Construct

Abstract

To provide a structure having excellent peelability of a thin optical film.SOLUTION: A structure comprises a transfer film comprising a support film and an adhesive layer, and an optical film in contact with the adhesive layer. The peeling force of the transfer film from the optical film is made smaller by physicochemical treatment to the adhesive layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition. [Background technology]

[0002] In recent years, in the manufacturing process of electronic devices such as display devices such as liquid crystal displays and organic electroluminescence (EL) displays, a resin film (e.g., a thin optical film) is sometimes attached to the electronic device via an adhesive layer or the like, from the viewpoint of ease of processing and transportation in the manufacturing process. Conventionally, for example, a resin film is formed on a processing film such as PET (polyethylene terephthalate) by directly applying a coating liquid containing a resin component, and then the processing film is peeled off from the resin film and the resin film is attached to a desired electronic device for mounting. However, when the processing film is peeled off from the resin film in this manner, the peeling between the processing film and the resin film is not easy, and particularly when a thin optical film is used as the resin film, there is a problem that the thin optical film may break, crack, or fall off after peeling. In order to solve this problem, it is necessary to control the peeling force between the process film and the resin film to a small value at least immediately before the peeling. Patent Document 1 discloses a release laminate whose peel strength is reduced to about one-fourth by dripping water, and envisions its use as a processing film. Patent Document 2 discloses a structure that improves peel stability from a thin film substrate by reducing the peel force at both ends of a protective film relative to the central portion in the width direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-151076 [Patent Document 2] Japanese Patent Application Publication No. 2017-121777 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as can be seen from the materials disclosed in Patent Document 1, the release laminate itself does not contain any adhesive components, and is therefore considered unsuitable as a processing film for non-viscous objects such as resin films. Furthermore, in Patent Document 2, the peel force is controlled by embossing, which limits the area that can be controlled, and therefore it is thought that the design flexibility is narrowed.

[0005] In view of the above, an object of the present invention is to provide a structure that has excellent peelability for a thin optical film. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that in a structure comprising a processing film, a pressure-sensitive adhesive layer, and an optical film in this order, the above-mentioned problems can be solved by using a physicochemical treatment to reduce the peel force of the pressure-sensitive adhesive layer on the processing film immediately before peeling it from the optical film, and have completed the present invention. That is, the present invention provides the following [1] to

[10] . [1] A structure comprising a support film, a transfer film including an adhesive layer, and an optical film in contact with the adhesive layer, wherein the peel force of the transfer film to the optical film is reduced by a physicochemical treatment of the adhesive layer. [2] The structure according to [1] above, wherein the physicochemical treatment is a temperature change or energy ray irradiation. [3] The structure according to the above [2], wherein the pressure-sensitive adhesive layer is a temperature-sensitive pressure-sensitive adhesive layer whose peel strength decreases with a change in temperature. [4] The structure according to the above [3], wherein the peel strength of the heat-sensitive adhesive layer from the optical film at 23°C and 50% RH is 2000 mN / 50 mm or more. [5] The structure according to the above [3] or [4], wherein the peel strength of the heat-sensitive adhesive layer from the optical film at 10°C is 250 mN / 50 mm or less. [6] The structure according to the above [2], wherein the pressure-sensitive adhesive layer is an energy ray-curable pressure-sensitive adhesive layer that is cured by irradiation with the energy ray and has a reduced peel strength. [7] The structure according to [6] above, wherein the peel strength of the energy ray-curable pressure-sensitive adhesive layer from the optical film at 23°C, 50% RH before curing is 2000 mN / 50 mm or more. [8] The structure according to the above [6] or [7], wherein the peel strength of the energy ray-curable pressure-sensitive adhesive layer from the optical film at 23°C and 50% RH after curing is 250 mN / 50 mm or less. [9] The structure according to any one of the above [1] to [8], wherein the optical film is a plastic film made of a cured product of a curable resin composition containing a polymer component and a curable monomer.

[10] The structure according to any one of the above [1] to [9], wherein the optical film has a thickness of 0.1 to 20 μm. [Effects of the Invention]

[0007] According to the present invention, a structure that allows a thin optical film to be excellently peeled off can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions can be considered more preferred. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60." In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0010] [Construct] The structure of the present invention is a structure comprising a support film, a transfer film including an adhesive layer, and an optical film in contact with the adhesive layer, and is characterized in that the peel force of the transfer film from the optical film is reduced by physicochemical treatment of the adhesive layer. In the present invention, in a structure comprising a support film, a transfer film including a pressure-sensitive adhesive layer, and an optical film in contact with the pressure-sensitive adhesive layer, before peeling the optical film from the transfer film, a physicochemical treatment is performed, which is not particularly limited, but is preferably performed by changing the temperature or by curing through energy ray irradiation to reduce the peeling force of the transfer film to the optical film to a level at which peeling is possible, and even in the case of a thin optical film, the entire area of ​​the peeled surface after peeling can be made defect-free.

[0011] FIG. 1 is a cross-sectional view showing an example of the structure of the present invention. The construct 1 includes a support film 2, a transfer film 4 including a pressure-sensitive adhesive layer 3, and an optical film 5, in this order. The carrier film 6 is used, for example, as a support when the optical film 5 is formed and as a transport film during production.

[0012] (transfer film) <Adhesive layer> The transfer film in the structure of the present invention includes an adhesive layer. The pressure-sensitive adhesive layer used in the present invention has the property of reducing the peel strength of the transfer film by subjecting the pressure-sensitive adhesive layer to a physicochemical treatment. In one embodiment, the pressure-sensitive adhesive layer is preferably a temperature-sensitive adhesive layer whose peel strength is reduced by temperature change. In another embodiment, the pressure-sensitive adhesive layer used in the present invention is preferably an energy-ray-curable adhesive layer whose peel strength is reduced by being cured by energy ray irradiation.

[0013] <Thermosensitive adhesive layer> In the present invention, a temperature-sensitive adhesive whose peel strength changes in response to temperature change as a physicochemical treatment can be used in the adhesive layer. Examples of the temperature-sensitive adhesive include an adhesive containing a side-chain crystalline polymer, which exhibits the property of maintaining adhesion at temperatures above the melting point of the side-chain crystalline polymer and decreasing peel strength at temperatures below the melting point. The adhesive whose peel strength decreases with temperature change is a polymer that reversibly changes between a crystalline state and a fluid state in response to temperature change. The temperature-sensitive adhesive layer is an adhesive layer containing this side-chain crystalline polymer as the main component. Here, the melting point refers to the temperature at which a specific portion of a polymer that was initially aligned in an ordered arrangement becomes disordered through an equilibrium process. The melting point is a value obtained by measurement using a differential scanning calorimeter (DSC) at a measurement condition of 10°C / min. The melting point range is preferably room temperature (e.g., 25°C) or lower, more preferably 0°C or higher and 15°C or lower. If the melting point is too high, unintended peeling may occur, for example, during the manufacturing process or storage. On the other hand, if the melting point is too low, special measures may be required to prevent defects due to condensation or frosting.

[0014] The side-chain crystalline polymer is a polymer obtained by polymerizing a monomer (hereinafter sometimes referred to as "monomer") that constitutes the side-chain crystalline polymer. Examples of the monomer include (meth)acrylates having a linear alkyl group with 16 or more carbon atoms, (meth)acrylates having an alkyl group with 1 to 6 carbon atoms, and polar monomers. These may be used alone or in combination of two or more.

[0015] Examples of (meth)acrylates having a linear alkyl group with 16 or more carbon atoms include (meth)acrylates having a linear alkyl group with 16 to 22 carbon atoms, such as cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, and behenyl (meth)acrylate. Examples of the (meth)acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hexyl (meth)acrylate. Examples of polar monomers include ethylenically unsaturated monomers having a carboxyl group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; and ethylenically unsaturated monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxyhexyl (meth)acrylate.

[0016] The polymerization ratio of the monomers is preferably 30 to 100 parts by mass of a (meth)acrylate having a linear alkyl group with 16 or more carbon atoms, 0 to 70 parts by mass of a (meth)acrylate having an alkyl group with 1 to 6 carbon atoms, and 0 to 10 parts by mass of a polar monomer. The type of monomer and the polymerization ratio are preferably selected so that the melting point of the side-chain crystalline polymer obtained by polymerization is the above-mentioned predetermined temperature.

[0017] The polymerization method is not particularly limited, and examples thereof include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. For example, when solution polymerization is employed, the above-mentioned monomers are added to a solvent, mixed, and stirred at about 40 to 90°C for about 2 to 10 hours.

[0018] The weight average molecular weight of the polymer constituting the side chain crystalline polymer is preferably from 200,000 to 1,000,000, and more preferably from 400,000 to 700,000. The weight average molecular weight is a value obtained by measuring the polymer by gel permeation chromatography (GPC) and converting the obtained measurement value into polystyrene equivalent.

[0019] On the other hand, examples of materials that can be used to form a pressure-sensitive adhesive layer that, together with such a side-chain crystalline polymer, exhibits a reduced peel strength due to temperature changes include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-polypropylene copolymer, and polyvinyl chloride.

[0020] The thickness of the temperature-sensitive adhesive layer is not particularly limited, but is preferably from 2 μm to 200 μm, more preferably from 5 μm to 100 μm, and even more preferably from 10 μm to 50 μm. When the thickness is within this range, sufficient peel strength is easily obtained, and the adhesive layer tends to be less likely to deform due to heat treatment.

[0021] Temperature-sensitive adhesive layer 23 The peel strength against the optical film at °C and 50% RH is preferably 2000 mN / 50 mm or more, more preferably 3000 mN / 50 mm or more and 20000 mN / 50 mm or less, and even more preferably 5000 mN / 50 mm or more and 10000 mN / 50 mm or less. 23 When the peel strength to the optical film at °C and 50% RH is within this range, sufficient peel strength is obtained, and peeling is unlikely to occur during handling in the manufacturing process or during storage.

[0022] The peel strength of the heat-sensitive adhesive layer from an optical film at 10° C. is preferably 250 mN / 50 mm or less, more preferably 10 mN / 50 mm or more and 230 mN / 50 mm or less, and even more preferably 20 mN / 50 mm or more and 200 mN / 50 mm or less. When the peel strength from an optical film at 10° C. is within this range, the peel strength is sufficiently small, making it easy to peel the optical film, and preventing cracks, fissures, or falling off from occurring on the peeled surface after peeling, particularly in the case of a thin optical film. The peel strength (180° peel strength) can be measured by a method in accordance with JIS Z0237:2000.

[0023] <Energy ray curable adhesive layer> In the present invention, the adhesive layer can use an adhesive whose peel strength changes in response to energy ray irradiation (for example, ultraviolet ray irradiation or electron beam irradiation) as a physicochemical treatment. The energy ray-curable adhesive contains a component that hardens when irradiated with energy rays. As the energy ray-curable adhesive used in the energy ray-curable adhesive layer, it is particularly preferable to use an ultraviolet ray-curable adhesive. The energy ray-curable adhesive generally comprises an acrylic adhesive and an energy ray-polymerizable compound as main components. As the energy ray-polymerizable compound used in the energy ray-curable adhesive, for example, a low-molecular-weight compound having at least two or more photopolymerizable carbon-carbon double bonds in the molecule that can be three-dimensionally reticulated by light irradiation is used.

[0024] The acrylic pressure-sensitive adhesive contains an acrylic copolymer as its main component, such as a polymer obtained by polymerizing an alkyl ester of (meth)acrylic acid as its main component with a polar monomer (functional group-containing monomer) that can be copolymerized therewith.

[0025] As the alkyl ester of (meth)acrylic acid, an alkyl ester of (meth)acrylic acid having an alkyl group having 1 to 12 carbon atoms is preferably used. Specific examples include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, etc. Examples of polar monomers (functional group-containing monomers) include acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, etc. The acrylic copolymer may be used alone or in combination of two or more.

[0026] The weight-average molecular weight (Mw) of the acrylic copolymer is preferably 100,000 or more, more preferably 150,000 or more and 2,000,000 or less, and the glass transition temperature of the acrylic copolymer is usually 20°C or less, preferably -70°C or more and 10°C or less.

[0027] Specific examples of low molecular weight compounds having at least two photopolymerizable carbon-carbon double bonds in the molecule include trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and commercially available oligoester acrylates.

[0028] Furthermore, in addition to the above-mentioned acrylate compounds, urethane acrylate oligomers can also be used as the energy ray-polymerizable compound. The urethane acrylate oligomers can be obtained by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyester-type or polyether-type polyol compound with a polyvalent isocyanate compound (e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.), with an acrylate or methacrylate having a hydroxyl group (e.g., 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.).

[0029] The energy ray-curable adhesive layer may be formed from an energy ray-curable copolymer having an energy ray-polymerizable group in the side chain (hereinafter, sometimes referred to as an "adduct polymer"). Such an energy ray-curable copolymer has properties of both adhesiveness and energy ray curability. As the energy ray-curable copolymer having an energy ray-polymerizable group in the side chain, a known one can be appropriately used.

[0030] The energy beam-curable copolymer can be obtained by reacting an acrylic copolymer having a functional group-containing monomer in the side chain with a compound having a substituent reactive with the functional group and an energy beam-polymerizable group. Examples of such acrylic copolymers include copolymers of alkyl esters of (meth)acrylic acid and functional group monomers, as exemplified above for the acrylic copolymer. Examples of compounds having a substituent and an energy beam-polymerizable group include methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, glycidyl (meth)acrylate, and (meth)acrylic acid.

[0031] The weight average molecular weight (Mw) of the energy ray-curable copolymer is preferably 100,000 or more, and more preferably 150,000 to 2,000,000.The glass transition temperature of the acrylic copolymer is usually 20°C or less, and preferably -70°C or more and 10°C or less.

[0032] The energy ray curable adhesive preferably contains an acrylic adhesive and an energy ray polymerizable compound or an energy ray curable copolymer, and further contains a photopolymerization initiator. By using a photopolymerization initiator in the energy ray-curable adhesive layer, sufficient curing properties can be obtained even when ultraviolet (UV) rays are used as the energy rays to be irradiated, and peelability from the substrate can be improved. Specific examples of the photopolymerization initiator include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, 2-chloroanthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, etc. The photopolymerization initiators may be used alone or in combination of two or more.

[0033] The energy ray-curable pressure-sensitive adhesive may also contain other components within the scope of the present invention. Examples of other components include crosslinking agents, curing agents, inorganic fillers, organic fillers, plasticizers, antistatic agents, antioxidants, pigments, dyes, etc. These may be used alone or in combination of two or more.

[0034] The thickness of the energy ray-curable pressure-sensitive adhesive layer is not particularly limited, but is preferably from 2 μm to 200 μm, more preferably from 5 μm to 100 μm, and even more preferably from 10 μm to 50 μm. When the thickness of the energy ray-curable pressure-sensitive adhesive layer is in this range, sufficient peel strength is easily obtained, and the pressure-sensitive adhesive layer tends to be less likely to deform due to heat treatment.

[0035] Before the energy ray curable adhesive layer is cured 23 The peel strength against an optical film at °C and 50% RH is preferably 2000 mN / 50 mm or more, more preferably 3000 mN / 50 mm or more and 20000 mN / 50 mm or less, and even more preferably 5000 mN / 50 mm or more and 10000 mN / 50 mm or less. 23 When the peel strength to the optical film at °C and 50% RH is within this range, sufficient peel strength is obtained, and peeling is unlikely to occur during handling in the manufacturing process or during storage.

[0036] After the energy ray curable adhesive layer has hardened 23 The peel strength against an optical film at °C and 50% RH is 250 mN / 50 mm or less, more preferably 10 mN / 50 mm or more and 230 mN / 50 mm or less, and even more preferably 20 mN / 50 mm or more and 200 mN / 50 mm or less. 23 When the peel strength for an optical film at °C and 50% RH is within this range, the peel strength is sufficiently small, making it easy to peel the optical film, and no cracks, fissures, or falling off occur on the peeled surface, even in the case of a thin optical film. As mentioned above, the peel force (180° peel strength) can be measured by a method in accordance with JIS Z0237:2000.

[0037] <Support film> The support film used in the present invention is, for example, a support substrate for the pressure-sensitive adhesive layer in a transfer film.

[0038] Examples of support films include paper substrates such as glassine paper, coated paper, and fine paper; laminated paper obtained by laminating these paper substrates with thermoplastic resins such as polyethylene and polypropylene; the above paper substrates that have been sealed with cellulose, starch, polyvinyl alcohol, acrylic-styrene resin, and the like; plastic films such as polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polyethylene and polypropylene; and glass.

[0039] In addition, for ease of handling, the support film may be a paper substrate or a plastic film having a release layer provided on the side opposite to the side on which the pressure-sensitive adhesive layer is provided. The release layer can be formed using a conventionally known release agent such as a silicone-based release agent, a fluorine-based release agent, an alkyd-based release agent, or an olefin-based release agent. The thickness of the release agent layer is not particularly limited, but is usually 0.02 to 2.0 μm, more preferably 0.05 to 1.5 μm.

[0040] The thickness of the support film is preferably from 1 to 500 μm, more preferably from 5 to 300 μm, from the viewpoint of ease of handling.

[0041] The surface roughness Ra (arithmetic mean roughness) of the support film is preferably 20.0 nm or less, more preferably 10.0 nm or less, and the surface roughness Rt (maximum cross-sectional height) is preferably 500 nm or less, more preferably 250 nm or less. The surface roughness Ra and Rt are values ​​obtained by optical interferometry in a measurement area of ​​100 μm×100 μm.

[0042] (Optical film) The construction of the present invention includes an optical film. The optical film is preferably a plastic film made of a cured product of a curable resin composition containing a polymer component and a curable monomer. The optical film may be a single layer or a multi-layer film. The method for forming such an optical film will be described in detail in the method for producing a structure described later.

[0043] <Polymer component> The polymer component includes a thermoplastic resin. From the viewpoint of heat resistance, the thermoplastic resin is preferably a thermoplastic resin having a ring structure such as an aromatic ring structure or an alicyclic structure, and more preferably a thermoplastic resin having an aromatic ring structure, such as a polyimide resin, a polyarylate resin, a polysulfone resin, a polycarbonate resin, or an alicyclic hydrocarbon resin.

[0044] The use of polyimide resins (amorphous thermoplastic resins) makes it easier to obtain optical films with excellent transparency. They have a high glass transition temperature (Tg) (e.g., 250°C or higher) and excellent heat resistance, and are easily soluble in general-purpose organic solvents while still exhibiting good heat resistance. Here, the term "amorphous thermoplastic resin" refers to a thermoplastic resin whose melting point is not observed in differential scanning calorimetry. Tg refers to the temperature at the maximum point of tan δ (loss modulus / storage modulus) obtained by viscoelasticity measurement (measurement in tension mode in the range of 0 to 400°C at a frequency of 10 Hz and a heating rate of 3°C / min).

[0045] The polyimide resin is not particularly limited, and examples thereof include aromatic polyimide resins, aromatic (carboxylic acid component)-aliphatic cyclic (diamine component) polyimide resins, aliphatic cyclic (carboxylic acid component)-aliphatic cyclic (diamine component) polyimide resins, aliphatic cyclic polyimide resins, and fluorinated aromatic polyimide resins. In particular, polyimide resins having a fluoro group in the molecule, as described below, are preferred. Specifically, a polyimide resin obtained by using an aromatic diamine compound and a tetracarboxylic dianhydride, polymerizing the polyamic acid, and then chemically imidizing the polyamic acid is preferred.

[0046] Any aromatic diamine compound can be used as long as it is soluble in a common solvent (e.g., N,N-dimethylacetamide (DMAC)) and gives a polyimide having a predetermined transparency upon reaction with the tetracarboxylic dianhydride used in combination. Specifically, m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, 2-(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)-2-(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 3,4'-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenyl)]sulfone, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[ 4-(3-aminophenyl) sulfone, bis[4-(3-aminophenoxy)phenyl] ether, bis[4-(4-aminophenoxy)phenyl] ether, bis[3-(3-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] methane, bis[4-(4-aminophenoxy)phenyl] methane, bis[3-(3-aminophenoxy)phenyl] methane, bis[3-(4-aminophenoxy)phenyl] methane, 2,2-bis[4-(3-aminophenoxy)phenyl] propane, 2,2-bis[4 -(4-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3, Examples of such benzene derivatives include 3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

[0047] These aromatic diamine compounds may be used alone or in combination of two or more kinds thereof. From the viewpoint of transparency and heat resistance, preferred aromatic diamine compounds include 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3 Examples of aromatic diamine compounds having a fluoro group include 1,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. It is preferred that at least one of the aromatic diamine compounds used be an aromatic diamine compound having a fluoro group, with 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl being particularly preferred. Using an aromatic diamine compound having a fluoro group makes it easier to achieve transparency, heat resistance, and solubility in solvents.

[0048] As with the aromatic diamine compounds, any tetracarboxylic acid dianhydride can be used as long as it is soluble in common solvents (e.g., N,N-dimethylacetamide (DMAC)) and provides a polyimide having a predetermined transparency. Specific examples include 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,4-hydroquinonedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenylethertetracarboxylic dianhydride. These tetracarboxylic acid dianhydrides may be used alone, or two or more types of tetracarboxylic acid dianhydrides may be used together. From the viewpoints of transparency, heat resistance, and solubility in solvents, it is preferable to use a tetracarboxylic acid dianhydride having at least one type of fluoro group, such as 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride.

[0049] The polymerization to form polyamic acid can be carried out by reacting the aromatic diamine compound and tetracarboxylic dianhydride while dissolving the resulting polyamic acid in a solvent that the polyamic acid is soluble in. Examples of the solvent that can be used for the polymerization to form polyamic acid include N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, and dimethyl sulfoxide.

[0050] The polymerization reaction to form polyamic acid is preferably carried out in a reaction vessel equipped with a stirrer while stirring. Examples include a method of dissolving a predetermined amount of aromatic diamine compound in the solvent, adding tetracarboxylic dianhydride while stirring, and carrying out a reaction to obtain polyamic acid, a method of dissolving tetracarboxylic dianhydride in a solvent, adding aromatic diamine compound while stirring, and carrying out a reaction to obtain polyamic acid, and a method of alternately adding aromatic diamine compound and tetracarboxylic dianhydride and carrying out a reaction to obtain polyamic acid.

[0051] There are no particular restrictions on the temperature of the polymerization reaction to form polyamic acid, but it is preferably carried out at a temperature of 0 to 70° C., more preferably 10 to 60° C., and even more preferably 20 to 50° C. By carrying out the polymerization reaction within the above range, it is possible to obtain a high-molecular-weight polyamic acid that is less colored and has excellent transparency.

[0052] The aromatic diamine compound and tetracarboxylic dianhydride used in the polymerization to form polyamic acid are generally used in roughly equimolar amounts, but the molar ratio of tetracarboxylic dianhydride to aromatic diamine compound (molar ratio) can be varied within a range of 0.95 to 1.05 to control the degree of polymerization of the resulting polyamic acid. The molar ratio of tetracarboxylic dianhydride to aromatic diamine compound is preferably within a range of 1.001 to 1.02, more preferably 1.001 to 1.01. By using a slight excess of tetracarboxylic dianhydride relative to the aromatic diamine compound, the degree of polymerization of the resulting polyamic acid can be stabilized and units derived from the tetracarboxylic dianhydride can be positioned at the polymer terminals, resulting in a polyimide with little coloration and excellent transparency.

[0053] The concentration of the resulting polyamic acid solution is preferably adjusted to an appropriate concentration (for example, about 10 to 30% by mass) so that the viscosity of the solution is kept appropriate and handling in the subsequent steps is easy.

[0054] An imidizing agent is added to the resulting polyamic acid solution to carry out a chemical imidization reaction. Examples of imidizing agents that can be used include carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, and benzoic anhydride. Acetic anhydride is preferred from the standpoints of cost and ease of removal after the reaction. The equivalent weight of the imidizing agent used is equal to or greater than the equivalent weight of the amide bond in the polyamic acid to be subjected to the chemical imidization reaction, and is preferably 1.1 to 5 times, and more preferably 1.5 to 4 times, the equivalent weight of the amide bond. Using a slight excess of the imidizing agent relative to the amide bond in this way allows the imidization reaction to be carried out efficiently even at relatively low temperatures.

[0055] In the chemical imidization reaction, an aliphatic, aromatic, or heterocyclic tertiary amine such as pyridine, picoline, quinoline, isoquinoline, trimethylamine, triethylamine, etc. can be used as an imidization accelerator. By using such amines, the imidization reaction can be carried out efficiently at a low temperature, and as a result, coloration during the imidization reaction can be suppressed, making it easier to obtain a more transparent polyimide.

[0056] There are no particular restrictions on the temperature for the chemical imidization reaction, but it is preferably carried out at a temperature of 10° C. or higher but lower than 50° C., and more preferably at a temperature of 15° C. or higher but lower than 45° C. By carrying out the chemical imidization reaction at a temperature of 10° C. or higher but lower than 50° C., coloration during the imidization reaction is suppressed, and a polyimide with excellent transparency can be obtained.

[0057] Thereafter, if necessary, a poor solvent for polyimide is added to the polyimide solution obtained by the chemical imidization reaction to precipitate the polyimide into powder, followed by drying.

[0058] The polyimide resin is preferably soluble in a low-boiling organic solvent such as benzene or methyl ethyl ketone. In particular, it is preferably soluble in methyl ethyl ketone. When the polyimide resin is soluble in methyl ethyl ketone, a curable resin layer (described later) made of a cured product of the curable resin composition can be easily formed by coating and drying.

[0059] A polyimide resin containing a fluoro group is particularly preferred from the viewpoint that it is easily dissolved in a general-purpose organic solvent with a low boiling point such as methyl ethyl ketone, and a curable resin layer can be easily formed by a coating method. The polyimide resin having a fluoro group is preferably an aromatic polyimide resin having a fluoro group in the molecule, and preferably has a skeleton represented by the following chemical formula in the molecule. [ka]

[0060] Polyimide resins having a skeleton represented by the above chemical formula have an extremely high Tg exceeding 300°C due to the high rigidity of the skeleton. This can significantly improve the heat resistance of the curable resin layer. Furthermore, the skeleton is linear and relatively flexible, making it easy to increase the breaking elongation of the curable resin layer. Furthermore, the polyimide resins having the above skeleton contain fluoro groups, making them soluble in low-boiling point, general-purpose organic solvents such as methyl ethyl ketone. Therefore, they can be applied using a solution casting method to form a curable resin layer as a coating film, and the solvent can be easily removed by drying. Polyimide resins having a skeleton represented by the above chemical formula can be obtained by polymerization and imidization of the above-mentioned polyamic acid using 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride.

[0061] Polyarylate resin is a resin made of a polymer compound obtained by reacting an aromatic diol with an aromatic dicarboxylic acid or its chloride. Like polyimide resin, polyarylate resin has a relatively high Tg and relatively good elongation properties. There are no particular limitations on the polyarylate resin, and known polyarylate resins can be used.

[0062] Examples of aromatic diols include bis(hydroxyphenyl)alkanes such as bis(4-hydroxyphenyl)methane (bisphenol F), bis(3-methyl-4-hydroxyphenyl)methane, 1,1-bis(4'-hydroxyphenyl)ethane, 1,1-bis(3'-methyl-4'-hydroxyphenyl)ethane, 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), 2,2-bis(3'-methyl-4'-hydroxyphenyl)propane, 2,2-bis(4'-hydroxyphenyl)butane, and 2,2-bis(4'-hydroxyphenyl)octane; and bis(hydroxyphenyl)cycloalkanes such as 1,1-bis(4'-hydroxyphenyl)cyclopentane, 1,1-bis(4'-hydroxyphenyl)cyclohexane (bisphenol Z), and 1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclohexane.Bis(4-hydroxyphenyl)phenylmethane, bis(3-methyl-4-hydroxyphenyl)phenylmethane, bis(2,6-dimethyl-4-hydroxyphenyl)phenylmethane, bis(2,3,6-trimethyl-4-hydroxyphenyl)phenylmethane, bis(3-t-butyl-4-hydroxyphenyl)phenylmethane, bis(3-phenyl-4-hydroxyphenyl)phenylmethane, bis(3-fluoro-4-hydroxyphenyl)phenylmethane, bis(3-bromo-4-hydroxyphenyl)phenyl Methane, bis(4-hydroxyphenyl)-4-fluorophenylmethane, bis(3-fluoro-4-hydroxyphenyl)-4-fluorophenylmethane, bis(4-hydroxyphenyl)-4-chlorophenylmethane, bis(4-hydroxyphenyl)-4-bromophenylmethane, bis(3,5-dimethyl-4-hydroxyphenyl)-4-fluorophenylmethane, 1,1-bis(4'-hydroxyphenyl)-1-phenylethane [bisphenol P], 1,1-bis(3'-methyl-4'-hydroxyphenyl) )-1-phenylethane, 1,1-bis(3'-t-butyl-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(3'-phenyl-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(4'-hydroxyphenyl)-1-(4'-nitrophenyl)ethane, 1,1-bis(3'-bromo-4'-hydroxyphenyl)-1-phenylethane, 1,1-bis(4'-hydroxyphenyl)-1-phenylpropane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)diphenylmethane bis(hydroxyphenyl)phenylalkanes such as bis(4-hydroxyphenyl)dibenzylmethane; bis(hydroxyphenyl)ethers such as bis(4-hydroxyphenyl)ether and bis(3-methyl-4-hydroxyphenyl)ether; bis(hydroxyphenyl)ketones such as bis(4-hydroxyphenyl)ketone and bis(3-methyl-4-hydroxyphenyl)ketone; bis(hydroxyphenyl)sulfides such as bis(4-hydroxyphenyl)sulfide and bis(3-methyl-4-hydroxyphenyl)sulfide;Examples of suitable bis(hydroxyphenyl)sulfoxides include bis(4-hydroxyphenyl)sulfoxide and bis(3-methyl-4-hydroxyphenyl)sulfoxide; bis(hydroxyphenyl)sulfones such as bis(4-hydroxyphenyl)sulfone [bisphenol S] and bis(3-methyl-4-hydroxyphenyl)sulfone; and bis(hydroxyphenyl)fluorenes such as 9,9-bis(4'-hydroxyphenyl)fluorene and 9,9-bis(3'-methyl-4'-hydroxyphenyl)fluorene.

[0063] Examples of aromatic dicarboxylic acids or chlorides thereof include phthalic acid, isophthalic acid, terephthalic acid, 4,4'-biphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and chlorides thereof. The polyarylate resin used may be a modified polyarylate resin. Among these, a resin made of a polymer compound obtained by reacting 2,2-bis(4'-hydroxyphenyl)propane with isophthalic acid is preferred.

[0064] The polysulfone resin is a polymer having a sulfone group (-SO2-) in the main chain, and is not particularly limited, and any known resin can be used. Examples of polysulfone resins include polyethersulfone resins, polysulfone resins, polyphenylsulfone resins, etc. The polysulfone resin used in the present invention may be a modified polysulfone resin. Specific examples of polysulfone resins include resins made of polymer compounds having repeating units represented by the following (a) to (h): [ka]

[0065] [ka] The polysulfone resin is preferably a polyethersulfone resin or a polysulfone resin.

[0066] Polycarbonate-based resins are polymers having a carbonate group (-O-C(=O)-O-) in the main chain. There are no particular limitations on the polycarbonate-based resin, and known polycarbonate resins can be used. Examples of polycarbonate-based resins include aromatic polycarbonate resins and aliphatic polycarbonate resins. Among these, aromatic polycarbonate resins are preferred because of their excellent heat resistance, mechanical strength, transparency, etc. The aromatic polycarbonate resin can be obtained by reacting an aromatic diol with a carbonate precursor by an interfacial polycondensation method or a melt transesterification method, by polymerizing a carbonate prepolymer by a solid-phase transesterification method, or by polymerizing a cyclic carbonate compound by a ring-opening polymerization method. Examples of the aromatic diol include those exemplified for the polyarylate resin. Examples of carbonate precursors include carbonyl halides, carbonate esters, and haloformates, and specific examples include phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

[0067] Alicyclic hydrocarbon resins are polymers having cyclic hydrocarbon groups in the main chain. The alicyclic hydrocarbon resin is not particularly limited, and known resins can be used. Examples of alicyclic hydrocarbon resins include monocyclic olefin polymers, norbornene polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrogenated versions of these. Specific examples include APEL (ethylene-cycloolefin copolymer manufactured by Mitsui Chemicals), ARTON (norbornene polymer manufactured by JSR Corporation), and ZEONOR (norbornene polymer manufactured by Nippon Zeon Co., Ltd.). The thermoplastic resins can be used alone or in combination of two or more.

[0068] Among the above-mentioned polymer components, polyimide resins are particularly preferred because they have high Tg and excellent heat resistance, and it is easy to obtain a resin that is soluble in general-purpose organic solvents while exhibiting good heat resistance.

[0069] (curable monomer) The curable monomer is a monomer having a polymerizable unsaturated bond and capable of participating in a polymerization reaction, or a polymerization reaction and a crosslinking reaction. In this specification, the term "curing" refers to a broad concept including the "polymerization reaction of a monomer" or the "polymerization reaction of a monomer and the subsequent crosslinking reaction of the polymer."

[0070] The molecular weight of the curable monomer is usually 3,000 or less, preferably 150 to 2,000, and more preferably 150 to 1,000. The number of polymerizable unsaturated bonds in the curable monomer is not particularly limited. The curable monomer may be a monofunctional monomer having one polymerizable unsaturated bond, or a multifunctional monomer having multiple polymerizable unsaturated bonds, such as a bifunctional or trifunctional monomer.

[0071] The monofunctional monomer includes a monofunctional (meth)acrylic acid derivative. The monofunctional (meth)acrylic acid derivative is not particularly limited, and known compounds can be used, such as monofunctional (meth)acrylic acid derivatives having a nitrogen atom, monofunctional (meth)acrylic acid derivatives having an alicyclic structure, and monofunctional (meth)acrylic acid derivatives having a polyether structure.

[0072] Examples of the monofunctional (meth)acrylic acid derivative having a nitrogen atom include compounds represented by the following formula:

[0073] [ka]

[0074] In the formula, R 1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 2 and R 3each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms; R 2 and R 3 may be bonded to form a ring structure, R 4 represents a divalent organic group. R 1 Examples of the alkyl group having 1 to 6 carbon atoms represented by the formula include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred. R 2 and R 3 Examples of the organic group having 1 to 12 carbon atoms represented by the formula (I) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, and propyl; cycloalkyl groups having 3 to 12 carbon atoms, such as cyclopentyl and cyclohexyl; and aromatic groups having 6 to 12 carbon atoms, such as phenyl, biphenyl, and naphthyl. These groups may have a substituent at any position. In addition, R 2 and R 3 may be joined together to form a ring, and the ring may further have a nitrogen atom or an oxygen atom in the skeleton. R 4 The divalent organic group represented by -(CH2) m -, -NH-(CH2) m In this case, m is an integer of 1 to 10.

[0075] Among these, (meth)acryloylmorpholine represented by the following formula is preferred as the monofunctional (meth)acrylic acid derivative having a nitrogen atom.

[0076] [ka]

[0077] By using a monofunctional (meth)acrylic acid derivative having a nitrogen atom as the curable monomer, a curable resin layer having better heat resistance can be formed.

[0078] Examples of the monofunctional (meth)acrylic acid derivative having an alicyclic structure include compounds represented by the following formula:

[0079] [ka]

[0080] In the formula, R 1 has the same meaning as above, and R 5 is a group having an alicyclic structure. R 5 Examples of the group having an alicyclic structure represented by the formula (I) include a cyclohexyl group, an isobornyl group, a 1-adamantyl group, a 2-adamantyl group, and a tricyclodecanyl group.

[0081] Specific examples of monofunctional (meth)acrylic acid derivatives having an alicyclic structure include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 1-adamantyl (meth)acrylate, and 2-adamantyl (meth)acrylate.

[0082] By using a monofunctional (meth)acrylic acid derivative having an alicyclic structure as a curable monomer, an optical film with more excellent optical properties can be formed.

[0083] Examples of the monofunctional (meth)acrylic acid derivative having a polyether structure include compounds represented by the following formula:

[0084] [ka]

[0085] In the formula, R 1 has the same meaning as above, and R 6 represents an organic group having 1 to 12 carbon atoms. 6 Examples of the organic group having 1 to 12 carbon atoms represented by the formula (I) include alkyl groups having 1 to 12 carbon atoms such as methyl, ethyl, and propyl groups; cycloalkyl groups having 3 to 12 carbon atoms such as cyclohexyl groups; and aromatic groups having 6 to 12 carbon atoms such as phenyl, biphenyl, and naphthyl groups. j represents an integer of 2 to 20.

[0086] Specific examples of monofunctional (meth)acrylic acid derivatives having a polyether structure include ethoxylated o-phenylphenol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and phenoxypolyethylene glycol (meth)acrylate.

[0087] By using a monofunctional (meth)acrylic acid derivative having a polyether structure as the curable monomer (B), an optical film having excellent toughness can be formed.

[0088] The polyfunctional monomer includes polyfunctional (meth)acrylic acid derivatives. The polyfunctional (meth)acrylic acid derivative is not particularly limited, and known compounds can be used, for example, di- to hexa-functional (meth)acrylic acid derivatives. Examples of the bifunctional (meth)acrylic acid derivative include compounds represented by the following formula:

[0089] [ka]

[0090] In the formula, R 1 means the same as above, and R 7 represents a divalent organic group. 7 Examples of the divalent organic group represented by the formula include groups represented by the following formula:

[0091] [ka]

[0092] (In the formula, s represents an integer of 1 to 20, t represents an integer of 1 to 30, u and v each independently represent an integer of 1 to 30, and "-" at both ends represents a bond.)

[0093] Specific examples of the bifunctional (meth)acrylic acid derivative represented by the above formula include tricyclodecane dimethanol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, etc. Among these, from the viewpoint of heat resistance and toughness, tricyclodecane dimethanol di(meth)acrylate and the like, which have R 7 and propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, etc., in which R 7 and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, etc., in which R 7 Preferably, the divalent organic group represented by the following formula has a 9,9-bisphenylfluorene skeleton.

[0094] Other examples of bifunctional (meth)acrylic acid derivatives include neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, di(acryloxyethyl) isocyanurate, and allylated cyclohexyl di(meth)acrylate.

[0095] Examples of trifunctional (meth)acrylic acid derivatives include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, and tris(acryloxyethyl)isocyanurate. Examples of tetrafunctional (meth)acrylic acid derivatives include pentaerythritol tetra(meth)acrylate. Examples of the pentafunctional (meth)acrylic acid derivatives include propionic acid-modified dipentaerythritol penta(meth)acrylate. Examples of the hexafunctional (meth)acrylic acid derivative include dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0096] A cyclopolymerizable monomer may be used as the curable monomer. The cyclopolymerizable monomer is a monomer that has the property of undergoing radical polymerization while undergoing cyclization. Examples of the cyclopolymerizable monomer include non-conjugated dienes, and for example, an α-allyloxymethylacrylic acid-based monomer can be used. C1-4 alkyl esters of 2-allyloxymethylacrylic acid and cyclohexyl 2-(allyloxymethyl)acrylate are preferred, C1-4 alkyl esters of 2-allyloxymethylacrylic acid are more preferred, and methyl 2-(allyloxymethyl)acrylate is even more preferred. Cyclopolymerizable monomers such as dimethyl-2,2'-[oxybis(methylene)]bis-2-propenoate, diethyl-2,2'-[oxybis(methylene)]bis-2-propenoate, di(n-propyl)-2,2'-[oxybis(methylene)]bis-2-propenoate, di(i-propyl)-2,2'-[oxybis(methylene)]bis-2-propenoate, di(n-butyl)-2,2'-[oxybis(methylene)]bis-2-propenoate, di(n-hexyl)-2,2'-[oxybis(methylene)]bis-2-propenoate, and dicyclohexyl-2,2'-[oxybis(methylene)]bis-2-propenoate can also be used.

[0097] The curable monomers can be used alone or in combination of two or more. Among these, the curable monomer is preferably a polyfunctional monomer, since it can provide an optical film having excellent heat resistance and solvent resistance. As the polyfunctional monomer, a bifunctional (meth)acrylic acid derivative is preferred, since it is easily mixed with the polymer component, and the polymer is less likely to undergo shrinkage upon curing, thereby suppressing curling of the cured product. It is more preferable that the curable monomer contains a polyfunctional (meth)acrylate compound and a cyclopolymerizable monomer. By using these in combination, it becomes easier to adjust the breaking elongation of the optical film while appropriately adjusting the heat resistance of the optical film. When the curable monomer contains a polyfunctional monomer, the content thereof is preferably 40% by mass or more, more preferably 50 to 100% by mass, of the total amount of the curable monomer.

[0098] The curable resin composition can be prepared by mixing a polymer component, a curable monomer, and, if desired, a polymerization initiator and other components described below, and dissolving or dispersing the mixture in an appropriate solvent.

[0099] The total content of the polymer component and the curable monomer in the curable resin composition is preferably 40 to 99.5 mass%, more preferably 60 to 99 mass%, and even more preferably 80 to 98 mass%, based on the mass of the entire curable resin composition excluding the solvent.

[0100] The content of the polymer component and the curable monomer in the curable resin composition, in terms of the mass ratio of the polymer component to the curable monomer, is preferably polymer component:curable monomer=20:80 to 90:10, more preferably 30:70 to 70:30. When the mass ratio of polymer component to curable monomer in the curable resin composition is within this range, the heat shrinkage rate of the optical film before and after heat treatment at high temperature tends to decrease, and the breaking elongation tends to be maintained. The content of the thermoplastic resin in the polymer component is preferably 70 to 100 mass %, more preferably 80 to 100 mass %, and even more preferably 95 to 100 mass %, based on the mass of the entire polymer component excluding the solvent.

[0101] The curable resin composition may contain a polymerization initiator if desired. The polymerization initiator may be any initiator that initiates a curing reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator.

[0102] Examples of the thermal polymerization initiator include organic peroxides and azo compounds. Examples of organic peroxides include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, and dicumyl peroxide; diacyl peroxides such as acetyl peroxide, lauroyl peroxide, and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; and peroxides such as 1,1-bis(t-butylperoxy)cyclohexane. Examples of the peroxyester include ketals; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, and 2,5-dimethylhexane-2,5-dihydroperoxide; and peroxyesters such as t-butyl peroxyacetate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, and t-butyl peroxyisopropyl carbonate. Examples of azo compounds include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile.

[0103] Photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamine, and the like. Alkylphenone-based photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, ethyl (2,4,6-trimethylbenzoyl)-phenylphosphine phosphate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; bis(η 5Titanocene photopolymerization initiators such as (2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl]titanium; oxime ester photopolymerization initiators such as 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime); benzophenone, p-chlorobenzophenone, benzoylbenzoic acid, methyl o-benzoylbenzoate, 4-methylbenzophenone, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl benzophenone-based photopolymerization initiators such as 13-acryloyl-4'-methyl-diphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, 2,4,6-trimethylbenzophenone, and 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone; and thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone.

[0104] Among the above photopolymerization initiators, phosphorus-based photopolymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)-phenylphosphineate, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide are preferred.

[0105] The content of the polymerization initiator is preferably from 0.05 to 15 mass %, more preferably from 0.05 to 10 mass %, and even more preferably from 0.05 to 5 mass %, based on the total amount of the curable resin composition.

[0106] The curable resin composition may contain a photopolymerization initiation aid such as triisopropanolamine or 4,4'-diethylaminobenzophenone in addition to the polymer component, curable monomer, and polymerization initiator.

[0107] The solvent used in preparing the curable resin composition is not particularly limited, and examples thereof include aliphatic hydrocarbon solvents such as n-hexane and n-heptane; aromatic hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as dichloromethane, ethylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, and monochlorobenzene; alcohol solvents such as methanol, ethanol, propanol, butanol, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; and ether solvents such as 1,3-dioxolane.

[0108] The content of the solvent in the curable resin composition is not particularly limited, but is usually 0.1 to 1,000 g, preferably 1 to 100 g, per 1 g of the polymer component. By appropriately adjusting the amount of the solvent, the viscosity of the curable resin composition can be adjusted appropriately.

[0109] The curable resin composition may further contain known additives such as plasticizers, antioxidants, and ultraviolet absorbers, within the scope of not impairing the objects and effects of the present invention.

[0110] The thickness of the optical film is preferably 0.1 to 20 μm, more preferably 0.1 to 10 μm, and even more preferably 0.1 to 5 μm. When the thickness of the optical film is within this range, it is preferable that the optical film does not become a factor in increasing the overall thickness of the electronic device when applied to electronic devices such as display devices that require thinner thicknesses.

[0111] The total light transmittance of the optical film is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The haze value of the optical film is preferably 2.0% or less, more preferably 1.0% or less, and even more preferably 0.5% or less. When the total light transmittance and haze value are within these ranges, the film can be used as an optical film or substrate for electronic devices such as display devices, which require high transparency. The total light transmittance can be measured in accordance with JIS K7361-1:1997, and the haze value can be measured in accordance with JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH-7000").

[0112] <Carrier film> The carrier film used in the present invention serves as a supporting substrate for the optical film. The same film as the above-mentioned process film can be used, and the preferred thickness, surface roughness Ra (arithmetic mean roughness), and surface roughness Rt (maximum cross-sectional height) are also the same.

[0113] <Method of manufacturing the component> One example of a method for producing a composite of the present invention includes the following (Step 1) to (Step 5). (Step 1): A step of forming an optical film (coating film) on a carrier film using a curable resin composition containing a polymer component and a curable monomer. (Step 2): A step of curing the optical film (coating film) obtained in Step 1 to form an optical film. (Step 3): A step of forming an adhesive layer on a support film to prepare a transfer film. (Step 4): A step of bonding the surface of the adhesive layer of the transfer film obtained in Step 3 to the surface of the optical film obtained in Step 2. (Step 5): A step of peeling off the carrier film from the laminate consisting of the transfer film, optical film, and carrier film obtained in Step 4 to obtain a composite.

[0114] In step 1, the method for applying the curable resin composition onto the carrier film is not particularly limited, and any known application method can be used, such as spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating. The method for drying the resulting coating film is not particularly limited, and any conventionally known drying method such as hot air drying, hot roll drying, or infrared irradiation can be used. The temperature for drying the coating film is usually 30 to 150°C, and preferably 80 to 130°C.

[0115] In step 2, the method for curing the optical film (coating film) is not particularly limited, and any known method can be used. For example, when the optical film (coating film) is formed using a curable resin composition containing a thermal polymerization initiator, the optical film (coating film) can be cured by heating the optical film (coating film). The heating temperature is usually 30 to 150°C, preferably 50 to 130°C. In addition, when the optical film (coating film) is formed using a curable resin composition containing a photopolymerization initiator, the optical film (coating film) can be cured by irradiating the optical film (coating film) with active energy rays. The active energy rays can be irradiated using a high-pressure mercury lamp, an electrodeless lamp, a xenon lamp, etc.

[0116] The wavelength of the active energy rays is preferably 200 to 400 nm, more preferably 350 to 400 nm. The irradiation dose is usually an illuminance of 50 to 1,000 mW / cm. 2 , light intensity 50~5,000mJ / cm 2 , preferably 1,000 to 5,000 mJ / cm 2 The irradiation time is usually 0.1 to 1,000 seconds, preferably 1 to 500 seconds, and more preferably 10 to 100 seconds. In consideration of the heat load in the light irradiation step, irradiation may be carried out multiple times to satisfy the above-mentioned light amount. In this case, in order to prevent deterioration of the polymer component due to irradiation with active energy rays and coloring of the optical film (coating), the curable resin composition may be irradiated with active energy rays through a filter that absorbs light of wavelengths unnecessary for the curing reaction. According to this method, light of wavelengths unnecessary for the curing reaction and that deteriorate the polymer component is absorbed by the filter, so deterioration of the polymer component is suppressed and a colorless and transparent optical film can be easily obtained. The filter may be a resin film such as a polyethylene terephthalate film. When a resin film is used, it is preferable to provide a step of laminating a resin film such as a polyethylene terephthalate film on the optical film (coating film) between steps 1 and 2. The resin film is usually peeled off after step 2.

[0117] The optical film (coating film) can also be cured by irradiating it with an electron beam. When irradiating with an electron beam, the optical film (coating film) can usually be cured without using a photopolymerization initiator. When irradiating with an electron beam, an electron beam accelerator or the like can be used. The irradiation dose is usually in the range of 10 to 1,000 krad. The irradiation time is usually 0.1 to 1,000 seconds, preferably 1 to 500 seconds, and more preferably 10 to 100 seconds.

[0118] The optical film (coating film) may be cured in an inert gas atmosphere such as nitrogen gas, if necessary. By performing the curing in an inert gas atmosphere, it becomes easier to avoid oxygen, moisture, etc. from interfering with the curing.

[0119] In step 3, a coating liquid having a suitable viscosity is prepared by dissolving components containing the desired adhesive in a solvent, and the coating liquid is applied to a support film and dried to form an adhesive layer. The method for applying the coating liquid to the support film is not particularly limited, and known application methods such as a knife coater, roll coater, roll knife coater, die coater, curtain coater, gravure coater, and rod coater can be used. The method for drying the obtained coating film is not particularly limited, and any conventionally known drying method can be used. The drying temperature for the coating film is usually 30 to 150°C, preferably 50 to 100°C.

[0120] In step 4, the method for bonding the surface of the adhesive layer of the transfer film to the surface of the optical film obtained in step 2 is not particularly limited, and known bonding methods such as room temperature lamination and heat lamination can be used.

[0121] In step 5, the method for peeling the carrier film from the optical film in the laminate is not particularly limited, and any known peeling method can be used. [Example]

[0122] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0123] The peel strength of the pressure-sensitive adhesive layer of the structures produced in the Examples and Comparative Examples from the optical film and the visual evaluation of the optical film after peeling were performed by the following methods.

[0124] (1) Peeling force The structures prepared in Examples and Comparative Examples are cut into a width of 50 mm and a length of 150 mm, and the surface of the structure on the optical film side is fixed to a glass plate of a size larger than the structure to prepare a test piece.Next, under a predetermined environment, the pressure-sensitive adhesive layer of the test piece and the optical film are peeled off using a high-speed peel tensile tester (manufactured by Tester Sangyo Co., Ltd., product name "High-speed Peel Tester TE-701") under the conditions of a peel angle of 180° and a peel speed of 300 mm / min, and the peel force (mN / 50 mm) at this time is measured.In addition, the same measurement is also performed on the structures that have been subjected to temperature treatment and energy ray irradiation. (2) Visual evaluation The structures prepared in the examples and comparative examples were cut to a width of 50 mm and a length of 150 mm, and the adhesive layer was subjected to predetermined physicochemical treatments (temperature change, energy ray irradiation), after which the optical film was peeled off from the adhesive layer (peeling conditions: peeling angle 180°, peeling speed 300 mm / min). The surface opposite to the peeled surface of the optical film obtained after peeling was placed on a blackboard, and the optical film was visually observed under a white LED light to determine whether or not cracks, fissures, or peeling had occurred, according to the following evaluation criteria. A: There are absolutely no defects such as cracks, chips, or falling off. B: Defects such as cracks, fissures, and falling off have occurred.

[0125] Example 1 <Preparation of construct> A curable resin composition was prepared as follows. As a polymer component, 100 parts by mass of polyimide resin pellets (Kawamura Sangyo Co., Ltd., product name "KPI-MX300F", Tg = 354°C, weight average molecular weight 190,000) were dissolved in methyl ethyl ketone (MEK) to prepare a 15% by mass solution of polyimide resin. Next, 122 parts by mass of tricyclodecane dimethanol diacrylate (Shin-Nakamura Chemical Co., Ltd., A-DCP, molecular weight 304.4) as a curable monomer and 5 parts by mass of (2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BASF, Irgacure TPO) as a polymerization initiator were added to this solution and mixed to prepare a curable resin composition. The curable monomer and polymerization initiator did not contain solvent, and all raw materials were 100% solids. Next, a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET50A-4160", thickness 50 μm) having an easy-adhesion layer on one side was used as a carrier film, and the curable resin composition prepared above was applied to the side of this PET film opposite to the easy-adhesion layer side, and the coating film of the obtained optical film was heated at 100°C for 2 minutes and dried. Then, a high-pressure mercury lamp (manufactured by iGraphics, product name "H04-L41") was used to measure the light with a wavelength of 365 nm and an illuminance of 130 mW / cm 2 , light intensity 700mJ / cm 2The composition was irradiated with ultraviolet light under conditions of a UV actinometer (UV Power Puck (registered trademark) II, manufactured by Heraus) in a nitrogen atmosphere to carry out a curing reaction, thereby forming an optical film with a thickness of 5 μm. Furthermore, the adhesive layer surface of a transfer film (manufactured by Nitta Corporation, product name "Intelimer CS5010C25 (cool-off type)", PET film thickness: 100 μm, temperature-sensitive adhesive layer thickness: 10 μm) having a temperature-sensitive adhesive layer on a support film (PET film) was thermally laminated at 70°C to the surface of the optical film opposite to the surface on which the carrier film was placed. Next, the carrier film was peeled off from the optical film to obtain a composite. Using the obtained structure, the peel strength of the heat-sensitive adhesive layer from the optical film at 23°C 50% RH, and the peel strength of the heat-sensitive adhesive layer from the optical film at 10°C when a structure of the same specifications prepared separately was cooled to 10°C (held for 10 minutes) were evaluated using the evaluation methods described above. Furthermore, the optical film peeled from the heat-sensitive adhesive layer at 10° C. was visually evaluated for cracks, fissures, falling off, etc. using the evaluation methods described above. The results are shown in Table 1.

[0126] Example 2 A structure was obtained in the same manner as in Example 1, except that a polyethylene terephthalate film (thickness: 100 μm) was used as the support film and an adhesive sheet (manufactured by Lintec Corporation, product name "Adwill D-241") using an energy ray-curable adhesive for the adhesive layer (thickness: 10 μm) was used as the transfer film. Using the obtained structure, the peel strength of the transfer film to the optical film at 23°C and 50% RH before curing was measured. The adhesive layer of the transfer film of a structure of the same specifications was also measured using an energy beam irradiation high-pressure mercury lamp (manufactured by iGraphics, product name "H04-L41") at an illuminance of 230 mW / cm at a light wavelength of 365 nm. 2 , light intensity 700mJ / cm 2The transfer film was cured using an ultraviolet actinometer (UV Power Puck (registered trademark) II, manufactured by Heraus), and the peel strength of the cured transfer film from the optical film at 23°C and 50% RH was evaluated by the evaluation method described above. Furthermore, after curing, the optical film was peeled off from the transfer film and visually evaluated for cracks, fissures, falling off, etc. using the evaluation methods described above. The results are shown in Table 1.

[0127] (Comparative Example 1) A polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET50A-4360", thickness 50 μm) having an easy-adhesion layer on one side was used as the support film, and a transfer film having a pressure-sensitive adhesive layer (thickness: 10 μm) composed of a pressure-sensitive adhesive composition mixed with 100 parts by mass of a butyl acrylate resin (manufactured by Saiden Chemical Co., Ltd., LT-55) and 2 parts by mass of an isocyanate-based crosslinking agent (manufactured by Saiden Chemical Co., Ltd., Koukazai K-315) was laminated on the surface of the easy-adhesion layer of the PET film. A structure was obtained in the same manner as in Example 1, except that the transfer film was laminated to the optical film. The pressure-sensitive adhesive layer consisted of a re-peelable pressure-sensitive adhesive whose peel strength does not change due to physicochemical treatments such as temperature changes or energy beam irradiation. Using the obtained structure, the peel strength of the transfer film from the optical film at 23°C 50% RH before UV irradiation, the peel strength of the transfer film from the optical film at 23°C 50% RH after UV irradiation of the adhesive layer of a separately prepared structure with the same specifications, and the peel strength of the transfer film from the optical film at 10°C when a separately prepared structure with the same specifications was cooled to 10°C (held for 10 minutes) were each evaluated using the evaluation methods described above. Furthermore, the optical film peeled from the pressure-sensitive adhesive layer after UV irradiation was visually evaluated for cracks, fissures, falling off, etc., and the optical film peeled from the pressure-sensitive adhesive layer at 10° C. was visually evaluated for cracks, fissures, falling off, etc., using the evaluation method described above. The results are shown in Table 1.

[0128] [Table 1]

[0129] In Example 1, which used a temperature-sensitive adhesive layer, and in Example 2, which used an energy-ray-curable adhesive layer, the peel strength of each adhesive layer to the optical film was reduced, the optical film could be easily peeled from the transfer film, and no defects such as cracks, fissures, or falling off occurred on the peeled surface of the optical film after peeling. In contrast, in Comparative Example 1, the peel strength of the adhesive layer to the optical film was maintained high, the optical film could not be easily peeled from the adhesive layer on the process film, and defects such as cracks, fissures, or falling off occurred on the peeled surface of the optical film after peeling. [Industrial Applicability]

[0130] According to the composition of the present invention, after a thin optical film is bonded to a glass substrate or the like, it can be easily peeled off from the pressure-sensitive adhesive layer, and defects such as cracks, fissures, and falling off do not occur on the peeled surface of the optical film after peeling. Therefore, it is expected that the composition of the present invention will be applied to components such as optical films used in electronic devices such as display devices such as liquid crystal displays and organic electroluminescence (EL) displays, for example, anti-reflection hard coat films, polarizing plate protective films for polarizing plates used in liquid crystal displays, and further to ITO substrate films used in touch panels, etc. [Explanation of symbols]

[0131] 1: Construct 2: Support film 3: Adhesive layer 4: Transfer film 5: Optical film 6: Carrier film

Claims

1. A structure comprising a support film, a transfer film including a pressure-sensitive adhesive layer, and an optical film in contact with the pressure-sensitive adhesive layer, wherein a peel force of the transfer film from the optical film is reduced by a physicochemical treatment of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is a temperature-sensitive pressure-sensitive adhesive layer whose peel strength decreases with temperature change or an energy ray-curable pressure-sensitive adhesive layer whose peel strength decreases when cured by energy ray irradiation, the peel strength of the heat-sensitive adhesive layer from the optical film at 23°C and 50% RH is 2,000 mN / 50 mm or more and 10,000 mN / 50 mm or less, and the peel strength of the heat-sensitive adhesive layer from the optical film at 10°C is 10 mN / 50 mm or more and 250 mN / 50 mm or less; the peel strength of the energy ray-curable pressure-sensitive adhesive layer from the optical film at 23°C, 50% RH before curing is 2,000 mN / 50 mm or more and 10,000 mN / 50 mm or less, and the peel strength of the energy ray-curable pressure-sensitive adhesive layer from the optical film at 23°C, 50% RH after curing is 10 mN / 50 mm or more and 250 mN / 50 mm or less, The optical film has a thickness of 0.1 to 20 μm.

2. 2. The structure according to claim 1, wherein the optical film is a plastic film made of a cured product of a curable resin composition containing a polymer component and a curable monomer.

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