JP7138101B2 - Adhesive sheet and sealing body - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive sheet having an adhesive layer with excellent sealing properties, and a sealed body obtained by sealing an object to be sealed with the adhesive sheet.

In recent years, organic EL elements have attracted attention as light-emitting elements capable of high-luminance light emission by low-voltage direct-current driving.
However, the organic EL element has a problem that the luminescence characteristics such as luminance, luminous efficiency, and luminous uniformity tend to deteriorate over time.
As a cause of the problem of deterioration of the luminescence characteristics, it has been considered that oxygen, moisture, etc. enter the inside of the organic EL element and deteriorate the electrodes and the organic layer. Therefore, in order to solve this problem, it has been proposed to use a pressure-sensitive adhesive sheet having excellent moisture barrier properties as a sealing material.

In addition, when manufacturing a display device such as a liquid crystal display (LCD) or a touch panel, an adhesive sheet is used for the purpose of bonding optical members. There is a demand for a pressure-sensitive adhesive sheet that is excellent in

As a pressure-sensitive adhesive sheet having such properties, Patent Document 1 proposes a pressure-sensitive adhesive sheet having specific adhesive properties and the like and having a rubber-based resin as a main component.
In this document, the adhesive sheet is an adhesive sheet with a low water vapor permeability, has sufficient adhesive strength even after the passage of moist heat, and is suppressed from yellowing after the passage of wet heat, It is described that the pressure-sensitive adhesive sheet preferably contains a silane coupling agent in addition to the rubber-based resin, because these characteristics are easily exhibited.

JP 2016-53157 A

As described in Patent Document 1, the use of a pressure-sensitive adhesive composition containing a rubber-based resin as a main component tends to yield a pressure-sensitive adhesive sheet with excellent moisture barrier properties.
However, according to the investigations of the present inventors, even such a pressure-sensitive adhesive composition may lose its adhesive strength after being placed under high humidity conditions, and it can be used as a material for forming a sealing material. It turns out there are some things you can't do.
Therefore, there has been a demand for a sealant-forming material that has excellent sealability and maintains its performance even after being placed under high humidity conditions.

The present invention has been made in view of the above circumstances, and provides an adhesive sheet having an adhesive layer with excellent sealing properties, and a sealing body in which an object to be sealed is sealed with the adhesive sheet. With the goal.

In order to solve the above problems, the present inventors have diligently studied the adhesive layer.
As a result, a thermosetting adhesive layer containing a specific proportion of a polyfunctional epoxy compound and having specific shear properties has excellent sealing properties and can However, the inventors have found that the performance is maintained, and have completed the present invention.

Thus, according to the present invention, the following adhesive sheets (1) to (10) and sealing bodies (11) and (12) are provided.
(1) An adhesive sheet having a thermosetting adhesive layer containing a polyfunctional epoxy compound, wherein the content of the polyfunctional epoxy compound is 5 to 50% by mass in the entire adhesive layer, and the following conditions are satisfied: An adhesive sheet that satisfies the following requirements [1] to [3] when subjected to a shear test (A) at .
[Shear test (A)]
Two rectangular non-alkaline glass sheets with a short side of 10 mm were prepared, and on one of these non-alkali glass sheets, a square adhesive layer with a side of 10 mm was applied to a bonding area of 100 mm ² (10 mm × 10 mm). and laminated under the conditions of a temperature of 60° C., a pressure of 0.2 MPa, and a lamination speed of 0.2 m/min. Next, another sheet of alkali-free glass was placed on the surface of the adhesive layer not in contact with the alkali-free glass so that the adhesion area was 100 mm ² (10 mm × 10 mm). A laminate is obtained by lamination under conditions of a pressure of 0.2 MPa and a lamination speed of 0.2 m/min. The laminate is then heated at 100° C. for 2 hours to cure the adhesive layer. Thereafter, the laminate is allowed to stand under the conditions of 23° C. and 50% relative humidity for 24 hours to obtain a measurement sample. Using the obtained measurement sample, the shear load is measured under the condition of a shear rate of 0.1 mm/min.
[Requirements]
Requirement [1]: Measured when the maximum shear load (P ¹ _max ) is less than 10,000% shear strain.
Requirement [2]: The value of the maximum shear load (P ¹ _max ) is 100N or more.
Requirement [3]: The shear load (P ¹ _10000% ) value at a shear strain of 10,000% is 50% or more of the maximum shear load (P ¹ _max ) value.
(2) The adhesive sheet according to (1), which satisfies the following requirements [4] when subjected to a shear test (B) under the following conditions.
[Shear test (B)]
A measurement sample is prepared in the same manner as in the shear test (A).
The obtained measurement sample was allowed to stand under conditions of a temperature of 60° C. and a relative humidity of 90% for 100 hours, and then under conditions of a temperature of 23° C. and a relative humidity of 50% for 24 hours. , the shear load is measured under the conditions of a shear rate of 0.1 mm/min.
[Requirements]
Requirement [4]: The value of the maximum shear load (P ² _max ) in the shear test (B) is 70% or more of the value of the maximum shear load (P ¹ _max ) in the shear test (1).
(3) The adhesive sheet according to (1) or (2), wherein the adhesive layer further contains a modified polyolefin resin.
(4) The adhesive sheet according to (3), wherein the content of the modified polyolefin resin is 40 to 90% by mass in the entire adhesive layer.
(5) The adhesive sheet according to any one of (1) to (4), wherein the adhesive layer further contains an imidazole curing catalyst.
(6) The adhesive sheet according to (5), wherein the content of the imidazole-based curing catalyst is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyfunctional epoxy compound contained in the adhesive layer.
(7) The adhesive sheet according to any one of (1) to (6), wherein the adhesive layer further contains a silane coupling agent.
(8) The adhesive sheet according to (7), wherein the content of the silane coupling agent is 0.01 to 2% by mass in the entire adhesive layer.
(9) The adhesive sheet according to any one of (1) to (8), wherein the adhesive layer has a thickness of 1 to 25 μm.
(10) The adhesive sheet according to any one of (1) to (9), further comprising a release film.
(11) A sealed body in which an object to be sealed is sealed using the adhesive sheet according to any one of (1) to (10).
(12) The sealing body according to (11), wherein the object to be sealed is an organic EL element, an organic EL display element, a liquid crystal display element, or a solar cell element.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet which has an adhesive bond layer which is excellent in sealing property, and the sealing body by which the to-be-sealed object is sealed with the said adhesive sheet are provided.

Hereinafter, the present invention will be described in detail by dividing into 1) an adhesive sheet and 2) a sealing body.

1) Adhesive sheet The adhesive sheet of the present invention is an adhesive sheet having a thermosetting adhesive layer containing a polyfunctional epoxy compound, wherein the content of the polyfunctional epoxy compound is 5 to 50 in the entire adhesive layer. It is characterized by satisfying the above requirements [1] to [3] when the above shear test (A) is performed.

[Adhesive layer]
The adhesive layer constituting the adhesive sheet of the present invention contains a polyfunctional epoxy compound.
A polyfunctional epoxy compound means a compound having two or more epoxy groups in the molecule.
By using an adhesive containing a polyfunctional epoxy compound, an adhesive layer satisfying the requirements [1] to [3] can be efficiently formed.

Polyfunctional epoxy compounds include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated bisphenol S type epoxy resin, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, water Added bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, pentaerythritol polyglycidyl ether, 1,6-hexanediol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, neopentyl glycol diglycidyl ether, trimethylolpropane poly glycidyl ether, 2,2-bis(3-glycidyl-4-glycidyloxyphenyl)propane, dimethyloltricyclodecane diglycidyl ether and the like.
A polyfunctional epoxy compound can be used individually by 1 type or in combination of 2 or more types.
The molecular weight of the polyfunctional epoxy compound is preferably 50-10,000, more preferably 100-5,000.

The epoxy equivalent of the polyfunctional epoxy compound is preferably 100 g/eq or more and 500 g/eq or less, more preferably 150 g/eq or more and 300 g/eq or less. By using an adhesive having a polyfunctional epoxy compound with an epoxy equivalent of 100 g/eq or more and 500 g/eq or less, it becomes easier to obtain an adhesive sheet having an adhesive layer that satisfies the above requirements [1] to [3].

The content of the polyfunctional epoxy compound is 5 to 50% by weight, preferably 10 to 40% by weight, based on the entire adhesive layer.
An adhesive layer with an excessively low content of a polyfunctional epoxy compound is less likely to satisfy the above requirements [1] and [2], and is inferior in adhesiveness. On the other hand, an adhesive layer with an excessively high polyfunctional epoxy compound content does not easily satisfy the above requirement [3] and is inferior in flexibility after curing.

The adhesive layer may contain a modified polyolefin resin as a component other than the polyfunctional epoxy compound.
By using an adhesive containing a modified polyolefin resin, it becomes easier to obtain an adhesive sheet having an adhesive layer that satisfies the above requirements [1] to [3].

The modified polyolefin resin is a polyolefin resin into which a functional group is introduced, which is obtained by modifying a polyolefin resin as a precursor using a modifying agent.

A polyolefin resin refers to a polymer containing a repeating unit derived from an olefinic monomer. The polyolefin resin may be a polymer consisting only of repeating units derived from an olefinic monomer, or may be a polymer comprising repeating units derived from an olefinic monomer and a monomer copolymerizable with the olefinic monomer. It may be a polymer consisting of a repeating unit of

The olefinic monomer is preferably an α-olefin having 2 to 8 carbon atoms, more preferably ethylene, propylene, 1-butene, isobutylene, or 1-hexene, and still more preferably ethylene or propylene. These olefinic monomers can be used singly or in combination of two or more.
Examples of monomers copolymerizable with olefinic monomers include vinyl acetate, (meth)acrylic acid esters, and styrene. Here, "(meth)acrylic acid" means acrylic acid or methacrylic acid (same below).
These olefin-based monomers and copolymerizable monomers can be used singly or in combination of two or more.

Polyolefin resins include very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene, polypropylene (PP), ethylene-propylene co- Polymers, olefin elastomers (TPO), ethylene-vinyl acetate copolymers (EVA), ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, and the like.

Modifiers used for modification treatment of polyolefin resins are compounds having functional groups in their molecules.
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, ether group. , a thioether group, a sulfone group, a phosphonic group, a nitro group, a urethane group, a halogen atom, and the like. Among these, a carboxyl group, a carboxylic anhydride group, a carboxylic acid ester group, a hydroxyl group, an ammonium group, an amino group, an imide group, and an isocyanate group are preferred, and a carboxylic anhydride group and an alkoxysilyl group are more preferred. are particularly preferred.
A compound having a functional group may have two or more functional groups in the molecule.

Modified polyolefin resins include acid-modified polyolefin resins and silane-modified polyolefin resins, and acid-modified polyolefin resins are preferable from the viewpoint of obtaining more excellent effects of the present invention.

Acid-modified polyolefin resin refers to a polyolefin resin graft-modified with an acid. For example, a polyolefin resin is reacted with an unsaturated carboxylic acid or an unsaturated carboxylic anhydride (hereinafter collectively referred to as "unsaturated carboxylic acid, etc.") to obtain a carboxyl group or a carboxylic anhydride group. is introduced (graft modification).

Unsaturated carboxylic acids to be reacted with the polyolefin resin include unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, and aconitic acid; maleic anhydride, itaconic anhydride, anhydride unsaturated carboxylic acid anhydrides such as glutaconic acid, citraconic anhydride, aconitic anhydride, norbornenedicarboxylic anhydride, and tetrahydrophthalic anhydride;
These can be used individually by 1 type or in combination of 2 or more types. Among these, maleic anhydride is preferable because an adhesive having excellent adhesive strength can be easily obtained.

The amount of the unsaturated carboxylic acid or the like to be reacted with the polyolefin resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, still more preferably 0.2 parts by mass, based on 100 parts by mass of the polyolefin resin. ~1.0 part by mass. The adhesive containing the acid-modified polyolefin resin obtained in this manner is superior in adhesive strength.

Commercially available products can also be used as the acid-modified polyolefin resin. Examples of commercially available products include ADMER (registered trademark) (manufactured by Mitsui Chemicals, Inc.), Unistol (registered trademark) (manufactured by Mitsui Chemicals, Inc.), BondyRam (manufactured by Polyram), orevac (registered trademark) (manufactured by ARKEMA), Modic (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and the like.

The silane-modified polyolefin resin is a polyolefin resin graft-modified with an unsaturated silane compound. The silane-modified polyolefin resin has a structure in which an unsaturated silane compound, which is a side chain, is graft-copolymerized with a polyolefin resin, which is a main chain. Examples include silane-modified polyethylene resins and silane-modified ethylene-vinyl acetate copolymers. Among them, silane-modified polyethylene resins such as silane-modified low-density polyethylene, silane-modified ultra-low density polyethylene, and silane-modified linear low-density polyethylene are preferred.

As the unsaturated silane compound to be reacted with the polyolefin resin, a vinylsilane compound is preferable. silane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, vinyltricarboxysilane, and the like. These can be used individually by 1 type or in combination of 2 or more types.
As for the conditions for graft polymerization of the unsaturated silane compound to the main chain polyolefin resin, a known graft polymerization method may be adopted.

The amount of the unsaturated silane compound to be reacted with the polyolefin resin is preferably 0.1 to 10 parts by mass, preferably 0.3 to 7 parts by mass, and 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyolefin resin. It is more preferably 5 to 5 parts by mass. When the amount of the unsaturated silane compound to be reacted is within the above range, the obtained adhesive containing the silane-modified polyolefin-based resin is superior in adhesive strength.

A commercially available product can also be used as the silane-modified polyolefin resin. Commercially available products include, for example, Linklon (registered trademark) (manufactured by Mitsubishi Chemical Corporation). Among them, low-density polyethylene-based Linklon, linear low-density polyethylene-based Linklon, ultra-low-density polyethylene-based Linklon, and ethylene-vinyl acetate copolymer-based Linklon can be preferably used.

Modified polyolefin-based resins may be used singly or in combination of two or more.

The number average molecular weight (Mn) of the modified polyolefin resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000.
The number average molecular weight (Mn) of the modified polyolefin resin can be obtained as a standard polystyrene conversion value by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

When the adhesive layer contains a modified polyolefin resin, the content of the modified polyolefin resin is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, based on the entire adhesive layer.
When the content of the modified polyolefin resin is within the above range, the adhesive layer more easily satisfies the above requirements [1] to [3].

The adhesive layer may contain an imidazole-based curing catalyst as a component other than the polyfunctional epoxy compound.
By using an adhesive containing an imidazole-based curing catalyst, it becomes easier to obtain an adhesive sheet having an adhesive layer that satisfies the above requirements [1] to [3].

Examples of imidazole curing catalysts include 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl -4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole and the like. Among these, 2-ethyl-4-methylimidazole is preferred.
These imidazole-based curing catalysts can be used singly or in combination of two or more.

When the adhesive layer contains an imidazole-based curing catalyst, the content of the imidazole-based curing catalyst is preferably 0.1 to 10 parts by mass, more preferably 0.2 parts by mass, based on 100 parts by mass of the polyfunctional epoxy compound. ~5 parts by mass. When the content of the imidazole-based curing catalyst is within the above range, the adhesive layer more easily satisfies the above requirements [1] to [3].

The adhesive layer may contain a silane coupling agent as a component other than the polyfunctional epoxy compound.
By using an adhesive containing a silane coupling agent, it becomes easier to obtain an adhesive sheet having an adhesive layer that satisfies the above requirements [1] to [3].

A known silane coupling agent can be used as the silane coupling agent. Among them, organosilicon compounds having at least one alkoxysilyl group in the molecule are preferred.
Silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 2-(3,4 - Silicon compounds having an epoxy structure such as -epoxycyclohexyl)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl) - amino group-containing silicon compounds such as 3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; 3-isocyanatopropyltriethoxysilane;
These silane coupling agents can be used singly 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 2% by mass, more preferably 0.05 to 1% by mass, based on the entire adhesive layer. .
When the content of the silane coupling agent is within the above range, the adhesive layer more easily satisfies the above requirements [1] to [3].

The adhesive layer may contain other components as long as the effects of the present invention are not impaired.
Other components include additives such as UV absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders and softeners.
These can be used individually by 1 type or in combination of 2 or more types.
When the adhesive layer contains these additives, the content thereof can be appropriately determined according to the purpose.

The thickness of the adhesive layer is preferably 1-25 μm, more preferably 3-20 μm.
The adhesive layer is thermosetting. That is, by heating the adhesive layer, at least the epoxy groups of the polyfunctional epoxy compound react to cure the adhesive layer.
Conditions for thermosetting the adhesive layer are not particularly limited.
The heating temperature is usually 80-200°C, preferably 90-150°C.
The heating time is usually 30 minutes to 12 hours, preferably 1 to 6 hours.
The water vapor transmission rate 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 transmission rate can be measured using a known gas transmission rate measuring device.

The adhesive layer satisfies the following requirements [1] to [3] when subjected to shear test (A) under the following conditions.
[Shear test (A)]
Two rectangular non-alkaline glass sheets with a short side of 10 mm were prepared, and on one of these non-alkali glass sheets, a square adhesive layer with a side of 10 mm was applied to a bonding area of 100 mm ² (10 mm × 10 mm). and laminated under the conditions of a temperature of 60° C., a pressure of 0.2 MPa, and a lamination speed of 0.2 m/min. Next, another sheet of alkali-free glass was placed on the surface of the adhesive layer not in contact with the alkali-free glass so that the adhesion area was 100 mm ² (10 mm × 10 mm). A laminate is obtained by lamination under conditions of a pressure of 0.2 MPa and a lamination speed of 0.2 m/min. The laminate is then heated at 100° C. for 2 hours to cure the adhesive layer. Thereafter, the laminate is allowed to stand under the conditions of 23° C. and 50% relative humidity for 24 hours to obtain a measurement sample. Using the obtained measurement sample, the shear load is measured under conditions of a shear rate of 0.1 mm/min, a room temperature of 23° C., and a relative humidity of 50%.

Requirement [1]: Measured when the maximum shear load (P ¹ _max ) is less than 10,000% shear strain.
Requirement [2]: The value of the maximum shear load (P ¹ _max ) is 100N or more.
Requirement [3]: The shear load (P ¹ _10000% ) value at a shear strain of 10,000% is 50% or more of the maximum shear load (P ¹ _max ) value.

Shear strain means the amount of displacement in the horizontal direction with respect to the thickness of the adhesive layer, and is calculated by the following formula.

For example, when the thickness of the adhesive layer is 10 μm, a shear strain of 10,000% means that the upper surface of the adhesive layer is displaced horizontally from the lower surface by 1000 μm.

The shear test (A) is a test that evaluates the shear properties of adhesives under normal conditions.
The adhesive layer of the adhesive sheet of the present invention satisfies the above requirement [1] when subjected to the shear test (A). That is, the adhesive layer of the adhesive sheet of the present invention is measured when the maximum shear load (P ¹ _max ) is less than 10,000% shear strain.
An adhesive layer that satisfies the requirement [1] is preferable from the viewpoint of sealing properties.
By containing 5 to 50% by mass of a polyfunctional epoxy resin in the adhesive layer, it becomes easier to obtain an adhesive layer that satisfies the requirement [1].

The adhesive layer of the adhesive sheet of the present invention satisfies the above requirement [2] when subjected to the shear test (A). That is, the adhesive layer of the adhesive sheet of the present invention has a maximum shear load (P ¹ _max ) value of 100 N or more.
An adhesive layer that satisfies the requirement [2] is preferable from the viewpoint of sealing properties.
By containing 5 to 50% by mass of the polyfunctional epoxy resin in the adhesive layer, it becomes easier to obtain an adhesive layer that satisfies the requirement [2].

The adhesive layer of the adhesive sheet of the present invention satisfies the above requirement [3] when subjected to the shear test (A). That is, in the adhesive layer of the adhesive sheet of the present invention, the value of shear load (P ¹ _10000% ) at shear strain of 10,000% is 50% or more of the value of maximum shear load (P ¹ _max ). is.
An adhesive layer that satisfies the requirement [3] is preferable from the viewpoint of flexibility when an object to be sealed is sealed.
By containing 5 to 50% by mass of a polyfunctional epoxy resin in the adhesive layer, it becomes easier to obtain an adhesive layer that satisfies the requirement [3].
Furthermore, by including the modified polyolefin resin in the adhesive layer, it becomes easier to obtain an adhesive layer that satisfies the requirement [3].

The adhesive layer of the adhesive sheet of the present invention preferably satisfies the following requirements [4] when a shear test (B) is performed under the following conditions.
[Shear test (B)]
A measurement sample is prepared in the same manner as in the shear test (A).
The obtained measurement sample was allowed to stand under conditions of a temperature of 60° C. and a relative humidity of 90% for 100 hours, and then under conditions of a temperature of 23° C. and a relative humidity of 50% for 24 hours. , a shear rate of 0.1 mm/min, and a room temperature of 23° C. and a relative humidity of 50%.
Requirement [4]: The value of the maximum shear load ( _P2max ) in the shear test (B) is 70% or more of the value of the _maximum shear load ( ^P1max ) in the shear test ( ^A ).

The shear test (B) is a test that evaluates the shear properties of the adhesive layer after being placed under high humidity conditions.
An adhesive layer that satisfies the requirement [4] is preferable in terms of excellent durability after sealing an object to be sealed.
By including a silane coupling agent in the adhesive layer, it becomes easier to obtain an adhesive layer that satisfies the requirement [4].

[Release film]
The adhesive sheet of the present invention may have a release film.
The release film functions as a support during the manufacturing process of the adhesive sheet and as a protective sheet for the adhesive layer until the adhesive sheet is used.
When using the adhesive sheet of the present invention, the release film is usually peeled off.

As the release film, a conventionally known one can be used. For example, there is a substrate for a release film having a release layer treated with a release agent on the substrate.
Examples of substrates for release films include paper substrates such as glassine paper, coated paper, and fine paper; laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper substrates; polyethylene terephthalate resin, polybutylene terephthalate resin, plastic films such as polyethylene naphthalate resin, polypropylene resin, polyethylene resin; and the like.
Examples of release agents 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, fluorine-based resins, and the like.

When the adhesive sheet of the present invention has a release film, the number of release films may be one or two, but usually one on each side of the adhesive layer, two in total. of release film. At this time, the two release films may be the same or different, but the two release films preferably have different release strengths. Since the peel strengths of the two peel films are different, problems are less likely to occur when using the adhesive sheet. That is, by making the peeling forces of the two peeling films different, the step of peeling the peeling films first can be performed more efficiently.

[Adhesive sheet]
The manufacturing method of the adhesive sheet is not particularly limited. For example, a casting method can be used to manufacture the adhesive sheet.
When the adhesive sheet is produced by a casting method, for example, a coating solution containing the components of the adhesive layer and a solvent is prepared, and the obtained coating solution is applied to the release-treated surface of the release film to obtain By drying the coating film, an adhesive layer with a release film is produced, and then another release film is laminated on the adhesive layer to obtain an adhesive sheet.

Solvents used for preparing the coating liquid include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; , n-hexane and n-heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane and methylcyclohexane; and the like.
These solvents can be used singly 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 methods for applying the coating liquid include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.
Drying conditions for drying the coating film include, for example, a drying temperature of 80 to 150° C. and a drying time of 30 seconds to 5 minutes.

As described above, the adhesive layer of the adhesive sheet of the present invention has the shear properties described above and is excellent in sealing properties. Therefore, by forming a sealing material using the adhesive sheet of the present invention, it is possible to extend the life of an organic EL element or the like.

3) Sealing body The sealing body of the present invention is obtained by sealing an object to be sealed using the adhesive sheet of the present invention.
The sealing body of the present invention includes, for example, a substrate, an element (object to be sealed) formed on the substrate, and a sealing material for sealing the element, The encapsulant is derived from the adhesive layer of the adhesive sheet of the present invention (hardened adhesive layer).

The substrate is not particularly limited, and various substrate materials can be used. In particular, it is preferable to use a substrate material having a high visible light transmittance. Further, it is preferable to use a material that has a high barrier performance to block moisture and gas that try to enter from the outside of the element, and that is excellent in solvent resistance and weather resistance. Specifically, transparent inorganic materials such as quartz and glass; Transparent plastics such as polystyrenes, polyarylates, polysulfones, polyolefins, etc., and the aforementioned gas barrier films;
The thickness of the substrate is not particularly limited, and can be appropriately selected in consideration of the light transmittance and the ability to block the inside and outside of the device.

Objects to be sealed include organic EL elements, organic EL display elements, liquid crystal display elements, solar cell elements, and the like.

The method for manufacturing the sealed body of the present invention is not particularly limited. For example, after the adhesive layer of the adhesive sheet of the present invention is placed on the object to be sealed, the adhesive layer of the adhesive sheet and the object to be sealed are adhered by heating.
By then curing this adhesive layer, the sealing body of the present invention can be produced.

Adhesion conditions for adhering the adhesive layer of the adhesive sheet and the object to be sealed are not particularly limited. The bonding temperature is, for example, 23-100°C, preferably 40-80°C. This adhesion treatment may be performed while applying pressure.
As the curing conditions for curing the adhesive layer, the conditions described above can be used.

The sealed body of the present invention is obtained by sealing an object to be sealed with the adhesive sheet of the present invention.
Therefore, in the sealed body of the present invention, the performance of the sealed object is maintained for a long period of time.

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is by no means limited to the following examples.
Parts and % in each example are based on mass unless otherwise specified.

[Example 1]
Acid-modified polyolefin resin (acid-modified α-olefin polymer, manufactured by Mitsui Chemicals, trade name: UNISTOL H-200, number average molecular weight: 47,000) 76.6 parts, polyfunctional epoxy compound (1) (water Added bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8034, epoxy equivalent 270 g / eq) 23.0 parts, imidazole-based curing catalyst (manufactured by Shikoku Kasei Co., trade name: Cursol 2E4MZ, 2-ethyl-4- methylimidazole) and 0.3 parts of silane coupling agent (1) (8-glycidoxyoctyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM4803) were dissolved in methyl ethyl ketone and solidified. An adhesive composition 1 with a concentration of 18% was prepared.
This adhesive composition 1 is applied onto the release-treated surface of a release film (manufactured by Lintec, trade name: SP-PET382150), and the resulting coating film is dried at 100 ° C. for 2 minutes to give a 10 μm thick adhesive. An adhesive layer was formed, and the release-treated surface of another release film (trade name: SP-PET381031, manufactured by Lintec Corporation) was adhered thereon to obtain an adhesive sheet 1.

[Example 2]
In Example 1, polyfunctional epoxy compound (2) (hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8000, epoxy equivalent: 205 g/eq) was used instead of polyfunctional epoxy compound (1). Adhesive Composition 2 was prepared in the same manner as in Example 1, except that the adhesive composition 2 was used to obtain Adhesive Sheet 2.

[Example 3]
In Example 1, polyfunctional epoxy compound (3) (hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8040, epoxy equivalent: 1100 g/eq) was used instead of polyfunctional epoxy compound (1). Adhesive Composition 3 was prepared in the same manner as in Example 1, except that the adhesive composition 3 was used to obtain Adhesive Sheet 3.

[Example 4]
In Example 1, the silane coupling agent (2) (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403) was used instead of the silane coupling agent (1). An adhesive composition 4 was prepared in the same manner as in Example 1 except for the above, and an adhesive sheet 4 was obtained using this composition.

[Example 5]
In Example 1, polyfunctional epoxy compound (4) (hydrogenated bisphenol A diglycidyl ether, manufactured by Kyoeisha Chemical Co., Ltd., trade name: Epolite 4000, epoxy equivalent 215 to 245 g/eq) was used instead of polyfunctional epoxy compound (1). ) was used to prepare an adhesive composition 5 in the same manner as in Example 1, and an adhesive sheet 5 was obtained.

[Example 6]
In Example 5, the silane coupling agent (2) (3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403) was used instead of the silane coupling agent (1). An adhesive composition 6 was prepared in the same manner as in Example 5, except for the above, and an adhesive sheet 6 was obtained using this composition.

[Comparative Example 1]
Adhesive composition 7 was prepared and adhesive sheet 7 was obtained in the same manner as in Example 1, except that polyfunctional epoxy compound (1) was not used.

[Comparative Example 2]
77 parts of n-butyl acrylate, 20 parts of methyl acrylate, 3 parts of acrylic acid, 200 parts of ethyl acetate, 2,2'-azo are added to a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen inlet tube. 0.16 part of bisisobutyronitrile was charged, and copolymerization was carried out at 70° C. in a nitrogen gas atmosphere to obtain an acrylic polymer (1) having a weight average molecular weight (Mw) of 800,000.
97.4 parts of acrylic polymer (1), 2.3 parts of trimethylolpropane adduct of tolylene diisocyanate, 0.3 parts of aluminum trisacetylacetonate, mixed solvent of toluene / ethyl acetate [mixing ratio (volume ratio ): 3/2] to prepare an adhesive composition 8 having a solid concentration of 21%. Adhesive sheet 8 was obtained in the same manner as in Example 1, except that adhesive composition 8 was used.

[Comparative Example 3]
60 parts of 2-ethylhexyl acrylate, 20 parts of methyl methacrylate, 20 parts of hydroxyethyl acrylate, 200 parts of ethyl acetate, 2,2'- 0.16 parts of azobisisobutyronitrile was charged, and copolymerization was carried out at 70° C. in a nitrogen gas atmosphere to obtain an acrylic polymer (2) having a weight average molecular weight (Mw) of 700,000.
99.5 parts of acrylic polymer (2), 0.2 parts of trimethylolpropane adduct of tolylene diisocyanate, 0.3 parts of 3-glycidoxypropyltrimethoxysilane, ethyl acetate / methyl ethyl ketone mixed solvent [mixing ratio (volume ratio): 4/1] to prepare an adhesive composition 9 having a solid concentration of 35%. Adhesive sheet 9 was obtained in the same manner as in Example 1, except that adhesive composition 9 was used.

[Comparative Example 4]
100 parts of a copolymer of isobutylene and isoprene (Exxon Butyl 268, manufactured by Nippon Butyl Co., number average molecular weight of 260,000, isoprene content of 1.7 mol%), polyisoprene rubber having a carboxylic acid functional group ( Kuraray Co., Ltd., LIR410, number average molecular weight 30,000, average number of carboxyl groups per molecule: 10) 5 parts, aliphatic petroleum resin (Nippon Zeon Co., Ltd., Quinton A100, softening point 100 ° C.) 20 parts, cross-linking agent (Epoxy compound, manufactured by Mitsubishi Chemical Corporation, TC-5) 1 part was dissolved in toluene to obtain an adhesive composition 10 having a solid content concentration of 25%. An adhesive sheet 10 was obtained in the same manner as in Example 1, except that the adhesive composition 10 was used.

The adhesive sheets 1 to 10 obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to the following tests.
[Shear test (A)]
The adhesive sheets obtained in Examples or Comparative Examples were processed into squares with a side of 10 mm.
Two rectangular non-alkaline glasses having short sides of 10 mm were prepared. Peel off one peeling film of the above square adhesive sheet, and remove the remaining adhesive sheet so that the exposed adhesive layer faces the non-alkali glass and the adhesive area is 100 mm ² (10 mm × 10 mm). They were placed on alkali glass and laminated using a pressure roller under conditions of a temperature of 60° C., a pressure of 0.2 MPa, and a lamination speed of 0.2 m/min. Next, another sheet of release film was peeled off, and another sheet of alkali-free glass was placed on the exposed adhesive layer so that the adhesion area was 100 mm ² (10 mm × 10 mm). were laminated at a temperature of 60° C., a pressure of 0.2 MPa, and a lamination speed of 0.2 m/min to obtain a laminate.
The laminate was then heated at 100° C. for 2 hours to cure the adhesive layer. After that, the laminate was allowed to stand under conditions of 23° C. and 50% relative humidity for 24 hours to obtain a measurement sample.
Using the obtained measurement sample, the shear load was measured under the condition of a shear rate of 0.1 mm/min.

[Shear test (B)]
A measurement sample was prepared in the same manner as in the shear test (A).
The obtained measurement sample was allowed to stand under conditions of a temperature of 60° C. and a relative humidity of 90% for 100 hours, and then under conditions of a temperature of 23° C. and a relative humidity of 50% for 24 hours. , the shear load was measured under the conditions of a shear rate of 0.1 mm/min.

[Evaluation test of organic EL element]
An organic EL device having as an anode a glass substrate on which an indium tin oxide (ITO) film (thickness: 100 nm, sheet resistance: 50 ohms per square) was formed was produced by the following method.
First, on the ITO film of the glass substrate, N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) (manufactured by Luminescence Technology) was deposited to 50 nm, Tris(8- Hydroxy-quinolinate)aluminum (manufactured by Luminescence Technology) was sequentially vapor-deposited at a rate of 0.1-0.2 nm/min at 50 nm to form a light-emitting layer.
On the resulting light emitting layer, as an electron injection material, lithium fluoride (LiF) (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was deposited at a rate of 0.1 nm / min to 4 nm, and then aluminum (Al) (Kojundo Chemical Laboratory Co., Ltd.) was vapor-deposited to a thickness of 100 nm at a rate of 0.1 nm/min to form a cathode, and an organic EL device was obtained.
The degree of vacuum during vapor deposition was 1×10 ⁻⁴ Pa or less in all cases.

One release film of the adhesive sheet obtained in Examples or Comparative Examples was peeled off, and the exposed adhesive layer was overlaid on the metal foil film and adhered at 60° C. using a heat laminator. Next, another release film was peeled off, and the exposed adhesive layer was overlaid so as to cover the organic EL element formed on the glass substrate, and these were adhered at 60° C. using a heat laminator. Then, the adhesive layer was cured by heating at 100° C. for 2 hours to obtain a bottom emission type electronic device in which the organic EL element was sealed.
After allowing this electronic device to stand in an environment with a temperature of 60° C. and a relative humidity of 90% for 250 hours, the organic EL element is activated, and the presence or absence of dark spots (non-light-emitting locations) is observed and evaluated according to the following criteria. did.
⊚: Dark spots are less than 40% of the light-emitting area △: Dark spots are 40% or more and less than 50% of the light-emitting area ×: Dark spots are 50% or more of the light-emitting area Table 1 shows the evaluation results.

Table 1 shows the following.
The adhesive layers of the adhesive sheets obtained in Examples 1 to 6 have excellent sealing properties, and the use of these to seal the organic EL element can suppress the occurrence of dark spots.
On the other hand, the adhesive layers of the adhesive sheets obtained in Comparative Examples 1 to 4 do not have the desired shearing properties, and are inferior in sealing properties.

Claims (9)

An adhesive sheet having a thermosetting adhesive layer containing a polyfunctional epoxy compound, an acid-modified polyolefin resin, and an imidazole curing catalyst ,
The content of the polyfunctional epoxy compound is 5 to 50% by mass in the entire adhesive layer,
The content of the acid-modified polyolefin resin is 40 to 90% by mass in the entire adhesive layer,
An adhesive sheet characterized by satisfying the following requirements (1) to (3) when a shear test (A) is performed under the following conditions.
[Shear test (A)]
Two rectangular non-alkaline glass sheets with a short side of 10 mm were prepared, and on one of these non-alkali glass sheets, a square adhesive layer with a side of 10 mm was applied to a bonding area of 100 mm ² (10 mm × 10 mm). and laminated under the conditions of a temperature of 60° C., a pressure of 0.2 MPa, and a lamination speed of 0.2 m/min. Next, another sheet of alkali-free glass was placed on the surface of the adhesive layer not in contact with the alkali-free glass so that the adhesion area was 100 mm ² (10 mm × 10 mm). A laminate is obtained by lamination under conditions of a pressure of 0.2 MPa and a lamination speed of 0.2 m/min. The laminate is then heated at 100° C. for 2 hours to cure the adhesive layer. Thereafter, the laminate is allowed to stand under the conditions of 23° C. and 50% relative humidity for 24 hours to obtain a measurement sample. Using the obtained measurement sample, the shear load is measured under the condition of a shear rate of 0.1 mm/min.
[Requirements]
Requirement [1]: Measured when the maximum shear load (P ¹ _max ) is less than 10,000% shear strain.
Requirement [2]: The value of the maximum shear load (P ¹ _max ) is 100N or more.
Requirement [3]: The shear load (P ¹ _10000% ) value at a shear strain of 10,000% is 50% or more of the maximum shear load (P ¹ _max ) value. 2. The adhesive sheet according to claim 1, which satisfies the following requirement [4] when subjected to a shear test (B) under the following conditions.
[Shear test (B)]
A measurement sample is prepared in the same manner as in the shear test (A).
The obtained measurement sample was allowed to stand under conditions of a temperature of 60° C. and a relative humidity of 90% for 100 hours, and then under conditions of a temperature of 23° C. and a relative humidity of 50% for 24 hours. , the shear load is measured under the conditions of a shear rate of 0.1 mm/min.
[Requirements]
Requirement [4]: The value of the maximum shear load ( _P2max ) in the shear test (B) is 70% or more of the value of the _maximum shear load ( ^P1max ) in the shear test ( ^A ). 3. The adhesive sheet according to claim 1 , wherein the content of the imidazole-based curing catalyst is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polyfunctional epoxy compound contained in the adhesive layer. The adhesive sheet according to any one of claims 1 to 3 , wherein the adhesive layer further contains a silane coupling agent. 5. The adhesive sheet according to claim 4 , wherein the content of the silane coupling agent is 0.01 to 2% by mass in the entire adhesive layer. The adhesive sheet according to any one of claims 1 to 5 , wherein the adhesive layer has a thickness of 1 to 25 µm. The adhesive sheet according to any one of claims 1 to 6 , further comprising a release film. A sealed body in which an object to be sealed is sealed using the adhesive sheet according to any one of claims 1 to 7 . 9. The sealing body according to claim 8 , wherein the object to be sealed is an organic EL element, an organic EL display element, a liquid crystal display element, or a solar cell element.