TWI794234B - Adhesive composition, adhesive sheet and sealing body - Google Patents

Abstract

The adhesive composition of the present invention is an adhesive composition containing: (A) component: modified polyolefin resin, and (B) component: polyfunctional epoxy compound without aromatic ring, characterized in that: When the adhesive composition is formed into a sheet with a thickness of 10 μm, and then hardened and measured for color, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0~+2.0. The present invention also provides an adhesive sheet having an adhesive layer formed using the adhesive composition, and a sealed body in which a sealant is sealed with the adhesive sheet. According to the present invention, it is possible to provide an adhesive composition that can be easily molded into a sheet and can be a cured product with excellent colorless transparency, and an adhesive sheet having an adhesive layer formed using the adhesive composition, and a sealant A sealing body in which objects are sealed by using the above-mentioned adhesive sheet.

Description

Adhesive composition, adhesive sheet and sealing body

The present invention relates to an adhesive composition that can be easily formed into a sheet and can be an excellent colorless and transparent cured product, an adhesive sheet having an adhesive layer formed using the adhesive composition, and an object to be sealed by using the above-mentioned adhesive composition. Lamellar sealing body.

In recent years, organic EL elements have attracted attention because they are light-emitting elements that can emit light with high brightness even when driven by low-voltage direct current. However, the organic EL element tends to suffer from a problem in that light-emitting characteristics such as light-emitting brightness, light-emitting efficiency, and light-emitting uniformity decrease over time. The cause of this problem of lowering the luminescence characteristics is considered to be that oxygen, moisture, etc. permeate into the organic EL element to degrade electrodes and organic layers. Therefore, the organic EL element is sealed by using 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 records: (A) polyisobutylene resin, (B) polyisoprene resin and/or polyisobutylene resin having functional groups capable of reacting with epoxy groups, (C) tackifying resin , and (D) a resin composition of an epoxy resin; and a resin composition sheet containing the resin composition; and the like. Patent Document 1 also records that the resin composition can be easily formed into sheets, and the obtained resin composition sheets are quite suitable for sealing organic EL elements. [Prior Art Documents] [Patent Documents]

[Patent Document 1] WO2011/062167 (US2012/0283375 A1)

(Problem to be solved by the invention)

According to the examination of the present inventors, it is known that the cured product of the adhesive composition described in the examples of Patent Document 1 tends to be yellowish. Therefore, an adhesive composition capable of forming a more excellent colorless and transparent cured product is expected.

The present invention has been accomplished in view of the above facts, and aims to provide: an adhesive composition that can be easily formed into a sheet and can provide an excellent colorless and transparent cured product; A layered adhesive sheet, and a sealing body in which the object to be sealed is sealed by the above-mentioned adhesive sheet. (means to solve the problem)

The inventors of the present invention conducted in-depth studies to solve the above-mentioned problems, and found that a combination of modified polyolefin-based resin and polyfunctional epoxy resin not having an aromatic ring was used, and a compound with a phenoxy structure was not used, or reduced The amount used can provide an adhesive composition that can be easily formed into a thin sheet and can provide an excellent colorless and transparent hardened product, thus completing the present invention.

The reason is that according to the present invention, the following adhesive compositions (1)-(9), adhesive sheets (10)-(12), and sealing bodies of (13) and (14) are provided. (1) An adhesive composition comprising the following (A) component and (B) component, characterized in that the adhesive composition is formed into a sheet with a thickness of 10 μm, and then hardened And when measuring the color, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0~+2.0. Component (A): modified polyolefin resin (B) component: polyfunctional epoxy compound without aromatic ring (2) The adhesive composition as described in (1), wherein the above-mentioned component (A) is Acid modified polyolefin resin. (3) The adhesive composition as described in (1) whose content of the said (B) component is 1-200 mass parts with respect to 100 mass parts of said (A) components. (4) The adhesive composition as described in (1) which contains the following (C)component further. Component (C): Tackifier having a softening point of 80° C. or higher (5) The adhesive composition as described in (4), wherein the content of the component (C) is 100 parts by mass of the component (A) The amount is 1 to 200 parts by mass. (6) The adhesive composition as described in (1) which contains the following (D) component further. (D) Component: imidazole-based hardening catalyst (7) The adhesive composition as described in (6), wherein the content of the above-mentioned (D) component is 1 to 10 parts by mass with respect to 100 parts by mass of the above-mentioned (B) component parts by mass. (8) The adhesive composition as described in (1) which contains the following (E) component further. Component (E): silane coupling agent (9) The adhesive composition described in (8), wherein the content of the component (E) is 0.01 to 10 parts by mass relative to 100 parts by mass of the component (A) . (10) An adhesive sheet having an adhesive layer, wherein the adhesive layer is formed using the adhesive composition described in any one of (1) to (9). (11) The adhesive sheet according to (10), wherein the thickness of the adhesive layer is 5 to 25 μm. (12) The adhesive sheet as described in (10), which is further provided with a release film. (13) A sealing body, which is sealed by using the adhesive sheet described in any one of (10) to (12). (14) The sealed 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. [Invention effect]

According to the present invention, there can be provided an adhesive composition that can be easily formed into a sheet and can provide a cured product with excellent colorless transparency, an adhesive sheet having an adhesive layer formed using the adhesive composition, and an object to be sealed by using the above-mentioned Adhesive sheet-sealed sealing body. The so-called "providing a cured product with excellent colorless transparency" in the present invention refers to providing a cured product with a high light transmittance and a small haze value, and forming the adhesive composition into a sheet with a thickness of 10 μm, and then hardening and carrying out When measuring color, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0~+2.0.

Hereinafter, 1) the adhesive composition, 2) the adhesive sheet, and 3) the sealing body of the present invention will be described in detail.

1) Adhesive composition The adhesive composition of the present invention is an adhesive composition containing the following (A) component and (B) component, wherein the adhesive composition is shaped into a sheet with a thickness of 10 μm, and then When hardening and measuring the color, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0~+2.0. (A) component: modified polyolefin resin (B) component: polyfunctional epoxy compound without aromatic ring

Component (A): modified polyolefin resin The adhesive composition of the present invention is a modified polyolefin resin containing component (A). The adhesive composition of the present invention is excellent in adhesive strength by containing the modified polyolefin resin. Also, by using an adhesive composition containing a modified polyolefin resin, a thinner adhesive layer can be efficiently formed.

The modified polyolefin resin is a polyolefin resin introduced with functional groups. The modified polyolefin resin can be obtained by modifying the precursor polyolefin resin with a modifying agent.

The so-called "polyolefin resin" refers to a polymer containing repeating units derived from olefinic monomers. Polyolefin resins can be polymers composed of one or two repeating units derived from olefinic monomers, or can be composed of one or more repeating units derived from olefinic monomers, and can be copolymerized with olefinic monomers. A polymer composed of one or more repeating units derived from a monomer. In addition, when the polyolefin resin is a copolymer, the polymerization form of the copolymer is not particularly limited, and may be a block copolymer or a random copolymer.

The olefin-based monomer is preferably an α-olefin having 2 to 8 carbon atoms, more preferably ethylene, propylene, 1-butene, isobutene, or 1-hexene, and particularly preferably ethylene or propylene. These olefin-based monomers may be used alone or in combination of two or more. Monomers that can be copolymerized with olefinic monomers include, for example, vinyl acetate, (meth)acrylate, styrene, and the like. Here, "(meth)acryl" means acryl or methacryl (the same applies hereinafter). The monomer system copolymerizable with the olefin-based monomer may be used alone or in combination of two or more.

Examples of polyolefin resins include: ultra-low-density polyethylene (VLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene, poly Propylene (PP), ethylene-propylene copolymer, olefin-based elastomer (TPO), ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer wait.

The modifier used for modifying polyolefin resin is a compound with functional groups in the molecule. Examples of functional groups include: carboxyl group, carboxylic anhydride group, carboxylate group, hydroxyl group, epoxy group, amido group, ammonium group, nitrile group, amine group, imide group, isocyanate group, acetyl group, sulfur Alcohol group, ether group, thioether group, sulfo group, phosphino group, nitro group, urethane group, halogen atom, etc. Among them, carboxyl group, carboxylic acid anhydride group, carboxylate group, hydroxyl group, ammonium group, amino group, imide group, isocyanate group are preferred, carboxylic anhydride group and alkoxysilyl group are more preferred, especially Carboxylic anhydride group. Compounds with functional groups can also have two or more functional groups in the molecule

Modified polyolefin resins include, for example, acid-modified polyolefin resins and silane-modified polyolefin resins, and acid-modified polyolefin resins are preferred from the viewpoint of obtaining better effects of the present invention.

The so-called "acid-modified polyolefin-based resin" refers to a polyolefin resin that is graft-modified with an acid. For example, polyolefin resin is reacted with unsaturated carboxylic acid or unsaturated carboxylic acid anhydride (hereinafter, these are also collectively referred to as "unsaturated carboxylic acid, etc.") to introduce carboxyl group or carboxylic anhydride group (graft modification).

Unsaturated carboxylic acids reacted with polyolefin resins, such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitum Unsaturated carboxylic acids such as acid; maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, nor-alkenedicarboxylic anhydride, tetrahydrophthalic anhydride and other unsaturated carboxylic anhydrides. These can be used individually by 1 type or in combination of 2 or more types. Among these, maleic anhydride is preferable from the viewpoint of being easy to obtain an adhesive composition having a higher adhesive strength.

The amount of unsaturated carboxylic acid or the like to react with the polyolefin resin is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and most preferably 0.2 to 1.0 parts by mass relative to 100 parts by mass of the polyolefin resin . When the amount of the unsaturated carboxylic acid or the like to be reacted is within the above-mentioned range, the adhesive composition containing the obtained acid-modified polyolefin-based resin can become more excellent in adhesive strength.

As the acid-modified polyolefin-based resin, a commercially available one can also be used. Commercially available products include, for example, ADMER (registered trademark) (manufactured by Mitsui Chemicals), UNISTOLE (registered trademark) (manufactured by Mitsui Chemicals), Bondy Ram (manufactured by Polyram), orevac (registered trademark) (manufactured by ARKEMA), MODIC (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and the like.

The so-called "silane-modified polyolefin-based resin" refers to the graft modification of polyolefin resin by using unsaturated silane compound. The silane-modified polyolefin resin has a structure in which unsaturated silane compounds belonging to side chains are grafted and copolymerized on the main chain polyolefin resin. For example: silane-modified polyethylene resin and silane-modified ethylene-vinyl acetate copolymer. Among them, preferred are silane-modified polyethylene resins such as silane-modified low-density polyethylene, silane-modified ultra-low-density polyethylene, and silane-modified linear low-density polyethylene.

Unsaturated silane compounds that react with the above-mentioned polyolefin resins include, for example, vinyl silane compounds; allyl silane compounds such as allyl trimethoxysilane and allyl triethoxysilane; 3-acryl (Meth)acryloxy-containing silane compounds such as oxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane are preferred vinyl silane compounds from the viewpoints of versatility and adhesiveness. . Here, (meth)acryloxy means acryloxy or methacryloxy (the same applies hereinafter).

Examples of vinyl silane compounds include: vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tripropoxysilane, vinyl triisopropoxysilane, vinyl tributoxysilane, vinyl tripentoxysilane, Ethylenetriphenoxysilane, Ethylenetribenzyloxysilane, Ethylenetrimethylenedioxysilane, Ethylenetriethylenedioxysilane, Ethylenetrioxysilane, Ethylenetriacetyloxysilane, Ethylenetricarboxysilane wait. These can be used individually by 1 type or in combination of 2 or more types. When graft-polymerizing the unsaturated silane compound to the polyolefin resin belonging to the main chain, the condition is that a well-known conventional method of graft polymerization can be adopted.

The amount of the unsaturated silane compound to react with the polyolefin resin is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 7 parts by mass, and most preferably 0.5 to 5 parts by mass based on 100 parts by mass of the polyolefin resin. When the amount of the unsaturated silane compound to be reacted is within the above range, the adhesive containing the obtained silane-modified polyolefin-based resin becomes more excellent in adhesive strength.

As the silane-modified polyolefin-based resin, a commercially available one can also be used. Commercially available products include, for example, LINKLON (registered trademark) (manufactured by Mitsubishi Chemical Corporation) and the like. In particular, 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 used.

The modified polyolefin-based resins may be used alone or in combination of two or more.

The number average molecular weight (Mn) of the modified polyolefin-based resin is preferably 10,000-2,000,000, more preferably 20,000-1,500,000, for the reasons of easily obtaining the effect of the present invention. The number average molecular weight (Mn)-based solvent of the modified polyolefin-based resin uses tetrahydrofuran (THF) and performs gel permeation chromatography (GPC) to obtain a standard polystyrene-equivalent value.

Component (B): polyfunctional epoxy compound without aromatic ring The adhesive composition of the present invention is a polyfunctional epoxy compound without aromatic ring containing component (B). Since the adhesive composition of the present invention contains a multifunctional epoxy compound, its cured product has excellent water vapor barrier properties. Furthermore, since the component (B) used in the present invention is a polyfunctional epoxy compound without an aromatic ring, the adhesive composition containing it can provide a cured product with excellent transparency. That is, the polyfunctional epoxy compound which does not have an aromatic ring has higher compatibility with the modified polyolefin resin of (A) component than the polyfunctional epoxy compound which has an aromatic ring. Therefore, by using the polyfunctional epoxy compound as the component (B), an adhesive composition capable of providing a cured product with higher light transmittance and less haze can be obtained. 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 described later, the b* value of the hardened product of the adhesive composition of the present invention is preferably close to 0, so it is more preferable that the molecule does not contain a polyfunctional epoxy compound with a phenoxy structure. The term "phenoxy structure" here refers to the partial structures shown in (a) and (b) below (the same applies hereinafter):

[chemical 1]

In the above formulas (a) and (b), A ¹ represents an unsubstituted (or substituted) aryl group; A ² represents an unsubstituted (or substituted) aryl group. Among the unsubstituted (or substituted) aryl groups, the aryl group includes, for example, phenyl, 1-naphthyl, 2-naphthyl and the like. Among the unsubstituted (or substituent) aryl groups, the aryl groups include, for example: 1,4-phenylene, 1,3-phenylene, 1,2-phenylene, 1,5- Naphthyl, 2,6-naphthyl, etc. Among aryl groups with substituents and aryl groups with substituents, the substituents represent: methyl, isopropyl, tertiary butyl and other alkyl groups with 1 to 6 carbons; methoxy, isopropoxy C1-6 alkoxy group, tertiary butoxy group, etc.; halogen atom such as fluorine atom, chlorine atom, bromine atom, etc.

The so-called "polyfunctional epoxy compound" refers to a compound having two or more epoxy groups in the molecule. (B) The component system can be, for example: 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, Hydrogenated Bisphenol S Diglycidyl Ether, Pentaerythritol Polyglycidyl Ether, 1,6-Hexanediol Diglycidyl Ether, Diglycidyl Hexahydrophthalate, Neopentyl Diglycidyl Ether Alcohol Diglycidyl Ether, Trimethylolpropane Polyglycidyl Ether, 2,2-Bis(3-Epoxypropyl-4-Glycidyloxyphenyl)propane, Dimethyloltricyclodecane Alkane Diglycidyl Ether, Dicyclopentadiene Dimethanol Diglycidyl Ether, etc. The polyfunctional epoxy compound system 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 of the component (B) is preferably 100-3,000, more preferably 200-1,500, for reasons such as the effect of the present invention can be easily obtained.

The epoxy equivalent of the polyfunctional epoxy compound of the component (B) is preferably from 100 g/eq to 500 g/eq, more preferably from 150 g/eq to 300 g/eq. The low outgassing sealing material can be efficiently formed by using the adhesive composition containing the polyfunctional epoxy compound of the component (B) having an epoxy equivalent weight of not less than 100 g/eq and not more than 500 g/eq.

The adhesive composition of the present invention may contain, in addition to the above-mentioned components (A) and (B), an adhesive agent having a softening point of (C) of 80° C. or higher. The adhesive composition containing the component (C) can easily maintain a certain shape, and can form a sheet-shaped adhesive layer more efficiently.

The tackifier of component (C) is provided that the tackifier has a softening point of 80° C. or higher, and the rest are not particularly limited. For example: rosin-based resins such as polymerized rosin, polymerized rosin ester, and rosin derivatives; terpene-based resins such as polyterpene resins, aromatic modified terpene resins and their hydrogenated products, and terpene phenol resins; coumarone-indene Resins; petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins and their hydrogenated products, aliphatic/aromatic copolymer petroleum resins; low molecular weight polymers of styrene or substituted styrene; α-methylstyrene Polymer resin, α-methylstyrene/styrene copolymer resin, styrene monomer/aliphatic monomer copolymer resin, styrene monomer/α-methylstyrene/aliphatic Monomer copolymer resin, styrene monomer monopolymer resin, styrene monomer/aromatic monomer copolymer resin, and other styrene resins. These tackifiers can be used alone or in combination of two or more. Among these, styrene-based resins are preferred, and styrene-based monomer/aliphatic monomer copolymerized resins are more preferred.

Component (C) is a tackifier with a softening point of 80°C or higher. By using a tackifier having a softening point of 80° C. or higher, an adhesive composition excellent in tackiness at high temperatures can be obtained. In addition, workability when forming the adhesive composition into a sheet shape is also improved.

When the adhesive composition of this invention contains (C)component, the content is preferably 1-200 mass parts with respect to 100 mass parts of said (A) components, More preferably, it is 10-150 mass parts. When containing (C)component, if the content of (C)component is too small, it may become difficult to shape an adhesive composition into a sheet shape. On the other hand, when there is too much content of (C)component, there exists a possibility that an adhesive agent layer may become brittle.

The adhesive composition of the present invention may contain an imidazole-based hardening catalyst of the component (D) in addition to the above-mentioned components (A) and (B). By using an adhesive composition containing an imidazole-based curing catalyst, a cured product having excellent adhesiveness even at high temperatures can be easily obtained.

Examples of imidazole-based hardening 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-dimethylimidazole and the like. Among them, 2-ethyl-4-methylimidazole is preferred. These imidazole-based curing catalysts may be used alone or in combination of two or more.

When the adhesive composition of the present invention contains the component (D), the content is preferably 1 to 10 parts by mass, more preferably 2 to 5 parts by mass, based on 100 parts by mass of the above-mentioned component (A). The cured product of the adhesive composition containing the imidazole-based curing catalyst in this range has excellent adhesiveness even at high temperatures.

The adhesive composition of the present invention may contain a silane coupling agent (E) in addition to the above-mentioned (A) and (B) components. By using an adhesive composition containing a silane coupling agent, it is possible to easily obtain a cured product with better adhesive strength under normal temperature and high temperature environments.

As the silane coupling agent, known silane coupling agents can be used. Among them, organosilicon compounds having at least one alkoxysilyl group in the molecule are preferred. Silane coupling agents can include, for example, silicon compounds containing polymerizable unsaturated groups such as ethylene trimethoxysilane, ethylene triethoxysilane, 3-(meth)acryloxypropyl trimethoxysilane; 3-epoxy Silicone with epoxy structure such as propoxypropyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Compounds; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-8-aminooctyltrimethoxy Amino-containing silicon compounds such as silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane; 3-isocyanatopropyltriethyl Oxysilane, 3-mercaptopropyltrimethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, etc. These silane coupling agents may be used alone or in combination of two or more.

When the adhesive composition of the present invention contains a silane coupling agent, its content is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass relative to 100 parts by mass of the above-mentioned component (A).

The adhesive composition of this invention may also contain a solvent. Examples of solvent systems 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-pentane, n-hexane, n- Aliphatic hydrocarbon solvents such as heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane, etc. These solvents may be used alone or in combination of two or more. The solvent content can be appropriately determined in consideration of applicability and the like.

The adhesive composition of the present invention may contain other components within the range not to inhibit the effects of the present invention. The other components include, for example, additives such as ultraviolet 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 composition of the present invention contains these additives, the content can be appropriately determined according to the purpose.

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

When the adhesive composition of the present invention is formed into a thin sheet with a thickness of 10 μm, and then hardened and subjected to color measurement, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 is -2.0 ~+2.0. In the above-mentioned color measurement, the method described below can be used for the method of forming the adhesive composition into a sheet and the method of hardening it.

In the L*a*b* color system, the L* system represents lightness, and the a* and b* systems represent hue and chroma. When a* is positive, it means the color and chroma in the red direction; when a* is negative, it means the color and chroma in the green direction; when b* is positive, it means the color and chroma in the yellow direction , when b* is a negative value, it represents the color and chroma in the blue direction. As the absolute values of a* and b* become smaller, it gradually becomes colorless. The b* value of the hardened product of the adhesive composition of the present invention is -2.0~+2.0, preferably -1.0~+2.0, more preferably 0.0~2.0, and most preferably 0.0~1.0. The cured system of the adhesive composition of the present invention is less deviated in either the yellow direction (+b*) or the blue direction (-b*). The adhesive composition that can provide a cured product with b* in the above range has the advantages of high total light transmittance, low haze value, and very little coloring, and is quite suitable as a sealing material for light-emitting devices such as organic EL elements. In the CIE L*a*b* color system, the b* value can be measured by the method described in the examples.

The b* value of the above cured product is affected by the compound having an aromatic ring (phenoxy structure) contained in the adhesive composition. Therefore, an adhesive composition that can provide a cured product with a b* value of -2.0~+2.0 can be efficiently and easily prepared by not using a compound with an aromatic ring (phenoxy structure) or reducing the amount of use. . The adhesive composition of the present invention preferably does not contain a compound having an aromatic ring (phenoxy structure), or contains a small amount of a compound having an aromatic ring (phenoxy structure) (relative to the entire adhesive composition, depending on the solid 5% by weight or less), more preferably no compound having an aromatic ring (phenoxy structure).

The adhesive composition of the present invention will be formed into a thin sheet with a thickness of 10 μm, and then hardened to become a test piece. When measuring the total light transmittance and haze value, the total light transmittance is preferably more than 85%. , preferably more than 90%. The upper limit of the total light transmittance is not particularly limited, and is usually below 95%. Also, the haze value is preferably at most 1.4%, more preferably at most 1%. The lower limit of the haze value is not particularly limited, and is usually 0.5% or more. The total light transmittance can be measured in accordance with JIS K7361:1997. The haze value can be measured based on JIS K7136:2000.

As mentioned above, the adhesive composition of the present invention uses a modified polyolefin resin as the component (A), and uses a polyfunctional epoxy compound that is highly compatible with the component (A) without an aromatic ring. A polyfunctional epoxy compound is used as (B) component. As a result, the hardened 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 easy to form into a sheet shape, and has excellent colorless transparency. Therefore, the adhesive composition of the present invention is quite 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.

The thickness of the adhesive layer of the adhesive sheet is not particularly limited, and is usually 5-25 μm, preferably 10-20 μm. The adhesive layer whose thickness is within the above range is suitable as a sealing material.

The adhesive sheet of the present invention may also be provided with a release film. The release film functions as a support in the production steps of the adhesive sheet, and functions 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, conventionally known ones can be used. For example, a release layer subjected to a release treatment with a release agent is provided on a base material for a release film. Examples of substrates for release films include paper substrates such as cellophane, coated paper, and high-grade paper; laminated paper in which thermoplastic resins such as polyethylene are laminated on these paper substrates; and polyethylene terephthalate. Plastic films such as diester resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polypropylene resin, polyethylene resin, etc. The release agent system can include, for example, rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins; long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins. wait.

When the inventive adhesive sheet has a release film, the number of release films may be one or two, and usually one (total two) release films are respectively provided on both sides of the adhesive layer. At this time, the two peeling films may be the same or different, but it is preferable that the two peeling films have different peeling forces. Since the peeling force of the two peeling films is different, problems are less likely to occur when the adhesive sheet is used. That is, by setting the peeling forces of the two peeling films differently, the step of tearing the peeling film first can be performed efficiently.

The method for producing the adhesive sheet is not particularly limited. Adhesive sheets can be produced, for example, by casting. The method for producing the adhesive sheet is not particularly limited. Adhesive sheets can be produced, for example, by casting. When producing an adhesive sheet by a casting method, by using a known method, the adhesive composition of the present invention is applied to the release-treated surface of the release film, and the obtained coating film is dried to produce an adhesive with a release film. layer, and then by superimposing another peel-off film on the adhesive layer, an adhesive sheet can be obtained.

The method of coating the adhesive composition includes, for example, spin coating, spray coating, bar coating, knife coating, roll coating, knife coating, die coating, and gravure coating. The drying conditions when drying the coating film can be, for example: a drying temperature of 80-150° C., and a drying time of 30 seconds to 5 minutes. The drying conditions when drying the coating film can be, for example: a drying temperature of 80-150° C., and a drying time of 30 seconds to 5 minutes.

The adhesive layer system of the adhesive sheet of the present invention has thermosetting properties. The 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 thermally hardened state of the adhesive layer of the present invention refers to the state of hardening to the extent that it can be used as a sealant.

The 23°C tearing adhesive strength of the hardened adhesive layer is usually 1~100N/25mm, preferably 10~50N/25mm, and the 85°C tearing adhesive strength is usually 1~100N/25mm, relatively The best is 5~50N/25mm. The tear adhesion strength at 23°C is based on JIS Z0237: 2009, in the environment of temperature 23°C, relative humidity 50%, and temperature 85°C (uncontrolled humidity), the peeling test is carried out according to the peeling angle of 180°, respectively. measurable. The tear adhesion strength at 23°C is based on JIS Z0237: 2009, in the environment of temperature 23°C, relative humidity 50%, and temperature 85°C (uncontrolled humidity), the peeling test is carried out according to the peeling angle of 180°, respectively. measurable. The water vapor transmission rate of the hardened adhesive layer is usually 0.1~200g‧m ^-2 ‧day ^-1 , preferably 1~150g‧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, the transmission rate measuring machine “L80-5000” manufactured by LYSSY Co., Ltd.).

As mentioned 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 suitable for sealing, for example, organic EL elements, organic EL display elements, liquid crystal display elements, solar cell elements, and the like.

3) Sealed body The sealed object of the sealing system of the present invention is sealed using the adhesive sheet of the present invention. The sealing system of the present invention includes, for example: a substrate, an element (to-be-sealed object) formed on the substrate, and a sealing material for sealing the element. The above-mentioned sealing material can be derived from, for example, the adhesive layer of the adhesive sheet of the present invention. Those (the hardened product of the adhesive layer).

The substrate is not particularly limited, and various substrate materials can be used. It is particularly preferred to use a substrate material with high visible light transmittance. Also, it is preferable to use a material that has a high barrier performance against moisture and gas that may permeate from the outside of the device, and is excellent in solvent resistance and weather resistance. Specific systems include, for example: transparent inorganic materials such as quartz and glass; polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyethylene, polypropylene, polyphenylene sulfide, Transparent plastics such as polyvinylidene fluoride, cellulose acetate, brominated phenoxy, aramids, polyimides, polystyrenes, polyarylates, polysulfones, polyolefins, etc.; the aforementioned gas barrier thin films, etc. The thickness of the substrate is not particularly limited, and can be properly selected after considering the light transmittance and the performance of blocking the inside and outside of the element.

The sealed object system may, for example, be an organic EL element, an organic EL display element, a liquid crystal display element, or a solar cell element.

The method for producing the sealing body of the present invention is not particularly limited. For example, after superimposing the adhesive layer of the adhesive sheet of the present invention on the object to be sealed, heating is applied to make the adhesive layer of the adhesive sheet adhere to the object to be sealed, and then the adhesive layer is hardened to produce the present invention. Invented seals.

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

The object to be sealed in the sealing system of the present invention is sealed by using the adhesive sheet of the present invention. Therefore, the sealing system of the present invention can maintain the performance of the sealed object for a long time. [Example]

Hereinafter, examples are given to describe the present invention in more detail. However, the present invention is not limited by the following examples. The "parts" and "%" in each example are quality standards unless otherwise stated.

[Example 1] 100 parts of acid-modified polyolefin resin (acid-modified α-olefin polymer, manufactured by Mitsui Chemicals, trade name: UNISTOLEH-200, number average molecular weight: 47,000), polyfunctional epoxy compound (1) 25 parts of (hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, trade name: YX8000, epoxy equivalent: 205 g/eq), imidazole-based hardening catalyst (manufactured by Shikoku Chemicals Co., Ltd., trade name: Curezol) 2E4MZ, 0.25 parts of 2-ethyl-4-methylimidazole), and 0.1 part of silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM6803) were dissolved in methyl ethyl ketone to prepare an adhesive with a solid concentration of 20%. Composition 1. This adhesive composition 1 was coated on the release-treated surface of a release film (manufactured by Lintec Corporation, trade name: SP-PET382150), and the obtained coating film was dried at 100°C for 2 minutes to form an adhesive film with a thickness of 10 μm. The agent layer was bonded to the surface of another release film (manufactured by Lintec, trade name: SP-PET381031) on the release treatment surface 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 type epoxy resin, manufactured by Mitsubishi Chemical Corporation, Except for product name: YX8034, epoxy equivalent: 270 g/eq), the adhesive composition 2 was prepared in the same manner as in Example 1, and the adhesive sheet 2 was obtained using it.

[Example 3] In Example 1, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (3) (manufactured by ADEKA Corporation, trade name: EP-4088L, dicyclopentanyl Adhesive composition 3 was prepared in the same manner as in Example 1 except for diene dimethanol diglycidyl ether and epoxy equivalent: 165 g/eq), and an adhesive sheet 3 was obtained using it.

[Example 4] 100 parts of acid-modified polyolefin resin (α-olefin polymer, manufactured by Mitsui Chemicals, trade name: UNISTOLEH-200, number average molecular weight: 47,000), 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 Corporation, trade name: FTR6100) 50 parts, imidazole-based hardening catalyst (manufactured by Shikoku Chemicals Co., Ltd., trade name: Curezol 2E4MZ, 2-ethyl-4-methylimidazole) 1 part, and silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name : KBM6803) 0.1 part, dissolved in methyl ethyl ketone, and prepared adhesive composition 4 with a solid content concentration of 30%. 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] Except in Example 4, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (2) (hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation, Except for the product name: YX8034), the adhesive composition 5 was prepared in the same manner as in Example 4, and an adhesive sheet 5 was obtained using it.

[Example 6] Except 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, Except product name: YX8040, epoxy equivalent: 1100g/eq), the adhesive agent composition 6 was prepared in the same manner as in Example 4, and the adhesive sheet 6 was obtained using it.

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

[Comparative Example 1] Except in Example 4, instead of the polyfunctional epoxy compound (1), a polyfunctional epoxy compound (5) (non-hydrogenated bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Co., Ltd. , trade name: jER828, epoxy equivalent: 190g/eq), and the rest were prepared in the same manner as in Example 1. Adhesive composition 8 was used to obtain adhesive sheet 8.

For the adhesive sheets 1-8 obtained in Examples 1-7 and Comparative Example 1, the following tests were performed. The results are shown in Table 1. [Measurement of Total Light Transmittance and Haze] One peeling film was torn off to remove the adhesive sheet obtained in the example or comparative example to expose the adhesive layer. Place the adhesive sheet on the soda-lime glass in such a way that the exposed adhesive layer faces the soda-lime glass, and then use a pressing machine to bond them together at 23°C. After tearing and removing the other peeling film, the adhesive layer was hardened by heating at 100°C for 2 hours to obtain a test piece. About the obtained test piece, the total light transmittance and haze were measured using the total light transmittance measuring apparatus (made by Nippon Denshoku Kogyo Co., Ltd., product name: NDH-5000).

〔Color measurement〕 Prepare the same test pieces as those used in the measurement of total light transmittance and haze. With respect to the obtained test piece, the color value b* specified by the CIE1976L*a*b* colorimetric system was measured using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3200) according to JIS Z 8729-1994.

[Table 1]

The following matters can be obtained from Table 1. The cured products of the adhesive layers of the adhesive sheets 1-7 obtained in Examples 1-7 have high total light transmittance and low haze value. And, the b* value is -2.0~+2.0. On the other hand, the hardened product of the adhesive layer of the adhesive sheet 8 obtained in Comparative Example 1 had a large haze value and poor transparency.

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Claims (10)

An adhesive sheet is an adhesive sheet composed of an adhesive layer and two peeling films, wherein the peeling film is one on both sides of the adhesive layer, and the adhesive layer uses the following adhesive composition 1 (Adhesive composition 1) is an adhesive composition comprising the following (A) component, (B) component, and (D) component, and the above-mentioned adhesive layer has thermosetting properties, It is characterized in that: when the adhesive composition is formed into a thin sheet with a thickness of 10 μm , and then hardened to measure the color, the b* value of the CIE L*a*b* color system specified in JIS Z 8729-1994 System -2.0~+2.0; (A) component: acid modified polyolefin resin, obtained by reacting polyolefin resin with unsaturated carboxylic acid or unsaturated carboxylic acid anhydride, unsaturated carboxylic acid or unsaturated carboxylic anhydride Quantity, with respect to polyolefin resin 100 mass parts, be 0.2～3 mass parts; (B) component: the polyfunctional group epoxy compound that does not have aromatic ring, be selected from 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, hydrogenated bisphenol S diglycidyl ether, pentaerythritol polyglycidyl ether , 1,6-Hexanediol Diglycidyl Ether, Diglycidyl Hexahydrophthalate, Neopentyl Glycol Diglycidyl Ether, Trimethylolpropane Polyglycidyl Ether, Dimethylol One or more of the group consisting of tricyclodecane diglycidyl ether and dicyclopentadiene dimethanol diglycidyl ether; (D) component: an imidazole-based hardening catalyst. Such as the adhesive sheet of item 1 of the scope of the patent application, wherein, relative to the above-mentioned (A) component 100 mass parts, the content of the said (B) component is 1-200 mass parts. Such as the adhesive sheet of item 1 of the scope of the patent application, which further contains the following (C) component: (C) component: a tackifier with a softening point of 80°C or higher. Such as the adhesive sheet of claim 3, wherein the content of the above-mentioned (C) component is 1 to 200 parts by mass relative to 100 parts by mass of the above-mentioned (A) component. Such as the adhesive sheet of claim 1, wherein the content of the above-mentioned (D) component is 1 to 10 parts by mass relative to 100 parts by mass of the above-mentioned (B) component. Such as the adhesive sheet of item 1 of the scope of the patent application, which further contains the following (E) component: (E) component: silane coupling compound. Such as the adhesive sheet of claim 6, wherein the content of the above-mentioned component (E) is 0.01 to 10 parts by mass relative to 100 parts by mass of the above-mentioned component (A). For example, the adhesive sheet of item 1 of the scope of application, wherein the thickness of the adhesive layer is 5-25 μm. A sealing body is sealed by using the adhesive sheet in any one of items 1 to 8 of the patent application scope. The sealed body according to claim 9 of the patent application, wherein the above-mentioned sealed object is an organic EL element, an organic EL display element, a liquid crystal display element, or a solar cell element.