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] With the recent increase in demand for renewable energy, there is 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 film-type transparent solar cells that can be applied to large areas so that they can be attached to the walls and windows of buildings. In order to realize such transparent film-type solar cells, there is a demand for adhesives that have low viscosity, low-temperature curing, high adhesion, and high reliability before and after sealing (Patent Document 1).

[0003] Conventionally, adhesive compositions of epoxy resin and saturated hydrocarbon acid anhydride have excellent low viscosity and high transparency, but are difficult to cure at low temperatures applicable to perovskite solar cells, and therefore have poor ability to maintain power generation performance before and after sealing. Therefore, simple adhesive compositions of epoxy resin and saturated hydrocarbon acid anhydride are uncured and suffer a significant decrease in power generation performance, making them unsuitable for use as adhesive compositions or film-like sealing materials for solar cells. [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 sealing material which have low viscosity, low temperature curing properties, high adhesion, and which maintain the power generation performance of perovskite-type solar cells before and after sealing. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides 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 dilution 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 heterocycle. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocycle. 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] (In the formula, R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (In the formula, A is the same as above.) The amount of the difunctional epoxy resin, tri- or higher functional epoxy resin, and saturated acid anhydride is 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 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.

[0007] Such an adhesive composition is a highly reliable epoxy resin-based 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 tri- or higher functional 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-mentioned 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) 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.)

[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] (In the formula, n is an integer of 1 or more.) [ka] [ka]

[0013] With such an adhesive composition, the above-mentioned 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 above 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] It is preferable that the film-like sealing material further contains a residual solvent, the residual solvent being dimethylformamide and / or dimethylsulfoxide, and the residual amount per mass of the film-like sealing material is 5000 ppm or less.

[0017] If the residual solvent dimethylformamide or dimethyl sulfoxide is contained in the adhesive layer at 5000 ppm or less, there is no particular adverse effect on the JV characteristics. Effect of the Invention

[0018] The adhesive composition and film-like sealing material of the present invention can be used as adhesive, cohesive, and transparent adhesives and adhesive films, and can be widely used in the fields of paints, electricity, automobiles, architecture and building materials, etc. Compared to conventional transparent resins, it exhibits excellent low-temperature curing properties in particular. Due to this property, it can be suitably used because it maintains low-temperature curing properties and the power generation performance of perovskite solar cells before and after sealing, which could not be achieved with conventional transparent resin systems. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present inventors have conducted intensive research to overcome the above-mentioned conventional shortcomings, and as a result, not only the reaction form of epoxy resin and saturated hydrocarbon-type acid anhydride, but also, for example, a triazine ring-containing trifunctional epoxy resin is contained, and a predetermined amount of triazine ring-containing trifunctional epoxy resin is contained in BisA-type epoxy resin to construct a three-dimensional polymer structure, thereby realizing high adhesion. An excessive amount of epoxy content is mixed with saturated hydrocarbon-type acid anhydride to prepare an oligomer, thereby realizing a film-like composition. In addition, an excessive amount of epoxy content is mixed with saturated hydrocarbon-type acid anhydride, and the epoxy content is set within a predetermined range to obtain a low-viscosity film-like composition. In addition, an alkoxysilane partial hydrolyzate is mixed to realize high adhesion to glass, and the above-mentioned epoxy resin adhesive composition (film-like adhesive composition) of the present invention has the properties of providing good performance of low viscosity, high adhesion, low-temperature curing, and maintaining the power generation performance of perovskite-type solar cells before and after sealing, and the present invention has been made.

[0020] That is, the present invention provides 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 dilution 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 heterocycle. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocycle. 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] (In the formula, R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (In the formula, A is the same as above.) 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 moles of epoxy groups in the bifunctional epoxy resin and the trifunctional or higher functional epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the moles of the bifunctional epoxy resin to the total moles of the bifunctional epoxy resin and the 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 a film-like encapsulant which have low viscosity, low temperature curing properties, high adhesion, and which 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 bifunctional epoxy resin, a trifunctional or higher epoxy resin, and a saturated acid anhydride, (B) a UV-sensitive reaction initiator, and (C) a dilution solvent, and the amount of the bifunctional epoxy resin, the trifunctional or higher epoxy resin, and the saturated acid anhydride is such that the ratio of the total moles of the epoxy groups of the bifunctional epoxy resin and the trifunctional or higher epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the moles of the bifunctional epoxy resin to the total moles of the bifunctional epoxy resin and the trifunctional or higher epoxy resin is 0.001 to 0.15. In addition to the above components (A) to (C), other components may be included as necessary. The adhesive composition of the present invention may also be in the form of a film (film-like adhesive composition). The components of the adhesive composition of the present invention will now be described.

[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 is arbitrary in the formula.

[0026] [ka] (In the formula, R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (In the formula, 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 trifunctional or higher functional epoxy resin, and a saturated acid anhydride (saturated hydrocarbon acid anhydride), and has an epoxy residue of a difunctional epoxy and an epoxy residue of a trifunctional or higher functional epoxy in the skeleton.

[0028] In the synthesis of component (A), specific compounds (difunctional epoxy resin, trifunctional or higher epoxy resin, saturated acid anhydride) described later are reacted in an amount such that the ratio of the total moles of epoxy groups in the difunctional epoxy resin and trifunctional or higher epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the moles of the difunctional epoxy resin to the total moles of the difunctional epoxy resin and trifunctional or higher 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, and more preferably 100 to 500 g / eq.

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

[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; diglycidyl ethers of resorcin, and 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 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. Further examples include divalent epoxy resins such as epoxy novolacs (i.e., novolac-type epoxy resins) obtained by condensing a novolac-type phenolic resin (or a halogenated novolac-type phenolic resin) such as phenol novolac or 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, preferred as the component of general formula (2) are bisphenol F type epoxy resins and bisphenol A type epoxy resins, which are liquid at room temperature.

[0034] Commercially available products may 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 either individually or in combination of two or more.

[0036] <Epoxy resin with three or more functional groups> The trifunctional or higher 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 heterocycle. Z is a single bond or an oxygen atom. k is an integer of 2 or more, preferably 2. [ka]

[0037] Examples of epoxy resins having three or more functionalities include glycidylamine type epoxy resins, heterocyclic epoxy resins, and aromatic or aliphatic epoxy resins having three or more functionalities. Examples of heterocyclic epoxy resins include epoxy resins having a heterocycle such as a triazine skeleton. Examples of aromatic epoxy resins having three or more functionalities include epoxy resins of polyhydric phenols, and examples of aliphatic epoxy resins having three or more functionalities include epoxy resins of polyhydric alcohols.

[0038] (Glycidylamine type epoxy resin) Examples of the glycidylamine type epoxy resin include diaminodiphenylmethane type epoxy resins such as tetraglycidyldiaminodiphenylmethane, diaminodiphenylsulfone type epoxy resins such as tetraglycidyldiaminodiphenylsulfone, tetraglycidylmetaxylenediamine, tetraglycidyl1,3-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 Co., Ltd.), 4-(glycidyloxy)-N,N-diglycidylaniline, 3-(glycidyloxy)-N,N-diglycidylaniline, and the like.

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

[0040] (Heterocyclic epoxy resin) As the heterocyclic epoxy resin, for example, triazine derivative epoxy resin such as 1,3,5-triazine nucleus derivative epoxy resin is preferably mentioned. In particular, epoxy resin having an isocyanurate ring has excellent light resistance and electrical insulation properties, and it is preferable that one has a divalent epoxy group per isocyanurate ring, and more preferably that one has a trivalent epoxy group. Specific examples of such heterocyclic epoxy resin include triglycidyl isocyanurate (product name TEPIC-S, Nissan Chemical Industries, Ltd.).

[0041] (Aromatic or aliphatic epoxy resins 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 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, 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. Further, specific examples of trifunctional or higher aromatic epoxy resins include tetrafunctional naphthalene type epoxy resin (product name Epiclon HP-4700, DIC Corporation), triphenylmethane type epoxy resin (product name 1032H60, Mitsubishi Chemical Corporation), and the like.

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

[0043] The acid anhydride of the epoxy resin curing agent is not particularly limited as long as it is a saturated acid anhydride.Saturated acid anhydrides include, for example, succinic anhydride, methyl succinic acid, ethyl succinic acid, 2,2-dimethyl succinic acid, 3-oxabicyclo (3,1,0) hexane-2,4-dione, tetradecyl succinic acid, hexadecyl succinic acid, 2-octadecyl succinic acid, hexahydrophthalic acid, 3-methyl hexahydrophthalic acid, 4-methyl hexahydrophthalic acid, 3-ethyl hexahydrophthalic acid, 4-ethyl hexahydrophthalic acid and other hexahydrophthalic acids, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, bicyclo (2,2,2) octane-2,3-dicarboxyanhydride, norcantharidin, cantharidin, etc.

[0044] The saturated acid anhydride may be a commercially available product, such as 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, trifunctional or higher epoxy resin, and saturated acid anhydride are such that the ratio ((total number of moles of epoxy groups) / (number of moles of acid anhydride)) of the total number of moles of epoxy groups of the bifunctional epoxy resin and trifunctional or higher epoxy resin to the number of moles of the saturated acid anhydride (number of moles of acid anhydride) is 1.30 to 3.00, and the number of moles of the bifunctional epoxy resin to the total number of moles of the bifunctional epoxy resin and the trifunctional or higher epoxy resin is 0.001 to 0.15 (bifunctional epoxy resin ratio). By setting the ratio of each component within such a range, a highly reliable epoxy resin-based adhesive composition or film-like sealing material that has low viscosity, low temperature curing, high adhesion, and maintains the power generation performance of a perovskite solar cell before and after sealing can be obtained. On the other hand, if the ratio of (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 may deteriorate the moisture resistance of the cured product obtained, or may be difficult to solidify at room temperature even if prepolymerized, resulting in poor adhesive strength after curing and a significant decrease in power generation performance. Also, if the ratio of (total number of moles of epoxy groups) / (number of moles of acid anhydride) exceeds 3.00, poor curing may occur and reliability may decrease. If the bifunctional epoxy resin ratio is less than 0.001 or exceeds 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] To synthesize the prepolymer, the above-mentioned bifunctional epoxy resin, trifunctional or higher epoxy resin, and saturated acid anhydride are mixed and reacted at 50 to 200°C, preferably 60 to 120°C, more preferably 70 to 110°C, for 1 to 20 hours, preferably 2 to 15 hours. The desired resin may be produced by adding each component described later, and the order of the components to be added may be any order. For example, when the bifunctional epoxy resin, trifunctional or higher epoxy resin, and saturated acid anhydride are mixed by heating, a part of the trifunctional or higher epoxy resin is first mixed by heating with the other components (first heating and mixing), and the remaining trifunctional or higher epoxy resin is added to the obtained reaction product and further mixed by heating (second heating and mixing) to obtain the desired reaction product. At this time, the temperature, stirring time, stirring means, etc. may be different between the first heating and mixing and the second heating and mixing. The above heating and mixing may be performed in the presence of a diluting solvent described later.

[0048] It is preferable that the reaction product contained in the adhesive composition of the present invention is a polymer obtained by polymerizing a difunctional epoxy resin, a trifunctional or higher epoxy resin, and a saturated acid anhydride, and that the weight average molecular weight of the polymer is 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 the adhesive strength is sufficient.

[0049] The weight average molecular weight is a weight average molecular weight calculated as standard polystyrene by GPC. The GPC measurement conditions are as follows: [Measurement conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.6mL / min Detector: Refractive index detector (RI) Column: TSK Guard 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 (THF solution with a concentration of 0.5% by mass)

[0050] <Alkoxysilane compounds and partial hydrolysates of alkoxysilanes> In the adhesive composition of the present invention, it is preferable that the component (A) further contains a reaction product represented by the following general formula (5) 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 a film-like adhesive composition) containing a reaction product represented by general formula (5) obtained by reacting a compound represented by general formula (1) with an alkoxysilane compound represented by general formula (6) or a partial hydrolysate 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 including at least one or more of the 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 hydrolysis condensation reaction of alkoxysilane 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 the partial hydrolysis condensate synthesized directly by hydrolysis condensation reaction of alkoxysilane containing one or more of the alkoxysilanes represented by general formula (6), but also the partial hydrolysis condensate synthesized by hydrolysis condensation reaction of alkoxysilane containing one or more of the alkoxysilanes represented by general formula (6) and then further hydrolysis condensation reaction. 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 a trifunctional alkoxysilane represented by the general formula (6) include (i) Wacker Asahi Kasei Corp.'s: 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 content 22% by weight)), KR9218 (containing methoxy, methyl and phenyl groups (methoxy content 15% by weight)), KR251, KR400, KR255, KR216, KR152, (iii) Dow Corning Toray Co., Ltd.: silicone resin: 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, methyl groups (methoxy content 36% by weight)), (containing oxetanyl groups and methyl groups (methoxy group content 33% by weight)), AY42-163 (Mw=4500, containing methoxy groups and methyl groups (methoxy group content 25% by weight)), (iv) silsesquioxane derivatives manufactured by Toagosei Co., Ltd., OX-SQ (containing oxetanyl groups (functional group equivalent: 263 g / eq)), OX-SQ-H (containing oxetanyl groups (functional group equivalent: 283 g / eq)), OX-SQSI-20 (containing oxetanyl groups (functional group equivalent: 262 g / eq)), AC-SQ (containing acryloyl groups (functional group equivalent: 165 g / eq)), and alkoxysilane partial hydrolysis condensates obtained by further hydrolysis and condensation reaction of these alkoxysilane partial hydrolysis condensates, etc.

[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 preferable that the difunctional epoxy resin is a BisA type epoxy resin represented by the following general formula (2'), the trifunctional or higher epoxy resin is a trifunctional triazine ring type 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'). Specifically, the BisA type epoxy resin can be JER-1001 (manufactured by Mitsubishi Chemical Corporation), the trifunctional triazine ring type epoxy resin can be TEPIC-S (manufactured by Nissan Chemical Industries, Ltd.), and the saturated hydrocarbon type acid anhydride can be Rikacid MH (manufactured by New Japan Chemical Co., Ltd.).

[0056] [ka] (In the formula, 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 reaction initiator (photocationic polymerization initiator) is required, which is a compound that initiates the polymerization of a resin by light, and any compound having such a function can be used without any particular limitation. A preferred example of the UV-sensitive reaction 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 X, 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, Br, etc. m is the net charge of the halide complex ion, and n is the valence of M.

[0060] In the 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 the 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, the curability is good, and if it is 10 mass % or less, the curability is excellent but the storage stability is poor.

[0064] [(C) component] The adhesive composition of the present invention contains a diluent solvent as component (C). As the dilution solvent, an organic solvent is usually used. 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" (manufactured by Maruzen Oil Co., Ltd., product name) and "Ipsol" (manufactured by Idemitsu Kosan Co., Ltd., product name). The solvent may be used alone or in combination of two or more types at any ratio.

[0065] [Other ingredients] The adhesive composition of the present invention may also contain, as necessary, other additives such as alkoxysilane compounds, heat-curing catalysts, inorganic oxide fine particles, antioxidants, surfactants, storage stabilizers, leveling agents, and light stabilizers.

[0066] [Characteristics of adhesive composition] (Melt Viscosity) The melt viscosity of the adhesive composition is preferably 5 to 500 mPa·s. If the melt viscosity is 500 mPa·s or less, the adhesive strength to the perovskite solar cell is sufficient. If the melt viscosity is 5 mPa·s or more, it becomes easy to expel air in the recesses when attaching the adhesive to the perovskite solar cell with a roller or the like, and voids are less likely to occur. The melt viscosity may 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 curing temperature is 120°C or lower, the perovskite layer is not destroyed and power generation efficiency is sufficient. If the curing temperature is 60°C or higher, the adhesive composition (film-like, etc.) can be stored at room temperature, eliminating the need for refrigerated or frozen storage. If condensation occurs on the (film-like) adhesive composition due to refrigerated or frozen storage, this can cause the perovskite layer to dissolve, but with the above adhesive composition, such a problem does not occur.

[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 encapsulant of the present invention can be used as an adhesive, cohesive, transparent adhesive and adhesive film, and can be widely used in the fields of paint, electricity, automobiles, architecture and building materials, etc. Compared to conventional transparent resins, it exhibits excellent low-temperature curing properties in particular. Due to these properties, it can be used favorably because it maintains the power generation performance of perovskite solar cells before and after encapsulation, and has low-temperature curing properties that could not be achieved with conventional transparent resin systems.

[0069] (Method of producing film-like sealing material) The film-like sealing material can be produced by a production method including forming a layer of a sealing material on a support. The layer of the sealing material can be formed by a method including, for example, preparing an adhesive composition (varnish) containing a sealing material (adhesive) and a solvent, applying the varnish onto 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 epoxy resin solution. This anisole epoxy resin solution is applied to a peelable PET film surface-treated with a silicone-based release agent using a bar coater. The PET film coated with the epoxy resin adhesive is dried in a dryer (evaporated to dryness) to obtain an epoxy film-like sealing material with an adhesive layer of a specified thickness.

[0070] The varnish can be dried, for example, by a heating method or a hot air blowing method. 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 onto 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 encapsulant may include heating the encapsulant layer as necessary. Heating can promote the reaction of reactive groups contained in the encapsulant, so that reactions such as crosslinking and polymerization can be promoted to an appropriate degree to increase the hardness of the encapsulant layer. This heating is suitable when a pressure-sensitive adhesive encapsulant is used. In particular, when a pressure-sensitive adhesive encapsulant containing a component having a reactive group such as an acid anhydride group and an epoxy group is used, the above-mentioned heating is preferably performed. Such heating before encapsulation can prevent thermal deterioration of the components contained in the encapsulation target. There are no particular limitations on the heating conditions. 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 minutes to 120 minutes, and more preferably 30 minutes to 100 minutes.

[0072] The method for producing a film-like sealing material may include providing a protective film as necessary. The protective film may be provided, for example, by laminating a protective film and a 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-shaped encapsulant may further contain a residual solvent, but it is preferable that the residual solvent in the film-shaped encapsulant is small in consideration of the properties of the encapsulant. The above-mentioned dilution solvents can be residual solvents, but the residual amount per mass of the film-shaped 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 such a range, it will not affect the JV characteristics of the perovskite solar cell. It is preferable that the film-like encapsulant further contains a residual solvent, the residual solvent being dimethylformamide (DMF) or dimethylsulfoxide (DMSO), and the residual amount per mass of the film-like 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 sealing material can be used for sealing objects such as perovskite layers and electrodes. A sealing method using a film-like sealing material usually includes laminating a layer of the film-like sealing material to an object to be sealed. When the film-like sealing material has a protective film, the lamination is usually performed after peeling off the protective film. The lamination method may be a batch method or a continuous method using a roll.

[0075] Usually, according to the lamination, a layer of a sealing material and a support are provided on the sealing target in this order. Therefore, the sealing target after lamination can be covered with the layer of a sealing material and the support. In the sealing method using a film-shaped sealing material, a state in which the sealing target is covered with the layer of a sealing material and the support may be obtained without peeling off the support. In this state, the sealing target is sealed not only by the layer of the sealing material but also by the support, so that the intrusion of moisture can be effectively suppressed. For example, when using a film-shaped 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 layer of a sealing material and the support as described above.

[0076] In the sealing method using the film-shaped 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 the sealing material. Even in this state, the layer of the sealing material sealing the sealing target can effectively suppress the intrusion of moisture. For example, when using a film-shaped sealing material having a support that does not have high moisture permeability resistance, such as a support having no barrier layer or a support having no metal foil, it is preferable to perform sealing with a layer of the sealing material as described above.

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

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

[0079] During the above-mentioned thermal curing, the layer of the sealing material is usually heated by an appropriate heat treatment device. Examples of the heat treatment device include a hot air circulation oven, an infrared heater, a heat gun, and a high-frequency induction heating device. In addition, the layer of the sealing material may be heated, for example, by pressing a heat tool against the layer of the sealing material. From the viewpoint of increasing the adhesion between the sealing target and the layer of the sealing material, the curing temperature is preferably 50°C or higher, more preferably 55°C or higher, and particularly preferably 60°C or higher. In addition, from the viewpoint of suppressing thermal deterioration of the 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 more, more preferably 20 minutes or more.

[0080] In any of the above-mentioned sealing methods, sealing by a layer of sealing material is achieved. Therefore, when the object to be sealed includes a lead-containing portion such as a perovskite layer, not only can the intrusion of moisture 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 (for example, 60-120°C / 60 seconds) for curing is not necessary, but heat may be applied as necessary to transfer them to a substrate (such as glass). By applying heat to soften them, they can be adhered to the other substrate (such as glass), and the support film can be peeled off by returning to room temperature after that. The transfer temperature to the other substrate is, for example, 60-120°C, preferably 80°C-100°C. The transfer time is 10-180 seconds, preferably 30-120 seconds. Then, they can be cured by light irradiation.

[0082] The adhesive composition and film-like sealing material of the present invention contain a UV-sensitive reaction initiator and can be photocured. For example, they can be cured by light irradiation at a low temperature of about room temperature (25°C). The photocuring conditions can be set according to the components of the composition, such as the UV-sensitive reaction initiator. For example, the adhesive composition and film-like sealing material can be cured by irradiating the composition 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 It is.

[0083] The adhesive composition and the film-like sealing material of the present invention are cured 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) is prepared. The epoxy resin composition is applied to a 50 μm-thick PET film (LS-2 manufactured by Nippa Corporation) with a release agent so that the thickness is 20 μm, and the film is dried at 100° C. for 10 minutes to evaporate the solvent, thereby obtaining a two-layer film of PET-epoxy resin composition. Next, the two-layer film of PET-epoxy resin composition is placed on an alumina substrate so that the epoxy resin composition side faces each other, and the two-layer film is heated (60-120° C., 60 sec each) and pressurized (0.1 atm) with a vacuum laminator to bond the epoxy resin composition and the alumina substrate together. After cooling to room temperature, the PET film is peeled off to expose the layer of the epoxy resin composition. Five pieces of glass measuring 5 x 5 x 1 mm on a side were placed on the epoxy resin composition layer, and then exposed to ultraviolet light (365 nm, 460 mW / cm 2 ) to harden the adhesive test piece, and prepare an adhesive test piece. The adhesive test piece is then cut and its adhesive force (adhesive strength) is measured using a die bond tester (device name: DageSeries4000 Bondtester, test speed: 200μm / s, test height: 10.0μm, measurement temperature: 25℃). EXAMPLES

[0084] The present invention will be specifically described 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 (total number of moles of epoxy groups) of a bifunctional epoxy resin and a trifunctional or higher epoxy resin to the number of moles of saturated acid anhydride (number of moles of acid anhydride), and the "bifunctional epoxy resin ratio" is the value of (number of moles of bifunctional epoxy resin) / [(number of moles of bifunctional epoxy resin)+(number of moles of trifunctional or higher epoxy resin)].

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

[0086] [Synthesis Example 2] In a 1L separable flask equipped with a 25ml water content receiver with a stopcock connected to a reflux condenser, a thermometer, and a stirrer, 1.45 parts of BisA type epoxy resin JER-1001 (manufactured by Mitsubishi Chemical Corporation), 30.27 parts of triazine ring type trifunctional epoxy resin TEPIC-S (manufactured by Nissan Chemical Co., Ltd.), and 48.91 parts of Rikacid MH (manufactured by New Japan Chemical Co., Ltd.) were added at 90°C for 150 minutes with stirring to synthesize an epoxy-rich polymer. Then, 19.37 parts of TEPIC-S (manufactured by Nissan Chemical Co., Ltd.) were added again, followed by 100 parts of anisole to prepare an epoxy anisole solution. The ratio of (total number of moles of epoxy groups) / (number of moles of acid anhydride) was 1.73, and the ratio of bifunctional epoxy resins was 0.096.

[0087] [Synthesis Example 3] An epoxy-rich polymer was synthesized by carrying out a reaction with stirring for 150 minutes at 90 ° C. for 150 minutes, with 1.45 parts of BisA type epoxy resin JER-1001 (manufactured by Mitsubishi Chemical Corporation), 49.64 parts of triazine ring type trifunctional epoxy resin TEPIC-S (manufactured by Nissan Chemical Co., Ltd.), and 48.91 parts of Rikacid MH (manufactured by New Japan Chemical Co., Ltd.) in a 1 L separable flask equipped with a 25 ml water content receiver with a stopcock connected to a reflux condenser, a thermometer, and a stirrer. 19.37 parts of TEPIC-S (manufactured by Nissan Chemical Co., Ltd.) and then 100 parts of anisole were added again, and then 0.3 parts of KBM-803 (3-mercaptopropyltrimethoxysilane: manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this epoxy-rich polymer, and the reaction was carried out with stirring for 120 minutes at 75 ° C. to synthesize an epoxy-rich polymer to which alkoxysilane was added. 100 parts of anisole was added to this to prepare an epoxy anisole solution. (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] [Preparation Example 1] A perovskite solar cell was fabricated by 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) dissolved in dimethylformamide (DMF; 5.0 mL, equivalent to MAPbI3; 1.0 M) was poured into a screw tube. A few drops of DMF were placed on the solution as a cushion layer, running down the wall of the screw tube. A poor solvent (toluene) was slowly poured on top of this, so that the volume ratio of the DMF layer to the poor solvent layer was 1:1, and the container was covered and left to stand at room temperature. The solvent diffused in about a day, and colorless needle-like crystals were formed. 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 on the mesoporous TiO2 layer at 200μL (per 2.5cm square electrode), and 3 seconds before the end, 450μL of toluene was added for 2 seconds. The resulting transparent film was immediately heated below 100℃ for 30 minutes, and then heated at 100℃ for 30 minutes (annealing treatment), to obtain MAPbI3, a high-purity perovskite material.

[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 for 4 hours under reduced pressure. The 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 above precursor solution were measured.

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

[0092] 1 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 substrates (transparent electrodes) were arranged on a hot plate at 450 °C, and the Ti(OiPr)2(acac)2 solution was sprayed (carrier gas: N2, 0.5 MPa) to fabricate a compact TiO2 layer (approximately 30 nm). Furthermore, the obtained substrate was 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 minutes. The substrate was then baked at 500 °C for 20 minutes 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 TiO2 paste (PST-18NR, JGC Catalysts and Chemicals Ltd.) was spin-coated onto the obtained compact TiO2 layer ((hole) blocking layer) to form a mesoporous TiO2 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 prepared by UV ozone treatment was placed in a glove box. A solution was prepared by adding a mixed solvent of DMF and DMSO (Vol, 3:1) to a mixture of PbI2 and MAI in a 1:1 (molar ratio) solution to a concentration of 1.5M. After adding and dissolving MAI, this solution was applied to the substrate in an amount of about 250μL (per 2.5cm square electrode) on the mesoporous TiO2 layer (electron transport layer), spin-coated, and 0.5mL of toluene was dropped during the spin-coating to obtain a transparent film (slope was set to 5000rpm for 5 seconds, toluene was dropped in the final 1 second of the spin-coating for another 5 seconds, and the slope was stopped at 5 seconds). The resulting film was annealed at 40 °C for 5 min, 55 °C for 5–30 min, then 75 °C for 5 min, followed by 100 °C for 30 min to produce a flat and dense perovskite layer approximately 500 nm thick.

[0095] A hole transport 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 on 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 the viscosity and adhesive force (adhesive strength) are as follows.

[0097] [Epoxy film sealant manufacturing method] 2.5 parts of CPI-300 manufactured by San-Apro Co., Ltd. were added to 200 parts of the 50% anisole varnish of the epoxy resin described above, and the epoxy resin anisole solution was applied to a peelable PET film surface-treated with a silicone-based release agent using a bar coater. The 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 20μm 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 solar cell with a 365 nm UV-LED and 460 mW / cm at room temperature (25°C). 2 , 3000mJ / cm 2 The epoxy resin-encapsulated perovskite solar cell test specimen was 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 so that the solid content was 50%, and applied to a PET film coated with fluorosilicone to a thickness of 25 μm using a bar coater. The solvent was dried at 100°C for 10 minutes to obtain an adhesive layer with a thickness of 20 μm. This was attached to a quartz piece of 5 mm x 5 mm x 725 μm at 100°C for 60 seconds, and then sandwiched between glass test pieces of 30 mm x 75 mm x 2 mm so that the layers were quartz layer-epoxy layer-glass layer, and then heated at 100°C, 6 kgf / cm 2 , 60 seconds compression, 365nm UV-LED, 460mW / cm at room temperature (25℃) 2, 3000mJ / cm 2 The epoxy resin layer was cured by irradiating the sample with light. Thus, the adhesive test piece was prepared. The shear adhesive strength was then measured at a speed of 0.5 mm / min using a Dage 4000 adhesive 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 by a method conforming to 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 (2400 model, Keithley Instruments) while irradiating the solar cell element masked so that the JV curve characteristics were measured. 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. The initial PCE was determined for the above epoxy film-like 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 a film-like encapsulant obtained from the adhesive composition of the present invention (varnishes of Synthesis Examples 2 and 3), the composition had a low viscosity, could be cured at a low temperature, had excellent adhesion, and was able to maintain the power generation performance of the perovskite solar cell before and after encapsulation. On the other hand, in Comparative Example 1, which does not correspond to the present invention and in which (total number of moles of epoxy groups) / (number of moles of acid anhydride) was less than 1.30 and the bifunctional epoxy resin ratio exceeded 0.15, the composition had a high viscosity and poor adhesion, and the power generation performance of the perovskite solar cell after encapsulation was significantly reduced.

[0105] The present specification includes the following aspects. [1]: An adhesive composition comprising: (A) a reaction product of a bifunctional 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 dilution 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 heterocycle. R3 is a substituted or unsubstituted trivalent or higher organic group, including an aliphatic hydrocarbon group, an aromatic ring, or a heterocycle. 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] (In the formula, R2 and Z are the same as above.) [ka] (In the formula, R3, Z, and k are the same as above.) [ka] (In the formula, A is the same as above.) 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 moles of epoxy groups in the bifunctional epoxy resin and the trifunctional or higher functional epoxy resin to the moles of the saturated acid anhydride is 1.30 to 3.00, and the moles of the bifunctional epoxy resin to the total moles of the bifunctional epoxy resin and the trifunctional or higher functional epoxy resin is 0.001 to 0.15. [2]: The adhesive composition according to [1], characterized in that the reaction product is a polymer obtained by polymerizing the difunctional 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], further comprising, as the component (A), a reaction product represented by the following general formula (5) obtained by reacting a 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.) [4]: The adhesive composition according to any one of [1] to [3], wherein 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] (In the formula, 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-like encapsulating material according to [5], further comprising a residual solvent, the residual solvent being dimethylformamide and / or dimethylsulfoxide, and the residual amount per mass of the film-like encapsulating material being 5000 ppm or less.

[0106] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in 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): 【Chemical 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.) 【Chemistry 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: 【Chemistry 5】 【Chemistry 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'): 【Chemistry 7】 (In the formula, n is an integer of 1 or more.) 【Chemistry 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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