Adhesive composition and film-like sealing material

Abstract

To provide a high reliability epoxy resin-based adhesive composition and a film-like sealing material which maintain low viscosity, low temperature curing, high adhesion and power generation performance of a perovskite type solar cell before and after sealing.SOLUTION: An adhesive composition contains (A) a reaction product of a bifunctional type epoxy resin, a tri- or higher functional epoxy resin, and a saturation type acid anhydride, (B) a UV sensitive reaction initiator, and (C) a dilution solvent, wherein the component (A) has a ratio of the total molar number of epoxy groups of the bifunctional type epoxy resin and the tri- or higher functional epoxy resin to a molar number of the saturation type acid anhydride of 1.30 to 3.00, and a ratio of the molar number of the bifunctional type epoxy resin to the total molar number of the bifunctional type epoxy resin and the tri- or higher functional epoxy resin of 0.001 to 0.15.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition and a film-like sealing material. [Background technology]

[0002] The recent increase in demand for renewable energy has led to a demand for transparent solar cells. Perovskite solar cells are candidates for transparent solar cells, but when considering commercial use, unlike single-crystal or amorphous silicon solar cells, there is a demand for transparent film-type solar cells that can be applied to large areas so that they can be attached to building walls and windows. To realize such transparent film-type solar cells, adhesives with low viscosity, low-temperature curing properties, high adhesion, and high reliability before and after sealing are required (Patent Document 1).

[0003] Conventionally, adhesive compositions made of epoxy resins and saturated hydrocarbon acid anhydrides have been excellent in terms of low viscosity and high transparency, but because they are difficult to cure at the low temperatures applicable to perovskite solar cells, they are poor at maintaining power generation performance before and after encapsulation. Therefore, simple adhesive compositions made of epoxy resins and saturated hydrocarbon acid anhydrides are uncured, and as a result, power generation performance declines significantly, making them unsuitable as adhesive compositions or film-like encapsulants for solar cell encapsulation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-89946 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly reliable epoxy resin-based adhesive composition and film-like encapsulant that have low viscosity, cure at low temperature, high adhesion, and maintain the power generation performance of perovskite solar cells before and after encapsulation. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an adhesive composition containing (A) a reaction product of a difunctional epoxy resin represented by the following general formula (2), a tri- or higher functional epoxy resin represented by the following general formula (3), and a saturated acid anhydride represented by the following general formula (4), (B) a UV-sensitive reaction initiator, and (C) a diluent solvent, The component (A) is a compound represented by the following general formula (1): [ka] (In the formula, A is a saturated divalent hydrocarbon group. Each B is independently a group represented by general formula (1a) or general formula (1b). R2 is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Z is a single bond or an oxygen atom. k is an integer of 2 or more. * is a bond. The order of repeating unit l and repeating unit m in the formula is arbitrary.) [ka] (wherein R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (wherein A is the same as above.) The adhesive composition is characterized in that the amounts of the bifunctional epoxy resin, trifunctional or higher functional epoxy resin, and saturated acid anhydride are such that the ratio of the total number of moles of epoxy groups in the bifunctional epoxy resin and trifunctional or higher functional epoxy resin to the number of moles of the saturated acid anhydride is 1.30 to 3.00, and the number of moles of the bifunctional epoxy resin is 0.001 to 0.15 relative to the total number of moles of the bifunctional epoxy resin and trifunctional or higher functional epoxy resin.

[0007] Such an adhesive composition is a highly reliable epoxy resin adhesive composition that has low viscosity, cures at low temperature, has high adhesion, and is capable of maintaining the power generation performance of perovskite solar cells before and after sealing.

[0008] In this case, it is preferable that the reaction product is a polymer obtained by polymerizing the difunctional epoxy resin, the trifunctional or higher epoxy resin, and the saturated acid anhydride, and that the weight average molecular weight of the polymer is 2,000 to 20,000.

[0009] With such an adhesive composition, the above-described effects of the present invention are more favorable.

[0010] In the present invention, the component (A) preferably further contains a reaction product represented by the following general formula (5), which is obtained by reacting the compound represented by the general formula (1) with an alkoxysilane compound represented by the following general formula (6) or a partial hydrolyzate thereof: [ka] [ka] (In the formula, A, R2, R3, Z, k, and * are the same as above. Each B' is independently a group represented by general formula (5a) or general formula (5b). Each Z' is independently R4(OR5)2Si- or a group derived from a partial hydrolyzate of an alkoxysilane compound represented by general formula (6). R4 is a monovalent organic group including a vinyl group, a styryl group, an acryl group, a methacryl group, an amino group, a mercapto group, a ureido group, or an isocyanate group, and R5 is a monovalent organic group including a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[0011] Such an adhesive composition can achieve high adhesion to substrates such as glass.

[0012] In the present invention, it is preferable that the difunctional epoxy resin is a BisA type epoxy resin represented by the following general formula (2'), the tri- or higher functional epoxy resin is a triazine ring type trifunctional epoxy resin represented by the following general formula (3'), and the saturated acid anhydride is a saturated hydrocarbon type acid anhydride represented by the following general formula (4'). [ka] (wherein n is an integer of 1 or more). [ka] [ka]

[0013] With such an adhesive composition, the above-described effects of the present invention are even more favorable.

[0014] The present invention also provides a film-like sealing material comprising a dried product of the adhesive composition.

[0015] Such a film-like encapsulant can provide a good performance of maintaining the power generation performance of the perovskite solar cell before and after encapsulation.

[0016] The film-shaped sealing material further contains a residual solvent, and the residual solvent is preferably dimethylformamide and / or dimethylsulfoxide, and the residual amount per mass of the film-shaped sealing material is preferably 5000 ppm or less.

[0017] If the residual solvent dimethylformamide or dimethyl sulfoxide is contained in the adhesive layer at 5000 ppm or less, it will not have a particularly adverse effect on the JV characteristics. [Effects of the Invention]

[0018] The adhesive composition and film-like encapsulant of the present invention can be used as adhesive, cohesive, and transparent adhesives and adhesive films, and can be widely used in fields such as paints, electrical appliances, automobiles, and construction and building materials. Compared to conventional transparent resins, they exhibit excellent low-temperature curing properties. These properties allow them to maintain low-temperature curing properties and the power generation performance of perovskite solar cells before and after encapsulation, which are not possible with conventional transparent resin systems, making them suitable for use. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present inventors have conducted extensive research to overcome the above-mentioned drawbacks of the prior art. As a result, they have achieved high adhesion not only by using a reaction system between an epoxy resin and a saturated hydrocarbon acid anhydride, but also by incorporating, for example, a triazine ring-containing trifunctional epoxy resin, and incorporating a predetermined amount of the triazine ring-containing trifunctional epoxy resin into a BisA epoxy resin to construct a three-dimensional polymer structure. They have also achieved a film-like composition by incorporating an excess epoxy content relative to the saturated hydrocarbon acid anhydride to produce an oligomer. They have also achieved a low-viscosity film-like composition by incorporating an excess epoxy content relative to the saturated hydrocarbon acid anhydride within a predetermined range. They have also found that the epoxy resin adhesive composition (film-like adhesive composition) of the present invention has the properties of low viscosity, high adhesion, low-temperature curing, and excellent performance in maintaining the power generation performance of perovskite solar cells before and after sealing, which led to the present invention.

[0020] That is, the present invention provides an adhesive composition containing (A) a reaction product of a difunctional epoxy resin represented by the following general formula (2), a tri- or higher functional epoxy resin represented by the following general formula (3), and a saturated acid anhydride represented by the following general formula (4), (B) a UV-sensitive reaction initiator, and (C) a diluent solvent, The component (A) is a compound represented by the following general formula (1): [ka] (In the formula, A is a saturated divalent hydrocarbon group. Each B is independently a group represented by general formula (1a) or general formula (1b). R2 is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Z is a single bond or an oxygen atom. k is an integer of 2 or more. * is a bond. The order of repeating unit l and repeating unit m in the formula is arbitrary.) [ka] (wherein R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (wherein A is the same as above.) The adhesive composition is characterized in that the amounts of the bifunctional epoxy resin, trifunctional or higher functional epoxy resin, and saturated acid anhydride are such that the ratio of the total number of moles of epoxy groups in the bifunctional epoxy resin and trifunctional or higher functional epoxy resin to the number of moles of the saturated acid anhydride is 1.30 to 3.00, and the number of moles of the bifunctional epoxy resin relative to the total number of moles of the bifunctional epoxy resin and trifunctional or higher functional epoxy resin is 0.001 to 0.15.

[0021] The present invention will be described in detail below, but the present invention is not limited thereto.

[0022] The present invention relates to a highly reliable epoxy resin adhesive composition and film-like encapsulant that have low viscosity, low-temperature curing properties, high adhesion, and maintain the power generation performance of perovskite solar cells before and after encapsulation.

[0023] The adhesive composition of the present invention contains (A) a reaction product of a specific difunctional epoxy resin, a tri- or higher functional epoxy resin, and a saturated acid anhydride, (B) a UV-sensitive initiator, and (C) a diluent solvent, wherein the amounts of the difunctional epoxy resin, tri- or higher functional epoxy resin, and saturated acid anhydride are such that the ratio of the total moles of epoxy groups in the difunctional epoxy resin and the tri- or higher functional epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the ratio of the moles of the difunctional epoxy resin to the total moles of the difunctional epoxy resin and the tri- or higher functional epoxy resin is 0.001 to 0.15. In addition to the above components (A) to (C), other components may also be contained as necessary. The adhesive composition of the present invention can also be in the form of a film (film-like adhesive composition). The components of the adhesive composition of the present invention will be described below.

[0024] [Component (A)] Component (A) is a reaction product of a difunctional epoxy resin represented by the following general formula (2), a tri- or higher functional epoxy resin represented by the following general formula (3), and a saturated acid anhydride represented by the following general formula (4), and is a compound represented by the following general formula (1). [ka]

[0025] In the above formula, A is a saturated divalent hydrocarbon group. Each B is independently a group represented by general formula (1a) or general formula (1b). R2 is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Z is a single bond or an oxygen atom. k is an integer of 2 or more. * is a bond. The order of repeating unit l and repeating unit m in the formula is arbitrary.

[0026] [ka] (wherein R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (wherein A is the same as above.)

[0027] Thus, the compound represented by general formula (1) is a reaction product of a difunctional epoxy resin, a tri- or higher functional epoxy resin, and a saturated acid anhydride (saturated hydrocarbon acid anhydride), and has epoxy residues of a difunctional epoxy and epoxy residues of a tri- or higher functional epoxy in the skeleton.

[0028] In the synthesis of component (A), specific compounds (difunctional epoxy resin, tri- or higher functional epoxy resin, saturated acid anhydride) described below are reacted in amounts such that the ratio of the total moles of epoxy groups in the difunctional epoxy resin and tri- or higher functional epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the moles of the difunctional epoxy resin relative to the total moles of the difunctional epoxy resin and tri- or higher functional epoxy resin is 0.001 to 0.15. In general formula (1), l and m are numbers that satisfy the above conditions.

[0029] <Difunctional epoxy resin> The difunctional epoxy resin used in the synthesis reaction of the compound represented by general formula (1) is represented by the following general formula (2): where R2 is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring, and Z is a single bond or an oxygen atom. [ka]

[0030] The epoxy resin used as the bifunctional epoxy resin (component of general formula (2)) in the present invention is a compound having two epoxy groups in the molecule. In particular, the epoxy equivalent is preferably 50 to 5000 g / eq, more preferably 100 to 500 g / eq.

[0031] The weight average molecular weight of the epoxy resin is usually less than 10,000, preferably 400 to 9,000, and more preferably 500 to 8,000. The weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) and is the weight average molecular weight converted into standard polystyrene (the same applies hereinafter).

[0032] Examples of such epoxy resins include diglycidyl ethers of bis(4-hydroxyphenyl)methane, 2,2'-bis(4-hydroxyphenyl)propane, or halides thereof, as well as condensation polymers of these compounds (so-called bisphenol F type epoxy resins, bisphenol A type epoxy resins, etc.); diene epoxides such as butadiene diepoxide and vinylcyclohexene dioxide; epoxy glycidyl ethers or polyglycidyl esters obtained by condensing epichlorohydrin with dihydric phenols or dihydric alcohols such as 1,2-dihydroxybenzene and resorcinol, such as diglycidyl ether of resorcinol, 1,4-bis(2,3-epoxypropoxy)benzene, 4,4'-bis(2,3-epoxypropoxy)diphenyl ether, 1,4-bis(2,3-epoxypropoxy)cyclohexene, and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate. Other examples include divalent epoxy resins such as epoxy novolacs (i.e., novolac epoxy resins) obtained by condensing novolac-type phenolic resins (or halogenated novolac-type phenolic resins) such as phenol novolac and cresol novolac with epichlorohydrin; epoxidized polyolefins and epoxidized polybutadienes epoxidized by a peroxidation method; naphthalene ring-containing epoxy resins; biphenyl-type epoxy resins; phenol aralkyl-type epoxy resins; biphenyl aralkyl-type epoxy resins; and cyclopentadiene-type epoxy resins.

[0033] Among these, bisphenol F type epoxy resins and bisphenol A type epoxy resins, which are liquid at room temperature, are preferred as the component of general formula (2).

[0034] Commercially available products can also be used as the component of general formula (2), such as JER-1001 (manufactured by Mitsubishi Chemical Corporation), a BisA type epoxy resin.

[0035] These epoxy resins can be used singly or in combination of two or more.

[0036] <Epoxy resins with three or more functionalities> The tri- or higher functional epoxy resin used in the synthesis reaction of the compound represented by general formula (1) is represented by the following general formula (3). Here, R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Z is a single bond or an oxygen atom. k is an integer of 2 or more, preferably 2. [ka]

[0037] Examples of trifunctional or higher functional epoxy resins include glycidylamine-type epoxy resins, heterocyclic epoxy resins, and trifunctional or higher functional aromatic or aliphatic epoxy resins. Examples of heterocyclic epoxy resins include epoxy resins having a heterocycle such as a triazine skeleton. Examples of trifunctional or higher functional aromatic epoxy resins include polyhydric phenol epoxy resins, and examples of trifunctional or higher functional aliphatic epoxy resins include polyhydric alcohol epoxy resins.

[0038] (glycidylamine epoxy resin) Examples of glycidylamine type epoxy resins include diaminodiphenylmethane type epoxy resins such as tetraglycidyldiaminodiphenylmethane, diaminodiphenylsulfone type epoxy resins such as tetraglycidyldiaminodiphenylsulfone, tetraglycidylmetaxylenediamine, tetraglycidyl 1,3-bisaminomethylcyclohexane, hydantoin type epoxy resins, and aminophenol type epoxy resins. Other specific examples of glycidylamine-type epoxy resins include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane (product name Epotohto YH-434L, Nippon Steel & Sumikin Chemical Co., Ltd.), N,N,N',N'-tetraglycidyl-1,3-benzenedi(methanamine) (product name TETRAD-X, Mitsubishi Gas Chemical Company, Inc.), 4-(glycidyloxy)-N,N-diglycidylaniline, and 3-(glycidyloxy)-N,N-diglycidylaniline.

[0039] These epoxy resins can be used singly or in combination of two or more.

[0040] (heterocyclic epoxy resin) Preferred examples of heterocyclic epoxy resins include triazine derivative epoxy resins such as 1,3,5-triazine nucleus derivative epoxy resins. Epoxy resins having an isocyanurate ring are particularly excellent in light resistance and electrical insulation, and those having a divalent epoxy group per isocyanurate ring are preferred, and those having a trivalent epoxy group are more preferred. Specific examples of such heterocyclic epoxy resins include triglycidyl isocyanurate (product name TEPIC-S, Nissan Chemical Industries, Ltd.).

[0041] (Aromatic or aliphatic epoxy resin with three or more functionalities) Examples of tri- or higher functional aromatic or aliphatic epoxy resins include epoxy novolacs (i.e., novolac-type epoxy resins) obtained by condensing epichlorohydrin with a novolac-type phenolic resin (or a halogenated novolac-type phenolic resin) having three or more epoxy groups in one molecule, such as phenol novolac or cresol novolac; epoxidized polyolefins and epoxidized polybutadienes epoxidized by a peroxidation method; naphthalene ring-containing epoxy resins; biphenyl-type epoxy resins; phenol aralkyl-type epoxy resins; biphenyl aralkyl-type epoxy resins; and cyclopentadiene-type epoxy resins. Furthermore, specific examples of trifunctional or higher aromatic epoxy resins include tetrafunctional naphthalene-type epoxy resins (product name Epiclon HP-4700, DIC Corporation) and triphenylmethane-type epoxy resins (product name 1032H60, Mitsubishi Chemical Corporation).

[0042] <Saturated acid anhydride> The saturated acid anhydride used in the synthesis reaction of the compound represented by general formula (1) is represented by the following general formula (4): where A is a saturated divalent hydrocarbon group. [ka]

[0043] The acid anhydride used as the epoxy resin curing agent is not particularly limited as long as it is a saturated acid anhydride. Examples of saturated acid anhydrides include succinic anhydride. or , methylsuccinic acid, ethylsuccinic acid, 2,2-dimethylsuccinic acid, 3-oxabicyclo(3,1,0)hexane-2,4-dione, tetradecylsuccinic acid, hexadecylsuccinic acid, 2-octadecylsuccinic acid anhydride Hexahydrophthalic acids such as hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, and 4-ethylhexahydrophthalic acid anhydride , 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo(2,2,2)octane-2,3-dicarboxyanhydride, norcantharidin, cantharidin, and the like.

[0044] The saturated acid anhydride may be commercially available, for example, Rikacid MH (manufactured by New Japan Chemical Co., Ltd.).

[0045] These saturated acid anhydrides can be used either individually or in combination of two or more.

[0046] In the present invention, the compound represented by general formula (1) (component (A)) is a reaction product of a difunctional epoxy resin represented by general formula (2), a tri- or higher functional epoxy resin represented by general formula (3), and a saturated acid anhydride represented by general formula (4). The amounts of the bifunctional epoxy resin, tri- or higher functional epoxy resin, and saturated acid anhydride must be such that the ratio of the total moles of epoxy groups in the bifunctional epoxy resin and tri- or higher functional epoxy resin (total moles of epoxy groups) to the moles of the saturated acid anhydride (moles of acid anhydride) ((moles of total epoxy groups) / (moles of acid anhydride)) is 1.30 to 3.00, and the moles of the bifunctional epoxy resin relative to the total moles of the bifunctional epoxy resin and tri- or higher functional epoxy resin (bifunctional epoxy resin ratio) is 0.001 to 0.15. By keeping the ratios of each component within these ranges, it is possible to obtain a highly reliable epoxy resin-based adhesive composition or film-like encapsulant that has low viscosity, low-temperature curing properties, high adhesion, and maintains the power generation performance of perovskite solar cells before and after encapsulation. On the other hand, if the ratio (total number of moles of epoxy groups) / (number of moles of acid anhydride) is less than 1.30, unreacted curing agent remains in the cured product, which can reduce the moisture resistance of the resulting cured product or make it difficult to solidify at room temperature even after prepolymerization, resulting in poor adhesive strength after curing and a significant decrease in power generation performance. Furthermore, if the ratio (total number of moles of epoxy groups) / (number of moles of acid anhydride) exceeds 3.00, poor curing can occur and reliability can decrease. If the bifunctional epoxy resin ratio is less than 0.001 or more than 0.15, a three-dimensional polymer structure cannot be constructed, resulting in poor adhesive strength after curing and a significant decrease in power generation performance.

[0047] The prepolymer can be synthesized by mixing and reacting the bifunctional epoxy resin, trifunctional or higher epoxy resin, and saturated acid anhydride described above at 50 to 200°C, preferably 60 to 120°C, and more preferably 70 to 110°C, for 1 to 20 hours, preferably 2 to 15 hours. The desired resin can be produced by adding the components described below, and the order of addition of the components can be any. For example, when heat-mixing the bifunctional epoxy resin, trifunctional or higher epoxy resin, and saturated acid anhydride, a portion of the trifunctional or higher epoxy resin can be first heat-mixed with the other components (first heat-mixing), and the remaining trifunctional or higher epoxy resin can be added to the resulting reaction product and further heat-mixed (second heat-mixing) to obtain the desired reaction product. The temperature, stirring time, stirring means, etc., may differ between the first heat-mixing and the second heat-mixing. The heat-mixing may be performed in the presence of a diluent solvent described below.

[0048] The reaction product contained in the adhesive composition of the present invention is preferably a polymer obtained by polymerizing a difunctional epoxy resin, a tri- or higher functional epoxy resin, and a saturated acid anhydride, and the weight-average molecular weight of the polymer is preferably 2000 to 20000. If the weight-average molecular weight is 2000 or more, the adhesive composition can be formed into a film, and if it is 20000 or less, the melt viscosity is suitable and sufficient adhesive strength is achieved.

[0049] The weight average molecular weight is measured by GPC and is the weight average molecular weight converted into standard polystyrene. The GPC measurement conditions are as follows: [Measurement conditions] Developing solvent: tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Refractive index detector (RI) Column: TSKGuard column SuperH-L TSKgelSuperH4000(6.0mm ID×15cm×1) TSKgelSuperH3000(6.0mm ID×15cm×1) TSKgelSuperH2000(6.0mm ID×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 20 μL (0.5% by mass THF solution)

[0050] <Alkoxysilane compounds and alkoxysilane partial hydrolysates> The adhesive composition of the present invention preferably further contains, as component (A), a reaction product represented by the following general formula (5), which is obtained by reacting the compound represented by the above general formula (1) with an alkoxysilane compound represented by the following general formula (6) or a partial hydrolyzate thereof: [ka] [ka] (In the formula, A, R2, R3, Z, k, and * are the same as above. Each B' is independently a group represented by general formula (5a) or general formula (5b). Each Z' is independently R4(OR5)2Si- or a group derived from a partial hydrolyzate of an alkoxysilane compound represented by general formula (6). R4 is a monovalent organic group including a vinyl group, a styryl group, an acryl group, a methacryl group, an amino group, a mercapto group, a ureido group, or an isocyanate group, and R5 is a monovalent organic group including a methyl group, an ethyl group, a propyl group, or an isopropyl group.)

[0051] An adhesive composition (or film-like adhesive composition) containing a reaction product represented by general formula (5), which is obtained by reacting a compound represented by general formula (1) with an alkoxysilane compound represented by general formula (6) or a partial hydrolyzate thereof (hereinafter also referred to as "alkoxysilane compound, etc."), can achieve high adhesion to glass, etc., because the alkoxysilane compound, etc., has a hydrolyzable alkoxysilyl group.

[0052] The alkoxysilane or alkoxysilane partial hydrolysis condensate component is a partial hydrolysis condensate synthesized by a hydrolysis condensation reaction of alkoxysilanes containing at least one or more alkoxysilanes represented by the above general formula (6), and is an alkoxysilane partial hydrolysis condensate having a weight-average molecular weight of 300 or more and 30,000 or less, and a residual alkoxy content of 2 wt % or more and 50 wt % or less.

[0053] The partial hydrolysis condensate synthesized by the hydrolysis condensation reaction of alkoxysilanes containing one or more of the alkoxysilanes represented by general formula (6) is a silicone having a three-dimensional network structure mainly composed of trifunctional siloxane units, and includes not only partial hydrolysis condensates synthesized directly by the hydrolysis condensation reaction of alkoxysilanes containing one or more of the alkoxysilanes represented by general formula (6), but also partial hydrolysis condensates synthesized by the hydrolysis condensation reaction of alkoxysilanes containing one or more of the alkoxysilanes represented by general formula (6) and then further hydrolysis condensation. The alkoxysilane partial hydrolysis condensate of general formula (6) is not particularly limited as long as it has a trifunctional siloxane unit.

[0054] Examples of the partial hydrolysis condensation product of alkoxysilane containing the trifunctional alkoxysilane represented by the general formula (6) include (i) Wacker Asahi Kasei Corp. products: SY231 (containing methoxy, phenyl, and methyl groups (alkoxy equivalent 222)), SY550 (containing methoxy, phenyl, and methyl groups), SY300 (containing hydroxyl, phenyl, and propyl groups (hydroxyl value 3% by weight)), SY409 (containing hydroxyl, phenyl, and methyl groups (hydroxyl value 2.5% by weight)), SY430 (containing hydroxyl and phenyl groups (hydroxyl value 5% by weight)), IC836 (containing hydroxyl, phenyl, and propyl groups (hydroxyl value 5% by weight)), (ii) Shin-Etsu Chemical Co., Ltd.: straight silicone resins: KR220L (solid), KR242A, KR271, KR282 (weight average molecular weight (Mw) = 100,000 to 200,000, containing hydroxyl groups (hydroxyl value 1% by weight)), KR300, KR311 (Mw = 6,000 to 10,000, containing hydroxyl groups (hydroxyl value 4.5% by weight)), silicone intermediates: KC89 (containing methoxy and methyl groups (methoxy group content 45% by weight)), KR500 (containing methoxy groups (methoxy group content 30% by weight)), KR21 2 (Mw=2000-3000, containing hydroxyl, methyl, and phenyl groups (hydroxyl value 5% by weight)), KR213 (containing methoxy, methyl, and phenyl groups (methoxy group content 22% by weight)), KR9218 (containing methoxy, methyl, and phenyl groups (methoxy group content 15% by weight)), KR251, KR400, KR255, KR216, KR152, (iii) Dow Corning Toray Co., Ltd.: silicone resins: 804 RESIN (phenylmethyl type), 805 RESIN (phenylmethyl type), 806 A RESIN (phenylmethyl type), 8 40RESIN (phenylmethyl type), SR2400 (methyl type), silicone intermediate: 3037INTERMEDIATE (Mw=1000, contains methoxy, phenyl, and methyl groups (methoxy group content 18% by weight)), 3074INTERMEDIATE (Mw=1400, contains methoxy, phenyl, and methyl groups (methoxy group content 17% by weight)), Z-6018 (Mw=2000, contains hydroxyl, phenyl, and propyl groups (hydroxyl value 6% by weight)), 217FLAKE (Mw=2000, contains hydroxyl and phenyl groups (hydroxyl value 6% by weight)),220FLAKE (Mw=3000, contains hydroxyl, phenyl, and methyl groups (hydroxyl value 6% by weight)), 233FLAKE (Mw=3000, contains hydroxyl, phenyl, and methyl groups (hydroxyl value 6% by weight)), 249FLAKE (Mw=3000, contains hydroxyl, phenyl, and methyl groups (hydroxyl value 6% by weight)), QP8-5314 (Mw=200, contains methoxy, phenyl, and methyl groups (methoxy content 42% by weight)), SR2402 (Mw=1500, contains methoxy and methyl groups (methoxy content 31% by weight)), AY42-161 (Mw=1500, contains methoxy and methyl groups (methoxy content 36% by weight)), AY42-162 (Mw=2500, contains methoxy Examples of alkoxysilane derivatives include silsesquioxane derivatives manufactured by Toagosei Co., Ltd., such as OX-SQ (containing an oxetanyl group (functional group equivalent: 263 g / eq)), OX-SQ-H (containing an oxetanyl group (functional group equivalent: 283 g / eq)), OX-SQSI-20 (containing an oxetanyl group (functional group equivalent: 262 g / eq)), and AC-SQ (containing an acryloyl group (functional group equivalent: 165 g / eq)), and alkoxysilane partial hydrolysis condensates obtained by further hydrolysis and condensation of these alkoxysilane partial hydrolysis condensates.

[0055] In the adhesive composition of the present invention, the compound represented by general formula (1) is preferably a reaction product of the following difunctional epoxy resin, trifunctional epoxy resin, and saturated acid anhydride. That is, it is preferred that the difunctional epoxy resin is a BisA epoxy resin represented by the following general formula (2'), the tri- or higher functional epoxy resin is a trifunctional triazine ring epoxy resin represented by the following general formula (3'), and the saturated acid anhydride is a saturated hydrocarbon acid anhydride represented by the following general formula (4'). Specifically, the BisA epoxy resin can be JER-1001 (manufactured by Mitsubishi Chemical Corporation), the trifunctional triazine ring epoxy resin can be TEPIC-S (manufactured by Nissan Chemical Industries, Ltd.), and the saturated hydrocarbon acid anhydride can be Rikacid MH (manufactured by New Japan Chemical Co., Ltd.).

[0056] [ka] (wherein n is an integer of 1 or more). [ka] [ka]

[0057] [(B) Component] The adhesive composition of the present invention contains a UV-sensitive reaction initiator as component (B). In the present invention, a UV-sensitive initiator (photocationic polymerization initiator) is required. This is a compound that initiates the polymerization of the resin by light. There are no particular limitations on the compound as long as it has this function, and any compound can be used. A preferred example of the UV-sensitive initiator is an onium salt having a structure represented by the following formula (7). This onium salt is a compound that undergoes a photoreaction to release a Lewis acid. {R1 a R2 b R3 c R4 d Y} m+ {MX n+m} m- (7)

[0058] In formula (7), the cation is an onium ion, Y is S, Se, Te, P, As, Sb, Bi, O, I, Br, Cl, or N2 (diazo group), R1, R2, R3, and R4 are the same or different organic groups, a, b, c, and d are each an integer of 0 to 3, and (a+b+c+d) is equal to the valence of Y. Here, examples of the organic groups of R1 to R4 include aryl groups such as a phenyl group, a biphenyl group, and a naphthyl group, aryl groups mono- and poly-substituted with C1 to C18 alkyl groups, a phenoxyphenyl group, and a thiophenylphenyl group.

[0059] M is the halide complex {MX n+m X is a metal or metalloid constituting the central atom of M, such as B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, Co, etc. X is a halogen atom such as F, Cl, or Br, m is the net charge of the halide complex ion, and n is the valence of M.

[0060] In formula (7), specific examples of the onium ion include diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, bis{4-(diphenylsulfonio)-phenyl}sulfide, bis{4-(di(4-(2-hydroxyethyl)phenyl)sulfonio)-phenyl}sulfide, η 5 -2,4-(cyclopentadiphenyl){1,2,3,4,5,6-η-(methylethyl)benzene}-iron(1+), etc.

[0061] In formula (7), specific examples of the anion include tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, etc. These UV-sensitive reaction initiators can be used alone or in combination of two or more.

[0062] As the UV-sensitive reaction initiator, a commercially available product may be used, for example, CPI-300 manufactured by San-Apro Co., Ltd.

[0063] The UV-sensitive reaction initiator is preferably added in an amount of 0.1 to 10 mass %, particularly 1 to 3 mass %, of the total amount of organic components. If the amount added is 0.1 mass % or more, good curability is achieved, and if it is 10 mass % or less, good curability is achieved but storage stability is poor.

[0064] [(C) component] The adhesive composition of the present invention contains a diluent solvent as component (C). An organic solvent is usually used as the dilution solvent. Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone (hereinafter also abbreviated as "MEK"), and cyclohexanone; acetate ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitol solvents such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; aromatic ether solvents such as anisole; amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; and aromatic mixed solvents such as solvent naphtha. Examples of aromatic mixed solvents include "Swasol" (trade name, manufactured by Maruzen Oil Co., Ltd.) and "Ipsol" (trade name, manufactured by Idemitsu Kosan Co., Ltd.). One type of solvent may be used alone, or two or more types may be used in combination at any ratio.

[0065] [Other ingredients] The adhesive composition of the present invention may also contain, as needed, other additives such as an alkoxysilane compound, a heat-curing catalyst, inorganic oxide fine particles, an antioxidant, a surfactant, a storage stabilizer, a leveling agent, and a light stabilizer.

[0066] [Characteristics of adhesive composition] (melt viscosity) The adhesive composition preferably has a melt viscosity of 5 to 500 mPa·s. A melt viscosity of 500 mPa·s or less ensures sufficient adhesion to perovskite solar cells. A melt viscosity of 5 mPa·s or more makes it easier to expel air from recesses when attaching the adhesive to perovskite solar cells with a roller or similar tool, reducing the likelihood of voids forming. The melt viscosity can be measured, for example, using a rheometer (HAAKE MARS II (manufactured by Eiko Seiki Co., Ltd.)) with a gap of 500 μm, a sample diameter of 8 mm, a heating rate of 10°C / min, and a frequency of 1 Hz in the range of 25°C to 200°C.

[0067] (curing temperature) The curing temperature of the adhesive composition is preferably 60°C to 120°C. If the temperature is 120°C or lower, the perovskite layer is not destroyed and power generation efficiency is sufficient. If the temperature is 60°C or higher, the adhesive composition (such as a film) can be stored at room temperature, eliminating the need for refrigeration or freezing. If condensation occurs on the (film-like) adhesive composition during refrigeration or freezing, this can cause the perovskite layer to dissolve, but this problem does not occur with the above adhesive composition.

[0068] [Film-type sealing material] The film-like sealing material of the present invention comprises a dried product of the above adhesive composition, and is obtained by evaporating the diluent solvent from the adhesive composition of the present invention to dryness. The film-like encapsulating material of the present invention can be used as an adhesive, cohesive, and transparent adhesive or adhesive film, and can be widely used in fields such as paint, electrical engineering, automotive, and construction and building materials. It exhibits excellent low-temperature curing properties compared to conventional transparent resins. These properties allow it to maintain the power generation performance of perovskite solar cells before and after encapsulation, while maintaining low-temperature curing properties not possible with conventional transparent resin systems. Therefore, it can be used favorably.

[0069] (Method for producing film-like sealing material) The film-like encapsulant can be produced by a production method including forming a layer of encapsulant on a support, for example, by a method including preparing an adhesive composition (varnish) containing a encapsulant (adhesive) and a solvent, applying the varnish to a support, and drying the applied varnish (evaporating to dryness). The film-shaped sealing material can be produced, for example, as follows. A photoacid generator (UV-sensitive reaction initiator) is added to the 50% anisole varnish of the epoxy resin described above to obtain an anisole solution of the epoxy resin. This anisole solution of the epoxy resin is applied to a release PET film surface-treated with a silicone-based release agent using a bar coater. above The PET film coated with the epoxy resin adhesive is dried in a dryer (evaporated to dryness) to obtain an epoxy film sealing material having an adhesive layer of a predetermined thickness.

[0070] The varnish can be dried, for example, by heating or hot air blowing. There are no particular limitations on the drying conditions, and the temperature can be, for example, 50°C to 100°C. The drying time is preferably 1 minute or more, more preferably 3 minutes or more, and preferably 60 minutes or less, more preferably 15 minutes or less. After the varnish is applied to the support, the applied varnish is dried to remove the solvent (evaporate to dryness), and a layer of the sealing material is obtained on the support.

[0071] The method for producing a film-like encapsulating material may include heating the encapsulating material layer, if necessary. Heating can promote the reaction of reactive groups contained in the encapsulating material, thereby promoting reactions such as crosslinking and polymerization to an appropriate degree and increasing the hardness of the encapsulating material layer. This heating is suitable when a pressure-sensitive adhesive encapsulating material is used. This heating is particularly preferable when a pressure-sensitive adhesive encapsulating material containing a component having a reactive group such as an acid anhydride group or an epoxy group is used. Heating before encapsulation can prevent thermal degradation of the components contained in the encapsulated material. The heating conditions are not particularly limited. The heating temperature is preferably 50°C to 200°C, more preferably 100°C to 180°C, and even more preferably 120°C to 160°C. The heating time is preferably 15 to 120 minutes, more preferably 30 to 100 minutes.

[0072] The method for producing a film-like sealing material may include providing a protective film, if necessary. The protective film may be provided, for example, by laminating the protective film and the sealing material layer. When the sealing material layer is heated, the protective film may be provided before or after the sealing material layer is heated.

[0073] The film encapsulant may further contain residual solvent, but it is preferable that the amount of residual solvent in the film encapsulant be as small as possible, taking into consideration the properties of the encapsulant. The dilution solvents listed above can be residual solvents, but the residual amount per mass of the film encapsulant is preferably 5000 ppm or less, more preferably 3000 ppm or less, and particularly preferably 1000 ppm or less. If the residual solvent is within this range, it will not affect the JV characteristics of the perovskite solar cell. It is preferable that the film encapsulant further contains a residual solvent, the residual solvent being dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), and the residual amount per mass of the film encapsulant is 5000 ppm or less. When the residual solvent DMF or DMSO is contained in the adhesive layer in an amount of 5000 ppm or less, there is no particular adverse effect on the JV characteristics.

[0074] (How to use film-type sealing material) The film-like encapsulant can be used to encapsulate an object to be encapsulated, such as a perovskite layer or an electrode. A sealing method using the film-like encapsulant typically involves laminating a layer of the encapsulant to the object to be encapsulated. When the film-like encapsulant includes a protective film, the lamination is typically performed after peeling off the protective film. The lamination method may be a batch method or a continuous method using a roll.

[0075] Typically, in the above-mentioned lamination, a sealing material layer and a support are provided on the sealing target in this order. Therefore, the sealing target after lamination can be covered with the sealing material layer and the support. In a sealing method using a film-like sealing material, a state in which the sealing target is covered with the sealing material layer and the support may be obtained without peeling off the support. In this state, the sealing target is sealed not only by the sealing material layer but also by the support, so that moisture penetration can be effectively suppressed. For example, when using a film-like sealing material having a support with high moisture permeability resistance, such as a support having a barrier layer or a support having a metal foil, it is preferable to seal with the sealing material layer and the support as described above.

[0076] In a sealing method using a film-like sealing material, for example, the support may be peeled off after the lamination to obtain a state in which the sealing target is covered with a layer of sealing material. Even in this state, the layer of sealing material sealing the sealing target can effectively suppress moisture penetration. For example, when using a film-like sealing material having a support that does not have high moisture permeation resistance, such as a support that does not have a barrier layer or a support that does not have a metal foil, it is preferable to perform sealing with a layer of sealing material as described above.

[0077] The sealing method using the film-like sealing material may further include, for example, providing a sealing substrate. In particular, when peeling off the support as described above, it is preferable to provide a suitable sealing substrate on the surface of the sealing material layer exposed by peeling off the support. As such a sealing substrate, for example, the same film as the above-mentioned support may be used, or a rigid plate material such as a glass plate, a metal plate, or a steel plate may be used. By providing a sealing substrate, the intrusion of moisture can be more effectively suppressed.

[0078] The sealing method using a film-like sealing material may include, for example, curing the sealing material layer after lamination. Typically, heat is applied to the sealing material layer to promote reactions such as crosslinking and polymerization of reactive groups contained in the sealing material, thereby thermally curing the sealing material layer. This improves the adhesion between the sealing target and the sealing material and the mechanical strength of the sealing material layer, thereby enhancing the sealing ability of the sealing material. Therefore, moisture penetration and lead leakage can be particularly effectively suppressed. Such thermal curing after lamination is suitable when using a thermosetting sealing material.

[0079] During the thermal curing, the sealing material layer is usually heated using an appropriate heat treatment device. Examples of heat treatment devices include a hot air circulation oven, an infrared heater, a heat gun, and a high-frequency induction heating device. Alternatively, the sealing material layer may be heated by, for example, pressing a heat tool against the sealing material layer. From the viewpoint of enhancing adhesion between the sealing target and the sealing material layer, the curing temperature is preferably 50°C or higher, more preferably 55°C or higher, and particularly preferably 60°C or higher. Furthermore, from the viewpoint of suppressing thermal degradation of components contained in the sealing target, the curing temperature is preferably 150°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower. The curing time is preferably 10 minutes or longer, more preferably 20 minutes or longer.

[0080] In any of the above-described sealing methods, sealing is achieved by a layer of sealing material. Therefore, when the sealing target includes a lead-containing portion such as a perovskite layer, not only can the intrusion of water into the lead-containing portion be suppressed, but also the leakage of lead from the lead-containing portion can be suppressed.

[0081] The adhesive composition and film-like sealing material of the present invention can be photocured as described below, so heating (e.g., 60-120°C / 60 seconds) for curing is not required. However, heat may be applied as needed to transfer them to a substrate (e.g., glass). Softening them with heat allows them to adhere to the other substrate (e.g., glass), and the support film can then be peeled off by returning them to room temperature. The transfer temperature to the other substrate is, for example, 60-120°C, preferably 80-100°C. The transfer time is 10-180 seconds, preferably 30-120 seconds. They can then be cured by light irradiation.

[0082] The adhesive composition and film-like sealing material of the present invention contain a UV-sensitive initiator and are photocurable. For example, they can be cured by light irradiation even at low temperatures, such as room temperature (25°C). The photocuring conditions can be set depending on the components of the composition, such as the UV-sensitive initiator. For example, they can be cured by irradiating them with 365 nm ultraviolet light at 460 mW / cm. 2 , 3000mJ / cm 2 The irradiation conditions for photocuring are, for example, 200-3000mW / cm 2 , preferably 300-1000mW / cm 2 is.

[0083] The adhesive composition and film-like sealing material of the present invention cure at low temperatures and exhibit good adhesive force (adhesive strength). The adhesive strength can be evaluated as follows. First, an adhesive composition (epoxy resin composition) was prepared. The epoxy resin composition was applied to a 50 μm-thick PET film (LS-2, manufactured by Nippa Corporation) with a release agent to a thickness of 20 μm, and then dried at 100°C for 10 minutes to volatilize the solvent, yielding a two-layer film of PET-epoxy resin composition. Next, the two-layer film of PET-epoxy resin composition was placed on an alumina substrate with the epoxy resin composition side facing each other, and heated (60-120°C, 60 seconds each) and pressurized (0.1 atm) in a vacuum laminator to bond the epoxy resin composition to the alumina substrate. After cooling to room temperature, the PET film was peeled off to expose the epoxy resin composition layer. Five pieces of glass measuring 5 mm x 5 mm x 1 mm were placed on the epoxy resin composition layer, and then exposed to ultraviolet light (365 nm, 460 mW / cm 2 ) to harden the adhesive, and prepare an adhesive test piece. The adhesive strength at the time of cutting is measured using a die bond tester (device name: DageSeries4000 Bondtester, test speed: 200μm / s, test height: 10.0μm, measurement temperature: 25℃). [Example]

[0084] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts refer to parts by mass. In addition, in the synthesis examples, "(total number of moles of epoxy groups) / (number of moles of acid anhydride)" is the ratio of the total number of moles of epoxy groups in the difunctional epoxy resin and the trifunctional or higher epoxy resin (total number of moles of epoxy groups) to the number of moles of saturated acid anhydride (number of moles of acid anhydride), and the "difunctional epoxy resin ratio" is the value of (number of moles of difunctional epoxy resin) / [(number of moles of difunctional epoxy resin)+(number of moles of trifunctional or higher epoxy resin)].

[0085] (Examples 1-3, Comparative Example 1) [Synthesis Example 1] A 1 L separable flask equipped with a reflux condenser, a thermometer, a 25 ml water content receiver with a stopcock, a thermometer, and a stirrer was charged with 19.70 parts of BisA epoxy resin JER-1001 (Mitsubishi Chemical Corporation), 31.89 parts of triazine ring-type trifunctional epoxy resin TEPIC-S (Nissan Chemical Co., Ltd.), and 48.41 parts of Rikacid MH (New Japan Chemical Co., Ltd.). The mixture was stirred at 90 °C for 150 minutes to synthesize an epoxy-rich polymer. To this mixture, 100 parts of anisole was added to prepare an epoxy anisole solution. The ratio (moles of total epoxy groups) / (moles of acid anhydride) was 1.27, and the bifunctional epoxy resin ratio was 0.17.

[0086] [Synthesis Example 2] An epoxy-rich polymer was synthesized by adding 1.45 parts of BisA epoxy resin JER-1001 (Mitsubishi Chemical Corporation), 30.27 parts of triazine ring-type trifunctional epoxy resin TEPIC-S (Nissan Chemical Corporation), and 48.91 parts of Rikacid MH (New Japan Chemical Co., Ltd.) to a 1 L separable flask equipped with a reflux condenser, a thermometer, and a stirrer. The mixture was stirred at 90°C for 150 minutes to synthesize the epoxy-rich polymer. Then, 19.37 parts of TEPIC-S (Nissan Chemical Corporation) and 100 parts of anisole were added to prepare an epoxy-anisole solution. The ratio (moles of total epoxy groups) / (moles of acid anhydride) was 1.73, and the bifunctional epoxy resin ratio was 0.096.

[0087] [Synthesis Example 3] An epoxy-rich polymer was synthesized by adding 1.45 parts of BisA epoxy resin JER-1001 (Mitsubishi Chemical Corporation), 49.64 parts of triazine ring-type trifunctional epoxy resin TEPIC-S (Nissan Chemical Corporation), and 48.91 parts of Rikacid MH (New Japan Chemical Co., Ltd.) to a 1 L separable flask equipped with a reflux condenser, a stopcock, a thermometer, and a stirrer. The mixture was stirred at 90 °C for 150 minutes. Another 19.37 parts of TEPIC-S (Nissan Chemical Corporation) and 100 parts of anisole were added. Then, 0.3 parts of KBM-803 (3-mercaptopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd.) were added to the epoxy-rich polymer. The mixture was stirred at 75 °C for 120 minutes to synthesize an alkoxysilane-added epoxy-rich polymer. 100 parts of anisole was added to this to prepare an epoxy anisole solution. The ratio (total number of moles of epoxy groups) / (number of moles of acid anhydride) was 2.41, and the bifunctional epoxy resin ratio was 0.069.

[0088] [Production Example 1] A perovskite solar cell was fabricated using the method described below. [MAPbI3·DMF complex] A solution of PbI2 (2.305 g, 5.0 mmol) and methylammonium iodide (MAI; CH3NH3I; 795 mg, 5.0 mmol) in dimethylformamide (DMF; 5.0 mL, equivalent to 1.0 M MAPbI3) was placed in a screw cap tube. A few drops of DMF were placed on top of the solution as a cushion layer, allowing them to drip down the wall of the screw cap tube. A poor solvent (toluene) was slowly added on top of the solution, ensuring a 1:1 volume ratio between the DMF layer and the poor solvent layer. The container was then capped and allowed to stand at room temperature. The solvent diffused over approximately one day, resulting in the formation of colorless needle-like crystals. The crystals were collected by filtration and dried under reduced pressure at room temperature for 20 minutes, yielding 3.167 g (94% yield) of needle-like crystals. A 1.55M DMF solution of the crystals obtained above (before filtering and drying) and MAI dissolved in a 1:1 molar ratio was spin-coated onto the mesoporous TiO2 layer in an amount of 200 μL (per 2.5 cm square electrode). Three seconds before the end, 450 μL of toluene was added over two seconds. The resulting transparent film was immediately heated below 100°C for 30 minutes, and then heated at 100°C for 30 minutes (annealing treatment), yielding the highly pure perovskite material MAPbI3.

[0089] Precursor solution: The MAPbI3·DMF complex (1040 mg, 1.5 mmol) obtained in Preparation Example 1 was weighed out and dried at 60°C and 30 mmHg under reduced pressure for 4 hours. The resulting complex was then added to 1 mL of DMSO and dissolved by stirring for 2 minutes.

[0090] The solar cell characteristics of the perovskite solar cell obtained using the precursor solution were measured.

[0091] Perovskite solar cells A patterned transparent conductive glass substrate (FTO, 25 mm × 25 mm, Asahi Glass Co., Ltd., Japan) was ultrasonically cleaned in a 1% by weight neutral detergent solution, acetone, 2-propanol, and distilled water, for 10 minutes each, and finally, UV ozone cleaning for 15 minutes.

[0092] One mL of titanium di(isopropoxide)bis(acetylacetonate) (Ti(OiPr)2(acac)2, 75% by mass solution in 2-propanol, Tokyo Chemical Industry Co., Ltd., Japan) was added to 39 mL of ethanol (Wako, ultra-dehydrated). The above FTO substrate (transparent electrode) was placed on a hot plate at 450 °C and sprayed with the Ti(OiPr)2(acac)2 solution (carrier gas: N2, 0.5 MPa) to form a compact TiO2 layer (approximately 30 nm). The resulting substrate was then immersed in 100 mL of an aqueous solution of TiCl4 (440 μL, special grade, Wako Pure Chemical Industries Ltd., Japan) at 70 °C for 30 min. The substrate was then baked at 500 °C for 20 min to form a hole-blocking layer.

[0093] Approximately 190 μL (per 2.5 cm square electrode) of an ethanol solution (paste:ethanol = 1:8 (mass ratio)) of TiO paste (PST-18NR, JGC Catalysts and Chemicals Ltd.) was spin-coated onto the resulting compact TiO layer ((hole) blocking layer) to form a mesoporous TiO layer (electron transport layer) with a thickness of approximately 100 to 150 nm.

[0094] The substrate, on which the mesoporous TiO2 layer (electron transport layer) had just been formed and treated with UV ozone, was placed in a glove box. A solution was prepared by adding a mixed solvent of DMF and DMSO (volume, 3:1) to a 1:1 (molar ratio) mixture of PbI2 and MAI to a concentration of 1.5 M. After adding and dissolving MAI, approximately 250 μL of this solution (per 2.5 cm square electrode) was applied to the mesoporous TiO2 layer (electron transport layer). ) coatingThe film was then annealed at 40°C for 5 minutes, 55°C for 5-30 minutes, and then 75°C for 5 minutes, followed by 100°C for 30 minutes, to produce a smooth, dense perovskite layer approximately 500 nm thick.

[0095] A hole-transporting material (Spiro-OMeTAD; 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene, 61.3 mg, 0.050 M), [tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tris(bis(trifluoromethylsulfonyl)imide)] (FK209; 11.3 mg, 0.0075 M) and 4-tert-butylpyridine (TBP; 24.4 μL, 0.165 M, Aldrich), and lithium bis(trifluoromethylsulfonyl)imide (LITFSI; 7.6 mg, 0.027 M, Wako Pure Chemical Industries Co., Ltd.) were dissolved in 1 mL of chlorobenzene. After stirring for 30 min, the solution was filtered through a membrane filter, and the filtrate was spin-coated onto the perovskite layer. The obtained substrate was annealed at 70°C for 30 minutes to form a hole transport layer (approximately 200 nm), and then an 80 nm gold electrode was attached on the hole transport layer by vacuum deposition to obtain a perovskite solar cell.

[0096] The methods for preparing the epoxy film encapsulant and the epoxy resin-encapsulated perovskite solar cell test pieces, and the methods for measuring viscosity and adhesive force (adhesion strength) are as follows.

[0097] [Method for producing epoxy film encapsulant] 2.5 parts of San-Apro CPI-300 was added to 200 parts of the 50% anisole varnish of the epoxy resin described above, and the epoxy resin anisole solution was applied using a bar coater to a release PET film that had been surface-treated with a silicone release agent. aboveThe PET film coated with the epoxy resin adhesive was dried in a dryer at 100°C for 10 minutes to obtain an epoxy film-like sealing material (adhesive) with a 20 μm adhesive layer.

[0098] [Method for preparing epoxy resin-encapsulated perovskite solar cell test specimens] The epoxy resin-encapsulated perovskite solar cell test specimen of the present invention was prepared by vacuum laminating the above-mentioned epoxy film-like encapsulant onto a perovskite solar cell test specimen at 80 or 100°C for 60 seconds, and then irradiating the specimen with a 365nm UV-LED at 460mW / cm at room temperature (25°C). 2 , 3000mJ / cm 2 The epoxy resin-encapsulated perovskite solar cell specimens were obtained.

[0099] [Viscosity measurement method] The viscosity of the varnish (epoxy anisole solution) obtained in the synthesis examples was measured in a thermostatic water bath at 25°C using an Ostwald viscometer.

[0100] [Adhesive strength] The epoxy resin compositions (epoxy anisole solutions) obtained in Synthesis Examples 1 to 3 were dissolved in anisole solvent to a solid content of 50%, and applied to a PET film coated with fluorosilicone using a bar coater to a thickness of 25 μm. The solvent was dried at 100°C for 10 minutes to obtain a 20 μm thick adhesive layer. This was then attached to a 5 mm x 5 mm x 725 μm quartz piece at 100°C for 60 seconds, and then sandwiched between a 30 mm x 75 mm x 2 mm glass test piece so that the quartz layer - epoxy layer - glass layer were formed. The adhesive layer was then heated at 100°C for 6 kgf / cm. 2 ,Compression in 60 seconds, 365nm UV-LED, 460mW / cm at room temperature (25℃) 2 , 3000mJ / cm 2 The epoxy resin layer was cured by irradiation. Adhesion test specimens were prepared in this manner. The shear adhesive strength was then measured at a speed of 0.5 mm / min using a Dage 4000 adhesion tester manufactured by Dage.

[0101] [JV characteristic evaluation method] The photoelectric conversion characteristics of the perovskite solar cells of the examples and comparative examples were measured in accordance with the JIS C 8913:2005 crystalline solar cell output measurement method. A solar simulator (OTENTO-SUNIII, manufactured by Bunkoukeiki) was combined with an AM1.5G air mass filter, and the light intensity of the measurement light source was 100 mW / cm using a reference solar cell. 2 was adjusted to. In actual measurements, the measurement area is 0.1 cm 2 The JV curve characteristics were measured using a source meter (Model 2400, manufactured by Keithley Instruments) while irradiating light onto a masked solar cell element so that the JV curve was 100%. From the results, the short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), series resistance (Rs), and parallel resistance (Rsh) were derived. Furthermore, the photoelectric conversion efficiency (PCE) was calculated using the following formula. Note that the initial PCE was determined for the above epoxy film encapsulant, and the post-encapsulation PCE was determined for the above epoxy resin-encapsulated perovskite solar cell test piece. PCE(%) = (Jsc(mA / cm 2 )×Voc(V)×FF / 100(mW / cm 2 ))×100

[0102] The results are shown in Table 1.

[0103] [Table 1]

[0104] In Examples 1-3, which used film-like encapsulants obtained from the adhesive compositions of the present invention (varnishes of Synthesis Examples 2 and 3), the compositions had low viscosity, could be cured at low temperatures, and had excellent adhesion, and the power generation performance of the perovskite solar cells was able to be maintained before and after encapsulation. On the other hand, in Comparative Example 1, which does not correspond to the present invention and in which the (total number of moles of epoxy groups) / (number of moles of acid anhydride) was less than 1.30 and the bifunctional epoxy resin ratio was more than 0.15, the composition had high viscosity and poor adhesion, and the power generation performance of the encapsulated perovskite solar cells was significantly reduced.

[0105] The present specification includes the following aspects. [1]: An adhesive composition comprising: (A) a reaction product of a difunctional epoxy resin represented by the following general formula (2), a tri- or higher functional epoxy resin represented by the following general formula (3), and a saturated acid anhydride represented by the following general formula (4); (B) a UV-sensitive reaction initiator; and (C) a diluent solvent, The component (A) is a compound represented by the following general formula (1): [ka] (In the formula, A is a saturated divalent hydrocarbon group. Each B is independently a group represented by general formula (1a) or general formula (1b). R2 is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Z is a single bond or an oxygen atom. k is an integer of 2 or more. * is a bond. The order of repeating unit l and repeating unit m in the formula is arbitrary.) [ka] (wherein R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (wherein A is the same as above.) The amounts of the bifunctional epoxy resin, tri- or higher functional epoxy resin, and saturated acid anhydride are such that the ratio of the total number of moles of epoxy groups in the bifunctional epoxy resin and tri- or higher functional epoxy resin to the number of moles of the saturated acid anhydride is 1.30 to 3.00, and the number of moles of the bifunctional epoxy resin relative to the total number of moles of the bifunctional epoxy resin and tri- or higher functional epoxy resin is 0.001 to 0.15. [2]: The adhesive composition according to [1], wherein the reaction product is a polymer obtained by polymerizing the bifunctional epoxy resin, the tri- or higher functional epoxy resin, and the saturated acid anhydride, and the weight-average molecular weight of the polymer is 2,000 to 20,000. [3]: The adhesive composition according to [1] or [2], characterized in that the component (A) further contains a reaction product represented by the following general formula (5), which is obtained by reacting the compound represented by the general formula (1) with an alkoxysilane compound represented by the following general formula (6) or a partial hydrolyzate thereof: [ka] [ka] (In the formula, A, R2, R3, Z, k, and * are the same as above. Each B' is independently a group represented by general formula (5a) or general formula (5b). Each Z' is independently R4(OR5)2Si- or a group derived from a partial hydrolyzate of an alkoxysilane compound represented by general formula (6). R4 is a monovalent organic group including a vinyl group, a styryl group, an acryl group, a methacryl group, an amino group, a mercapto group, a ureido group, or an isocyanate group, and R5 is a monovalent organic group including a methyl group, an ethyl group, a propyl group, or an isopropyl group.) [4]: The adhesive composition according to any one of [1] to [3], wherein the bifunctional epoxy resin is a BisA type epoxy resin represented by the following general formula (2'), the tri- or higher functional epoxy resin is a triazine ring type trifunctional epoxy resin represented by the following general formula (3'), and the saturated acid anhydride is a saturated hydrocarbon type acid anhydride represented by the following general formula (4'). [ka] (wherein n is an integer of 1 or more). [ka] [ka] [5]: A film-like sealing material comprising a dried product of the adhesive composition according to any one of [1] to [4]. [6]: The film-shaped encapsulating material according to [5], characterized in that the film-shaped encapsulating material further contains a residual solvent, the residual solvent being dimethylformamide and / or dimethyl sulfoxide, and the residual amount per mass of the film-shaped encapsulating material is 5000 ppm or less.

[0106] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. An adhesive composition comprising: (A) a reaction product of a difunctional epoxy resin represented by the following general formula (2), a tri- or higher functional epoxy resin represented by the following general formula (3), and a saturated acid anhydride represented by the following general formula (4); (B) a UV-sensitive reaction initiator; and (C) a diluent solvent, The component (A) is a compound represented by the following general formula (1): 【Chemistry 1】 (In the formula, A is a saturated divalent hydrocarbon group. Each B is independently a group represented by general formula (1a) or general formula (1b). R ２ R is a substituted or unsubstituted divalent organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. ３ is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocyclic ring. Each Z is independently a single bond or an oxygen atom. k is an integer of 2 or more. * is a bond. The order of repeating unit l and repeating unit m in the formula is arbitrary. 【Chemistry 2】 (In the formula, R ２ , Z is the same as above.) 【Transformation 3】 (In the formula, R ３ , Z, and k are the same as above.) 【Chemistry 4】 (In the formula, A is the same as above.) The component (A) further contains a reaction product represented by the following general formula (5), which is obtained by reacting the compound represented by the general formula (1) with an alkoxysilane compound represented by the following general formula (6) or a partial hydrolyzate thereof: 【Transformation 5】 【Transformation 6】 (In the formula, A, R 2 , R 3 , Z, k, and * are the same as above. Each B' is independently a group represented by general formula (5a) or general formula (5b). Each Z' is independently R 4 (OR 5 ) 2 Si— or a group derived from a partial hydrolyzate of an alkoxysilane compound of general formula (6). R 4 is a monovalent organic group including a vinyl group, a styryl group, an acryl group, a methacryl group, an amino group, a mercapto group, a ureido group, or an isocyanate group, and R 5 is a monovalent organic group including a methyl group, an ethyl group, a propyl group, or an isopropyl group.) The amounts of the bifunctional epoxy resin, tri- or higher functional epoxy resin, and saturated acid anhydride are such that the ratio of the total number of moles of epoxy groups in the bifunctional epoxy resin and tri- or higher functional epoxy resin to the number of moles of the saturated acid anhydride is 1.30 to 3.00, and the number of moles of the bifunctional epoxy resin relative to the total number of moles of the bifunctional epoxy resin and tri- or higher functional epoxy resin is 0.001 to 0.

15.

2. 2. The adhesive composition according to claim 1, wherein the reaction product is a polymer obtained by polymerizing the bifunctional epoxy resin, the tri- or higher functional epoxy resin, and the saturated acid anhydride, and the polymer has a weight average molecular weight of 2,000 to 20,000, the weight average molecular weight being measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and expressed in terms of standard polystyrene.

3. 2. The adhesive composition according to claim 1, wherein the bifunctional epoxy resin is a BisA type epoxy resin represented by the following general formula (2'), the tri- or higher functional epoxy resin is a triazine ring type trifunctional epoxy resin represented by the following general formula (3'), and the saturated acid anhydride is a saturated hydrocarbon type acid anhydride represented by the following general formula (4'): 【Transformation 7】 (In the formula, n is an integer of 1 or more.) 【Transformation 8】 【Chemistry 9】

4. A film-like sealing material comprising a dried product of the adhesive composition according to any one of claims 1 to 3.

5. The film-shaped sealing material described in claim 4, characterized in that the film-shaped sealing material further contains a residual solvent, the residual solvent being dimethylformamide and / or dimethyl sulfoxide, and the residual amount per mass of the film-shaped sealing material is 5000 ppm or less.

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