WO2020251030A1 - Device sealing adhesive sheet - Google Patents

Abstract

The present invention provides a device sealing adhesive sheet that has a first release film, a second release film, and an adhesive layer that is held between the first release film and the second release film, said device sealing adhesive sheet satisfying a requirement (I) and a requirement (II). A device sealing adhesive sheet according to the present invention has an adhesive layer having a superior stickability at a normal temperature and release films and is superior in terms of the peelability of the release films. Requirement (I): the adhesive layer contains one or more types of compounds having a cyclic ether group. Requirement (II): the storage modulus of the adhesive layer at 23ºC is 9.5×10⁵ to 3.0×10⁷ Pa.

Description

Adhesive sheet for device encapsulation

The present invention relates to an adhesive sheet for device encapsulation, which has an adhesive layer and a release film having excellent adhesiveness at room temperature (referred to as 23 ° C., the same applies hereinafter) and has excellent release property of the release film.

In recent years, an organic EL element has attracted attention as a light emitting element capable of high-luminance light emission by low-voltage direct current drive.
However, the organic EL element has a problem that the light emitting characteristics such as the light emitting brightness, the light emitting efficiency, and the light emitting uniformity tend to deteriorate with the passage of time.
It is considered that oxygen, water, etc. infiltrate into the inside of the organic EL element and deteriorate the electrode and the organic layer as a cause of the problem of deterioration of the light emitting characteristics. Therefore, it has been proposed to form a sealing material by using an adhesive layer or an adhesive layer having excellent moisture blocking properties to solve this problem.

For example, Patent Document 1 describes a sheet-like sealing material containing a specific epoxy resin, a specific alicyclic epoxy compound, a thermal cationic polymerization initiator, a photocationic polymerization initiator, and a specific sensitizer. ing.
The sealing material formed by using the sheet-shaped sealing material described in Patent Document 1 has low oxygen permeability and water permeability, and has good sealing performance.

JP-A-2018-95679

As described in Patent Document 1, a sheet-shaped sealing material utilizing the reactivity of a cyclic ether group has been suitably used as a material for forming a sealing material.
However, some of such sheet-shaped sealing materials are inferior in stickability at room temperature, and some of them need to be heated to soften the surface when sticking to the object to be sealed.
On the other hand, some of the sheet-shaped sealing materials having good stickability at room temperature were inferior in workability at the time of sticking.
That is, when the sheet-shaped sealing material (hereinafter, sometimes referred to as "adhesive layer") sandwiched between the two release films is cut into a predetermined shape, the adhesive layer is deformed by pushing the punching blade. In some cases, the release film could not be peeled off efficiently because the adhesive adhered to the unpeeled portion (cut surface) of the end portion of the release film.

The present invention has been made in view of the above circumstances, and provides an adhesive sheet for device encapsulation, which has an adhesive layer having excellent adhesiveness at room temperature and a release film, and has excellent releaseability of the release film. With the goal.

In order to solve the above problems, the present inventors have two release films and an adhesive layer sandwiched between these release films, and the adhesive layer contains a compound having a cyclic ether group. We diligently examined the adhesive sheet for sealing.
as a result,
(A) The adhesive layer having a storage elastic modulus at 23 ° C. or less is excellent in stickability at room temperature, and (b) peeling from the adhesive layer having a storage elastic modulus at 23 ° C. of a predetermined value or more. The adhesive sheet with the film has excellent peelability of the release film.
The present invention has been completed.

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

[1] An adhesive sheet for device encapsulation having a first release film and a second release film and an adhesive layer sandwiched between the first release film and the second release film, and the following requirement (I). And an adhesive sheet for device encapsulation that meets requirement (II).
Requirement (I): The adhesive layer is a layer containing one or more compounds having a cyclic ether group.
Requirement (II): The storage elastic modulus of the adhesive layer at 23 ° C. is 9.5 × 10 ⁵ Pa or more and 3.0 × 10 ⁷ Pa or less.
[2] The adhesive sheet for device encapsulation according to [1], wherein at least one of the compounds having a cyclic ether group is a compound that is liquid at 25 ° C.
[3] The adhesive sheet for device encapsulation according to [2], wherein the content of the compound having a cyclic ether group, which is liquid at 25 ° C., is 53% by mass or more with respect to the entire adhesive layer.
[4] The device-sealing adhesive according to [2] or [3], wherein the content of the compound having a cyclic ether group, which is liquid at 25 ° C., is 65% by mass or less with respect to the entire adhesive layer. Sheet.
[5] The device seal according to any one of [1] to [4], wherein the adhesive layer further contains a curing agent, and at least one of the curing agents is a thermal cationic polymerization initiator. Adhesive sheet for stopping.
[6] The adhesive sheet for device encapsulation according to [5], wherein all of the curing agents are thermal cationic polymerization initiators.
[7] The adhesive sheet for device encapsulation according to [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 encapsulation according to any one of [5] to [7], wherein at least one of the compounds having a cyclic ether group is an alicyclic epoxy resin.
[9] Of [1] to [8], wherein the adhesive layer contains a binder resin, and at least one of the binder resins is a binder resin having a glass transition temperature (Tg) of 60 ° C. or higher. Adhesive sheet for device encapsulation according to any one.
[10] The device-sealing adhesive according to any one of [1] to [9], wherein the layer obtained by curing the adhesive layer has a storage elastic modulus of 1 × 10 ⁸ Pa or more at 90 ° C. Sheet.
[11] The device sealing adhesive sheet according to any one of [1] to [10], which is used for forming a sealing material in an optical device.

According to the present invention, there is provided an adhesive sheet for device encapsulation which has an adhesive layer and a release film having excellent adhesiveness at room temperature and has excellent release property of the release film.

The device-sealing adhesive sheet of the present invention is a device-sealing adhesive sheet having a first release film and a second release film and an adhesive layer sandwiched between the first release film and the second release film. Therefore, the above requirements (I) and (II) are satisfied.

In the present invention, the "first release film" refers to a release film that is peeled off after the "second release film" when the adhesive sheet for device encapsulation is used, and the "second release film" refers to the device encapsulation. A release film that is peeled off first when the adhesive sheet for use is used.
Therefore, when the peeling forces of the two release films are different, the "first release film" usually refers to the one having the highest release force among the two release films, and the "second release film" is two sheets. A release film with a low release force.
The "adhesive layer" is a coating film of a curable adhesive, and is a layer having curability and adhesiveness. That is, the "adhesive layer" is a layer in an uncured state.
In the present specification, the "layer obtained by curing the adhesive layer" may be referred to as an "adhesive cured product layer". This adhesive cured product layer is used as a sealing material.
In the present invention, "curing" means that the cyclic ether groups contained in the adhesive layer react with each other to increase the cohesive force and storage elastic modulus of the layer.

[Adhesive layer]
(Compound having a cyclic ether group)
The adhesive layer contains one or more compounds having a cyclic ether group (hereinafter, may be referred to as "cyclic ether compound (A)").
By curing the adhesive layer containing the cyclic ether compound (A), it is possible to form a sealing material having high adhesive strength and excellent water vapor blocking property.

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 phenoxy resin described later is not included in the cyclic ether compound (A).

The molecular weight of the cyclic ether compound (A) is usually 100 to 5,000, preferably 200 to 3,000.
The cyclic ether equivalent of the cyclic ether compound (A) is preferably 50 to 1000 g / eq, more preferably 100 to 800 g / eq.
By curing the adhesive layer containing the cyclic ether compound (A) having a cyclic ether equivalent in the above range, it is possible to more efficiently form a sealing material having higher adhesive strength and better moisture blocking property.
The cyclic ether equivalent in the present invention means a value obtained by dividing the molecular weight by the number of cyclic ether groups.

Examples of the cyclic ether group include an oxylan group (epoxy group), an oxetane group (oxetanyl group), a tetrahydrofuryl group, a tetrahydropyranyl group and the like. Among these, the cyclic ether group is preferably an oxylan group or an oxetane group, and more preferably an oxylan group, from the viewpoint of being able to form a sealing material having higher adhesive strength.
Further, for the same reason, the cyclic ether compound (A) preferably has two or more oxylan groups or oxetane groups in the molecule, and more preferably has two or more oxylan groups in the molecule.

Examples of the compound having an oxylan group in the molecule include an aliphatic epoxy compound (excluding an alicyclic epoxy compound), an aromatic epoxy compound, and an alicyclic epoxy compound.
Examples of the aliphatic epoxy compound include monofunctional epoxy compounds such as glycidyl etherified products of aliphatic alcohols and glycidyl esters of alkylcarboxylic acids;
Examples thereof include polyglycidyl etherified products of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and polyfunctional epoxy compounds such as polyglycidyl esters of aliphatic long-chain polybasic acids.

Representative compounds of these aliphatic epoxy compounds include alkenyl glycidyl ethers such as allyl glycidyl ethers; alkyl glycidyl ethers such as butyl glycidyl ethers, 2-ethylhexyl glycidyl ethers, and C12-13 mixed alkyl glycidyl ethers; 1,4- Butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, tetraglycidyl ether of sorbitol, hexaglycidyl ether of dipentaerythritol, diglycidyl ether of polyethylene glycol, polypropylene glycol Glycidyl ethers of polyhydric alcohols such as diglycidyl ethers; polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as propylene glycol, trimethylolpropane and glycerin. Polyglycidyl ethers; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of aliphatic higher alcohols, glycidyl esters of higher fatty acids, epoxidized soybean oil, octyl epoxidate stearate, butyl epoxy stearate, epoxidized polybutadiene; And so on.

A commercially available product 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-611, 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 ( (Made 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 Kagakusha);
ADEKA Glycyrrol ED-503, Adeka Glycyrrol ED-503G, Adeka Glycyrrol ED-506, Adeka Glycyrrol ED-523T (all manufactured by ADEKA);

Examples of the aromatic epoxy compound include phenols having at least one aromatic ring such as phenol, cresol, and butylphenol, or a mono / polyglycidyl etherified product of an alkylene oxide adduct thereof; an epoxy compound having an aromatic heterocycle; and the like. Can be mentioned.
Typical compounds of these aromatic epoxy compounds include bisphenol A, bisphenol F, or glycidyl etherified compounds or epoxy novolac resins obtained by further adding alkylene oxide to these compounds;
Mono / polyglycidyl etherified compounds of aromatic compounds with two or more phenolic hydroxyl groups such as resorcinol, hydroquinone, catechol;
A glycidyl etherified product of an aromatic compound having two or more alcoholic hydroxyl groups such as phenyldimethanol, phenyldiethanol, and phenyldibutanol;
Glysidyl ester of a polybasic acid aromatic compound having two or more carboxylic acids such as phthalic acid, terephthalic acid and trimellitic acid, glycidyl ester of benzoic acid, styrene oxide or epoxidized product of divinylbenzene;
Epoxy compounds having a triazine skeleton such as 2,4,6-tri (glycidyloxy) -1,3,5-triazine; and the like.

A commercially available product can also be used as the aromatic epoxy compound. Commercially available products include Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, On-Coat EX-1020, On-Coat EX-1030, On-Coat EX. -1040, On-Coat EX-1050, On-Coat EX-1051, On-Coat EX-1010, On-Coat EX-1011, On-Coat 1012 (all manufactured by Nagase ChemteX);
Ogsol PG-100, Ogsol EG-200, Ogsol EG-210, Ogsol EG-250 (all manufactured by Osaka Gas Chemical Co., Ltd.);
HP4032, HP4032D, HP4700 (all manufactured by DIC Corporation);
ESN-475V (above, manufactured by Nippon Steel & Sumikin Co., Ltd.);
jER YX8800 (above, manufactured by Mitsubishi Chemical Corporation);
Maproof G-0105SA, Maproof G-0130SP (all manufactured by NOF CORPORATION);
Epicron N-665, Epicron HP-7200 (all manufactured by DIC Corporation);
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 Co., Ltd.);
Adeka Resin EP-4000, Adeka Resin EP-4005, Adeka Resin EP-4100, Adeka Resin EP-4901 (all manufactured by ADEKA);
TECHMORE VG-3101L (above, manufactured by Printec);
Examples thereof include TEPIC-FL, TEPIC-PAS, TEPIC-UC (all manufactured by Nissan Chemical Industries, Ltd.).

The alicyclic epoxy compound includes a polyglycidyl etherified product of a polyhydric alcohol having at least one alicyclic structure, or cyclohexene oxide or cyclopentene obtained by epoxidizing a cyclohexene or cyclopentene ring-containing compound with an oxidizing agent. Examples include oxide-containing compounds.
Typical compounds of these alicyclic epoxy compounds are hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 3,4-epoxy-1-methylcyclohexyl. -3,4-Epoxy-1-methylhexanecarboxylate, 6-Methyl-3,4-Epoxycyclohexylmethyl-6-methyl-3,4-Epoxycyclohexanecarboxylate, 3,4-Epoxy-3-methylcyclohexylmethyl -3,4-epoxy-3-methylcyclohexanecarboxylate, 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 (3,3) 4-epoxycyclohexyl) propane, dicyclopentadiene diepoxyside, dicyclopentadiene dimethanol diglycidyl ether, ethylenebis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2 epoxyhexahydrophthalate -Epoxyhexyl, 1-epoxyethyl-3,4-epoxycyclohexane, 1,2-epoxy-2-epoxyethylcyclohexane, α-pinenooxide, limonendioxide and the like can be mentioned.

A commercially available product can also be used as the alicyclic epoxy compound. Commercially available products include celoxide 2021P, celoxide 2081, celoxide 2000, celoxide 3000 (above, manufactured by Daicel); Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.); jER YX8000, jER YX8034 (above, manufactured by Mitsubishi Chemical Corporation); ADEKA REGIN EP- 4088S, Adeka Resin EP-4088L, Adeka Resin EP-4080E (all manufactured by ADEKA Corporation); and the like.

Further, as a compound having an oxylan group in the molecule, an epoxy compound having both an alicyclic structure and an aromatic ring in one molecule can be mentioned. Examples of such a compound include Epicron HP-7200 (manufactured by DIC Corporation).

Among these, an alicyclic epoxy resin is preferable as the compound having an oxylan group from the viewpoint of lowering the dielectric constant of the cured adhesive layer and easily forming the cured adhesive layer having excellent colorless transparency. Further, when the adhesive layer contains a cationic polymerization initiator, the alicyclic epoxy resin is preferable from the viewpoint of avoiding excessively slow progress of the cationic polymerization because the reactivity of the cationic polymerization is high.
When a thermal cationic polymerization initiator is used as the curing agent described later, the compound having an oxylan group is preferably a compound having a glycidyl ether group. Cationic polymerization reactions involving glycidyl ether groups tend to proceed relatively gently. Therefore, when the manufacturing process of the adhesive layer includes a step of heating the composition containing the components constituting the adhesive layer (for example, a step of heating to 90 ° C. or higher), the polymerization reaction of the glycidyl ether group is difficult to proceed. , It is easy to keep the storage elastic modulus of the adhesive layer low at 23 ° C. The content of the compound having a glycidyl ether group is preferably 70% by mass or more, and preferably 90% by mass or more, based on the whole compound having a cyclic ether group. Further, when the content of the compound having a glycidyl ether group is 90% by mass or more with respect to the entire compound having a cyclic ether group, the storage stability of the adhesive layer can be improved.

Compounds having an oxetane group in the molecule include 3,7-bis (3-oxetanyl) -5-oxa-nonane, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1, 2-Bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1,3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ) Ether, triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3-ethyl-3-oxetanylmethoxy) Bifunctional aliphatic oxetane compounds such as butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, 3-ethyl-3-[(phenoxy) methyl] oxetane, 3-ethyl-3- (hexyloxy) Monofunctional oxetane compounds such as methyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3- (hydroxymethyl) oxetane, 3-ethyl-3- (chloromethyl) oxetane, etc. Can be mentioned.

As the compound having an oxetane group in the molecule, a commercially available product can also be used. Commercially available products include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether (manufactured by Maruzen Petrochemical Co., Ltd.);
Aron Oxetane OXT-121, OXT-221, EXOH, POX, OXA, OXT-101, OXT-221, OXT-212 (all manufactured by Toagosei);
Etanacol OXBP, OXTP (above, manufactured by Ube Industries, Ltd.); and the like.

These cyclic ether compounds (A) can 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 thereof when two or more kinds of cyclic ether compounds (A) are contained) is preferably 53 to 80 mass by mass with respect to the entire adhesive layer. %, More preferably 57 to 75% by mass.
By keeping the content of the cyclic ether compound (A) within the above range, it becomes easy to obtain an adhesive cured product layer having a high storage elastic modulus at 90 ° C.

At least one of the cyclic ether compounds (A) in the adhesive layer is preferably a compound (cyclic ether compound (AL)) that is liquid at 25 ° C. Here, the liquid is one of the aggregated states of substances, which has a substantially constant volume but does not have a unique 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), it is possible to prevent the storage elastic modulus of the adhesive layer from becoming too high at 23 ° C. Therefore, it becomes easy to obtain an adhesive layer having sufficient adhesive strength at room temperature and excellent adhesiveness.

From the viewpoint of adjusting the storage elastic 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 thereof when two or more compounds are contained) is preferably 53% by mass or more, more preferably 57, based on the entire adhesive layer. It is mass% or more. When the content of the cyclic ether compound (AL) is 53% by mass or more with respect to the entire adhesive layer, it becomes easy to obtain an adhesive layer having sufficient adhesive strength at room temperature and excellent adhesiveness. In addition, a cured adhesive layer having a high storage elastic modulus at 90 ° C. can be easily obtained.

The content of the cyclic ether compound (AL) in the adhesive layer (the total amount thereof when two or more compounds are contained) is preferably 70% by mass or less, more preferably 68, based on the entire adhesive layer. It is less than mass%. When the content of the cyclic ether compound (AL) is 70% by mass or less with respect to the entire adhesive layer, it becomes easy to obtain an adhesive sheet for device encapsulation having excellent peelability of the release film.

(Binder resin)
The adhesive layer may contain a binder resin (B). The adhesive layer containing the binder resin (B) has excellent shape retention and handleability.

The weight average molecular weight (Mw) of the binder resin (B) is not particularly limited, but is preferably 10,000 or more, more preferably 10,000 or more because it is excellent in compatibility with the cyclic ether compound (A) and also excellent in shape retention. Is 10,000 to 150,000, more preferably 10,000 to 100,000.
The weight average molecular weight (Mw) of the binder resin (B) can be determined as a standard polystyrene-equivalent value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

When the adhesive layer contains the binder resin (B), the content of the binder resin (B) (when two or more kinds of binder resins (B) are contained, the total amount of these) is applied to the entire adhesive layer. , It is preferably 20 to 46% by mass, and more preferably 23 to 44% by mass.
When the content of the binder resin (B) is within the above range, it becomes easy to obtain an adhesive layer having excellent shape retention and sufficient adhesive strength.

As the binder resin (B), a resin having a glass transition temperature (Tg) of 60 ° C. or higher is preferable, a resin having a glass transition temperature (Tg) of 90 ° C. or higher is more preferable, and a resin having a glass transition temperature (Tg) of 110 ° C. or higher is further preferable. By glass transition temperature (Tg) used 60 ° C. or more resins, it is easy to storage modulus at 90 ° C. of the cured adhesive layer to more than 1 × 10 8 ^Pa.
Further, since the glass transition temperature (Tg) of the binder resin (B) is 90 ° C. or higher, the storage elastic modulus of the adhesive layer at 23 ° C. will be described later even when a large amount of the cyclic ether compound (AL) is contained. It is easy to set the range to .5 × 10 ⁵ Pa or more.
The glass transition temperature (Tg) of the binder resin (B) can be measured according to JIS K 7121 using a differential scanning calorimeter.

Examples of the binder resin (B) include phenoxy resin, polyimide resin, polyamide-imide resin, polyvinyl butyral resin, polycarbonate resin, acrylic resin, urethane resin, modified olefin resin and the like.
These resins can be used alone or in combination of two or more.

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

The phenoxy resin generally corresponds to a high molecular weight epoxy resin and has a degree of polymerization of about 100 or more.

The phenoxy resin preferably has a weight average molecular weight (Mw) of 10,000 to 150,000, and more preferably 10,000 to 100,000. The weight average molecular weight (Mw) of the phenoxy resin can be determined as a standard polystyrene-equivalent value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.
The phenoxy-based resin corresponding to such a high molecular weight epoxy resin has excellent heat-resistant deformability.
The epoxy equivalent of the phenoxy resin is preferably 5,000 or more, more preferably 7,000 or more. The epoxy equivalent of the phenoxy resin can be measured according to JIS K7236.

Examples of phenoxy resins include bisphenol A type, bisphenol F type, bisphenol S type phenoxy resin, bisphenol A type and bisphenol F type copolymer type phenoxy resin, distilled products thereof, naphthalene type phenoxy resin, novolac type phenoxy resin, and biphenyl type. Examples thereof include phenoxy resin and cyclopentadiene type phenoxy resin.
These phenoxy resins can be used alone or in combination of two or more.

The phenoxy resin can be obtained by a method of reacting a bifunctional phenol and epihalohydrin to a high molecular weight, or by a double addition reaction of a bifunctional epoxy resin and a bifunctional phenol.
For example, it can be obtained by reacting bifunctional phenols and epihalohydrin in the presence of an alkali metal hydroxide in an inert solvent at a temperature of 40 to 120 ° C. Further, the bifunctional epoxy resin and the bifunctional phenols are mixed with an amide solvent or an ether solvent having a boiling point of 120 ° C. or higher in the presence of a catalyst such as an alkali metal compound, an organic phosphorus compound or a cyclic amine compound. It can also be obtained by performing a heavy addition reaction by heating to 50 to 200 ° C. with a reaction solid content concentration of 50% by weight or less in an organic solvent such as a ketone solvent, a lactone solvent, or an alcohol solvent.

The bifunctional phenols are not particularly limited as long as they are compounds having two phenolic hydroxyl groups. For example, monocyclic bifunctional phenols such as hydroquinone, 2-bromohydroquinone, resorcinol, 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) ethers; and linear alkyl groups, branched alkyl groups, aryl groups, methylol groups, allyl groups, cyclic aliphatic groups, halogens (aryl groups) on the aromatic rings of these phenol skeletons. Tetrabromobisphenol A, etc.), nitro group, etc. introduced; linear alkyl group, branched alkyl group, allyl group, allyl group with substituent, cyclic aliphatic group in the carbon atom in the center of these bisphenol skeletons Polycyclic bifunctional phenols into which a group, an alkoxycarbonyl group, etc. have been introduced; and the like can be mentioned.

Examples of epichlorohydrin include epichlorohydrin, epibrom hydrin, and epiiodohydrin.

Further, in the present invention, a commercially available product can also be used as the phenoxy resin. For example, trade names manufactured by Mitsubishi Chemical Co., Ltd .: YX7200 (glass transition temperature: 150 ° C.), YX6954 (bisphenol acetophenone skeleton-containing phenoxy resin, glass transition temperature: 130 ° C.), YL7553, YL6794, YL7213, YL7290, YL7482, YX8100 (bisphenol). S skeleton-containing phenoxy resin), Toto Kasei Co., Ltd. trade names: FX280, FX293, FX293S (fluorene skeleton-containing phenoxy resin), Mitsubishi Chemical Co., Ltd. trade names: jER1256, jER4250 (glass transition temperature: less than 85 ° C), jER4275 (Glass transition temperature: 75 ° C), trade name manufactured by Nittetsu Chemical & Materials Co., Ltd .: YP-50 (glass transition temperature: 84 ° C), YP-50S (all bisphenol A skeleton-containing phenoxy resin), YP-70 ( Examples thereof include bisphenol A skeleton / bisphenol F skeleton copolymer phenoxy resin, glass transition temperature: less than 85 ° C., ZX-1356-2 (glass transition temperature: 72 ° C.), and the like. For those for which the glass transition temperature is known, the glass transition temperature is shown.

The modified olefin resin is an olefin resin having a functional group introduced, which is obtained by subjecting an olefin resin as a precursor to a modification treatment using a modifier.

The olefin resin refers to a polymer containing a repeating unit derived from an olefin monomer. The olefin-based resin may be a polymer consisting of only repeating units derived from the olefin-based monomer, or the repeating units derived from the olefin-based monomer and a monomer copolymerizable with the olefin-based monomer. It may be a polymer composed of a repeating unit of origin.

As the olefin-based monomer, α-olefin having 2 to 8 carbon atoms is preferable, ethylene, propylene, 1-butene, isobutylene, or 1-hexene is more preferable, and ethylene or propylene is further preferable. These olefin-based monomers may be used alone or in combination of two or more.
Examples of the monomer copolymerizable with the olefin-based monomer include vinyl acetate, (meth) acrylic acid ester, and styrene. Here, "(meth) acrylic acid" means acrylic acid or methacrylic acid (the same shall apply hereinafter).
As the monomer copolymerizable with these olefin-based monomers, one type can be used alone, or two or more types can be used in combination.

Examples of the olefin resin include ultra-low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), and ethylene-propylene. Examples thereof include copolymers, olefin-based elastomers (TPO), ethylene-vinyl acetate copolymers (EVA), ethylene- (meth) acrylic acid copolymers, and ethylene- (meth) acrylic acid ester copolymers.

The modifier used for the modification treatment of the olefin resin is a compound having a functional group in the molecule.
Functional groups include carboxyl group, carboxylic acid anhydride group, carboxylic acid ester group, hydroxyl group, epoxy group, amide group, ammonium group, nitrile group, amino group, imide group, isocyanate group, acetyl group, thiol group and ether group. , Thioether group, sulfone group, phosphone group, nitro group, urethane group, alkoxysilyl group, silanol group, halogen atom and the like. The compound having a functional group may have two or more kinds of functional groups in the molecule.

The weight average molecular weight (Mw) of the modified olefin resin is preferably 10,000 to 150,000, more preferably 30,000 to 100,000.
The weight average molecular weight (Mw) of the modified olefin resin can be determined as a standard polystyrene-equivalent value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

As the modified olefin resin, an acid modified olefin resin is preferable. The acid-modified olefin-based resin refers to an olefin-based resin graft-modified with an acid or an acid anhydride. For example, an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride (hereinafter, may be referred to as "unsaturated carboxylic acid") is reacted with an olefin resin to introduce a carboxyl group or a carboxylic acid anhydride group (graft). Denatured).

Examples of unsaturated carboxylic acids that react with olefinic resins include unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid; Unsaturated carboxylic acid anhydrides such as glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic acid anhydride, and tetrahydrophthalic acid anhydride;
These can be used individually by 1 type or in combination of 2 or more types. Among these, maleic anhydride is preferable because it is easy to obtain a sealing material having higher adhesive strength.

The amount of unsaturated carboxylic acid or the like to be reacted with the olefin resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and further preferably 0 with respect to 100 parts by mass of the olefin resin. .2 to 1 part by mass. By curing the adhesive layer containing the acid-modified olefin resin thus obtained, a sealing material having higher adhesive strength can be formed.

The method for introducing the unsaturated carboxylic acid unit or the unsaturated carboxylic acid anhydride unit into the olefin resin is not particularly limited. For example, a method in which an olefin resin and an unsaturated carboxylic acid are heated and melted above the melting point of the olefin resin to react in the presence of a radical generator such as an organic peroxide or an azonitrile, or an olefin. After dissolving the system resin and unsaturated carboxylic acid or the like in an organic solvent, the unsaturated carboxylic acid or the like is graft-copolymerized with the olefin resin by a method of heating, stirring and reacting in the presence of a radical generator. The method can be mentioned.

A commercially available product can also be used as the acid-modified olefin resin. Examples of commercially available products include Admer (registered trademark) (Mitsui Chemicals), Unistor (registered trademark) (Mitsui Chemicals), BondyRam (Polyram), orevac (registered trademark) (ARKEMA), and the like. Modic (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and the like can be mentioned.

[Curing agent]
The adhesive layer may contain a curing agent. When the adhesive layer contains a curing agent, the curability of the adhesive layer is further enhanced.
The curing agent is not particularly limited as long as it initiates the curing reaction, but from the viewpoint that it may be difficult or should be avoided to cure the adhesive layer with energy rays such as ultraviolet rays. From the viewpoint that it is not necessary to introduce an energy ray irradiation device, a device that starts the curing reaction by heating is preferably used.
Examples of the curing agent include a thermal cationic polymerization initiator and other curing agents.
Examples of the curing agent other than the thermal cationic polymerization initiator include tertiary amines such as benzylmethylamine and 2,4,6-trisdimethylaminomethylphenol; 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-hepta. Examples thereof include imidazole compounds such as decylimidazole; Lewis acids such as boron trifluoride / monoethylamine complex and boron trifluoride / piperazine complex;

As the curing agent, one type can be used alone, or two or more types can be used in combination.
When the adhesive layer contains a curing agent, the content of the curing agent is not particularly limited, but is preferably 0.1 to 15 parts by mass, more preferably 1 to 1 to 100 parts by mass with respect to 100 parts by mass of the cyclic ether compound (A). It is 10 parts by mass, more preferably 1 to 5 parts by mass.

The adhesive layer preferably contains a thermal cationic polymerization initiator as at least one of the curing agents.
By using the thermal cationic polymerization initiator, the curability of the adhesive layer can be controlled more accurately.

The thermal cationic polymerization initiator is a compound capable of generating a cationic species that initiates polymerization by heating.
Examples of the thermal cationic polymerization initiator include sulnifoam salt, quaternary ammonium salt, phosphonium salt, diazonium salt, iodonium salt and the like.

Examples of the sulfonium salt include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroalcinate, tris (4-methoxyphenyl) sulfonium hexafluoroalcinate, and diphenyl (4-phenylthiophenyl) sulfonium. Hexafluoroalcinate, (4-acetoxyphenyl) methyl (2-methylbenzyl) sulfonium tetrakis (pentafluorophenyl) borate, (4-hydroxyphenyl) methyl (4-methylbenzyl) sulfonium tetrakis (pentafluorophenyl) borate, ( Examples thereof include 4-acetoxyphenyl) benzyl (methyl) sulfonium tetrakis (pentafluorophenyl) borate, benzyl (4-hydroxyphenyl) (methyl) sulfonium tetrakis (pentafluorophenyl) borate and the like.

A commercially available product can also be used as the sulfonium salt. Commercially available products include Adeca Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, Adeka Opton CP-77 (all manufactured by Asahi Denka Co., Ltd.), Sun Aid SI-60L, Sun Aid SI-80L, Sun Aid SI-100L, Sun Aid SI. -B2A, Sun Aid SI-B7, Sun Aid SI-B3A, Sun Aid SI-B3 (above, manufactured by Sanshin Chemical Co., Ltd.), CYRACURE UVI-6974, CYRACURE UVI-6990 (above, manufactured by Union Carbide), UVI-508, UVI-509 (above, General Electric), FC-508, FC-509 (above, Minnesota Mining and Manufacturing), CD-1010, CD-1011 (above, Thirstmer), Examples include CI series products (manufactured by Nippon Soda Co., Ltd.).

Examples of the quaternary ammonium salt include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydrogen sulfate, tetraethylammonium tetrafluoroborate, tetraethylammonium p-toluenesulfonate, N, N-dimethyl-N-. Benzylanilinium Hexafluoroammonate, N, N-dimethyl-N-benzylanilinium tetrafluoroborate, N, N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N, N-diethyl-N-benzyltrifluoromethanesulfonate , N, N-Dimethyl-N- (4-methoxybenzyl) pyridinium hexafluoroammonate, N, N-diethyl-N- (4-methoxybenzyl) toluidinium hexafluoroammonate and the like.

Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

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

Examples of the iodonium salt include diphenyl iodonium hexafluoroalcinate, bis (4-chlorophenyl) iodonium hexafluoroalcinate, bis (4-bromophenyl) iodonium hexafluoroalcinate, and phenyl (4-methoxyphenyl) iodonium hexafluoroalcinate. Can be mentioned. In addition, as commercial products, UV-9310C (manufactured by Toshiba Silicone), Photoinitiator 2074 (manufactured by Rhone-Poulenc), UVE series products (manufactured by General Electric), FC series products (Minnesota Mining and Manufacturing) (Manufactured by the company) can also be used.

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

In the adhesive sheet for device encapsulation of the present invention, it is preferable that all of the curing agents contained in the adhesive layer are thermal cationic polymerization initiators.
If a curing agent other than the thermal cationic polymerization initiator is used, the adhesive layer may be colored or the transparency of the adhesive layer may be lowered.
On the other hand, when a thermal cationic polymerization initiator is used, such a problem is unlikely to occur. Therefore, since all the curing agents contained in the adhesive layer are thermal cationic polymerization initiators, an adhesive layer having excellent colorless transparency can be obtained. It can be formed efficiently.

(Silane coupling agent)
The adhesive layer may contain a silane coupling agent. By curing the adhesive layer containing the silane coupling agent, it is possible to form a sealing material having better moist heat durability.

As the silane coupling agent, a known silane coupling agent can be used. Of these, an organosilicon compound having at least one alkoxysilyl group in the molecule is preferable.

Examples of the silane coupling agent include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltri. A silane coupling agent having a (meth) acryloyl group such as methoxysilane and 8-methacryloxyoctyltrimethoxysilane;
A silane coupling agent having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, trichlorovinylsilane, vinyltris (2-methoxyethoxy) silane, and 7-octenyltrimethoxysilane;
2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 8-glycid A silane coupling agent having an epoxy group such as xioctyltrimethoxysilane;
Silane coupling agent having a styryl group 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, N-phenyl-3-aminopropyltrimethoxysilane, N -A silane coupling agent having an amino group such as hydrochloride of (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -8-aminooctyltrimethoxysilane;
Silane coupling agent having a ureido group such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane;
Silane coupling agent having halogen atoms such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane;
Silane coupling agent having a mercapto group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane;
Silane coupling agent having a sulfide group such as bis (trimethoxysilylpropyl) tetrasulfide and bis (triethoxysilylpropyl) tetrasulfide;
Silane coupling agent having an isocyanate group such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane;
A silane coupling agent having an allyl group such as allyltrichlorosilane, allyltriethoxysilane, and allyltrimethoxysilane;
Examples thereof include a silane coupling agent having a hydroxyl group such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane; and the like.
Among these, from the viewpoint of improving the adhesiveness of the adhesive layer to the adherend, it is preferable to use a long-chain spacer type silane coupling agent having a linear alkyl group having 6 or more carbon atoms. Examples of the long-chain spacer-type silane coupling agent having a linear alkyl group having 6 or more carbon atoms include 8-methacryloxyoctyltrimethoxysilane, 7-octenyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, and N. -(2-Aminoethyl) -8-aminooctyltrimethoxysilane and the like can be mentioned, and 8-glycidoxyoctyltrimethoxysilane is preferably used.
These silane coupling agents may be used alone or in combination of two or more.

When the adhesive layer contains a silane coupling agent, the content of the silane coupling agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass in the entire adhesive layer. ..

(Other ingredients)
The adhesive layer may contain other components as long as the effects of the present invention are not impaired.
Examples of other components include additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, bulking agents, softeners, and tackifiers.
These can be used alone or in combination of two or more.
When the adhesive layer contains these additives, the content thereof can be appropriately determined according to the purpose.

(Adhesive layer)
The shape, size, etc. of the adhesive layer are not particularly limited. Further, it may be a strip-shaped one or a long one. In the present specification, the "long shape" means a shape having a length of 5 times or more with respect to the width, preferably having a length of 10 times or more, and specifically being wound in a roll shape. The shape of a film that is long enough to be taken, stored, or transported. The upper limit of the ratio of the length to the width of the film is not particularly limited, but may be, for example, 100,000 times or less.

The thickness of the adhesive layer is usually 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 suitably used as a material for forming a sealing material.
The thickness of the adhesive layer can be measured according to JIS K 7130 (1999) using a known thickness meter.

The adhesive layer may have a single-layer structure or may have a multi-layer structure (a plurality of adhesive layers are laminated).
The adhesive layer may have a uniform component or a non-uniform component (for example, in the above-mentioned adhesive layer having a multi-layer structure, both components are mixed at the interface between the two adhesive layers. , It may have a single-layer structure in appearance).

The storage elastic modulus of the adhesive layer at 23 ° C. is 9.5 × 10 ⁵ Pa or more and 3.0 × 10 ⁷ Pa or less, preferably 9.9 × 10 ⁵ Pa or more and 2.0 × 10 ⁷ Pa or less. is there. Further, since it is possible to reduce the pressure applied at the time of sticking the adhesive layer to be sealed was storage modulus at 23 ° C. of the adhesive layer is preferably not more than 1.3 × 10 7 ^Pa, more preferably Is 1.1 × 10 ⁷ Pa or less, more preferably 1.0 × 10 ⁷ Pa or less.

Since the storage elastic modulus of the adhesive layer at 23 ° C. is 9.5 × 10 ⁵ Pa or more, when the adhesive sheet for device encapsulation is cut into a predetermined shape, the adhesive layer is punched without being significantly deformed. The blade can be pushed into the device sealing adhesive sheet. Therefore, it is possible to prevent the adhesive from adhering to the portion of the release film that has not been peeled off, and the release film can be efficiently peeled off.
An adhesive layer having a storage elastic modulus of 9.5 × 10 ⁵ Pa or more at 23 ° C. can be easily obtained by using, for example, a cyclic ether compound (A) having a large cyclic ether equivalent. Further, by reducing the content of the cyclic ether compound (AL) in the adhesive layer, the storage elastic modulus of the adhesive layer at 23 ° C. can be reduced. Further, by using a relatively rigid resin such as a phenoxy resin, the storage elastic modulus at 23 ° C. is 9. even when the content of the cyclic ether compound (AL) in the adhesive layer is large. It is easy to obtain an adhesive layer of 5 × 10 ⁵ Pa or more.

By storage modulus at 23 ° C. of the adhesive layer is not more than 3.0 × 10 7 ^Pa, the adhesive layer has sufficient adhesive strength at normal temperature, and is excellent in sticking resistance.
Storage modulus at 23 ° C. is 3.0 × 10 7 ^Pa or less of the adhesive layer, for example, easily obtained by increasing the amount of cyclic ether compound (AL). Further, as described above, when the adhesive layer contains a thermal cationic polymerization initiator, the cyclic ether compound (A) is a compound having a glycidyl ether group, so that the adhesive layer is stored at 23 ° C. lowering the elastic modulus, easily than 3.0 × ¹⁰ 7 Pa.
The storage elastic modulus of the adhesive layer can be measured using a known dynamic viscoelasticity measuring device.
Specifically, it can be measured by the method described in Examples.

The adhesive layer is curable. That is, by performing a predetermined curing treatment on the adhesive layer, the cyclic ether groups in the cyclic ether compound (A) react, and the adhesive layer is cured to become an adhesive cured product layer.
Examples of the curing treatment include heat treatment and light irradiation treatment. These can be appropriately determined according to the properties of the adhesive layer.

The storage elastic modulus of the cured adhesive layer at 90 ° C. is preferably 1 × 10 ⁸ Pa or more, and more preferably 1 × 10 ⁹ to 1 × 10 ¹¹ Pa. An adhesive cured product layer having a storage elastic modulus of 1 × 10 ⁸ Pa or more at 90 ° C. is more suitable as a sealing material because it has excellent sealing properties. Further, in the step performed for manufacturing the device encapsulant after the adhesive cured product layer is formed, the adhesive cured product layer is easily prevented from being broken or peeled off.
The storage elastic modulus of the cured adhesive layer can be measured using a known dynamic viscoelasticity measuring device.
Specifically, it can be measured by the method described in Examples.

The adhesive cured product layer has excellent adhesive strength. The adhesive strength of the cured adhesive layer is usually 1 to 20 N / 25 mm, preferably 2.5 to 15 N / 25 mm when a 180 ° peeling test is performed under the conditions of a temperature of 23 ° C. and a relative humidity of 50%. .. This 180 ° peeling test can be performed, for example, under the conditions of a temperature of 23 ° C. and a relative humidity of 50% according to the method for measuring the adhesive strength described in JIS Z0237: 2009.

When the adhesive sheet for device encapsulation of the present invention is used to form an encapsulant in an optical device such as a light emitting device, a light receiving device, or a display device, the adhesive cured product layer is excellent in colorless transparency. Is preferable. The total light transmittance of the cured adhesive layer having a thickness of 15 μm is preferably 85% or more, more preferably 90% or more. There is no particular upper limit to 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 cured adhesive 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.

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

The release film functions as a support in the manufacturing process of the adhesive sheet for device encapsulation, and also functions as a protective sheet for the adhesive layer until the adhesive sheet for device encapsulation is used.

As the release film, a conventionally known one can be used. For example, those having a release layer on a substrate for a release film can be mentioned. The release layer can be formed by using a known release agent.

As the base material for the release film, paper base materials such as glassin paper, coated paper, and high-quality paper; laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials; polyethylene terephthalate resin, polybutylene terephthalate resin, etc. Plastic films such as polyethylene naphthalate resin, polypropylene resin, and polyethylene resin; and the like.
Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.
The thickness of the release film is not particularly limited, but is usually about 20 to 250 μm.

[Adhesive sheet for device encapsulation]
The adhesive sheet for sealing a device of the present invention has the first release film and the second release film, and the adhesive layer sandwiched between the release films.
Examples of the adhesive sheet for sealing the device of the present invention include a three-layer structure of a first release film / adhesive layer / second release film.

The method for manufacturing the adhesive sheet for device encapsulation of the present invention is not particularly limited. For example, a casting method can be used to produce an adhesive sheet for device encapsulation.

When the adhesive sheet for device encapsulation is manufactured by the casting method, for example, it can be manufactured by the following method.
Two release films having a release layer (release film (A) and release film (B)) and a coating liquid containing components constituting the adhesive layer are prepared. An adhesive layer is formed by applying a coating liquid to the release layer surface of the release film (A) using a known method and drying the obtained coating film. Next, the adhesive sheet for device encapsulation can be obtained by stacking the release film (B) on the adhesive layer so that the release layer surface of the release film (B) is in contact with the adhesive layer.

When the coating liquid is prepared by diluting the components constituting the adhesive layer, the solvent used for preparing the coating liquid is an aromatic hydrocarbon solvent such as benzene or toluene; an ester such as ethyl acetate or butyl acetate. System solvent; Ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone; aliphatic hydrocarbon solvent such as n-pentane, n-hexane, n-heptane; alicyclic hydrocarbon such as cyclopentane, cyclohexane, methylcyclohexane System solvent; and the like.
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 coatability and the like.

Examples of the method of applying the coating liquid include 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, and a gravure coating method.

Examples of the method of volatilizing the solvent in the coating film to dry the coating film include conventionally known drying methods such as hot air drying, hot roll drying, and infrared irradiation.
The conditions for drying the coating film are, for example, 80 to 150 ° C. for 30 seconds to 5 minutes, and more preferably 90 to 120 ° C. for 1 minute to 4 minutes. By drying the coating film at 90 ° C. or higher, it is easy to dry the coating film even with a drying time of 5 minutes or less, and the productivity is excellent.

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

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

Step (b1): The second release film of the device sealing adhesive sheet is peeled off to obtain an intermediate for device sealing.
Step (b2): The adhesive layer exposed by performing the step (b1) is attached to a substrate (glass plate, gas barrier film, etc.).
Step (b3): The first release film is further peeled off from the device sealing intermediate.
Step (b4): The adhesive layer exposed by performing the step (b3) is attached to the object to be sealed (device).
Step (b5): The adhesive layer is cured by a predetermined means to form an adhesive cured product layer.

In the above method for manufacturing a device encapsulant, in the step (a2) or the step (b2), the adhesive layer is attached to the object to be sealed or the substrate at room temperature from the viewpoint of convenience of work and productivity. It is preferable to carry out in an environment (15 to 35 ° C., the same below). Similarly, the step (b4) is preferably performed in a room temperature environment.

In the device sealing adhesive sheet of the present invention, the punching blade can be pushed into the device sealing adhesive sheet without significantly deforming the adhesive layer when cutting into a predetermined shape. Therefore, it is possible to prevent the adhesive from adhering to the portion of the release film that has not been peeled off, and the release film can be efficiently peeled off.
Further, the cured adhesive layer formed by using the adhesive layer constituting the adhesive sheet for sealing the device of the present invention is excellent in adhesive strength and water vapor blocking property. Therefore, the adhesive sheet for device encapsulation of the present invention is suitably used as a material for forming a sealing material in a device encapsulant.

The device encapsulant is not particularly limited. Examples of the device sealant include light-related devices such as a light emitting device, a light receiving device, and a display device. When the adhesive layer has high translucency, the adhesive sheet for device encapsulation of the present invention is preferably used as a material for forming a sealing material in an optical device encapsulant. Specific examples of these include 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;

When the adhesive cured product layer obtained from 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 an organic EL display, an organic EL lighting, or the like. It is suitably used as a material for forming a sealing material in devices such as liquid crystal displays and electronic papers.

Hereinafter, the present invention will be described in more detail with reference to examples. 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 Co., Ltd., trade name: YX8000, liquid at 25 ° C., epoxy equivalent: 205 g / eq)
-Cyclic ether compound (AL2): Hydrogenated bisphenol A type glycidyl ether epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., trade name: YX8034, liquid at 25 ° C., epoxy equivalent: 270 g / eq)
Binder resin (B1): (Phenoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX7200B35, glass transition temperature (Tg): 150 ° C.)
-Curing agent (C1): Thermal cationic polymerization initiator: Benzyl (4-hydroxyphenyl) (methyl) Sulfonium tetrakis (pentafluorophenyl) borate (manufactured by Sanshin Chemical Co., Ltd., trade name: Sun Aid SI-B3)
-Curing agent (C2): Imidazole-based curing agent (manufactured by Shikoku Chemicals Corporation, trade name: Curesol 2E4MZ)
-Silane coupling agent (D1): 8-glycidoxyoctyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM4803)
-Release film (E1): manufactured by Lintec Corporation, trade name: SP-PET752150
-Release film (E2): manufactured by Lintec Corporation, trade name: SP-PET381130

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

[Example 2, Comparative Examples 1 and 2]
An adhesive sheet for device encapsulation was obtained in the same manner as in Example 1 except that the types and amounts of the components constituting the adhesive layer were changed to those shown in Table 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 Elastic Modulus of Adhesive Layer The adhesive layer of the adhesive sheet for device encapsulation obtained in Example or Comparative Example was laminated at 23 ° C. to a thickness of about 1 mm using a laminator, and obtained. The storage elastic modulus was measured using the laminate as a measurement sample.
That is, for this measurement sample, a storage elastic modulus measuring device (manufactured by Antonio Par, trade name: Physica MCR301) was used under the conditions of a frequency of 1 Hz, a strain of 1%, and a temperature rise rate of 3 ° C./min. The storage elastic modulus in the temperature range of + 150 ° C. was measured. The measurement results at 23 ° C. are shown in Table 1.

(2) Storage Elastic Modulus of Cured Adhesive Layer The adhesive layer of the adhesive sheet for device encapsulation obtained in Example or Comparative Example was laminated at 23 ° C. to a thickness of 200 μm using a laminator, and obtained. The laminated body was heated at 110 ° C. for 1 hour to obtain a cured product thereof. This cured product was used as a measurement sample, and its storage elastic modulus was measured.
That is, for this measurement sample, a storage elastic modulus measuring device (manufactured by TA Instruments, trade name: DMAQ800) was used, and the temperature was -20 ° C. The storage elastic modulus in the temperature range of ~ + 150 ° C. was measured. The measurement results at 90 ° C. are shown in Table 1.

(3) Evaluation of Adhesive Layer Adhesive Adhesiveness to Enclosed Material The device-sealing adhesive sheet obtained in Examples and Comparative Examples was cut to obtain a test piece having a width of 50 mm and a length of 150 mm. The adhesive layer exposed by peeling off the second release film of the obtained test piece was laminated on non-alkali glass under the conditions of a temperature of 23 ° C. and a relative humidity of 50%, and further, using a pressure-bonding roll, 0.5 MPa. Pressure was applied. The state of floating of the adhesive layer from the non-alkali glass was observed, and the one without floating was evaluated as A, and the one with floating was evaluated as B.

(4) Evaluation of Cutability of Adhesive Sheet for Device Encapsulation The adhesive sheet for device encapsulation obtained in Examples and Comparative Examples was cut to a size of 150 mm in length and 165 mm in width by using an air-type sample cutting device.
Specifically, the adhesive sheet for device encapsulation was cut by pushing a punching blade of the above size from the second release film side of the adhesive sheet for device encapsulation to obtain a test piece.
The second release film of the obtained test piece was peeled off. At this time, if the adhesive layer is not peeled off from the first release film, the adhesive layer adheres to the edge of the second release film, and the adhesive layer peels off from the first release film. Was evaluated as B.

The following can be seen from Table 1.
The adhesive layer of the device sealing adhesive sheet obtained in Examples 1 and 2 has excellent adhesiveness at 23 ° C.
Further, these adhesive sheets for sealing the device are also excellent in cutting processability, and the release film can be efficiently peeled off and removed.
On the other hand, the adhesive layer of the adhesive sheet for device encapsulation obtained in Comparative Example 1 has excellent adhesiveness at 23 ° C, but the storage elastic modulus of the adhesive layer at 23 ° C is too low, so that the device is sealed. The adhesive sheet for stopping is inferior in cutting workability.
Further, the adhesive layer of the adhesive sheet for device encapsulation obtained in Comparative Example 2 is inferior in stickability because the storage elastic modulus at 23 ° C. is too high.

Claims (11)

1. An adhesive sheet for device encapsulation having 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 following requirements (I) and requirements (I) Adhesive sheet for device encapsulation that satisfies II).
   Requirement (I): The adhesive layer is a layer containing one or more compounds having a cyclic ether group.
   Requirement (II): The storage elastic modulus of the adhesive layer at 23 ° C. is 9.5 × 10 ⁵ Pa or more and 3.0 × 10 ⁷ Pa or less.
2. The adhesive sheet for device encapsulation according to claim 1, wherein at least one of the compounds having a cyclic ether group is a compound that is liquid at 25 ° C.
3. The adhesive sheet for device encapsulation according to claim 2, wherein the content of the compound having a cyclic ether group, which is liquid at 25 ° C., is 53% by mass or more with respect to the entire adhesive layer.
4. The adhesive sheet for device encapsulation according to claim 2 or 3, wherein the content of the compound having a cyclic ether group, which is liquid at 25 ° C., is 65% by mass or less with respect to the entire adhesive layer.
5. The adhesive sheet for device encapsulation according to any one of claims 1 to 4, wherein the adhesive layer further contains a curing agent, and at least one of the curing agents is a thermal cationic polymerization initiator.
6. The adhesive sheet for device encapsulation according to claim 5, wherein all of the curing agents are thermal cationic polymerization initiators.
7. The adhesive sheet for device encapsulation according to claim 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 encapsulation according to any one of claims 5 to 7, wherein at least one of the compounds having a cyclic ether group is an alicyclic epoxy resin.
9. The invention according to any one of claims 1 to 8, wherein the adhesive layer contains a binder resin, and at least one of the binder resins is a binder resin having a glass transition temperature (Tg) of 60 ° C. or higher. Adhesive sheet for device encapsulation.
10. The adhesive sheet for device encapsulation according to any one of claims 1 to 9, wherein the layer obtained by curing the adhesive layer has a storage elastic modulus at 90 ° C. of 1 × 10 ⁸ Pa or more.
11. The device sealing adhesive sheet according to any one of claims 1 to 10, which is used for forming a sealing material in an optical device.