JP2022145062A - Adhesive composition and adhesive sheet - Google Patents

Abstract

To provide an adhesive composition capable of forming an optical adhesive sheet which has excellent adhesive force while maintaining high transparency and also has excellent heat-resistant adhesive force, and to provide an optical adhesive sheet.SOLUTION: The adhesive composition of the present invention contains at least a (meth)acrylic polymer having a functional group, and zeolite particles. The zeolite particles have an average primary particle diameter of 20-150 nm. The content of the zeolite particles is 0.01-5 pts.mass based on 100 pts.mass of the (meth)acrylic polymer.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an adhesive composition and an adhesive sheet.

2. Description of the Related Art Conventionally, display devices such as liquid crystal displays (LCDs) and input devices such as touch panels used in combination with display devices have been widely used. In the manufacture of these display devices and input devices, transparent adhesive sheets are used for bonding optical members, and transparent adhesive sheets are also used for bonding display devices and input devices. .

In order to improve the performance of such pressure-sensitive adhesive sheets, pressure-sensitive adhesive compositions that serve as raw materials for producing pressure-sensitive adhesive sheets have also been extensively studied. For example, various polymerization methods are used to obtain various pressure-sensitive adhesive compositions. A method is also proposed. For example, Patent Document 1 discloses a water-dispersible pressure-sensitive adhesive composition containing an acrylic copolymer, a silane coupling agent, and inorganic particles such as silica. It is disclosed to improve the optical properties and durability of the pressure-sensitive adhesive sheet.

JP 2012-111871 A

However, in the technique disclosed in Patent Document 1, the desired adhesive strength and cohesive strength cannot be exhibited unless the amount of inorganic particles added is relatively large, which impairs the transparency of the adhesive sheet itself. The problem was that it was easy. Conversely, in the technique disclosed in Patent Document 1, the transparency cannot be maintained unless the thickness is reduced (for example, 20 μm), which limits the thickness. Further, Patent Document 1 does not specifically evaluate the adhesive strength, but only discloses relative evaluation such as durability evaluation.

The present invention has been made in view of the above, and a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive sheet having excellent adhesive strength while maintaining high transparency and having excellent heat-resistant adhesive strength, and An object of the present invention is to provide an optical pressure-sensitive adhesive sheet.

As a result of intensive studies aimed at achieving the above object, the present inventors found that the above object can be achieved by using a (meth)acrylic polymer having a functional group and zeolite particles in a predetermined ratio. The present invention has been completed.

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
containing at least a (meth)acrylic polymer having a functional group and zeolite particles,
The zeolite particles have an average primary particle size of 20 to 150 nm,
The pressure-sensitive adhesive composition, wherein the content of the zeolite particles is 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer.
Item 2
Item 1. The pressure-sensitive adhesive composition according to Item 1, further comprising a silane coupling agent.
Item 3
Item 3. The pressure-sensitive adhesive composition according to Item 1 or 2, further comprising at least one of a cross-linking agent and a polyfunctional monomer.
Item 4
A pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive composition according to any one of Items 1 to 3,
A pressure-sensitive adhesive sheet having a haze of less than 1% when the pressure-sensitive adhesive has a thickness of 175 μm.

The pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive sheet that maintains high transparency, has excellent adhesive strength, and is also excellent in heat-resistant adhesive strength. Moreover, since the pressure-sensitive adhesive sheet of the present invention is formed using the pressure-sensitive adhesive composition, it has excellent adhesive strength while maintaining high transparency, and is also excellent in heat-resistant adhesive strength.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "contain" and "include" include the concepts of "contain", "include", "substantially consist of" and "consist only of".

1. Adhesive Composition The adhesive composition of the present invention contains at least a (meth)acrylic polymer having a functional group and zeolite particles. The zeolite particles have an average primary particle diameter of 20 to 150 nm, and the content of the zeolite particles is 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer. By using such a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer can be formed, and a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer can be obtained. The pressure-sensitive adhesive sheet thus formed has excellent adhesive strength while maintaining high transparency, and is also excellent in heat-resistant adhesive strength.

In this specification, "(meth)acryl" means "acryl" or "methacryl", and "(meth)acrylate" means "acrylate" or "methacrylate".

A (meth)acrylic polymer having a functional group is, for example, a polymer having a structure in which a functional group is bonded (particularly covalently bonded) to a (meth)acrylic copolymer skeleton.

In the (meth)acrylic polymer having a functional group, examples of the types of functional groups include groups exhibiting cross-linking reactivity, specifically hydroxyl groups, carboxy groups, amino groups, amide groups, epoxy groups, and thiols. groups, isocyanate groups, and the like. Among them, the functional group is preferably a hydroxyl group. In this case, the (meth)acrylic polymer having the functional group easily forms a crosslinked structure. A (meth)acrylic polymer having functional groups can also be referred to as a crosslinkable (meth)acrylic polymer.

As the (meth)acrylic polymer having a functional group, for example, known crosslinkable (meth)acrylic polymers used in adhesive sheets can be widely applied. Examples of the (meth)acrylic polymer having a functional group include a (meth)acrylic copolymer containing a monomer unit having the functional group and a monomer unit having no functional group. can. When the (meth)acrylic polymer having a functional group is the (meth)acrylic copolymer, by copolymerizing a monomer containing the monomer A having the functional group and the monomer B having no functional group , a (meth)acrylic polymer with functional groups can be obtained.

Examples of the monomer A include hydroxyl group-containing (meth)acrylic monomers and carboxy group-containing (meth)acrylic monomers.

The type of hydroxyl group-containing (meth)acrylic monomer is not particularly limited as long as it has one or more hydroxyl groups in its molecule. For example, hydroxyl group-containing (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 2- Hydroxybutyl (meth) acrylate, 2-hydroxy 3-phenoxypropyl (meth) acrylate, 2,2-dimethyl 2-hydroxyethyl (meth) acrylate, 3-chloro 2-hydroxypropyl (meth) acrylate, 2-hydroxy 3- hydroxyalkyl (meth)acrylates such as phenoxypropyl (meth)acrylate and 8-hydroxyoctyl (meth)acrylate; hydroxyalkyl (meth)acrylamides such as N-hydroxypropyl (meth)acrylamide;

Among these, the hydroxyl group-containing (meth)acrylic monomer is one or more selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. is preferred. In this case, it is easy to obtain a PSA sheet with high transparency and excellent heat-resistant adhesive strength.

The type of carboxy group-containing (meth)acrylic monomer is not particularly limited as long as it has one or more carboxy groups in the molecule. For example, carboxy group-containing (meth)acrylic monomers include (meth)acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, citraconic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-( meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, carboxylethyl (meth)acrylate, carboxypolycaprolactone mono(meth)acrylate and the like.

Monomer A may also be a (meth)acrylic monomer having at least one functional group such as an amino group, an amide group, an epoxy group, a thiol group and an isocyanate group.

Monomer A is preferably a hydroxyl group-containing (meth)acrylic monomer in that a pressure-sensitive adhesive sheet having high transparency and excellent heat-resistant adhesive strength can be easily obtained. Further, the monomer A may be a mixture of a hydroxyl group-containing (meth)acrylic monomer and a carboxyl group-containing (meth)acrylic monomer. In this case, the hydroxyl group-containing (meth)acrylic monomer and the carboxyl group-containing (meth)acrylic monomer The content ratio of and is not particularly limited, and the effects of the present invention can be exhibited at any ratio.

Examples of the monomer B include (meth)acrylates having linear, branched or cyclic alkyl groups, or (meth)acrylates having an aromatic ring. When the (meth)acrylate has a linear, branched or cyclic alkyl group, the number of carbon atoms can be, for example, 1-20, preferably 1-10. When the (meth)acrylate has an aromatic ring, its carbon number can be, for example, 5-20, preferably 6-10. Specific examples of monomer B include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, isooctyl (meth) acrylate, 2- Ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate and the like can be mentioned.

Among these, monomer B is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isopropyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl Alkyl (meth)acrylates such as (meth)acrylates are preferred. In this case, it is easy to obtain a PSA sheet with high transparency and excellent heat-resistant adhesive strength.

Both the monomer A and the monomer B may be used singly or as a mixture of two or more.

Monomers for producing a (meth)acrylic polymer having a functional group can include monomers other than monomer A and monomer B, for example, a wide variety of compounds capable of polymerizing with monomer A and monomer B are listed. be able to. Specific examples include vinyl acetate and styrene. The content of the monomers A and B contained in the monomers for producing the (meth)acrylic polymer having a functional group is 50% by mass or more, preferably 80% by mass or more, and 90% by mass or more. More preferably, it is 99% by mass or more, and it may be 100% by mass.

The ratio of the monomer A and the monomer B is not particularly limited, and can be appropriately set according to the structure of the (meth)acrylic polymer having the desired functional group. For example, the content of the monomer A is 0.5 to 60 parts by mass per 100 parts by mass of the total amount of the monomer A and the monomer B in that a pressure-sensitive adhesive sheet having high transparency and excellent heat-resistant adhesive strength can be easily obtained. It is preferably 1 to 55 parts by mass.

The ratio of the monomer units derived from the monomer A and the monomer units derived from the monomer A in the (meth)acrylic polymer having a functional group is used in the production of the (meth)acrylic polymer having a functional group. corresponds to the usage ratio (mass ratio) of monomer A and monomer B.

A (meth)acrylic polymer having a functional group can be produced, for example, by polymerizing monomers including monomer A and monomer B by a known polymerization method. As this polymerization method, for example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like can be employed.

In polymerizing the (meth)acrylic polymer having a functional group, a solvent can be used as necessary. The type of solvent is not particularly limited, and for example, a wide range of known organic solvents used in polymerization can be used. Examples thereof include ester compounds such as ethyl acetate and butyl acetate; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as hexane; and aromatic compounds such as toluene, xylene and benzene. The amount of the solvent used in the polymerization reaction is not particularly limited.

Further, in polymerizing the (meth)acrylic polymer having a functional group, a polymerization initiator can be used. For example, a wide range of known polymerization initiators used in general polymerization can be used. . Examples of polymerization initiators include azobisisobutyronitrile, 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 1,1′-azobis(cyclohexanecarbonitrile), di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, photopolymerization initiators (Irgacure or Omnilad (registered trademark) series, etc.) and the like. The amount of the polymerization initiator to be used is not particularly limited, and can be appropriately adjusted according to, for example, the target molecular weight. For example, 0.01 to 5 parts by mass of the polymerization initiator can be used per 100 parts by mass of the total amount of the monomers A and B.

In addition, a chain transfer agent, a polymerization accelerator, etc. may be used in polymerizing the (meth)acrylic polymer having a functional group.

The polymerization time and polymerization temperature are also not limited, and can be appropriately set according to the type, amount, and polymerization reactivity of the monomers A and B to be used. For example, the polymerization reaction can be carried out at 20 to 100° C. for 1 to 24 hours. Polymerization can be appropriately carried out under an inert gas atmosphere such as nitrogen.

The weight average molecular weight of the (meth)acrylic polymer having a functional group is not particularly limited. 10,000 is more preferable.

In addition, the weight average molecular weight as used in the field of this invention is the polystyrene conversion weight average molecular weight measured by the gel permeation chromatography (GPC) method. The GPC apparatus used in the GPC method is not particularly limited, and commercially available GPC measuring instruments such as LC-2000Plus series manufactured by JASCO Corporation, and RI-2031Plus and UV-2075Plus as detectors can be used. In this case, for example, a GPC column formed by connecting four columns of "Shodex KF801", "Shodex KF803L", "Shodex KF800L" and "Shodex KF800D" manufactured by Showa Denko KK is used. The column temperature can be 40°C. Tetrahydrofuran is used as the eluent, and the measurement is performed at a flow rate of 1.0 ml/min. Normally, a standard polystyrene is used to prepare a calibration curve, and the weight average molecular weight (Mw) can be obtained by polystyrene conversion.

The (meth)acrylic polymer with functional groups may be a random copolymer, or the (meth)acrylic polymer with functional groups may have other structures such as block polymers.

(zeolite particles)
The adhesive composition of the present invention contains at least zeolite particles. When the zeolite particles are contained in the pressure-sensitive adhesive composition, the cohesive strength of the pressure-sensitive adhesive layer is increased, and the heat-resistant adhesive strength is excellent. Moreover, since the content of zeolite particles may be smaller than that of conventional inorganic substances, etc., the adhesive sheet has high transparency, and high transparency can be imparted even if the adhesive sheet is thick.

The zeolite particles have an average primary particle size of 20 to 150 nm, and the type thereof is not particularly limited as long as the main component is zeolite. The average primary particle size as used herein refers to a value measured by scanning electron microscope observation (SEM observation). Specifically, 50 particles are randomly selected by direct observation by SEM observation, the equivalent circle diameters of these particles are measured, and the arithmetic average value is obtained. If the manufacturer-guaranteed value or the manufacturer-measured value of the average primary particle size of the zeolite particles is known, that value can be used as the average primary particle size of the zeolite particles.

The average primary particle size of the zeolite particles is preferably 5 nm or more, more preferably 10 nm or more. Also, the average primary particle size of the zeolite particles is preferably 200 nm or less, more preferably 150 nm or less.

The zeolite particles may be formed of zeolite alone, or may contain components other than zeolite as long as the effects of the present invention are not impaired. It should be noted that the phrase "the zeolite particles are formed only of zeolite" does not exclude other components that are unavoidably contained in the zeolite particles.

The type of zeolite is not particularly limited, and for example, a wide range of known zeolites can be used.

Zeolite particles can be obtained, for example, by a known production method, or can be obtained from commercial products.

(Adhesive composition)
In the pressure-sensitive adhesive composition of the present invention, the content of zeolite particles is 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer having a functional group. As a result, it is possible to form a pressure-sensitive adhesive sheet that maintains high transparency, has excellent adhesive strength, and is also excellent in heat-resistant adhesive strength. If the content of the zeolite particles is less than 0.01 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer having a functional group, the problem of insufficient adhesion occurs. Moreover, if the content of the zeolite particles exceeds 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer having a functional group, the problem of loss of transparency also occurs.

The content of the zeolite particles is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer having a functional group. The content of the zeolite particles is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and 2 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer having a functional group. is particularly preferred.

The pressure-sensitive adhesive composition of the present invention can contain other components in addition to the (meth)acrylic polymer having functional groups and zeolite particles.

For example, the adhesive composition of the present invention may further contain a silane coupling agent. When the pressure-sensitive adhesive composition of the present invention contains a silane coupling agent, the presence of the silane coupling agent facilitates adhesion between the zeolite particles and the polymer component. As a result, the pressure-sensitive adhesive sheet obtained has improved adhesive strength. Easy to use and more transparent.

The type of silane coupling agent is not particularly limited, and for example, a wide range of known compounds can be used. Silane coupling agents include, for example, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldialkoxysilane, γ- Aminopropyltriethoxysilane, γ-Aminopropyltrimethoxysilane, γ-Glycidoxypropyltriacoxysilane, γ-Methacryloxypropyltrialkoxysilane, γ-Chloropropyltrialkoxysilane, γ-Methacryloxypropyldialkoxysilane , γ-mercaptopropyltrialkoxysilane, vinyltrialkoxysilane, and the like. The silane coupling agent may also be an oligomer of various alkoxysiloxanes. All of these silane coupling agents are commercially available.

When the pressure-sensitive adhesive composition of the present invention contains a silane coupling agent, its content can be 0.1 to 5 parts by mass per 100 parts by mass of the (meth)acrylic polymer having a functional group. Silane coupling agents may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition of the present invention may further contain at least one of a cross-linking agent and a polyfunctional monomer. When the pressure-sensitive adhesive composition of the present invention contains a cross-linking agent, the (meth)acrylic polymer having a functional group can form a cross-linked structure, thereby further improving the pressure-sensitive adhesive strength of the resulting pressure-sensitive adhesive sheet. . Further, when the pressure-sensitive adhesive composition of the present invention contains a polyfunctional monomer, the polymer component in the pressure-sensitive adhesive layer forms a crosslinked structure when the pressure-sensitive adhesive sheet is formed by irradiation with active energy rays such as UV rays as described later. Therefore, the adhesive strength of the obtained adhesive sheet can be further improved. When the pressure-sensitive adhesive composition contains a polyfunctional monomer, it also preferably contains a photopolymerization initiator described later. When the pressure-sensitive adhesive composition of the present invention contains both a cross-linking agent and a polyfunctional monomer, the heat-resistant pressure-sensitive adhesive strength tends to be improved.

Cross-linking agents include, for example, a wide range of components for promoting cross-linking of (meth)acrylic polymers having functional groups. In particular, cross-linking agents can broadly include components that can react with functional groups in a (meth)acrylic polymer having functional groups.

Examples of such cross-linking agents include widely known cross-linking agents such as isocyanate cross-linking agents and epoxy cross-linking agents.

The type of isocyanate cross-linking agent is not particularly limited, and a wide range of known compounds can be used. Examples of isocyanate cross-linking agents include polyisocyanates such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and xylylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate; and aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4,4′-diphenylmethane diisocyanate. An isocyanate crosslinking agent can be used individually or in mixture of 2 or more different types. Moreover, it is more preferable to use trifunctional derivatives such as adducts, nurates, and burettes obtained from the above diisocyanates as isocyanate cross-linking agents.

The type of epoxy cross-linking agent is not particularly limited, and a wide range of known compounds can be used. Examples of epoxy crosslinking agents include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol. Diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexanone, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl Ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like.

When the pressure-sensitive adhesive composition of the present invention contains a cross-linking agent, its content is not particularly limited, for example, 0.01 to 5 parts by mass per 100 parts by mass of the (meth)acrylic polymer having a functional group can be used. can. In this case, the adhesive sheet tends to have high adhesive strength. The content of the cross-linking agent is preferably 0.05 to 1 part by mass per 100 parts by mass of the (meth)acrylic polymer having a functional group. The cross-linking agents may be used alone or in combination of two or more.

Examples of polyfunctional monomers include compounds having two or more polymerizable double bonds in the molecule. When the pressure-sensitive adhesive composition of the present invention contains a polyfunctional monomer, the polymer component in the pressure-sensitive adhesive layer can form a crosslinked structure by curing the pressure-sensitive adhesive composition with UV irradiation. , the adhesive sheet tends to have excellent adhesion. Polyfunctional monomers can include, for example, a wide range of known polyfunctional monomers used to obtain pressure-sensitive adhesive sheets.

The number of polymerizable double bonds in the polyfunctional monomer is 2 or more, preferably 2 or more and less than 5, more preferably 2 or more and less than 4.

Polyfunctional monomers include, for example, bifunctional monomers (monomers having two polymerizable double bonds) such as polyethylene glycol diacrylate, polypropylene diacrylate, alkyl diacrylate, polytetramethylene glycol diacrylate, Mention may be made of acrylates, polypropylene glycol diacrylate, dioxane diacrylate, tricyclodecanol diacrylate, fluorenediacrylate. In addition, as polyfunctional monomers, tri- or more functional monomers such as alkoxylated trimethylolpropane triacrylate, alkoxylated glycerin triacrylate, caprolactone-modified isocyanurate triacrylate, pentaerythritol acrylate, alkoxylated pentaerythritol acrylate, (Alkoxylated) pentaerythritol acrylate, (alkoxylated) ditrimethylolpropane acrylate, (alkoxylated) dipentaerythritol acrylate, (ethoxylated) polyglycerin acrylate, and the like.

The polyfunctional monomer is preferably a polyfunctional monomer having an alkylene glycol group in one molecule. In this case, the number of alkylene glycol groups in one molecule is preferably 1-20. Examples of such polyfunctional monomers include polyethylene glycol diacrylate, trimethylolpropane propylene oxide-modified triacrylate, and the like.

A commercial item can be used for a polyfunctional monomer, for example. Commercially available products include NK Ester series "A-200" (polyethylene glycol #200 diacrylate), which is a bifunctional polyethylene glycol acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., and trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate), trifunctional monomer M321 (trimethylolpropane propylene oxide-modified triacrylate), bifunctional monomer M211B (bisphenol A EO-modified diacrylate) manufactured by Toagosei Co., Ltd., and the like.

The polyfunctional monomer may have a bisphenol skeleton in one molecule. By using a polyfunctional monomer having a bisphenol skeleton in one molecule, the hardness of the pressure-sensitive adhesive layer can be increased more effectively, and the workability of the pressure-sensitive adhesive sheet can be easily improved. Examples of such polyfunctional monomers include bisphenol A diglycidyl ether diacrylate, propoxylated bisphenol A diacrylate, and bisphenol F diglycidyl ether diacrylate.

When the pressure-sensitive adhesive composition of the present invention contains a polyfunctional monomer, the content is not particularly limited, for example, 0.01 to 20 parts by weight per 100 parts by weight of the (meth)acrylic polymer having a functional group is used. can do. In this case, the adhesive sheet tends to have high adhesive strength. The content of the polyfunctional monomer is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic polymer having a functional group. Polyfunctional monomers may be used alone or in combination of two or more.

Polymerization of polyfunctional monomers proceeds in the presence of, for example, a photopolymerization initiator. Examples of photopolymerization initiators include a wide range of known photopolymerization initiators, and specific examples include acetophenone-based initiators, benzoin ether-based initiators, benzophenone-based initiators, hydroxyalkylphenone-based initiators, and thioxanthone. system initiators, amine-based initiators, acylphosphine oxide-based initiators, and the like.

Specific examples of acetophenone initiators include diethoxyacetophenone, benzyldimethylketal, oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylpropanone], 2,2-dimethoxy-2 -phenylacetophenone, (1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropanone, etc. Specific examples of benzoin ether initiators include benzoin, benzoin methyl ether, and the like. be done.

Specific examples of benzophenone-based initiators include benzophenone and methyl o-benzoylbenzoate. Specific examples of acylphosphine oxide initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

Specific examples of hydroxyalkylphenone-based initiators include 1-hydroxy-cyclohexyl-phenyl-ketone and the like. Specific examples of thioxanthone-based initiators include 2-isopropylthioxanthone and 2,4-dimethylthioxanthone. Specific examples of amine-based initiators include triethanolamine and ethyl 4-dimethylbenzoate.

Specific examples of acylphosphine oxide initiators include phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide and the like.

Other photopolymerization initiators include, for example, 2,2-dimethoxy-2-phenylacetophenone, 1-[4-(2-hydroxyethoxyl)-phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-( Alkylphenone photopolymerization initiators such as 4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1-propanone, intramolecular hydrogen abstraction such as methyl benzoylformate and 4-methylbenzophenone In addition to type photopolymerization initiators, oxime ester photopolymerization initiators, cationic photopolymerization initiators, and the like can be used.

When the adhesive composition of the present invention contains a photopolymerization initiator, the content is not particularly limited, for example, 0.05 to 10 parts by weight per 100 parts by weight of the (meth)acrylic polymer having a functional group is used. and more preferably 0.1 to 5 parts by mass. A photoinitiator may be used individually by 1 type, or may use 2 or more types together.

The pressure-sensitive adhesive composition of the present invention can further contain a polymerizable monomer M, if necessary. Such a polymerizable monomer M is a monomer other than the polyfunctional monomer, and is, for example, a monofunctional polymerizable monomer.

The type of the polymerizable monomer M is not particularly limited, and examples thereof include the same types of monomers as the above-described monomers A and B, and other monomers such as vinyl acetate and styrene. When the pressure-sensitive adhesive composition of the present invention contains a polymerizable monomer M, the polymerizable monomer M forms, for example, a (meth)acrylic polymer having a functional group contained in the pressure-sensitive adhesive composition. (eg, monomer A and monomer B). When two or more kinds of monomers are used, the composition ratio thereof can be the same as the ratio of the monomers for forming the functional group-containing (meth)acrylic polymer contained in the pressure-sensitive adhesive composition.

When the adhesive composition of the present invention contains the polymerizable monomer M, the content is not particularly limited, for example, 5 to 95 parts by weight per 100 parts by weight of the (meth)acrylic polymer having a functional group is used. and more preferably 10 to 90 parts by mass.

The pressure-sensitive adhesive composition of the present invention can contain a solvent from the viewpoint of improving coatability. Examples of solvents include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichlorethylene, tetrachloroethylene, and dichloropropane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol and diacetone alcohol; Ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone; Methyl acetate , Esters such as ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, and ethyl butyrate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Polyols such as glycol monomethyl ether acetate and derivatives thereof are included.

When the pressure-sensitive adhesive composition contains a solvent, its content is not particularly limited, for example, it can be 25 to 500 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer having a functional group, and 30 to 400 parts by mass. Parts by mass are more preferable. Also, the content of the solvent is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, relative to the total mass of the pressure-sensitive adhesive composition. One type of solvent may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

In addition, when the pressure-sensitive adhesive composition of the present invention contains the polymerizable monomer M, the polymerizable monomer M can also serve as a solvent.

The pressure-sensitive adhesive composition can contain various additives for pressure-sensitive adhesives other than those described above as long as the effects of the present invention are not impaired. Such additives can be selected from, for example, plasticizers, antioxidants, metal corrosion inhibitors, tackifiers, ultraviolet absorbers, light stabilizers such as hindered amine compounds, and the like, as required. Dyes and pigments may also be added for the purpose of coloring.

As described above, the pressure-sensitive adhesive composition of the present invention contains at least a (meth)acrylic polymer having a functional group, zeolite particles, and optionally a silane coupling agent, a cross-linking agent, a polyfunctional monomer At least one selected from the group consisting of a polymer, a photopolymerization initiator, a polymerizable monomer M, a solvent and other various additives can be included.

As one aspect, the pressure-sensitive adhesive composition of the present invention contains at least a (meth)acrylic polymer having a functional group, zeolite particles and a cross-linking agent, and may contain a solvent as necessary. In this aspect, the pressure-sensitive adhesive composition may be free of polyfunctional monomers, photopolymerization initiators and polymerizable monomers M. In another aspect, the pressure-sensitive adhesive composition of the present invention contains at least a (meth)acrylic polymer having a functional group, zeolite particles, a polyfunctional monomer, a photopolymerization initiator and a polymerizable monomer M. be able to. In this aspect, the pressure-sensitive adhesive composition may not contain a cross-linking agent.

The method for preparing the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, a (meth)acrylic polymer having a pre-synthesized functional group, zeolite particles, and optionally other components (e.g., the cross-linking agent, polyfunctional monomer, photopolymerization initiator, polymerizable monomer The adhesive composition can be prepared by mixing at least one selected from the group consisting of polymer M, solvent and other various additives) in a predetermined ratio. In this case, the (meth)acrylic polymer having functional groups can be used in the form of a solution or dispersion. When the (meth)acrylic polymer having a functional group is a solution or dispersion, the solution or dispersion may contain the solvent, and may contain the polymerizable monomer M instead of the solvent or together with the solvent. can. The solution or dispersion of the (meth)acrylic polymer having a functional group can have a solid content concentration of, for example, 1 to 50% by mass.

(Adhesive layer)
A pressure-sensitive adhesive layer can be formed by using the pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive layer can be formed by curing the pressure-sensitive adhesive composition, that is, the pressure-sensitive adhesive layer is formed from the cured product of the pressure-sensitive adhesive composition of the present invention. The method for forming the pressure-sensitive adhesive layer is not particularly limited, and for example, the same method as for the known pressure-sensitive adhesive layer can be adopted.

Specifically, a method (hereinafter abbreviated as "Method A") comprising a step of applying a pressure-sensitive adhesive composition on a substrate to form a coating film, and a step of heat-treating the coating film, An adhesive layer can be formed. Alternatively, a method (hereinafter abbreviated as "Method B") comprising a step of applying the pressure-sensitive adhesive composition on a substrate to form a coating film, and a step of irradiating the coating film with an active energy ray, A pressure-sensitive adhesive layer can be formed by curing the pressure-sensitive adhesive composition.

In method A and method B, the coating of the pressure-sensitive adhesive composition can be carried out using a known coating device. Coating devices include, for example, blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, micro gravure coaters, rod blade coaters, lip coaters, die coaters and curtain coaters.

In method A and method B, the substrate used for coating the pressure-sensitive adhesive composition is not particularly limited. For example, the pressure-sensitive adhesive composition can be applied to various substrates such as resin substrates and glass substrates. When the substrate has a release sheet as described later, the adhesive composition can be applied onto the release sheet. Also, the pressure-sensitive adhesive composition can be directly applied onto the member to be adhered.

In Method A and Method B, the thickness of the pressure-sensitive adhesive composition after coating is not particularly limited, either, and can be appropriately set according to the desired thickness of the pressure-sensitive adhesive layer.

In Method A, the step of heat-treating the coating film can employ, for example, a step similar to a known method. By such heat treatment, curing of the pressure-sensitive adhesive composition progresses and volatile matter disappears to form a cured product. For example, when the pressure-sensitive adhesive composition contains the cross-linking agent, the reaction between the (meth)acrylic polymer having a functional group and the cross-linking agent proceeds to form a crosslinked body of the (meth)acrylic polymer. Thereby, the strength of the pressure-sensitive adhesive layer can be improved, and the adhesive force can also be improved. Therefore, when the pressure-sensitive adhesive composition contains a cross-linking agent, the method A is preferably used to form the pressure-sensitive adhesive layer.

In method A, in the step of heat-treating the coating film, the heating temperature can be, for example, 50° C. or higher and 150° C. or lower, and the heating time depends on the heating temperature and the target residual solvent concentration of the adhesive layer. The time can be set as appropriate, for example, 1 to 30 minutes. For the heat treatment, a known heating device such as a heating furnace or an infrared lamp can be used. After the heat treatment, if necessary, the cured product can be subjected to aging treatment under a predetermined environment.

In method B, the step of irradiating the coating film with an active energy ray can employ, for example, a step similar to a known method. Through such a process, for example, the photopolymerizable component in the pressure-sensitive adhesive composition is cured to form a cured product. For example, when the pressure-sensitive adhesive composition contains the polyfunctional monomer and the photopolymerization initiator, the polymerization reaction of the polyfunctional monomer proceeds. Thereby, the strength of the pressure-sensitive adhesive layer can be improved, and the adhesive force can also be improved. Therefore, when the pressure-sensitive adhesive composition contains a polyfunctional monomer in addition to the (meth)acrylic polymer having a functional group, it is preferable to form the pressure-sensitive adhesive layer by method B, and the pressure-sensitive adhesive composition has a functional group. It is particularly preferred to employ method B when the polyfunctional monomer, photoinitiator and polymerizable monomer M are included in addition to the (meth)acrylic polymer having

In method B, the active energy rays include ultraviolet rays, electron rays, visible rays, X-rays, ion rays, etc., and can be appropriately selected according to the photopolymerization initiator contained in the pressure-sensitive adhesive layer. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable. As the ultraviolet light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an extra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like can be used. The irradiation output of ultraviolet rays is preferably such that the integrated light amount is 100 to 10000 mJ/cm ² , more preferably 500 to 5000 mJ/cm ² .

The pressure-sensitive adhesive layer formed by methods such as Method A and Method B may be protected on one side or both sides thereof with a protective layer such as a protective sheet, if necessary.

The thickness of the pressure-sensitive adhesive layer can be appropriately set according to the application, and is not particularly limited. For example, the thickness of the adhesive layer is preferably 10-1000 μm, more preferably 20-500 μm, even more preferably 100-400 μm. In particular, since the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition of the present invention and has high transparency, high transparency can be maintained even if the pressure-sensitive adhesive layer is thickened. In addition, the thickness of an adhesive layer means the sum total of the thickness of each layer, when an adhesive layer has a multilayer laminated structure.

The gel fraction of the pressure-sensitive adhesive layer is not particularly limited. For example, it is preferably 30 to 99%, more preferably 50 to 95%, in terms of easily having excellent adhesive strength.

The gel fraction of the pressure-sensitive adhesive layer is a value measured by the following method. First, about 0.1 g of the adhesive sheet (adhesive layer) is collected in a sample bottle, 30 ml of ethyl acetate is added, and shaken for 24 hours. Thereafter, the contents of the sample bottle are filtered through a 200-mesh stainless wire mesh, and the residue on the wire mesh is dried at 120° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the following formula 1
Gel fraction (% by mass) = (dry mass/collected mass of pressure-sensitive adhesive layer) x 100 Equation 1
The gel fraction can be obtained by

The adhesive strength of the adhesive layer is, for example, 20 N/25 mm or more, preferably 30 N/25 mm or more, and more preferably 35 N/25 mm or more. Thereby, the adhesive sheet tends to have excellent adhesive strength.

The adhesive strength of the adhesive layer is a value measured by the following method. The pressure-sensitive adhesive layer is attached to a 75 μm-thick polyester film (A4300 manufactured by Toyobo Co., Ltd.) treated for easy adhesion, and cut so that the portion to be attached to the adherend has a width of 25 mm and a length of 80 mm to obtain a measurement sample. This sample is attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then press-bonded by reciprocating twice with a roller of 2 kg. After that, it is treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then left to stand for one day at an atmospheric pressure and a temperature of 23° C. and a humidity of 50%. Then, the adhesive strength of the sample including each adherend is measured under the same environment by Shimadzu AGX-500NX while the unbonded portion is gripped and pulled in the direction of 180° C. at a pulling speed of 300 mm/min. Let the value obtained by this measurement be the adhesive strength of an adhesive layer.

The high-temperature adhesive strength of the adhesive layer is, for example, 10 N/25 mm or more, preferably 15 N/25 mm or more. Thereby, the pressure-sensitive adhesive sheet tends to have excellent heat-resistant adhesive strength.

The high-temperature adhesive strength of the adhesive layer is a value measured by the following method. The pressure-sensitive adhesive layer is attached to a 75 μm-thick polyester film (A4300 manufactured by Toyobo Co., Ltd.) treated for easy adhesion, and cut so that the portion to be attached to the adherend has a width of 25 mm and a length of 80 mm to obtain a measurement sample. This sample is attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then press-bonded by reciprocating twice with a roller of 2 kg. After that, it is treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then left to stand for one day at atmospheric pressure and room temperature. Next, the sample containing each adherend was placed in RTC-1210A manufactured by Shimadzu Corporation, left to stand in a 95 ° C. heating environment for 30 minutes, and under the same environment, the unbonded part was grasped and pulled at a speed of 300 mm / The adhesive force is measured while pulling in the direction of 180° C. at min. Let the value obtained by this measurement be the high temperature adhesive strength of an adhesive layer.

The haze of the adhesive layer can be less than 1% at a thickness of 175 μm. Thereby, the pressure-sensitive adhesive sheet tends to have excellent transparency. In particular, since the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing zeolite particles of a specific size, it tends to have high transparency even if it is thicker than conventional ones. More preferably, the haze of the pressure-sensitive adhesive layer is 0.8% or less at a thickness of 175 μm.

The haze of the pressure-sensitive adhesive layer is a value measured by the following method. One side of the pressure-sensitive adhesive layer with a thickness of 175 μm is glass (Matsunami width 52 mm, length 76 mm, thickness 1 mm), and the other side is polycarbonate (Mitsubishi Corporation MR58 width 55 mm, length 80 mm, thickness 1 mm). to form a laminate. After that, the laminate is treated for 30 minutes in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa, and left to stand for one day at atmospheric pressure and room temperature. Next, the haze value of the laminate is measured with HM-150 of Murakami Color Research Laboratory.

(adhesive sheet)
The pressure-sensitive adhesive sheet of the present invention includes the pressure-sensitive adhesive layer. The structure of such a pressure-sensitive adhesive sheet is not particularly limited as long as it has the pressure-sensitive adhesive layer, and for example, it may have the same structure as a known pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet can be a single-layer pressure-sensitive adhesive sheet composed only of the pressure-sensitive adhesive layer. Alternatively, the adhesive sheet can be an adhesive sheet with a substrate on one side or both sides. The adhesive sheet may be either a single-sided adhesive sheet or a double-sided adhesive sheet.

When the pressure-sensitive adhesive sheet is provided with a substrate on one side or both sides, the substrate is not particularly limited. material can be mentioned. As the transparent substrate, general films used in the optical field such as polyethylene terephthalate film, acrylic film, polycarbonate film, triacetyl cellulose film, and cycloolefin polymer film can be used. Further, an easy-adhesion layer may be provided on the pressure-sensitive adhesive layer side of these transparent substrates. Furthermore, a functional layer such as a hard coat layer, an antireflection layer, an antifouling layer, or an ultraviolet absorption layer may be provided on the opposite side of the transparent substrate from the pressure-sensitive adhesive layer.

Specific examples of the adhesive sheet include a single-layer adhesive sheet consisting of an adhesive layer, a multilayer adhesive sheet having a plurality of laminated adhesive layers, and a multilayer adhesive sheet having another adhesive layer laminated between adhesive layers. multi-layer pressure-sensitive adhesive sheet in which a support is laminated between pressure-sensitive adhesive layers, and a multi-layer pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one side of a support and another pressure-sensitive adhesive layer is laminated on the other side An adhesive sheet is mentioned. When the pressure-sensitive adhesive sheet has a support, the support may be of the same type as the transparent substrate, for example.

Moreover, the pressure-sensitive adhesive sheet of the present invention can include a pressure-sensitive adhesive sheet with a release sheet provided with release sheets on both sides. The pressure-sensitive adhesive sheet with a release sheet can have a pair of release sheets with different release forces on both sides of the pressure-sensitive adhesive sheet.

As the release sheet, a release laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low-polarity base material. is mentioned.

Papers and polymer films are used as the base material for the release sheet in the release laminated sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition-type or condensation-type silicone-based release agent or a compound containing a long-chain alkyl group is used. In particular, an addition-type silicone-based release agent having high reactivity is preferably used. Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. be done. In addition, the silicone release agent may contain a silicone resin which is an organic silicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ ═CH(CH ₃ ) SiO _1/2 units. preferable. Specific examples of silicone resins include BY24-843, SD-7292, SHR-1404, etc. manufactured by Dow Corning Toray Silicone Co., Ltd., and KS-3800, X92-183, etc. manufactured by Shin-Etsu Chemical Co., Ltd.

A commercially available product may be used as the peelable laminate sheet. For example, a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Limited, a heavy separator film, and a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Limited, a light separator film can be used.

The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and for example, a wide variety of known pressure-sensitive adhesive sheet production methods can be employed.

The pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding optical members, for example. That is, the pressure-sensitive adhesive sheet of the present invention can be used as an optical pressure-sensitive adhesive sheet. Examples of optical members include constituent members in optical products such as touch panels and image display devices. Examples of constituent members of the touch panel include an ITO film in which an ITO film is provided on a transparent resin film, an ITO glass in which an ITO film is provided on the surface of a glass plate, a transparent conductive film in which a transparent resin film is coated with a conductive polymer, Examples include hard coat films and anti-fingerprint films. Examples of constituent members of the image display device include antireflection films, oriented films, polarizing films, retardation films, brightness enhancement films and the like used in liquid crystal display devices. Moreover, the pressure-sensitive adhesive sheet of the present invention may be used for bonding modules such as a liquid crystal module and a touch panel module. The optical member can be made of materials such as glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

(Production example 1)
350 g of n-butyl acrylate, 150 g of 2-hydroxyethyl acrylate and 750 g of ethyl acetate were charged into a 2 L flask equipped with a stirrer, nitrogen inlet tube, condenser and thermometer, and the mixture was replaced with nitrogen at a nitrogen flow rate of 300 ml/min for 60 minutes. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 70° C. in a water bath. Then, 0.15 g of AIBN (2,2-azobis(isobutyronitrile)) was added and reacted for 2 hours while controlling exotherm, after which 0.5 g of AIBN was added and reacted for 6 more hours. After cooling, a (meth)acrylic polymer solution was obtained as a (meth)acrylic polymer having a functional group. The resulting solution had a solid content concentration of 35% by mass, and the (meth)acrylic polymer had a mass average molecular weight of 600,000.

(Production example 2)
750 g of 2-ethylhexyl acrylate, 250 g of 4-hydroxybutyl acrylate and 0.4 g of n-dodecylmercaptan were charged into a 2 L flask equipped with a stirrer, a nitrogen inlet tube, a condenser tube and a thermometer. The atmosphere was replaced with nitrogen for 1 minute. After that, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath for heating. Next, 0.15 g of AIBN was added, and the mixture was reacted for 30 minutes while controlling heat generation, and then cooled to obtain a solution of (meth)acrylic polymer A as a (meth)acrylic polymer having a functional group. To this solution, the above-mentioned acrylic monomers, that is, 2-ethylhexyl acrylate and 4-hydroxybutyl acrylate were added in a flask at a mass ratio of 75:25. Acquired 10,000 acrylic syrup.

(Production example 3)
700 g of butyl acrylate, 290 g of 4-hydroxybutyl acrylate, 10 g of acrylic acid and 0.4 g of n-dodecyl mercaptan were charged into a 2 L flask equipped with a stirrer, nitrogen inlet tube, condenser and thermometer, and the nitrogen flow rate was 300 ml/min. After purging with nitrogen for 60 minutes, the nitrogen flow rate was lowered to 100 ml/min, and the temperature was raised to 60° C. in a water bath. Next, 0.15 g of AIBN was added, and the mixture was reacted for 30 minutes while controlling heat generation, and then cooled to obtain a solution of (meth)acrylic polymer A as a (meth)acrylic polymer having a functional group. To this solution, butyl acrylate, 4-hydroxybutyl acrylate, and acrylic acid were put into a flask at a mass ratio of 70:29:1, and acrylic syrup having a solid content concentration of 20% by mass and a weight average molecular weight of 400,000 was added. Obtained.

(Example 1)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, to 100 parts by mass (in terms of polymer component) of the (meth)acrylic polymer obtained in Production Example 1, 0.3 parts by mass of "Coronate L" (manufactured by Tosoh), which is an isocyanate cross-linking agent as a cross-linking agent, silane 1 part by mass of "X-41-1810" manufactured by Shin-Etsu Chemical Co., Ltd. as a coupling agent, and 0.5 parts by mass of "Zeoal 4A-50 D (n50)" manufactured by Nakamura Choukou Co., Ltd. having a primary average particle diameter of 50 nm as zeolite particles. was added, and the pressure-sensitive adhesive composition was obtained as a coating liquid by stirring and defoaming. This coating solution is coated on a 50 μm polyester film coated with a silicone release agent so that the thickness of the adhesive layer after drying is 58 μm, and dried at a dryer temperature of 80 ° C. for 2 minutes to remove the adhesive layer. Obtained. Three adhesive layers of 58 µm each were laminated, pressed with a roller, and allowed to stand at room temperature for 7 days to obtain a pressure-sensitive adhesive sheet with a thickness of 175 µm.

(Example 2)
A pressure-sensitive adhesive composition was prepared according to the blending amounts (parts by mass) shown in Table 1 below. Specifically, IGM RESUNS B.I. V. 0.4 parts by mass of "EsacureOne" manufactured by Shin-Nakamura Chemical Co., Ltd., 0.25 parts by mass of "A-200" (polyethylene glycol #200 diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, and "KBM" manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent -5103", and 1 part by mass of "Zeoal ZSM-5 D (n50)" manufactured by Nakamura Choukou Co., Ltd., which has a primary average particle size of 100 nm as zeolite particles, and are stirred and defoamed. to obtain a pressure-sensitive adhesive composition as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Example 3)
IGM RESUNS B.I. V. 0.4 parts by mass of "EsacureOne" manufactured by Co., Ltd., 0.3 parts by mass of "A-200" manufactured by Shin-Nakamura Chemical Co., Ltd. as a polyfunctional monomer, 1 part by mass of "KBM-402" manufactured by Shin-Etsu Chemical as a silane coupling agent, As zeolite particles, 0.5 parts by mass of "Zeoal 4A-50 D (n50))" manufactured by Nakamura Choukou Co., Ltd. was added, and defoamed with stirring to obtain a pressure-sensitive adhesive composition as a coating liquid. This coating solution was applied onto a 50 μm polyester film coated with a silicone release agent so that the adhesive layer had a thickness of 175 μm, and a 50 μm polyester film coated with a silicone release agent was further coated thereon. piled up. Then, after irradiation with a chemical lamp at a light intensity of 7 mW/cm ² for 2 minutes, irradiation was performed with a high-pressure mercury lamp so that the integrated light amount was 1500 mJ/cm ² to obtain a pressure-sensitive adhesive sheet with a thickness of 175 μm.

(Example 4)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that no silane coupling agent was used.

(Comparative example 1)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 2, except that no zeolite particles were added.

(Comparative example 2)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that the zeolite particles were changed to "HSZ-800 822HOA" manufactured by Tosoh having an average primary particle size of 5 μm.

(Comparative Example 3)
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the amount of zeolite particles 4A-50 used was 10 parts by mass.

(Evaluation method)
[Gel fraction]
About 0.1 g of the adhesive sheet thus obtained was collected in a sample bottle, added with 30 ml of ethyl acetate, and shaken for 24 hours. Thereafter, the contents of the sample bottle were filtered through a 200-mesh stainless wire mesh, and the residue on the wire mesh was dried at 120° C. for 1 hour to measure the dry mass (g). The gel fraction was obtained from the obtained dry mass according to the formula 1 above.

[Adhesive force]
The adhesive layer (adhesive sheet) is attached to a 75 μm thick polyester film (Toyobo A4300) that has been treated for easy adhesion, and is cut so that the part to be attached to the adherend has a width of 25 mm and a length of 80 mm. Got a sample. This sample was attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then crimped by reciprocating twice with a roller of 2 kg. After that, it was treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then allowed to stand at atmospheric pressure and a temperature of 23° C. and a humidity of 50% for one day. Next, the adhesive strength of the sample containing each adherend was measured under the same environment by Shimadzu AGX-500NX while the unbonded portion was grasped and pulled in the direction of 180° C. at a pulling speed of 300 mm/min. The value obtained by this measurement was defined as the adhesive strength of the adhesive layer, and was evaluated according to the following criteria.
A: The adhesive strength was 35 N/25 mm or more.
B: The adhesive strength was 20 N/25 mm or more and less than 35 N/25 mm.
C: The adhesive strength was less than 20 N/25 mm.

[High temperature adhesive strength]
The adhesive layer (adhesive sheet) is attached to a 75 μm thick polyester film (Toyobo A4300) that has been treated for easy adhesion, and is cut so that the part to be attached to the adherend has a width of 25 mm and a length of 80 mm. Got a sample. This sample was attached to a float glass having a thickness of 1 mm, a width of 115 mm, and a length of 75 mm in a width of 25 mm and a length of 50 mm, and then crimped by reciprocating twice with a roller of 2 kg. After that, it was treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then allowed to stand under atmospheric pressure and room temperature for one day. Next, the sample containing each adherend was placed in RTC-1210A manufactured by Shimadzu Corporation, left to stand in a 95 ° C. heating environment for 30 minutes, and under the same environment, the unbonded part was grasped and pulled at a speed of 300 mm / The adhesive force was measured while pulling in the direction of 180° C. at min. The value obtained by this measurement was defined as the high-temperature adhesive strength of the adhesive layer, and was evaluated according to the following criteria.
A: The adhesive strength was 15 N/25 mm or more.
B: The adhesive strength was 10 N/25 mm or more and less than 15 N/25 mm.
C: The adhesive strength was less than 10 N/25 mm.

[Haze (transparency evaluation)]
One side of the pressure-sensitive adhesive layer with a thickness of 175 μm is glass (Matsunami width 52 mm, length 76 mm, thickness 1 mm), and the other side is polycarbonate (Mitsubishi Corporation MR58 width 55 mm, length 80 mm, thickness 1 mm). to obtain a laminate. After that, the laminate was treated in an autoclave at a temperature of 30° C. and a pressure of 0.5 MPa for 30 minutes, and then allowed to stand under atmospheric pressure and room temperature for one day. Next, the haze value of the laminate was measured with HM-150 of Murakami Color Research Laboratory and evaluated according to the following criteria.
A: The haze value was less than 1.
C: The haze value was 1 or more.

Table 1 shows the results of each evaluation in addition to the production conditions for the pressure-sensitive adhesive sheets of the above Examples and Comparative Examples. From Table 1, it was found that the pressure-sensitive adhesive sheets obtained in Examples have excellent adhesive strength while maintaining high transparency, and are also excellent in heat-resistant adhesive strength. On the other hand, the pressure-sensitive adhesive sheet of Comparative Example 1 does not contain zeolite particles having a predetermined size, and is particularly inferior in heat-resistant adhesive strength. , adhesive strength, heat-resistant adhesive strength and transparency were all inferior. The pressure-sensitive adhesive sheet of Comparative Example 3 contained too much zeolite particles, and was inferior in all of the adhesive strength, heat-resistant adhesive strength, and transparency.

Claims (4)

containing at least a (meth)acrylic polymer having a functional group and zeolite particles,
The zeolite particles have an average primary particle size of 20 to 150 nm,
The pressure-sensitive adhesive composition, wherein the content of the zeolite particles is 0.01 to 5 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer. The adhesive composition according to claim 1, further comprising a silane coupling agent. 3. The pressure-sensitive adhesive composition according to claim 1, further comprising at least one of a cross-linking agent and a polyfunctional monomer. A pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 3,
A pressure-sensitive adhesive sheet having a haze of less than 1% when the pressure-sensitive adhesive has a thickness of 175 μm.