TWI849085B - Sheet adhesive, sealing sheet, sealed body for electronic device, and method for manufacturing sealed body for electronic device - Google Patents

Abstract

The present invention is a sheet adhesive containing the following (A) components, (B) components, and (C) components, a sealing sheet containing the above sheet adhesive, and a sealed body formed by sealing the sealed object with the above sealing sheet. The sheet adhesive of the present invention is suitable for use as a material for forming a hardened product with excellent shape retention under high temperature conditions. (A) component: phenoxy resin with a glass transition temperature (Tg) of 110°C or more (B) component: multifunctional epoxy resin (C) component: photocatalytic ion polymerization initiator

Description

Sheet adhesive, sealing sheet, sealed body for electronic device, and method for manufacturing sealed body for electronic device

The present invention relates to a sheet adhesive suitable for use as a material for forming a cured product having excellent shape retention under high temperature conditions, a sealing sheet having the sheet adhesive, a sealed body for an electronic device in which an electronic device is sealed with the cured product of the sheet adhesive, and a method for manufacturing the sealed body for an electronic device.

In recent years, organic EL elements have attracted attention as light-emitting elements that can emit light with high brightness by low-voltage direct current drive. However, organic EL elements have a problem that the light-emitting characteristics such as light-emitting brightness, light-emitting efficiency, and light-emitting uniformity are easily deteriorated over time. This problem of deterioration of light-emitting characteristics is presumed to be caused by the infiltration of oxygen or water into the interior of the organic EL element, which deteriorates the electrode or organic layer. Therefore, the organic EL element can be sealed with a sealing material to prevent the infiltration of oxygen or water.

For example, Patent Document 1 describes a sealing material for a sheet-shaped display element including an epoxy resin having a weight average molecular weight of 100 to 500, an epoxy resin having a weight average molecular weight of 800 to 10,000, an epoxy resin having a weight average molecular weight of 20,000 to 100,000, a specific photo-cationic polymerization initiator, and a photosensitive agent. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2018-159026

[Identify the problem you want to solve]

As described in Patent Document 1, a sheet adhesive containing epoxy resin is suitable for use as a material for forming a sealing material. However, according to the review of the inventors, it is found that the cured product of the sheet adhesive containing epoxy resin will deform under high temperature conditions, and the sealing performance may be greatly reduced.

The present invention was made in view of the above-mentioned actual situation, and aims to provide a sheet adhesive suitable for use as a material for forming a cured product with excellent shape retention under high temperature conditions, a sealing sheet having the sheet adhesive, a sealed body of an electronic device formed by sealing an electronic device with the cured product of the sheet adhesive, and a method for manufacturing a sealed body of an electronic device. [Means for Solving the Problem]

To solve the above problems, the inventors of the present invention carefully examined sheet adhesives containing epoxy resins. As a result, they found that using phenoxy resins with a high glass transition temperature (Tg) as adhesive resins can obtain a cured product with excellent shape retention under high temperature conditions, and thus completed the present invention.

Therefore, according to the present invention, the following sheet adhesives [1] to [5], sealing sheets [6], sealed bodies for electronic devices [7] and [8], and methods for manufacturing sealed bodies for electronic devices [9] and [10] are provided.

[1] A sheet adhesive comprising the following (A) component, (B) component, and (C) component. (A) component: phenoxy resin having a glass transition temperature (Tg) of 110°C or higher (B) component: multifunctional epoxy resin (C) component: photocatalytic ion polymerization initiator [2] The sheet adhesive as described in [1], wherein at least one of the above (B) components is the following (BL) component, and the content of the (BL) component is 50% by mass or more relative to the total sheet adhesive. (BL) component: multifunctional epoxy resin that is liquid at 25°C [3] The sheet adhesive as described in [1] or [2], further comprising the following (D) component. (D) Component: Silane coupling agent having a long-chain spacer group [4] A sheet adhesive as described in any one of [1] to [3], which has a storage elastic modulus of 500 MPa or more at 80°C after curing. [5] A sheet adhesive as described in any one of [1] to [4], which is used for sealing electronic devices. [6] A sealing sheet having an adhesive layer formed by the sheet adhesive as described in any one of [1] to [5], and a functional film. [7] A sealed body for an electronic device, wherein the sealed body for an electronic device is formed by sealing the electronic device with a cured adhesive layer, wherein the cured adhesive layer is a cured product of a sheet-shaped adhesive as described in any one of [1] to [5]. [8] A sealed body for an electronic device as described in [7], wherein the sealed body for an electronic device is a light-related device. [9] A method for manufacturing a sealed body for an electronic device, comprising the following steps (b1) to (b2). Step (b1): irradiating the sheet-shaped adhesive as described in any one of [1] to [5] or the adhesive layer of the sealing sheet as described in [6] with ultraviolet light to initiate a curing reaction. Step (b2): a step of attaching the sheet adhesive or adhesive layer after step (b1) to an electronic device. [Effect of the invention]

According to the present invention, there can be provided a sheet adhesive suitable for use as a material for forming a cured product having excellent shape retention under high temperature conditions, a sealing sheet having the sheet adhesive, a sealed body of an electronic device formed by sealing an electronic device with the cured product of the sheet adhesive, and a method for manufacturing a sealed body of an electronic device.

[Form of implementing the invention]

The present invention is described in detail below according to 1) a sheet adhesive, 2) a sealing sheet, and 3) a sealing body of an electronic device and a method for manufacturing the same.

1) Sheet adhesive The sheet adhesive of the present invention comprises the following components (A), (B), and (C). Component (A): phenoxy resin having a glass transition temperature (Tg) of 110°C or higher Component (B): multifunctional epoxy resin Component (C): photopolymerization initiator

The sheet adhesive refers to an adhesive that is non-fluid at room temperature (25°C) and is formed into a sheet. In the present invention, the sheet adhesive may be in a thin and long shape or in a long strip (ribbon shape).

[Component (A)] The sheet adhesive of the present invention contains a phenoxy resin having a glass transition temperature (Tg) of 110°C or higher as component (A) (hereinafter referred to as "phenoxy resin (A)").

Phenoxy resin is a polymer with a main chain structure of an addition polymerization of aromatic diols and aromatic diglycidyl ethers. Phenoxy resin is generally equivalent to a high molecular weight epoxy resin with a degree of polymerization of about 100 or more.

Since the sheet-shaped adhesive contains the phenoxy resin (A), the cured product of the sheet-shaped adhesive has excellent shape retention under high temperature conditions.

In addition, the phenoxy resin (A) is important for fully exerting the characteristics of the component (B). That is, as described later, from the viewpoint of the adhesion of the sheet adhesive and the shape retention of the cured product of the sheet adhesive under high temperature conditions, it is better to contain a large amount of the component (B) in the sheet adhesive. However, a sheet adhesive containing a large amount of the component (B) has a problem that the shape retention is easily deteriorated. In particular, a sheet adhesive containing the component (C) requires a long time until the curing reaction is completed. Therefore, in the case where such a sheet adhesive contains a large amount of the component (B), it is necessary to improve the shape retention. In this regard, since the sheet adhesive of the present invention contains the phenoxy resin (A), even in the case where the component (B) is contained in a large amount, it can maintain a certain shape for a long time.

The glass transition temperature (Tg) of the phenoxy resin (A) is 110°C or higher, preferably 120 to 180°C, and more preferably 140 to 165°C. Since the glass transition temperature (Tg) of the phenoxy resin (A) is 110°C or higher, the sheet adhesive can maintain a certain shape for a long time. Furthermore, the cured product of the sheet adhesive has excellent shape retention under high temperature conditions. The glass transition temperature (Tg) of the phenoxy resin (A) can be measured using a differential scanning calorimeter in accordance with JIS K 7121.

The weight average molecular weight (Mw) of the phenoxy resin (A) is generally 10,000 to 200,000, preferably 20,000 to 100,000, and more preferably 30,000 to 80,000. When the weight average molecular weight (Mw) of the phenoxy resin (A) is too small, the sheet adhesive tends to have difficulty in maintaining a certain shape. When the weight average molecular weight (Mw) of the phenoxy resin (A) is too large, the operability of the sheet adhesive tends to deteriorate. The weight average molecular weight (Mw) of the phenoxy resin (A) can be obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent to obtain a standard polystyrene conversion value.

The epoxy equivalent of the phenoxy resin (A) is preferably 5,000 g/eq or more, more preferably 7,000 g/eq or more. The epoxy equivalent value can be measured in accordance with JIS K7236.

Examples of phenoxy resins (A) include bisphenol A type phenoxy resins, bisphenol F type phenoxy resins, bisphenol S type phenoxy resins, copolymerized phenoxy resins of bisphenol A type and bisphenol F type, bisphenol E type phenoxy resins, naphthalene type phenoxy resins, phenol formaldehyde type phenoxy resins, biphenyl type phenoxy resins, cyclopentadiene type phenoxy resins, etc. These phenoxy resins (A) can be used alone or in combination of two or more.

The phenoxy resin (A) can be obtained by a method of reacting a difunctional phenol and epihalohydrin to a high molecular weight, or by a method of subjecting a difunctional epoxy resin and a difunctional phenol to addition polymerization. The phenoxy resin (A) can be obtained, for example, by reacting a difunctional phenol and epihalohydrin in an inert solvent at a temperature of 40 to 120°C in the presence of an alkaline metal hydroxide. Alternatively, the phenoxy resin (A) can be obtained by, for example, subjecting a difunctional epoxy resin and a difunctional phenol to an addition polymerization reaction in the presence of a catalyst such as an alkali metal compound, an organic phosphorus compound, a cyclic amine compound, etc., in an organic solvent such as an amide solvent, an ether solvent, a ketone solvent, a lactone solvent, an alcohol solvent, etc. having a boiling point of 120° C. or higher, with the reaction solid content concentration being 50% by weight or less, and heating at 50 to 200° C.

The difunctional phenols are not particularly limited as long as they are compounds having two phenolic hydroxyl groups. Examples of difunctional phenols include monocyclic difunctional phenols such as hydroquinone, 2-bromohydroquinone, resorcinol, and catechol; bisphenols such as bisphenol A, bisphenol F, bisphenol AD, and bisphenol S; dihydroxybiphenyls such as 4,4-dihydroxybiphenyl; and dihydroxybenzenes such as bis(4-hydroxyphenyl)ether. ethers; those having a straight chain alkyl group, branched chain alkyl group, aryl group, hydroxymethyl group, allyl group, cyclic aliphatic group, halogen (tetrabromobisphenol A, etc.), nitro group, etc. introduced into the aromatic ring of the phenol structure; those having a straight chain alkyl group, branched chain alkyl group, allyl group, substituted allyl group, cyclic aliphatic group, alkoxycarbonyl group, etc. introduced into the central carbon atom of the bisphenol structure; etc.

Epihalohydrins include epichlorohydrin, epibromohydrin, epiiodohydrin, etc.

In the present invention, commercially available phenoxy resins (A) may be used. Examples of commercially available phenoxy resins (A) include YX7200 (glass transition temperature: 150°C) and YX6954 (phenoxy resin containing a bisphenol acetophenone structure, glass transition temperature: 130°C) manufactured by Mitsubishi Chemical Corporation.

The content of the phenoxy resin (A) is preferably 15 to 47% by mass, and more preferably 25 to 45% by mass, relative to the total amount of the sheet adhesive. When the content of the phenoxy resin (A) is within the above range, the shape retention and adhesion of the sheet adhesive, and the shape retention of the cured product under high temperature conditions can be well-balanced.

[Component (B)] The sheet adhesive of the present invention contains a polyfunctional epoxy resin as component (B) (hereinafter referred to as polyfunctional epoxy resin (B)). “Polyfunctional” means having two or more epoxy groups in the molecule.

The weight average molecular weight (Mw) of the polyfunctional epoxy resin (B) is preferably 100 to 5,000, more preferably 200 to 4,000. The weight average molecular weight (Mw) of the polyfunctional epoxy resin (B) can be obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent to obtain a standard polystyrene conversion value.

The epoxy equivalent of the multifunctional epoxy resin (B) is preferably 100 g/eq or more and 500 g/eq or less, and more preferably 115 g/eq or more and 300 g/eq or less. By curing a sheet adhesive containing a multifunctional epoxy resin (B) having an epoxy equivalent of 100 g/eq or more and 500 g/eq or less, a cured product having excellent bonding strength can be obtained.

The content of the multifunctional epoxy resin (B) is preferably 50% by mass or more, more preferably 52 to 70% by mass, and even more preferably 55 to 68% by mass, relative to the entire sheet adhesive. Since the content of the multifunctional epoxy resin (B) is within the above range, the shape retention and adhesion of the sheet adhesive, and the shape retention of the cured product under high temperature conditions can be maintained in a well-balanced manner.

Examples of the polyfunctional epoxy resin (B) include aliphatic epoxy compounds (excluding alicyclic epoxy compounds), aromatic epoxy compounds, and alicyclic epoxy compounds.

Aliphatic epoxy compounds include, for example, 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, polypropylene glycol diglycidyl ether, dicyclopentadienyl dimethanol diglycidyl ether, and the like.

Aromatic epoxy compounds include, for example, bisphenol A, bisphenol F, or epoxypropyl ether compounds or epoxyphenolic resins of compounds further adding alkylene oxides thereto; polyoxypropyl ether compounds of aromatic compounds having two or more phenolic hydroxyl groups such as resorcinol, hydroquinone, or o-catechin; epoxypropyl ether compounds of aromatic compounds having two or more alcoholic hydroxyl groups such as phenyl dimethanol, phenyl diethanol, or phenyl dibutyl alcohol; epoxypropyl esters of polybasic acid aromatic compounds having two or more carboxylic acids such as phthalic acid, terephthalic acid, or trimellitic acid; and the like.

Alicyclic epoxy compounds include, for example, polyglycidyl ether compounds of polyols having at least one alicyclic structure such as hydrogenated products of bisphenol A, or cycloalkane oxide compounds such as cyclohexene oxide or cyclopentane oxide compounds obtained by epoxidizing cyclohexene or cyclopentene ring-containing compounds with an oxidizing agent.

These polyfunctional epoxy resins (B) may be used alone or in combination of two or more. From the viewpoint of preventing the sheet adhesive from discoloring, the polyfunctional epoxy resin (B) preferably contains an alicyclic epoxy compound.

At least one of the polyfunctional epoxy resins (B) is preferably the following (BL) component. (BL) component: a polyfunctional epoxy resin that is liquid at 25°C (hereinafter referred to as liquid polyfunctional epoxy resin (BL)) “Liquid at 25°C” means that it has fluidity at 25°C. The liquid polyfunctional epoxy resin (BL) preferably has a viscosity of 2 to 10,000 mPa․s at 25°C and 1.0 rpm measured using an E-type viscometer.

Sheet adhesives containing component (A) tend to have poor adhesion. However, since the sheet adhesive of the present invention contains a liquid multifunctional epoxy resin (BL), it has sufficient adhesion. In addition to the above effects, the liquid multifunctional epoxy resin (BL) forms a cured product with a high crosslinking density, and the cured product tends to have higher shape retention under high temperature conditions. Therefore, the sheet adhesive of the present invention is suitable for use as a material for forming a cured product with excellent shape retention under high temperature conditions.

The content of the liquid multifunctional epoxy resin (BL) is preferably 50% by mass or more, more preferably 52 to 70% by mass, and even more preferably 55 to 68% by mass, relative to the total sheet adhesive. Since the content of the liquid multifunctional epoxy resin (BL) is 50% by mass or more relative to the total sheet adhesive, a sheet adhesive with better adhesion can be obtained efficiently.

[Component (C)] The sheet adhesive of the present invention contains a photo-radical polymerization initiator as the component (C). The sheet adhesive containing the photo-radical polymerization initiator is excellent in general use. That is, since the sheet adhesive containing the photo-radical polymerization initiator tends to complete the curing reaction in a short time, the method of using the sheet adhesive containing the photo-radical polymerization initiator is generally limited to attaching the sheet adhesive to the object and then irradiating the sheet adhesive with light to cure it. On the other hand, the sheet adhesive of the present invention containing a photo-ion polymerization initiator requires time until the curing reaction is completed. Therefore, the sheet adhesive is not limited to being cured after being attached to an object. The sheet adhesive may be attached to an object after the curing reaction starts.

In addition, the characteristic of the time required for the curing reaction to be completed is that the sheet adhesive may deform during the curing reaction, which may cause the object to be unable to be fixed at the target position. In particular, the sheet adhesive containing a liquid multifunctional epoxy resin (BL) tends to have higher fluidity, which is prone to this problem. In this regard, the sheet adhesive of the present invention can maintain a certain shape until the curing reaction is completed even when containing a liquid multifunctional epoxy resin (BL), because it contains a phenoxy resin (A) with a high Tg, and can fix the object at the target position.

A photocationic polymerization initiator is a compound that generates cations upon exposure to ultraviolet light and initiates the curing reaction of a cationic curable compound. It is composed of a cationic portion that absorbs ultraviolet light and an anionic portion that becomes a source of acid generation.

Examples of the photocatalytic polymerization initiator include sulfonium salt compounds, iodonium salt compounds, phosphonium salt compounds, ammonium salt compounds, antimonate compounds, diazonium salt compounds, selenium salt compounds, oxonium salt compounds, and bromate compounds. Among these, sulfonium salt compounds are preferred, and aromatic sulfonium salt compounds having an aromatic group are more preferred, from the viewpoint of excellent compatibility with other components.

Copper salt compounds such as triphenylcopperium hexafluorophosphate, triphenylcopperium hexafluoroantimonate, triphenylcopperium tetrakis(pentafluorophenyl)borate, 4,4'-bis[diphenyldihydrothio]diphenyl sulfide-bis(hexafluorophosphate), 4,4'-bis[bis(β-hydroxyethoxy)phenyldihydrothio]diphenyl sulfide-bis(hexafluoroantimonate), 7-[ [Bis(p-methylphenyl)dihydrothio]-2-isopropylthiothione hexafluorophosphate, 7-[Bis(p-methylphenyl)dihydrothio]-2-isopropylthiothione hexafluoroantimonate, 7-[Bis(p-methylphenyl)dihydrothio]-2-isopropyltetrakis(pentafluorophenyl)borate, phenylcarbonyl-4'-diphenyldihydrothio -diphenyl sulfide-hexafluorophosphate, phenylcarbonyl-4'-diphenyl dihydrosulfide-diphenyl sulfide-hexafluoroantimonylate, 4-tert-butylphenylcarbonyl-4'-diphenyl dihydrosulfide-diphenyl sulfide-hexafluoroantimonylate, 4-tert-butylphenylcarbonyl-4'-diphenyl dihydrosulfide-diphenyl sulfide-hexafluoroantimonylate, 4-tert-butylphenylcarbonyl-4'-diphenyl dihydrosulfide-diphenyl sulfide-tetrakis(pentafluorophenyl)boric acid, 4-(phenylthio)phenyldiphenylarsium hexafluoroantimonylate, 4-(phenylthio)phenyldiphenylarsium hexafluorophosphate, 4-{4-(2-chlorobenzyl)phenylthio}phenylbis(4-fluorophenyl) Copper hexafluoroantimonylate, thiophenyl diphenyl copper hexafluoroantimonylate halide, 4,4',4''-tris(β-hydroxyethoxyphenyl) copper hexafluoroantimonylate, 4,4'-bis[diphenyl dihydrothio] diphenyl sulfide-bishexafluoroantimonylate, diphenyl[4-(phenylthio)phenyl] copper trifluorothiophene pentafluoroethyl phosphate, tris(4-(4-acetylphenylhydrothio)phenyl] copper tris(trifluoromethyl)sulfonyl]methanide, salts of phosphorus anions to which 4-(phenylthio)phenyl diphenyl copper is added as the cation part and fluorine and perfluoroalkyl are added as the anion part, etc.

Iodine salt compounds include, for example, diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di(4-nonylphenyl)iodonium hexafluorophosphate, (triisopropylphenyl)iodonium tetrakis(pentafluorophenyl)borate, and the like.

Phosphonium salt compounds include tri-n-butyl (2,5-dihydroxyphenyl) phosphonium bromide and hexadecyltributylphosphonium chloride.

Ammonium salt compounds include benzyltrimethylammonium chloride, phenyltributylammonium chloride, benzyltrimethylammonium bromide, etc.

Examples of the antimonate compounds include triphenylcopperium hexafluoroantimonate, p-(phenylthio)phenyldiphenylcopperium hexafluoroantimonate, 4-chlorophenyldiphenylcopperium hexafluoroantimonate, bis[4-(diphenyldihydrothio)phenyl]sulfide bis(hexafluoroantimonate), and diallyliodonium hexafluoroantimonate.

These photocatalytic polymerization initiators may be used alone or in combination of two or more.

As the photopolymerization initiator, a commercial product may be used. Examples of the commercial products include Syracure UVI-6970, Syracure UVI-6974, Syracure UVI-6990, Syracure UVI-950 (all manufactured by Union Carbide), Irgacure 250, Irgacure 261, Irgacure 264 (all manufactured by Ciba Specialty Chemicals), SP-150, SP-151, SP-170, Optomer SP-171 (all manufactured by ADEKA), CG-24-61 (manufactured by Ciba Specialty Chemicals), DAICAT II (manufactured by Daicel), UVAC 1590, UVAC 1591 (above, made by Daicel˙Citech Co., Ltd.), CI-2064, CI-2639, CI-2624, CI-2481, CI-2734, CI-2855, CI-2823, CI-2758, CIT-1682 (above, made by Japan Soda Co., Ltd.), PI-2074 (made by Rhodia Co., Ltd.), FFC509 (manufactured by 3M Co., Ltd.), BBI- 102, BBI-101, BBI-1 03, MPI-103, TPS-103, MDS-103, DTS-103, NAT-103, NDS-103 (all manufactured by Midori Chemical Co., Ltd.), CD-1010, CD-1011, CD-1012 (manufactured by Sartomer), CPI-100P, CPI-101A, CPI-200K, CPI-310B (all manufactured by San-apro), San-aid SI-60, San-aid SI-80, San-aid SI-100, San-aid SI-110, San-aid SI-150 (all manufactured by Sanshin Chemical Industry Co., Ltd.), etc.

The content of the photocatalytic ion polymerization initiator is usually 0.1 to 10 parts by mass, preferably 0.3 to 8 parts by mass, and more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of the component (B).

[Component (D)] The sheet adhesive of the present invention preferably contains a silane coupling agent having a long-chain spacer group as the component (D) (hereinafter referred to as "silane coupling agent (D)"). The cured product of the sheet adhesive containing the silane coupling agent (D) has a better bonding strength.

The silane coupling agent is a silane compound having a silicon atom, a functional group, and a hydrolyzable group bonded to the silicon atom.

The long-chain spacer group is a divalent group connecting the silicon atom and the functional group, and the number of atoms constituting the main chain is 3 or more. The number of atoms constituting the main chain is preferably 3 to 12, and more preferably 6 to 10. Examples of long-chain spacer groups include polymethylene groups such as trimethylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, and dodecylene.

Functional groups are groups that are reactive with other compounds (mainly organic substances). Examples of functional groups include vinyl, allyl, epoxy, glycidoxy, 3,4-epoxycyclohexyl, amine, substituted amine, acrylic, methacrylic, mercapto, isocyanate, and groups with anhydride structures. Among these, groups with cyclic ether structures such as epoxy, glycidoxy, and 3,4-epoxycyclohexyl are preferred from the perspective of easily obtaining a cured product with excellent shape retention under high temperature conditions.

Examples of the "hydrolyzable group" include alkoxy groups such as methoxy and ethoxy groups; halogen atoms such as chlorine and bromine atoms; and the like.

The silane coupling agent (D) is exemplified by the compound represented by the following formula.

[Chemistry 1]

^R1 represents a functional group, and ^R2 represents an alkyl group having 1 to 5 carbon atoms. A plurality of ^R2 groups may be the same or different. x represents an integer greater than 6. The functional group of ^R1 is, for example, the above-mentioned alkyl group. The alkyl group having 1 to 5 carbon atoms of ^R2 is, for example, a methyl group, an ethyl group, etc. x is an integer greater than 3, preferably an integer of 3 to 12, and more preferably an integer of 6 to 10.

Specific examples of the silane coupling agent (D) include 8-glycidoxy octyl trimethoxy silane, 8-glycidoxy octyl triethoxy silane, 8-acryloyloxy octyl trimethoxy silane, 8-acryloyloxy octyl triethoxy silane, 8-methacryloyloxy octyl trimethoxy silane, 8-methacryloyloxy octyl triethoxy silane, 8-vinyl octyl trimethoxy silane, and 8-vinyl octyl triethoxy silane. The silane coupling agent (D) may be used alone or in combination of two or more.

When the sheet adhesive contains a silane coupling agent (D), the content of the silane coupling agent (D) is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 3 parts by mass, based on 100 parts by mass of the component (B).

[Other components] The sheet adhesive of the present invention may contain other components within the range that does not hinder the effect of the present invention. Other components include additives such as silane coupling agents other than silane coupling agent (D), ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders, and softeners. These may be used alone or in combination of two or more. In the case where the sheet adhesive of the present invention contains these additives, the content thereof may be appropriately determined according to the purpose.

[Sheet adhesive] The thickness of the sheet adhesive of the present invention is usually 1 to 50 μm, preferably 2 to 40 μm, and more preferably 5 to 30 μm. The sheet adhesive having a thickness within the above range is suitable for use as a material for forming a sealant. The thickness of the sheet adhesive can be measured using a known thickness meter in accordance with JIS K 7130 (1999). In addition, in the case where the sheet adhesive has a release film described later, the thickness of the sheet adhesive is the thickness minus the thickness of the release film.

From the viewpoint of protecting the sheet adhesive from the external environment, it is preferred that at least one surface of the sheet adhesive has a release film, and both surfaces may have release films.

In addition, the sheet adhesive of the present invention having a release film on at least one surface is a state before use. When using the sheet adhesive of the present invention, the release film is usually peeled off. In the case where the sheet adhesive has release films on both sides, the release film with a low release force is usually peeled off first.

The peeling film can generally be made of a resin film. The resin component of the resin film includes, for example, polyimide, polyamide, polyamide imide, polyphenylene ether, polyether ketone, polyether ether ketone, polyolefin, polyester, polycarbonate, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, acrylic resin, cycloolefin polymer, aromatic polymer, polyurethane polymer, etc. Among these, polyester resin is preferred.

When the stripping film has a stripping agent layer, the stripping agent is, for example, a rubber elastomer such as silicone resin, olefin resin, isoprene resin, butadiene resin, etc.; a long-chain alkyl resin, acid alcohol resin, fluororesin, etc.

The thickness of the peeling film is usually 10 to 300 μm, preferably 10 to 200 μm, and more preferably 15 to 100 μm.

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

The method of manufacturing a sheet adhesive by casting is to apply an adhesive composition on a release film using a known method, and then dry the obtained coating to obtain a sheet adhesive with a release film.

The adhesive composition can be prepared by mixing and stirring the above-mentioned (A) component, (B) component, and (C) component, and other components as needed, by a known method. When a solvent is used in the preparation of the adhesive composition, the viscosity of the adhesive composition can be appropriately adjusted by the amount of the solvent used.

Solvents include aliphatic hydrocarbon solvents such as n-hexane and n-heptane; aromatic hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as dichloromethane, vinyl chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, and monochlorobenzene; alcohol solvents such as methanol, ethanol, propanol, butanol, and propylene glycol monomethyl ether; ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; cellosolve solvents such as ethyl cellosolve; ether solvents such as 1,3-dioxolane; etc. These solvents can be used alone or in combination of two or more. The content of the solvent can be appropriately determined in consideration of coating properties, film thickness, etc.

The peeling film used in the production of the sheet-like adhesive functions as a support during the production step of the sheet-like adhesive and also functions as a peeling film of the sheet-like adhesive until the sheet-like adhesive is used.

The adhesive composition may be applied by, for example, rotary coating, spray coating, rod coating, knife coating, roller coating, scraper coating, nozzle coating, gravure coating, etc.

The method of drying the coating of the adhesive composition is, for example, a known drying method such as hot air drying, hot roller drying, infrared irradiation, etc. The conditions for drying the coating are, for example, 80 to 150°C for 30 seconds to 5 minutes.

The sheet adhesive of the present invention can be cured by irradiation with ultraviolet rays. Specific examples of ultraviolet light sources include ultrahigh pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, metal halogen lamps, and the like. In addition, the wavelength of ultraviolet light used for irradiation can be in the wavelength range of 190 to 380 nm. The type of ultraviolet light, the irradiation amount, the irradiation time, etc. can be appropriately determined according to the components of the sheet adhesive to be irradiated or the content of each component. The irradiation illumination is preferably about 20 to 1000 mW/cm ² , and the light quantity is about 50 to 3000 mJ/cm ² .

The storage elasticity of the cured product of the sheet adhesive of the present invention at 80°C is preferably 500 MPa or more, more preferably 800 to 3000 MPa, and even more preferably 1200 to 2500 MPa. A cured product having a storage elasticity of 500 MPa or more at 80°C is difficult to deform even under high temperature conditions. Therefore, such a cured product can be preferably used as a sealing material whose performance is not reduced in most cases under high temperature conditions. The storage elasticity of the cured product at 80°C can be measured according to the method described in the embodiment.

Due to the above-mentioned characteristics, the sheet adhesive of the present invention is suitable for use as a material for forming a sealant for electronic devices. Electronic devices include various components that constitute the sealant of the electronic device described later. Various components include organic EL components, liquid crystal components, electronic book components, etc.

2) Sealing sheet The sealing sheet of the present invention has an adhesive layer formed by the sheet-shaped adhesive of the present invention and a functional film.

Functional films include conductive films, gas barrier films, anti-reflection films, phase difference films, viewing angle improvement films, and brightness enhancement films. Among these, for example, gas barrier films, such as thin films with metal or inorganic compound films, and thin films with metal films are preferred. The metals used include aluminum, zinc, copper, etc., and aluminum is preferred. The thickness of the functional film used in the present invention is not particularly limited, and is usually 5 to 200 μm, preferably 10 to 100 μm. When the functional film is a thin film with a metal or inorganic compound film, the functional film is difficult for ultraviolet rays to pass through. Such a functional film usually has a transmittance of less than 60% for ultraviolet rays at a wavelength of 365 nm. In the case where the functional film is difficult for ultraviolet rays to pass through, the advantages of the manufacturing method (β) described below become significant. From such a viewpoint, when a sealed body of an electronic device is produced using the production method (β), the transmittance of the functional film at ultraviolet light of a wavelength of 365 nm is preferably 55% or less, and more preferably 50% or less.

The sealing sheet of the present invention preferably has at least the above-mentioned functional film and an adhesive layer formed by the sheet-shaped adhesive of the present invention. The functional film may be one layer or two or more layers. Furthermore, the adhesive layer may be one layer or two or more layers. When the functional film is a metal or inorganic compound film and a gas barrier film having a resin film, in order to prevent water vapor invading from the end of the resin film from moving to the sealed device, the adhesive layer is arranged on the side of the film closer to the metal or inorganic compound than the resin film, so that the adhesive layer and the resin film are separated by a metal or inorganic compound film.

The sealing sheet of the present invention may also have other layers. Other layers include, for example, a primer layer that improves the adhesion of the interface between the adhesive layer and the functional film, a functional coating layer or protective film provided on the surface of the functional film without the adhesive layer, an antistatic layer or stress relief layer formed on both surfaces of the functional film, etc.

The thickness of the sealing sheet of the present invention is usually 6 to 270 μm. The thickness of the sealing sheet is the thickness after deducting the thickness of the components removed before use of the peeling film, protective film, etc.

The sealing sheet of the present invention can be produced, for example, by laminating the sheet-shaped adhesive of the present invention and a functional film.

3) Sealed body of electronic device The sealed body of the electronic device of the present invention is an electronic device sealed by a cured adhesive layer of a cured adhesive of the sheet-shaped adhesive of the present invention.

The electronic device is exemplified above. The adhesive cured layer is formed by curing the sheet-shaped adhesive of the present invention. The adhesive cured layer may also be formed by curing the adhesive layer of the sealing sheet of the present invention.

The cured product of the sheet adhesive of the present invention can be easily made colorless and transparent. Due to this characteristic, the sealed body of the electronic device is preferably a light-emitting device, a light-receiving device, a display device, and other light-related devices. Light-related devices include organic EL displays, organic EL lighting, liquid crystal displays, electronic books, and the like. The sealed body of the electronic device is preferably a display device such as an organic EL display, a liquid crystal display, an electronic book, and the like.

The sealed body of the electronic device can be manufactured by a manufacturing method (α) having the following steps (a1) to (a2) or a manufacturing method (β) having the following steps (b1) to (b2).

[Manufacturing method (α)] Step (a1): a step of attaching the sheet adhesive of the present invention or the adhesive layer of the sealing sheet of the present invention to an electronic device to manufacture a laminate. Step (a2): a step of irradiating the sheet adhesive or the adhesive layer in the laminate obtained in step (a1) with ultraviolet rays.

The manufacturing method (α) is to start the curing reaction of the sheet adhesive after the sheet adhesive is attached to the electronic device. After the curing reaction started according to step (a2) is completed, the known steps can be performed to manufacture the sealing body of the target electronic device. The manufacturing method (α) is suitable for use in manufacturing the sealing body of the electronic device with good productivity.

[Manufacturing method (β)] Step (b1): irradiating the sheet adhesive of the present invention or the adhesive layer of the sealing sheet of the present invention with ultraviolet light to start a curing reaction. Step (b2): attaching the sheet adhesive or adhesive layer after step (b1) to an electronic device before the curing reaction is completed.

The manufacturing method (β) is to attach the sheet adhesive to the electronic device after the curing reaction of the sheet adhesive starts and before the curing reaction ends. After step (b2) and after the curing reaction started by step (b1) ends, the known steps can be performed to manufacture the sealed body of the target electronic device. The sheet adhesive of the present invention is one that starts the curing reaction by a photo-cationic ion polymerization initiator, and it takes a certain amount of time until the curing reaction ends. Therefore, the sealed body of the electronic device can be manufactured by the manufacturing method (β). Manufacturing method (β) is preferably used in situations where the electronic device may malfunction due to ultraviolet irradiation, or when the sealing sheet is located on the outer side of the adhesive layer (the side away from the attached electronic device), or when a layer having ultraviolet shielding properties exists in the functional film or the like. [Example]

The present invention is further described in detail with the following embodiments. However, the present invention is not limited to the following embodiments.

[Compounds used in the Examples or Comparative Examples] ˙Phenoxy resin (A1): (Mitsubishi Chemical Co., Ltd., trade name: YX7200B35, glass transition temperature: 150°C) ˙Phenoxy resin (A2): (Mitsubishi Chemical Co., Ltd., trade name: YX6954BH30, glass transition temperature: 130°C) ˙Phenoxy resin (X): ( Mitsubishi Chemical Co., Ltd., trade name: 4250, glass transition temperature: 78°C) ˙Liquid multifunctional epoxy resin (BL1): Hydrogenated bisphenol A type epoxy resin [Mitsubishi Chemical Co., Ltd., trade name: YX8000, epoxy equivalent: 205 g/eq] ˙Liquid multifunctional epoxy resin (BL2): 3',4'-epoxycyclohexylmethyl 3,4 -Epoxycyclohexanecarboxylate [manufactured by Daicel Co., Ltd., trade name: Celloxide 2021P, epoxy equivalent: 128-145 g/eq] ˙Photocatalytic polymerization initiator (C1): 4-(phenylthio)phenyl diphenylphosphine hexafluorophosphate [manufactured by San-apro Co., Ltd., trade name: CPI-100P] ˙Photocatalytic polymerization Initiator (C2): 4-(phenylthio)phenyldiphenylsilane as the cationic part, and a salt of a phosphorus anion to which fluorine and perfluoroalkyl groups are added as the anionic part [made by San-apro, trade name: CPI-200K] Silane coupling agent (D1): 8-glycidoxyoctyltrimethoxysilane (made by Shin-Etsu Chemical Co., Ltd., trade name: KBM4803)

[Example 1] 100 parts by mass of phenoxy resin (A1) (calculated after deducting the active ingredient of the solvent, the same below), 170 parts by mass of liquid multifunctional epoxy resin (BL1), 5 parts by mass of photocatalytic polymerization initiator (C1), and 0.1 parts by mass of silane coupling agent (D1) were diluted with methyl ethyl ketone to prepare a resin composition (1) having an active ingredient concentration of 50%. The resin composition (1) was applied to the peeling treatment surface of a peeling film (manufactured by Lintec, trade name: SP-PET752150), and the resulting coating was dried at 100°C for 2 minutes to form a sheet adhesive with a thickness of 20 μm. On top of this sheet-like adhesive, the release-treated surface of another release film (manufactured by Lintec, trade name: SP-PET381031) was laminated to produce a sheet-like adhesive with a release film (1).

[Example 2] In Example 1, except that 120 parts by weight of liquid multifunctional epoxy resin (BL2) was used instead of liquid multifunctional epoxy resin (BL1), the rest was the same as in Example 1 to prepare a sheet adhesive (2) with a release film.

[Example 3] In Example 1, except that 3 parts by weight of photo-cationic polymerization initiator (C2) is used instead of photo-cationic polymerization initiator (C1), the rest is the same as Example 1 to prepare a sheet adhesive (3) with a release film.

[Example 4] Example 1 is the same as Example 1 except that 100 parts by weight of phenoxy resin (A2) is used instead of phenoxy resin (A1), and the rest is the same as Example 1 to prepare a sheet adhesive (4) with a release film.

[Example 5] In Example 1, except that the content of the liquid multifunctional epoxy resin (BL1) was changed to 100 parts by weight, the rest was the same as in Example 1 to prepare a sheet adhesive (5) with a release film.

[Comparative Example 1] In Example 1, except that 100 parts by weight of phenoxy resin (X) was used instead of phenoxy resin (A1), the rest was the same as in Example 1 to prepare a sheet adhesive (6) with a release film.

The following tests were conducted on the sheet-shaped adhesives (1) to (6) with release films obtained in Examples 1 to 5 and Comparative Example 1. The results are shown in Table 1.

(Evaluation of adhesion of sheet adhesive) The sheet adhesive obtained in the embodiment or comparative example was laminated on glass at 23°C and 0.2 MPa using a laminator. The sheet adhesive was visually observed. If no peeling occurred, it was evaluated as ○. If peeling occurred in at least a part, it was evaluated as ×.

(Storage elasticity of cured product of sheet adhesive) The sheet adhesive obtained in the embodiment or comparative example was laminated at 23°C and 0.2 MPa using a laminator to obtain a laminate with a thickness of 200 μm. The laminate was irradiated with ultraviolet light using a high-pressure mercury lamp manufactured by Eyegraphics at an illumination of 200 mW/ ^cm2 and an integrated light quantity of 2000 mJ/ ^cm2 . The light quantity meter used was "UVPF-A1" manufactured by Eyegraphics. Thereafter, the laminate was heated at 100°C for 2 hours to promote the reaction. The laminate after the curing reaction was used as a sample, and the storage modulus was measured using a storage modulus measuring device (manufactured by TA Instruments, trade name: DMAQ 800) in the tensile mode, with a frequency of 1 Hz and an amplitude of 5 μm. The temperature was increased at 3°C/min and the measurement was performed in the range of -20 to 150°C. The measurement results at 80°C are shown in Table 1.

[Table 1] Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparison Example 1 Ingredients (Quality) Phenoxy resin (A1) (Tg: 150℃) 100 100 100 - 100 - Phenoxy resin (A2) (Tg: 130℃) - - - 100 - - Phenoxy resin (X) (Tg:78℃) - - - - - 100 Liquid multifunctional epoxy resin (BL1) 170 - 170 170 100 170 Liquid multifunctional epoxy resin (BL2) - 120 - - - - Photocatalytic polymerization initiator (C1) 5 5 - 5 5 5 Photocatalytic polymerization initiator (C2) - - 3 - - - Silane coupling agent (D1) 0.1 0.1 0.1 0.1 0.1 0.1 Storage elasticity of cured sheet adhesive (MPa) 1549 2356 1662 1658 957 247 Adhesion of sheet adhesive ○ ○ ○ ○ × ○

The following can be seen from Table 1. The cured products of the sheet adhesives (1) to (5) obtained in Examples 1 to 5 have excellent shape retention under high temperature conditions. Comparing Examples 1 to 5 with Comparative Example 1, it can be seen that the glass transition temperature of the phenoxy resin affects the shape retention of the cured product under high temperature conditions. In addition, comparing Examples 1 to 4 with Example 5, it can be seen that the adhesion of the sheet adhesive and the shape retention of the cured product under high temperature conditions are improved when a large amount of liquid multifunctional epoxy resin (BL) is contained.

without.

without.

without.

Claims (8)

A sheet adhesive comprises the following (A) component, (B) component, and (C) component, (A) component: phenoxy resin having a glass transition temperature (Tg) of 130°C or higher, (B) component: multifunctional epoxy resin, (C) component: photocatalytic polymerization initiator, wherein at least one of the (B) components is the following (BL) component: (BL) component: multifunctional epoxy resin that is liquid at 25°C, wherein the content of the (BL) component is 50% by mass or more relative to the total sheet adhesive. The sheet adhesive as described in claim 1 further comprises the following (D) component, (D) component: a silane coupling agent having a long-chain spacer group, wherein the long-chain spacer group is a divalent group connecting the silicon atom and the functional group, and the number of atoms constituting the main chain is 3 or more. The sheet adhesive as described in claim 1 has a storage elasticity of 500 MPa or more at 80°C after curing. The sheet adhesive as described in claim 1 is used for sealing electronic devices. A sealing sheet having an adhesive layer formed by a sheet-shaped adhesive as described in any one of claims 1 to 4, and a functional film. A sealed body of an electronic device, which is a sealed body of an electronic device formed by sealing the electronic device with a cured adhesive layer, wherein the cured adhesive layer is a cured sheet adhesive as described in any one of claim items 1 to 4. The sealed body of an electronic device as described in claim 6, wherein the sealed body of the electronic device is a light-related device. A method for manufacturing a sealed body of an electronic device comprises the following steps (b1) to (b2), Step (b1): irradiating the sheet adhesive as described in any one of claim items 1 to 4, or the adhesive layer of the sealing sheet as described in claim item 5, with ultraviolet light to start a curing reaction, Step (b2): attaching the sheet adhesive or adhesive layer after step (b1) to an electronic device.