TWI859255B - Adhesive sheet for device sealing - Google Patents

Abstract

The present invention provides an adhesive sheet for device sealing, which comprises a first peeling film and a second peeling film, and an adhesive layer sandwiched between the first peeling film and the second peeling film, and is characterized by satisfying the following conditions (I) and (II). The adhesive sheet for device sealing of the present invention comprises an adhesive layer and a peeling film having excellent adhesion at room temperature, and the peeling film has excellent peeling properties. Condition (I): The adhesive layer comprises a layer of one or more compounds having a cyclic ether group. Condition (II): The storage modulus of the adhesive layer at 23° C. is 9.5×10 ⁵ Pa or more and 3.0×10 ⁷ Pa or less.

Description

Adhesive sheet for device sealing

The present invention relates to an adhesive sheet for device sealing, which comprises an adhesive layer having excellent adhesion at room temperature (meaning 23°C, the same applies hereinafter) and a peeling film, wherein the peeling film has excellent peeling property.

In recent years, organic EL elements have attracted attention as light-emitting elements that can emit light with high brightness by low-voltage DC drive. However, organic EL elements have the problem that the light-emitting characteristics such as light-emitting brightness, light-emitting efficiency, and light-emitting uniformity are easily reduced over time. Oxygen and water vapor penetrate into the interior of the organic EL element, causing the electrode and organic layer to deteriorate, which is considered to be the cause of the above-mentioned problem of reduced light-emitting characteristics. Therefore, it is proposed to use an adhesive layer with excellent waterproof properties or an adhesive layer to form a sealing material to solve this problem.

For example, Patent Document 1 describes a sheet-shaped sealing material, which includes a specific epoxy resin, a specific cyclohexyl compound, a thermal cationic polymerization initiator, a photo-cationic polymerization initiator, and a specific sensitizer. The sealing material formed using the sheet-shaped sealing material described in Patent Document 1 has low oxygen permeability and water permeability and has good sealing performance. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 201895679

[The problem that the invention is trying to solve]

As described in Patent Document 1, a sheet sealant utilizing the reactivity of a cyclic ether group is suitable for use as a sealant forming material. However, some of these sheet sealants have poor adhesion at room temperature, and some require heating to soften the surface when attached to the sealed object. On the other hand, some sheet sealants that have good adhesion at room temperature have poor processability when attached. That is, when the sheet-like sealing material (hereinafter sometimes referred to as "adhesive layer") sandwiched between two peel films is cut into a predetermined shape, the adhesive layer is deformed due to the cutting of the punching knife, and the peel film cannot be peeled off efficiently because the adhesive adheres to the portion of the end of the peel film that has not been subjected to the peeling treatment (cut surface).

In view of the above situation, the object of the present invention is to provide an adhesive sheet for device sealing, which includes an adhesive layer having excellent adhesion at room temperature and a peeling film, and the peeling film has excellent peeling properties. [Means for solving the problem]

In order to solve the above problems, the inventors have conducted in-depth research on a sealing adhesive sheet comprising two peeling films and an adhesive layer sandwiched between the peeling films, wherein the adhesive layer is a compound containing a cyclic ether group. As a result, it was found that: (a) an adhesive layer having a storage modulus below a predetermined value at 23°C has excellent adhesion at room temperature, and (b) an adhesive sheet comprising an adhesive layer having a storage modulus above a predetermined value at 23°C and a peeling film has excellent peeling properties of the peeling film, and thus the present invention was completed.

Therefore, according to the present invention, the following adhesive sheets for sealing devices [1] to [10] are provided.

[1] An adhesive sheet for sealing a device, comprising a first release film and a second release film, and an adhesive layer sandwiched between the first release film and the second release film, wherein the adhesive sheet satisfies the following conditions (I) and (II): Condition (I): The adhesive layer comprises one or more compounds having a cyclic ether group; Condition (II): The adhesive layer has a storage modulus of 9.5×10 ⁵ Pa to 3.0×10 ⁷ Pa at 23°C. [2] The adhesive sheet for sealing a device as described in [1], wherein at least one of the compounds having a cyclic ether group is a liquid compound at 25°C. [3] The adhesive sheet for sealing a device as described in [2], wherein the content of the compound having a cyclic ether group and being liquid at 25°C is 53% by mass or more relative to the adhesive layer as a whole. [4] The adhesive sheet for sealing a device as described in [3], wherein the content of the compound having a cyclic ether group and being liquid at 25°C is 65% by mass or less relative to the adhesive layer as a whole. [5] The adhesive sheet for sealing a device as described in any one of [1] to [4], wherein the adhesive layer further includes a hardener, and at least one of the hardeners is a thermal cationic polymerization initiator. [6] The adhesive sheet for sealing a device as described in [5], wherein all of the hardeners are thermal cationic polymerization initiators. [7] The adhesive sheet for device sealing as described in [5] or [6], wherein at least one of the compounds having a cyclic ether group is a compound having a glycidyl ether group. [8] The adhesive sheet for device sealing as described in any one of [5] to [7], wherein at least one of the compounds having a cyclic ether group is a cyclopentane epoxy resin. [9] The adhesive sheet for device sealing as described in any one of [1] to [8], wherein the adhesive layer includes an adhesive resin, and at least one of the adhesive resins is an adhesive resin having a glass transition temperature (Tg) of 60°C or higher. [10] The device sealing adhesive sheet as described in any one of [1] to [9], wherein the storage modulus of the layer obtained by curing the adhesive layer at 90°C is 1×10 ⁸ Pa or more. [11] The device sealing adhesive sheet as described in any one of [1] to [10] is used to form a sealing material in an optical device. [Effects of the Invention]

According to the present invention, there is provided an adhesive sheet for device sealing, which includes an adhesive layer having excellent adhesion at room temperature and a peeling film, wherein the peeling film has excellent peeling properties.

The device sealing adhesive sheet of the present invention comprises a first peeling film and a second peeling film, and an adhesive layer sandwiched between the first peeling film and the second peeling film, and is characterized by satisfying the following conditions (I) and (II).

In the present invention, the "first peeling film" refers to a peeling film that is peeled off after the "second peeling film" when the device sealing adhesive sheet is used, and the "second peeling film" refers to a peeling film that is peeled off first when the device sealing adhesive sheet is used. Therefore, when the two peeling films have different peeling forces, the "first peeling film" generally refers to the one with a higher peeling force among the two peeling films, and the "second peeling film" refers to the one with a lower peeling force among the two peeling films. The so-called "adhesive layer" refers to a layer that is formed by coating a curable adhesive and has curability and adhesiveness. That is, the "adhesive layer" is a layer in an uncured state. In this specification, "a layer obtained by curing the adhesive layer" is sometimes referred to as an "adhesive cured material layer". This adhesive cured material layer is used as a sealant. In the present invention, "curing" means that the cyclic ether group contained in the adhesive layer reacts to increase the cohesion and storage modulus of this layer.

[Adhesive layer] (Compound having a cyclic ether group) The adhesive layer includes one or more compounds having a cyclic ether group (hereinafter sometimes referred to as "cyclic ether compound (A)"). By hardening the adhesive layer including the cyclic ether compound (A), a sealing material having high adhesive strength and excellent water vapor barrier properties can be formed.

The cyclic ether compound (A) refers to a compound having at least one, preferably two or more cyclic ether groups in the molecule. In the present invention, the cyclic ether compound (A) does not include a phenoxy resin described later.

The molecular weight of the cyclic ether compound (A) is generally 100 to 5,000, preferably 200 to 3,000. The cyclic ether equivalent of the cyclic ether compound (A) is preferably 50 to 1,000 g/eq, and more preferably 100 to 800 g/eq. By hardening the adhesive layer including the cyclic ether compound (A) having a cyclic ether equivalent within the above range, a sealing material having higher adhesive strength and better waterproofness can be formed more efficiently. In the present invention, the cyclic ether equivalent means the value obtained by dividing the molecular weight by the number of cyclic ether groups.

Examples of the cyclic ether group include oxirane (epoxy), oxadiazole (oxetanyl), tetrahydrofuranyl, tetrahydropyranyl, etc. Among them, from the perspective of forming a sealant with higher adhesion strength, oxirane or oxadiazole is preferred as the cyclic ether group, and oxirane is more preferred. Furthermore, for the same reason, the cyclic ether compound (A) preferably has two or more oxirane or oxadiazole groups in the molecule, and preferably has two or more oxirane groups in the molecule.

Examples of compounds having an ethylene oxide group in the molecule include aliphatic epoxides (excluding aliphatic epoxides), aromatic epoxides, aliphatic epoxides, etc. Examples of aliphatic epoxides include monofunctional epoxides such as glycidyl ethers of aliphatic alcohols and glycidyl esters of alkyl carboxylic acids; Examples of polyfunctional epoxides include polyglycidyl ethers of aliphatic polyols or epoxide adducts thereof and polyglycidyl esters of aliphatic long-chain polyacids.

Typical compounds of these aliphatic epoxy compounds include alkenyl glycidyl ethers such as allyl glycidyl ether; alkyl glycidyl ethers such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and C12-13 mixed alkyl glycidyl ether; 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol triglycidyl ether, trihydroxymethylpropane triglycidyl ether, sorbitol tetraglycidyl ether, dipentatriol hexaglycidyl ether, polyethylene glycol diglycidyl ether, and the like. Glycidyl ethers of polyols such as diglycidyl ethers of glycols and diglycidyl ethers of polypropylene glycol; polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyols such as propylene glycol, trihydroxymethylpropane, glycerol, etc.; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of higher aliphatic alcohols, glycidyl esters of higher fatty acids, epoxidized soybean oil, octyl epoxystearate, butyl epoxystearate, epoxidized polybutadiene; etc.

Furthermore, commercially available products can also be used as the aliphatic epoxy compound. Commercially available products include Denacol EX-121, Denacol EX-171, Denacol EX-192, Denacol EX-211, Denacol EX-212, Denacol EX-313, Denacol EX-314, Denacol EX-321, Denacol EX-411, Denacol EX-421, Denacol EX-512, Denacol EX-521, Denacol EX-61 1. Denacol EX-612, Denacol EX-614, Denacol EX-622, Denacol EX-810, Denacol EX-811, Denacol EX-850, Denacol EX-851, Denacol EX-821, Denacol EX-830, Denacol EX-832, Denacol EX-841, Denacol EX-861, Denacol EX-911, Denacol EX-941, Denacol EX-920, Denacol EX-931 (all manufactured by Nagase Chemtex); Epolite M-1230, Epolite 40E, Epolite 100E, Epolite 200E, Epolite 400E, Epolite 70P, Epolite 200P, Epolite 400P, Epolite 1500NP, Epolite 1600, Epolite 80MF, Epolite 100MF (all manufactured by Kyoeisha Chemical Co., Ltd.); ADEKA GLYCIROL ED-503, ADEKA GLYCIROL ED-503G, ADEKA GLYCIROL ED-506, ADEKA GLYCIROL ED-523T (the above are manufactured by ADEKA).

As aromatic epoxy compounds, there can be listed phenols having at least one aromatic ring, such as phenol, cresol, butylphenol, or mono/polyglycidyl ethers of phenols or epoxide adducts thereof; epoxides having aromatic heterocycles; etc. As typical compounds of these aromatic epoxy compounds, there can be listed bisphenol A, bisphenol F, or epoxide novolac resins of compounds to which epoxides are further added; mono/polyglycidyl ethers of aromatic compounds having two or more phenolic hydroxyl groups, such as resorcinol, hydroquinone, or o-catechin; phenyl dimethanol, phenyl diethanol, phenyl dibutyl alcohol, etc. having two Glycidyl ethers of aromatic compounds with alcoholic hydroxyl groups as above; Glycidyl esters of polybasic aromatic compounds with two or more carboxylic acids such as phthalic acid, terephthalic acid, trimellitic acid, etc., glycidyl esters of benzoic acid, styrene oxide or epoxy compounds of divinylbenzene; Epoxy compounds with triazine skeletons such as 2,4,6-tris(glycidyloxy)-1,3,5-triazine; etc.

Furthermore, commercially available products may be used as aromatic epoxy compounds. Commercially available products include Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, ONCOAT EX-1020, ONCOAT EX-1030, ONCOAT EX-1040, ONCOAT EX-1050, ONCOAT EX-1051, ONCOAT EX-1010, ONCOAT EX-1011, ONCOAT 1012 (all manufactured by Nagase Chemtex Co., Ltd.); OGSOL PG-100, OGSOL EG-200, OGSOL EG-210, OGSOL EG-250 (manufactured by Osaka Gas Chemical Co., Ltd.); HP4032, HP4032D, HP4700 (manufactured by DIC Corporation); ESN-475V (manufactured by Nippon Steel Chemical & Material Corporation); JER YX8800 (manufactured by Mitsubishi Chemical Corporation); Marproof G-0105SA, Marproof G-0130SP (manufactured by NOF Corporation); Epiclon N-665, Epiclon HP-7200 (all manufactured by DIC); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501H, EPPN-501HY, EPPN-502H, NC-7000L (all manufactured by Nippon Kayaku); ADEKA Resin EP-4000, ADEKA Resin EP-4005, ADEKA Resin EP-4100, ADEKA Resin EP-4901 (all manufactured by ADEKA); TECHMORE VG-3101L (all manufactured by Printec); TEPIC-FL, TEPIC-PAS, TEPIC-UC (all manufactured by Nissan Chemical); etc.

Examples of alicyclic epoxy compounds include polyglycidyl ethers of polyols having at least one alicyclic structure, and compounds containing cyclohexene oxide or cyclopentene oxide obtained by epoxidizing a compound containing a cyclohexene or cyclopentene ring with an oxidizing agent. As typical compounds of these aliphatic epoxy compounds, there can be listed hydrogenated bisphenol A diglycidyl ether, 3,4-epoxyepoxyhexylmethyl-3,4-epoxyepoxyhexanecarboxylate, 3,4-epoxy-1-methylepoxyhexyl-3,4-epoxy-1-methylhexanecarboxylate, 6-methyl-3,4-epoxyepoxyhexylmethyl-6-methyl-3,4-epoxyepoxyhexanecarboxylate, 3,4-epoxy-3-methylepoxyhexylmethyl-3,4-epoxy-3-methylepoxyhexanecarboxylate. Ester, 3,4-epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), propane-2,2-diyl-bis(3,4-epoxycyclohexane), 2,2-bis(3,4-epoxycyclohexyl)propane, dicyclopentadiene diepoxide diepoxide), dicyclopentadiene dimethanol diglycidyl ether, ethylene bis(3,4-epoxycyclohexane carboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1-epoxyethyl-3,4-epoxycyclohexane, 1,2-epoxy-2-epoxyethylcyclohexane, α-pinene oxide, limonene dioxide, etc.

Furthermore, commercially available products may be used as the alicyclic epoxy compound. Examples of commercially available products include CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2000, and CELLOXIDE 3000 (all manufactured by Daicel Corporation); Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.); jER YX8000 and jER YX8034 (manufactured by Mitsubishi Chemical Corporation); ADEKA resin EP-4088S, ADEKA resin EP-4088L, and ADEKA resin EP-4080E (all manufactured by ADEKA Corporation); and the like.

Furthermore, as a compound having an ethylene oxide group in a molecule, an epoxy compound having both an alicyclic structure and an aromatic ring in one molecule can also be cited. As such a compound, for example, Epiclon HP-7200 (manufactured by DIC Corporation) can be cited.

Among them, from the viewpoint of reducing the dielectric constant of the adhesive cured layer and the viewpoint of easily forming a colorless and transparent adhesive cured layer, as the compound having an ethylene oxide group, an aliphatic epoxy resin is preferred. Furthermore, when the adhesive layer includes a cationic polymerization initiator, from the viewpoint of high reactivity of cationic polymerization to avoid the cationic polymerization proceeding too slowly, an aliphatic epoxy resin is preferred. Furthermore, when a thermal cationic polymerization initiator is used as a curing agent described later, the compound having an ethylene oxide group is preferably a compound having a glycidyl ether group. Cationic polymerization involving glycidyl ether groups tends to proceed relatively smoothly. Therefore, when there is a step of heating the composition including the components constituting the adhesive layer (for example, a step of heating to 90° C. or higher) during the production process of the adhesive layer, the polymerization reaction of the glycidyl ether group is difficult to proceed, and the adhesive layer is likely to maintain a low storage modulus at 23° C. The content of the compound having a glycidyl ether group is preferably 70% by mass or more, and more preferably 90% by mass or more, relative to the entire compound having a cyclic ether group. Furthermore, when the content of the compound having a glycidyl ether group is 90 mass % or more relative to the entire compound having a cyclic ether group, the storage stability of the adhesive layer can be improved.

Examples of compounds having an oxycarbonyl group in the molecule include 3,7-bis(3-oxocyclobutane)-5-oxo-nonane, 1,4-bis[(3-ethyl-3-oxocyclobutanemethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxocyclobutanemethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxocyclobutanemethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxocyclobutanemethyl)ether, triethylene glycol bis(3-ethyl-3-oxocyclobutanemethyl)ether, tetraethylene glycol bis(3-ethyl-3-oxocyclobutanemethyl)ether, and tetraethylene glycol bis(3-ethyl-3-oxocyclobutanemethyl)ether. difunctional aliphatic oxycarbon compounds such as alcohol bis(3-ethyl-3-oxocyclobutanylmethyl)ether, 1,4-bis(3-ethyl-3-oxocyclobutanylmethoxy)butane, 1,6-bis(3-ethyl-3-oxocyclobutanylmethoxy)hexane, and monofunctional oxycarbon compounds such as 3-ethyl-3-[(phenoxy)methyl]oxycarbon, 3-ethyl-3-(hexyloxymethyl)oxycarbon, 3-ethyl-3-(2-ethylhexyloxymethyl)oxycarbon, 3-ethyl-3-(hydroxymethyl)oxycarbon, and 3-ethyl-3-(chloromethyl)oxycarbon.

Commercially available products can also be used as compounds having an oxygen group in the molecule. Examples of commercially available products include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether (all manufactured by Maruzen Petrochemical Co., Ltd.); ARONE OXETANE OXT-121, OXT-221, EXOH, POX, OXA, OXT-101, OXT-211, and OXT-212 (all manufactured by Toagosei Co., Ltd.); Eternacoll OXBP and OXTP (all manufactured by Ube Industries, Ltd.), etc.

The above-mentioned cyclic ether compound (A) may be used alone or in combination of two or more.

The content of the cyclic ether compound (A) in the adhesive layer (the total amount when two or more cyclic ether compounds (A) are included) is preferably 53 to 80 mass %, and more preferably 57 to 75 mass % relative to the adhesive layer as a whole. By making the content of the cyclic ether compound (A) within the above range, it becomes easy to obtain an adhesive cured layer with a high storage modulus at 90°C.

At least one of the cyclic ether compounds (A) in the adhesive layer is preferably a compound that is liquid at 25°C (cyclic ether compound (AL)). Here, the so-called liquid is one of the aggregation states of the substance, which means a state with a substantially fixed volume but no specific shape. The cyclic ether compound (AL) preferably has a viscosity of 2 to 10000 mPa·s measured at 25°C and 1.0 rpm using an E-type viscometer. By using the cyclic ether compound (AL), the storage modulus of the adhesive layer at 23°C can be suppressed from becoming too high. Therefore, it becomes easy to obtain an adhesive layer having sufficient adhesion at room temperature and excellent adhesion.

From the viewpoint of adjusting the storage modulus of the adhesive layer at 23° C., the cyclic ether equivalent of the cyclic ether compound (AL) is preferably 150 to 1000 g/eq, more preferably 240 to 900 g/eq.

The content of the cyclic ether compound (AL) in the adhesive layer (the total amount when two or more compounds are included) is preferably 53% by mass or more, and more preferably 57% by mass or more relative to the entire adhesive layer. By making the content of the cyclic ether compound (AL) 53% by mass or more relative to the entire adhesive layer, it becomes easy to obtain an adhesive layer having sufficient adhesion at room temperature and excellent adhesion. It is also easy to obtain an adhesive cured material layer with a high storage modulus at 90°C.

The content of the cyclic ether compound (AL) in the adhesive layer (the total amount when two or more compounds are included) is preferably 70 mass % or less, and more preferably 68 mass % or less, relative to the adhesive layer as a whole. By making the content of the cyclic ether compound (AL) less than 70 mass % relative to the adhesive layer as a whole, it becomes easy to obtain an adhesive sheet for device sealing having excellent peeling properties of the peelable film.

(Binder resin) The adhesive layer may also include an adhesive resin (B). The adhesive layer including the adhesive resin (B) has excellent shape retention and workability.

The weight average molecular weight (Mw) of the binder resin (B) is not particularly limited, but is preferably 10,000 or more, preferably 10,000 to 150,000, and more preferably 10,000 to 100,000, because of better compatibility with the cyclic ether compound (A) and better shape retention. Gel permeation chromatography (GPC) can be performed using tetrahydrofuran (THF) as a solvent, and the value measured in terms of standard polystyrene is the weight average molecular weight (Mw) of the binder resin (B).

When the adhesive layer includes an adhesive resin (B), the content of the adhesive resin (B) relative to the entire adhesive layer (the total amount when two or more adhesive resins (B) are included) is preferably 20 to 46 mass %, and more preferably 23 to 44 mass %. When the content of the adhesive resin (B) is within the above range, it becomes easy to obtain an adhesive layer having excellent shape retention and sufficient adhesiveness.

As the adhesive resin (B), a resin having a glass transition temperature (Tg) of 60°C or higher is preferred, a resin having a glass transition temperature (Tg) of 90°C or higher is preferred, and a resin having a glass transition temperature (Tg) of 110°C or higher is further preferred. By using a resin having a glass transition temperature (Tg) of 60°C or higher, it becomes easy to set the storage modulus of the adhesive cured layer at 90°C to 1×10 ⁸ Pa or higher. Furthermore, by setting the glass transition temperature (Tg) of the adhesive resin (B) to 90°C or higher, it becomes easy to set the storage modulus of the adhesive layer at 23°C to a range of 9.5×10 ⁵ Pa or higher as described later even when a large amount of the cyclic ether compound (AL) is included. The glass transition temperature (Tg) of the binder resin (B) can be measured using a differential scanning calorimeter in accordance with JIS K7121.

As the binder resin (B), there can be listed phenoxy resins, polyimide resins, polyamide imide resins, polyvinyl butyral resins, polycarbonate resins, acrylic resins, polyurethane resins, modified olefin resins, etc. The above resins can be used alone or in combination of two or more.

The adhesive resin (B) is preferably at least one selected from the group consisting of phenoxy resins and modified olefin resins, and preferably a phenoxy resin from the viewpoint of increasing the storage modulus of the adhesive cured layer at 90°C.

Phenoxy resins generally correspond to high molecular weight epoxy resins and refer to resins having a degree of polymerization of about 100 or more.

The weight average molecular weight (Mw) of the phenoxy resin is preferably 10,000 to 150,000, and more preferably 10,000 to 100,000. The value measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent is the weight average molecular weight (Mw) of the phenoxy resin in terms of standard polystyrene. Phenoxy resins, which correspond to such high molecular weight epoxy resins, have excellent heat deformation resistance. The epoxy equivalent of the phenoxy resin is preferably 5,000 or more, and more preferably 7,000 or more. The epoxy equivalent value of the phenoxy resin can be measured in accordance with JIS K7236.

Examples of phenoxy resins include bisphenol A type, bisphenol F type, bisphenol S type phenoxy resins, copolymer type phenoxy resins of bisphenol A type and bisphenol F type, distillates thereof, naphthalene type phenoxy resins, novolac type phenoxy resins, biphenyl type phenoxy resins, cyclopentadiene type phenoxy resins, and the like. These phenoxy resins may be used alone or in combination of two or more.

Phenoxy resins can be obtained by reacting difunctional phenols with epihalohydrin to a high molecular weight, or by addition polymerization of difunctional epoxy resins with difunctional phenols. For example, difunctional phenols can be reacted with epihalohydrin in an inert solvent at a temperature of 40 to 120°C in the presence of an alkali metal hydroxide. Furthermore, it can also be obtained by heating a difunctional epoxy resin and a difunctional phenol to 50 to 200° C. at a reaction solid component concentration of 50% by weight or less in an organic solvent having a boiling point of 120° C. or above, such as an amide solvent, ether solvent, ketone solvent, lactone solvent, alcohol solvent, etc., in the presence of a catalyst such as an alkali metal compound, an organic phosphorus compound, or a cyclic amine compound, to carry out an addition polymerization reaction.

The difunctional phenols are not particularly limited as long as they are compounds having two phenolic hydroxyl groups. Examples thereof include monocyclic difunctional phenols such as hydroquinone, 2-bromohydroquinone, resorcinol, o-catechol, bisphenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, dihydroxybiphenyls such as 4,4'-dihydroxybiphenyl, dihydroxyphenyl ethers such as bis(4-hydroxyphenyl)ether, and compounds having two phenolic hydroxyl groups on the aromatic ring of the above-mentioned phenol skeletons. Compounds having a linear alkyl group, a branched alkyl group, an aromatic group, a hydroxymethyl group, an allyl group, a cyclic aliphatic group, a halogen (tetrabromobisphenol A, etc.), a nitro group, etc. introduced therein; polycyclic bifunctional phenols having a linear alkyl group, a branched alkyl group, an allyl group, an allyl group having a substituent, a cyclic aliphatic group, an alkoxycarbonyl group, etc. introduced into the central carbon atom of the above-mentioned bisphenol skeleton; etc.

As epihalogen alcohols, epichlorohydrin, epibromohydrin, epiiodohydrin and the like can be listed.

Furthermore, in the present invention, commercially available products can also be used as phenoxy resins. For example, the product names of Mitsubishi Chemical Corporation include: YX7200 (glass transition temperature: 150°C), YX6954 (phenoxy resin containing bisphenol acetophenone skeleton, glass transition temperature: 130°C), YL7553, YL6794, YL7213, YL7290, YL7482, YX8100 (phenoxy resin containing bisphenol S skeleton), the product names of Tohto Chemical Co., Ltd. include: FX280, FX293, FX293S (phenoxy resin containing fluorene skeleton), and the product names of Mitsubishi Chemical Corporation include: Products manufactured by JER: jER1256, jER4250 (glass transition temperature: less than 85°C), jER4275 (glass transition temperature: 75°C), products manufactured by Nippon Steel Chemical Materials: YP-50 (glass transition temperature: 84°C), YP-50S (both are phenoxy resins containing bisphenol A skeleton), YP-70 (bisphenol A skeleton/bisphenol F skeleton copolymer phenoxy resin, glass transition temperature: less than 85°C), ZX-1356-2 (glass transition temperature: 72°C), etc. In addition, for materials with known glass transition temperatures, the glass transition temperature is listed.

The modified olefin resin is an olefin resin into which a functional group is introduced by subjecting an olefin resin as a precursor to modification treatment using a modifying agent.

The so-called olefinic resin refers to a polymer including repeating units derived from olefinic monomers. The olefinic resin may be a polymer consisting of repeating units derived only from olefinic monomers, or a polymer consisting of repeating units derived from olefinic monomers and monomers copolymerizable with olefinic monomers.

As the olefin monomer, α-olefins having 2 to 8 carbon atoms are preferred, ethylene, propylene, 1-butene, isobutylene, or 1-hexene are preferred, and ethylene or propylene is more preferred. The above-mentioned olefin monomers can be used alone or in combination of two or more. As monomers copolymerizable with the olefin monomers, vinyl acetate, (meth)acrylate, styrene, etc. can be listed. Here, "(meth)acrylic acid" means acrylic acid or methacrylic acid (hereinafter the same). The above-mentioned monomers copolymerizable with the olefin monomers can be used alone or in combination of two or more.

Examples of olefin resins include very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), ethylene-propylene copolymer, olefin elastomer (TPO), ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylate copolymer.

The modifier used for the modification treatment of olefin resins is a compound having a functional group in the molecule. As the functional group, there can be listed carboxyl group, carboxylic anhydride group, carboxylic ester group, hydroxyl group, epoxy group, amide group, ammonium group, nitrile group, amino group, imide group, isocyanate group, acetyl group, thiol group, ether group, sulfide group, sulfonate group, phosphine group, nitro group, urethane group, alkoxysilyl group, silanol group, halogen atom, etc. The compound having a functional group may have two or more functional groups in the molecule.

The weight average molecular weight (Mw) of the modified olefin resin is preferably 10,000 to 150,000, and more preferably 30,000 to 100,000. Gel permeation chromatography (GPC) can be performed using tetrahydrofuran (THF) as a solvent, and the value measured in terms of standard polystyrene is the weight average molecular weight (Mw) of the modified olefin resin.

As the modified olefin resin, an acid-modified olefin resin is preferred. The acid-modified olefin resin refers to a resin obtained by graft-modifying an olefin resin with an acid or an acid anhydride. For example, a resin obtained by reacting an olefin resin with an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride (hereinafter sometimes referred to as "unsaturated carboxylic acid, etc.") to introduce a carboxyl group or a carboxylic acid anhydride group (graft modification) can be cited.

As unsaturated carboxylic acids that react with olefin resins, there can be listed unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, liconic acid, glutaconic acid, tetrahydrophthalic acid, and uronic acid; unsaturated carboxylic anhydrides such as maleic anhydride, itaconic anhydride, glutaconic anhydride, liconic anhydride, uronic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride; etc. The above can be used alone or in combination of two or more. Among them, maleic anhydride is preferred because it is easy to obtain a sealing material with higher adhesion strength.

The content of the unsaturated carboxylic acid or the like that can react with the olefinic resin is preferably 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass, and more preferably 0.2 to 1 part by mass relative to 100 parts by mass of the olefinic resin. The adhesive layer including the acid-modified olefinic resin obtained thereby hardens and can form a sealing material with higher adhesive strength.

The method of introducing the unsaturated carboxylic acid unit or the unsaturated carboxylic acid anhydride unit into the olefinic resin is not particularly limited. For example, there can be cited a method of heating the olefinic resin and the unsaturated carboxylic acid to a temperature above the melting point of the olefinic resin in the presence of a free radical generator such as an organic peroxide or nitrogen nitrile to melt and react, or a method of dissolving the olefinic resin and the unsaturated carboxylic acid in an organic solvent and then heating and stirring in the presence of a free radical generator to react, etc., to graft copolymerize the olefinic resin with the unsaturated carboxylic acid.

Commercially available products may also be used as the acid-modified olefinic resin. Examples of commercially available products include Admer (registered trademark) (manufactured by Mitsui Chemicals, Inc.), Unistole (registered trademark) (manufactured by Mitsui Chemicals, Inc.), BondyRam (manufactured by Polyram, Inc.), Orevac (registered trademark) (manufactured by ARKEMA, Inc.), and Modic (registered trademark) (manufactured by Mitsubishi Chemical Corporation).

[Hardener] The adhesive layer may also include a hardener. When the adhesive layer includes a hardener, the curability of the adhesive layer can be further improved. The hardener is not particularly limited as long as it can induce a curing reaction, but from the perspective that the step of curing the adhesive layer using energy rays such as ultraviolet rays may be difficult or should be avoided, or from the perspective that it is not necessary to introduce an energy ray irradiation device, it is preferable to use a hardener that can induce a curing reaction by heating. As hardeners, thermal cationic polymerization initiators and other hardeners can be listed. As the hardener other than the thermal cationic polymerization initiator, there can be listed tertiary amines such as benzylmethylamine and 2,4,6-tris-dimethylaminomethylphenol; imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-heptadecylimidazole; Lewis acids such as boron trifluoride/monoethylamine complex and boron trifluoride/piperazine complex; and the like.

The hardener may be used alone or in combination of two or more. When the adhesive layer includes a hardener, the content of the hardener is not particularly limited, but is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the cyclic ether compound (A).

The adhesive layer preferably includes at least one thermal cationic polymerization initiator as a curing agent. By using a thermal cationic polymerization initiator, the curability of the adhesive layer can be precisely controlled.

Thermal cationic polymerization initiators are compounds that can generate cationic species that initiate polymerization by heating. As thermal cationic polymerization initiators, sulfonium salts, quaternary ammonium salts, phosphonium salts, diazonium salts, iodonium salts, etc. can be listed.

Examples of the coronium salt include triphenyl tetrafluoroborate, triphenyl hexafluoroarsonate, triphenylsulphonium hexafluoroarsenate, tris(4-methoxyphenyl) hexafluoroarsenate, diphenyl(4-phenylthiophenyl) hexafluoroarsenate, (4-acetyloxyphenyl)methyl(2-methylbenzyl)tetrakis(pentafluorophenyl)borate, (4-hydroxyphenyl)methyl(4-methylbenzyl)tetrakis(pentafluorophenyl)borate, (4-acetyloxyphenyl)benzyl(methyl)tetrakis(pentafluorophenyl)borate, and benzyl(4-hydroxyphenyl)(methyl)tetrakis(pentafluorophenyl)borate.

Commercially available products can also be used as cobalt salts. As commercially available products, there are Adeka Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, Adeka Opton CP-77 (all manufactured by Asahi Denka Corporation), Sunaid SI-60L, Sunaid SI-80L, Sunaid SI-100L, Sunaid SI-B2A, Sunaid SI-B7, Sunaid SI-B3A, Sunaid SI-B3 (all manufactured by Sanshin Chemical Corporation), CYRACURE UVI-6974, CYRACURE UVI-6990 (manufactured by Union Carbide Corporation), UVI-508, UVI-509 (manufactured by General Electric Corporation), FC-508, FC-509 (manufactured by Minnesota Mining and Manufacturing Corporation), and FC-509, FC-508, FC-509 (manufactured by Minnesota Mining and Manufacturing Corporation). Manufacturing, 3M), CD-1010, CD-1011 (all manufactured by Sartomer), CI series products (all manufactured by Nippon Soda Co., Ltd.), etc.

As quaternary ammonium salts, there are tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogen sulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, and tetrabutylammonium hexafluoroborate. hexafluoroantimonate), N,N-diethyl-N-benzyl trifluoromethanesulfonate, N,N-dimethyl-N-(4-methoxybenzyl) pyridinium hexafluoroantimonate, N,N-diethyl-N-(4-methoxybenzyl) toluidinium hexafluoroantimonate, etc.

As the phosphonium salt, ethyltriphenylphosphonium hexafluoroantibonate, tetrabutylphosphonium hexafluoroantibonate, and the like can be cited.

Examples of diazonium salts include AMERICURE (manufactured by American Can Co., Ltd.) and ULTRASET (manufactured by Asahi Denka Co., Ltd.).

Examples of the iodonium salt include diphenyliodonium hexafluoroarsenate, bis(4-chlorophenyl)iodonium hexafluoroarsenate, bis(4-bromophenyl)iodonium hexafluoroarsenate, and phenyl(4-methoxyphenyl)iodonium hexafluoroarsenate. In addition, as commercially available products, UV-9310C (manufactured by Toshiba Organic Silicon Co., Ltd.), Photoinitiator 2074 (manufactured by Rhone-Poulenc), UVE series products (manufactured by General Electric Co., Ltd.), and FC series products (manufactured by Minnesota Mining and Manufacturing (3M) Co., Ltd.) can also be used.

The thermal cationic polymerization initiator may be used alone or in combination of two or more.

In the device sealing adhesive sheet of the present invention, it is preferred that all the hardeners contained in the adhesive layer are thermal cationic polymerization initiators. If a hardener other than a thermal cationic polymerization initiator is used, there is a concern that the adhesive layer may be colored or the transparency of the adhesive layer may be reduced. On the other hand, when a thermal cationic polymerization initiator is used, the above-mentioned problem is less likely to occur. Therefore, by making all the hardeners contained in the adhesive layer be thermal cationic polymerization initiators, a colorless and transparent adhesive layer can be efficiently formed.

(Silane coupling agent) The adhesive layer may also include a silane coupling agent. By hardening the adhesive layer including the silane coupling agent, a sealing material having better wet and heat durability can be formed.

As the silane coupling agent, a known silane coupling agent can be used, and among them, an organic silicon compound having at least one alkoxysilyl group in the molecule is preferred.

As silane coupling agents, there can be listed silane coupling agents having (meth)acryloyl groups, such as 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltrimethoxysilane, vinyltriethoxy ...ethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, Silane coupling agents with vinyl groups such as 2-(3,4-epoxyhexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, etc.; Silane coupling agents with styryl groups such as p-styryltrimethoxysilane and p-styryltriethoxysilane;

N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene)propylamine Silane coupling agents with amino groups, such as N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, and N-(2-aminoethyl)-8-aminooctyltrimethoxysilane; Silane coupling agents with urea groups, such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane. reido) silane coupling agent; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and other silane coupling agents with halogen atoms; 3-butylpropylmethyldimethoxysilane, 3-butylpropyltrimethoxysilane and other silane coupling agents with butyl groups; bis(triethoxysilylpropyl) tetrasulfide (bis(triethoxysilylpropyl) tetrasulfide), bis(triethoxysilylpropyl) tetrasulfide and other silane coupling agents with sulfide groups; 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane and other silane coupling agents with isocyanate groups; Allyl trichlorosilane, allyl triethoxysilane, allyl trimethoxysilane and other silane coupling agents with allyl groups; 3-hydroxypropyl trimethoxysilane, 3-hydroxypropyl triethoxysilane and other silane coupling agents with hydroxyl groups; etc. Among them, from the viewpoint of improving the adhesion of the adhesive layer to the adherend, it is preferred to use a long-chain spacer type silane coupling agent having a linear alkyl group with 6 or more carbon atoms. As long-chain spacer type silane coupling agents having a linear alkyl group with 6 or more carbon atoms, 8-methacryloyloxyoctyl trimethoxysilane, 7-octenyl trimethoxysilane, 8-glycidoxyoctyl trimethoxysilane, N-(2-aminoethyl)-8-aminooctyl trimethoxysilane, etc. can be listed, and 8-glycidoxyoctyl trimethoxysilane is preferred. The above-mentioned silane coupling agents can be used alone or in combination of two or more.

When the adhesive layer includes a silane coupling agent, the content of the silane coupling agent is preferably 0.01 to 5 mass %, and more preferably 0.05 to 1 mass %, relative to the entire adhesive layer.

[Other components] The adhesive layer may include other components within the scope that does not hinder the effect of the present invention. As other components, additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders, softeners, and thickeners can be listed. The above components can be used alone or in combination of two or more. When the adhesive layer includes the above additives, the content can be appropriately determined according to the purpose.

(Adhesive layer) The shape and size of the adhesive layer are not particularly limited. The adhesive layer may be rectangular or strip-shaped. In this specification, the so-called "strip-shaped" refers to a shape in which the length is more than 5 times the width, and preferably more than 10 times the width. Specifically, it means a shape of a film having a length sufficient to be rolled up for storage or transportation. The upper limit of the ratio of the length to the width of the film is not particularly limited, and may be, for example, less than 100,000 times.

The thickness of the adhesive layer is generally 1 to 50 μm, preferably 1 to 25 μm, and more preferably 5 to 25 μm. An adhesive layer having a thickness within the above range is suitable for use as a material for forming a sealant. The thickness of the adhesive layer can be measured using a known thickness gauge in accordance with JIS K 7130 (1999).

The adhesive layer may have a single-layer structure or a multi-layer structure (composed of a plurality of adhesive layers stacked on top of each other). The adhesive layer may have a uniform component or a non-uniform component (for example, in an adhesive layer having the above-mentioned multi-layer structure, two components are mixed at the interface between two adhesive layers, forming a single-layer structure in appearance).

The storage modulus of the adhesive layer at 23°C is 9.5×10 ⁵ Pa to 3.0×10 ⁷ Pa, preferably 9.9×10 ⁵ Pa to 2.0×10 ⁷ Pa. Furthermore, since the pressure when the adhesive layer is attached to the sealed object can be reduced, the storage modulus of the adhesive layer at 23°C is preferably 1.3×10 ⁷ Pa or less, preferably 1.1×10 ⁷ Pa or less, and even more preferably 1.0×10 ⁷ Pa or less.

By setting the storage modulus of the adhesive layer at 23°C to 9.5×10 ⁵ Pa or more, when the device sealing adhesive sheet is cut into a predetermined shape, the punching knife can be cut into the device sealing adhesive sheet without causing significant deformation of the adhesive layer. Therefore, it is possible to avoid the adhesive from adhering to the unpeeled portion of the end of the peeling film, and the peeling film can be peeled efficiently. For example, by using a compound with a large cyclic ether equivalent as the cyclic ether compound (A), it becomes easy to obtain an adhesive layer having a storage modulus of 9.5×10 ⁵ Pa or more at 23°C. Furthermore, by reducing the content of the cyclic ether compound (AL) in the adhesive layer, the storage modulus of the adhesive layer at 23°C can be reduced. Furthermore, by using a relatively rigid resin such as a phenoxy resin, an adhesive layer having a storage modulus of 9.5×10 ⁵ Pa or more at 23°C can be easily obtained even when the content of the cyclic ether compound (AL) in the adhesive layer is high.

By setting the storage modulus of the adhesive layer at 23°C to 3.0×10 ⁷ Pa or less, the adhesive layer has sufficient adhesive force at room temperature and has excellent adhesion. For example, by increasing the amount of the cyclic ether compound (AL), it is easy to obtain an adhesive layer having a storage modulus of 3.0×10 ⁷ Pa or less at 23°C. Furthermore, as described above, when the adhesive layer includes a thermal cationic polymerization initiator, the cyclic ether compound (A) is a compound having a glycidyl ether group, which can reduce the storage modulus of the adhesive layer at 23°C and make it easy to set it to 3.0×10 ⁷ Pa or less. The storage modulus of the adhesive layer can be measured using a known dynamic viscoelasticity measuring device. Specifically, it can be measured according to the method described in the embodiment.

The adhesive layer has curing properties. That is, by subjecting the adhesive layer to a predetermined curing treatment, the cyclic ether group in the cyclic ether compound (A) reacts, and the adhesive layer is cured to form an adhesive cured material layer. As the curing treatment, heat treatment or light treatment can be listed. It can be appropriately determined according to the properties of the adhesive layer.

The storage modulus of the adhesive cured layer at 90°C is preferably 1×10 ⁸ Pa or more, and more preferably 1×10 ⁹ to 1×10 ¹¹ Pa. The adhesive cured layer having a storage modulus of 1×10 ⁸ Pa or more at 90°C has excellent sealing properties and is therefore more suitable as a sealing material. Furthermore, after the adhesive cured layer is formed, it becomes easier to prevent the adhesive cured layer from cracking or peeling during the manufacturing process of the device seal. The storage modulus of the adhesive cured layer can be measured using a known dynamic viscoelasticity measuring device. Specifically, it can be measured according to the method described in the embodiment.

The adhesive cured layer has excellent adhesive strength. When the 180° peel test is performed at a temperature of 23°C and a relative humidity of 50%, the adhesive strength of the adhesive cured layer is generally 1 to 20 N/25 mm, preferably 2.5 to 15 N/25 mm. For example, the 180° peel test can be performed at a temperature of 23°C and a relative humidity of 50% according to the adhesive force measurement method described in JIS Z0237:2009.

When the device sealing adhesive sheet of the present invention is used to form a sealing material in an optical device such as a light-emitting device, a light-receiving device, a display device, etc., the adhesive cured layer preferably has excellent colorless transparency. The total light transmittance of the adhesive cured layer with a thickness of 15 μm is preferably 85% or more, and more preferably 90% or more. There is no specific upper limit for the total light transmittance, but it is usually 99% or less. The total light transmittance can be measured according to JIS K7361-1:1997.

The water vapor permeability of the adhesive cured layer is usually 0.1 to 200 g·m ^-2 ·day ^-1 , preferably 1 to 150 g·m ^-2 ·day ^-1 . The water vapor permeability can be measured using a known gas permeability measuring device.

[Peel film] The device sealing adhesive sheet of the present invention includes a first peel film and a second peel film. When the device sealing adhesive sheet is used, the peel film is usually peeled off and removed. At this time, the second peel film is peeled off and removed before the first peel film. Since the second peel film can be peeled off and removed efficiently, it is preferable that the peeling force of the second peel film is lower than the peeling force of the first peel film. In the following description, the "first peel film" and the "second peel film" are sometimes not distinguished and are simply referred to as the "peel film".

The peeling film serves as a support during the manufacturing process of the device sealing adhesive sheet and as a protective sheet for the adhesive layer before the device sealing adhesive sheet is used.

As the release film, a conventionally known release film can be used. For example, a release film having a release layer on a release film substrate can be cited. The release layer can be formed using a known release agent.

As the base material for the release film, there can be listed paper base materials such as glassine, coated paper, and woodfree paper; laminated paper with thermoplastic resins such as polyethylene laminated on the above paper base material; plastic films such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polypropylene resin, polyethylene resin, etc.; etc. As the release agent, there can be listed rubber elastomers such as silicone resins, olefin resins, isoprene resins, butadiene resins, long chain alkane resins, alkyd resins, fluorine resins, etc. There is no particular limit to the thickness of the peeling film, but it is usually about 20 to 250 μm.

[Device Sealing Adhesive Sheet] The device sealing adhesive sheet of the present invention includes the aforementioned first peeling film and second peeling film, and the aforementioned adhesive layer sandwiched between these peeling films As the device sealing adhesive sheet of the present invention, a three-layer structure of first peeling film/adhesive layer/second peeling film can be listed.

The manufacturing method of the device sealing adhesive sheet of the present invention is not particularly limited. For example, the device sealing adhesive sheet can be manufactured using a casting method.

When manufacturing an adhesive sheet for device sealing by casting, it can be manufactured, for example, by the following method. Two peeling films (peeling film (A) and peeling film (B)) having peeling layers and a coating liquid including components constituting an adhesive layer are prepared. The coating liquid is applied to the peeling layer surface of the peeling film (A) by a known method, and the obtained coating film is dried to form an adhesive layer. Next, the release film (B) can be placed on the adhesive layer so that the release layer surface of the release film (B) contacts the adhesive release layer, thereby obtaining an adhesive sheet for device sealing.

When the components constituting the adhesive layer are diluted to prepare a coating liquid, examples of solvents used to prepare the coating liquid include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and n-heptane; aliphatic cyclopentane, cyclohexane, and methylcyclohexane; and the like. The above solvents may be used alone or in combination of two or more. The content of the solvent may be appropriately determined in consideration of coating properties and the like.

As a coating method of the coating liquid, there can be listed a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, and the like.

As methods for drying the solvent in the coating, hot air drying, hot roller drying, infrared irradiation, and conventionally known drying methods can be cited. As conditions for drying the coating, for example, 30 seconds to 5 minutes at 80 to 150°C, and 1 minute to 4 minutes at 90 to 120°C are preferred. By drying the coating at 90°C or above, the coating can be easily dried even if the drying time is less than 5 minutes, and the productivity is excellent.

The method for manufacturing a sealed body using the device sealing adhesive sheet of the present invention is not particularly limited. For example, the device sealed body can be manufactured by sealing the sealed object (device) by performing the following steps (a1) to (a5) or steps (b1) to (b5).

Step (a1): The second peeling film of the device sealing adhesive sheet is peeled off and removed to obtain a device sealing intermediate. Step (a2): The adhesive layer exposed by performing step (a1) is attached to the sealed object (device). Step (a3): The first peeling film is further peeled off and removed from the device sealing intermediate. Step (a4): The adhesive layer exposed by performing step (a3) is attached to a substrate (glass plate, gas barrier film, etc.). Step (a5): The adhesive layer is cured by a predetermined method to form an adhesive cured material layer.

Step (b1): peel off and remove the second peeling film of the device sealing adhesive sheet to obtain the device sealing intermediate. Step (b2): attach the adhesive layer exposed by step (b1) to a substrate (glass plate, gas barrier film, etc.). Step (b3): further peel off and remove the first peeling film from the device sealing intermediate. Step (b4): attach the adhesive layer exposed by step (b3) to the sealed object (device). Step (b5): harden the adhesive layer in a predetermined manner to form an adhesive hardened layer.

In the above-mentioned method for manufacturing a device seal, from the viewpoint of simplicity of operation and productivity, the step of attaching the adhesive layer to the sealed object or substrate in step (a2) or step (b2) is preferably carried out at room temperature (15 to 35° C., the same applies hereinafter). Similarly, step (b4) is also preferably carried out at room temperature.

The device sealing adhesive sheet of the present invention can be cut into the device sealing adhesive sheet with a punching knife without causing significant deformation of the adhesive layer when it is cut into a predetermined shape. Therefore, it is possible to avoid the adhesive from adhering to the unpeeled portion of the end of the peeling film, and the peeling film can be peeled off efficiently. Moreover, the adhesive cured layer formed using the adhesive layer constituting the device sealing adhesive sheet of the present invention has excellent adhesive strength and water vapor barrier properties. Therefore, the device sealing adhesive sheet of the present invention is suitable for use as a forming material of a sealing material in a device sealing body.

The device seal is not particularly limited. As the device seal, optical devices such as light-emitting devices, light-receiving devices, and display devices can be listed. In the case where the adhesive layer has high light transmittance, the device seal adhesive sheet of the present invention is preferably used as a forming material of a sealant in an optical device seal. As specific examples thereof, organic EL devices such as organic EL displays and organic EL lighting; liquid crystal displays; electronic paper; solar cells such as inorganic solar cells and organic thin film solar cells; and the like can be listed.

When the adhesive cured layer obtained by the adhesive layer constituting the device sealing adhesive sheet of the present invention is transparent, the device sealing adhesive sheet of the present invention is suitable for use as a material for forming a sealant in devices such as organic EL displays, organic EL lighting, liquid crystal displays, electronic paper, etc. [Example]

The following examples are given to illustrate the present invention in more detail. However, the present invention is not limited to the following examples.

[Compounds used in Examples or Comparative Examples] ・Cyclic ether compound (AL1): Hydrogenated bisphenol A type glycidyl ether epoxy resin [manufactured by Mitsubishi Chemical Corporation, trade name: YX8000, liquid at 25°C, epoxide equivalent: 205 g/eq] ・Cyclic ether compound (AL2): Hydrogenated bisphenol A type glycidyl ether epoxy resin [manufactured by Mitsubishi Chemical Corporation, trade name: YX8034, Liquid at 25°C, epoxy equivalent: 270g/eq] ・Binder resin (B1): (phenoxy resin, manufactured by Mitsubishi Chemical, trade name: YX7200B35, glass transition temperature (Tg): 150°C) ・Hardener (C1): Thermal cationic polymerization initiator: benzyl (4-hydroxyphenyl) (methyl) tetrakis (pentafluorophenyl) borate (manufactured by Sanshin Chemical, trade name: Sunaid SI-B3) ・Hardener (C2): Imidazole hardener (manufactured by Shikoku Chemical Industries, Ltd., trade name: Curezol 2E4MZ) ・Silane coupling agent (D1): 8-glycidoxyoctyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industries, Ltd., trade name: KBM4803) ・Peeling film (E1): Manufactured by Lintec Co., Ltd., trade name: SP-PET752150 ・Peeling film (E2): Manufactured by Lintec Co., Ltd., trade name: SP-PET381130

[Example 1] 130 parts by mass of a cyclic ether compound (AL1), 100 parts by mass of an adhesive resin (B1), 3.8 parts by mass of a hardener (C1), and 0.2 parts by mass of a silane coupling agent (D1) were dissolved in methyl ethyl ketone to prepare a coating liquid. The coating liquid was applied to the peeling-treated surface of a release film (E1) (first release film), and the obtained coating film was dried at 100°C for 2 minutes to obtain an adhesive layer with a thickness of 15 μm. The peeling-treated surface of the peeling film (E2) (second peeling film) is bonded onto the adhesive layer to obtain an adhesive sheet for device sealing.

[Example 2, Comparative Examples 1 and 2] Except that the types and amounts of the components constituting the adhesive layer were changed to those listed in Table 1, the adhesive sheet for device sealing was obtained in the same manner as in Example 1.

The following tests were performed on the device sealing adhesive sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2. The results are shown in Table 1.

(1) Storage modulus of adhesive layer The adhesive layer of the device sealing adhesive sheet obtained in the embodiment or the comparative example was laminated to a thickness of about 1 mm at 23°C using a laminator, and the obtained laminate was used as a measurement sample to measure its storage modulus. That is, for this measurement sample, a storage modulus measuring device (manufactured by Anton Paar, trade name: Physica MCR301) was used to measure the storage modulus in the temperature range of -20 to +150°C under the conditions of a frequency of 1 Hz, a strain of 1%, and a heating rate of 3°C/min. The measurement results at 23°C are shown in Table 1.

(2) Storage modulus of cured adhesive layer The adhesive layer of the device sealing adhesive sheet obtained in the embodiment or the comparative example was laminated to a thickness of 200 μm at 23°C using a laminating press, and the obtained laminate was heated at 110°C for 1 hour to obtain a cured product. This cured product was used as a measurement sample to measure its storage modulus. That is, for this measurement sample, a storage modulus measuring device (manufactured by TA Instrument, trade name: DMAQ800) was used to measure the storage modulus in the temperature range of -20 to +150°C under the conditions of a frequency of 11 Hz, an amplitude of 5 μm, and a heating rate of 3°C/min. The measurement results at 90°C are shown in Table 1.

(3) Evaluation of the adhesion adaptability of the adhesive layer to the sealed object The device sealing adhesive sheet obtained in the embodiment and the comparative example was cut to obtain a test piece with a width of 50 mm and a length of 150 mm. The adhesive layer exposed by peeling off the second peeling film of the obtained test piece was placed on an alkali-free glass plate at a temperature of 23°C and a relative humidity of 50%, and a pressure of 0.5 MPa was further applied using a pressure roller. The state of the adhesive layer floating from the alkali-free glass plate was observed, and the one without floating was evaluated as A, and the one with floating was evaluated as B.

(4) Evaluation of cutting processability of device sealing adhesive sheet The device sealing adhesive sheet obtained in the embodiment and comparative example was cut into a size of 150 mm in length and 165 mm in width using an air-type sample cutting device. Specifically, a punching knife of the above size was inserted from the side of the second peeling film of the device sealing adhesive sheet to cut the device sealing adhesive sheet, thereby obtaining a test sheet. The second peeling film of the obtained test sheet was peeled off and removed. At this time, the adhesive layer was not peeled off from the first peeling film, and the adhesive layer was attached to the end of the second peeling film and the adhesive layer was peeled off from the first peeling film. The evaluation was A, and the adhesive layer was attached to the end of the second peeling film and the adhesive layer was peeled off from the first peeling film. The evaluation was B.

[Table 1]

The following can be learned from Table 1. The adhesive layer of the device sealing adhesive sheet obtained in Examples 1 and 2 has excellent adhesion at 23°C. Moreover, these device sealing adhesive sheets also have excellent cutting processability, and can efficiently peel off the peeling film. On the other hand, although the adhesive layer of the device sealing adhesive sheet obtained in Comparative Example 1 has excellent adhesion at 23°C, the storage modulus of the adhesive layer at 23°C is too low, and the cutting processability of this device sealing adhesive sheet is poor. Furthermore, the adhesive layer of the device sealing adhesive sheet obtained in Comparative Example 2 has too high a storage modulus at 23°C and poor adhesion.

without.

without.

without.

Claims (8)

An adhesive sheet for device sealing, comprising a first peeling film and a second peeling film, and an adhesive layer sandwiched between the first peeling film and the second peeling film, wherein the adhesive layer satisfies the following conditions (I), (II), (III) and (IV), wherein the adhesive layer comprises one or more compounds having a cyclic ether group which are liquid at 25°C, and the adhesive layer has a storage modulus of 9.5×10 ⁵ Pa or more and 3.0×10 ⁷ Pa or less at 23°C. Pa or less, condition (III): the adhesive layer is a layer containing 53 mass % or more of a compound having a cyclic ether group which is liquid at 25°C relative to the entire adhesive layer, and condition (IV): the adhesive layer is a layer containing an adhesive resin having a glass transition temperature (Tg) of 90°C or more. The adhesive sheet for device sealing as described in claim 1, wherein the content of the compound having a cyclic ether group which is liquid at 25°C is less than 65% by mass relative to the entire adhesive layer. The device sealing adhesive sheet as described in claim 1, wherein the adhesive layer further includes a hardener, and at least one of the hardeners is a thermal cationic polymerization initiator. The device sealing adhesive sheet as described in claim 3, wherein all of the aforementioned curing agents are thermal cationic polymerization initiators. The device sealing adhesive sheet as described in claim 3, wherein at least one of the aforementioned compounds having a cyclic ether group is a compound having a glycidyl ether group. The device sealing adhesive sheet as described in claim 3, wherein at least one of the aforementioned compounds having a cyclic ether group is an aliphatic epoxy resin. The adhesive sheet for device sealing as claimed in claim 1, wherein the layer obtained by curing the adhesive layer has a storage modulus of 1×10 ⁸ Pa or more at 90°C. The device sealing adhesive sheet as described in claim 1 is used to form a sealing material in an optical-related device.