and acrylic monomers such as polyacrylonitrile, either alone or as copolymers; cellophane; and engineering plastics such as polycarbonate and polyimide. These resins may be used individually or in combination of two or more.

[0035] By using polyolefin resin films (especially polypropylene films) among these resins, it is possible to obtain monomaterial packaging materials with excellent recyclability.

[0036] The base layer 1 may be a single-layer film made of a single resin, or a single-layer or laminated film using multiple resins. The base layer 1 may also be a laminate of the above-mentioned resins on another base material (metal, wood, paper, ceramics, etc.).

[0037] The film constituting the base layer 1 may be an unstretched film, or it may be a stretched film such as a uniaxially stretched or biaxially stretched film. From the viewpoint of excellent water vapor barrier properties, stretched polypropylene (OPP) film is particularly preferred as the base layer 1. When the base layer 1 includes an OPP film, there may be one or two or more layers of OPP film.

[0038] OPP film may be made by processing at least one polymer selected from homopolymers, random copolymers, and block copolymers into a film. Homopolymer is polypropylene consisting only of propylene monomers. Random copolymer is polypropylene in which propylene, the main monomer, and a small amount of comonomers different from propylene are randomly copolymerized to form a homogeneous phase. Block copolymer is polypropylene in which propylene, the main monomer, and the above comonomers copolymerize in a block-like manner or polymerize in a rubber-like manner to form a heterogeneous phase.

[0039] The surface of the substrate layer 1 on which the inorganic oxide layer 2 is formed may be subjected to surface treatments such as chemical treatment, solvent treatment, corona treatment, low-temperature plasma treatment, or ozone treatment. Furthermore, an "easy-adhesion layer" may be provided on the surface on which the inorganic oxide layer 2 is formed. This improves the adhesion between the substrate layer 1 and the inorganic oxide layer 2.

[0040] The film constituting the base layer 1 may contain additives such as fillers, antiblocking agents, antistatic agents, plasticizers, lubricants, and antioxidants. These additives may be used individually or in combination of two or more.

[0041] The thickness of the base layer 1 can be appropriately determined depending on the application and cost, taking into consideration its suitability as a packaging material and its suitability for lamination of other coatings. In practical terms, the thickness of the base layer 1 is preferably in the range of 3 μm to 200 μm, more preferably in the range of 5 μm to 120 μm, even more preferably in the range of 6 μm to 100 μm, and particularly preferably in the range of 10 μm to 30 μm.

[0042] Furthermore, as will be described later, a base layer may be provided on the main surface of the base layer 1. By providing a base layer, the smoothness of the surface of the base layer 1 is improved, making it possible to improve the film quality of the inorganic oxide layer 2 formed thereon. On the other hand, if a base layer is not provided, for example, the heating process applied to the base layer 1 can be reduced.

[0043] [Inorganic oxide layer] Examples of inorganic oxides constituting the inorganic oxide layer 2 include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, and indium oxide. In particular, aluminum oxide or silicon oxide are preferred because they offer excellent productivity and superior oxygen barrier and water vapor barrier properties under high temperature and high humidity conditions. The inorganic oxide layer 2 may be formed from one type of inorganic oxide, or from two or more inorganic oxides selected as appropriate.

[0044] The thickness of the inorganic oxide layer 2 can be, for example, within the range of 1 nm to 200 nm. If the thickness is 1 nm or more, excellent oxygen barrier and water vapor barrier properties are easily obtained. If the thickness is 200 nm or less, manufacturing costs can be kept low, and cracks caused by external forces such as bending and pulling are less likely to occur, making it easier to suppress deterioration of gas barrier properties.

[0045] The inorganic oxide layer 2 can be formed by known film deposition methods such as vacuum deposition, sputtering, ion plating, or plasma vapor deposition (CVD).

[0046] [Overcoat layer] The overcoat layer 3 consists of a cured product of an active energy ray curable resin composition containing a (meth)acrylic compound. The overcoat layer 3 is, for example, an organic polymer film obtained by curing a coating film of a solvent-free active energy ray curable resin composition containing a (meth)acrylic compound by irradiation with active energy rays such as EB (electron beam) or UV (ultraviolet).

[0047] The active energy ray curable resin composition contains a carboxyl group-containing (meth)acrylic compound as the (meth)acrylic compound. The carboxyl group-containing (meth)acrylic compound is a compound having one or more carboxyl groups and one or more (meth)acryloyl groups in its molecule, and may be a monomer or an oligomer.

[0048] Generally, (meth)acrylic compounds are active energy ray curable compounds with excellent EB and UV curing rates. However, curing with active energy rays weakens adhesion to the substrate interface due to curing shrinkage and stress differences with the substrate. Furthermore, coatings formed from (meth)acrylic compounds tend to have poor gas barrier properties, particularly oxygen barrier properties. In contrast, by using a carboxyl group-containing (meth)acrylic compound as the material for forming the overcoat layer 3, adhesion to the inorganic oxide layer 2 is improved and excellent gas barrier properties are achieved compared to using a carboxyl group-free (meth)acrylic compound.

[0049] The reason for this improvement in adhesion and gas barrier properties is presumed to be due to intermolecular interactions originating from the carboxyl groups contained in the (meth)acrylic compound. Specifically, it is thought that intermolecular interactions originating from the carboxyl groups contained in the (meth)acrylic compound occur at the interface between the overcoat layer 3 and the inorganic oxide layer 2, resulting in improved adhesion between these two layers. Furthermore, it is thought that intermolecular interactions resulting from the association of carboxyl groups lead to the formation of pseudo-crosslinks between polymers within the overcoat layer 3, thereby improving gas barrier properties.

[0050] Furthermore, the overcoat layer 3 formed using a carboxyl group-containing (meth)acrylic compound also possesses flexibility. This is presumed to be because the intermolecular interactions originating from the carboxyl group are not particularly strong as a bonding force, thus not restricting the movement of the polymer. For this reason, the gas barrier film 10 is also useful as a packaging material where flexibility is desired.

[0051] A carboxyl group-containing (meth)acrylic compound may be a monofunctional (meth)acrylic compound having only one (meth)acryloyl group, or a polyfunctional (meth)acrylic compound having two or more (meth)acryloyl groups. When a carboxyl group-containing (meth)acrylic compound is polyfunctional, the number of (meth)acryloyl groups may be, for example, 2 to 10. In the following, a monofunctional carboxyl group-containing (meth)acrylic compound having only one (meth)acryloyl group may be referred to as a "carboxyl group-containing monofunctional (meth)acrylic compound."

[0052] Generally, increasing the number of (meth)acryloyl groups improves the degree of crosslinking and yields a dense cured film; therefore, from the viewpoint of gas barrier properties, it is preferable to use polyfunctional (meth)acrylic compounds. On the other hand, increasing the number of (meth)acryloyl groups increases the internal stress due to curing shrinkage, which tends to reduce adhesion to the substrate. In contrast, carboxyl group-containing (meth)acrylic compounds exhibit excellent gas barrier properties regardless of the number of (meth)acryloyl groups (i.e., even if monofunctional). When a carboxyl group-containing monofunctional (meth)acrylic compound is used instead of a polyfunctional (meth)acrylic compound, the problem of reduced adhesion due to increased internal stress caused by curing shrinkage, as described above, does not occur. For this reason, it is preferable that the active energy ray curable resin composition contains a carboxyl group-containing monofunctional (meth)acrylic compound.

[0053] The (meth)acryloyl group in the carboxyl group-containing (meth)acrylic compound is preferably a (meth)acryloyloxyethyl group. The active energy ray-curable resin composition preferably contains a carboxyl group-containing (meth)acrylic compound having a (meth)acryloyloxyethyl group, and more preferably contains a carboxyl group-containing monofunctional (meth)acrylic compound having only one (meth)acryloyloxyethyl group.

[0054] The carboxyl group-containing (meth)acrylic compound preferably has a carboxylic acid equivalent of less than 300. Here, the carboxylic acid equivalent is the molecular weight of the carboxyl group-containing (meth)acrylic compound per carboxyl group. Having a carboxylic acid equivalent of less than 300 is preferable from the viewpoint of improving adhesion and gas barrier properties due to the intermolecular interactions originating from the carboxyl groups mentioned above. Furthermore, a carboxyl group-containing (meth)acrylic compound with a carboxylic acid equivalent of less than 300 is preferable from the viewpoint of the applicability of the active energy ray-curable resin composition and the smoothness of the coating film, as it suppresses an increase in the viscosity of the active energy ray-curable resin composition.

[0055] The carboxylic acid equivalent of the carboxyl group-containing (meth)acrylic compound is preferably less than 300, as described above, and may be 280 or less in one example and 270 or less in other examples. Furthermore, the carboxylic acid equivalent of the carboxyl group-containing (meth)acrylic compound may be 100 or more in one example and 140 or more in other examples.

[0056] The number of carboxyl groups in a carboxyl group-containing (meth)acrylic compound is preferably such that the carboxylic acid equivalent is within the range described above. When the carboxylic acid equivalent is within the range described above, the number of carboxyl groups in the carboxyl group-containing (meth)acrylic compound may be 1 or 2 or more.

[0057] When a carboxyl group-containing (meth)acrylic compound has a cyclic structure, it exhibits particularly excellent gas barrier properties. This is presumed to be because the relatively rigid cyclic structure present in the coating suppresses the thermal motion of the polymer chains, making it difficult for oxygen molecules to permeate. For this reason, carboxyl group-containing (meth)acrylic compounds with a cyclic structure are suitably used in applications where particularly high gas barrier properties are desired.

[0058] The cyclic structure of a carboxyl group-containing (meth)acrylic compound may be an aromatic ring structure or an alicyclic structure. The aromatic ring structure may be an aromatic hydrocarbon ring or an aromatic heterocycle. The alicyclic structure may be an aliphatic hydrocarbon ring or an aliphatic heterocycle. Furthermore, the cyclic structure may be monocyclic, polycyclic, or fused ring. Examples of aromatic ring structures include benzene rings, naphthalene rings, furan rings, and pyridine rings. For alicyclic structures, alicyclic hydrocarbon groups having 3 to 12 carbon atoms are preferred, such as cyclohexane, cyclopentane, and tricyclodecane.

[0059] Examples of carboxyl group-containing (meth)acrylic compounds with a carboxylic acid equivalent of less than 300 include acrylic compounds such as 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl maleic acid, carboxyethyl acrylate, and ω-carboxycaprolactone monoacrylate, and methacrylic compounds such as 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl maleic acid, carboxyethyl methacrylate, and ω-carboxycaprolactone monomethacrylate.

[0060] Of the above specific examples, carboxyl group-containing (meth)acrylic compounds having a cyclic structure, such as 2-acryloyloxyethylhexahydrophthalic acid, 2-acryloyloxyethyl phthalic acid, 2-methacryloyloxyethylhexahydrophthalic acid, and 2-methacryloyloxyethyl phthalic acid, are preferably used, particularly from the viewpoint of gas barrier properties.

[0061] Examples of carboxyl group-containing (meth)acrylic compounds with a carboxylic acid equivalent of 300 or more include ω-carboxypolycaprolactone monoacrylate and ω-carboxypolycaprolactone monomethacrylate.

[0062] In addition to the above, other carboxyl group-containing (meth)acrylic compounds that can be used include polyester (meth)acrylate having a carboxyl group, epoxy (meth)acrylate having a carboxyl group, urethane (meth)acrylate having a carboxyl group, etc.

[0063] The active energy ray curable resin composition may contain a (meth)acrylic compound that does not contain a carboxyl group.

[0064] (Meth)acrylic compounds that do not contain a carboxyl group and have one acryloyl group include, for example, phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-triethylene glycol acrylate, methoxy-dipropylene glycol acrylate, butoxyethyl acrylate, butoxy-diethylene glycol acrylate, butyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, methoxy-ethylene glycol acrylate, methoxy-diethylene glycol acrylate, methoxy PEG #200 acrylate, methoxy PEG #400 acrylate, and Toxy PEG #600 acrylate, methoxy PEG #1000 acrylate, methoxy-polyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl acid phosphate, dimethylaminoacrylate, diethylaminoacrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, cyclohexyl acrylate, isobornyl acrylate, N-succinimidyl acrylate, N-acryloyloxyethyl hexahydrophthalimide, N-acryloyloxyethyl phthalimide, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, etc. can be used.

[0065] (Meth)acrylic compounds that do not contain a carboxyl group and have one methacryloyl group include, for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, ethoxy-diethylene glycol methacrylate, methoxy-ethylene glycol methacrylate, methoxy-diethylene glycol methacrylate, methoxy-triethylene glycol methacrylate, methoxy-dipropylene glycol methacrylate, butoxyethyl methacrylate, butoxy-diethylene glycol methacrylate, butyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, benzyl methacrylate, methoxy PEG #200 methacrylate, and methoxy PEG #400 methacrylate. Methacrylates such as methoxy-PEG#600 methacrylate, methoxy-PEG#1000 methacrylate, methoxy-polyethylene glycol methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 2-methacryloyloxyethyl-2-hydroxyethyl phthalate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-methacryloyloxyethyl acid phosphate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, isovonyl methacrylate, N-succinimidyl methacrylate, N-methacryloyloxyethyl hexahydrophthalimide, N-methacryloyloxyethyl phthalimide, and 2-(4-benzoyl-3-hydroxyphenoxy)ethyl methacrylate can be used.

[0066] (Meth)acrylic compounds that do not contain carboxyl groups and have two acryloyl groups include, for example, diethylene glycol diacrylate, triethylene glycol diacrylate, pentaethylene glycol diacrylate, hexaethylene glycol diacrylate, octaethylene glycol diacrylate, PEG#200 diacrylate, PEG#400 diacrylate, PEG#600 diacrylate, PEG#1000 diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 1,9-nonanediol diacrylate, polytetramethylene glycol diacrylate, 1,6-bis(acryloyloxy)-2,2,3,3,4,4,5,5-octafluorohexane, neopentyl glycol diacrylate You can use rilate, tricyclodecanedimethanol diacrylate, neopentyl glycol hydroxypivalate diacrylate, caprolactone-modified neopentyl glycol hydroxypivalate 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, tris(2-hydroxyethyl)isocyanurate diacrylate, ethoxylated bisphenol A diacrylate (n=2), ethoxylated bisphenol A diacrylate (n=3), ethoxylated bisphenol A diacrylate (n=4), bisphenol A polyethylene glycol diether diacrylate, bisphenol A polypropylene glycol diether diacrylate, 9,9-bis(4-(2-acryloyloxyethoxy)phenyl)fluorene, etc.

[0067] Examples of (meth)acrylic compounds that do not contain carboxyl groups and have two methacryloyl groups include 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, 3-methyl-1,5-pentanediol dimethacrylate, 1,9-nonanediol dimethacrylate, and ditetramethylene Glycol dimethacrylate, tritetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, tricyclodecane dimethanol dimethacrylate, neopentyl glycol hydroxypivalate 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 methacrylate adduct, glycerin 1,3-diglycerolate dimethacrylate, tris(2-hydroxyethyl)isocyanurate dimethacrylate, etc. can be used.

[0068] Examples of (meth)acrylic compounds that do not contain carboxyl groups and have three or more acryloyl groups include tris(2-hydroxyethyl)isocyanurate triacrylate, glycerin triacrylate, EO-modified glycerin triacrylate, PO-modified glycerin triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol You can use ditrimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, EO-modified pentaerythritol tetraacrylate, PO-modified pentaerythritol tetraacrylate, EO-modified ditrimethylolpropane tetraacrylate, PO-modified ditrimethylolpropane tetraacrylate, EO-modified dipentaerythritol hexaacrylate, PO-modified dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, etc.

[0069] Examples of methacrylic compounds that do not contain carboxyl groups and have three or more methacryloyl groups include tris(2-hydroxyethyl)isocyanurate trimethacrylate, trimethylolpropane trimethacrylate, EO-modified trimethylolpropane trimethacrylate, PO-modified trimethylolpropane trimethacrylate, glycerin trimethacrylate, EO-modified glycerin trimethacrylate, PO-modified glycerin trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, and EO-modified glycerin trimethacrylate. Pentaerythritol tetramethacrylate, PO-modified pentaerythritol tetramethacrylate, ditrimethylolpropane tetramethacrylate, EO-modified ditrimethylolpropane tetramethacrylate, PO-modified ditrimethylolpropane tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, EO-modified dipentaerythritol hexamethacrylate, PO-modified dipentaerythritol hexamethacrylate, caprolactone-modified dipentaerythritol hexamethacrylate, etc. can be used.

[0070] In addition to the above, epoxy (meth)acrylates that do not contain carboxyl groups, urethane (meth)acrylates that do not contain carboxyl groups, polyester (meth)acrylates that do not contain carboxyl groups, etc., can also be used.

[0071] The gas barrier properties of organic polymers depend on their free volume and cohesive energy. Free volume refers to the gaps between polymer molecules, and a smaller free volume results in higher gas barrier properties. To suppress the thermal motion of molecules, it is preferable to use resins with high glass transition temperatures and to increase their crosslinking density. (Meth)acrylic resins often have relatively low glass transition temperatures.

[0072] The glass transition temperature of the overcoat layer formed by the active energy ray curable resin composition containing a (meth)acrylic compound is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 60°C or higher, from the viewpoint of gas barrier properties.

[0073] Cohesive energy is the energy related to the magnitude of interaction between functional groups and polar groups with permeate gases. Chlorine groups, fluoro groups, and hydroxyl groups are known to be excellent for oxygen gas, with hydroxyl groups being particularly effective. Therefore, (meth)acrylic compounds containing hydroxyl groups can be used to form organic polymer films with excellent gas barrier properties.

[0074] Examples of hydroxyl group-containing (meth)acrylic compounds include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy-3-phenylpropyl acrylate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxypropyl phthalate, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, 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, tris(2-hydroxyethyl)isocyanurate diacrylate, pentaerythritol triacrylate, dipene You can use methacrylate, pentaerythritol pentaacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenylpropyl methacrylate, 2-methacryloyloxyethyl-2-hydroxyethyl phthalate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl methacrylate, glycerin dimethacrylate, 1,6-hexanediylbis(oxy)bis(2-hydroxy-3,1-propanediyl) bismethacrylate, bisphenol A diglycidyl ether methacrylate adduct, glycerin 1,3-diglycerolate dimethacrylate, tris(2-hydroxyethyl)isocyanurate methacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentamethacrylate, etc.

[0075] The active energy ray-curable resin composition may contain two or more (meth)acrylic compounds. In the first embodiment, the active energy ray-curable resin composition contains two or more carboxyl group-containing (meth)acrylic compounds having a carboxylic acid equivalent of less than 300.

[0076] The first form, for example, is a combination of two or more carboxyl group-containing monofunctional (meth)acrylic compounds having a carboxylic acid equivalent of less than 300 and one (meth)acryloyloxyethyl group.

[0077] The first form, according to other examples, is a combination of a carboxyl group-containing (meth)acrylic compound with a carboxylic acid equivalent of 100 to 250 and a carboxyl group-containing (meth)acrylic compound with a carboxylic acid equivalent of 150 to less than 300. This combination is more preferable from the viewpoint of gas barrier properties compared to combinations of two or more compounds with carboxylic acid equivalents in the range of 100 to less than 150, or combinations of two or more compounds with carboxylic acid equivalents in the range of more than 250 to less than 300.

[0078] The first form, according to further examples, is a combination of a carboxyl group-containing (meth)acrylic compound without a cyclic structure and having a carboxylic acid equivalent of less than 300, and a carboxyl group-containing (meth)acrylic compound with a cyclic structure and having a carboxylic acid equivalent of less than 300. In this combination, the cyclic structure of the carboxyl group-containing (meth)acrylic compound having a cyclic structure can be either an alicyclic or an aromatic ring, but from the viewpoint of barrier properties, an alicyclic ring is more preferable. The reason why the barrier properties are particularly improved when the cyclic structure is alicyclic in this combination is not entirely clear, but it is presumed that when an alicyclic structure is present, it can suppress the thermal motion of the entire interior of the film, and because it is a more flexible cyclic structure than an aromatic ring, it mixes well with the carboxyl group-containing (meth)acrylic compound without a cyclic structure, forming a denser internal structure.

[0079] The blending mass ratio (X1:X2) of a carboxyl group-containing (meth)acrylic compound (X1) without a cyclic structure and having a carboxylic acid equivalent of less than 300, and a carboxyl group-containing (meth)acrylic compound (X2) having a cyclic structure and having a carboxylic acid equivalent of less than 300, is in the range of 80:20 to 5:95 in one example, in the range of 69:31 to 7:93 in another example, and in yet another example, in the range of 51:49 to 9:91.

[0080] In its second form, the active energy ray curable resin composition contains one or more carboxyl group-containing (meth)acrylic compounds having a carboxylic acid equivalent of less than 300, and one or more carboxyl group-free (meth)acrylic compounds. Examples of carboxyl group-free (meth)acrylic compounds that are preferable to use in combination with carboxyl group-containing (meth)acrylic compounds having a carboxylic acid equivalent of less than 300 are as follows:

[0081] The number of acryloyl groups contained in one molecule of an acrylic compound of a (meth)acrylic compound that does not contain a carboxyl group may be in the range of 1 to 15. Having one or more acryloyl groups allows for a curing reaction, while having 15 or fewer 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, and makes it easier to ensure gas barrier properties. From this viewpoint, the number of acryloyl groups may be in the range of 1 to 10, in the range of 2 to 6, or in the range of 3 to 6.

[0082] The number of hydroxyl groups in one molecule of an acrylic compound that does not contain a carboxyl group may be in the range of 0 to 20. Acrylic compounds do not need to contain hydroxyl groups, but the presence of hydroxyl groups improves the balance of interactions within the coating by the hydroxyl groups, making it easier to improve gas barrier properties. Having 20 or fewer hydroxyl groups makes it easier to maintain an appropriate viscosity of the acrylic compound. This results in good coating properties and makes it easier to form a homogeneous coating. From this viewpoint, the number of hydroxyl groups may be in the range of 1 to 15, or in the range of 3 to 10.

[0083] The molecular weight of a (meth)acrylic compound that does not contain a carboxyl group may be less than 300. A molecular weight of less than 300 is preferable from the viewpoint of coating properties and compatibility with carboxyl group-containing (meth)acrylic compounds having a carboxylic acid equivalent of less than 300.

[0084] Examples of (meth)acrylic compounds that do not contain a carboxyl group include, for example, glycerin diacrylate, glycerin triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, N-succinimidyl acrylate, N-acryloyloxyethyl hexahydrophthalimide, 2-hydroxy-3-phenoxypropyl acrylate, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, diethylene glycol diacrylate, triethylene glycol diacrylate, and dipropylene glycol diacrylate, with glycerin diacrylate being particularly preferred.

[0085] The content of the carboxyl group-containing (meth)acrylic compound is, based on the total mass of the (meth)acrylic compound contained in the active energy ray curable resin composition, in one example it is in the range of 5% to 100% by mass, in another example it is in the range of 10% to 100% by mass, in yet another example it is in the range of 30% to 100% by mass, in yet another example it is in the range of 50% to 100% by mass, in yet another example it is in the range of 70% to 100% by mass, and in yet another example it is 100% by mass.

[0086] The content of carboxyl group-containing (meth)acrylic compounds with a carboxylic acid equivalent of less than 300 is, based on the total mass of (meth)acrylic compounds contained in the active energy ray-curable resin composition, in one example it is in the range of 5% to 100% by mass, in another example it is in the range of 10% to 100% by mass, in yet another example it is in the range of 30% to 100% by mass, in yet another example it is in the range of 86% to 100% by mass, in yet another example it is in the range of 96% to 100% by mass, and in yet another example it is 100% by mass.

[0087] From the viewpoint of adhesion and gas barrier properties, the active energy ray curable resin composition may contain a carboxyl group-containing (meth)acrylic compound in an amount of 50% to 100% by mass, 70% to 100% by mass, or 80% to 100% by mass.

[0088] The active energy ray curable resin composition may further contain additives such as a photoradical generator and a silane coupling agent.

[0089] The active energy ray curable resin composition may contain a photoradical generator. Any photoradical generator capable of generating radicals by irradiation with EB or UV can be used. The photoradical generator is not particularly limited, but examples include benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphate, camphorquinone, 9-fluorenone, and diphenyl disulfide.

[0090] The active energy ray curable resin composition may contain a silane coupling agent. 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-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane.

[0091] The thickness of the overcoat layer 3 is set according to the required performance, and can be, for example, 0.05 μm to 10 μm, 0.1 μm to 5 μm, 0.15 μm to 2 μm, 0.2 μm to 2 μm, or 0.3 μm to 1 μm. From the viewpoint of gas barrier properties, the thickness of the overcoat layer 3 is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.15 μm or more. On the other hand, if it is too thick, it will take a long time to cure, so the thickness of the overcoat layer 3 is preferably 10 μm or less, and more preferably 5 μm or less.

[0092] <Variation> The gas barrier film can be subjected to various deformations. As described above, the gas barrier film according to this embodiment may further include an underlayer not shown in Figure 1.

[0093] Modified examples are described below with reference to Figure 2. Note that the points described with reference to Figure 1 can be applied individually or in combination to the gas barrier films related to the modified examples described herein.

[0094] Figure 2 is a cross-sectional view of a gas barrier film according to one modified example. The gas barrier film 20 shown in Figure 2 comprises a base layer 1, an undercoat layer 4, an inorganic oxide layer 2, and an overcoat layer 3 in that order. Except for the inclusion of the undercoat layer 4 between the base layer 1 and the inorganic oxide layer 2, it is the same as the gas barrier film 10 described with reference to Figure 1. By providing the undercoat layer 4, the smoothness of the surface of the base layer 1 is improved, which in turn improves the film quality of the inorganic oxide layer formed thereon, further enhancing the gas barrier properties of the gas barrier film 20.

[0095] [Base layer] The base layer 4 contains an organic polymer. The base layer 4 may further contain a silane coupling agent, organic titanate, modified silicone oil, etc. The content of the organic polymer in the base layer 4 may be, for example, 70% by mass or more, or 80% by mass or more.

[0096] Examples of organic polymers include polyacrylic resins, polyester resins, polycarbonate resins, polyol resins, polyurethane resins, polyamide resins, polyolefin resins, polyimide resins, melamine resins, and phenolic resins. Considering the heat and water resistance of the adhesion strength between the base layer 1 and the inorganic oxide layer 2, it is preferable that the underlayer 4 contains at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers.

[0097] More preferably, the organic polymers are those having urethane bonds formed by the reaction of polyols having two or more hydroxyl groups at their molecular ends or in their molecular chains with an isocyanate compound, or organic polymers containing reaction products of polyols having two or more hydroxyl groups at their molecular ends or in their molecular chains with a silane coupling agent, or an organic silane compound such as its hydrolysate. Either one or both of these may be used.

[0098] Examples of the polyols mentioned above include at least one selected from acrylic polyols, polyvinyl acetals, polystyrene polyols, and polyurethane polyols. Acrylic polyols may be obtained by polymerizing acrylic acid derivative monomers, or by copolymerizing acrylic acid derivative monomers with other monomers. Examples of acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers copolymerized with acrylic acid derivative monomers include styrene.

[0099] Isocyanate compounds enhance adhesion between the substrate layer 1 and the inorganic oxide layer 2 through urethane bonds formed by reaction with polyols. In other words, isocyanate compounds function as crosslinking agents or curing agents. Examples of isocyanate compounds include monomers such as 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), polymers thereof, and derivatives thereof, which are so-called polyisocyanates having two or more isocyanate groups in their molecules. The above-mentioned isocyanate compounds may be used individually or in combination of two or more.

[0100] Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidooxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. The organosilane compound may be a hydrolysate of these silane coupling agents. The organosilane compound may contain one of the above-mentioned silane coupling agents and their hydrolysates alone, or in combination of two or more.

[0101] The base layer 4 can be formed using a base layer forming coating agent consisting of a mixture of the above-mentioned components in an organic solvent in any proportion. This coating agent may contain, for example, curing accelerators such as tertiary amines, imidazole derivatives, metal salt compounds of carboxylic acids, quaternary ammonium salts, and quaternary phosphonium salts; antioxidants such as phenolic, sulfuric, and phosphite-based agents; leveling agents; flow regulators; catalysts; crosslinking reaction accelerators; fillers, etc.

[0102] The thickness of the base layer 4 can be set appropriately according to the application or required properties, for example, within the range of 0.005 μm to 5 μm. For example, the thickness of the base layer 4 is preferably within the range of 0.01 μm to 1 μm, and more preferably within the range of 0.01 μm to 0.5 μm. If the thickness of the base layer 4 is 0.01 μm or more, sufficient adhesion strength between the substrate layer 1 and the inorganic oxide layer 2 is easily obtained, and gas barrier properties are also good. If the thickness of the base layer 4 is 1 μm or less, a uniform coated surface is easily formed, and drying load and manufacturing costs can be suppressed.

[0103] <Method for manufacturing gas barrier film> The gas barrier film according to this embodiment can be manufactured by a manufacturing method that includes forming an inorganic oxide layer on a substrate layer, forming a coating film of an active energy ray-curable resin composition on the inorganic oxide layer, and irradiating the obtained coating film with active energy rays to form an overcoat layer consisting of a cured product of the active energy ray-curable resin composition. This manufacturing method may further include forming other layers, such as a base layer, as needed.

[0104] As an example of a method for manufacturing a gas barrier film according to this embodiment, the method for manufacturing the gas barrier film 20 shown in Figure 2 will be described below.

[0105] In the method for manufacturing the gas barrier film 20, the underlayer 4 is formed on the base layer 1. The base layer 1 may be a commercially available product or one manufactured by a known method. The underlayer 4 can be formed by applying the above-mentioned underlayer forming coating agent onto the base layer 1 by a wet coat method and drying the formed coating film. By drying the formed coating film, the solvent is removed and hardening progresses, forming the underlayer 4.

[0106] As a method for applying the coating agent, known wet coating methods can be used. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating.

[0107] As a method for drying the coating film, known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used. The drying temperature of the coating film can be, for example, in the range of 50 to 200°C. The drying time varies depending on the thickness of the coating film, the drying temperature, etc., but can be, for example, in the range of 1 second to 5 minutes. The drying conditions of the coating film should be appropriately determined considering the ease with which the solvent in the coating film dries, the thermal stability of the substrate layer 1, etc.

[0108] Next, an inorganic oxide layer 2 is formed on the underlayer 4. The inorganic oxide layer 2 can be formed by the vacuum deposition method, sputtering method, ion plating method, or plasma vapor deposition (CVD) method described above.

[0109] Next, an overcoat layer 3 is formed. The overcoat layer 3 can be formed, for example, by applying the above-mentioned active energy ray curable resin composition as an overcoat layer forming coating agent to the inorganic oxide layer 2 by a wet coating method to form a coating film, and then curing the coating film by EB irradiation or UV irradiation.

[0110] The irradiation conditions for the active energy rays depend on the thickness of the overcoat layer 3, but for example, the acceleration voltage can be set to 10 to 300 kV and the irradiation dose to 15 to 120 kGy. If the acceleration voltage is within the above range, the active energy rays can easily penetrate sufficiently deep into the thickness direction of the coating film, and the deterioration of the inorganic oxide layer 2, the undercoat layer 4, and the substrate layer 1 due to the active energy rays can be easily suppressed. Also, if the irradiation dose is within the above range, yellowing of the overcoat layer 3 and changes in its mechanical properties can be easily suppressed.

[0111] The method for applying the coating agent can be the same as that described in the explanation of the process for forming the base layer 4. The overcoat layer 3 may be formed by a single application and curing, or it may be formed by repeating the application and curing process multiple times using the same type of coating agent or different types of coating agents.

[0112] <Packaging materials> The gas barrier films 10 and 20 described above can be used in packaging materials. Figure 3 is a cross-sectional view showing an example of a packaging material containing the gas barrier film of Figure 1. The packaging material 30 shown in Figure 3 includes the gas barrier film 10, a heat-sealable layer 6, and an adhesive layer 5.

[0113] [Heat fusion layer] The heat-sealable layer 6 faces the overcoat layer 3 of the gas barrier film 10. The heat-sealable layer 6 preferably contains a polypropylene film, and more preferably consists of a polypropylene film. By making both the base layer 1 and the heat-sealable layer 6 from polypropylene, the polypropylene content in the packaging material 30 can be set to 90% by mass or more. As a result, the packaging material 30 becomes a so-called monomaterial material with excellent recyclability. The heat-sealable layer 6 is preferably an unoriented polypropylene film (CPP).

[0114] [Adhesive layer] The adhesive layer 5 is interposed between the overcoat layer 3 and the heat-sealing layer 6 of the gas barrier film 10, bonding them together. The adhesive layer 5 may be omitted.

[0115] Known adhesives such as polyurethane adhesives, polyester adhesives, and polyether adhesives can be used to form the adhesive layer 5. The adhesive layer 5 can be formed by applying it onto the heat-sealable layer 6 using known methods such as dry lamination or extrusion lamination, and then drying the coating film.

[0116] [Other layers] The packaging material 30 may further include one or more other layers. Other layers include, for example, a printing layer, a protective layer, a light-shielding layer, an adhesive layer, and other functional layers.

[0117] <Package> The above-described packaging material 30 can be used in a package. For example, the packaging is a bag such as a flat pouch, a standing pouch, or a gusseted pouch. The bag can be manufactured by overlapping the peripheral edges of one or more film pieces cut from the packaging material 30 so that the heat-sealable layers 6 come into contact with each other and then heat-sealing them.

[0118] In other examples, the packaging includes a container body having an opening and a lid that closes this opening. A film piece cut from the packaging material 30 can be used as the lid.

[0119] <Packaged goods> The packaged article includes the packaging body described above and the article contained therein. The article contained therein may be a liquid, a solid, or a mixture thereof. The article contained therein may be, for example, food or medicine. [Examples]

[0120] The tests conducted in connection with the present invention are described below. (1) Test 1 (1.1) Manufacturing of gas barrier films (Example 1) The gas barrier film 10 shown in Figure 1 was manufactured by the following method. First, as the base layer 1, a 20 μm thick biaxially oriented polypropylene film (VPH2011, manufactured by AJPlast) with one side treated with corona was prepared.

[0121] Using an electron beam heating vacuum deposition apparatus, a mixed material containing two or more elements, such as metallic silicon, silicon monoxide, and silicon dioxide, was evaporated to form a 30 nm thick inorganic oxide layer 2 consisting of a silicon oxide deposition film on the corona-treated surface of the substrate layer 1.

[0122] A coating solution (active energy ray curable resin composition) consisting of 2-acryloyloxyethyl succinic acid (product name: HOA-MS(N), manufactured by Kyoeisha Chemical Co., Ltd.) (compound a) was applied to the inorganic oxide layer 2 using a flexographic printing press to form a coating film. Next, using an electron beam irradiation device manufactured by I-Electron Beam Co., Ltd., the obtained coating film was cured by EB irradiation under a nitrogen atmosphere with an acceleration voltage of 120 kV, an irradiation dose of 15 kGy, and an oxygen concentration of 100 ppm or less, thereby forming an overcoat layer 3 with a thickness of 1 μm. As described above, the gas barrier film 10 shown in Figure 1 was obtained.

[0123] (Example 2) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-methacryloyloxyethyl succinic acid (product name: Light Ester HOMS(N), manufactured by Kyoeisha Chemical Co., Ltd.) (compound b).

[0124] (Example 3) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with carboxyethyl acrylate (product name: 2-Carboxyethyl acrylate, manufactured by Sigma-Aldrich) (compound c).

[0125] (Example 4) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-methacryloyloxyethyl maleate (product name: mono-2-(Methacryloxy)ethyl maleate, manufactured by Sigma-Aldrich) (compound d).

[0126] (Example 5) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-methacryloyloxyethyl phthalate (product name: Mono-2-(methacryloxy)ethyl Phthalate, manufactured by Tokyo Chemical Industry Co., Ltd.) (compound e).

[0127] (Example 6) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-acryloyloxyethyl phthalic acid (product name: M-5400, manufactured by Toagosei) (compound f).

[0128] (Example 7) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-acryloyloxyethyl hexahydrophthalic acid (product name: Light Acrylate HOA-HH(N), manufactured by Kyoeisha Chemical Co., Ltd.) (compound g).

[0129] (Comparative Example 1) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 4-hydroxybutyl acrylate (product name: 4-hydroxybutyl acrylate, manufactured by Kanto Chemical Co., Ltd.) (compound h).

[0130] (Comparative Example 2) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with dipropylene glycol diacrylate (product name: Dipropylene Glycol Diacrylate, manufactured by Tokyo Chemical Industry Co., Ltd.) (compound i).

[0131] (Comparative Example 3) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with tricyclodecanedimethanol diacrylate (product name: Light Acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) (compound j).

[0132] (Comparative Example 4) A gas barrier film was obtained by the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with 2-hydroxy-3-phenoxypropyl acrylate (product name: epoxy ester M-600A, manufactured by Kyoeisha Chemical Co., Ltd.) (compound k).

[0133] (Comparative Example 5) A gas barrier film was obtained by the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with tris(2-hydroxyethyl)isocyanurate triacrylate (product name: A-9300, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) (compound l).

[0134] (Comparative Example 6) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with glycerin diacrylate (product name: Aronics® M-920, manufactured by Toagosei) (compound m).

[0135] (Comparative Example 7) A gas barrier film was obtained using the same method as in Example 1, except that the overcoat layer 3 was not formed.

[0136] The (meth)acrylic compounds used in Examples 1 to 7 and Comparative Examples 1 to 6 are summarized below along with their carboxylic acid equivalents. For compounds without a carboxyl group, the molecular weight is listed instead of the carboxylic acid equivalent.

[0137] [ka]

[0138] [ka]

[0139] (1.2) Measurement and evaluation (curable) For each of the above gas barrier films, excluding Comparative Example 7, the curability was evaluated by the tackiness when the overcoat layer was rubbed with a latex glove. A rating was given when no rubbing marks were left on the overcoat layer and no stickiness was observed, while a rating of B was given when rubbing marks were left on the overcoat layer or when stickiness was observed. The results are shown in Table 1. Note that the rating of B for the curability of Comparative Example 1 was due to the observation of stickiness on the surface of the overcoat layer.

[0140] (Oxygen barrier properties) Using an oxygen permeability measuring device (product name: OXTRAN®-2 / 20, manufactured by MOCON), the oxygen permeability (cc / (m³)) of each of the above gas barrier films was measured under an atmosphere of 30°C and 70% RH (relative humidity). 2 The oxygen permeability (day·atm) was measured. A lower oxygen permeability indicates better oxygen barrier properties. The results are shown in Table 1. Note that for Comparative Example 1, which received a curing performance evaluation of B, oxygen barrier properties were not evaluated because it was difficult to handle due to the stickiness of the overcoat layer surface.

[0141] (Adhesion) For each of the above gas barrier films, excluding Comparative Example 7, adhesion was evaluated using the "X-cut tape method" of JIS K 5400. Specifically, a thin cross-shaped cut was made in the overcoat layer with a cutter, and after applying tape and peeling it off, the adhesion was evaluated on a score (0 to 10 points) based on the amount of overcoat layer remaining on the gas barrier film. Specifically, a score of 0 was given if the peeling was larger than the cross-cut area, a score of 10 was given if there was no peeling at all, and the scores in between were given 2, 4, 6, and 8 points according to the degree of peeling, from worst adhesion to worst adhesion, for a total of 6 levels of evaluation. Based on the results, a score of A was given if there was no peeling at all (10 points), and a score of B was given for all other cases (0, 2, 4, 6, 8 points). The evaluation results based on this standard are shown in Table 1.

[0142] [Table 1]

[0143] As shown in Table 1, all of Examples 1 to 7, which used carboxyl group-containing (meth)acrylic compounds, exhibited excellent curability, adhesion, and oxygen barrier properties. In contrast, Comparative Examples 2 to 6, excluding Comparative Example 1 where oxygen permeability could not be measured due to stickiness, showed improved oxygen barrier properties compared to Comparative Example 7, which did not have an overcoat layer, but all exhibited poor adhesion.

[0144] These results suggest that using carboxyl group-containing (meth)acrylic compounds improved adhesion because the carboxyl groups in the coating formed by active energy ray curing interacted with the underlying inorganic oxide layer. Furthermore, the carboxyl group-containing (meth)acrylic compounds used in Examples 1 to 7, although monofunctional, exhibited excellent oxygen barrier properties. These results suggest that the interaction between carboxyl groups led to the formation of pseudo-crosslinks between polymers in the coating, thereby improving oxygen barrier properties.

[0145] Furthermore, Examples 5 to 7, which used carboxyl group-containing (meth)acrylic compounds with a cyclic structure, exhibited superior oxygen barrier properties compared to Examples 1 to 4, which used carboxyl group-containing (meth)acrylic compounds without a cyclic structure. This is thought to be because the presence of a relatively rigid cyclic structure suppresses the thermal motion of polymer chains in the coating, making it difficult for oxygen molecules to permeate.

[0146] (2) Test example 2 (2.1) Manufacturing of gas barrier films (Example 8) A gas barrier film was obtained by the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with a mixture of 2-acryloyloxyethyl succinic acid (compound a) and 2-acryloyloxyethyl hexahydrophthalic acid (compound g) (mass ratio: a / g = 30 / 70).

[0147] (Example 9) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with a mixture of 2-acryloyloxyethyl succinic acid (compound a) and 2-acryloyloxyethyl phthalic acid (compound f) (mass ratio: a / f = 50 / 50).

[0148] (Example 10) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with a mixture of 2-acryloyloxyethyl phthalic acid (compound f) and 2-acryloyloxyethyl hexahydrophthalic acid (compound g) (mass ratio: f / g = 50 / 50).

[0149] (Example 11) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with a mixture of 2-acryloyloxyethyl succinic acid (compound a) and glycerin diacrylate (compound m) (mass ratio: a / m = 70 / 30).

[0150] (Example 12) A gas barrier film was obtained using the same method as in Example 1, except that 2-acryloyloxyethyl succinic acid (compound a) was replaced with a mixture of 2-acryloyloxyethyl succinic acid (compound a) and glycerin diacrylate (compound m) (mass ratio: a / m = 50 / 50).

[0151] (2.2) Measurement and evaluation For each of the above gas barrier films, the curability, adhesion, and oxygen barrier properties were evaluated using the same method as in Test 1. The results are shown in Table 2.

[0152] [Table 2]

[0153] Examples 8 to 10 are examples of the combined use of two carboxyl group-containing (meth)acrylic compounds with a carboxylic acid equivalent of less than 300. Examples 8 and 9 are combinations of a compound without a cyclic structure and a compound with a cyclic structure, respectively, and are also combinations of a compound with a carboxylic acid equivalent of 100 to 250 and a compound with a carboxylic acid equivalent of 150 to less than 300 as described above. Example 10 is a combination of two compounds with a cyclic structure, and is also a combination of two compounds with a carboxylic acid equivalent of 150 to less than 300.

[0154] Tables 1 and 2 show that oxygen barrier properties can be further improved by using a combination of two or more carboxyl group-containing (meth)acrylic compounds, selected from two or more carboxylate equivalents with a carboxylic acid equivalent of less than 300, based on the presence or absence of a ring structure or the carboxylic acid equivalent.

[0155] Examples 11 and 12 are examples of the combined use of a carboxyl group-containing (meth)acrylic compound with a carboxylate equivalent of less than 300 and a carboxyl group-free (meth)acrylic compound. From Tables 1 and 2, it can be seen that the oxygen barrier properties are further improved by combining the carboxyl group-containing (meth)acrylic compound with other (meth)acrylic compounds compared to the use of the carboxyl group-containing (meth)acrylic compound alone.

[0156] (3) Test example 3 (3.1) Manufacturing of gas barrier films (Example 13) A gas barrier film was obtained using the same method as in Example 1, except that the thickness of the overcoat layer was changed from 1 μm to 0.5 μm.

[0157] (Example 14) A gas barrier film was obtained using the same method as in Example 1, except that the thickness of the overcoat layer was changed from 1 μm to 0.2 μm.

[0158] (Example 15) A gas barrier film was obtained using the same method as in Example 7, except that the thickness of the overcoat layer was changed from 1 μm to 0.5 μm.

[0159] (Example 16) A gas barrier film was obtained using the same method as in Example 7, except that the thickness of the overcoat layer was changed from 1 μm to 0.2 μm.

[0160] (Comparative Example 8) A gas barrier film was obtained using the same method as in Comparative Example 5, except that the thickness of the overcoat layer was changed from 1 μm to 0.5 μm.

[0161] (Comparative Example 9) A gas barrier film was obtained using the same method as in Comparative Example 5, except that the thickness of the overcoat layer was changed from 1 μm to 0.2 μm.

[0162] (3.2) Measurement and evaluation For each of the above gas barrier films, the curability, adhesion, and oxygen barrier properties were evaluated using the same method as in Test 1. The results are shown in Table 3.

[0163] [Table 3]

[0164] As shown in Table 3, all of Examples 13 to 16, in which the thickness of the overcoat layer was reduced compared to Examples 1 and 7, exhibited superior curability, oxygen barrier properties, and adhesion.

[0165] Furthermore, in Comparative Examples 7 and 8, where the thickness of the overcoat layer was reduced compared to Comparative Example 5, which used a (meth)acrylic compound without a carboxyl group, the stress difference with the inorganic oxide layer should have been reduced due to the thinner overcoat layer, but the adhesion was still poor. [Explanation of Symbols]

[0166] 1...Substrate, 2...Inorganic oxide layer, 3...Overcoat layer, 4...Undercoat layer, 5...Adhesive layer, 6...Heat-sealable layer, 10...Gas barrier film, 20...Gas barrier film, 30...Packaging material.

Claims

1. The substrate layer, the inorganic oxide layer, and the overcoat layer are provided in this order. The aforementioned overcoat layer is a cured product of an active energy ray curable resin composition. The aforementioned active energy ray-curable resin composition is a gas barrier film containing a carboxyl group-containing (meth)acrylic compound.

2. The gas barrier film according to claim 1, wherein the carboxyl group-containing (meth)acrylic compound comprises a carboxyl group-containing (meth)acrylic compound with a carboxylic acid equivalent of less than 300.

3. The gas barrier film according to claim 1, wherein the carboxyl group-containing (meth)acrylic compound comprises a carboxyl group-containing (meth)acrylic compound having a cyclic structure.

4. The gas barrier film according to claim 1, comprising a carboxyl group-containing (meth)acrylic compound having an alicyclic structure.

5. The gas barrier film according to claim 1, wherein the carboxyl group-containing (meth)acrylic compound comprises a monofunctional carboxyl group-containing (meth)acrylic compound having one (meth)acryloyl group.

6. The carboxyl group-containing (meth)acrylic compound is a gas barrier film according to claim 1, having a (meth)acryloyloxyethyl group.

7. The gas barrier film according to claim 1, wherein the carboxyl group-containing (meth)acrylic compound comprises two or more carboxyl group-containing (meth)acrylic compounds with a carboxylic acid equivalent of less than 300.

8. The gas barrier film according to claim 1, wherein the base layer comprises a polyolefin resin.

9. The gas barrier film according to claim 1, wherein the overcoat layer has a thickness in the range of 0.05 μm to 10 μm.

10. A gas barrier film according to any one of claims 1 to 9, A heat-sealable layer provided on the overcoat layer of the gas barrier film and Packaging material equipped with [specific features / features].

11. A package containing the packaging material described in claim 10.

12. A packaged article comprising a packaging body according to claim 11 and an article contained in the packaging body.

13. Forming an inorganic oxide layer on a substrate layer, Forming a coating film of an active energy ray-curable resin composition on the inorganic oxide layer, By irradiating the coating film with active energy rays, an overcoat layer consisting of a cured product of the active energy ray-curable resin composition is formed. The active energy ray curable resin composition includes a method for producing a gas barrier film containing a carboxyl group-containing (meth)acrylic compound.

14. The method for producing the product according to claim 13, wherein the carboxyl group-containing (meth)acrylic compound comprises a carboxyl group-containing (meth)acrylic compound having a carboxylic acid equivalent of less than 300.

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