JP2023145889A - Epoxy film, epoxy film with substrate film, method for producing epoxy film, and application thereof - Google Patents

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

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.

Epoxy resins have excellent heat resistance, adhesiveness, water resistance, mechanical strength, electrical properties, etc., and are therefore used in various fields such as paints, civil engineering, adhesives, and electronic components.

For example, Patent Document 1 discloses a curable resin composition using a specific polymeric polyether polyol resin, a trifunctional or higher functional epoxy resin, and an epoxy resin curing agent, and a cured product obtained by curing the composition. It is described that it is applicable to foldable OLED displays because it has excellent heat resistance and bending resistance.

International Publication No. 2020/080292

However, when forming a cured product from the curable resin composition described in Patent Document 1, the curing time is as long as 1 hour, and due to the effect of curing at high temperature for a long time, the components of the release layer may be transferred to the epoxy layer. , it was found that transparency may be compromised.

Furthermore, when a film made of epoxy resin is used for electronic components or the like, a functional layer such as a hard coat layer or wiring may be provided on the film in a post-process. Therefore, the surface of the film is required to have good wettability with respect to the functional layer and wiring.
However, when a film is formed by applying a coating liquid of an epoxy resin composition to a base film, the longer the time required for curing the epoxy resin composition, the more the release component of the base film is transferred to the epoxy resin layer. It has been found that as a result, the water droplet contact angle on the surface of the base film becomes high, which may cause problems such as poor adhesion in subsequent steps.

Therefore, the present inventor attempted to use an isocyanate compound in order to enable the epoxy resin to be cured in a short time.
However, an epoxy resin film obtained by heating and curing an epoxy resin and an isocyanate compound has a problem in that curling occurs when a heating test is performed at a temperature below the glass transition point.

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

In light of the above, an object of the present invention is to obtain an epoxy film that has high transparency and suppresses curling.

In order to solve the above problem, the present inventor conducted further studies and found that since isocyanate can react with moisture in the air, the surface side that comes into contact with air (the side that is not adjacent to the base material) during solvent drying. A difference occurs between the crosslinking density and the crosslinking density on the side that contacts the base material (the side adjacent to the base material). More specifically, the crosslinking density on the side that is not adjacent to the base material becomes lower, resulting in hardening of both surfaces. It was discovered that the difference in degree causes a difference in stress, which causes curling.

Furthermore, the present inventor has proposed that by providing an active energy ray resin cured product layer formed from an active energy ray curable resin composition as a layer that alleviates the shrinkage stress generated by the above mechanism during curing of the epoxy resin layer. It has been found that the above-mentioned problem of curling can be solved.

That is, the present invention has the following aspects.

[1] The first aspect of the present invention includes an epoxy resin layer and an active energy ray resin cured product layer, the epoxy resin layer containing an epoxy resin (A) and an isocyanate compound-derived unit (B), and the above-mentioned The active energy ray resin cured product layer is an epoxy film containing a urethane (meth)acrylate structural unit.

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

[3] In the third aspect of the present invention, in the first or second aspect, when the thickness of the epoxy resin layer is P and the thickness of the active energy ray resin cured product layer is Q, P/ Q is 1 to 100, and is an epoxy film.

[4] A fourth aspect of the present invention is that in any one of the first to third aspects, the epoxy resin (A) is a resin obtained by reacting an epoxy compound and a phenol compound. It is an epoxy film.

[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.

[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.

[7] In a seventh aspect of the present invention, in any one of the first to sixth aspects, the isocyanate compound-derived unit (B) is a compound-derived unit having an aliphatic isocyanate as a main skeleton. , an epoxy film.

[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.

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

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

[11] An eleventh aspect of the present invention comprises the epoxy film of any one of the first to tenth aspects and a base film, and the active energy ray resin cured product layer is applied to the base film. This is an epoxy film with a base film having a structure in which epoxy resin layers are laminated.

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

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

[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.

[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 its main skeleton.

[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.

[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), wherein the base sheet is made of urethane (meth). This is a base sheet containing a cured active energy ray resin layer containing acrylate structural units.

According to the present invention, it is possible to obtain an epoxy film that has high transparency and suppresses curling.

FIG. 1 is a schematic cross-sectional view of an epoxy film with a base film of the present invention.

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

<<Epoxy film>>
The epoxy film of the present invention (hereinafter also referred to as "this film") has an epoxy resin layer and an active energy ray resin cured product layer. In this film, it is preferable that the cured active energy ray resin layer and the epoxy resin layer are directly laminated. The present film preferably has an epoxy resin layer formed on a cured active energy ray resin layer.

The epoxy resin layer of this film contains an isocyanate compound in order to be able to cure in a short time and to increase the transparency of the film. However, since isocyanate can react with moisture in the air, the crosslinking density on the side that comes into contact with the air (the side that is not adjacent to the substrate) and the side that comes into contact with the substrate (the side that is not adjacent to the substrate) during solvent drying was determined by the inventor. A difference occurs in the crosslink density on the side (adjacent surface side), and more specifically, the crosslink density on the side non-adjacent to the base material becomes lower, and the difference in the degree of hardening on both surfaces becomes a difference in stress, which causes curling. I found out that it occurs. Therefore, as a result of extensive studies, the inventor of the present invention found that by further providing an active energy ray resin cured material layer in this film, the strong active energy ray resin cured material layer absorbs the shrinkage stress during curing of the epoxy resin. It has been found that the occurrence of curls can be suppressed. As a result, this film has high transparency and curl resistance.

The present invention also provides an epoxy film with a base film having the above epoxy film and a base film, the base film having a structure in which an epoxy resin layer is laminated on the base film via an active energy ray resin cured product layer. It may also be related to an epoxy film with a material film. As shown in FIG. 1, the epoxy film 10 with a base film includes an epoxy film 5 having an active energy ray resin cured material layer 2 and an epoxy resin layer 3, and a base film 1. The film 10 is formed by laminating a base film 1, an active energy ray resin cured material layer 2, and an epoxy resin layer 3 in this order. In an epoxy film with a base film, when forming the epoxy film, by having an active energy ray resin cured material layer between the thermoplastic base film and the thermosetting epoxy resin layer, the epoxy resin layer is It is thought that the stress caused by the difference in linear expansion between the base film and the epoxy resin layer that occurs during the thermosetting process is reduced, and as a result, the occurrence of curling due to heating is more effectively suppressed.

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. That is, it is preferable that the active energy ray resin cured product layer is 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 interacts with the isocyanate present in the epoxy resin layer, thereby reducing the difference in crosslink density that causes curling as described above. It is presumed that this mechanism can effectively suppress the occurrence of curling in the film.

In addition, in this specification, "(meth)acrylate" has a meaning including "acrylate" and "methacrylate," respectively.
Furthermore, the term "(meth)acryloyl group" includes a "methacryloyl group" and an "acryloyl group," respectively.
Furthermore, "(co)polymer" is meant to include "polymer" and "copolymer" respectively.

<Active energy ray resin cured material layer>
The active energy ray cured resin layer (hereinafter also referred to as "cured material layer") is a layer containing urethane (meth)acrylate structural units, and is a layer obtained by curing an active energy ray curable resin composition. It is.
The active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron beams, and electron beams, ultraviolet rays, and visible light, of which ultraviolet rays are preferred.

In addition to the urethane (meth)acrylate structural units, this cured product layer may contain units derived from isocyanate compounds, leveling agents, photopolymerization initiators, or units derived from photopolymerization initiators. As the isocyanate compound, leveling agent, and photopolymerization initiator, the compounds described below can be appropriately selected.

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. Further, the thickness of the cured material layer is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

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

<Active energy ray curable resin composition>
The active energy ray-curable resin composition for forming this cured product layer contains, for example, a (co)polymer having a (meth)acryloyl group or an oligomer having a (meth)acryloyl group, and in addition to these, one It may contain monomers having the above (meth)acryloyl groups. The active energy ray-curable resin composition may be obtained by further blending other components such as a leveling agent, a photopolymerization initiator, and a solvent as necessary.

Examples of the above-mentioned oligomers having a (meth)acryloyl group include urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, acrylic (meth)acrylate oligomers, polyester (meth)acrylate oligomers, and polycarbonate (meth)acrylates. Examples thereof include polybutadiene (meth)acrylate oligomers, polyether (meth)acrylates, and the like.
In addition, these may be used alone or in combination of two or more types.

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

<Urethane (meth)acrylate oligomer>
As the urethane (meth)acrylate oligomer, those manufactured by known methods using isocyanate compounds, hydroxyl group-containing (meth)acrylates, polyols, etc. can be used.

(Isocyanate compound)
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 above isocyanate compounds may be used alone or in combination of two or more.
Examples of the isocyanate compounds include chain aliphatic polyisocyanates, aromatic polyisocyanates, alicyclic polyisocyanates, and the like.
In addition, these may be used alone or in combination of two or more types.
Among them, from the viewpoint of increasing the bending resistance and hardness of the active energy ray resin cured product layer, at least one of chain aliphatic polyisocyanates and alicyclic polyisocyanates is used in the production of urethane (meth)acrylate oligomers. It is preferable to use

(Hydroxy group-containing (meth)acrylate)
Examples of the hydroxyl group-containing (meth)acrylate used in the production of 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, addition reaction product of 2-hydroxyethyl (meth)acrylate and caprolactone, addition reaction product of 4-hydroxybutyl (meth)acrylate and caprolactone, bisphenol A diglycidyl ether diacrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate glycol mono(meth)acrylate, glycerin (meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate ) acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and the like.

In addition to the above, examples of hydroxyl-containing (meth)acrylates used in the production of the urethane (meth)acrylate oligomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Alkylene having 2 or more and 4 or less carbon atoms between the (meth)acryloyl group and the hydroxyl group, such as meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, etc. A compound having a (meth)acryloyl group and a carboxyl group is reacted with an epoxy compound selected from epoxy compounds having a chain aliphatic structure, a cycloaliphatic structure, or an aromatic structure such as hydroxyalkyl (meth)acrylate having a group. Examples include the obtained epoxy (meth)acrylate.
In addition, these may be used alone or in combination of two or more types. Among them, from the viewpoint of improving the adhesion and solvent resistance of the active energy ray resin cured product layer, trimethylolpropane di(meth)acrylate and trimethylolethane di(meth)acrylate are used in the production of urethane (meth)acrylate oligomers. , pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate.

(polyol)
Examples of the polyol used in the production of 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 diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Straight chain fatty acids such as octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol Diols having a group structure; propylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,2-pentane Diols, diols with branched aliphatic structures such as 3-methyl-1,5-pentanediol, 1,8-nonanediol; cyclopropanediol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, tricyclodecane Examples include diols having an alicyclic structure such as diols and adamantyl diols.
In addition, these may be used alone or in combination of two or more types.
Examples of the aromatic diol include bishydroxyethoxybenzene, bishydroxyethyl terephthalate, bisphenol A, and the like.
In addition, these may be used alone or in combination of two or more types.
Among the above, from the viewpoint of increasing the transparency of the active energy ray resin cured product layer, it is preferable to use at least one of aliphatic diols and high molecular weight polyols.

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.

<Leveling agent>
Examples of the leveling agent that may be included 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. As the leveling agent, only one of the above-mentioned leveling agents may be used, or two or more thereof may be used in combination in any combination and ratio. Among them, 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 above-mentioned leveling agent, the surface smoothness of the active energy ray resin cured product layer can be improved.

The content of the leveling agent contained in the active energy ray-curable resin composition is preferably 0.01 parts by mass or more, and 0.05 parts by mass or more based on 100 parts by mass of urethane (meth)acrylate. It is more preferable that the amount is at least 0.1 part by mass, and even more preferably 0.1 part by mass or more. Further, the content of the leveling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and preferably 10 parts by mass or less with respect to 100 parts by mass of urethane (meth)acrylate. More preferred.

<Photopolymerization initiator>
The photopolymerization initiator that may be included in the active energy ray-curable resin composition is not particularly limited as long as it generates radicals by the action of light, such as diethoxyacetophenone, 2-hydroxy-2-methyl- 1-phenylpropan-1-one, benzyldimethyl 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-propan-1-one, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2 - Acetophenones such as dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoin, benzoin methyl ether, benzoin Benzoins such as ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether; benzophenone, methyl o-benzoylbenzoate, 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]benzenemeth Benzophenones such as naminium bromide, (4-benzoylbenzyl)trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone , 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthon-9-one thioxanthone such as mesochloride; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis( Acyl phosphone oxides such as 2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and the like. Among them, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one It is preferable to use the following.
In addition, these may be used alone or in combination of two or more types.

The content of the photopolymerization initiator contained in the active energy ray-curable resin composition is preferably 0.1 parts by mass or more, and 0.5 parts by mass based on 100 parts by mass of urethane (meth)acrylate. The amount is more preferably at least 1 part by mass, and even more preferably at least 1 part by mass. Further, the content of the photopolymerization initiator is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and 10 parts by mass or less with respect to 100 parts by mass of urethane (meth)acrylate. It is even more preferable.

<Solvent>
Examples of solvents that can be contained in the active energy ray-curable resin composition include aromatic solvents, alcohol solvents, ester solvents, ketone solvents, glycol ether solvents, glycol ether ester solvents, chlorine solvents, Examples include organic solvents such as ether solvents and amide solvents.
Examples of the aromatic solvent include benzene, toluene, xylene, and the like.
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 solvents 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, and diethylene glycol monoethyl ether. -n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono-n-butyl ether, propylene glycol monomethyl ether acetate and the like.
In addition, as the above-mentioned solvent, only one type of the solvents exemplified above may be used, or two or more types may be used in combination in any combination and ratio.

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

<Epoxy resin layer>
This film has an epoxy resin layer, and the epoxy resin layer 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 an epoxy resin (A) and an isocyanate compound-derived unit (B).
Since the epoxy resin composition contains the isocyanate compound (B) as a crosslinking agent, the time required for curing can be shortened, and as a result, productivity can be increased. Moreover, since the epoxy resin composition contains the isocyanate compound (B) as a crosslinking agent, a highly transparent epoxy resin layer can be formed. Furthermore, since the epoxy resin layer contains the unit (B) derived from an isocyanate compound, even if a release film is used as the base film, the release layer contained in the release film constitutes the release film. Transfer of components can be prevented. This prevents problems such as poor adhesion between the epoxy resin layer and the base film.

(Epoxy resin composition)
Each component constituting the epoxy resin composition will be explained below.

1. Epoxy resin (A)
The epoxy resin composition contains an epoxy resin (A). Examples of the epoxy resin (A) include alcohol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol C type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, Cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, polyfunctional phenol type epoxy resin , aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and epoxy resins in which these structures are arbitrarily combined.

As the epoxy resin (A), only one type of the epoxy resins exemplified above may be used, or two or more types may be used in combination in any combination and ratio.

Among these, the epoxy resin (A) is at least 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. It is preferable to use an epoxy resin having one or more skeletons, and from the viewpoint of heat resistance, it is more preferable to use an epoxy resin having at least one selected from the group consisting of a phenyl skeleton, a fluorene skeleton, and a biphenyl skeleton. From the viewpoint of ease of production and heat resistance, it is more preferable to use an epoxy resin having at least one skeleton selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, and biphenyl skeleton.

The type and skeleton of the epoxy resin (A) are determined by NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscopy) analysis, and IPC (high frequency inductively coupled plasma) emission spectrometry. It can be confirmed by methods such as TGA (thermal mass spectrometry), DSC (differential scanning calorimetry), and various chromatography methods.

As the epoxy resin (A), the epoxy resin (α) shown below is preferable.

(Epoxy resin (α))
The epoxy resin (α) is preferably a resin formed by reacting an epoxy compound with a phenolic compound, and can be obtained, for example, by a two-step method in which a bifunctional epoxy resin and a divalent hydroxyl group-containing compound are reacted. can. It can also be obtained by a one-step method in which two or more types of divalent hydroxyl group-containing compounds and epichlorohydrin are directly reacted. However, it is preferable to use the two-stage method, since it is easier to obtain epoxy resins with various molecular weights ranging from low molecular weight to high molecular weight than the one-stage method.

=Epoxy compound=
The above epoxy compound is preferably a compound having two or more epoxy groups in the molecule. Examples of such compounds include bifunctional epoxy compounds and polyfunctional epoxy compounds (trifunctional or more).

Examples of the above bifunctional epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol E diglycidyl ether, bisphenol C diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, and bisphenol AD diglycidyl ether. , bisphenol acetophenone diglycidyl ether, bisphenol trimethylcyclohexane diglycidyl ether, bisphenol fluorene diglycidyl ether, tetramethylbisphenol A diglycidyl ether, tetramethylbisphenol F diglycidyl ether, tetra-t-butylbisphenol A diglycidyl ether, tetramethylbisphenol Biphenol diglycidyl ethers such as S diglycidyl ether; biphenol diglycidyl ethers such as biphenol diglycidyl ether, tetramethylbiphenol diglycidyl ether, dimethylbiphenol diglycidyl ether, and tetra-t-butylbiphenol diglycidyl ether; hydroquinone Benzenediol-based diglycidyl ethers such as diglycidyl ether, methylhydroquinone diglycidyl ether, dibutylhydroquinone diglycidyl ether, resorcinol diglycidyl ether, methylresorcinol diglycidyl ether; dihydroanthrahydroquinone diglycidyl ether, dihydroxydiphenyl ether diglycidyl ether, thio Examples include diphenol diglycidyl ether, dihydroxynaphthalene diglycidyl ether, and the like.

Also, epoxy compounds in which hydrogen is added to the aromatic ring of the bifunctional epoxy compounds exemplified above; adipic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, methylhexahydrophthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, biphenyl Epoxy compounds produced from various carboxylic acids such as dicarboxylic acids and dimer acids, and epihalohydrin; Epoxy compounds produced from epihalohydrin and various amine compounds such as diaminodiphenylmethane, aminophenol, and xylene diamine; Glycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,5-pentanediol diglycidyl ether, poly Pentamethylene 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 (Poly)alkylene glycol diglycidyl ether consisting only of a chain structure such as glycidyl ether, 1,10-decanediol diglycidyl ether, 2,2-dimethyl-1,3-propanediol diglycidyl ether; 1,4-cyclohexane Also included are alkylene glycol diglycidyl ethers having a cyclic structure such as dimethanol diglycidyl ether.

Examples of the polyfunctional epoxy compounds include phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, naphthol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenylaralkyl type epoxy resin, dicyclopentadiene type Epoxy resins, phenol-modified xylene epoxy resins, trisphenolmethane epoxy resins, tetraphenol ethane epoxy resins, and condensation reactions between these various phenols and various aldehydes such as hydroxybenzaldehyde, crotonaldehyde, and glyoxal. Examples include epoxy resins using various phenolic compounds, such as polyhydric phenol resins obtained, co-condensation resins of heavy oils or pitches, phenols, and formaldehydes.

As the epoxy compound, only one type of the epoxy compounds exemplified above may be used, or two or more types may be used in combination in any combination and 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 reaction, and bisphenol-based diglycidyl ethers are preferred from the viewpoint of transparency of the epoxy resin layer. More preferred is bisphenol A diglycidyl ether, especially from the viewpoint of transparency and heat resistance of the epoxy resin layer.

=Phenol compound=
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.

Examples of the above-mentioned phenolic compounds include bisphenol A, bisphenol F, bisphenol E, bisphenol C, bisphenol Z, bisphenol S, bisphenol AD, bisphenolacetophenone, bisphenol trimethylcyclohexane, bisphenol fluorene, tetramethylbisphenol A, tetramethylbisphenol F, and tetramethylbisphenol. -Biphenols such as t-butylbisphenol A and tetramethylbisphenol S; Biphenols such as biphenol, tetramethylbiphenol, dimethylbiphenol, and tetra-t-butylbiphenol; Hydroquinone, methylhydroquinone, dibutylhydroquinone, resorcinol, methylresorcinol, etc. Benzenediols; dihydroanthrahydroquinones such as dihydroanthrahydroquinone; dihydroxydiphenyl ethers such as dihydroxydiphenyl ether; thiodiphenols such as thiodiphenol; dihydroxynaphthalenes such as dihydroxynaphthalene; dihydroxystilbenes such as dihydroxystilbene; phenol novolak Resins, bisphenol novolac resins such as cresol novolak resins and bisphenol A novolac resins; various types such as naphthol novolac resins, phenol aralkyl resins, terpene phenol resins, dicyclopentadiene phenol resins, phenol biphenylene resins, and phenol-modified xylene resins. Phenol resins and polyhydric phenol resins obtained by condensation reactions between these various phenols and various aldehydes such as hydroxybenzaldehyde, crotonaldehyde, and glyoxal; heavy oil or pitch, phenols, and formaldehyde. Examples include various phenolic compounds such as co-condensed resins with similar compounds.

As the phenolic compound, only one type of the phenolic compounds exemplified above may be used, or two or more types may be used in combination in any combination and ratio.
Among these, bisphenols are preferred from the viewpoint of obtaining a copolymer with a molecular weight suitable for film formation while suppressing gelation during reaction with the glycidyl ether, and from the viewpoint of transparency and heat resistance of the epoxy resin layer.

= Usage amount of epoxy compound and phenolic compound =
When preparing the epoxy resin (α), the amount of the phenol compound to be used is preferably 0.05 mol or more, more preferably 0.10 mol or more, and still more preferably 0.15 mol or more per 1.00 mol of the epoxy compound. Preferably, 0.20 mol or more is even more preferable.
On the other hand, the amount of the phenol 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 1.10 mol or less per 1.00 mol of the epoxy compound. Even more preferred.
It is preferable that the amount of the phenol compound used is equal to or higher than the above lower limit value from the viewpoint of molecular weight extension.In particular, when it is desired to obtain a low molecular weight epoxy compound within this range, the amount of the phenol compound should be reduced and a high molecular weight epoxy compound should be obtained. If it is desired to obtain an epoxy compound, the amount of the phenol compound may be increased.
On the other hand, if it is below the above upper limit, an epoxy compound with good curability can be easily obtained, which is preferable.

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

Specific examples of alkali metal compounds 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; Examples include alkali metal alkoxides such as 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.

Specific examples of organic phosphorus compounds include tri-n-propylphosphine, tri-n-butylphosphine, triphenylphosphine, tetramethylphosphonium bromide, tetramethylphosphonium iodide, tetramethylphosphonium hydroxide, trimethylcyclohexylphosphonium chloride, and trimethyl. Cyclohexylphosphonium bromide, trimethylbenzylphosphonium chloride, trimethylbenzylphosphonium bromide, tetraphenylphosphonium bromide, triphenylmethylphosphonium bromide, triphenylmethylphosphonium iodide, triphenylethylphosphonium chloride, triphenylethylphosphonium bromide, triphenylethylphosphonium iodide , triphenylbenzylphosphonium chloride, triphenylbenzylphosphonium bromide, and the like.

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

Specific examples of quaternary ammonium salts include tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, triethylmethylammonium chloride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrapropylammonium bromide, Examples include tetrapropylammonium hydroxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium hydroxide, benzyltributylammonium chloride, phenyltrimethylammonium chloride, etc. It will be done.

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

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.

The amount of the catalyst to be used is usually preferably 0.001 to 1% by mass based on the reaction solid content. By setting the usage amount of the catalyst to be equal to or more than the above lower limit value, it becomes easy to increase the molecular weight, and by making the usage amount of the catalyst to be equal to or less than the above upper limit value, it becomes easier to suppress gelation. Note that the reaction solid content refers to the total amount of reaction substrates other than the solvent in the reaction system.

=Solvent=
In preparing the epoxy resin (α), a solvent may be used in the reaction step between the epoxy compound and the phenol compound.
Examples of the above-mentioned solvent include the above-mentioned organic solvents.

=Reaction conditions=
The reaction between the epoxy compound and the phenol compound may be performed by a known method.
The reaction system may be under normal pressure, increased pressure, or reduced pressure.
Further, the reaction temperature is usually 80 to 240°C, preferably 100 to 220°C, more preferably 120 to 200°C. It is preferable that the reaction temperature is equal to or higher than the above lower limit because the reaction can easily proceed. Moreover, if the reaction temperature is below the above upper limit, side reactions will be difficult to proceed, which is preferable from the viewpoint of obtaining a highly pure epoxy compound.
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. It is preferable that the reaction time is less than or equal to the above upper limit in terms of improving production efficiency, and it is preferable that the reaction time is greater than or equal to the above lower limit in that unreacted components can be reduced.

(Molecular weight of epoxy resin (α))
The weight average molecular weight (weight average molecular weight before curing) of the epoxy resin (α) contained in the epoxy resin composition is preferably 2,000 to 300,000, more preferably 10,000 to 100,000. .
When the mass average molecular weight is at least the above lower limit, an epoxy resin layer with sufficient elasticity and elongation can be obtained. On the other hand, when it is below the above upper limit, a coating liquid suitable for efficient film formation can be obtained without any restrictions on the type of solvent.

(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, even more preferably 500 g/eq or more.

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, even more preferably 50,000 g/eq or less.

If the epoxy equivalent is at least the above lower limit, it is preferable from the viewpoint of flexibility of the epoxy compound, and if it is at most the above upper limit, the density between crosslinking points between epoxy groups will decrease when curing the epoxy compound-containing composition described below. This is preferable because it increases the hardness and makes it easier to obtain cured physical properties.
In the present invention, "epoxy equivalent" is defined as "the mass of an epoxy compound containing 1 equivalent of epoxy group" and can be measured according to JIS K7236:2009.

2. Isocyanate compound (B)
By containing the isocyanate compound (B) as a crosslinking agent, the epoxy resin composition can accelerate the curing speed. As a result, the resulting epoxy resin layer has good optical properties, heat resistance, and solvent resistance.
In the present invention, the term "crosslinking agent" refers to a component that contributes to the crosslinking reaction and/or chain lengthening reaction between the epoxy groups of the epoxy resin (A).

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; tolylene diisocyanate; Aromatic isocyanates such as xylylene diisocyanate and diphenylmethane diisocyanate; lysine triisocyanate and the like can be mentioned.
In addition, isocyanate compounds obtained by reacting the above-exemplified isocyanate compounds with compounds having active hydrogen atoms such as amino groups, hydroxyl groups, carboxyl groups, and water (e.g., adducts of isocyanate compounds, burettes of isocyanate compounds, etc.) ), or trimers to pentamers of the isocyanate compounds exemplified above (eg, isocyanurates of isocyanate compounds, etc.).

As the isocyanate compound (B), only one type of the isocyanate compounds exemplified above may be used, or two or more types may be used in combination in any combination and ratio.
Among these, compounds having 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 preferred.

The content of the isocyanate compound (B) is preferably 0.1 to 100 parts by weight, more preferably 1 to 80 parts by weight, and even more preferably 5 to 80 parts by weight, based on 100 parts by weight of the epoxy resin (A). It is 60 parts by mass.

3. Other Components 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 that fall under the above crosslinking agents), coupling agents, flame retardants, and antioxidants. agents, light stabilizers, plasticizers, reactive diluents, filled pigments, inorganic fillers, organic fillers and the like. The other components mentioned above can be used in appropriate combinations depending on the desired physical properties of the epoxy resin composition.

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

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

Examples of the above amine compounds include aliphatic primary, secondary, and tertiary amines, aromatic primary, secondary, and tertiary amines, cyclic amines, guanidines, urea derivatives, and the like. Triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, metaxylene diamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, Examples include dimethyl urea, guanylurea, and the like.

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

Examples of the imidazole compounds include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and benzimidazole. It will be done.

Examples of the above-mentioned amide compounds include dicyandiamide and derivatives thereof, polyamide resins, and the like.

The above-mentioned cationic polymerization initiator generates cations by heat or active energy ray irradiation, and includes, for example, aromatic onium salts. Specifically, anion components such as SbF ₆ ^- , BF ₄ ^- , AsF ₆ ^- , PF ₆ ^- , CF ₃ SO ₃ , B(C ₆ F ₅ ) ^4- and atoms such as iodine, sulfur, nitrogen, phosphorus, etc. Examples include compounds consisting of an aromatic cation component containing. Among these, diaryliodonium salts and triarylsulfonium salts are preferred.

Examples of the organic phosphine include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine, etc., and examples of the phosphonium salt include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate. , tetrabutylphosphonium/tetrabutylborate, etc., and examples of the tetraphenylboron salt include 2-ethyl-4-methylimidazole/tetraphenylborate, N-methylmorpholine/tetraphenylborate, and the like.

When using polyfunctional phenols, amine compounds, and acid anhydride compounds, the functional groups in the crosslinking agent (hydroxyl groups of polyfunctional phenols, amino groups of amine compounds, or It is preferable to use the acid anhydride compound so that the equivalent ratio of the acid anhydride group (acid anhydride group) of the acid anhydride compound is in the range of 0.01 to 1.5.

When an imidazole compound is used, it is preferably used in an amount of 0.001 to 10 parts by weight based on 100 parts by weight of all epoxy components.

When an amide compound is used, it is preferably used in an amount of 0.001 to 20% by weight based on 100% by weight of the epoxy resin composition.

When a cationic polymerization initiator is used, it is preferably used in an amount of 0.001 to 15 parts by weight based on 100 parts by weight of all epoxy components.

When organic phosphines are used, they are preferably used in an amount of 0.001 to 20% by weight based on 100% by weight of the epoxy resin composition.

(Leveling agent)
The above-mentioned epoxy resin composition may contain a leveling agent in order to improve the surface appearance when formed into a film. When a leveling agent is added to the epoxy resin composition, the contact angle of water droplets on the surface of the epoxy resin layer can also be controlled.
Examples of the leveling agent include silicone-based leveling agents such as silane coupling agents, polyacrylate-based leveling agents, and perfluoroalkyl-based leveling agents. As the leveling agent, only one of the above-mentioned leveling agents may be used, or two or more thereof may be used in combination in any combination and ratio. Among them, as leveling agents, silicone macromer-modified acrylate, polyether macromer-modified acrylate, and silicone are used. It is preferable to use polyether macromer modified acrylate or the like.

(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 preferably used so that the solid content concentration of the epoxy resin composition is 10 to 90% by mass, more preferably 20 to 80% by mass.

<Physical properties of cured product (epoxy resin layer)>
The epoxy resin layer of this film is a cured product obtained by curing the above-mentioned epoxy resin composition.
Note that "curing" in the present invention means intentionally curing the epoxy resin composition by heat and/or light. The degree of curing may be selected depending on the desired physical properties and application, and may be in a fully cured state or a semi-cured state, but the physical properties of the cured product will change even if heat treatment is performed in a post-process. Complete curing is preferred from the viewpoint of preventing damage.

In addition, whether the epoxy resin layer is completely cured is determined by the glass transition temperature when the temperature is raised and when the temperature is raised again when the glass transition temperature is measured using a differential scanning calorimeter in accordance with JIS K7121:2012. Can be confirmed. In the present invention, complete curing is defined as a case in which the glass transition temperature at the time of re-heating does not rise by 3°C or more from that at the time of temperature rise.

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

When the thickness of the epoxy resin layer is P and the thickness of the cured active energy ray resin layer is Q, the value of P/Q is preferably 1 or more, more preferably 5 or more, and 10 or more. It is more preferable that Further, the value of P/Q is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

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 epoxy resin layer has good heat resistance.

When the epoxy resin layer is used for electronic components such as displays, it is preferable that the epoxy resin layer has high transparency. From this viewpoint, the light transmittance of the epoxy resin layer at 400 nm is preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and even more preferably 88% or more.
Further, 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 according to JIS K7375:2008.

Further, the haze of the epoxy resin layer is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less. The haze of the epoxy resin layer is a value measured according to JIS K 7136:2000.

Also. The yellowness index (YI) of the epoxy resin layer is preferably 5 or less, preferably 3 or less, and even more preferably 1 or less. The yellowness index (YI) of the epoxy resin layer is a value measured according to JIS K7373:2008.

When the epoxy resin layer is used for electronic components such as flexible displays, it is preferable that the epoxy resin layer has bending resistance.
Bending resistance is evaluated in a repeated bending test, for example, by the minimum bending radius R that does not cause any cracks or bending marks when repeated bending tests are performed 200,000 times. 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, durability against bending when used in electronic components such as flexible displays will be good.

Further, it is preferable that the epoxy resin layer has a water droplet contact angle of 90 degrees or less on both surfaces. As long as the water droplet contact angle is within the range, problems such as poor adhesion are unlikely to occur even if a functional layer or wiring is provided in a subsequent process. From this point of view, the contact angle of water droplets on both surfaces of the epoxy resin layer is more preferably 85 degrees or less.

<Functional layer>
The film may have a functional layer on at least one side.
Examples of the functional layer include a hard coat layer, an antistatic layer, an antiglare layer, a low reflection layer, an antireflection layer, and an antifouling layer. The functional layer may be a single layer having the plurality of functions described above, or may be a stack of two or more layers having each function.

(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, radiation, or ultraviolet rays, or by heating, but from the viewpoint of molding time and productivity. , ultraviolet curable resin compositions are preferred.

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, and polyester (meth)acrylate compounds. ) acrylate compounds, copolymerized (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.
Among them, in order to obtain a curable resin that imparts excellent surface hardness, the curable resin composition is made of, for example, a polyfunctional (meth)acrylate compound, a polyfunctional urethane (meth)acrylate compound, or a polyfunctional epoxy (meth)acrylate. It is preferable to include a radical polymerizable curable compound such as a compound and a thermally polymerizable curable compound such as an alkoxysilane or an alkyl alkoxysilane.

Further, the curable resin composition may be an organic/inorganic hybrid curable resin composition in which the curable resin or curable compound contains an inorganic component. Examples of the organic/inorganic hybrid curable resin composition include those composed of a curable resin composition in which the curable resin or curable compound contains an inorganic component having a reactive functional group. Utilizing such an inorganic component having a reactive functional group, for example, this inorganic component can be copolymerized and crosslinked with a radically polymerizable monomer to create an organic-inorganic composite that simply contains an inorganic component in an organic binder. Compared to curable resin compositions, curing shrinkage is less likely to occur and high surface hardness can be exhibited. Furthermore, from the viewpoint of reducing curing shrinkage, it is also preferable to use an organic-inorganic hybrid curable resin composition containing ultraviolet-reactive colloidal silica as an inorganic component having a reactive functional group.

In addition to the above-mentioned curable resin or curable compound, the curable resin composition forming the hard coat layer contains a leveling agent, a photopolymerization initiator, a refractive index adjusting component, a lubricant, an antioxidant, an ultraviolet absorber, and an antistatic agent. , flame retardants, fillers, glass fibers, silica, and the like.

<<Production method of epoxy film>>
The method for producing the epoxy film of the present invention is not particularly limited, and for example, a coating solution made of the above-mentioned epoxy resin composition is applied to a base film, such as a release film, and cured, and then the epoxy resin layer is An epoxy film may be obtained by applying the above active energy ray-curable resin composition thereon, curing it, and peeling off the base film (release film) from the epoxy resin layer. Further, the active energy ray curable resin composition is applied onto the base film (release film) and cured, and the epoxy resin composition is applied onto the active energy ray curable resin cured product layer and cured. Alternatively, the epoxy film may be obtained by peeling off the base film (release film) from the active energy ray-curable resin cured product layer.
Note that the epoxy film can be used in the form of a structure in which it is attached to a base film, that is, in the form of an epoxy film with a base film.

The method for applying the coating liquid onto the base film may be a known method. Examples of the coating method include comma coating method, gravure coating method, reverse coating method, knife coating method, dip coating method, spray coating method, air knife coating method, spin coating method, roll coating method, printing method, slide coating method, Examples include a curtain coating method, a die coating method, a casting method, a bar coating method, and an extrusion coating method.

The curing conditions of the coating liquid may be adjusted as appropriate depending on the components and blending amount of the epoxy resin composition or the active energy ray-curable resin composition, but the curing conditions of the epoxy resin composition are 80 to 200°C and 1 to 100°C. The heating condition is preferably 180 minutes. In addition, when heating the epoxy resin composition, first 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. It is preferable to carry out heating in a two-stage process in order to reduce curing defects.

When curing the active energy ray-curable resin composition, it is preferable to remove the solvent and then irradiate the composition with active energy rays for curing. Examples of methods for removing the solvent include natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations thereof. Among 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, 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.

The active energy rays to be irradiated include the type of active energy ray-curable resin (especially the type of photopolymerizable functional group that the active energy ray-curable resin has), and the type of photopolymerization initiator if it contains a photopolymerization initiator. They are appropriately selected depending on the type and amount thereof. Specifically, 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 can be mentioned. Among these, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and it is possible to use photopolymerization equipment that is widely used in this field. It is preferable to select the type of line-curable resin.

Examples of the light source of the active 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, and a wavelength range of 380. Examples include an LED light source that emits light at ~440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.
The ultraviolet irradiation intensity is usually 10 to 3,000 mW/cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength range effective for activating a photocationic polymerization initiator or a photoradical polymerization initiator. The time for irradiating the light 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. be.

<Base film>
Examples of the base film include those in which a release layer is formed by applying a silicone resin release agent or the like to the surface of a thin sheet-like base material made of paper, resin, metal, or the like.
The base material is preferably paper or resin because it is inexpensive, easy to process, and easy to dispose of or recycle, and resin is more preferred from the viewpoint of transparency.

The above-mentioned paper includes, for example, wood-free paper, kraft paper, glassine paper, parchment paper, supercalendered kraft paper, etc. whose surface has been subjected to a silicone coating treatment.

As the above-mentioned resin film, for example, a film whose main component is polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyimide, or polycarbonate can be used.
Among the above, from the viewpoint of appearance, ease of processing, durability, heat resistance, cost, etc., it is preferable to include a resin film containing polyester as a main component.
Further, the resin film may have a single layer structure or a multilayer structure of two or more layers.

In addition, "main component resin" means the resin with the highest content among the resins constituting the base material, specifically 50% by mass or more, especially 70% by mass or more, among which 80% by mass or more, Among them, it refers to a resin that accounts for 90% by mass or more (including 100% by mass).

The above polyester is preferably one obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. The polyester may be a polyester consisting of one type of aromatic dicarboxylic acid and one type of aliphatic glycol, or may be a copolymerized polyester obtained by further copolymerizing one or more other components.
Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalene dicarboxylic acid, and examples of aliphatic glycols include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol.
On the other hand, dicarboxylic acids used as other components of the copolymerized polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, and sebacic acid, and glycol components include ethylene glycol, diethylene glycol, and propylene glycol. , butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like.
Additionally, oxycarboxylic acids such as p-oxybenzoic acid can also be used.

Typical polyesters include polyethylene terephthalate obtained by polycondensing terephthalic acid and ethylene glycol, polyethylene naphthalate obtained by polycondensing 2,6-naphthalene dicarboxylic acid and ethylene glycol, and the like.
The polyester film may be an unstretched 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.
Further, the polyester film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

Moreover, it is preferable that the base film is a release film that further includes a release layer as the outermost layer on the side that contacts the epoxy resin layer. Including the release layer improves the releasability between the epoxy resin layer and the release film.

The components of the release layer are not particularly limited, and may contain silicone compounds, fluorine compounds, waxes, surfactants, and the like. It is preferable to use a silicone compound because it has a good balance between price and mold release properties.
Furthermore, a release control agent may be used in combination to adjust the release properties of the release layer.
In addition, the above-mentioned release layer may be laminated directly on the base material, or may be laminated via another layer, and examples of other layers include an easy-adhesion layer and an antistatic layer. It will be done.

(Thickness of base film)
The thickness of the base film is preferably 5 to 300 μm, more preferably 20 to 150 μm. It is preferable that the thickness of the base film is equal to or greater than the above lower limit because handling properties are improved when applying the epoxy resin composition or when peeling the epoxy resin layer and the base film.
Moreover, it is preferable that it is below the said upper limit because a base film becomes hard to bend and material cost can be suppressed.

When the base film has a release layer, the thickness of the release layer after curing is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm.
It is preferable that the thickness of the release layer is equal to or greater than the lower limit, since the release property is good and the handling property when peeling off the epoxy resin layer is improved, so that a film with a good appearance can be obtained.
Moreover, if it is below the above-mentioned upper limit, there will be no problem in mold releasability and the cost of the mold release layer can be suppressed, which is preferable.

<Protective film>
The film may include 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 includes, for example, the configuration of protective film/functional layer/epoxy resin layer/cured active energy ray resin layer/base film.
Moreover, the protective film may consist of a single layer of the base material (protective film base material), and in addition to the protective film base material, it further includes an adhesive layer as the outermost layer on the side that contacts the epoxy resin layer. It may be a structure.

As the protective film base material, a resin film is preferable, and more specifically, a film whose main component is polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyimide, or polycarbonate is preferable. The specific structure of the resin film may be the same as that described for the base film.
In addition, when using a protective film base material as a single layer, a film having self-adhesiveness is preferable.

Constituent components of the adhesive layer are not particularly limited, but include, for example, rubber adhesives, acrylic adhesives, polyvinyl ether adhesives, urethane adhesives, silicone adhesives, and the like. More specifically, examples include acrylic resins, urethane resins, ethylene/vinyl acetate copolymer resins, and polyolefin resins.

<<Wound body>>
The epoxy film or the epoxy film with a base film of the present invention may be wound into a roll by winding it around a core to form a wound body.
The length of the epoxy film or the epoxy film with a base 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.
Moreover, the length of the epoxy film or the epoxy film with a base film of the present invention is preferably 10,000 m or less.

Note that the core refers to a cylindrical winding core used for winding the film. The material of the core is not particularly limited, and examples thereof include paper, resin-impregnated paper, acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenol resin, and inorganic-containing resin. Among them, acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenol resin, and inorganic-containing resin are used because they have a small coefficient of thermal expansion, high rigidity, low swelling property against humidity, and excellent winding properties. It is preferably made of resin such as.
When the core material is paper, desired characteristics can be easily obtained by coating the surface with a resin or the like. Furthermore, from the viewpoint of surface smoothness, it is also preferable that the core is a tube of resin-impregnated paper.

When constructing a wound body, the epoxy film or the epoxy film with a base film is attached to the 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 resin cured product layer is on the outside. Preferably, the film is wound.

<<Applications>>
This film has a low water droplet contact angle on both surfaces of the epoxy resin layer and has good adhesion to functional layers and wiring, so it can be suitably used in electronic component applications such as displays and printed wiring boards.

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

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

<Epoxy resin>
(A-1): An epoxy resin (“YL7852BT40” manufactured by Mitsubishi Chemical Corporation) containing bisphenol A type epoxy resin as a main component was used.

<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 a main component ("Takenate D-160N" manufactured by Mitsui Chemicals, Inc.) was used.
(B-3): 1-benzyl-2-phenylimidazole (“Curezol 1B2PZ” manufactured by Shikoku Kasei Co., Ltd.) was used.

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

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

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

<Photopolymerization initiator>
(F-1): IGM Resins B. V. "Omnirad 184" manufactured by Manufacturer Co., Ltd. was used.

<<Base film>>
(G-1): On one side of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil (registered trademark), thickness 125 μm), apply the release layer composition to a thickness of 0.5 μm after drying with a gravure roll. The base film (release film) was obtained by coating the film so as to have the following properties and drying it at 150° C. for 20 seconds to remove the solvent.
The above mold release layer composition includes 100 parts by mass of melamine resin paint ("RP-30-30", manufactured by Miwa Institute Co., Ltd.), and a curing agent ("CP-CATALYST", manufactured by Miba Institute Co., Ltd.). ) and 100 parts by mass of ethyl acetate were uniformly mixed.
(G-2): A base film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., SP-PET (registered trademark) O3-BU, thickness (100 μm)) consisting of a polyester film and a silicone release layer was used.

<<Preparation of epoxy film>>
[Example 1]
Urethane (meth)acrylate oligomer (E-1), photoinitiator (F-1), additive (C-1), solvent (D-1) and (D-2) in the proportions listed in Table 1. By mixing, a coating liquid for forming a layer of cured active energy ray resin was obtained. A coating solution for forming an active energy ray resin cured product layer is applied onto the release layer of the base film (G-1) obtained above using a gravure roll so that the thickness after drying is 3 μm, The solvent was removed by drying at 80° C. for 2 minutes. Thereafter, ultraviolet rays were irradiated so that the cumulative light amount was 500 mJ/cm ² to obtain a laminated film (base sheet) on which a cured active energy ray resin layer was laminated.
Next, the epoxy resin (A-1), crosslinking agents (B-1) and (B-2), additive (C-1), and solvents (D-1) and (D-2) were added as shown in Table 1. A coating solution for forming an epoxy resin layer was obtained by mixing in the following proportions. A coating solution for forming an epoxy resin layer was applied onto the cured active energy ray resin layer of the laminated film obtained above using an applicator, and then primary heating was performed at 80°C for 2 minutes using a constant temperature dryer, and then at 180°C. A hardening treatment was performed by secondary heating for 5 minutes, and an epoxy resin layer was formed by naturally cooling to room temperature (25° C.). In this way, an epoxy film with a base film of Example 1 was obtained. Further, a wound body was prepared by winding the epoxy film with a base film of Example 1 around a core (made of ABS resin) so that the epoxy resin layer was on the inside.
The thickness of the epoxy resin layer of the obtained epoxy film with base film was 35 μm. Further, the base film was peeled off from the obtained epoxy film with base film, and the glass transition point of the epoxy resin layer was measured. The glass transition point of the epoxy resin layer was 129°C, and the glass transition point upon re-heating was 129°C, confirming that it was completely cured.

[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 base film was 35 μm.
Further, the base film was peeled off from the obtained epoxy film with base film, and the glass transition point of the epoxy resin layer was measured. The glass transition point of the epoxy resin layer was 112°C, and the glass transition point upon re-heating was 110°C, confirming that it was completely cured.

[Comparative example 1]
An epoxy film with a base film and a wound body were produced in the same manner as in Example 1 except that the active energy ray resin cured product layer was not provided. The thickness of the epoxy resin layer of the obtained epoxy film with base film was 35 μm. Further, the base film was peeled off from the obtained epoxy film with base film, and the glass transition point of the epoxy resin layer was measured. The glass transition point was 128°C, and the glass transition point upon re-heating was 129°C, confirming that it was completely cured.

[Comparative example 2]
An epoxy film with a base film and a winding were prepared in the same manner as in Example 1 except that a base film (G-2) consisting of a polyester film and a silicone release layer was used and no active energy ray resin cured layer was provided. A rotating body was created. The thickness of the epoxy resin layer of the obtained epoxy film with base film was 35 μm. Further, the base film was peeled off from the obtained epoxy film with base film, and the glass transition point of the epoxy resin layer was measured. The glass transition point was 128°C, and the glass transition point upon re-heating was 129°C, confirming that it was completely cured.

<Evaluation items>
(1) Glass transition temperature and degree of hardening The glass transition temperature and degree of hardening of the epoxy resin layer are determined by the “midpoint glass transition temperature: Tmg” described in JIS K7121:2012 “Transition temperature measurement method for plastics”. Measured based on. Specifically, using a differential scanning calorimeter "DSC8500" manufactured by PerkinElmer Japan Co., Ltd., the temperature was raised at a rate of 10 °C/min from 20 to 250 °C, and then lowered at a rate of 10 °C/min to 0 °C. The temperature was raised again from 0 to 250°C at a rate of 10°C/min, and measurements were taken. When the glass transition temperature at the time of re-heating did not rise by 3° C. or more from that at the time of temperature rise, it was considered to be completely cured.

(2) Haze The haze of the epoxy film at 400 nm to 650 nm obtained by peeling the base film from the epoxy films with the base film of Examples and Comparative Examples was measured using a haze meter manufactured by Nippon Denshoku Kogyo Co., Ltd. Measured using "NDH 7000II".
The measurement was performed according to JIS (Haze: JIS K 7136:2000).

(3) Heat resistance test The epoxy films obtained by peeling the base film from the epoxy films with the base film of Examples and Comparative Examples were cut into 5 cm x 5 cm pieces and placed on a metal container.
The metal container covered with the epoxy film was placed in an oven heated to 120° C. and allowed to stand for 5 minutes. The container was removed from the oven and allowed to cool naturally to room temperature. The heat resistance was evaluated by checking whether the film curled after cooling.
A: No curling occurred.
B: Curl occurs.

(4) Flexibility (R)
Using a bending tester (manufactured by Yuasa System Equipment Co., Ltd., DLDMLH-FS), the epoxy films of Examples and Comparative Examples were subjected to a bending test of 200,000 times, and the minimum bending radius R without causing any cracks or bending marks was determined. was evaluated.
Note that in the epoxy films of Example 1 and Comparative Example 1, no cracks or bending marks occurred even when R = 1 mm, so they were written as "≦1" in Table 1.

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

(6) Water droplet contact angle The base film was removed from the epoxy film with the base film, and the water droplet contact angle of the epoxy film was measured using a contact angle meter "DropMaster 500" manufactured by Kyowa Interface Science Co., Ltd. Ion-exchanged water was used for the measurement. The measurement temperature was 25° C., the amount of ion-exchanged water dropped was 2 μL, and the contact angle of the water droplet was evaluated 1 second after the droplet landed. Three points were measured on each side of the epoxy film, and the average was calculated.
In Table 1, the surface that is not in contact with the base film (epoxy resin layer surface) is defined as the "surface" of the epoxy film, and the surface that is in contact with the base film (active energy ray resin cured product) is defined as the "surface" of the epoxy film. The layer side) is the "back side" of the epoxy film.

The epoxy film having the active energy ray resin cured material layer of the example was highly transparent, and no curling was observed even when a heat resistance test was conducted at a temperature below the glass transition point. Furthermore, the epoxy films of Examples also had excellent bending resistance.
On the other hand, in the epoxy film of the comparative example, curling with the air surface side of the epoxy resin convex occurred in the heat resistance test under the same conditions.

1 Base film 2 Active energy ray resin cured product layer 3 Epoxy resin layer 5 Epoxy film 10 Epoxy film with base film

Claims (17)

It has an epoxy resin layer and an active energy ray resin cured material layer,
The epoxy resin layer includes an epoxy resin (A) and an isocyanate compound-derived unit (B),
The active energy ray resin cured product layer is an epoxy film containing a urethane (meth)acrylate structural unit. The epoxy film according to claim 1, wherein the epoxy resin layer has a thickness of 1 to 1000 μm, and the active energy ray resin cured product layer has a thickness of 0.5 to 20 μm. The epoxy film according to claim 1 or 2, 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 resin cured product layer. 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 and a phenol compound. The epoxy film according to claim 4, wherein the epoxy compound is a compound having two or more epoxy groups in the molecule. The epoxy film according to claim 4 or 5, wherein the phenolic compound is a compound having two or more hydroxyl groups bonded to an aromatic ring. The epoxy film according to any one of claims 1 to 6, wherein the isocyanate compound-derived unit (B) is a compound-derived unit having an aliphatic isocyanate as its main skeleton. The epoxy film according to any one of claims 1 to 7, wherein the epoxy resin layer further contains a leveling agent. The epoxy film according to any one of claims 1 to 8, wherein the epoxy resin layer has a glass transition temperature of 100°C or higher. The epoxy film according to any one of claims 1 to 9, further comprising a functional layer on at least one side. Comprising the epoxy film and base film according to any one of claims 1 to 10,
An epoxy film with a base film, comprising a structure in which the epoxy resin layer is laminated on the base film via the active energy ray resin cured product layer. 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. a step of curing an active energy ray curable resin composition containing a urethane (meth)acrylate oligomer to form an active energy ray resin cured product layer;
forming an epoxy resin layer by coating and curing an epoxy resin composition containing an epoxy resin (A) and an isocyanate compound (B) on the active energy ray resin cured product layer. Production method. The method for producing an epoxy film according to claim 13, wherein the epoxy resin (A) has a weight average molecular weight of 2,000 to 300,000. 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. 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. A base sheet for laminating an epoxy resin layer containing an epoxy resin (A) and an isocyanate compound-derived unit (B),
The base sheet includes a cured active energy ray resin layer containing a urethane (meth)acrylate structural unit.