JP7138406B2 - Adhesive composition, adhesive sheet, and sealing body - Google Patents

Description

The present invention provides an adhesive composition that can be easily formed into a sheet and becomes a cured product that is excellent in colorless transparency, an adhesive sheet having an adhesive layer formed using this adhesive composition, and a sealed product. The present invention relates to a sealed body in which an object is 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 is thought that oxygen, moisture, etc. enter the inside of the organic EL element and deteriorate the electrodes and the organic layer. Therefore, it has been practiced to seal the organic EL element with a sealing material to prevent the infiltration of oxygen and moisture.
As a method for forming such a sealing material, a method using a thermosetting resin sheet is known.

For example, Patent Document 1 discloses (A) a polyisobutylene resin, (B) a polyisoprene resin and/or polyisobutylene resin having a functional group capable of reacting with an epoxy group, (C) a tackifying resin, and (D) an epoxy resin. A resin composition containing a resin, a resin composition sheet containing the resin composition, and the like are described.
Patent Document 1 also describes that the resin composition can be easily formed into a sheet, and that the obtained resin composition sheet is suitably used for encapsulating an organic EL element.

WO2011/062167 (US2012/0283375 A1)

According to the study of the present inventors, it was found that the cured product of the adhesive composition described in Examples of Patent Document 1 tends to be yellowish. Accordingly, there has been a demand for an adhesive composition capable of forming a cured product having excellent colorless transparency.

The present invention has been made in view of the above circumstances, and provides an adhesive composition that is easy to mold into a sheet and gives a cured product that is excellent in colorless transparency, and adhesion formed using this adhesive composition. An object of the present invention is to provide an adhesive sheet having an agent layer, and a sealing body in which an object to be sealed is sealed with the adhesive sheet.

As a result of intensive studies to solve the above problems, the present inventors have found that a combination of a modified polyolefin resin and a polyfunctional epoxy resin having no aromatic ring is used, and a compound having a phenoxy structure is not used, or is The inventors have found that by reducing the amount used, it is possible to obtain an adhesive composition that can be easily molded into a sheet and gives a cured product that is excellent in colorless transparency, and has completed the present invention.

Thus, according to the present invention, the following adhesive compositions (1) to (9), adhesive sheets (10) to (12), and sealing bodies (13) and (14) are provided.
(1) An adhesive composition containing the following components (A) and (B), which was formed into a sheet having a thickness of 10 μm and then cured. An adhesive characterized by having a b* value of −2.0 to +2.0 in the CIE L*a*b* color system defined in JIS Z 8729-1994 when the object is colorimetrically measured. Composition.
(A) component: modified polyolefin resin (B) component: polyfunctional epoxy compound having no aromatic ring (2) The adhesive composition according to (1), wherein the component (A) is an acid-modified polyolefin resin thing.
(3) The adhesive composition according to (1) or (2), wherein the content of component (B) is 1 to 200 parts by mass per 100 parts by mass of component (A).
(4) The adhesive composition according to any one of (1) to (3), further comprising the following component (C).
Component (C): a tackifier having a softening point of 80° C. or higher (5) The content of component (C) is 1 to 200 parts by mass per 100 parts by mass of component (A), (4) The adhesive composition according to .
(6) The adhesive composition according to any one of (1) to (5), further comprising component (D) below.
(D) component: imidazole-based curing catalyst (7) The adhesive composition according to (6), wherein the content of component (D) is 1 to 10 parts by mass per 100 parts by mass of component (B). thing.
(8) The adhesive composition according to any one of (1) to (7), further comprising component (E) below.
Component (E): Silane coupling agent (9) The content of component (E) is 0.01 to 10 parts by mass with respect to 100 parts by mass of component (A), adhesion according to (8) agent composition.
(10) An adhesive sheet having an adhesive layer, wherein the adhesive layer is formed using the adhesive composition according to any one of (1) to (9).
(11) The adhesive sheet according to (10), wherein the adhesive layer has a thickness of 5 to 25 μm.
(12) The adhesive sheet according to (10) or (11), further comprising a release film.
(13) A sealed body in which an object to be sealed is sealed using the adhesive sheet according to any one of (10) to (12).
(14) The sealing body according to (13), 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.

According to the present invention, there is provided an adhesive composition that is easily molded into a sheet and gives a cured product having excellent colorless transparency, an adhesive sheet having an adhesive layer formed using this adhesive composition, and a substrate A sealed body is provided in which a sealed object is sealed with the adhesive sheet.
In the present invention, "to give a cured product having excellent colorless transparency" means to give a cured product having a high light transmittance and a small haze value, and to form the adhesive composition into a sheet having a thickness of 10 µm. Then, when measuring the color of the cured product, the b * value in the CIE L * a * b * color system specified in JIS Z 8729-1994 is -2.0 to +2.0 Say something.

Hereinafter, the present invention will be described in detail by dividing into 1) adhesive composition, 2) adhesive sheet, and 3) encapsulant.

1) Adhesive composition The adhesive composition of the present invention is an adhesive composition containing the following components (A) and (B). When the color is measured after molding into a shape and then curing it, the b* value in the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0 to +2.0.
(A) component: modified polyolefin resin (B) component: polyfunctional epoxy compound having no aromatic ring

(A) Component: Modified Polyolefin Resin The adhesive composition of the present invention contains a modified polyolefin resin as the (A) component.
Since the adhesive composition of the present invention contains a modified polyolefin resin, it has excellent adhesive strength. Also, by using an adhesive composition containing a modified polyolefin resin, a relatively thin adhesive layer can be efficiently formed.

A modified polyolefin resin is a polyolefin resin into which a functional group has been introduced. The modified polyolefin resin can be obtained by subjecting a polyolefin resin as a precursor to modification treatment using a modifier.

A polyolefin resin refers to a polymer containing a repeating unit derived from an olefinic monomer. The polyolefin resin may be a polymer composed of one or two types of repeating units derived from olefinic monomers, or one or more types of repeating units derived from olefinic monomers and an olefinic monomer. It may be a polymer composed of one or more repeating units derived from monomers copolymerizable with the polymer. Moreover, when the polyolefin resin is a copolymer, the polymerization form of the copolymer is not particularly limited, and it may be a block copolymer or a random copolymer.

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. The 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, (meth)acrylic acid esters, and styrene. Here, "(meth)acrylic acid" means acrylic acid or methacrylic acid (same below).
The monomers copolymerizable with the olefinic monomers may 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.

An acid-modified polyolefin resin is a resin obtained by graft-modifying a polyolefin resin 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 glutaconic acid, citraconic anhydride, aconitic anhydride, norbornenedicarboxylic anhydride, tetrahydrophthalic anhydride, and other unsaturated carboxylic anhydrides;
These can be used singly or in combination of two or more.
Among these, maleic anhydride is preferable because it is easy to obtain an adhesive composition having excellent adhesive strength.

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. When the amount of the unsaturated carboxylic acid or the like to be reacted is within the above range, the obtained adhesive composition containing the acid-modified polyolefin-based resin has excellent 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.

A silane-modified polyolefin resin is a resin obtained by graft-modifying a polyolefin resin 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 thereof include silane-modified polyethylene resins and silane-modified ethylene-vinyl acetate copolymers, and 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.

Examples of unsaturated silane compounds to be reacted with the polyolefin resin include vinylsilane compounds; allylsilane compounds such as allyltrimethoxysilane and allyltriethoxysilane; 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane ( meth) acryloxy group-containing silane compounds; and the like, and vinylsilane compounds are preferred from the viewpoint of versatility, adhesiveness, and the like. Here, the (meth)acryloxy group represents an acryloxy group or a methacryloxy group (same below).

Vinylsilane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltri methylenedioxysilane, 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 of the polyolefin resin, a conventional 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, more preferably 0.3 to 7 parts by mass, with respect to 100 parts by mass of the polyolefin resin. 0.5 to 5 parts by mass is more preferable. When the amount of the unsaturated silane compound to be reacted is within the above range, the resulting adhesive composition containing the silane-modified polyolefin resin will have excellent 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 from 10,000 to 2,000,000, more preferably from 20,000 to 1,500, for the reason that the effects of the present invention are easily obtained. 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.

(B) Component: Polyfunctional Epoxy Compound Having No Aromatic Ring The adhesive composition of the present invention contains a polyfunctional epoxy compound having no aromatic ring as the component (B).
Since the adhesive composition of the present invention contains a polyfunctional epoxy compound, its cured product has excellent water vapor barrier properties.
Moreover, since the component (B) used in the present invention is a polyfunctional epoxy compound having no aromatic ring, an adhesive composition containing this compound gives a cured product with excellent transparency. That is, a polyfunctional epoxy compound having no aromatic ring has higher compatibility with the modified polyolefin resin of component (A) than a polyfunctional epoxy compound having an aromatic ring. Therefore, by using the component (B) as the polyfunctional epoxy compound, it is possible to obtain an adhesive composition that gives a cured product with a higher light transmittance and a smaller haze.
From this point of view, the adhesive composition of the present invention preferably does not contain a polyfunctional epoxy compound having an aromatic ring. In particular, as will be described later, the b* value of the cured product of the adhesive composition of the present invention is desirably close to 0. Therefore, those that do not contain a polyfunctional epoxy compound having a phenoxy structure in the molecule are preferred. preferable.
Here, the phenoxy structure refers to the partial structures shown in (a) and (b) below (same below).

In the above formulas (a) and (b), A1 represents ^an unsubstituted or substituted aryl group, and ^A2 represents an unsubstituted or substituted arylene group.
The aryl group of unsubstituted or substituted aryl group includes phenyl group, 1-naphthyl group, 2-naphthyl group and the like.
Arylene groups of unsubstituted or substituted arylene groups include 1,4-phenylene group, 1,3-phenylene group, 1,2-phenylene group, 1,5-naphthylene group, 2,6-naphthylene group and the like. is mentioned.
Aryl groups having substituents and substituents of arylene groups having substituents include alkyl groups having 1 to 6 monolayers such as methyl, isopropyl and t-butyl; methoxy, isopropoxy, t -C 1-6 alkoxy group such as butoxy group; halogen atom such as fluorine atom, chlorine atom, bromine atom;

A polyfunctional epoxy compound means a compound having two or more epoxy groups in the molecule.
Component (B) includes hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated bisphenol S type epoxy resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, and hydrogenated bisphenol. S diglycidyl ether, pentaerythritol polyglycidyl ether, 1,6-hexanediol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, neopentyl glycol diglycidyl ether, trimethylolpropane polyglycidyl ether, 2,2-bis(3 -glycidyl-4-glycidyloxyphenyl)propane, dimethyloltricyclodecane diglycidyl ether, dicyclopentadiene dimethanol 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 number average molecular weight (Mn) of the polyfunctional epoxy compound (B) is preferably from 100 to 3,000, more preferably from 200 to 1,500, because the effects of the present invention can be easily obtained.

The epoxy equivalent of the (B) component polyfunctional epoxy compound is preferably 100 g/eq to 500 g/eq, more preferably 150 g/eq to 300 g/eq. By using an adhesive composition containing a polyfunctional epoxy compound as the component (B) having an epoxy equivalent of 100 g/eq or more and 500 g/eq or less, a low outgassing sealing material can be efficiently formed.

The adhesive composition of the present invention may contain a tackifier having a softening point of 80° C. or higher as component (C) in addition to components (A) and (B).
The adhesive composition containing component (C) can easily maintain a constant shape and can form a sheet-like adhesive layer more efficiently.

The tackifier (C) is not particularly limited as long as it has a softening point of 80°C or higher. For example, rosin-based resins such as polymerized rosin, polymerized rosin esters, and rosin derivatives; polyterpene resins, aromatic modified terpene resins and their hydrides, terpene-based resins such as terpene phenolic resins; coumarone-indene resins; Petroleum resins such as aromatic petroleum resins and their hydrides, aliphatic/aromatic copolymer petroleum resins; low molecular weight polymers of styrene or substituted styrene; α-methylstyrene homopolymer resins, α-methylstyrene/ Styrene copolymer resin, styrene monomer/aliphatic monomer copolymer resin, styrene monomer/α-methylstyrene/aliphatic monomer copolymer resin, styrene monomer homopolymer resin, styrene monomer/ styrenic resins such as aromatic monomer copolymer resins; and the like. These tackifiers can be used singly or in combination of two or more.
Among these, styrenic resins are preferable, and styrenic monomer/aliphatic monomer copolymer resins are more preferable.

By using a tackifier having a softening point of 80° C. or higher, an adhesive composition having excellent adhesiveness at high temperatures can be obtained. In addition, workability is improved when the adhesive composition is formed into a sheet.

When the adhesive composition of the present invention contains component (C), its content is preferably 1 to 200 parts by mass, more preferably 10 to 150 parts by mass, per 100 parts by mass of component (A). is. When the component (C) is included, if the content of the component (C) is too small, it may be difficult to form the adhesive composition into a sheet. On the other hand, if the content of component (C) is too high, the adhesive layer may become brittle.

The adhesive composition of the present invention may contain an imidazole-based curing catalyst as component (D) in addition to components (A) and (B).
By using an adhesive composition containing an imidazole-based curing catalyst, it becomes easier to obtain a cured product having excellent adhesiveness even at high temperatures.

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 composition of the present invention contains component (D), its content is preferably 1 to 10 parts by mass, more preferably 2 to 5 parts by mass, per 100 parts by mass of component (A). is. A cured product of an adhesive composition having an imidazole-based curing catalyst content within this range has excellent adhesiveness even at high temperatures.

The adhesive composition of the present invention may contain a silane coupling agent as component (E) in addition to components (A) and (B).
By using an adhesive composition containing a silane coupling agent, it becomes easier to obtain a cured product having excellent adhesive strength under normal temperature and high temperature environments.

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, 3-(meth)acryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 8 -Silicon compounds having an epoxy structure such as glycidoxyoctyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -amino group-containing silicon compounds such as aminopropyltrimethoxysilane, N-(2-aminoethyl)-8-aminooctyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; chloropropyltrimethoxysilane; 3-isocyanatopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride; and the like.
These silane coupling agents can be used singly or in combination of two or more.

When the adhesive composition of the present invention contains a silane coupling agent, the content thereof is preferably 0.01 to 10 parts by mass, more preferably 0.02 parts by mass, per 100 parts by mass of component (A). ~5 parts by mass.

The adhesive composition of the invention may contain a solvent.
Examples of solvents include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as 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.

The adhesive composition of the present invention 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 singly or in combination of two or more.
When the adhesive composition of the present invention contains these additives, the content thereof can be appropriately determined according to the purpose.

The adhesive composition of the present invention can be prepared by appropriately mixing and stirring predetermined components according to a conventional method.

The adhesive composition of the present invention was molded into a sheet with a thickness of 10 μm, and then cured. The b* value in the color system is -2.0 to +2.0.
In the above-described colorimetry, the method of forming the adhesive composition into a sheet and the method of curing thereof can be the methods described later.

In the L*a*b* color system, L* indicates lightness, and a* and b* indicate hue and saturation, respectively. Red direction when a* is positive, green direction when a* is negative value, yellow direction when b* is positive value, and blue direction when b* is negative value. Indicates saturation. The smaller the absolute values of a* and b*, the more colorless.
The b* value of the cured product of the adhesive composition of the present invention is -2.0 to +2.0, preferably -1.0 to +2.0, more preferably 0.0 to 2.0, most preferably 0.0 to 1.0. The cured product of the adhesive composition of the present invention is less biased in both the yellow direction (+b*) and the blue direction (-b*). The adhesive composition that gives a cured product with b* in the above range has the advantages of high total light transmittance, low haze value, and very little coloration, and is suitable for sealing light-emitting devices such as organic EL elements. Suitable for use as a sealing material.
The b* value in the CIE L*a*b* color system can be measured by the method described in Examples.

The b* value of the cured product is affected by the compound having an aromatic ring (phenoxy structure) contained in the adhesive composition. Therefore, an adhesive composition that gives a cured product with a b* value of -2.0 to +2.0 does not use a compound having an aromatic ring (phenoxy structure), or reduces the amount used to improve efficiency. Good and easy to prepare.
The adhesive composition of the present invention does not contain a compound having an aromatic ring (phenoxy structure), or has a low content of a compound having an aromatic ring (phenoxy structure) (with respect to the entire adhesive composition, the solid content and 5% by mass or less) is preferable, and those containing no compound having an aromatic ring (phenoxy structure) are more preferable.

The adhesive composition of the present invention was molded into a sheet with a thickness of 10 μm, and then cured. Using this as a test piece, the total light transmittance and haze value were measured. It is preferably 85% or more, more preferably 90% or more. Although there is no particular upper limit for the total light transmittance, it is usually 95% or less. Also, the haze value is preferably 1.4% or less, more preferably 1% or less. Although there is no particular lower limit for the haze value, it is usually 0.5% or more.
The total light transmittance can be measured according to JIS K7361:1997. A haze value can be measured according to JIS K7136:2000.

As described above, in the adhesive composition of the present invention, a modified polyolefin resin is used as the component (A), and an aromatic ring, which is a polyfunctional epoxy compound highly compatible with the component (A), is added. A polyfunctional epoxy compound that does not have is used as the (B) component. As a result, the cured product of the adhesive composition of the present invention has a high total light transmittance and a small haze value.

The adhesive composition of the present invention is easily formed into a sheet and has excellent colorless transparency. Therefore, the adhesive composition of the present invention is suitable for optical applications.

2) Adhesive Sheet The adhesive sheet of the present invention is an adhesive sheet having an adhesive layer, and the adhesive layer is formed using the adhesive composition of the present invention.

Although the thickness of the adhesive layer of the adhesive sheet is not particularly limited, it is usually 5 to 25 μm, preferably 10 to 20 μm.
An adhesive layer having a thickness within the above range is suitably used as a sealing material.

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.

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, the adhesive composition of the present invention is applied to the release-treated surface of the release film using a known method, and the resulting coating film is dried to obtain a release film-attached film. An adhesive sheet can be obtained by manufacturing an adhesive layer and then laminating another release film on the adhesive layer.

Examples of methods for applying the adhesive composition include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating and the like.
Drying conditions for drying the coating film include, for example, 80 to 150° C. for 30 seconds to 5 minutes.

The adhesive layer of the adhesive sheet of the present invention has thermosetting properties.
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 state after the adhesive layer of the present invention has been thermally cured refers to a state in which it is cured to the extent that it can be used for sealing an object to be sealed.

The peeling adhesive strength of the adhesive layer after curing treatment at 23° C. is usually 1 to 100 N/25 mm, preferably 10 to 50 N/25 mm, and the peeling adhesive strength at 85° C. is usually 1 to 100 N. /25mm, preferably 5 to 50N/25mm.
The peeling adhesive strength at 23 ° C. conforms to JIS Z0237: 2009, under a temperature of 23 ° C. and a relative humidity of 50% and a temperature of 85 ° C. (humidity is not controlled). A peel test can be performed under the conditions and measured.
The water vapor transmission rate of the adhesive layer after curing 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 under the conditions of 40° C. and 90% RH using a known water vapor transmission rate measuring device, for example, a permeability measuring machine “L80-5000” manufactured by LYSSY.

As described above, the cured product of the adhesive layer of the adhesive sheet of the present invention is excellent in colorless transparency. Therefore, the adhesive sheet of the present invention is suitably used for sealing organic EL devices, organic EL display devices, liquid crystal display devices, solar cell devices and 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 above 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, and then the adhesive layer is cured. The sealed body of the present invention can be manufactured by allowing the

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) 100 parts, polyfunctional epoxy compound (1) (hydrogenated bisphenol A-type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8000, epoxy equivalent: 205 g / eq) 25 parts, imidazole curing catalyst (manufactured by Shikoku Kasei Co., Ltd., trade name: Cursol 2E4MZ, 2-ethyl-4-methylimidazole) 0.25 part and 0.1 part of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM6803) were dissolved in methyl ethyl ketone to prepare an adhesive composition 1 having a solid concentration of 20%.
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, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (2) (hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8034, epoxy equivalent: 270 g / eq) was used. Adhesive Composition 2 was prepared in the same manner as in Example 1 except that it was used, and Adhesive Sheet 2 was obtained using this.

[Example 3]
In Example 1, polyfunctional epoxy compound (3) (manufactured by ADEKA, trade name: EP-4088L, dicyclopentadiene dimethanol diglycidyl ether, epoxy equivalent: 165 g/eq) was used instead of polyfunctional epoxy compound (1). ) was used to prepare an adhesive composition 3 in the same manner as in Example 1, and an adhesive sheet 3 was obtained.

[Example 4]
Acid-modified polyolefin resin (α-olefin polymer, manufactured by Mitsui Chemicals, Inc., trade name: UNISTOL H-200, number average molecular weight: 47,000) 100 parts, polyfunctional epoxy compound (1) (hydrogenated bisphenol A type Epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8000) 100 parts, tackifier (styrene monomer / aliphatic monomer copolymer resin, manufactured by Mitsui Chemicals, trade name: FTR6100) 50 parts, imidazole curing catalyst ( Shikoku Kasei Co., Ltd., trade name: Cursol 2E4MZ, 2-ethyl-4-methylimidazole) 1 part, and silane coupling agent (Shin-Etsu Chemical Co., trade name: KBM6803) 0.1 part was dissolved in methyl ethyl ketone. , an adhesive composition 4 having a solid content concentration of 30% was prepared.
Adhesive Sheet 4 was obtained in the same manner as in Example 1, except that Adhesive Composition 4 was used instead of Adhesive Composition 1.

[Example 5]
In Example 4, instead of the polyfunctional epoxy compound (1), polyfunctional epoxy compound (2) (hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8034) was used, except that An adhesive composition 5 was prepared in the same manner as in Example 4, and an adhesive sheet 5 was obtained using this composition.

[Example 6]
In Example 4, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (4) (hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8040, epoxy equivalent: 1100 g/eq) was used. Adhesive composition 6 was prepared in the same manner as in Example 4, except that it was used, and adhesive sheet 6 was obtained.

[Example 7]
In Example 4, in the same manner as in Example 4, except that the polyfunctional epoxy compound (3) (manufactured by ADEKA, trade name: EP-4088L) was used instead of the polyfunctional epoxy compound (1). An adhesive composition 7 was prepared and an adhesive sheet 7 was obtained using this.

[Comparative Example 1]
In Example 4, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (5) (unhydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: jER828, epoxy equivalent: 190 g/eq). An adhesive composition 8 was prepared in the same manner as in Example 1, except that the was used, and an adhesive sheet 8 was obtained.

The adhesive sheets 1 to 8 obtained in Examples 1 to 7 and Comparative Example 1 were analyzed as follows. The results are shown in Table 1.
[Total light transmittance and haze measurement]
One release film of the adhesive sheet obtained in Examples or Comparative Examples was peeled off to expose the adhesive layer. This adhesive sheet was placed on soda lime glass so that the exposed adhesive layer faced the soda lime glass, and then they were laminated at 23° C. using a laminator. After peeling and removing the other release film, these were heated at 100° C. for 2 hours to cure the adhesive layer and obtain a test piece.
The total light transmittance and haze of the obtained test piece were measured using a total light transmittance measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH-5000).

[Colorimetry]
A test piece similar to that used in the total light transmittance and haze measurements was prepared.
For the obtained test piece, the color value b* specified by the CIE1976L*a*b* color system is measured in accordance with JIS Z 8729-1994 using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3200). measured by

Table 1 shows the following.
The cured products of the adhesive layers of the adhesive sheets 1 to 7 obtained in Examples 1 to 7 have a high total light transmittance and a low haze value. Furthermore, its b* value is from -2.0 to +2.0.
On the other hand, the cured product of the adhesive layer of the adhesive sheet 8 obtained in Comparative Example 1 has a large haze value and is inferior in transparency.

Claims (12)

An adhesive sheet having an adhesive layer,
The adhesive layer isthe below describedAdhesive composition of1Formed using, with thermosettingAdhesive sheet that is one.
[Adhesive composition 1]
An adhesive composition containing the following components (A), (B), and (D),
This adhesive composition was molded into a sheet with a thickness of 10 μm, and then cured. An adhesive composition characterized in that the b* value in the system is from -2.0 to +2.0.
(A) component: modified polyolefin resin
Component (B): A polyfunctional epoxy compound having no aromatic ring and having an epoxy equivalent of 100 g/eq or more and 500 g/eq or less
(D) component: imidazole-based curing catalyst 2. The adhesive sheet according to claim 1 , wherein the adhesive layer has a thickness of 5 to 25 μm. 3. The adhesive sheet according to claim 1, further comprising a release film. The adhesive sheet according to any one of claims 1 to 3, wherein the component (A) is an acid-modified polyolefin resin. The adhesive sheet according to any one of claims 1 to 4, wherein the content of component (B) is 1 to 200 parts by mass per 100 parts by mass of component (A). The adhesive sheet according to any one of claims 1 to 5, wherein the adhesive composition 1 further contains the following component (C).
(C) component: a tackifier with a softening point of 80°C or higher 7. The adhesive sheet according to claim 6, wherein the content of component (C) is 1 to 200 parts by mass per 100 parts by mass of component (A). The adhesive sheet according to any one of claims 1 to 7, wherein the content of component (D) is 1 to 10 parts by mass per 100 parts by mass of component (B). The adhesive sheet according to any one of claims 1 to 8, wherein the adhesive composition 1 further contains the following component (E).
(E) component: silane coupling agent 10. The adhesive sheet according to claim 9, wherein the content of component (E) is 0.01 to 10 parts by mass per 100 parts by mass of component (A). A sealed body obtained by sealing an object to be sealed using the adhesive sheet according to any one of claims 1 to 10 . 12. The sealing body according to claim 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.