Epoxy film, epoxy film with substrate film, manufacturing method of epoxy film and its application

Abstract

To provide an epoxy film without loss of transparency and minimal curling.SOLUTION: An epoxy film includes an epoxy resin layer and an active energy ray-cured resin layer. The epoxy resin layer includes an epoxy resin (A) and an isocyanate compound-derived unit (B). The active energy ray-cured resin layer includes a urethane methacrylate constitutional unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy film, an epoxy film with a base film, a wound body, a base sheet, and a method for producing an epoxy film. [Background technology]

[0002] Epoxy resins are used in a variety of fields, such as paints, civil engineering, adhesives, and electronic components, due to their excellent heat resistance, adhesive properties, water resistance, mechanical strength, and electrical properties.

[0003] For example, Patent Document 1 discloses a curable resin composition using a specific polymer polyether polyol resin, a tri- or higher functional epoxy resin, and an epoxy resin curing agent, and describes that the cured product obtained by curing the composition has excellent heat resistance and bending resistance, and is therefore applicable to foldable OLED displays. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 080292 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when forming a cured product from the curable resin composition described in Patent Document 1, the curing time is long, 1 hour, and it has been found that, due to the long curing time at high temperature, the components of the release layer may be transferred to the epoxy layer, resulting in a loss of transparency.

[0006] Furthermore, when an epoxy resin film is used for electronic components, a functional layer such as a hard coat layer or wiring may be provided on the film in a later process, and therefore the surface of the film is required to have good wettability with respect to the functional layer or wiring. However, it has been found that when a film is formed by applying a coating liquid of an epoxy resin composition to a substrate film, the longer the time required for curing the epoxy resin composition, the more the release component of the substrate film is transferred to the epoxy resin layer, resulting in an increase in the water droplet contact angle on the surface of the substrate film, which may cause problems such as poor adhesion in subsequent processes.

[0007] Therefore, the present inventors attempted to use an isocyanate compound to enable epoxy resin to be cured in a short time. However, epoxy resin films obtained by heat-curing an epoxy resin and an isocyanate compound have a problem in that they curl when subjected to a heating test at a temperature below the glass transition point.

[0008] If the film curls due to heating, it may cause problems during post-processing such as coating or lamination.

[0009] In view of the above, an object of the present invention is to obtain an epoxy film that is highly transparent and suppresses the occurrence of curling. [Means for solving the problem]

[0010] In order to solve the above problems, the present inventors conducted further research and found that because isocyanate can react with moisture in the air, a difference occurs in the crosslink density between the side that comes into contact with the air (the side not adjacent to the substrate) and the side that comes into contact with the substrate (the side adjacent to the substrate) when the solvent dries; more specifically, the crosslink density is lower on the side not adjacent to the substrate, and the difference in the degree of curing on both surfaces becomes a difference in stress, resulting in curling.

[0011] Furthermore, the present inventors have found that the problem of curling can be solved by providing an active energy ray-cured resin layer formed from an active energy ray-curable resin composition as a layer that relieves the shrinkage stress that occurs during curing of the epoxy resin layer due to the above mechanism.

[0012] That is, the present invention has the following aspects.

[0013] [1] A first aspect of the present invention is an epoxy film having an epoxy resin layer and an active energy ray-cured resin layer, wherein the epoxy resin layer contains an epoxy resin (A) and an isocyanate compound-derived unit (B), and the active energy ray-cured resin layer contains a urethane (meth)acrylate structural unit.

[0014] [2] A second aspect of the present invention is the epoxy film of the first aspect, wherein the thickness of the epoxy resin layer is 1 to 1000 μm, and the thickness of the active energy ray-cured resin layer is 0.5 to 20 μm.

[0015] [3] A third aspect of the present invention is the epoxy film according to the first or second aspect, wherein P / Q is 1 to 100, where P is the thickness of the epoxy resin layer and Q is the thickness of the active energy ray-cured resin layer.

[0016] [4] A fourth aspect of the present invention is the epoxy film according to any one of the first to third aspects, wherein the epoxy resin (A) is a resin obtained by reacting an epoxy compound and a phenolic compound.

[0017] [5] A fifth aspect of the present invention is the epoxy film according to the fourth aspect, wherein the epoxy compound is a compound having two or more epoxy groups in the molecule.

[0018] [6] A sixth aspect of the present invention is the epoxy film according to the fourth or fifth aspect, wherein the phenolic compound is a compound having two or more hydroxyl groups bonded to an aromatic ring.

[0019] [7] A seventh aspect of the present invention is the epoxy film according to any one of the first to sixth aspects, wherein the isocyanate compound-derived units (B) are units derived from a compound having an aliphatic isocyanate as a main skeleton.

[0020] [8] An eighth aspect of the present invention is the epoxy film according to any one of the first to seventh aspects, wherein the epoxy resin layer further contains a leveling agent.

[0021] [9] A ninth aspect of the present invention is the epoxy film according to any one of the first to eighth aspects, wherein the glass transition temperature of the epoxy resin layer is 100° C. or higher.

[0022]

[10] A tenth aspect of the present invention is an epoxy film according to any one of the first to ninth aspects, further comprising a functional layer on at least one surface thereof.

[0023]

[11] An eleventh aspect of the present invention is an epoxy film with a base film, comprising the epoxy film of any one of the first to tenth aspects and a base film, and an epoxy resin layer laminated on the base film via the active energy ray-cured resin layer.

[0024]

[12] A twelfth aspect of the present invention is a wound body obtained by winding the epoxy film according to any one of the first to tenth aspects or the epoxy film with a base film according to the eleventh aspect around a core.

[0025]

[13] A thirteenth aspect of the present invention is a method for producing an epoxy film, comprising: a step of curing an active energy ray-curable resin composition containing a urethane (meth)acrylate oligomer to form an active energy ray-cured resin layer; and a step of applying an epoxy resin composition containing an epoxy resin (A) and an isocyanate compound (B) onto the active energy ray-cured resin layer and curing the composition to form an epoxy resin layer.

[0026]

[14] A fourteenth aspect of the present invention is the method for producing an epoxy film according to the thirteenth aspect, wherein the epoxy resin (A) has a mass average molecular weight of 2,000 to 300,000.

[0027]

[15] A fifteenth aspect of the present invention is the method for producing an epoxy film according to the thirteenth or fourteenth aspect, wherein the isocyanate compound (B) is a compound having an aliphatic isocyanate as a main skeleton.

[0028]

[16] A sixteenth aspect of the present invention is the method for producing an epoxy film according to any one of the thirteenth to fifteenth aspects, wherein the epoxy resin composition further contains a leveling agent.

[0029]

[17] A seventeenth aspect of the present invention is a base sheet for laminating an epoxy resin layer containing an epoxy resin (A) and an isocyanate compound-derived unit (B), the base sheet including an active energy ray-cured resin layer containing a urethane (meth)acrylate structural unit. [Effects of the Invention]

[0030] According to the present invention, an epoxy film having high transparency and suppressed curling can be obtained. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic diagram of a cross section of an epoxy film with a base film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] An embodiment of the present invention will be described below. However, the present invention is not limited to the embodiment described below, and various modifications are possible without departing from the gist of the present invention. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits.

[0033] <<Epoxy film>> The epoxy film of the present invention (hereinafter also referred to as "the film") has an epoxy resin layer and an active energy ray-cured resin layer. In the film, the active energy ray-cured resin layer and the epoxy resin layer are preferably directly laminated. The film preferably has the epoxy resin layer formed on the active energy ray-cured resin layer.

[0034] The epoxy resin layer of this film contains an isocyanate compound to enable rapid curing and enhance film transparency. However, the present inventors discovered that because isocyanate can react with moisture in the air, a difference in crosslink density occurs between the surface in contact with the air (the surface not adjacent to the substrate) and the surface in contact with the substrate (the surface adjacent to the substrate) during solvent drying. More specifically, the crosslink density on the surface not adjacent to the substrate becomes lower, and the difference in curing degree between the two surfaces results in a difference in stress, resulting in curling. Therefore, after extensive research, the present inventors discovered that by further providing an active energy ray-cured resin layer in this film, the tough active energy ray-cured resin layer can absorb the shrinkage stress during epoxy resin curing, thereby suppressing curling. This results in the present film having high transparency and curl resistance.

[0035] The present invention may also relate to a substrate film-attached epoxy film having the above-mentioned epoxy film and substrate film, in which the epoxy resin layer is laminated on the substrate film via an active-energy ray-cured resin layer. As shown in FIG. 1 , the substrate film-attached epoxy film 10 includes an epoxy film 5 having an active-energy ray-cured resin layer 2 and an epoxy resin layer 3, and a substrate film 1, and the substrate film 1, in which the substrate film 1, the active-energy ray-cured resin layer 2, and the epoxy resin layer 3 are laminated in this order. In the substrate film-attached epoxy film, the presence of the active-energy ray-cured resin layer between the thermoplastic substrate film and the thermosetting epoxy resin layer reduces stress caused by the difference in linear expansion between the substrate film and the epoxy resin layer during the thermal curing process of the epoxy resin layer, and as a result, it is believed that curling due to heating is more effectively suppressed.

[0036] From this viewpoint, the active energy ray-cured resin layer is preferably formed from an active energy ray-curable resin composition containing a urethane (meth)acrylate oligomer, i.e., the active energy ray-cured resin layer is preferably a layer containing a urethane (meth)acrylate structural unit. Urethane (meth)acrylate can form a strong resin layer by forming hydrogen bonds. Furthermore, the urethane skeleton (-O-CO-NH-) of urethane (meth)acrylate is thought to interact with the isocyanate present in the epoxy resin layer, thereby reducing the difference in crosslink density that causes curling. This mechanism is thought to effectively suppress curling in this film.

[0037] In this specification, the term "(meth)acrylate" encompasses both "acrylate" and "methacrylate." Furthermore, the term "(meth)acryloyl group" encompasses both "methacryloyl group" and "acryloyl group." Furthermore, the term "(co)polymer" encompasses both "polymer" and "copolymer."

[0038] <Actinic energy ray cured resin layer> The active energy ray-cured resin layer (hereinafter also referred to as "main cured layer") is a layer containing a urethane (meth)acrylate structural unit, and is a layer formed by curing an active energy ray-curable resin composition. Examples of active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, ultraviolet rays, and visible light, with ultraviolet rays being preferred.

[0039] The cured product layer may contain, in addition to the urethane (meth)acrylate structural unit, a unit derived from an isocyanate compound, a leveling agent, a photopolymerization initiator, or a unit derived from a photopolymerization initiator. The isocyanate compound, the leveling agent, and the photopolymerization initiator can be appropriately selected from the compounds described below.

[0040] The thickness of the cured material layer is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more, and is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

[0041] The pencil hardness of the active energy ray-cured resin layer is preferably F or higher, and more preferably H or higher. The pencil hardness of the active energy ray-cured resin layer can be evaluated in accordance with JIS K5600-5-4:1999. By setting the pencil hardness of the active energy ray-cured resin layer within the above range, the curl resistance of the epoxy film can be more effectively improved.

[0042] <Active energy ray-curable resin composition> The active energy ray-curable resin composition for forming the present cured product layer contains, for example, a (co)polymer having a (meth)acryloyl group or an oligomer having a (meth)acryloyl group, and may further contain one or more monomers having one or more (meth)acryloyl groups. The active energy ray-curable resin composition may further contain other components such as a leveling agent, a photopolymerization initiator, and a solvent, as necessary.

[0043] Examples of the oligomer having a (meth)acryloyl group include urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, acrylic (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polycarbonate (meth)acrylate oligomers, polybutadiene (meth)acrylate oligomers, and polyether (meth)acrylate. These may be used alone or in combination of two or more.

[0044] The content of the urethane (meth)acrylate in the active energy ray-curable resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on the total mass of the active energy ray-curable resin composition. The content of the urethane (meth)acrylate is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on the total mass of the active energy ray-curable resin composition.

[0045] <Urethane (meth)acrylate oligomer> The urethane (meth)acrylate oligomer may be one produced by a known method using an isocyanate compound, a hydroxyl group-containing (meth)acrylate, a polyol, or the like.

[0046] (Isocyanate compounds) The isocyanate compound used in the production of the urethane (meth)acrylate oligomer is a compound having a total of two or more isocyanate groups or substituents containing an isocyanate group in one molecule. The isocyanate compounds may be used alone or in combination of two or more. Examples of the isocyanate compound include chain aliphatic polyisocyanates, aromatic polyisocyanates, and alicyclic polyisocyanates. These may be used alone or in combination of two or more. In particular, from the viewpoint of increasing the flex resistance and hardness of the active energy ray-cured resin layer, it is preferable to use at least one of a chain aliphatic polyisocyanate and an alicyclic polyisocyanate for producing the urethane (meth)acrylate oligomer.

[0047] (Hydroxyl group-containing (meth)acrylate) Examples of the hydroxyl group-containing (meth)acrylate used in producing the urethane (meth)acrylate oligomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, an addition reaction product of 2-hydroxyethyl (meth)acrylate and caprolactone, an addition reaction product of 4-hydroxybutyl (meth)acrylate and caprolactone, bisphenol A diglycidyl ether diacrylate, trimethylolpropane di(meth)acrylate, mono(meth)acrylate of trimethylolethane di(meth)acrylate glycol, glycerin (meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate.

[0048] In addition to the above, examples of hydroxyl group-containing (meth)acrylates used in producing the urethane (meth)acrylate oligomers include epoxy (meth)acrylates obtained by reacting an epoxy compound selected from epoxy compounds having a chain aliphatic structure, a cyclic aliphatic structure, or an aromatic structure with a compound having a (meth)acryloyl group and a carboxyl group, such as hydroxyalkyl (meth)acrylates having an alkylene group having 2 to 4 carbon atoms between the (meth)acryloyl group and the hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate. These may be used alone or in combination of two or more. In particular, from the viewpoint of improving the adhesiveness, solvent resistance, etc. of the active energy ray-cured resin layer, at least one selected from trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate can be used to produce the urethane(meth)acrylate oligomer.

[0049] (Polyol) Examples of polyols used in producing the urethane (meth)acrylate oligomer include low molecular weight polyols such as aliphatic diols and aromatic diols, and high molecular weight polyols such as polycarbonate polyols. Examples of the aliphatic diol include diols having a linear aliphatic structure, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and 1,16-hexadecanediol; propylene glycol, 1,2 diols having a branched aliphatic structure such as 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, and 1,8-nonanediol; and diols having an alicyclic structure such as cyclopropanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, tricyclodecanediol, and adamantyldiol. These may be used alone or in combination of two or more. Examples of the aromatic diol include bishydroxyethoxybenzene, bishydroxyethyl terephthalate, bisphenol A, and the like. These may be used alone or in combination of two or more. Among the above, it is preferable to use at least one of aliphatic diols and high molecular weight polyols from the viewpoint of increasing the transparency of the active energy ray-cured resin layer.

[0050] The polycarbonate polyol can be obtained, for example, by reacting at least one carbonate compound selected from the group consisting of alkylene carbonate, diaryl carbonate, and dialkyl carbonate with a diol or polyether polyol.

[0051] <Leveling agent> Examples of leveling agents that can be contained in the active energy ray-curable resin composition include silicone-based leveling agents such as silane coupling agents, polyacrylate-based leveling agents, and perfluoroalkyl-based leveling agents. Only one of the leveling agents listed above may be used, or two or more may be used in any combination and ratio. Among these, it is preferable to use silicone macromer-modified acrylate, polyether macromer-modified acrylate, silicone, polyether macromer-modified acrylate, etc. as the leveling agent. When the active energy ray-curable resin composition contains the leveling agent, the surface smoothness of the active energy ray-cured resin layer can be improved.

[0052] The content of the leveling agent contained in the active energy ray-curable resin composition is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the urethane (meth)acrylate. The content of the leveling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the urethane (meth)acrylate.

[0053] <Photopolymerization initiator> The photopolymerization initiator that can be contained in the active energy ray-curable resin composition is not particularly limited as long as it generates radicals by the action of light, and examples thereof include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 1 ... Acetophenones such as 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, and 4-phenylbenzophenone , 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, (4-benzoylbenzyl)trimethylammonium chloride and other benzophenones; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-di Thioxanthones such as chlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; and acylphosphine oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.Among these, it is preferable to use 1-hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and the like. These may be used alone or in combination of two or more.

[0054] The content of the photopolymerization initiator contained in the active energy ray-curable resin composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the urethane (meth)acrylate. The content of the photopolymerization initiator is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the urethane (meth)acrylate.

[0055] <Solvent> Examples of the solvent that can be contained in the active energy ray-curable resin composition include organic solvents such as aromatic solvents, alcohol solvents, ester solvents, ketone solvents, glycol ether solvents, glycol ether ester solvents, chlorine solvents, ether solvents, and amide solvents. Examples of the aromatic solvent include benzene, toluene, and xylene. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, 2-octanone, cyclopentanone, cyclohexanone, and acetylacetone. Examples of the amide solvent include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, 2-pyrrolidone, and N-methylpyrrolidone. Examples of the glycol ether solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono-n-butyl ether, and propylene glycol monomethyl ether acetate. The solvent may be one of the solvents exemplified above, or two or more of them may be used in any combination and ratio.

[0056] The solvent is preferably used so that the solid content concentration of the active energy ray-curable resin composition is 10 to 90 mass %, more preferably 20 to 80 mass %.

[0057] <Epoxy resin layer> The film has an epoxy resin layer, which is obtained by curing an epoxy resin composition containing an epoxy resin (A) and an isocyanate compound (B). That is, the epoxy resin layer contains the epoxy resin (A) and units derived from an isocyanate compound (B). Because the epoxy resin composition contains an isocyanate compound (B) as a crosslinking agent, the time required for curing can be shortened, resulting in increased productivity. Furthermore, because the epoxy resin composition contains an isocyanate compound (B) as a crosslinking agent, a highly transparent epoxy resin layer can be formed. Furthermore, because the epoxy resin layer contains an isocyanate compound-derived unit (B), even when a release film is used as the substrate film, the transfer of release components contained in the release layer constituting the release film can be prevented. This prevents problems such as poor adhesion between the epoxy resin layer and the substrate film.

[0058] (Epoxy resin composition) Each component constituting the epoxy resin composition will be described below.

[0059] 1. Epoxy resin (A) The epoxy resin composition contains an epoxy resin (A). Examples of the epoxy resin (A) include alcohol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol C-type epoxy resins, bisphenol S-type epoxy resins, naphthalene-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, biphenyl-type epoxy resins, triphenylmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, polyfunctional phenol-type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and epoxy resins having any combination of these structures.

[0060] The epoxy resin (A) may be one of the epoxy resins exemplified above, or two or more of them may be used in any combination and ratio.

[0061] Among these, as the epoxy resin (A), it is preferable to use an epoxy resin having at least one skeleton selected from the group consisting of a phenyl skeleton (phenol skeleton), a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, and a dicyclopentadiene skeleton; from the viewpoint of heat resistance, it is more preferable to use an epoxy resin having at least one skeleton selected from the group consisting of a phenyl skeleton, a fluorene skeleton, and a biphenyl skeleton; and from the viewpoints of ease of production and heat resistance, it is even more preferable to use an epoxy resin having at least one skeleton selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, and a biphenyl skeleton.

[0062] The type and skeleton of the epoxy resin (A) can be confirmed by NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscope) analysis, IPC (inductively coupled plasma) optical emission spectroscopy, TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), various types of chromatography, and the like.

[0063] The epoxy resin (A) is preferably the epoxy resin (α) shown below.

[0064] (Epoxy resin (α)) The epoxy resin (α) is preferably a resin obtained by reacting an epoxy compound with a phenolic compound, and can be obtained, for example, by a two-stage method in which a bifunctional epoxy resin is reacted with a divalent hydroxyl group-containing compound. Alternatively, it can be obtained by a one-stage method in which two or more divalent hydroxyl group-containing compounds are directly reacted with epichlorohydrin. However, the two-stage method is preferred because it allows for easier production of a variety of epoxy resins, from low to high molecular weight, than the one-stage method.

[0065] =Epoxy compounds= The epoxy compound is preferably a compound having two or more epoxy groups in the molecule, and examples of such compounds include bifunctional epoxy compounds and polyfunctional epoxy compounds (trifunctional or higher).

[0066] Examples of the bifunctional epoxy compound include bisphenols such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol E diglycidyl ether, bisphenol C diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, bisphenol AD ​​diglycidyl ether, bisphenol acetophenone diglycidyl ether, bisphenol trimethylcyclohexane diglycidyl ether, bisphenol fluorene diglycidyl ether, tetramethyl bisphenol A diglycidyl ether, tetramethyl bisphenol F diglycidyl ether, tetra-t-butyl bisphenol A diglycidyl ether, and tetramethyl bisphenol S diglycidyl ether. biphenol diglycidyl ethers such as biphenol diglycidyl ether, tetramethylbiphenol diglycidyl ether, dimethylbiphenol diglycidyl ether, and tetra-t-butylbiphenol diglycidyl ether; benzenediol diglycidyl ethers such as hydroquinone diglycidyl ether, methylhydroquinone diglycidyl ether, dibutylhydroquinone diglycidyl ether, resorcinol diglycidyl ether, and methylresorcinol diglycidyl ether; dihydroanthrahydroquinone diglycidyl ether, dihydroxydiphenyl ether diglycidyl ether, thiodiphenol diglycidyl ether, and dihydroxynaphthalene diglycidyl ether.

[0067] Further, epoxy compounds in which hydrogen is added to the aromatic ring of the bifunctional epoxy compounds exemplified above; epoxy compounds produced from various carboxylic acids such as adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, biphenyldicarboxylic acid, and dimer acid, and epihalohydrin; epoxy compounds produced from various amine compounds such as diaminodiphenylmethane, aminophenol, and xylenediamine, and epihalohydrin; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethyl ether, and (poly)alkylene glycol diglycidyl ethers consisting only of a chain structure, such as 1,5-pentanediol diglycidyl ether, polypentamethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyhexamethylene glycol diglycidyl ether, 1,7-heptanediol diglycidyl ether, polyheptamethylene glycol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, and 2,2-dimethyl-1,3-propanediol diglycidyl ether; and alkylene glycol diglycidyl ethers having a cyclic structure, such as 1,4-cyclohexanedimethanol diglycidyl ether.

[0068] Examples of the polyfunctional epoxy compound include phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, naphthol novolac epoxy resins, phenol aralkyl epoxy resins, biphenyl aralkyl epoxy resins, dicyclopentadiene epoxy resins, phenol-modified xylene epoxy resins, trisphenolmethane epoxy resins, tetraphenolethane epoxy resins, polyhydric phenol resins obtained by condensation reaction of these various phenols with various aldehydes such as hydroxybenzaldehyde, crotonaldehyde, glyoxal, and epoxy resins using various phenolic compounds such as co-condensation resins of heavy oils or pitches with phenols and formaldehydes.

[0069] The epoxy compound may be used alone or in any combination of two or more of the epoxy compounds listed above in any ratio. Among these, bifunctional epoxy compounds are preferred from the viewpoint of obtaining a copolymer with a molecular weight suitable for film formation while suppressing gelation during the reaction, and bisphenol diglycidyl ethers are more preferred from the viewpoint of the transparency of the epoxy resin layer, and bisphenol A diglycidyl ether is even more preferred from the viewpoint of the transparency and heat resistance of the epoxy resin layer.

[0070] =Phenol compounds= The phenolic compound is preferably a compound having two or more hydroxyl groups bonded to an aromatic ring, and more preferably a compound having two hydroxyl groups bonded to an aromatic ring.

[0071] Examples of the phenolic compounds include bisphenols such as bisphenol A, bisphenol F, bisphenol E, bisphenol C, bisphenol Z, bisphenol S, bisphenol AD, bisphenolacetophenone, bisphenoltrimethylcyclohexane, bisphenolfluorene, tetramethylbisphenol A, tetramethylbisphenol F, tetra-t-butylbisphenol A, and tetramethylbisphenol S; biphenols such as biphenol, tetramethylbiphenol, dimethylbiphenol, and tetra-t-butylbiphenol; benzenediols such as hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcin, and methylresorcin; dihydroanthrahydroquinones such as dihydroanthrahydroquinone; and dihydroxydiphenyl ether. dihydroxynaphthalenes such as dihydroxystilbenes; bisphenol-based novolac resins such as phenol novolac resins, cresol novolac resins, and bisphenol A novolac resins; various phenolic resins such as naphthol novolac resins, phenol aralkyl resins, terpene phenolic resins, dicyclopentadiene phenolic resins, phenol biphenylene resins, and phenol-modified xylene resins; polyhydric phenolic resins obtained by the condensation reaction of these various phenols with various aldehydes such as hydroxybenzaldehyde, crotonaldehyde, and glyoxal; and various phenolic compounds such as co-condensation resins of heavy oils or pitches, phenols, and formaldehydes.

[0072] The phenolic compound may be used alone or in any combination of two or more of the phenolic compounds listed above in any ratio. Among these, bisphenols are preferred from the viewpoints of obtaining a copolymer with a molecular weight suitable for film formation while suppressing gelation during reaction with the glycidyl ether, and from the viewpoints of the transparency and heat resistance of the epoxy resin layer.

[0073] =Amount of epoxy compound and phenolic compound used= When preparing the epoxy resin (α), the amount of the phenolic compound used is preferably 0.05 mol or more, more preferably 0.10 mol or more, even more preferably 0.15 mol or more, and even more preferably 0.20 mol or more, per 1.00 mol of the epoxy compound. On the other hand, the amount of the phenolic compound used is preferably 1.25 mol or less, more preferably 1.20 mol or less, even more preferably 1.15 mol or less, and even more preferably 1.10 mol or less, per 1.00 mol of the epoxy compound. It is preferable from the viewpoint of molecular weight elongation if the amount of the phenolic compound used is equal to or more than the above lower limit. In particular, within this range, the amount of the phenolic compound should be reduced when a low molecular weight epoxy compound is desired, and the amount of the phenolic compound should be increased when a high molecular weight epoxy compound is desired. On the other hand, if the content is equal to or less than the upper limit, an epoxy compound with good curability is easily obtained, which is preferable.

[0074] =Catalyst= In preparing the epoxy resin (α), a catalyst may be used in the reaction between the epoxy compound and the phenolic compound. The catalyst used in producing the epoxy resin (α) is not particularly limited as long as it is a compound with catalytic ability to promote the reaction between the epoxy group and the phenolic hydroxyl group, alcoholic hydroxyl group, or carboxyl group. Examples of the catalyst include alkali metal compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, cyclic amines, and imidazoles.

[0075] Specific examples of the alkali metal compound include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide; alkali metal salts such as sodium carbonate, sodium bicarbonate, sodium chloride, lithium chloride, and potassium chloride; alkali metal alkoxides such as sodium methoxide and sodium ethoxide; alkali metal phenoxides; alkali metal hydrides such as sodium hydride and lithium hydride; and alkali metal salts of organic acids such as sodium acetate and sodium stearate.

[0076] Specific examples of the organic phosphorus compound include tri-n-propylphosphine, tri-n-butylphosphine, triphenylphosphine, tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetramethylphosphonium hydroxide, trimethylcyclohexylphosphonium chloride, trimethylcyclohexylphosphonium bromide, trimethylbenzylphosphonium chloride, trimethylbenzylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, triphenylmethylphosphonium iodide, triphenylethylphosphonium chloride, triphenylethylphosphonium bromide, triphenylethylphosphonium iodide, triphenylbenzylphosphonium chloride, and triphenylbenzylphosphonium bromide.

[0077] Specific examples of tertiary amines include triethylamine, tri-n-propylamine, tri-n-butylamine, triethanolamine, and benzyldimethylamine.

[0078] Specific examples of quaternary ammonium salts include tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, triethylmethylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, benzyltributylammonium chloride, and phenyltrimethylammonium chloride.

[0079] Specific examples of imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenylimidazole.

[0080] Specific examples of cyclic amines include 1,8-diazabicyclo(5,4,0)7-undecene, 1,5-diazabicyclo(4,3,0)5-nonene, and the like. These catalysts may be used alone or in combination of two or more.

[0081] The amount of catalyst used is usually preferably 0.001 to 1% by mass of the reaction solid content. By using the catalyst in an amount equal to or greater than the above-mentioned lower limit, it becomes easier to increase the molecular weight, and by using the catalyst in an amount equal to or less than the above-mentioned upper limit, it becomes easier to suppress gelation. The reaction solid content refers to the total amount of reaction substrates other than the solvent in the reaction system.

[0082] =Solvent= In the preparation of the epoxy resin (α), a solvent may be used in the reaction step of the epoxy compound and the phenolic compound. Examples of the solvent include the organic solvents mentioned above.

[0083] =Reaction conditions= The reaction between the epoxy compound and the phenolic compound may be carried out by a known method. The reaction system may be under normal pressure, elevated pressure or reduced pressure. The reaction temperature is usually 80 to 240°C, preferably 100 to 220°C, and more preferably 120 to 200°C. A reaction temperature equal to or higher than the lower limit is preferred because the reaction proceeds easily. A reaction temperature equal to or lower than the upper limit is preferred because side reactions are less likely to proceed and a high-purity epoxy compound can be obtained. The reaction time is not particularly limited, but is usually 0.5 to 24 hours, preferably 1 to 22 hours, and more preferably 1.5 to 20 hours. A reaction time of not more than the above upper limit is preferred from the viewpoint of improving production efficiency, and a reaction time of not less than the above lower limit is preferred from the viewpoint of reducing unreacted components.

[0084] (Molecular weight of epoxy resin (α)) The mass average molecular weight (mass average molecular weight before curing) of the epoxy resin (α) contained in the epoxy resin composition is preferably 2,000 to 300,000, and more preferably 10,000 to 100,000. When the weight average molecular weight is equal to or greater than the lower limit, an epoxy resin layer having sufficient elasticity and elongation can be obtained, whereas when the weight average molecular weight is equal to or less than the upper limit, a coating liquid suitable for efficient film formation can be obtained without being limited by the type of solvent.

[0085] (epoxy equivalent of epoxy resin (α)) The epoxy equivalent of the epoxy resin (α) is preferably 100 g / eq or more, more preferably 200 g / eq or more, even more preferably 300 g / eq or more, and even more preferably 500 g / eq or more.

[0086] On the other hand, the epoxy equivalent is preferably 200,000 g / eq or less, more preferably 150,000 g / eq or less, even more preferably 100,000 g / eq or less, and even more preferably 50,000 g / eq or less.

[0087] An epoxy equivalent of at least the above lower limit is preferred from the viewpoint of flexibility of the epoxy compound, whereas an epoxy equivalent of at most the above upper limit is preferred from the viewpoint of increasing the density between crosslinking points between epoxy groups and making it easier to obtain cured physical properties when curing an epoxy compound-containing composition described below. In the present invention, the term "epoxy equivalent" is defined as "the mass of an epoxy compound containing one equivalent of an epoxy group" and can be measured in accordance with JIS K7236:2009.

[0088] 2. Isocyanate Compound (B) The epoxy resin composition contains an isocyanate compound (B) as a crosslinking agent, which can increase the curing rate, resulting in improved optical properties, heat resistance, and solvent resistance of the resulting epoxy resin layer. In the present invention, the term "crosslinking agent" refers to a component that contributes to the crosslinking reaction and / or chain extension reaction between epoxy groups in the epoxy resin (A).

[0089] Examples of the isocyanate compound (B) include aliphatic isocyanates such as methylcyclohexane diisocyanate, hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, dimer acid diisocyanate, and trimethylhexamethylene diisocyanate; aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate; and lysine triisocyanate. Further examples include isocyanate compounds (e.g., adducts of isocyanate compounds, biurets of isocyanate compounds, etc.) obtained by reacting the isocyanate compounds exemplified above with compounds having an active hydrogen atom such as an amino group, a hydroxyl group, a carboxyl group, or water, and trimers to pentamers of the isocyanate compounds exemplified above (e.g., isocyanurates of isocyanate compounds, etc.).

[0090] The isocyanate compound (B) may be one of the isocyanate compounds exemplified above, or two or more of them may be used in any combination and ratio. Among these, compounds having an aliphatic isocyanate as the main skeleton are preferred from the viewpoint of film transparency and weather resistance, and compounds having hexamethylene diisocyanate as the main skeleton are more preferred.

[0091] The content of the isocyanate compound (B) is preferably 0.1 to 100 parts by mass, more preferably 1 to 80 parts by mass, and even more preferably 5 to 60 parts by mass, relative to 100 parts by mass of the epoxy resin (A).

[0092] 3. Other ingredients The epoxy resin composition may contain components other than the epoxy resin (A) and the isocyanate compound (B). Examples of the other components include crosslinking agents other than the isocyanate compound (B), leveling agents, solvents, curing accelerators (excluding those corresponding to the crosslinking agents), coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, filler pigments, inorganic fillers, organic fillers, etc. The other components can be used in appropriate combinations depending on the desired physical properties of the epoxy resin composition.

[0093] (Crosslinking agent) Examples of the crosslinking agent other than the isocyanate compound (B) include polyfunctional phenols, amine compounds, acid anhydride compounds, imidazole compounds, amide compounds, cationic polymerization initiators, organic phosphines, etc. Among these, it is preferable to use an imidazole compound as the crosslinking agent other than the isocyanate compound (B), and it is preferable to use the isocyanate compound (B) and an imidazole compound in combination as the crosslinking agent.

[0094] Examples of the polyfunctional phenols include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AD, bisphenol Z, and tetrabromobisphenol A; biphenols such as 4,4'-biphenol and 3,3',5,5'-tetramethyl-4,4'-biphenol; catechol, resorcinol, hydroquinone, and dihydroxynaphthalenes; and compounds in which the hydrogen atoms bonded to the aromatic rings of these compounds have been substituted with non-interfering substituents such as halogen groups, alkyl groups, aryl groups, ether groups, ester groups, and organic substituents containing hetero elements such as sulfur, phosphorus, and silicon. Further examples include the phenols exemplified above, and novolaks and resols which are polycondensates of monofunctional phenols such as phenol, cresol, and alkylphenols with aldehydes.

[0095] Examples of the amine compounds include aliphatic primary, secondary, and tertiary amines, aromatic primary, secondary, and tertiary amines, cyclic amines, guanidines, and urea derivatives. Specific examples include triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, metaxylenediamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, dimethylurea, and guanylurea.

[0096] Examples of the acid anhydride compounds include phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and condensates of maleic anhydride and unsaturated compounds.

[0097] Examples of the imidazole compounds include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and benzimidazole.

[0098] Examples of the amide compounds include dicyandiamide and its derivatives, polyamide resins, and the like.

[0099] The cationic polymerization initiator generates cations when exposed to heat or active energy rays, and examples thereof include aromatic onium salts. Specifically, SbF6 - , BF4 - , AsF6 - , PF6 - , CF3SO3, B(C6F5) 4- and an aromatic cation component containing an atom such as iodine, sulfur, nitrogen, phosphorus, etc. Among these, diaryliodonium salts and triarylsulfonium salts are preferred.

[0100] Examples of the organic phosphines include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Examples of the phosphonium salts include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate. Examples of the tetraphenylboron salts include 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate.

[0101] When polyfunctional phenols, amine compounds, or acid anhydride compounds are used, they are preferably used so that the equivalent ratio of functional groups in the crosslinking agent (hydroxyl groups of polyfunctional phenols, amino groups of amine compounds, or acid anhydride groups of acid anhydride compounds) to all epoxy groups in the epoxy resin composition is in the range of 0.01 to 1.5.

[0102] When an imidazole compound is used, it is preferably used in an amount of 0.001 to 10 parts by mass relative to 100 parts by mass of the total epoxy components.

[0103] When an amide compound is used, it is preferably used in an amount of 0.001 to 20% by mass in 100% by mass of the epoxy resin composition.

[0104] When a cationic polymerization initiator is used, it is preferably used in an amount of 0.001 to 15 parts by mass relative to 100 parts by mass of the total epoxy components.

[0105] When organic phosphines are used, they are preferably used in an amount of 0.001 to 20% by mass in 100% by mass of the epoxy resin composition.

[0106] (Leveling agent) The epoxy resin composition may contain a leveling agent to improve the surface appearance of the film formed therefrom. Adding a leveling agent to the epoxy resin composition also makes it possible to control the water droplet contact angle on the surface of the epoxy resin layer. Examples of leveling agents include silicone-based leveling agents such as silane coupling agents, polyacrylate-based leveling agents, and perfluoroalkyl-based leveling agents. Only one of the leveling agents listed above may be used, or two or more may be used in any combination and ratio. Among these, silicone macromer-modified acrylate, polyether macromer-modified acrylate, silicone, or polyether macromer-modified acrylate is preferred.

[0107] (solvent) The solid content concentration of the epoxy resin composition may be adjusted by adding a solvent to the epoxy resin composition. Examples of the solvent include the organic solvents mentioned above. The solvent is used so that the solid content concentration of the epoxy resin composition is preferably 10 to 90 mass %, more preferably 20 to 80 mass %.

[0108] <Physical properties of the cured product (epoxy resin layer)> The epoxy resin layer of the present film is a cured product obtained by curing the above-mentioned epoxy resin composition. In the present invention, "curing" means intentionally curing an epoxy resin composition by heat and / or light, etc. The degree of curing may be selected depending on the desired physical properties and application, and may be in a completely cured state or a semi-cured state, but completely cured is preferred from the viewpoint that the physical properties of the cured product will not change even if a heat treatment is performed in a subsequent step.

[0109] Whether the epoxy resin layer is completely cured or not can be confirmed by the glass transition temperature measured during heating and reheating using a differential scanning calorimeter in accordance with JIS K7121: 2012. In the present invention, the epoxy resin layer is considered to be completely cured when the glass transition temperature during reheating does not increase by 3°C or more from that during heating.

[0110] The thickness of the epoxy resin layer is preferably from 1 to 1000 μm, more preferably from 5 to 500 μm, and even more preferably from 10 to 300 μm. When the thickness of the epoxy resin layer is within the above range, the layer has suitable handleability and bending resistance, making it suitable for use in electronic components.

[0111] When the thickness of the epoxy resin layer is P and the thickness of the active energy ray-cured resin layer is Q, the value of P / Q is preferably 1 or more, more preferably 5 or more, and even more preferably 10 or more. The value of P / Q is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

[0112] The glass transition temperature of the epoxy resin layer is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 115°C or higher, even more preferably 120°C or higher, and even more preferably 125°C or higher. When the glass transition temperature is within the above range, the heat resistance of the epoxy resin layer is good.

[0113] When the epoxy resin layer is used in electronic components such as displays, it is preferable that the epoxy resin layer has high transparency. From this viewpoint, the light transmittance at 400 nm of the epoxy resin layer is preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and even more preferably 88% or more. The light transmittance of the epoxy resin layer at 650 nm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The light transmittance of the epoxy resin layer is a value measured in accordance with JIS K7375:2008.

[0114] The haze of the epoxy resin layer is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less, as measured in accordance with JIS K 7136:2000.

[0115] The yellowness index (YI) of the epoxy resin layer is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. The yellowness index (YI) of the epoxy resin layer is a value measured in accordance with JIS K7373:2008.

[0116] When the epoxy resin layer is used in electronic components such as flexible displays, it is preferable that the epoxy resin layer has flex resistance. The bending resistance is evaluated by the minimum bending radius R at which no cracks or creases occur when the epoxy resin layer is repeatedly bent, for example, 200,000 times. The radius R of the epoxy resin layer is preferably 3 mm or less, more preferably 2 mm or less, even more preferably 1.5 mm or less, and even more preferably 1 mm or less. When the maximum bending radius R is within the above range, the durability against bending is good when used in electronic components such as flexible displays.

[0117] Furthermore, it is preferable that the water droplet contact angles on both surfaces of the epoxy resin layer are 90 degrees or less. If the water droplet contact angles are within this range, problems such as poor adhesion are unlikely to occur even when a functional layer or wiring is provided in a later process. From this perspective, it is more preferable that the water droplet contact angles on both surfaces of the epoxy resin layer are 85 degrees or less.

[0118] <Functional layer> The film may have a functional layer on at least one surface. Examples of the functional layer include a hard coat layer, an antistatic layer, an antiglare layer, a low reflection layer, an antireflection layer, an antifouling layer, etc. The functional layer may be a single layer having multiple functions, or two or more layers each having a different function may be laminated.

[0119] (Hard coat layer) When the present film has a hard coat layer on at least one surface, scratch resistance, chemical resistance, etc. can be imparted to the surface of the present film. The hard coat layer is preferably formed from a curable resin composition. The curable resin composition is not particularly limited as long as it is cured by irradiation with energy rays such as electron beams, radioactive rays, or ultraviolet rays, or by heating, but from the viewpoints of molding time and productivity, an ultraviolet-curable resin composition is preferred.

[0120] Preferred examples of the curable resin or curable compound constituting the curable resin composition include acrylate compounds, urethane (meth)acrylate compounds, epoxy (meth)acrylate compounds, carboxyl group-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, copolymer-based (meth)acrylates, alicyclic epoxy resins, glycidyl ether epoxy resins, vinyl ether compounds, and oxetane compounds. These curable resins or curable compounds can be used alone or in combination of two or more. In particular, in order to obtain a curable resin that imparts excellent surface hardness, it is preferable that the curable resin composition contains, for example, a radical polymerization type curable compound such as a polyfunctional (meth)acrylate compound, a polyfunctional urethane (meth)acrylate compound, or a polyfunctional epoxy (meth)acrylate compound, and a thermal polymerization type curable compound such as an alkoxysilane or an alkylalkoxysilane.

[0121] Furthermore, the curable resin composition may be an organic-inorganic hybrid curable resin composition obtained by incorporating an inorganic component into the curable resin or curable compound. Examples of the organic-inorganic hybrid curable resin composition include a curable resin composition obtained by incorporating an inorganic component having a reactive functional group into the curable resin or curable compound. By utilizing such an inorganic component having a reactive functional group, for example, the inorganic component can be copolymerized and crosslinked with a radically polymerizable monomer, thereby reducing cure shrinkage and exhibiting high surface hardness compared to organic-inorganic hybrid curable resin compositions in which an inorganic component is simply incorporated into an organic binder. Furthermore, from the perspective of reducing cure shrinkage, it is also preferable to use an organic-inorganic hybrid curable resin composition containing UV-reactive colloidal silica as the inorganic component having a reactive functional group.

[0122] The curable resin composition for forming the hard coat layer may contain, in addition to the curable resin or curable compound, a leveling agent, a photopolymerization initiator, a refractive index adjusting component, a lubricant, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a filler, glass fiber, silica, and the like.

[0123] <<Epoxy film manufacturing method>> The method for producing the epoxy film of the present invention is not particularly limited, and for example, an epoxy film may be obtained by applying a coating liquid comprising the above-mentioned epoxy resin composition to a substrate film, such as a release film, and curing the coating liquid; then applying the above-mentioned active energy ray-curable resin composition to the epoxy resin layer and curing the coating liquid; and peeling the substrate film (release film) from the epoxy resin layer. Alternatively, an epoxy film may be obtained by applying the above-mentioned active energy ray-curable resin composition to a substrate film (release film) and curing the coating liquid; applying the above-mentioned epoxy resin composition to an active energy ray-curable resin cured product layer and curing the coating liquid; and peeling the substrate film (release film) from the active energy ray-curable resin cured product layer. The epoxy film can be used in the state where it is stuck to the base film, that is, in the form of an epoxy film with a base film.

[0124] The coating solution may be applied to the substrate film by a known method, such as comma coating, gravure coating, reverse coating, knife coating, dip coating, spray coating, air knife coating, spin coating, roll coating, printing, slide coating, curtain coating, die coating, casting, bar coating, or extrusion coating.

[0125] The curing conditions for the coating liquid may be adjusted as appropriate depending on the components and blending amounts in the epoxy resin composition or the active energy ray-curable resin composition, but the curing conditions for the epoxy resin composition are preferably heating conditions of 1 to 180 minutes at 80 to 200°C. Furthermore, when heating the epoxy resin composition, it is preferable to perform heating in a two-stage process, including primary heating at 80 to 160°C for 1 to 30 minutes and secondary heating at 120 to 200°C, which is 40 to 120°C higher than the primary heating temperature, for 1 to 150 minutes, in order to reduce curing defects.

[0126] When curing the active energy ray-curable resin composition, it is preferable to remove the solvent and then irradiate it with active energy rays to cure it. Methods for removing the solvent include, for example, natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations of these. Of these, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, and even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes.

[0127] The active energy rays to be irradiated are appropriately selected depending on the type of active energy ray-curable resin (particularly the type of photopolymerizable functional group possessed by the active energy ray-curable resin), and the type and amount of the photopolymerization initiator, if any. Specific examples include one or more types of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization devices widely used in this field can be used. It is preferable to select the type of active energy ray-curable resin so that it can be photopolymerized by ultraviolet light.

[0128] Examples of the light source for the actinic energy rays include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source emitting light in a wavelength range of 380 to 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp. The UV irradiation intensity is usually 10 to 3,000 mW / cm 2 The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute.

[0129] <Base film> The substrate film may be, for example, a thin sheet-like substrate made of paper, resin, metal or the like, on the surface of which a release layer is formed by applying a silicone resin release agent or the like. The substrate is preferably paper or resin from the viewpoints of low cost, ease of processing, and ease of disposal and recycling, and more preferably resin from the viewpoint of transparency.

[0130] Examples of the paper include fine paper, kraft paper, glassine paper, parchment paper, and supercalendered kraft paper whose surfaces have been silicone coated.

[0131] As the resin film, for example, a film containing as a main component polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyimide, or polycarbonate can be used. Among the above, it is preferable to use a resin film containing polyester as a main component in terms of appearance, ease of processing, durability, heat resistance, cost, etc. The resin film may have a single layer structure or a multi-layer structure of two or more layers.

[0132] The term "main component resin" refers to the resin with the highest content among the resins constituting the base material, specifically a resin that accounts for 50% by mass or more, particularly 70% by mass or more, particularly 80% by mass or more, and particularly 90% by mass or more (including 100% by mass) of that.

[0133] The polyester is preferably one obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. The polyester may be a polyester composed of one type of aromatic dicarboxylic acid and one type of aliphatic glycol, or a copolymer polyester in which one or more other components are further copolymerized. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. On the other hand, examples of dicarboxylic acids used as other components of the copolymer polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and sebacic acid, and examples of glycol components include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol. Further, oxycarboxylic acids such as p-oxybenzoic acid can also be used.

[0134] Typical examples of polyesters include polyethylene terephthalate obtained by polycondensation of terephthalic acid and ethylene glycol, and polyethylene naphthalate obtained by polycondensation of 2,6-naphthalenedicarboxylic acid and ethylene glycol. The polyester film may be either a non-stretched film or a stretched film, but from the viewpoint of mechanical strength, a stretched film is preferred, and a biaxially stretched film is more preferred. The polyester film may be previously subjected to a surface treatment such as a corona treatment or a plasma treatment.

[0135] The base film is preferably a release film further including a release layer as the outermost layer on the side in contact with the epoxy resin layer. The inclusion of the release layer improves the releasability between the epoxy resin layer and the release film.

[0136] The components of the release layer are not particularly limited, and may contain silicone compounds, fluorine compounds, waxes, surfactants, etc. From the viewpoint of a good balance between cost and releasability, it is preferable to use silicone compounds. Furthermore, a release control agent may be used in combination to adjust the release properties of the release layer. The release layer may be laminated directly onto the substrate, or may be laminated via another layer, such as an easy-adhesion layer or an antistatic layer.

[0137] (Base film thickness) The thickness of the base film is preferably 5 to 300 μm, more preferably 20 to 150 μm. When the thickness of the base film is equal to or greater than the lower limit, handling properties are improved when applying the epoxy resin composition or peeling the epoxy resin layer from the base film, which is preferable. In addition, if the thickness is equal to or less than the upper limit, the base film is less likely to break, and material costs can be reduced, which is also preferable.

[0138] When the substrate film has a release layer, the thickness of the release layer after curing is preferably 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. When the thickness of the release layer is equal to or greater than the lower limit, the release properties are good and the handling properties when peeling off the epoxy resin layer are improved, so that a film with good appearance can be obtained, which is preferable. Furthermore, when the thickness is equal to or less than the upper limit, there is no problem with the releasability, and the cost of the release layer can be reduced, which is preferable.

[0139] <Protective film> The film may have a protective film to prevent damage or deformation of the epoxy resin layer. That is, the present invention may be an epoxy film with a protective film. The configuration of the epoxy film with a protective film is not particularly limited, and examples thereof include a configuration of protective film / functional layer / epoxy resin layer / active energy ray-cured resin layer / substrate film. The protective film may consist of a single layer of substrate (protective film substrate), or may have a structure that further includes an adhesive layer as the outermost layer on the side that comes into contact with the epoxy resin layer in addition to the protective film substrate.

[0140] The protective film substrate is preferably a resin film, more specifically, a film mainly composed of a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate or polyethylene naphthalate, a polyimide, or a polycarbonate. The specific configuration of the resin film may be the same as that described for the substrate film above. When the protective film substrate is used as a single layer, a film having self-adhesive properties is preferred.

[0141] The constituent components of the adhesive layer are not particularly limited, but examples thereof include rubber-based adhesives, acrylic-based adhesives, polyvinyl ether-based adhesives, urethane-based adhesives, silicone-based adhesives, etc. More specific examples thereof include acrylic resins, urethane-based resins, ethylene-vinyl acetate copolymer resins, polyolefin-based resins, etc.

[0142] <<Wound body>> The epoxy film or the epoxy film with a substrate film of the present invention may be wound around a core and taken up into a roll to form a wound body. The length of the epoxy film or the epoxy film with a substrate film of the present invention is not particularly limited, but from the viewpoint of handleability, it is preferably 5 m or more, more preferably 10 m or more, and even more preferably 50 m or more. The length of the epoxy film or the epoxy film with a substrate film of the present invention is preferably 10,000 m or less.

[0143] The core refers to a cylindrical core used for winding up the film. The material of the core is not particularly limited, but examples thereof include paper, resin-impregnated paper, acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenolic resin, and inorganic-containing resin. Among these, from the viewpoints of a small coefficient of thermal expansion, high rigidity, low swelling due to humidity, and excellent winding properties, it is preferable to use a resin such as acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenolic resin, or inorganic-containing resin. When the core material is paper, the desired properties can be easily obtained by coating the surface with a resin, etc. Furthermore, from the viewpoint of surface smoothness, it is also preferable that the core be a tube made of resin-impregnated paper.

[0144] When constructing a wound body, it is preferable to wind the epoxy film or the epoxy film with a base film around a core so that the epoxy resin layer of the epoxy film or the epoxy film with a base film is on the inside and the active energy ray-cured resin layer is on the outside.

[0145] <<Application>> The film has a low water droplet contact angle on both surfaces of the epoxy resin layer and good adhesion to functional layers and wiring, making it suitable for use in electronic components such as displays and printed wiring boards. [Example]

[0146] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below.

[0147] <<Materials>> The materials used in the examples and comparative examples are as follows.

[0148] <Epoxy resin> (A-1): An epoxy resin containing bisphenol A type epoxy resin as the main component ("YL7852BT40" manufactured by Mitsubishi Chemical Corporation) was used.

[0149] <Crosslinking agent> (B-1): A polyisocyanate containing hexamethylene diisocyanate as a main component ("Coronate 2715" manufactured by Tosoh Corporation) was used. (B-2): A polyisocyanate containing hexamethylene diisocyanate as the main component ("Takenate D-160N" manufactured by Mitsui Chemicals, Inc.) was used. (B-3): 1-benzyl-2-phenylimidazole ("Curezol 1B2PZ" manufactured by Shikoku Chemical Industries, Ltd.) was used.

[0150] <Additives> (C-1): A leveling agent (BYK-3566 manufactured by BYK Japan Co., Ltd., silicone and polyether macromer modified acrylate) was used.

[0151] <Solvent> (D-1): Toluene (D-2): Methyl ethyl ketone

[0152] <Urethane (meth)acrylate oligomer> (E-1): "Shiko (registered trademark) UT-5670" manufactured by Mitsubishi Chemical Corporation was used.

[0153] <Photopolymerization initiator> (F-1): "Omnirad184" manufactured by IGM Resins BV was used.

[0154] <<Base film>> (G-1): A release layer composition was applied to one side of a polyethylene terephthalate film (Diafoil (registered trademark), manufactured by Mitsubishi Chemical Corporation, thickness 125 μm) using a gravure roll so that the thickness after drying would be 0.5 μm, and the film was dried at 150°C for 20 seconds to remove the solvent, resulting in a base film (release film). The release layer composition was obtained by uniformly mixing 100 parts by mass of melamine resin paint (manufactured by Miwa Laboratory Co., Ltd., "RP-30-30"), 10 parts by mass of curing agent (manufactured by Miwa Laboratory Co., Ltd., "CP-CATALYST"), and 100 parts by mass of ethyl acetate. (G-2): A substrate film (manufactured by Mitsui Chemicals Tohcello Inc., SP-PET (registered trademark) O3-BU, thickness (100 μm)) consisting of a polyester film and a silicone-based release layer was used.

[0155] <<Preparation of epoxy film>> [Example 1] A coating liquid for forming an active energy ray-cured resin layer was obtained by mixing urethane (meth)acrylate oligomer (E-1), photopolymerization initiator (F-1), additive (C-1), solvents (D-1) and (D-2) in the proportions shown in Table 1. The coating liquid for forming an active energy ray-cured resin layer was applied to the release layer of the substrate film (G-1) obtained above using a gravure roll so that the thickness after drying would be 3 μm, and the coating liquid was dried at 80° C. for 2 minutes to remove the solvent. Thereafter, the coating liquid was applied to the release layer of the substrate film (G-1) using a gravure roll so that the thickness after drying would be 3 μm, and the coating liquid was dried at 80° C. for 2 minutes to remove the solvent. After that, the coating liquid was applied to the release layer of the substrate film (G-1) using a gravure roll so that the thickness after drying would be 3 μm. 2 Thus, a laminated film (base sheet) having an active energy ray-cured resin layer laminated thereon was obtained. Next, epoxy resin (A-1), crosslinking agents (B-1) and (B-2), additive (C-1), and solvents (D-1) and (D-2) were mixed in the proportions shown in Table 1 to obtain a coating liquid for forming an epoxy resin layer. The coating liquid for forming an epoxy resin layer was applied to the active energy ray-cured resin layer of the laminate film obtained above using an applicator, and curing treatment was performed using a constant temperature dryer by primary heating at 80°C for 2 minutes and secondary heating at 180°C for 5 minutes, followed by natural cooling to room temperature (25°C) to form an epoxy resin layer. In this way, the epoxy film with a base film of Example 1 was obtained. Furthermore, a wound body was produced by winding the epoxy film with a base film of Example 1 around a core (made of ABS resin) with the epoxy resin layer facing inward. The thickness of the epoxy resin layer of the obtained epoxy film with a substrate film was 35 μm. The substrate film was peeled off from the obtained epoxy film with a substrate film, and the glass transition temperature of the epoxy resin layer was measured. The glass transition temperature of the epoxy resin layer was 129°C, and the glass transition temperature upon re-heating was also 129°C, confirming that the epoxy resin layer was completely cured.

[0156] [Example 2] An epoxy film with a base film and a wound body were produced in the same manner as in Example 1, except that the composition of the coating liquid for forming an epoxy resin layer was changed as shown in Table 1. The thickness of the epoxy resin layer of the obtained epoxy film with a base film was 35 μm. The substrate film was then peeled off from the resulting epoxy film with the substrate film attached, and the glass transition temperature of the epoxy resin layer was measured. The glass transition temperature of the epoxy resin layer was 112°C, and the glass transition temperature upon reheating was 110°C, confirming that the epoxy resin layer was completely cured.

[0157] [Comparative Example 1] An epoxy film with a substrate film and a wound body were prepared in the same manner as in Example 1, except that an active energy ray-cured resin layer was not provided. The thickness of the epoxy resin layer of the obtained epoxy film with a substrate film was 35 μm. The substrate film was peeled from the obtained epoxy film with a substrate film, and the glass transition temperature of the epoxy resin layer was measured. The glass transition temperature was 128°C, and the glass transition temperature upon reheating was 129°C, confirming that the epoxy resin layer was completely cured.

[0158] Comparative Example 2 An epoxy film with a substrate film and a wound body were produced in the same manner as in Example 1, except that a substrate film (G-2) consisting of a polyester film and a silicone-based release layer was used and no active energy ray-cured resin layer was provided. The thickness of the epoxy resin layer of the obtained epoxy film with a substrate film was 35 μm. The substrate film was also peeled from the obtained epoxy film with a substrate film, and the glass transition temperature of the epoxy resin layer was measured. The glass transition temperature was 128°C, and the glass transition temperature upon reheating was 129°C, confirming complete curing.

[0159] <Evaluation items> (1) Glass transition temperature and degree of hardening The glass transition temperature and degree of cure of the epoxy resin layer were measured based on the "midpoint glass transition temperature (Tmg)" described in JIS K7121:2012 "Method for measuring transition temperature of plastics." Specifically, a differential scanning calorimeter "DSC8500" manufactured by PerkinElmer Japan Co., Ltd. was used to measure the glass transition temperature and degree of cure. The glass transition temperature was increased from 20 to 250°C at a rate of 10°C / min, then decreased to 0°C at a rate of 10°C / min, and then increased again from 0 to 250°C at a rate of 10°C / min. The glass transition temperature was considered to be fully cured when the glass transition temperature upon re-heating did not rise by more than 3°C from the glass transition temperature upon heating.

[0160] (2) Haze The haze of the epoxy films obtained by peeling off the substrate film from the epoxy films with substrate film of each of the examples and comparative examples was measured in the range of 400 nm to 650 nm using a haze meter "NDH 7000II" manufactured by Nippon Denshoku Industries Co., Ltd. The measurement was carried out in accordance with JIS (haze: JIS K 7136:2000).

[0161] (3) Heat resistance test The epoxy film obtained by peeling off the base film from each of the epoxy films with base film of each of the Examples and Comparative Examples was cut into a piece of 5 cm x 5 cm and placed on a metal container. The metal container with the epoxy film placed on it was placed in an oven heated to 120°C and left to stand for 5 minutes. The container was then removed from the oven and allowed to cool naturally to room temperature. After cooling, the film was checked for curling to evaluate its heat resistance. A: No curling occurs. B: Curling occurs.

[0162] (4) Flexibility (R) Using a bending tester (Yuasa System Co., Ltd., DLDMLH-FS), the epoxy films of the examples and comparative examples were subjected to a bending test 200,000 times, and the minimum bending radius R at which cracks and creases did not occur was evaluated. In addition, the epoxy films of Example 1 and Comparative Example 1 did not develop cracks or creases even when R=1 mm, and therefore in Table 1 they are indicated as "≦1".

[0163] (5) Coating thickness The thickness of the epoxy resin layer was measured using a thickness gauge (manufactured by Mitutoyo Corporation, trade name "ABS Digimatic Indicator ID-F125").

[0164] (6) Water droplet contact angle The substrate film was removed from the epoxy film with the substrate film attached, and the water droplet contact angle of the epoxy film was measured using a contact angle meter "DropMaster500" manufactured by Kyowa Interface Science Co., Ltd. Ion-exchanged water was used for the measurement. The measurement temperature was 25°C, and the amount of ion-exchanged water dropped was 2 μL. The water droplet contact angle was evaluated one second after the droplet landed. Measurements were taken at three points on each side of the epoxy film, and the average was calculated. In Table 1, the surface not in contact with the substrate film (epoxy resin layer surface) is referred to as the "front surface" of the epoxy film, and the surface in contact with the substrate film (active energy ray-cured resin layer surface) is referred to as the "back surface" of the epoxy film.

[0165] [Table 1]

[0166] The epoxy films having the active energy ray-cured resin layer of the examples were highly transparent, and no curling was observed even when subjected to a heat resistance test at a temperature below the glass transition point. The epoxy films of the examples also had excellent flex resistance. On the other hand, in the epoxy film of the comparative example, curling occurred with the air-facing side of the epoxy resin convex in the heat resistance test under the same conditions. [Explanation of symbols]

[0167] 1. Base film 2. Active energy ray cured resin layer 3 Epoxy resin layer 5 Epoxy film 10 Epoxy film with base film

Claims

1. an epoxy resin layer and an active energy ray-cured resin layer are laminated in this order in contact with each other; the epoxy resin layer comprises a cured product of an epoxy resin composition containing an epoxy resin (A) and an isocyanate compound (B); The active energy ray-cured resin layer of the epoxy film contains a urethane (meth)acrylate structural unit.

2. 2. The epoxy film according to claim 1, wherein the thickness of the epoxy resin layer is 1 to 1000 μm, and the thickness of the active energy ray-cured resin layer is 0.5 to 20 μm.

3. 3. The epoxy film according to claim 1, wherein P / Q is 1 to 100, where P is the thickness of the epoxy resin layer and Q is the thickness of the active energy ray-cured resin layer.

4. The epoxy film according to any one of claims 1 to 3, wherein the epoxy resin (A) is a resin obtained by reacting an epoxy compound with a phenolic compound.

5. 5. The epoxy film according to claim 4, wherein the epoxy compound is a compound having two or more epoxy groups in the molecule.

6. 6. The epoxy film according to claim 4, wherein the phenolic compound is a compound having two or more hydroxyl groups bonded to an aromatic ring.

7. The epoxy film according to any one of claims 1 to 6, wherein the isocyanate compound (B) is a compound having an aliphatic isocyanate as a main skeleton.

8. The epoxy film according to any one of claims 1 to 7, wherein the epoxy resin layer further contains a leveling agent.

9. The epoxy film according to any one of claims 1 to 8, wherein the glass transition temperature of the epoxy resin layer is 100°C or higher.

10. The epoxy film according to any one of claims 1 to 9, further comprising a functional layer on at least one surface thereof.

11. An epoxy film according to any one of claims 1 to 10 and a base film, An epoxy film with a base film, comprising the base film and the epoxy resin layer laminated thereon via the active energy ray-cured resin layer.

12. A wound body obtained by winding the epoxy film according to any one of claims 1 to 10 or the epoxy film with a base film according to claim 11 around a core.

13. a step of curing an active energy ray-curable resin composition containing a urethane (meth)acrylate oligomer to form an active energy ray-cured resin layer; and applying an epoxy resin composition containing an epoxy resin (A) and an isocyanate compound (B) onto the active energy ray-cured resin layer and curing the composition to form an epoxy resin layer.

14. The method for producing an epoxy film according to claim 13, wherein the mass average molecular weight of the epoxy resin (A) is 2,000 to 300,000.

15. The method for producing an epoxy film according to claim 13 or 14, wherein the isocyanate compound (B) is a compound having an aliphatic isocyanate as a main skeleton.

16. The method for producing an epoxy film according to any one of claims 13 to 15, wherein the epoxy resin composition further contains a leveling agent.

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