WO2025033340A1 - Adhesive film, adhesive film with release film, adhesive film for constituent member of flexible image display device, laminate for flexible image display device, and flexible image display device - Google Patents

Abstract

Provided is the following adhesive film excellent in heat resistance and capable of suppressing warpage of a laminate.　This adhesive film is formed from a resin composition containing (A) an epoxy resin having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, (B) a urethane resin, and (C) an epoxy resin curing agent, wherein the storage elastic modulus (E') at 100°C after curing is 1 × 10⁷ Pa or less.

Description

Adhesive film, adhesive film with release film, adhesive film for component of flexible image display device, laminate for flexible image display device, and flexible image display device

The present invention relates to an adhesive film, an adhesive film with a release film, an adhesive film for components of a flexible image display device, a laminate for a flexible image display device, and a flexible image display device.

In recent years, in the field of image display devices equipped with liquid crystal displays, organic EL displays, etc., development has been progressing on flexible image display devices, such as bendable displays having a curved image display surface, foldable displays that can be repeatedly bent, and rollable displays that can be rolled up.
In such an image display device, a plurality of component sheets, such as a surface protective film, a cover lens, a circular polarizing plate, a touch film sensor, and a light-emitting element, are laminated together with an adhesive layer to form a laminated structure, and each laminated structure can be regarded as a laminated sheet formed by laminating component sheets and adhesive layers.

Patent Document 1 discloses a laminate comprising a double-sided pressure-sensitive adhesive sheet having a glass transition temperature and storage modulus within a specified range, and a flexible member for an image display device, which does not break or peel even in a bending test approximating an actual usage environment.
However, although the double-sided pressure-sensitive adhesive sheet disclosed in Patent Document 1 has high bending resistance, it has a low elastic modulus and insufficient heat resistance.
In addition, when a liquid adhesive is used as the adhesive layer, it is usually necessary to cure the adhesive by active energy rays or heat. When image display device components are laminated via a liquid adhesive and the adhesive is cured, the adhesive is likely to overflow or have thickness variations, and there is a problem that the adhesive shrinks during curing and causes a large warp in the laminate.

International Publication No. 2018/173896

In light of this background, the present invention provides an adhesive film that has excellent heat resistance and can suppress warping of the laminate, an adhesive film with a release film, an adhesive film for components of a flexible image display device, a laminate for an image display device, and a flexible image display device.

In view of these circumstances, the present inventors have discovered that an adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), and an epoxy resin curing agent (C), and which has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less, has excellent heat resistance and excellent resistance to warping during curing.
The present inventors have also found that an adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, and a liquid epoxy compound (F) having a boiling point of 170°C or more at 1 atmospheric pressure (excluding the epoxy resin (A)), has excellent heat resistance and excellent warping resistance when cured.
Furthermore, the present inventors have discovered that an adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), an epoxy resin curing agent (C) and a liquid epoxy compound (d1) having an epoxy equivalent of 1,000 g/eq or less, and having a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less, has excellent heat resistance and excellent resistance to warping during curing.

That is, the present invention has the following aspects.
[1] An adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), and an epoxy resin curing agent (C), wherein the adhesive film has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less.
[2] The adhesive film according to [1], having a loss tangent (Tan δ) at 50° C. after curing of 0.1 or more.
[3] The adhesive film according to [1] or [2], wherein the resin composition further contains an epoxy compound (D) having an epoxy equivalent of 1,000 g/eq or less.
[4] The adhesive film according to [3], wherein the epoxy compound (D) contains a urethane-modified epoxy compound.
[5] The adhesive film according to any one of [1] to [4], wherein the content of the urethane resin (B) in the resin composition is 10 to 85 mass%.
[6] The adhesive film according to any one of [1] to [5], wherein the epoxy resin curing agent (C) contains an amine-based curing agent.
[7] The adhesive film according to any one of [1] to [6], wherein the urethane resin (B) has a storage modulus (E') at 20°C of 1 x ¹⁰⁷ Pa or less.
[8] An adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, and a liquid epoxy compound (F) having a boiling point of 170°C or more at 1 atmospheric pressure (excluding the epoxy resin (A)).
[9] The adhesive film according to [8], wherein the liquid epoxy compound (F) has an epoxy equivalent of 1,000 g/eq or less.
[10] The adhesive film according to [8] or [9], wherein the resin composition contains a solid epoxy compound (d2) having an epoxy equivalent of 1,000 g/eq or less.
[11] The adhesive film according to any one of [8] to [10], wherein the mass ratio [(A):(F)] of the epoxy resin (A) to the liquid epoxy compound (F) in the resin composition is 95:5 to 50:50.
[12] The adhesive film according to [10] or [11], wherein the mass ratio [(A):(d2)] of the epoxy resin (A) to the solid epoxy compound (d2) in the resin composition is 99:1 to 50:50.
[13] The adhesive film according to any one of [8] to [12], wherein the resin composition contains an epoxy resin curing agent (C).
[14] The adhesive film according to [13], wherein the epoxy resin curing agent (C) contains an amine-based curing agent.
[15] An adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), an epoxy resin curing agent (C), and a liquid epoxy compound (d1) having an epoxy equivalent of 1,000 g/eq or less, the adhesive film having a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less.
[16] The adhesive film according to [15], wherein the epoxy resin curing agent (C) contains an amine-based curing agent.
[17] The adhesive film according to any one of [1] to [16], wherein the resin composition has an epoxy equivalent of 400 to 50,000 g/eq.
[18] The adhesive film according to any one of [1] to [17], which has an exothermic peak in a temperature range of 120 to 220°C when subjected to differential scanning calorimetry (DSC) at a heating rate of 10°C/min, and the heat quantity of the exothermic peak is 5 J/g or more.
[19] The adhesive film according to any one of [1] to [18], wherein the glass transition temperature (Tg1) determined by differential scanning calorimetry (DSC) at a heating rate of 10° C./min is 0 to 120° C., and the temperature (T1) of the exothermic peak in the differential scanning calorimetry (DSC) and the glass transition temperature (Tg1) satisfy the relationship of the following formula:
T1-Tg1≧60
[20] The adhesive film according to any one of [1] to [19], having a solvent content of 10,000 ppm or less.
[21] The adhesive film according to any one of [1] to [20], having a total light transmittance of 80% or more and a haze of 5% or less.
[22] An adhesive film with a release film, comprising the adhesive film according to any one of [1] to [21] and a release film laminated thereon.
[23] An adhesive film for a component of a flexible image display device, comprising the adhesive film according to any one of [1] to [21].
[24] A laminate for a flexible image display device, comprising two image display device components laminated together via the adhesive film according to any one of [1] to [21].
[25] The laminate for a flexible image display device according to [24], having a curved portion or a bendable portion.
[26] A flexible image display comprising the laminate for a flexible image display according to [24] or [25].

The adhesive film of the present invention has excellent heat resistance and excellent resistance to warping when cured. Therefore, the adhesive film of the present invention can be suitably used as an adhesive film for image display devices.

An embodiment of the present invention will be described in detail below, although the present invention is not limited to the embodiment described below.
In the present invention, the term "film" conceptually includes a sheet, a film, and a tape.
Furthermore, when the term "panel" is used, such as an image display panel or a protective panel, it encompasses a plate, a sheet, and a film.

In this specification, when it is written "x to y" (x and y are arbitrary numbers), unless otherwise specified, it includes the meaning of "greater than x and less than y", as well as the meaning of "preferably greater than x" or "preferably smaller than y".
In addition, when it is stated that the amount is "x or more" (x is any number), it also means that the amount is "preferably greater than x" unless otherwise specified, and when it is stated that the amount is "y or less" (y is any number), it also means that the amount is "preferably smaller than y" unless otherwise specified.
Furthermore, "x and/or y (x and y are optional configurations)" means at least one of x and y, and means three possibilities: x only, y only, and x and y.
In this specification, the term "main component" means a component that has a significant effect on the properties of the target object, and the content of the component in the target object is usually 50 mass % or more, preferably 55 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more, and may be 100 mass %.
In the present specification, the upper limit or lower limit of a numerical range described in stages can be arbitrarily combined with the upper limit or lower limit of a numerical range of another stage. In addition, in the numerical range described in this specification, the upper limit or lower limit of the numerical range can be replaced with a value shown in the examples.

The adhesive film according to one embodiment of the present invention is a film in an A-stage or B-stage state.
The A-stage state, as defined in JIS K6900:1994, refers to an early stage in the preparation of a thermosetting resin in which the material is still soluble in certain liquids and is fusible.
The B-stage state, as defined in JIS K6900:1994, refers to an intermediate stage in which the material swells when in contact with a certain liquid and softens when heated, but does not completely dissolve or melt.
The adhesive film is usually applied to an adherend and heat-treated to completely cure (C-stage state) and exert its adhesive strength to the adherend.

An adhesive film according to one embodiment of the present invention is formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B) and an epoxy resin curing agent (C), and has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less (hereinafter, this film may be referred to as "this film 1", and the resin composition that forms this film 1 may be referred to as "resin composition 1").

An adhesive film according to another embodiment of the present invention is formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, and a liquid epoxy compound (F) having a boiling point of 170°C or more at 1 atmosphere (excluding the epoxy (A)) (hereinafter, this may be referred to as "this film 2", and the resin composition forming this film 2 may be referred to as "resin composition 2").

Furthermore, an adhesive film according to another embodiment of the present invention is formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), an epoxy resin curing agent (C), and a liquid epoxy compound (d1) having an epoxy equivalent of 1,000 g/eq or less, and has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less (hereinafter, this may be referred to as "this film 3", and the resin composition forming this film 3 may be referred to as "resin composition 3").

The present films 1 to 3 will now be described.
In this specification, the present films 1 to 3 may be collectively referred to simply as "the present film," and the resin compositions 1 to 3 may be collectively referred to simply as "the resin composition."

<<Present Film 1 (Resin Composition 1)>>
The resin composition 1 forming the present film 1 contains an epoxy resin (A) (hereinafter, sometimes referred to as "epoxy resin (A)") having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), and an epoxy resin curing agent (C).

[Epoxy resin (A)]
The epoxy resin (A) is preferably a thermosetting resin having an epoxy group, excluding the silane coupling agent (E) described below.

The number average molecular weight of the epoxy resin (A) used in the present film 1 is 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more, from the viewpoint of excellent heat resistance and suppression of warping of the laminate. The upper limit is usually 200,000, preferably 150,000, and more preferably 100,000, and is, for example, usually 10,000 to 200,000, preferably 20,000 to 150,000, and more preferably 20,000 to 100,000.
In the present invention, the number average molecular weight of the epoxy resin can be measured as a value converted into standard polystyrene by gel permeation chromatography (GPC).

The epoxy resin (A) has an epoxy equivalent of 5,000 g/eq or more, preferably 6,000 g/eq or more, more preferably 7,000 g/eq or more, and particularly preferably 7,500 g/eq or more, as measured according to JIS K7236, in order to have excellent heat resistance and suppress warping of the laminate. The upper limit is usually 100,000 g/eq, preferably 75,000 g/eq, and more preferably 50,000 g/eq, and is, for example, usually 5,000 to 100,000 g/eq, preferably 6,000 to 75,000 g/eq, and more preferably 7,000 to 50,000 g/eq.

Examples of the epoxy resin (A) include modified epoxy resins such as alcohol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol C type epoxy resins, bisphenol S type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, dicyclopentadiene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, urethane modified epoxy resins, rubber modified epoxy resins, and chelate modified epoxy resins. These may be used alone or in combination of two or more.

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

The content of the epoxy resin (A) in the resin composition 1 is usually 5% by mass, preferably 10% by mass or more, more preferably 30% by mass or more, and particularly preferably 55% by mass or more. The upper limit is usually 95% by mass, preferably 90% by mass, and is usually 5 to 95% by mass, and preferably 10 to 90% by mass.

[Urethane resin (B)]
The urethane resin (B) is a polymer having a urethane bond in the main chain. The urethane resin (B) may have a polyol-derived structural unit and a polyisocyanate-derived structural unit, and may further have a polycarboxylic acid-derived structural unit. The urethane resin (B) may be used alone or in combination of two or more kinds.
The present film 1 is formed from the resin composition 1 containing the urethane resin (B) having a low elastic modulus, and therefore has excellent resistance to warping when cured.

Examples of the polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

Examples of the polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, polytetramethylene ether glycol, and polyhexamethylene ether glycol.
Examples of the polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or acid anhydrides thereof, and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,7-dimethyl-2,3-dimethyl-2,4-dimethyl-2,5-dimethyl-2,6-dimethyl-2,7-dimethyl-2,8-dimethyl-2,9-dimethyl-2,10-dimethyl-2,11-dimethyl-2,12-dimethyl-2,13-dimethyl-2,14-dimethyl-2,15-dimethyl-2,16-dimethyl-2,17-dimethyl-2,18-dimethyl-2,21-dimethyl-2,22-dimethyl-2,23-dimethyl-2,24-dimethyl-2,25-dimethyl-2,3-dimethyl-2,3-dimethyl-2,26-dimethyl-2,3-dimethyl-2,27-dimethyl-2,3-dimethyl-2,3-dimethyl-2,3-dimethyl-2,4-dimethyl-2,17-dimethyl-2,18-dimethyl-2,21-dimethyl-2,22-dimethyl-2,3-dimethyl-2,19-dimethyl-2,23-dimethyl-2,24-dimethyl-2,25-dimethyl-2,3-dimethyl-2,26-dimethyl-2,27-dimethyl-2,3-dimethyl-2,27-dimethyl-2,28-dimethyl-2,3- diol, 2-methyl-2,4-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, benzenedimethanol, bishydroxyethoxybenzene, alkyldialkanolamines, lactonediols, etc.
Examples of the polycarbonate-based polyols include polycarbonate diols obtained by dealcoholization reaction of the polyhydric alcohols with dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, or the like, such as poly(1,6-hexylene) carbonate and poly(3-methyl-1,5-pentylene) carbonate.
Among these, polyester polyols are preferred.

Examples of the polyisocyanate include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and triazine diisocyanate; aliphatic diisocyanates having an aromatic ring such as α,α,α',α'-tetramethyl xylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate; and alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and isopropylidenedicyclohexyl diisocyanate. These may be used alone or in combination.

From the viewpoint of warpage resistance, the urethane resin (B) preferably has a storage modulus (E') at 20°C measured using a dynamic viscoelasticity measuring device of 1 x ¹⁰ Pa or less, more preferably 8 x ¹⁰ Pa or less, and particularly preferably 6 x ¹⁰ Pa or less. The lower limit is usually 1 x ¹⁰ Pa, preferably 1 x ¹⁰ Pa, and for example, usually 1 x ¹⁰ to 1 x ¹⁰ Pa, preferably 1 x ¹⁰ to 8 x ¹⁰ Pa.

The storage elastic modulus (E') can be determined by the following method.
A solution of the urethane resin (B) diluted with an organic solvent is applied onto a release film, heated at 120°C for 5 minutes, the organic solvent is dried, and the resulting film is cut into a size of 4 mm x 40 mm to prepare a measurement sample. This measurement sample is subjected to dynamic viscoelasticity measurement in accordance with JIS K7244-4:1999 using a viscoelasticity spectrometer "DVA-200 (manufactured by IT Measurement & Control Co., Ltd.)" in tension mode under conditions of a frequency of 1 Hz, a strain of 0.1%, a temperature range of -50 to 300°C, and a heating rate of 3°C/min, and the value of the storage tensile modulus (E') at 20°C is read.

The glass transition temperature (Tg) of the urethane resin (B) is preferably 0°C or lower from the viewpoint of warping resistance, more preferably -10°C or lower, even more preferably -20°C or lower, and particularly preferably -30°C or lower. The lower limit is usually -80°C, preferably -70°C, and particularly preferably -60°C, and is, for example, usually -80 to 0°C, preferably -60 to -10°C, and more preferably -60 to -20°C.

The glass transition temperature (Tg) can be determined by reading the maximum value of the loss tangent (Tan δ) from the temperature dispersion spectrum of the dynamic viscoelasticity obtained by measuring the storage tensile modulus (E').

The weight average molecular weight of the urethane resin (B) is not particularly limited, but is usually 5,000 to 500,000, and preferably 10,000 to 200,000.

The content of urethane resin (B) in the resin composition 1 is preferably 10 to 85% by mass, more preferably 15 to 70% by mass, even more preferably 18 to 65% by mass, particularly preferably 20 to 60% by mass, and especially preferably 25 to 55% by mass, from the viewpoint of warping resistance.

In addition, the mass ratio [(A):(B)] of the epoxy resin (A) to the urethane resin (B) in the resin composition 1 is preferably 95:5 to 10:90 from the viewpoint of warping resistance, more preferably 90:10 to 50:50, even more preferably 85:15 to 60:40, and particularly preferably 80:20 to 70:30.

[Epoxy resin curing agent (C)]
Examples of the epoxy resin curing agent (C) include polyfunctional phenol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, imidazole-based curing agents, amide-based curing agents, cationic polymerization-based curing agents, and organic phosphine-based curing agents. These may be used alone or in combination of two or more. Among these, from the viewpoint of curability, amine-based curing agents and imidazole-based curing agents are preferred, and amine-based curing agents are particularly preferred.

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

The amine-based curing agent may, for example, be aliphatic primary, secondary, or tertiary amines, aromatic primary, secondary, or tertiary amines, cyclic amines, guanidines, or urea derivatives. Specific examples include triethylenetetramine, polyoxypropylenediamine, diaminodiphenylmethane, diaminodiphenylether, metaxylenediamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, dimethylurea, or guanylurea. Among these, from the viewpoint of curing properties, aliphatic primary, secondary, or tertiary amines, or cyclic amines are preferred, and polyoxypropylenediamine is more preferred.

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

Examples of the imidazole-based curing agent include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and benzimidazole. Of these, 2-ethyl-4-methylimidazole is preferred.

Examples of the amide-based curing agent include dicyandiamide and its derivatives, polyamide resins, etc.

The cationic polymerization curing agent generates cations by heat or irradiation with active energy rays, and examples thereof include aromatic onium salts, etc. Specific examples thereof include compounds consisting of an anion component such as _SbF6- ^, _BF4- ^, _{AsF6- , PF6-} ^{, CF3SO3-} , B( ^C6F5 ) _{4- ,} ^etc. , and an aromatic cation component containing an atom such as iodine, sulfur _, nitrogen, or phosphorus _.

Examples of the organic phosphine curing agent include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine, etc.; phosphonium salts such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate.

The content of the epoxy resin curing agent (C) is usually 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, per 100 parts by mass of the epoxy components (the total of the epoxy resin (A) and the epoxy compound (D) having an epoxy equivalent of 1,000 g/eq or less, described below) contained in the resin composition 1.

[Epoxy compound (D) having an epoxy equivalent of 1,000 g/eq or less]
From the viewpoint of heat resistance, the resin composition 1 forming the present film 1 preferably contains, in addition to the epoxy resin (A), an epoxy compound (D) having an epoxy equivalent of 1,000 g/eq or less [hereinafter, sometimes referred to as "epoxy compound (D)]. The epoxy compound (D) does not include the silane coupling agent (E) described below, that is, an organosilicon compound having one or more reactive functional groups and one or more alkoxy groups bonded to silicon atoms in the structure. The epoxy compound (D) can be used alone or in combination of two or more kinds.

The epoxy compound (D) preferably has an epoxy equivalent of 1,000 g/eq or less, as measured according to JIS K7236, from the viewpoint of curability, more preferably 800 g/eq or less, particularly preferably 500 g/eq or less, and even more preferably 300 g/eq or less. The lower limit is usually 50 g/eq, preferably 100 g/eq, for example, usually 50 to 1,000 g/eq, preferably 100 to 800 g/eq. If the epoxy equivalent of the epoxy compound (D) exceeds 1,000 g/eq, the adhesive strength of the film tends to decrease.

The epoxy compound (D) may be a liquid epoxy compound (d1) or a solid epoxy compound (d2). Among them, the liquid epoxy compound (d1) is preferred from the viewpoint of reducing the content of volatile substances contained in the present film, and the solid epoxy compound (d2) is preferred from the viewpoint of heat resistance.
In this specification, the term "liquid" refers to a state in which the material has fluidity at 25°C, and specifically refers to a material having a viscosity, as measured with a B-type viscometer, of usually 1,000,000 mPa·s or less, preferably 100,000 mPa·s or less, more preferably 10,000 mPa·s or less, even more preferably 5,000 mPa·s or less, particularly preferably 1,000 mPa·s or less, and most preferably 100 mPa·s or less.
In addition, in this specification, the term "solid" refers to a solid state at 25°C, and specifically refers to a softening point of usually 30°C or higher, preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher.

The liquid epoxy compound (d1) is what is called a reactive diluent. By using this liquid epoxy compound (d1), volatile substances such as solvents can be efficiently removed during heating when forming the present film.
Examples of the liquid epoxy compound (d1) include monofunctional aliphatic epoxy compounds such as ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxytetradecane, and lauryl glycidyl ether; monofunctional aromatic epoxy compounds such as o-phenylphenol glycidyl ether, phenyl glycidyl ether, 2-biphenylyl glycidyl ether, and 4-t-butylphenyl glycidyl ether; monofunctional epoxy compounds such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, and 1,4-butane Examples of the epoxy compounds include bifunctional aliphatic epoxy compounds such as diol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and dimer acid diglycidyl ester, bifunctional alicyclic epoxy compounds such as 1,4-cyclohexanedimethanol diglycidyl ether and hydrogenated bisphenol A diglycidyl ether, and bifunctional aromatic epoxy compounds such as cresyl glycidyl ether; trifunctional epoxy compounds such as trifunctional aliphatic epoxy compounds such as trimethylolpropane triglycidyl ether, and modified epoxy compounds such as urethane-modified epoxy compounds, rubber-modified epoxy compounds, and chelate-modified epoxy compounds. The liquid epoxy compound (d1) can be used alone or in combination of two or more. Among them, urethane-modified epoxy compounds are preferred in terms of heat resistance and warpage resistance.

Examples of the solid epoxy compound (d2) include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol C type epoxy compounds, bisphenol S type epoxy compounds, naphthalene type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, bisphenol A novolac type epoxy compounds, triphenylmethane type epoxy compounds, dicyclopentadiene type epoxy compounds, polyfunctional phenol type epoxy compounds, etc. These may be used alone or in combination of two or more. The solid epoxy compound (d2) may be used alone or in combination of two or more. Among them, bisphenol A novolac type epoxy compounds are preferred in terms of heat resistance.

Commercially available solid epoxy compounds (d2) include, but are not limited to, jER154, jER157S70, jER157S65, jER1031S, jER1032H60, jER6810, jERYX7700, jERYX8800, jERYX7760, jERYX4000, jERYX4000H, jERYX4000HS, jERYL6121HA, and jERYL6677 (all trade names, manufactured by Mitsubishi Chemical Corporation).

The number average molecular weight of the epoxy compound (D) is usually 250 or more, preferably 300 or more, more preferably 350 or more, and particularly preferably 370 or more, in order to provide excellent heat resistance and suppress warping of the laminate. The upper limit is usually 10,000, preferably 7,000, and more preferably 5,000, and is, for example, usually 250 to 10,000, preferably 300 to 7,000, and more preferably 350 to 5,000.

When the resin composition 1 contains an epoxy compound (D), the content is usually 80% by mass or less, preferably 70% by mass or less, and particularly preferably 60% by mass or less. The lower limit is usually 0.1% by mass, preferably 1% by mass, and is, for example, usually 0.1 to 80% by mass, preferably 1 to 70% by mass.

When the resin composition 1 contains a liquid epoxy compound (d1), the content is usually 80% by mass or less, preferably 70% by mass or less, and particularly preferably 60% by mass or less. The lower limit is usually 0.1% by mass, preferably 1% by mass, and is, for example, usually 0.1 to 80% by mass, preferably 1 to 70% by mass.

When the resin composition 1 contains a solid epoxy compound (d2), the content is usually 30% by mass or less, preferably 20% by mass or less, and particularly preferably 10% by mass or less. The lower limit is usually 0.1% by mass, preferably 1% by mass, and is, for example, usually 0.1 to 30% by mass, preferably 1 to 20% by mass.

In addition, the mass ratio [(A):(D)] of the epoxy resin (A) to the epoxy compound (D) in the resin composition 1 is preferably 99:1 to 1:99 from the viewpoint of heat resistance, more preferably 98:2 to 5:95, and particularly preferably 97:3 to 10:90.

The mass ratio [(A):(d1)] of the epoxy resin (A) to the liquid epoxy compound (d1) in the resin composition 1 is preferably 80:20 to 1:99 from the viewpoint of heat resistance, more preferably 75:25 to 5:95, and particularly preferably 70:30 to 10:90.

The mass ratio [(A):(d2)] of the epoxy resin (A) to the solid epoxy compound (d2) in the resin composition 1 is preferably 99:1 to 50:50 from the viewpoint of heat resistance, more preferably 98:2 to 55:45, and particularly preferably 97:3 to 85:15.

<Silane Coupling Agent (E)>
The resin composition 1 preferably contains a silane coupling agent (E).
Said silane coupling agent (E) is an organic silicon compound that contains reactive functional group and alkoxy group bonded with silicon atom in its structure.Said reactive functional group can be, for example, epoxy group, (meth)acryloyl group, mercapto group, hydroxyl group, carboxyl group, amino group, amide group, isocyanate group, among which, epoxy group and mercapto group are preferred from the viewpoint of durability balance.

The alkoxy group bonded to the silicon atom preferably contains an alkoxy group having 1 to 8 carbon atoms from the viewpoint of durability and storage stability, and is particularly preferably a methoxy group or an ethoxy group. The silane coupling agent may also have an organic substituent other than the reactive functional group and the alkoxy group bonded to the silicon atom, such as an alkyl group or a phenyl group.

Specific examples of the silane coupling agent (E) include monomer-type epoxy group-containing silane coupling agents which are silane compounds such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and silane coupling agents which are partially hydrolyzed and condensed to polymerize with the silane compounds or which are combined with methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxy ... oligomer-type epoxy group-containing silane coupling agents which are silane compounds obtained by co-condensation of alkyl group-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, 3-mercaptopropylmethyldimethoxysilane, and monomer-type mercapto group-containing silane compounds such as silane compounds obtained by hydrolysis and condensation polymerization of a part of the silane compounds, or methyltriethoxysilane, ethyltriethoxysilane, oligomeric mercapto group-containing silane coupling agents which are silane compounds obtained by co-condensation of alkyl group-containing silane compounds such as methyltrimethoxysilane and ethyltrimethoxysilane; (meth)acryloyl group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane and 3-acryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; Examples of the silane coupling agent include amino group-containing silane coupling agents such as silane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane. The silane coupling agent (E) may be used alone or in combination of two or more.
Among these, from the viewpoint of excellent durability, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferably used, and among these, epoxy group-containing silane coupling agents are preferred.

When the resin composition 1 contains a silane coupling agent (E), the content thereof is usually 0.005 to 10 parts by mass, preferably 0.01 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the epoxy components (e.g., the total of the epoxy resin (A) and the epoxy compound (D)) contained in the resin composition 1. When the content of the silane coupling agent (E) is within the above range, durability tends to be improved.

[Other ingredients]
The resin composition 1 may contain other components as necessary within a range that does not impair the effects of the present invention (for example, usually 10% by mass or less, preferably 5% by mass or less of the resin composition 1), such as resins other than epoxy resins, sensitizers, crosslinking agents, ultraviolet absorbers, polymerization inhibitors, fillers, antioxidants, leveling agents, slipping agents, fine particles, dispersants, organic peroxides, reducing agents, radical polymerizable compounds, plasticizers, antifoaming agents, polymerization initiators, elastomers, etc. These may be used alone or in combination of two or more.
For example, when an elastomer is blended, it tends to be possible to adjust the flexibility and impact resistance of the cured film 1. Furthermore, when a polymerization initiator such as a thermal polymerization initiator, e.g., a peroxide or an azo compound, or a photopolymerization initiator is blended, it tends to be possible to adjust the strength of the cured film 1.

The resin composition 1 is obtained by uniformly mixing the epoxy resin (A), the urethane resin (B), the epoxy resin curing agent (C), preferably the epoxy compound (D), and other components as necessary, in a conventional manner.

The types and skeletons of the epoxy resin (A) and epoxy compound (D) contained in the resin composition 1 can be confirmed by, for example, NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscope) analysis, ICP (inductively coupled plasma) optical emission spectroscopy, TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), and various types of chromatography.

In terms of heat resistance and warping resistance, the epoxy equivalent of the resin composition 1, measured according to JIS K7236, is preferably 400 to 50,000 g/eq, more preferably 1,000 to 30,000 g/eq, and particularly preferably 2,000 to 20,000 g/eq.

<<Present Film 2 (Resin Composition 2)>>
The resin composition 2 forming the present film 2 contains an epoxy resin (A) and a liquid epoxy compound (F) (excluding the epoxy resin (A)) having a boiling point of 170° C. or higher at 1 atmospheric pressure.

[Epoxy resin (A)]
The epoxy resin (A) may be the epoxy resin (A) described in the resin composition 1, and the preferred type, physical properties, content, and the like are also the same as those described in the resin composition 1.

[Liquid epoxy compound (F) having a boiling point of 170° C. or higher at 1 atmospheric pressure]
The liquid epoxy compound (F) having a boiling point of 170°C or higher at 1 atmospheric pressure (hereinafter, may be referred to as "liquid epoxy compound (F)") is other than the epoxy resin (A), and the present film 2 is formed from a resin composition 2 containing the liquid epoxy compound (F), and therefore has excellent heat resistance and excellent warping resistance when cured. The liquid epoxy compound (F) is other than the silane coupling agent (E).
The liquid epoxy compound (F) is what is called a reactive diluent, and the resin composition 2 forming the present film 2 contains this liquid epoxy compound (F), which makes it possible to efficiently remove volatile substances such as solvents during heating when forming the film, thereby reducing the content of volatile substances contained in the present film 2. Therefore, the present film 2 can be prevented from warping when cured by heat treatment.

The boiling point of the liquid epoxy compound (F) is 170° C. or higher, preferably 175° C. or higher, more preferably 180° C. or higher, and particularly preferably 185° C. or higher, from the viewpoint of heat resistance. The upper limit is not particularly limited, but is usually 250° C. or lower, preferably 220° C. or lower, for example, usually 170 to 250° C., preferably 175 to 220° C.
In this specification, the boiling point is a value at 1 atmospheric pressure. If the boiling point at 1 atmospheric pressure cannot be measured, a converted boiling point to 1 atmospheric pressure using a boiling point conversion chart can be used.

The number average molecular weight of the liquid epoxy compound (F) is usually 1,000 or less, more preferably 500 or less, and particularly preferably 300 or less, in order to suppress warping of the laminate. The lower limit is usually 100, and is usually from 100 to 1,000, for example.

In order to suppress warping of the laminate, the liquid epoxy compound (F) preferably has an epoxy equivalent measured according to JIS K7236 of 1,000 g/eq or less, more preferably 600 g/eq or less, even more preferably 400 g/eq or less, and particularly preferably 200 g/eq or less. The lower limit is preferably 50 g/eq, more preferably 100 g/eq, and is, for example, preferably 50 to 1,000 g/eq, more preferably 100 to 600 g/eq.

Examples of such liquid epoxy compounds (F) include monofunctional aliphatic epoxy compounds such as ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxytetradecane, and lauryl glycidyl ether; and monofunctional aromatic epoxy compounds such as o-phenylphenol glycidyl ether, phenyl glycidyl ether, 2-biphenylyl glycidyl ether, and 4-t-butylphenyl glycidyl ether.
bifunctional epoxy compounds such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dimer acid diglycidyl ester, and other bifunctional aliphatic epoxy compounds; bifunctional alicyclic epoxy compounds such as 1,4-cyclohexanedimethanol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and other bifunctional aromatic epoxy compounds such as cresyl glycidyl ether;
Examples of the epoxy compounds include trifunctional aliphatic epoxy compounds such as trimethylolpropane triglycidyl ether. These may be used alone or in combination of two or more. Among these, from the viewpoint of warping resistance, monofunctional epoxy compounds are preferred, monofunctional aliphatic epoxy compounds are more preferred, and 2-ethylhexyl glycidyl ether is particularly preferred.

The content of the liquid epoxy compound (F) in the resin composition 2 is usually 1 to 80 mass%, preferably 5 to 60 mass%, and particularly preferably 10 to 40 mass%.

The mass ratio [(A):(F)] of the epoxy resin (A) to the liquid epoxy compound (F) in the resin composition 2 is preferably 95:5 to 50:50 from the viewpoint of warping resistance, more preferably 90:10 to 60:40, and particularly preferably 85:15 to 70:30.

[Solid epoxy compound (d2)]
From the viewpoint of heat resistance, the resin composition 2 forming the present film 2 preferably contains, in addition to the epoxy resin (A) and the liquid epoxy compound (F), the solid epoxy compound (d2) described in the resin composition 1. The preferred types and physical properties of the solid epoxy compound (d2) are as described in the resin composition 1. As described above, the solid epoxy compound (d2) is one other than the silane coupling agent (E).

When the resin composition 2 contains a solid epoxy compound (d2), the content is usually 30% by mass or less, preferably 20% by mass or less, and particularly preferably 10% by mass or less. The lower limit is usually 0.1% by mass, preferably 1% by mass, and is, for example, usually 0.1 to 30% by mass, preferably 1 to 20% by mass.

In addition, the mass ratio [(A):(d2)] of the epoxy resin (A) to the solid epoxy compound (d2) in the resin composition 2 is preferably 99:1 to 50:50 from the viewpoint of warping resistance, more preferably 97:3 to 70:30, and particularly preferably 95:5 to 80:20.

[Epoxy resin curing agent (C)]
The resin composition 2 preferably contains an epoxy resin curing agent (C).
The preferred type, physical properties, etc. of the epoxy resin curing agent (C) are as described in the resin composition 1 above.

When the epoxy resin curing agent (C) is used, its content is usually 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, per 100 parts by mass of the epoxy components contained in the resin composition 2 [for example, the total of the epoxy resin (A), the liquid epoxy compound (F), and the epoxy compound (d2)].

[Silane coupling agent (E)]
The resin composition 2 preferably contains a silane coupling agent (E).
The preferred type, physical properties, content, etc. of the silane coupling agent (E) are as described in the resin composition 1 above.

[Other ingredients]
The resin composition 2 may contain other components as necessary within a range that does not impair the effects of the present invention (for example, usually 10% by mass or less, preferably 5% by mass or less of the resin composition 2), such as resins other than epoxy resins, sensitizers, crosslinking agents, ultraviolet absorbers, polymerization inhibitors, fillers, antioxidants, leveling agents, slipping agents, fine particles, dispersants, organic peroxides, reducing agents, radical polymerizable compounds, plasticizers, antifoaming agents, polymerization initiators, elastomers, etc. These may be used alone or in combination of two or more.
For example, when an elastomer is blended, the flexibility and impact resistance of the film when cured tend to be adjustable. Also, when a polymerization initiator such as a thermal polymerization initiator, e.g., a peroxide or an azo compound, or a photopolymerization initiator is blended, the strength of the film when cured tends to be adjustable.

The resin composition 2 is obtained by uniformly mixing the epoxy resin (A), the liquid epoxy compound (F), preferably the solid epoxy compound (d2), the epoxy resin hardener (C), and other components as necessary, in a conventional manner.

The types and skeletons of the epoxy resin (A), liquid epoxy compound (F), and solid epoxy compound (d2) contained in the resin composition 2 can be confirmed by, for example, NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscope) analysis, ICP (inductively coupled plasma) optical emission spectroscopy, TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), and various types of chromatography.

In terms of heat resistance and warping resistance, the epoxy equivalent of the resin composition 2, as measured according to JIS K7236, is preferably 400 to 50,000, more preferably 500 to 10,000 g/eq, even more preferably 600 to 8,000 g/eq, and particularly preferably 800 to 6,000 g/eq.

<<Present Film 3 (Resin Composition 3)>>
The resin composition 3 forming the present film 3 contains an epoxy resin (A), a urethane resin (B), an epoxy resin curing agent (C), and a liquid epoxy compound (d1).
Since the present film 3 is formed from the resin composition 3 containing the urethane resin (B) having a low elastic modulus, it has excellent resistance to warping when cured by heat treatment.
In addition, since the present film 3 is formed from the resin composition 3 containing the liquid epoxy compound (d1), volatile substances such as solvents can be efficiently removed during heating when forming the film, and the content of volatile substances contained in the present film 3 can be reduced. Therefore, the present film 3 has excellent warping resistance when cured by heat treatment.

[Epoxy resin (A)]
The epoxy resin (A) may be the epoxy resin (A) described in the resin composition 1, and the preferred types, physical properties, and the like are also the same as those described in the resin composition 1.

The content of the epoxy resin (A) in the resin composition 3 is usually 1% by mass, preferably 3% by mass or more, more preferably 5% by mass or more, and particularly preferably 7% by mass or more. The upper limit is usually 70% by mass, preferably 60% by mass, more preferably 50% by mass, and is usually 1 to 70% by mass, preferably 3 to 60% by mass, and more preferably 5 to 50% by mass.

[Urethane resin (B)]
The urethane resin (B) may be the urethane resin (B) described in the resin composition 1, and the preferred types, physical properties, and the like are also the same as those described in the resin composition 1.

The content of urethane resin (B) in the resin composition 3 is preferably 10 to 85% by mass, more preferably 15 to 70% by mass, even more preferably 18 to 65% by mass, particularly preferably 20 to 60% by mass, and especially preferably 25 to 55% by mass, from the viewpoint of warping resistance.

In addition, the mass ratio [(A):(B)] of the epoxy resin (A) to the urethane resin (B) in the resin composition 3 is preferably 70:30 to 1:99 from the viewpoint of warping resistance, more preferably 65:35 to 5:95, even more preferably 60:40 to 10:90, and particularly preferably 50:50 to 15:85.

[Epoxy resin curing agent (C)]
The epoxy resin curing agent (C) may be the epoxy resin curing agent (C) described in the resin composition 1, and the preferred types, physical properties, etc. are as described in the resin composition 1.

The content of the epoxy resin hardener (C) is usually 0.001 to 20 parts by mass, preferably 0.01 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass, per 100 parts by mass of the epoxy components contained in the resin composition 3 [e.g., the total of the epoxy resin (A) and the liquid epoxy compound (d1)].

[Liquid epoxy compound (d1)]
The liquid epoxy compound (d1) may be the liquid epoxy compound (d1) described in the resin composition 1, and the preferred type, physical properties, content, etc. are as described in the resin composition 1.

[Solid epoxy compound (d2)]
From the viewpoint of heat resistance, the resin composition 3 forming the present film 3 preferably contains the solid epoxy compound (d2) described in the resin composition 1. The preferred type, physical properties, content, etc. of the solid epoxy compound (d2) are as described in the resin composition 1. As described above, the solid epoxy compound (d2) is one excluding the silane coupling agent (E).

[Silane coupling agent (E)]
The resin composition 3 preferably contains a silane coupling agent (E).
The preferred type, physical properties, content, etc. of the silane coupling agent (E) are as described in the resin composition 1 above.

[Other ingredients]
The resin composition 3 may contain other components as necessary within a range that does not impair the effects of the present invention (for example, usually 10% by mass or less, preferably 5% by mass or less of the resin composition 3), such as resins other than epoxy resins, sensitizers, crosslinking agents, ultraviolet absorbers, polymerization inhibitors, fillers, antioxidants, leveling agents, slipping agents, fine particles, dispersants, organic peroxides, reducing agents, radical polymerizable compounds, plasticizers, antifoaming agents, polymerization initiators, elastomers, etc. These may be used alone or in combination of two or more.
For example, when an elastomer is blended, the flexibility and impact resistance of the film when cured tend to be adjustable. Also, when a polymerization initiator such as a thermal polymerization initiator, e.g., a peroxide or an azo compound, or a photopolymerization initiator is blended, the strength of the film when cured tends to be adjustable.

The resin composition 3 is obtained by uniformly mixing the epoxy resin (A), the urethane resin (B), the epoxy resin curing agent (C), and the liquid epoxy compound (d1), and other components as necessary, in a conventional manner.

The types and skeletons of the epoxy resin (A), urethane resin (B), and liquid epoxy compound (d1) contained in the resin composition 3 can be confirmed by, for example, NMR (nuclear magnetic resonance spectroscopy), IR (infrared spectroscopy), SEM (scanning electron microscope) analysis, ICP (inductively coupled plasma) optical emission spectroscopy, TGA (thermogravimetric analysis), DSC (differential scanning calorimetry), and various types of chromatography.

In terms of heat resistance and warping resistance, the resin composition 3 preferably has an epoxy equivalent measured according to JIS K7236 of 400 to 50,000 g/eq, more preferably 600 to 10,000 g/eq, and particularly preferably 800 to 8,000 g/eq.

<Manufacturing method of the present film>
The method for producing the present film is not particularly limited, and for example, the resin composition may be formed into a sheet, which may then be heated to semi-cure (primary curing).

When the resin composition is formed into a sheet, a solvent (G) may be added to the resin composition to improve the handling properties of the resin composition.

[Solvent (G)]
Examples of the solvent (G) include organic solvents such as aromatic solvents, alcohol solvents, ester solvents, ketone solvents, glycol ether solvents, glycol ester solvents, chlorine solvents, ether solvents, and amide solvents. These may be used alone or in combination of two or more. Among these, ketone solvents, aromatic solvents, and ester solvents are preferred.

Examples of the aromatic solvent include benzene, toluene, and xylene, and among these, toluene is preferable.
The alcohol solvent includes lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, and isopropyl alcohol.
Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, 2-octanone, cyclopentanone, cyclohexanone, and acetylacetone. Of these, methyl ethyl ketone is preferable.
Examples of the glycol ether solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol mono-n-butyl ether, and propylene glycol monomethyl ether acetate.
Examples of the amide solvent include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, 2-pyrrolidone, and N-methylpyrrolidone.

When the solvent (G) is used, it is preferably used so that the concentration of the resin composition is 10 to 90% by mass, and more preferably 20 to 80% by mass. If the content of solvent (G) is too low, handling properties tend to decrease, and if the content of solvent (G) is too high, the amount of residual solvent when the film is formed increases, and the film tends to warp easily after curing.

The method for forming the resin composition into a sheet is not particularly limited, and examples include a method in which the resin composition is applied onto a release film or a component of an image display device to be described later to form a sheet, and a method in which the resin composition is extruded using a die such as a T-die and formed into a sheet using a cast roll or the like.

The coating method may be a known method, such as a comma coating method, a gravure coating method, a reverse coating method, a knife coating method, a dip coating method, a spray coating method, an air knife coating method, a spin coating method, a roll coating method, a printing method, a slide coating method, a curtain coating method, a die coating method, a casting method, a bar coating method, or an extrusion coating method.

The resin composition formed into a sheet is then semi-cured (primary cured) by heating.
The heating conditions for the semi-curing (primary curing) are appropriately adjusted depending on the components and amounts in the resin composition, but are usually 60 to 180° C. and 1 to 180 minutes. From the viewpoint of reducing poor curing, it is preferable to carry out a two-stage treatment in which primary heating is carried out at 60 to 100° C. for 1 to 30 minutes, and then secondary heating is carried out at 100 to 180° C., which is 40 to 80° C. higher than the primary heating temperature, for 1 to 150 minutes.

The thickness of the film thus obtained is usually 1 to 1,000 μm, preferably 2 to 200 μm, and particularly preferably 5 to 50 μm.
When the thickness of the present film is within the above range, the film tends to have suitable handleability.

After this film is applied to the adherend, it is heated to completely harden (C-stage state) and exert its adhesive strength on the adherend.

The temperature of the heat treatment is preferably 120°C or higher, more preferably 150°C or higher, even more preferably 160°C or higher, and particularly preferably 170°C or higher. However, if the heating temperature is too high, the adhesive properties and reliability may decrease due to decomposition and oxidative deterioration of the epoxy components. Therefore, the upper limit of the heating temperature is usually 250°C, and preferably 220°C.

The duration of the heat treatment is not particularly limited as long as it is a time sufficient for the curing reaction of the resin composition constituting the present film to proceed sufficiently, but is usually from 5 minutes to 200 hours, preferably from 10 minutes to 150 hours.
The heat treatment may be carried out under reduced pressure.

The film after the heat treatment (the cured film) is preferably subjected to a cooling treatment.
From the viewpoint of productivity, the cooling treatment is preferably performed at a cooling rate of 0.1° C./min or more, more preferably 0.5° C./min or more, and even more preferably 1° C./min or more.
On the other hand, from the viewpoint of reducing adhesion loss, uneven adhesion, uneven appearance, warping, and the like caused by cooling distortion inside the component or film, the cooling rate is preferably 40° C./min or less, more preferably 30° C./min or less, and even more preferably 20° C./min or less.

The number average molecular weight and epoxy equivalent of the epoxy resin (A), epoxy compound (D), liquid epoxy compound (F), etc. contained in this film can be substituted by extracting the sol content from this film and measuring the number average molecular weight and epoxy equivalent of the epoxy resin (A), epoxy compound (D), liquid epoxy compound (F), etc. in the sol content.

<Physical properties of this film>
The film may have the following physical properties:

In terms of warp resistance, the storage modulus (E') of the present film 1 or 3 at 100°C, measured by using a dynamic viscoelasticity measuring device after curing, is 1 x ¹⁰⁷ Pa or less, preferably 6 x ¹⁰⁶ Pa or less, and particularly preferably 4 x ¹⁰⁶ Pa or less. The lower limit is usually 1 x ¹⁰⁴ Pa, preferably 1 x ¹⁰⁵ Pa, and for example, usually 1 x ¹⁰⁴ to 1 x ¹⁰⁷ Pa, preferably 1 x ¹⁰⁵ to 6 x ¹⁰⁶ Pa.

The storage modulus (E') at 100°C can be determined by cutting the film after curing, which has been heat-treated at 170°C for 30 minutes, into a measurement sample of 4 mm x 40 mm, and measuring this sample in accordance with JIS K7244-4:1999 using a viscoelasticity spectrometer "DVA-200 (manufactured by IT Measurement & Control Co., Ltd.)" in tension mode under conditions of a frequency of 1 Hz, a strain of 0.1%, a temperature range of -50 to 300°C, and a heating rate of 3°C/min, and reading the value of the storage modulus (E') at 100°C.

In addition, in terms of heat resistance and warpage resistance, the loss tangent (Tan δ) of the cured film 1 or 3 at 50°C measured using a dynamic viscoelasticity measuring device is preferably 5.0 x ^10-2 or more, more preferably 1.0 x ^10-1 or more, and particularly preferably 5.0 x ^10-1 or more. The upper limit is usually 1.0 x ¹⁰² , preferably 1.0 x ¹⁰¹ , for example, usually 5.0 x ^10-2 to 1.0 x ¹⁰² , preferably 1.0 x ^10-1 to 1.0 x ¹⁰¹ .

The loss tangent (Tan δ) at 50°C can be determined by cutting the film after curing, which has been heat-treated at 170°C for 30 minutes, into a measurement sample of 4 mm x 40 mm, and measuring this measurement sample in accordance with JIS K7244-4:1999 using a viscoelasticity spectrometer "DVA-200 (manufactured by IT Measurement & Control Co., Ltd.)" in tensile mode under conditions of a frequency of 1 Hz, a strain of 0.1%, a temperature range of -50 to 300°C, and a heating rate of 3°C/min, and reading the value of the loss tangent (Tan δ) at 50°C.

When the present film is subjected to differential scanning calorimetry (DSC) at a heating rate of 10°C/min, it preferably has an exothermic peak in the temperature range of 120 to 220°C, more preferably 130 to 200°C, and particularly preferably 140 to 190°C.
The heat quantity of the exothermic peak is preferably 5 J/g or more, more preferably 10 J/g or more, and particularly preferably 15 J/g or more, with the upper limit usually being 100 J/g.
Since the present film has an exothermic peak with a specific amount of heat in the above temperature range, the film tends to have excellent heat resistance and warping resistance.

The present film preferably has a glass transition temperature (Tg1) of -40 to 120°C, more preferably 0 to 110°C, and particularly preferably 20 to 100°C, as determined by DSC at a heating rate of 10°C/min.
It is also preferable that the temperature (T1) of the exothermic peak determined by the DSC and the glass transition temperature (Tg1) satisfy the following relationship:
T1-Tg1≧60
In addition, in the present film, the difference between the exothermic peak temperature (T1) and the glass transition temperature (Tg1) is preferably 60° C. or more, more preferably 65° C. or more, and particularly preferably 80° C. or more, and is usually preferably 250° C. or less, more preferably 230° C. or less.
In particular, in the present film 1 or 3, the difference between the exothermic peak temperature (T1) and the glass transition temperature (Tg1) is preferably 80° C. or more, more preferably 90° C. or more, and particularly preferably 95° C. or more. The upper limit is usually 250° C., and preferably 230° C.
Furthermore, in the present film 2, the difference between the exothermic peak temperature (T1) and the glass transition temperature (Tg1) is preferably 65° C. or more, more preferably 70° C. or more, and particularly preferably 75° C. or more. The upper limit is usually 140° C., and preferably 130° C.
When the difference between the exothermic peak temperature (T1) and the glass transition temperature (Tg1) of the present film is within the above range, the film tends to have excellent heat resistance and warp resistance.

From the viewpoint of warping resistance, the present film preferably has a solvent content, as detected by gas chromatography, of 10,000 ppm or less, and more preferably 1,000 ppm or less.
The method for analyzing the amount of the residual solvent by gas chromatography is as described in the Examples.

The present film preferably has a total light transmittance of 80% or more, more preferably 85% or more, and further preferably 88% or more.
The total light transmittance is measured in accordance with JIS K7361-1.

The present film preferably has a haze of 5% or less, more preferably 3% or less, and even more preferably 1% or less.
When the haze of the present film is within the above range, it can be suitably used for flexible image display devices.
The haze is measured in accordance with JIS K7136.

This film has little warping after curing, and is preferably bonded to an adherend having an area of 70 to 100 ^cm2 under heat and pressure, and after the film has been thermally cured, the adherend is placed face down on a horizontal plate, and the average floating height of the four corners is 10 mm or less.
The adherend may be a resin sheet or glass, which is a main component of a flexible image display device component described later, etc. The thickness of the adherend is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

The adhesive strength of the cured film to an adherend is usually 2 N/cm or more, preferably 5 N/cm or more, and particularly preferably 8 N/cm or more. The adhesive strength can be determined by the following method.
A transparent polyimide (CPI) film (thickness 50 μm) cut to a width of 25 mm and a length of 150 mm is pressed onto the surface of this film pressed onto the chemically strengthened glass at a press pressure of 0.1 MPa and a temperature of 170° C. for 10 minutes under reduced pressure to obtain a sample for measuring adhesion.
After the adhesive strength measurement sample is fixed to a jig, an end of the test piece is fixed to the chuck of a testing machine, and the adhesive film is peeled off from the adherend at a peel angle of 90° and a peel speed of 50 mm/min. The peel strength is measured with a load cell and regarded as the adhesive strength.

<Adhesive film with release film>
From the viewpoint of handling, the present film is preferably an adhesive film with a release film. That is, the adhesive film with a release film according to one embodiment of the present invention has a structure in which a release film is laminated on the outermost surface of the present film. The release film is peeled off and removed when the present film is attached to an adherend.
The release film may be laminated only on the outermost surface of one side of the present film, or on both surfaces of the present film. From the viewpoint of ease of production process, however, a configuration in which the release film is laminated on the outermost surface of one side is preferred.

The thickness of the release film is usually 1 to 500 μm, preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 20 to 150 μm. If the film contains multiple release films, it is preferable that the thickness of each layer is within the above range. The thickness (average thickness) of the release film is measured with a micrometer and calculated as the arithmetic average.

The base material of the release film may be a thin film made of paper, resin, metal, etc. Furthermore, the release film may be a single layer structure or a multi-layer structure of two or more layers, so long as it does not deviate from the gist of the present invention. Among these, paper and resin films are preferred because they are inexpensive, easy to process, and easy to dispose of or recycle, and resin sheets are even more preferred because of their transparency.

The paper that can be used includes, for example, high-quality paper, craft paper, glassine paper, parchment paper, super-calendered craft paper, etc., whose surface has been silicone-coated.

Examples of resin films include films whose main component is polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyimide or polycarbonate. The surface of these films may be coated with a silicone resin release agent, a melamine-based resin release agent, a fluorine-based release agent or the like to adjust the peel strength. Among these, resin films whose main component is polyester are preferred in terms of appearance, ease of processing, durability, heat resistance, cost, etc.

The polyester is preferably one obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. The polyester may be a polyester made of one kind of aromatic dicarboxylic acid and one kind of aliphatic glycol, or a copolymer polyester in which one or more other components are further copolymerized.
Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol.
On the other hand, examples of dicarboxylic acids used as other components of the copolymerized polyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and sebacic acid, and examples of glycol components include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol. Also usable are oxycarboxylic acids such as p-oxybenzoic acid.
Representative examples of polyesters include polyethylene terephthalate obtained by polycondensation of terephthalic acid and ethylene glycol, and polyethylene naphthalate obtained by polycondensation of 2,6-naphthalenedicarboxylic acid and ethylene glycol.

The polyester film may be either a non-stretched film or a stretched film, but from the viewpoint of mechanical strength, a stretched film is preferred, and a biaxially stretched film is more preferred. In addition, the polyester film may be subjected to a surface treatment such as a corona treatment or a plasma treatment in advance.

The release film is preferably a matte film with minute irregularities formed on its surface, from the viewpoint of facilitating transfer to the present film and enhancing wettability of the release film when the present film is formed. There are no particular limitations on the method for making the film matte, and examples include a method of providing a release layer containing a filler on the surface, sandblasting (sand matting), etc.

[Preferred uses of this film]
The present film can be suitably used for bonding members together, and among others, it can be particularly suitably used for bonding components of an image display device, that is, as an adhesive film for the components of an image display device.
Specifically, it is suitably used for bonding members constituting display members (also referred to as "display members"), particularly flexible image display device components used in producing displays.

<Laminate for Image Display Device>
A laminate for an image display device according to one embodiment of the present invention (hereinafter, sometimes referred to as "the laminate for the image display device") is a laminate for an image display device having a configuration in which two components of an image display device are laminated with the present film interposed therebetween. Also, the laminate for the image display device is preferably a laminate for a flexible image display device having a configuration in which two components of a flexible image display device are laminated with the present film interposed therebetween.

Among the components of this laminate for an image display device, the film is as described above, and the components other than the film are described below.

(Image display device components)
Examples of the image display device components constituting the present laminate for image display devices include flexible image display device components. Examples of the flexible image display device components include flexible displays such as organic electroluminescence (EL) displays, cover lenses (cover films), polarizing plates, polarizers, retardation films, barrier films, viewing angle compensation films, brightness improvement films, contrast improvement films, diffusion films, semi-transmissive reflective films, electrode films, transparent conductive films, metal mesh films, and touch sensor films. Any one of these or two of them may be used in combination. For example, a combination of a flexible display and other flexible image display device components, or a combination of a cover lens and other flexible image display device components may be used.

Note that a component of a flexible image display device means a component having a curved or bendable portion, particularly a component having a portion that can be repeatedly bent. In particular, it is preferable that the component be capable of being fixed into a curved shape with a radius of curvature of 25 mm or more, and particularly that the component be capable of withstanding repeated bending action with a radius of curvature of less than 25 mm, and more preferably, less than 3 mm.

In the above-mentioned configuration, the main components of the flexible image display device components include a resin sheet, glass, or the like.
Examples of the material of such a resin sheet include polyester resin, cycloolefin resin, triacetyl cellulose resin, polymethyl methacrylate resin, polyurethane, epoxy resin, polyimide resin, and aramid resin, which may be one type of resin or two or more types of resin. Among them, a resin sheet containing at least one type of resin selected from the group consisting of polyester resin, cycloolefin resin, triacetyl cellulose resin, polymethyl methacrylate resin, epoxy resin, polyimide resin, aramid resin, and polyurethane resin as a main component is preferable.
Here, the term "main component" refers to a component that occupies the largest weight ratio among the components that make up the flexible image display device component, and specifically, it is a component that occupies 50 mass % or more of the resin composition (resin sheet) that forms the flexible image display device component, and preferably 55 mass % or more, and particularly preferably 60 mass % or more.
The flexible image display device components may also be made of thin glass.

In the above-mentioned configuration, it is preferable that one of the two flexible image display device components, i.e., the first flexible image display device component, has a tensile strength at 25°C measured in accordance with ASTM D882 of 10 to 900 MPa, more preferably 15 to 800 MPa, and particularly preferably 20 to 700 MPa.
If the tensile strength (ASTM D882) at 25° C. of one of the flexible image display device constituent members is within the above range, it is preferable since it is less likely to crack even when bent.

Furthermore, with regard to the other flexible image display device component, i.e., the second flexible image display device component, the tensile strength at 25°C measured in accordance with ASTM D882 is preferably 10 to 900 MPa, more preferably 15 to 800 MPa, and particularly preferably 20 to 700 MPa.
If the tensile strength (ASTM D882) at 25° C. of the other component of the flexible image display device is within the above range, it is preferable since it is less likely to crack even when bent.

Examples of the flexible image display device constituent members having high tensile strength include polyimide films, polyester films, and aramid films, and the tensile strength of these films is generally 900 MPa or less.
On the other hand, examples of the flexible image display device constituent members having a slightly low tensile strength include triacetyl cellulose (TAC) film and cycloolefin polymer (COP) film, and the tensile strength of these films is usually 10 MPa or more.
Even if the present laminate for flexible image display devices includes flexible image display device components made of such materials having a slightly low tensile strength, defects such as cracks can be suppressed by the action of the present film.

<Method of manufacturing the laminate for the image display device>
The method for manufacturing the present laminate for an image display device is not particularly limited, and as described above, for example, the present film may be formed by applying the resin composition onto a component of an image display device, preferably onto a component of a flexible image display device, or the present film may be formed in advance and then laminated to a component of an image display device, preferably a flexible image display device.

<Image display device>
An image display device according to an embodiment of the present invention (hereinafter, sometimes referred to as "this image display device") is an image display device incorporating a laminate for an image display device having a configuration in which two image display device components are bonded together via the present film. For example, by laminating a laminate for an image display device having a configuration in which two image display device components are bonded together via the present film on another image display device component, the present image display device including the laminate can be formed.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. In the examples, "parts" refers to parts by mass.

The following materials were prepared prior to the examples.

[Epoxy resin (A)]
(A-1): Bisphenol A type epoxy resin ("jER1256B40" manufactured by Mitsubishi Chemical Corporation, number average molecular weight 45,000, epoxy equivalent 6,700 g/eq)
(A'-1): Bisphenol A type epoxy resin ("jER1010" manufactured by Mitsubishi Chemical Corporation, number average molecular weight 30,000, epoxy equivalent 4,000 g/eq)

[Urethane resin (B)]
(B-1): Polyurethane resin ("Takelac TE-5899" manufactured by Mitsui Chemicals, Inc., storage modulus (E') at 20°C: 5.6 x 10 ⁶ Pa, glass transition temperature (Tg): -37°C)
(B-2): Polyurethane resin ("MT Olestar NL2249E" manufactured by Mitsui Chemicals, Inc., storage modulus (E') at 20°C: 1.5 x 10 ⁸ Pa, glass transition temperature (Tg): -27°C)

[Epoxy resin curing agent (C)]
(C-1): 2-ethyl-4-methylimidazole ("Curesol 2E4MZ" manufactured by Shikoku Kasei Corporation)
(C-2): Polyoxypropylenediamine ("Jeffamine D-230" manufactured by HUNTSMAN, weight average molecular weight 230)
(C-3): Polyoxypropylenediamine ("Jeffamine D-400" manufactured by HUNTSMAN, weight average molecular weight 400)
(C-4): Polyoxypropylenediamine ("Jeffamine D-2000" manufactured by HUNTSMAN, weight average molecular weight 2,000)

[Epoxy compound (D)]
(d1-1): Urethane-modified epoxy resin ("EPU-73B" manufactured by ADEKA Corporation, viscosity at 25°C 130,000 mPa·s, epoxy equivalent 245 g/eq)
(d1-2): Epoxidized polybutadiene ("JP-200" manufactured by Nippon Soda Co., Ltd., viscosity at 45°C: 150,000 mPa·s, epoxy equivalent: 220 g/eq)
(d2-1): Bisphenol A novolac type epoxy resin ("jER157S65B80" manufactured by Mitsubishi Chemical Corporation, softening point 80°C, epoxy equivalent 205g/eq)

[Silane coupling agent (E)]
(E-1): 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Silicones)

[Liquid epoxy compound (F)]
(F-1): 2-ethylhexyl glycidyl ether ("YED188" manufactured by Mitsubishi Chemical Corporation, boiling point at 0.4 hPa: 61° C., equivalent boiling point at 1 atmosphere: 253° C., viscosity at 25° C.: 4 mPa·s, epoxy equivalent: 180 to 196 g/eq)
(F-2): 1,6-hexanediol diglycidyl ether ("YED216D" manufactured by Mitsubishi Chemical Corporation, boiling point at 6.7 hPa of 177°C, equivalent boiling point at 1 atmospheric pressure of 344°C, viscosity at 25°C of 11 mPa·s, epoxy equivalent of 110 to 130 g/eq)

[Solvent (G)]
(G-1): Toluene (G-2): Methyl ethyl ketone (G-3): Ethyl acetate (G-4): Isopropanol

[Release film]
Release film consisting of a polyester film and a silicone-based release layer (Mitsui Chemicals Tohcello "SP-PET (registered trademark) O3-BU" (100 μm))

Example 1
A resin composition was prepared by mixing epoxy resin (A-1), urethane resin (B-1), epoxy resin curing agent (C-1), and epoxy compound (d2-1) in the ratios shown in Table 1 below. Next, solvents (G-1) to (G-4) were mixed with the resin composition in the ratios shown in Table 1 below to prepare a resin composition. The epoxy equivalent of the resin composition was 5,198 g/eq.
The prepared resin composition was applied onto a release film using an applicator so that the thickness after drying was 25 μm, and then heated at 120° C. for 5 minutes using a constant temperature dryer. After that, the resin composition was naturally cooled to room temperature (25° C.) to primarily cure the resin composition, and an adhesive film with a release film of Example 1 was obtained.

<Examples 2 to 9 and Comparative Examples 1 to 3>
Each resin composition was obtained in the same manner as in Example 1, except that the ratio of each material in the resin composition was changed to the amount shown in Table 1 below. The epoxy equivalent of each resin composition is shown in Table 1 below. In addition, adhesive films with release films of Examples 2 to 9 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that each obtained resin composition was used.
In Comparative Example 3, repelling occurred when the resin composition was applied onto the release film, and a uniform adhesive film was not obtained, making it impossible to carry out subsequent evaluation.

The following evaluations were carried out using the adhesive films with release films obtained in Examples 1 to 9 and Comparative Examples 1 and 2. The results are shown in Table 1 below.

(1) Storage modulus (E') and loss tangent (Tan δ)
The adhesive films with release films prepared in Examples 1 to 9 and Comparative Examples 1 and 2 were heat-treated at a temperature of 170°C for 30 minutes. Thereafter, the release film was peeled off, and the adhesive film was cut into 4 mm x 40 mm to prepare a measurement sample. This measurement sample was subjected to dynamic viscoelasticity measurement in accordance with JIS K7244-4:1999 using a viscoelasticity spectrometer "DVA-200 (manufactured by IT Measurement & Control Co., Ltd.)" in tension mode under conditions of a frequency of 1 Hz, a strain of 0.1%, a temperature range of -50 to 300°C, and a heating rate of 3°C/min, and the storage modulus (E') value at 100°C and the loss tangent (Tan δ) value at 50°C were read.

(2) Glass transition temperature (Tg1)
The release film was peeled off from the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2, and the glass transition temperature of the adhesive film was measured based on the "midpoint glass transition temperature: Tmg" of JIS K7121 "Method for measuring transition temperature of plastics." Specifically, a differential scanning calorimeter "DSC8500" manufactured by PerkinElmer Japan was used to measure the glass transition temperature (Tg1) by increasing the temperature from 3 to 250°C at 10°C/min.

(3) Exothermic peak temperature (T1) and heat quantity (J/g)
The DSC curve obtained in the above (1) glass transition temperature (Tg1) measurement was checked for the presence or absence of an exothermic peak in the temperature range of 120° C. or higher and 200° C. or lower, and the temperature (T1) and heat quantity (J/g) of the exothermic peak were determined.

(4) Solvent Content The solvent content was measured under the following conditions using HS-GC/MS (HS: "TurboMatrix HS 40" manufactured by PerkinElmer, GC/MS: "Claras 580" manufactured by PerkinElmer).
The release film was peeled off from the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2, 50 to 100 mg of the adhesive film was sampled, and this was placed in a 20 mL vial and sealed. The vial containing the sample was then heated at 120°C for 30 minutes, and 0.2 mL of the heated gas was injected into a gas chromatograph measuring device (GC measuring device) using a headspace autosampler to measure the amount of residual solvent (toluene and methyl ethyl ketone). The measured value was converted into the content (emission amount) [ppm] contained per mass of the sample.
[GC measurement device conditions]
Column: TC-WAX 0.2 μm (diameter 0.25 mm x 30 m)
Carrier gas: He 1.6 mL / min
Column head pressure: 9.8 psi (40° C.)
Inlet: Split (split ratio 19:1, temperature 200°C)
Column temperature: 40°C (5 min) - <+5°C/min> -150°C (0 min)
(The temperature was raised from 40° C. to 150° C. at a rate of 5° C./min, and the measurement was completed without holding the temperature at 150° C.)
Detector: FID (temperature 250°C)

(5) Total Light Transmittance, Haze The release film was peeled off from the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2, and the haze of the adhesive film at 400 nm and 650 nm was measured in accordance with JIS (haze: JIS K 7136) using a haze meter "NDH 7000II" manufactured by Nippon Denshoku Industries Co., Ltd.

(6) Yellowness (b ^* value)
The release film was peeled off from the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2, and the yellowness index (b ^* value) of the adhesive film was measured in accordance with ASTM E313 using a spectrophotometer "SD6000" manufactured by Nippon Denshoku Industries Co., Ltd. The light source was C and the viewing angle was 2°.

(7) Adhesive Strength Chemically strengthened glass as an adherend was pressure-bonded to the adhesive film surface of the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2 using a vacuum laminator under reduced pressure (gauge pressure 60 × 10 ^-6 Pa), press pressure 0.1 MPa, temperature 110 ° C., and 10 minutes. Next, a transparent polyimide (CPI) film (manufactured by Kolon Co., Ltd., thickness 50 μm) cut to a width of 25 mm and a length of 150 mm was pressure-bonded to the adhesive film surface exposed by peeling off the release film under the same conditions as above, except that the temperature was 170 ° C., using a vacuum laminator to obtain an adhesive strength measurement sample.
After the adhesive strength measurement sample was fixed to a jig, an end of the test piece was fixed to the chuck of a testing machine, and the adhesive film was peeled off from the adherend at a peel angle of 90° and a peel speed of 50 mm/min. The peel strength was measured with a load cell and used as the adhesive strength.

(8) Warping Resistance A thin film tempered glass (UTG, manufactured by Nippon Electric Glass Co., Ltd.) of 65 mm x 160 mm x 32 μm thick was press-bonded to the adhesive film surface of the adhesive film with release film produced in Examples 1 to 9 and Comparative Examples 1 and 2 under reduced pressure (gauge pressure: 60 x ^10-6 Pa), at a temperature of 170°C, for 10 minutes at a press pressure of 0.1 MPa using a vacuum laminator. After that, it was cooled to room temperature (25°C), and the release film was peeled off to obtain a sample for curl measurement.
The prepared sample was placed on a horizontal plate with the glass side facing down, and the average floating height (mm) of the four corners was calculated and evaluated according to the following evaluation criteria.
[Evaluation Criteria]
◯ (very good): The average height of the raised corners is 10 mm or less. × (poor): The average height of the raised corners is more than 10 mm.

From the results in Table 1, it was confirmed that the adhesive films of Examples 1 to 9, which are formed from a resin composition containing an epoxy resin (A), a urethane resin (B), and an epoxy resin curing agent (C) and have a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less, have excellent warping resistance.
In addition, the adhesive films of Examples 6 to 9, which are formed from a resin composition containing an epoxy resin (A), a urethane resin (B), an epoxy resin curing agent (C), and a liquid epoxy compound (d1), and have a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less, were confirmed to have excellent warping resistance.
Furthermore, it was confirmed that the adhesive films of Examples 1 to 9 had a high glass transition temperature and excellent heat resistance.
On the other hand, the adhesive film of Comparative Example 1, which did not contain the urethane resin (B), was poor in warp resistance. Also, Comparative Example 2, in which the storage modulus (E') at 100°C after curing exceeded 1 x ¹⁰ Pa, was poor in warp resistance.
In addition, in Comparative Example 3, in which an epoxy resin having an epoxy equivalent of less than 5,000 g/eq was used, it was not possible to form an adhesive film from the resin composition.

Example 10
A resin composition was prepared by mixing epoxy resin (A-1), liquid epoxy compound (F-1), solid epoxy compound (d2-1), and epoxy resin curing agent (C-1) in the ratios shown in Table 2 below. Next, a solvent (G-2) was mixed with the resin composition in the ratios shown in Table 2 below to prepare a resin composition. The epoxy equivalent of the resin composition was 682 g/eq.
The prepared resin composition was applied onto a release film using an applicator so that the thickness after drying would be 10 μm, and then heated at 120° C. for 5 minutes using a constant temperature dryer. The resin composition was then naturally cooled to room temperature (25° C.) to primarily cure, thereby obtaining an adhesive film with a release film of Example 10.

<Examples 11 to 13, Comparative Example 4>
Each resin composition was obtained in the same manner as in Example 10, except that the ratio of each material in the resin composition was changed to the amount shown in Table 2 below. The epoxy equivalent of each resin composition is shown in Table 2 below. In addition, adhesive films with release films of Examples 11 to 13 and Comparative Example 4 were obtained in the same manner as in Example 10, except that each of the obtained resin compositions was used.

The following evaluations were carried out using the adhesive films with release films obtained in Examples 10 to 13 and Comparative Example 4. The results are shown in Table 2 below.

(9) Glass transition temperature (Tg1)
The release film was peeled off from the adhesive film with release film produced in Examples 10 to 13 and Comparative Example 4, and the glass transition temperature of the adhesive film was measured based on the "midpoint glass transition temperature: Tmg" of JIS K7121 "Method for measuring transition temperature of plastics." Specifically, a differential scanning calorimeter "DSC8500" manufactured by PerkinElmer Japan was used to measure the glass transition temperature (Tg1) by increasing the temperature from 3 to 250°C at 10°C/min.

(10) Exothermic peak temperature (T1) and heat amount (J/g)
The DSC curve obtained in the above (1) glass transition temperature (Tg1) measurement was checked for the presence or absence of an exothermic peak in the temperature range of 120° C. or higher and 200° C. or lower, and the temperature (T1) and heat quantity (J/g) of the exothermic peak were determined.

(11) Solvent Content The solvent content was measured under the following conditions using HS-GC/MS (HS: "TurboMatrix HS 40" manufactured by PerkinElmer, GC/MS: "Claras 580" manufactured by PerkinElmer).
The release film was peeled off from the adhesive film with release film produced in Examples 10 to 13 and Comparative Example 4, and 50 to 100 mg of the adhesive film was sampled and placed in a 20 mL vial and sealed. The vial containing the sample was then heated at 120°C for 30 minutes, and 0.2 mL of the heated gas was injected into a gas chromatograph measuring device (GC measuring device) using a headspace autosampler to measure the amount of residual solvent (toluene and methyl ethyl ketone). The measured value was converted into the content (emission amount) [ppm] contained per mass of the sample.
[GC measurement device conditions]
Column: TC-WAX 0.2 μm (diameter 0.25 mm x 30 m)
Carrier gas: He 1.6 mL / min
Column head pressure: 9.8 psi (40° C.)
Inlet: Split (split ratio 19:1, temperature 200°C)
Column temperature: 40°C (5 min) - <+5°C/min> -150°C (0 min)
(The temperature was raised from 40° C. to 150° C. at a rate of 5° C./min, and the measurement was completed without holding the temperature at 150° C.)
Detector: FID (temperature 250°C)

(12) Adhesive Strength Chemically strengthened glass as an adherend was pressure-bonded to the adhesive film surface of the adhesive film with release film produced in Examples 10 to 13 and Comparative Example 4 using a vacuum laminator under reduced pressure (gauge pressure 60 × 10 ^-6 Pa), press pressure 0.1 MPa, temperature 110 ° C., and 10 minutes. Next, a transparent polyimide (CPI) film (manufactured by Kolon Co., Ltd., thickness 50 μm) cut to a width of 25 mm and a length of 150 mm was pressure-bonded to the adhesive film surface exposed by peeling off the release film under the same conditions as above, except that the temperature was 170 ° C., using a vacuum laminator to obtain an adhesive strength measurement sample.
After the adhesive strength measurement sample was fixed to a jig, an end of the test piece was fixed to the chuck of a testing machine, and the adhesive film was peeled off from the adherend at a peel angle of 90° and a peel speed of 50 mm/min. The peel strength was measured with a load cell to determine the adhesive strength.

(13) Warp Resistance A thin film tempered glass (UTG, manufactured by Nippon Electric Glass Co., Ltd.) of 65 mm x 160 mm x 32 μm thick was press-bonded to the adhesive film surface of the adhesive film with release film produced in Examples 10 to 13 and Comparative Example 4 under reduced pressure (gauge pressure: 60 x ^10-6 Pa) at a temperature of 170°C for 10 minutes at a press pressure of 0.1 MPa using a vacuum laminator. After that, it was cooled to room temperature (25°C) and the release film was peeled off to obtain a sample for curl measurement.
The prepared sample was placed on a horizontal plate with the glass side facing down, and the average floating height (mm) of the four corners was calculated and evaluated according to the following evaluation criteria.
[Evaluation Criteria]
◯ (very good): The average height of the raised corners is 10 mm or less. × (poor): The average height of the raised corners is more than 10 mm.

(14) Total Light Transmittance, Haze The release film was peeled off from the adhesive film with release film produced in Examples 10 to 13 and Comparative Example 4, and the haze of the adhesive film at 400 nm and 650 nm was measured in accordance with JIS (haze: JIS K 7136) using a haze meter "NDH 7000II" manufactured by Nippon Denshoku Industries Co., Ltd.

From the results in Table 2, the adhesive films of Examples 10 to 13 formed from the resin composition containing the epoxy resin (A) and the liquid epoxy compound (F) had excellent warping resistance. In addition, the adhesive films of Examples 10 to 13 had high glass transition temperatures and excellent heat resistance.
On the other hand, the adhesive film of Comparative Example 4, which did not contain the liquid epoxy compound (F), had poor warping resistance. Also, the adhesive film of Comparative Example 4 had a large amount of residual solvent, which resulted in a loss of suitability for subsequent processes.

The above examples show specific embodiments of the present invention, but the examples are merely illustrative and should not be interpreted as limiting. Various modifications that are obvious to those skilled in the art are intended to be within the scope of the present invention.

This film has little warping after curing and excellent heat resistance, making it suitable for use in a variety of laminates, and is particularly useful as an adhesive film for components of image display devices.

Claims (26)

The adhesive film is formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), and an epoxy resin curing agent (C), and the adhesive film has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less. The adhesive film according to claim 1, which has a loss tangent (Tan δ) of 0.1 or more at 50°C after curing. The adhesive film according to claim 1 or 2, wherein the resin composition further contains an epoxy compound (D) having an epoxy equivalent of 1,000 g/eq or less. The adhesive film according to claim 3, wherein the epoxy compound (D) includes a urethane-modified epoxy compound. The adhesive film according to claim 1 or 2, wherein the content of the urethane resin (B) in the resin composition is 10 to 85 mass %. The adhesive film according to claim 1 or 2, wherein the epoxy resin curing agent (C) includes an amine-based curing agent. 3. The adhesive film according to claim 1, wherein the urethane resin (B) has a storage modulus (E') at 20° C. of 1×10 ⁷ Pa or less. An adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, and a liquid epoxy compound (F) (excluding the epoxy resin (A)) having a boiling point of 170°C or more at 1 atmosphere. The adhesive film according to claim 8, wherein the liquid epoxy compound (F) has an epoxy equivalent of 1,000 g/eq or less. The adhesive film according to claim 8 or 9, wherein the resin composition contains a solid epoxy compound (d2) having an epoxy equivalent of 1,000 g/eq or less. The adhesive film according to claim 8 or 9, wherein the mass ratio [(A):(F)] of the epoxy resin (A) to the liquid epoxy compound (F) in the resin composition is 95:5 to 50:50. The adhesive film according to claim 10, wherein the mass ratio [(A):(d2)] of the epoxy resin (A) to the solid epoxy compound (d2) in the resin composition is 99:1 to 50:50. The adhesive film according to claim 8 or 9, wherein the resin composition contains an epoxy resin curing agent (C). The adhesive film according to claim 13, wherein the epoxy resin curing agent (C) includes an amine-based curing agent. An adhesive film formed from a resin composition containing an epoxy resin (A) having a number average molecular weight of 10,000 or more and an epoxy equivalent of 5,000 g/eq or more, a urethane resin (B), an epoxy resin curing agent (C), and a liquid epoxy compound (d1) having an epoxy equivalent of 1,000 g/eq or less, wherein the adhesive film has a storage modulus (E') at 100°C after curing of 1 x ¹⁰⁷ Pa or less. The adhesive film according to claim 15, wherein the epoxy resin curing agent (C) includes an amine-based curing agent. The adhesive film according to any one of claims 1, 8 and 15, wherein the epoxy equivalent of the resin composition is 400 to 50,000 g/eq. The adhesive film according to any one of claims 1, 8 and 15, which has an exothermic peak in the temperature range of 120 to 220°C when differential scanning calorimetry (DSC) is performed at a heating rate of 10°C/min, and the heat quantity of the exothermic peak is 5 J/g or more. The adhesive film according to claim 18, wherein the glass transition temperature (Tg1) determined by differential scanning calorimetry (DSC) at a heating rate of 10 ° C. / min is 0 to 120 ° C., and the temperature (T1) of the exothermic peak in the differential scanning calorimetry (DSC) and the glass transition temperature (Tg1) satisfy the following relationship.
T1-Tg1≧60 An adhesive film according to any one of claims 1, 8 and 15, having a solvent content of 10,000 ppm or less. An adhesive film according to any one of claims 1, 8 and 15, having a total light transmittance of 80% or more and a haze of 5% or less. An adhesive film with a release film, comprising the adhesive film according to any one of claims 1, 8 and 15 laminated with a release film. An adhesive film for a flexible image display device component, comprising the adhesive film according to any one of claims 1, 8 and 15. A laminate for a flexible image display device, comprising two image display device components laminated together via an adhesive film according to any one of claims 1, 8 and 15. The laminate for a flexible image display device according to claim 24, having a curved portion or a bendable portion. A flexible image display device comprising the laminate for a flexible image display device according to claim 24.