WO2020162518A1

WO2020162518A1 - Adhesive sheet and layered product

Info

Publication number: WO2020162518A1
Application number: PCT/JP2020/004466
Authority: WO
Inventors: 山本　真之; 貴迪山口
Original assignee: 王子ホールディングス株式会社
Priority date: 2019-02-08
Filing date: 2020-02-06
Publication date: 2020-08-13
Also published as: TW202039743A

Abstract

Provided are: an adhesive sheet having excellent outgas resistance; and a layered product comprising the adhesive sheet. This adhesive sheet comprises an adhesive agent layer. The adhesive agent layer contains a crosslinked (meth)acrylic copolymer, a polymerizable monomer having a polymerizable double bond in the molecule, and a photopolymerization initiator. The crosslinked (meth)acrylic copolymer has a structure in which a crosslinkable (meth)acrylic copolymer is crosslinked by a crosslinking agent. The polymerizable monomer includes a monofunctional monomer having a cyclic ether structure and/or a monofunctional monomer having a chain ether structure.

Description

Adhesive sheet and laminate

The present invention relates to an adhesive sheet and a laminate including the adhesive sheet.

Adhesive sheets are used, for example, for bonding members together, and are widely used in various fields. In recent years, such an adhesive sheet has also been used for a display device such as a liquid crystal display (LCD) or an input device such as a touch panel. By using the pressure-sensitive adhesive sheet for bonding the members such as the optical display constituting the display device or the input device, various devices can be manufactured with high accuracy and easily.

In a display device or an input device, for example, a resin cover panel and a layer composed of a touch panel sensor or the like are pasted together with an adhesive sheet, and an adhesive sheet suitable for such an application. Have been proposed. For example, Patent Document 1 discloses a (meth)acrylic acid alkyl ester, a (meth)acrylic acid ester polymer containing a reactive functional group-containing monomer having a reactive functional group in the molecule, and N-vinylcarboxylic acid amide, A pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a crosslinking agent (B) has been proposed. It is said that the blister resistance and the moisture and heat whitening resistance can be improved by using an adhesive sheet based on an acrylic polymer having such a specific structure in an input device such as a touch panel. Further, Patent Document 2 discloses an optical pressure-sensitive adhesive sheet including a pressure-sensitive adhesive layer having a predetermined shear storage elastic modulus, which is formed from a pressure-sensitive adhesive composition containing an acrylic polymer having a specific structure.

Japanese Patent Laid-Open No. 2018-172537 Japanese Patent Laid-Open No. 2012-87240

However, when a member such as a resin cover panel is pasted with an adhesive sheet, there is a problem that gas (so-called outgas) generated from the member such as the cover panel may cause bubbles, floating, and peeling at the bonding interface. .. For example, outgassing can be suppressed by protecting the cover panel or the like to be bonded with a hard coat layer or the like. However, in this case, there is a problem that the types of members to be bonded are restricted. In other words, a member that is likely to generate outgas and has a problem that it is difficult to use a conventional pressure-sensitive adhesive sheet for a member that is not protected by a hard coat layer or the like in that the outgas resistance is poor. It was In the technique disclosed in Patent Document 1 or the like, although a certain improvement in blister resistance (outgas resistance) can be expected, for example, when a polycarbonate having no hard coat layer is used, the blister resistance is insufficient. No, there was room for further improvement.

The present invention has been made in view of the above, and it is an object of the present invention to provide a pressure-sensitive adhesive sheet having excellent outgas resistance and a laminate including the pressure-sensitive adhesive sheet.

As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using a monofunctional monomer having a specific ether structure, and have completed the present invention. It was

That is, the present invention includes the subject matter described in the following sections, for example.
Item 1
An adhesive sheet comprising an adhesive layer,
The pressure-sensitive adhesive layer contains a crosslinked (meth)acrylic copolymer, a polymerizable monomer having a polymerizable double bond in the molecule, and a photopolymerization initiator,
The crosslinked (meth)acrylic copolymer has a structure in which the crosslinkable (meth)acrylic copolymer is crosslinked with a crosslinking agent,
The pressure-sensitive adhesive sheet, wherein the polymerizable monomer contains at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure.
Item 2
Item 5. The pressure-sensitive adhesive sheet according to item 1, wherein the monofunctional monomer having a cyclic ether structure is contained in an amount of 5 to 30 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
Item 3
Item 3. The pressure-sensitive adhesive sheet according to Item 1 or 2, wherein the cyclic ether structure is a 4- to 6-membered ring.
Item 4
Item 5. The pressure-sensitive adhesive sheet according to Item 1, wherein the monofunctional monomer having a chain ether structure is contained in an amount of 5 to 50 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
Item 5
Item 5. The pressure-sensitive adhesive sheet according to any one of Items 1 to 4, wherein the polymerizable monomer contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule.
Item 6
Item 6. The pressure-sensitive adhesive sheet according to Item 5, wherein the polyfunctional monomer has a bisphenol skeleton in its molecule.
Item 7
Item 7. The pressure-sensitive adhesive sheet according to item 5 or 6, wherein the polyfunctional monomer is contained in an amount of 1 to 15 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
Item 8
Item 8. The pressure-sensitive adhesive sheet according to any one of Items 1 to 7, which is used for bonding with one kind of first member selected from the group consisting of a resin plate, a resin sheet and a resin film.
Item 9
Item 9. The pressure-sensitive adhesive sheet according to Item 8, which is used for laminating the first member and one kind of second member selected from the group consisting of a glass plate, a resin film and a resin plate.
Item 10
Item 10. A laminate comprising the pressure-sensitive adhesive sheet according to any one of Items 1 to 9 or a cured product thereof.
Item 11
Item 11. The laminate according to Item 10, further including the first member, and having a structure in which the first member and the layer of the pressure-sensitive adhesive sheet or a cured product thereof are laminated.

The pressure-sensitive adhesive sheet according to the present invention has excellent outgas resistance, and bubbles, floating, and peeling hardly occur after bonding.

Hereinafter, embodiments of the present invention will be described in detail. In the present specification, the expressions "containing" and "including" include the concepts of "containing", "including", "consisting essentially of" and "consisting solely of".

1. Adhesive sheet The adhesive sheet of the present invention comprises an adhesive layer. The pressure-sensitive adhesive layer contains a crosslinked (meth)acrylic copolymer, a polymerizable monomer having a polymerizable double bond in the molecule, and a photopolymerization initiator, and the crosslinked (meth)acrylic copolymer The coalesced has a structure in which a crosslinkable (meth)acrylic copolymer is crosslinked with a crosslinking agent, and the polymerizable monomer is a monofunctional monomer having a cyclic ether structure or a monofunctional monomer having a chain ether structure. At least one of the functional monomers is included.

In this specification, “(meth)acrylic” means “acrylic” or “methacrylic”, and “(meth)acrylate” means “acrylate” or “methacrylate”.

<Crosslinked (meth)acrylic copolymer>
The crosslinked (meth)acrylic copolymer is a polymer having a crosslinked structure formed by reacting a crosslinkable (meth)acrylic copolymer with a crosslinking agent. As such a crosslinked (meth)acrylic copolymer, for example, known crosslinked (meth)acrylic copolymers used in pressure-sensitive adhesive sheets can be widely applied.

(Crosslinkable (meth)acrylic copolymer)
The crosslinkable (meth)acrylic copolymer can have a structure in which a functional group exhibiting crosslinking reactivity is bonded to the (meth)acrylic copolymer skeleton. The functional group exhibiting crosslinking reactivity is not particularly limited, and examples thereof include a hydroxyl group, a carboxy group, an amino group, an amide group, an epoxy group, a thiol group and an isocyanate group. Since it is preferable that the pressure-sensitive adhesive layer is acid-free in that yellowing and corrosion are less likely to occur, the crosslinkable (meth)acrylic copolymer is also preferably acid-free. Therefore, it is more preferable that the functional group exhibiting crosslinking reactivity does not contain a carboxy group. The functional group exhibiting particularly preferable crosslinking reactivity is a hydroxyl group, and in this case, a crosslinked (meth)acrylic copolymer is also easily formed.

The crosslinkable (meth)acrylic copolymer can have, for example, a monomer unit having a functional group exhibiting crosslinking reactivity and a monomer unit having no functional group exhibiting crosslinking reactivity. .. In this case, the crosslinkable (meth)acrylic copolymer can be obtained, for example, by copolymerizing a monomer having a functional group exhibiting crosslinking reactivity and a monomer having no functional group exhibiting crosslinking reactivity. it can. Hereinafter, a monomer having a functional group exhibiting crosslinking reactivity will be referred to as “monomer A”, and a monomer having no functional group exhibiting crosslinking reactivity will be referred to as “monomer B”.

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

The type of the hydroxyl group-containing (meth)acrylic monomer is not particularly limited as long as it has one or more hydroxyl groups in the molecule. For example, as the hydroxyl group-containing (meth)acrylic monomer, 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- Examples thereof include 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 at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and 6-hydroxyhexyl (meth)acrylate. Is preferred. In this case, a pressure-sensitive adhesive sheet having excellent outgas resistance is easily obtained. The hydroxyl group-containing (meth)acrylic monomer may be used alone or in combination of two or more different types.

The type of the 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, as the carboxy group-containing (meth)acrylic monomer, (meth)acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, citraconic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-( Examples thereof include (meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxyethyl (meth)acrylate, and carboxypolycaprolactone mono(meth)acrylate.

As described above, the monomer A is preferably a hydroxyl group-containing (meth)acrylic monomer in that the pressure-sensitive adhesive sheet is preferably acid-free. The monomer A may 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. If the pressure-sensitive adhesive sheet contains an acid, for example, the content of the monomer having an acid group can be 5% by mass or less based on the total mass of the monomer for forming the crosslinkable (meth)acrylic copolymer, It is preferably 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less.

Examples of the monomer B include (meth)acrylates having a linear, branched, or cyclic alkyl group, or (meth)acrylates having an aromatic ring. Specific examples of the monomer B include methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, isopropyl(meth)acrylate, isooctyl(meth)acrylate, 2- Examples thereof include ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl, and (meth)acrylate. 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 (meth). It is preferably an alkyl (meth)acrylate such as an acrylate. In this case, a pressure-sensitive adhesive sheet having excellent outgas resistance is easily obtained. The monomer B can be used alone or in combination of two or more different kinds.

The crosslinkable (meth)acrylic copolymer can be produced, for example, by polymerizing the monomer A and the monomer B by a known polymerization method. As the polymerization method, for example, solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like can be adopted.

In the polymerization for obtaining the crosslinkable (meth)acrylic copolymer, the use ratio of the monomer A and the monomer B is not particularly limited and may be appropriately set depending on the target crosslinkable (meth)acrylic copolymer. it can. For example, 0.5 to 60 parts by mass of the monomer A (monomer having a crosslinkable functional group) can be contained per 100 parts by mass of the total amount of the monomers A and B. In this case, the pressure-sensitive adhesive sheet can have a desired pressure-sensitive adhesive strength, and deterioration of outgas resistance is unlikely to occur. It is preferable that 1 to 55 parts by mass of the monomer A is contained per 100 parts by mass of the total amount of the monomers A and B.

In the polymerization for obtaining the crosslinkable (meth)acrylic copolymer, a polymerizable monomer other than the monomer A and the monomer B can be used in combination, if necessary. As such a polymerizable monomer, for example, a radically polymerizable monomer copolymerizable with the monomer A and the monomer B other than the (meth)acrylate compound can be mentioned. Specific examples thereof include vinyl acetate and styrene. The amount of the radically polymerizable monomer copolymerizable with the monomer A and the monomer B is preferably 20 parts by mass or less based on 100 parts by mass of the total amount of the monomers A and B, for example.

In the production of the crosslinkable (meth)acrylic copolymer, the use ratio (mass ratio) of the monomer A and the monomer B is included in the crosslinkable (meth)acrylic copolymer obtained by the polymerization of the monomers A and B. Corresponds to the mass ratio of the monomer unit having a functional group exhibiting crosslinking reactivity and the monomer unit having no functional group exhibiting crosslinking reactivity.

In the polymerization method for obtaining the crosslinkable (meth)acrylic copolymer, a solvent can be used if necessary. The type of solvent is not particularly limited, and, for example, well-known organic solvents used in polymerization can be widely 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; aromatic compounds such as toluene, xylene and benzene. The amount of the solvent used in the polymerization reaction is not particularly limited.

In the polymerization method for obtaining the crosslinkable (meth)acrylic copolymer, a polymerization initiator can be used if necessary. For example, a well-known polymerization initiator used in general polymerization is widely used. can do. Examples of the polymerization initiator include azobisisobutyronitrile, 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, 1,1′-azobis(cyclohexanecarbonitrile), Examples thereof include di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, and photopolymerization initiators (Irgacure or Omnirad (registered trademark) series).

The concentration of the polymerization initiator is not particularly limited, and can be appropriately adjusted, for example, within a range in which the obtained polymer of the crosslinkable (meth)acrylic copolymer has a desired molecular weight. For example, the polymerization initiator may be used in an amount of 0.01 to 5 parts by mass based on 100 parts by mass of the total amount of the monomer A and the monomer B.

The polymerization for obtaining the crosslinkable (meth)acrylic copolymer can be performed, for example, in an atmosphere of an inert gas such as nitrogen.

The polymerization time and the polymerization temperature for obtaining the crosslinkable (meth)acrylic copolymer are not limited, and may be appropriately set depending on the types of monomers A and B to be used, the amounts used, the polymerization reactivity, and the like. it can. For example, the polymerization reaction can be carried out under the conditions of 20 to 100° C. and 1 to 24 hours.

The weight average molecular weight of the crosslinkable (meth)acrylic copolymer is not particularly limited, and can be 100,000 to 2,000,000, and 400,000 to 100,000, for example, from the viewpoint that the pressure-sensitive adhesive sheet is unlikely to lose its adhesive strength. It is more preferable to set it to 10,000.

The weight average molecular weight in the present invention is a polystyrene equivalent weight average molecular weight measured by a gel permeation chromatography (GPC) method. The GPC device used in the GPC method is not particularly limited, and a commercially available GPC measuring instrument such as LC-2000Plus series manufactured by JASCO Corporation, RI-2031Plus, UV-2075Plus as a detector can be used. In this case, for example, a GPC column configured by connecting four Shodo 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 an eluent, and the measurement is performed at a flow rate of 1.0 ml/min. Usually, a calibration curve is prepared using standard polystyrene, and the weight average molecular weight (Mw) can be obtained by polystyrene conversion.

The crosslinkable (meth)acrylic copolymer is a so-called random copolymer in which a monomer unit having a functional group exhibiting crosslinking reactivity and a monomer unit having no functional group exhibiting crosslinking reactivity are randomly arranged. It can be a polymer. Alternatively, the crosslinkable (meth)acrylic copolymer may have other structures such as block polymers.

(Crosslinking agent)
The crosslinking agent is a component for promoting the crosslinking of the crosslinkable (meth)acrylic copolymer. In particular, the cross-linking agent can react with the functional group exhibiting cross-linking reactivity in the cross-linkable (meth)acrylic copolymer.

The type of cross-linking agent is not particularly limited, and known cross-linking agents can be widely used. For example, the crosslinking agent may include an isocyanate crosslinking agent and an epoxy crosslinking agent.

The type of isocyanate crosslinking agent is not particularly limited, and known compounds can be widely used. As the isocyanate crosslinking agent, tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate and other polyisocyanates; cyclopentylene diisocyanate, cyclohexylene diisocyanate And alicyclic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and aromatic isocyanate such as 4,4′-diphenylmethane diisocyanate. The isocyanate crosslinking agent may be used alone or in combination of two or more different types. Further, it is more preferable to use a trifunctional derivative such as an adduct body, a nurate body, or a burette body obtained from the above-mentioned diisocyanate as an isocyanate crosslinking agent.

Examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol. Diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexanone, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl Examples thereof include ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like.

When the crosslinkable (meth)acrylic copolymer is crosslinked with a crosslinking agent to obtain a crosslinked (meth)acrylic copolymer, the use ratio of the crosslinkable (meth)acrylic copolymer and the crosslinking agent is not particularly limited. For example, 0.01 to 5 parts by mass of the crosslinking agent can be used per 100 parts by mass of the crosslinkable (meth)acrylic copolymer. In this case, the pressure-sensitive adhesive sheet can have a desired adhesive force. It is preferable to use 0.05 to 1 part by mass of the crosslinking agent per 100 parts by mass of the crosslinkable (meth)acrylic copolymer.

When cross-linking the cross-linkable (meth)acrylic copolymer with a cross-linking agent, other components can be used in combination, if necessary. Examples of the other component include a silane coupling agent. When a silane coupling agent is also used, the adhesive strength of the adhesive sheet is likely to be improved.

The type of silane coupling agent is not particularly limited, and, for example, known compounds can be widely used. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldialkoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-glycidoxy. Examples include propyltriacoxysilane γ-methacryloxypropyltrialkoxysilane, γ-chloropropyltrialkoxysilane, γ-methacryloxypropyldialkoxysilane, γ-mercaptopropyltrialkoxysilane, and vinyltrialkoxysilane.

When a silane coupling agent is used in combination for crosslinking the crosslinkable (meth)acrylic copolymer with a crosslinking agent, the amount of the silane coupling agent used is 0.1 to 100 parts by weight per 100 parts by weight of the crosslinkable (meth)acrylic copolymer. 5 parts by mass can be contained.

<Polymerizable monomer having a polymerizable double bond in the molecule>
In the pressure-sensitive adhesive sheet, the polymerizable monomer having a polymerizable double bond in the molecule includes at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure. That is, the polymerizable monomer having a polymerizable double bond in the molecule, when containing either one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure, It may include both.

(Cyclic ether-containing monomer)
The monofunctional monomer having a cyclic ether structure is a monomer having both a polymerizable double bond and a cyclic ether structure in the molecule. Hereinafter, the polymerizable monomer having a polymerizable double bond in the molecule will be referred to as “polymerizable monomer M”. In addition, a monomer having both a polymerizable double bond and a cyclic ether structure in the molecule is referred to as “cyclic ether-containing monomer”.

The type of the cyclic ether-containing monomer contained in the polymerizable monomer M is not particularly limited as long as it is a radically polymerizable monomer having a cyclic ether structure in the molecule, and known cyclic ether-containing monomers are widely used. be able to. For example, the cyclic ether-containing monomer can have a group containing a cyclic ether structure in the side chain.

The cyclic ether structure is not particularly limited as long as it has a 3-membered ring or more, but the cyclic ether structure is more preferably a 4-membered ring or more from the viewpoint of easily improving the outgas resistance. That is, the cyclic ether structure is preferably other than a three-membered ring. Above all, it is preferable that the cyclic ether structure is a 4- to 6-membered ring, that is, one or more kinds of 4-membered ring, 5-membered ring and 6-membered ring.

The number of oxygen atoms among the atoms constituting the ring of the cyclic ether structure is not particularly limited as long as it is 1 or more. For example, the number of oxygen atoms can be 1 or 2. Of the atoms constituting the ring of the cyclic ether structure, the atoms other than oxygen atom are usually carbon atoms.

The cyclic ether structure is preferably a tetrahydrofuran structure. In this case, the pressure-sensitive adhesive sheet has particularly improved resistance to outgassing.

In the cyclic ether structure, atoms other than oxygen atoms (for example, carbon atoms) constituting the ring may have one or more substituents. The type of the substituent is not particularly limited, and examples thereof include an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, and more specifically. Examples thereof include a methyl group, an ethyl group, an n-propyl group and an i-propyl group.

When the cyclic ether structure has the above-mentioned substituents, the number of substituents and the bonding position are not particularly limited, and the effects of the present invention are not impaired in any case. Usually, the cyclic ether structure has one or two substituents.

Examples of the cyclic ether-containing monomer include (meth)acrylic ester having a cyclic ether structure. In this case, for example, the cyclic ether structure has a structure in which the cyclic ether structure is directly or indirectly bonded to the oxygen atom of the ester of the (meth)acrylic ester. When the cyclic ether structure has a structure indirectly bonded to the oxygen atom of the (meth)acrylic ester, for example, the group represented by the following general formula (1) or general formula (2) is cyclic with the oxygen atom of the ester and the cyclic group. It intervenes with the ether structure.
-(CH ₂ ) _m- (1)
(In the formula (1), m represents an integer of 1 to 5)

In the formula (1), m is preferably 1 to 2. In the formula (2), n is preferably 0-4.

Further specific examples of the cyclic ether-containing monomer include the compounds shown in the following (3-1) to (3-6).

The cyclic ether-containing monomer contained in the polymerizable monomer M may be one kind alone, or two or more different cyclic ether-containing monomers may be included.

In the adhesive sheet, the content of the cyclic ether-containing monomer is not particularly limited. From the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is more excellent, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer (monofunctional monomer having a cyclic ether structure) is added to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. 5 to 50 parts by mass is preferable.

More specifically, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer is preferably contained in an amount of 7 parts by mass or more, and more preferably 10 parts by mass or more, based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer. Particularly preferred. Further, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer is more preferably contained in an amount of 40 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. It is particularly preferable that the content is 25 parts by mass or less.

The polymerizable monomer M may also contain a monofunctional polymerizable monomer other than the cyclic ether-containing monomer as long as the effect of the present invention is not impaired. As such a monofunctional polymerizable monomer, for example, known monofunctional polymerizable monomers can be widely applied. The monofunctional polymerizable monomer other than the cyclic ether-containing monomer may be a chain ether-containing monomer described later. When the polymerizable monomer M contains a monofunctional polymerizable monomer other than the cyclic ether-containing monomer, its content is, for example, 10% by mass or less, preferably 10% by mass or less based on the total mass of the polymerizable monomer M. It can be 5 mass% or less, more preferably 1 mass% or less, and particularly preferably 0.1 mass% or less.

(Chain ether-containing monomer)
The monofunctional monomer having a chain ether structure is a monomer having both a polymerizable double bond and a chain ether structure in the molecule. Hereinafter, a monomer having both a polymerizable double bond and a chain ether structure in the molecule will be referred to as a “chain ether-containing monomer”.

The chain ether-containing monomer contained in the polymerizable monomer M is not particularly limited as long as it is a radical polymerizable monomer having a chain ether structure in the molecule, and a known chain ether-containing monomer may be used. Can be widely used. For example, the chain ether-containing monomer can have a group containing a chain ether structure in the side chain.

In the chain ether-containing monomer, the chain ether structure is not particularly limited. Examples of the chain ether structure include a structure having a structural unit represented by the following general formula (5).

In the formula (5), m is an integer of 1 to 4, k is an integer of 1 to 15, and R ¹ is an alkyl group or a group having an aromatic hydrocarbon.

In the formula (5), m is particularly preferably 1 or 2 from the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is particularly likely to be improved.

In the formula (5), k is particularly preferably 1 to 5 from the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is particularly likely to be improved.

In the above formula (5), when R ¹ is an alkyl group, its type is not particularly limited. The alkyl group may have any of a linear structure, a branched structure and a cyclic structure. For example, when the alkyl group is linear or branched, examples of such an alkyl group include an alkyl group having 1 to 10 carbon atoms, and an alkyl group having 1 to 5 carbon atoms is preferable. More preferably, it is an alkyl group having 1 to 4 carbon atoms. From the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is particularly likely to be improved, when R ¹ is an alkyl group, a particularly preferable alkyl group is a methyl group or an ethyl group.

When the alkyl group is cyclic, the alkyl group can have 3 or more carbon atoms, more preferably 4 or more carbon atoms, and particularly preferably 5 or more carbon atoms. When the alkyl group is cyclic, the alkyl group can have 20 or less carbon atoms, more preferably 15 or less, and particularly preferably 10 or less.

In the above formula (5), when R ¹ is a group having an aromatic hydrocarbon, the type thereof is not particularly limited, and examples thereof include a phenyl group and a benzyl group. The group having an aromatic hydrocarbon may further have a substituent on its aromatic ring. In this case, examples of the substituent include an alkyl group having 1 to 5 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, an amino group and the like. The number of substituents and the bonding position are not particularly limited. From the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is particularly likely to be improved, when R ¹ is a group having an aromatic hydrocarbon, a phenyl group is particularly preferable.

Examples of the chain ether-containing monomer include (meth)acrylic ester having a chain ether structure. In this case, for example, a chain ether structure has a structure in which a chain ether structure is directly or indirectly bonded to the oxygen atom of the ester of (meth)acrylic ester. When the chain ether structure has a structure indirectly bonded to the oxygen atom of the (meth)acrylic ester, for example, the group represented by the general formula (1) or the general formula (2) is the oxygen atom of the ester. Intervenes between the chain ether structure.

In the chain ether-containing monomer, a in the formula (1) is preferably 1-2. In the chain ether-containing monomer, n in the formula (2) is preferably 0-4.

Further specific examples of the chain ether-containing monomer include the compounds shown in (4-1) to (4-6) below.

The chain ether-containing monomer contained in the polymerizable monomer M may be one kind alone, or two or more different chain ether-containing monomers may be contained.

The content of the chain ether-containing monomer in the adhesive sheet is not particularly limited. From the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is more excellent, in the pressure-sensitive adhesive sheet, the chain ether-containing monomer (monofunctional monomer having a chain ether structure) is 100 parts by mass of the crosslinkable (meth)acrylic copolymer. 5 to 50 parts by mass is preferable.

More specifically, in the pressure-sensitive adhesive sheet, the chain ether-containing monomer is contained in an amount of preferably 7 parts by mass or more, and more preferably 10 parts by mass or more, based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer. Is particularly preferable. Further, in the pressure-sensitive adhesive sheet, the chain ether-containing monomer is more preferably contained in an amount of 40 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. , 25 parts by mass or less is particularly preferable.

The polymerizable monomer M may contain a monofunctional polymerizable monomer other than the chain ether-containing monomer as long as the effect of the present invention is not impaired. As such a monofunctional polymerizable monomer, for example, known monofunctional polymerizable monomers can be widely applied. The monofunctional polymerizable monomer other than the chain ether-containing monomer may be the cyclic ether-containing monomer. When the polymerizable monomer M contains a monofunctional polymerizable monomer other than the chain ether-containing monomer, the content thereof is, for example, 10% by mass or less based on the total mass of the polymerizable monomer M, preferably Can be 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less.

(Polyfunctional monomer)
The polymerizable monomer M also preferably contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule. In this case, in addition to the outgas resistance of the pressure-sensitive adhesive sheet being easily improved, shrinkage when the pressure-sensitive adhesive sheet is cured can be suppressed. Hereinafter, the polyfunctional monomer having two or more polymerizable double bonds in the molecule will be simply referred to as “polyfunctional monomer”.

The type of polyfunctional monomer is not particularly limited, and for example, known polyfunctional monomers used in pressure-sensitive adhesive sheets can be widely used. Among them, the polyfunctional monomer preferably has a bisphenol skeleton in its molecule, from the viewpoint that it is easier to suppress the shrinkage when the pressure-sensitive adhesive sheet is cured. More specifically, an alkylene oxide-modified (meth)acrylic ester having a bisphenol skeleton can be used as a polyfunctional monomer. In this case, the alkylene oxide is, for example, ethylene oxide, propylene oxide or the like. The number of alkylene oxide units can be, for example, 1 to 5.

Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, di(meth)acrylic acid 1, 4-butylene glycol, 1,9-nonanediol di(meth)acrylic acid, 1,6-hexanediol diacrylic acid, polybutylene glycol di(meth)acrylic acid, neopentyl glycol di(meth)acrylic acid, di(meth)acrylic acid ) Tetraethylene glycol acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, diacrylate of bisphenol A diglycidyl ether, trimethylolpropane tri(meth)acrylate, tri(meth)acrylic Examples thereof include (meth)acrylic acid esters of polyhydric alcohols such as acid pentaerythritol and pentaerythritol tetra(meth)acrylate, vinyl methacrylate and the like.

Examples of the polyfunctional monomer having a bisphenol skeleton in the molecule include diacrylate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, and diacrylate of bisphenol F diglycidyl ether.

As the polyfunctional monomer, a commercially available product may be used. For example, a trifunctional monomer M310 (trimethylolpropane PO modified triacrylate) or a trifunctional monomer M321 (trimethylolpropane propylene oxide modified triacrylate) manufactured by Toagosei Co., Ltd., Toagosei Co., Ltd. bifunctional monomer M211B (bisphenol A EO modified diacrylate), Toagosei Co., Ltd. bifunctional monomer "Aronix M208" (bisphenol F EO modified diacrylate), Osaka Organic Chemical Industry's bifunctional monomer " VISCOAT #700HV” (bisphenol A EO (3.8) adduct diacrylate) and the like.

In the polyfunctional monomer, the number of polymerizable double bonds in one molecule is not particularly limited as long as it is 2 or more. For example, in the polyfunctional monomer, the number of polymerizable double bonds in one molecule can be two.

The content of the polyfunctional monomer in the adhesive sheet is not particularly limited. From the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet and the shrinkage after curing are further suppressed, in the pressure-sensitive adhesive sheet, the polyfunctional monomer is 1 to 15 with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. It is preferably contained in an amount by mass.

In the pressure-sensitive adhesive sheet, the polyfunctional monomer is more preferably contained in an amount of 3 parts by mass or more, and particularly preferably 5 parts by mass or more, relative to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. In the pressure-sensitive adhesive sheet, the polyfunctional monomer is preferably contained in an amount of 12 parts by mass or less based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.

The polymerizable monomer M can be composed of only a monofunctional monomer and a polyfunctional monomer. Further, the polymerizable monomer M may be composed of only a cyclic ether-containing monomer and a polyfunctional monomer, or the polymerizable monomer M may be a chain ether-containing monomer and a polyfunctional monomer. It can also be configured with only.

<Photopolymerization initiator>
The photopolymerization initiator is a component that irradiates the polymerizable monomer M with light to cause a polymerization reaction (photopolymerization) to proceed. The type of the photopolymerization initiator is not particularly limited as long as it can photopolymerize the polymerizable monomer M, and for example, known photopolymerization initiators can be widely used.

The photopolymerization initiator is not particularly limited, but examples thereof include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-henylpropanone, 1-[4-( 2-Hydroxyethoxyl)-phenyl]-2-hydroxy-methylpropanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methyl-1- Alkylphenone photoinitiators such as propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, acylphosphine oxide initiators such as 2,4,6-trimethylbenzoyl)phenylphosphine oxide, In addition to an intramolecular hydrogen abstraction type photopolymerization initiator such as methyl benzoylformate and 4-methylbenzophenone, an oxime ester photopolymerization initiator, a cationic photopolymerization initiator and the like can be mentioned. The photopolymerization initiator may be used alone or in combination of two or more.

In the pressure-sensitive adhesive sheet, the content of the photopolymerization initiator can be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the polymerizable monomer M. Regarding the content of the photopolymerization initiator, based on the crosslinkable (meth)acrylic copolymer, the content of the photopolymerization initiator is 100 parts by weight per 100 parts by weight of the crosslinkable (meth)acrylic copolymer. The amount may be 05 to 5 parts by mass.

<Adhesive layer>
As described above, the pressure-sensitive adhesive layer forming the pressure-sensitive adhesive sheet contains the crosslinked (meth)acrylic copolymer, the polymerizable monomer M, and the photopolymerization initiator. The pressure-sensitive adhesive layer may contain other components, for example, an antistatic agent, an antioxidant, a preservative and the like, as long as the effects of the present invention are not impaired. When the pressure-sensitive adhesive layer contains other components, the content is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably, with respect to the total mass of the adhesive layer. It can be 0.1 mass% or less.

(Method for forming adhesive layer)
The method for forming the pressure-sensitive adhesive layer is not particularly limited, and, for example, known methods can be widely applied. For example, the pressure-sensitive adhesive layer can be formed using a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition used here can contain the crosslinkable (meth)acrylic copolymer, the crosslinker, the polymerizable monomer M, and a photopolymerization initiator.

Specifically, the method for forming the pressure-sensitive adhesive layer includes a step of applying the pressure-sensitive adhesive composition on a substrate to form a coating film of the pressure-sensitive adhesive composition, and a drying treatment (curing) of the coating film. And a step of forming a pressure-sensitive adhesive layer.

The method for preparing the pressure-sensitive adhesive composition is not particularly limited, and the crosslinkable (meth)acrylic copolymer, the crosslinker, the polymerizable monomer M, and the photopolymerization initiator are mixed in a predetermined mixing ratio. It can be prepared by mixing. The mixing method is not particularly limited, and for example, a commercially available mixer can be used.

In the pressure-sensitive adhesive composition, the contents of the crosslinkable (meth)acrylic copolymer, the crosslinking agent, the polymerizable monomer M, and the photopolymerization initiator are appropriately set according to the target pressure-sensitive adhesive sheet. can do. Specifically, the pressure-sensitive adhesive composition so that the contents of the crosslinked (meth)acrylic copolymer, the polymerizable monomer M and the photopolymerization initiator contained in the pressure-sensitive adhesive sheet fall within the ranges described above, respectively. The content of each component contained in can be adjusted.

The pressure-sensitive adhesive composition may contain a solvent, if necessary, for improving the coating property. The solvent is not particularly limited, and examples thereof include ester compounds such as methyl acetate and ethyl acetate; ether compounds such as diethyl ether; ketone compounds such as acetone and methyl ethyl ketone; aliphatic hydrocarbons such as hexane and heptane; alicyclic rings such as cyclohexane. Formula hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene; chlorinated hydrocarbons such as chloroform and 1,2-dichloroethane; alcohols such as methanol, ethanol, isopropyl alcohol and t-butanol. The solvent can be used alone or as a mixture of two or more kinds.

When the pressure-sensitive adhesive composition contains a solvent, it is preferable to use the solvent in consideration of coatability so that the solid content concentration of the pressure-sensitive adhesive composition is in the range of 10 to 60% by mass. It is more preferable to use the solvent so as to be in the range of mass%.

The method of applying the pressure-sensitive adhesive composition onto the substrate is not particularly limited, and, for example, known application methods can be widely adopted. For example, the adhesive composition is applied using a commercially available coating device such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater. be able to.

The coating amount of the pressure-sensitive adhesive composition is not particularly limited and can be appropriately set according to the thickness of the pressure-sensitive adhesive layer of the target pressure-sensitive adhesive sheet. For example, the coating amount of the pressure-sensitive adhesive composition can be adjusted so that the thickness of the pressure-sensitive adhesive layer formed after the drying treatment described below is 5 to 1000 μm.

The type of base material for applying the pressure-sensitive adhesive composition is not particularly limited, and base materials used for forming the pressure-sensitive adhesive layer can be widely used. For example, a release sheet can be mentioned as a base material for applying the pressure-sensitive adhesive composition.

The release sheet may be, for example, a so-called separator used to protect the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet. More specifically, examples of the release sheet include a resin film having a release layer.

In the release sheet, examples of the resin film include polyethylene terephthalate film.

The release layer is a layer formed on at least one surface of the resin film, has a peeling force smaller than the adhesive force of the pressure-sensitive adhesive layer, and is formed so that the release sheet can be easily peeled off. It means that it is a layer. For such a release layer, for example, known components used as a release layer in an adhesive sheet can be widely applied. For example, the release layer can be formed of a known silicone material.

When the release sheet is used as the base material, the pressure-sensitive adhesive composition can be applied to the release layer surface of the release sheet to form a coating film of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition is applied onto the base material such as the release sheet to form a coating film, and then dried to form the pressure-sensitive adhesive layer on the base material. By this drying treatment, the reaction between the crosslinkable (meth)acrylic copolymer contained in the pressure-sensitive adhesive composition and the crosslinker proceeds, and the crosslinkable (meth)acrylic copolymer is crosslinked with the crosslinker. The crosslinked (meth)acrylic copolymer is formed.

The conditions of the drying treatment are not particularly limited, and, for example, a conventional method of drying the coating film of the pressure-sensitive adhesive composition can be widely adopted. Such a drying process can be performed using, for example, a known heating device. The heating temperature can be, for example, 50 to 200° C., and preferably 60 to 150° C. The heating time may be set so that the solvent volatilizes and the residual solvent concentration of the pressure-sensitive adhesive layer becomes, for example, 1000 ppm or less, and within the above temperature range depending on the concentration of the pressure-sensitive adhesive composition, the desired thickness of the pressure-sensitive adhesive layer, and the like. It is preferable to set it appropriately within a time of about 1 to 30 minutes.

By the above drying treatment, a pressure-sensitive adhesive layer containing the crosslinked (meth)acrylic copolymer, the polymerizable monomer M, and a photopolymerization initiator is formed. That is, in the drying treatment, the crosslinking reaction of the crosslinkable (meth)acrylic copolymer mainly progresses and the curing proceeds, but the polymerizable monomer M is in a state where the polymerization has not yet occurred. In other words, it can be said that the pressure-sensitive adhesive layer is a semi-cured state of the pressure-sensitive adhesive composition. As a reminder, the crosslinking reaction of the crosslinkable (meth)acrylic copolymer is not necessarily completed by the drying treatment, and the crosslinking reaction may proceed even by the aging treatment described later.

A protective layer for further protecting the adhesive layer can be attached to the adhesive layer thus formed. In this case, the protective layer is attached to the surface of the adhesive layer opposite to the base material. As the protective layer, for example, a release sheet can be used as described above. As for the release sheet as the protective layer, as in the case of the base material, a resin film having a release layer and the like can be mentioned. As the resin film, for example, a polyethylene terephthalate film and the like can be mentioned as in the above, and the release layer can be formed of, for example, a known silicone material.

When the base material and the protective layer formed on the respective surfaces of the pressure-sensitive adhesive layer are both release sheets (first release sheet and second release sheet, respectively), the release sheet as the base material (first release sheet) The release force of the release layer of the sheet) and the adhesive force of the release layer of the release sheet (second release sheet) for forming the protective layer are preferably different. That is, when the base material and the protective layer are both release sheets, it is preferable that the release sheets have different release forces. In this case, it becomes easy to selectively peel off only one of the release sheets when peeling off the release sheet, and it is easy to suppress the so-called tearing phenomenon.

A desired pressure-sensitive adhesive sheet can be obtained by forming the pressure-sensitive adhesive layer and, if necessary, forming the protective layer as described above, and then appropriately performing aging treatment. By this aging treatment, as described above, the crosslinking reaction of the crosslinkable (meth)acrylic copolymer proceeds, and the curing further proceeds.

The method of aging treatment is not particularly limited, and examples thereof include a method of allowing the pressure-sensitive adhesive sheet to stand in an atmosphere of 15 to 50°C. The aging time can be appropriately set depending on the temperature, and can be, for example, 1 to 10 days.

<Structure of adhesive sheet>
In the pressure-sensitive adhesive sheet, the thickness of the pressure-sensitive adhesive layer is not particularly limited and can be appropriately set depending on the intended use and the like. For example, when the pressure-sensitive adhesive sheet is used for bonding members such as a resin cover panel in an input device or the like, the thickness of the pressure-sensitive adhesive layer can be 5 to 1000 μm. The pressure-sensitive adhesive sheet may be either a single-sided pressure-sensitive adhesive sheet or a double-sided pressure-sensitive adhesive sheet, and is usually a double-sided pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet may be formed of only a pressure-sensitive adhesive layer, or may have other layers as necessary. The other layer can be formed on one side or both sides of the pressure-sensitive adhesive layer. Examples of the other layer include the release sheet described above. When the release sheets are formed on both surfaces of the pressure-sensitive adhesive layer, both release sheets (the first release sheet and the second release sheet) can have different release forces as described above. When the peeling forces of the two release sheets are different, for example, when peeling the release sheet, it becomes easy to selectively peel only one of the release sheets, and it is easy to suppress the phenomenon of soaking.

For example, in the above-mentioned method for forming a pressure-sensitive adhesive layer, when a release sheet is used as a base material and a release sheet is also used as a protective layer, a pressure-sensitive adhesive sheet having release sheets on both sides of the pressure-sensitive adhesive layer Directly attached adhesive sheet). In addition, after forming the pressure-sensitive adhesive layer, a release sheet may be separately provided on both surfaces of the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive sheet with a release layer.

When the pressure-sensitive adhesive sheet has a release sheet, these release sheets can have a function as a so-called separator in the pressure-sensitive adhesive sheet.

When the adhesive sheet includes a release sheet, the thickness of the release sheet is not particularly limited. For example, the thickness of the release sheet can be 20 to 300 μm, preferably 30 to 150 μm. The release sheets on both sides of the adhesive layer may have different thicknesses.

<How to use the adhesive sheet>
The pressure-sensitive adhesive sheet can be widely used for applications in which members (adherends) such as substrates and films are adhered to each other.

For example, an adhesive sheet may be interposed between a pair of adherends, and the adherends may be attached to each other to form a laminate, whereby the adherends can be attached to each other with the adhesive sheet. In particular, the durability can be maximized by irradiating the laminated body after the adherends have been stuck together with the pressure-sensitive adhesive sheet, to the active energy ray. When the pressure-sensitive adhesive sheet includes a release sheet, the pressure-sensitive adhesive sheet is interposed between the pair of adherends with the release sheet peeled off.

As described above, the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet exists in a state where the pressure-sensitive adhesive composition is in a semi-cured state. The polymerization reaction of the monomer M is caused by the photopolymerization initiator. Thereby, the curing of the pressure-sensitive adhesive layer further progresses, and the adherends are more firmly adhered to each other by the curing of the pressure-sensitive adhesive layer.

When the pressure-sensitive adhesive layer is cured, a polymer of the polymerizable monomer M (hereinafter referred to as “polymer M”) is generated in the pressure-sensitive adhesive layer. This polymer M has a structural unit derived from a cyclic ether-containing monomer and/or a chain ether-containing monomer in its structural unit, and by having this, the pressure-sensitive adhesive sheet exhibits excellent outgas resistance. .. As a result, even if a gas component (outgas) is generated from the adherend before, during, and after the polymerization reaction of the polymerizable monomer M, the pressure-sensitive adhesive layer is hardly affected by the outgas. Even after the pressure-sensitive adhesive layer is cured, bubbles, floating and peeling are unlikely to occur.

Here, examples of the active energy rays include ultraviolet rays, electron rays, visible rays, X-rays, and ion rays. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility. As the ultraviolet light source, for example, a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp, or the like can be used. As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as Cockloft-Walt type, Bande-Clough type, resonance transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type can be used.

Integrated light quantity of the active energy ray irradiation, for example, 500 ~ 5000mJ / cm ^2, preferably 1000 ~ 4000mJ / cm ^2, more preferably 1500 ~ 3000mJ / cm ^2.

The method of irradiating the active energy ray is not particularly limited, and for example, the entire surface of the laminate can be irradiated with the active energy ray. From this viewpoint, at least one of the adherends is preferably transparent. For irradiation with the active energy ray, for example, a known active energy ray irradiation device can be used.

Since the pressure-sensitive adhesive sheet has excellent outgas resistance, it can be particularly suitably used for applications where bubbles or the like are liable to be generated due to outgas from the adherend in the past.

The adhesive sheet can be used for bonding with one kind of first member selected from the group consisting of a resin plate, a resin sheet and a resin film. The first member can be obtained, for example, by a known manufacturing method, or can be obtained from a commercially available product. When the first member is a resin plate, it can be obtained, for example, by a casting method or various molding methods such as an injection molding method. The first member may be molded into various shapes other than a plate, a sheet, and a film, depending on the purpose of use of the adhesive sheet.

The thickness of the first member is not particularly limited, and can be appropriately set according to the application to which the adhesive sheet is applied. For example, when the first member is a resin plate, its thickness can usually be 1 mm or more.

The resin for forming the first member such as a resin plate is not particularly limited, and examples thereof include acrylic resin such as polymethylmethacrylate, polycarbonate resin, styrene resin such as polystyrene and the like. The resin may include two or more different types, and examples thereof include a composite material including an acrylic resin and a polycarbonate resin. Among them, the pressure-sensitive adhesive sheet is preferably used for bonding a polymethylmethacrylate resin plate and a polycarbonate resin plate, and particularly preferably used for bonding a polycarbonate resin plate. That is, when the adhesive sheet is used for bonding, one adherend can be a resin plate such as a polycarbonate resin.

Polycarbonate resin is known as a material that is more likely to generate outgas than acrylic resin. Therefore, in order to suppress the problem of outgassing, conventionally, a device such as providing a hard coat layer on the polycarbonate resin plate has been made, but when the pressure-sensitive adhesive sheet of the present invention is used, it does not have a hard coat layer. Even a polycarbonate resin plate can suppress the influence of outgas. Outgas may be generated, for example, during irradiation of the active energy ray at the time of bonding, or may be gradually generated with time after bonding.

More preferably, the adhesive sheet is used for bonding the first member and the second member together. The second member is not particularly limited, and is preferably used for bonding with, for example, one kind of second member selected from the group consisting of a glass plate, a resin plate, a resin sheet and a resin film.

Since the pressure-sensitive adhesive sheet has excellent outgas resistance and is particularly suitable for bonding with a polycarbonate resin plate as an adherend, it is suitable for use in display devices such as liquid crystal displays (LCD) and input devices such as touch panels. It can be used particularly preferably. As a constituent member of the touch panel, for example, 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 polymer film is coated with a conductive polymer , Hard coat film, anti-fingerprint film and the like. Examples of constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device.

2. Laminated body The laminated body of the present invention comprises the above-mentioned pressure-sensitive adhesive sheet or a cured product thereof. Strictly speaking, the laminate of the present invention comprises an adhesive layer or a cured product thereof. When the pressure-sensitive adhesive sheet includes a release sheet, the release sheet is present in the laminated body in a peeled state. That is, it can be said that the laminate has the pressure-sensitive adhesive layer.

In the laminate, if the pressure-sensitive adhesive layer is in the semi-cured state as described above (that is, when the polymerizable monomer M is present in the pressure-sensitive adhesive layer), the laminate has a pressure-sensitive adhesive sheet. On the other hand, in the laminate, if the pressure-sensitive adhesive layer is further cured by irradiation with active energy rays as described above, the laminate has a cured product of the pressure-sensitive adhesive sheet.

The laminate may further include other layers in addition to the pressure-sensitive adhesive layer, and examples thereof include the first member. When the laminated body includes the first member, the laminated body has a structure in which the first member and the adhesive sheet or the layer of the cured product thereof are laminated. The first member is the same as the first member described in the section <How to use the adhesive sheet>. Therefore, examples of the first member include a polycarbonate resin plate.

In addition to the first member such as a polycarbonate resin plate, the laminated body can further include another layer, for example, a base material layer constituted by the second member. In this case, the laminated body may have a structure in which the base material layer, the adhesive sheet or the cured product thereof, and the first member are laminated in this order.

As the base material layer, an ITO substrate, a glass substrate, a metal substrate, a resin substrate, paper, cloth, non-woven fabric, etc. can be mentioned.

When the laminated body includes a cured product of a pressure-sensitive adhesive sheet, for example, a laminated body including a pre-cured pressure-sensitive adhesive sheet (that is, a pressure-sensitive adhesive layer in a semi-cured state) is manufactured, and the laminated body is irradiated with active energy rays. By doing so, a laminate including the cured product of the pressure-sensitive adhesive sheet can be obtained.

Since the laminate has excellent resistance to outgassing, it can be particularly suitably used for applications such as a display device such as a liquid crystal display (LCD) and an input device such as a touch panel.

The method for producing the laminate is not particularly limited, and for example, after the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to the adherend in a semi-cured state, the pressure-sensitive adhesive layer is post-cured by irradiation with active energy rays. Can be included. Specifically, the method for producing a laminated body includes the step 1 of laminating an adherend on at least one surface side of the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer by irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays. Step 2 of post-curing is sequentially included. That is, the method for manufacturing a laminate can include the step of forming the pressure-sensitive adhesive layer by the same method as the method for forming the pressure-sensitive adhesive layer described above.

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the modes of these examples.

(Synthesis example 1)
<Preparation of crosslinkable (meth)acrylic copolymer (a-1)>
Prepare butyl acrylate (BA) as the monomer B (monomer having no functional group exhibiting crosslinking reactivity) and 2-hydroxyethyl acrylate (2HEA) as the monomer A (monomer having functional group exhibiting crosslinking reactivity). , BA of 75% by weight and 2HEA of 25% by weight were prepared. This monomer mixture was mixed with an ethyl acetate solution of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator to obtain a mixture, which was then heated to 60°C to randomize it. By copolymerization, a crosslinkable (meth)acrylic copolymer (a-1) was obtained. The weight average molecular weight of the crosslinkable (meth)acrylic copolymer (a-1) was 580,000.

The weight average molecular weight was measured by gel permeation chromatography (GPC) and determined on the basis of polystyrene. The measurement conditions of gel permeation chromatography (GPC) are as follows.
Solvent: Tetrahydrofuran Column: Shodex KF801, KF803L, KF800L, KF800D (4 Showa Denko Co., Ltd. were connected and used)
Column temperature: 40°C
Sample concentration: 0.5% by mass
Detector: RI-2031plus (made by JASCO)
Pump: RI-2080plus (made by JASCO)
Flow rate (flow rate): 0.8 ml/min Injection volume: 10 μL
Calibration curve: Standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko KK) A calibration curve with 10 samples of Mw=1320 to 2,500,000 was used.

(Synthesis example 2-1)
With reference to the above-mentioned Patent Document 1, 60% by mass of 2-ethylhexyl acrylate (2EHA), 5% by mass of 4-acryloylmorpholine, 15% by mass of isobornyl acrylate, 5% by mass of N-vinylacetamide and 15% of 2-hydroxyethyl acrylate. % By mass was copolymerized by a solution polymerization method to prepare a crosslinkable (meth)acrylic copolymer (b-1). The molecular weight of this crosslinkable (meth)acrylic copolymer (b-1) was 510,000 in weight average molecular weight (Mw).

(Synthesis example 2-2)
According to the method described in Example 1 of Patent Document 2 described above, a crosslinkable acrylic copolymer was prepared as follows. 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 9 parts by mass of methyl methacrylate (MMA), 13 parts by mass of 2-hydroxyethyl acrylate (2HEA), initiation of radical polymerization 2,2'-azobis(2,4-dimethylvaleronitrile) was dissolved in ethyl acetate as an agent. The solution was heated to 65° C. and subjected to random copolymerization to obtain a crosslinkable acrylic copolymer (b-2). The weight average molecular weight of the crosslinkable acrylic copolymer (b-2) was 780,000.

(Example 1)
<Preparation of adhesive composition (A-1)>
To 100 parts by mass of the crosslinkable acrylic copolymer (a-1) produced in Synthesis Example 1, 0.2 part by mass of a tolylene diisocyanate compound (Coronate L-55E manufactured by Tosoh Corporation) as a crosslinking agent, a silane cup 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a ring agent, and 3-ethyl-3-oxetanylmethyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) as a cyclic ether-containing monomer. Manufactured by OXE-10), 25 parts by mass, bisphenol A ethylene oxide modified diacrylate (Aronix M211B manufactured by Toagosei Co., Ltd.) as a polyfunctional monomer, and 12 parts by mass of bis(2,4) as a photopolymerization initiator. ,6-Trimethylbenzoyl)phenylphosphine oxide (IRGACURE819, manufactured by BASF Japan Ltd.) was added in an amount of 1.0 part by mass, and ethyl acetate was added as a solvent to a solid content concentration of 35% by mass to give a semi-cured state. A pressure-sensitive adhesive composition (A-1) was obtained.

<Preparation of adhesive layer (A-1)>
Then, as a first release sheet, a polyethylene terephthalate film having a thickness of 100 μm and provided with an easily adhesive layer treated with a silicone-based release agent (heavy separator film, manufactured by Teijin DuPont Films, release-treated polyethylene terephthalate film) ) Prepared. The pressure-sensitive adhesive composition (A-1) was evenly applied to the surface of the first release sheet on the side of the easy-adhesive layer by an applicator so that the coating thickness after drying was 150 μm. After forming the coating film of the composition (A-1), the adhesive layer (A-1) is formed on the surface of the first release sheet by performing a drying treatment for 3 minutes in an air circulating constant temperature oven at 90°C. did.

Next, prepare a second release sheet (light separator film, manufactured by Teijin DuPont Films, release-treated polyethylene terephthalate film) having a thickness of 75 μm that has been subjected to a release treatment having higher release property than the first release sheet. did. This second release sheet was attached onto the pressure-sensitive adhesive layer (A-1) formed on the surface of the first release sheet. As a result, the pressure-sensitive adhesive layer (A-1) is sandwiched between the pair of release sheets having different peeling forces, and the first release sheet/the pressure-sensitive adhesive layer (A-1)/the second release sheet is peeled off. An adhesive sheet with a sheet was obtained. This pressure-sensitive adhesive sheet with a release sheet was allowed to stand for 7 days under the conditions of 23° C. and 50% relative humidity for aging treatment.

(Example 2)
A method similar to that in Example 1 except that 3-ethyl-3-oxetanylmethyl methacrylate (OXE-30, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used as the cyclic ether-containing monomer instead of 3-ethyl-3-oxetanylmethyl acrylate. A pressure-sensitive adhesive sheet with a release sheet was obtained.

(Example 3)
Instead of 25 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer, 20 parts by mass of tetrahydrofurfuryl acrylate (Biscoat #150 manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used, and bisphenol was used as a polyfunctional monomer. A A pressure-sensitive adhesive sheet with a release sheet was prepared in the same manner as in Example 1 except that 6 parts by mass of bisphenol F EO modified diacrylate (Aronix M208 manufactured by Toagosei Co., Ltd.) was used instead of 12 parts by mass of ethylene oxide modified diacrylate. Obtained.

(Example 4)
Adhesion with a release sheet in the same manner as in Example 3 except that an acrylate having a tetrahydrofurfuryl structure (Viscoat #150D, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of tetrahydrofurfuryl acrylate as the cyclic ether-containing monomer. Got the sheet.

(Example 5)
(2-Methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate as a cyclic ether-containing monomer instead of 25 parts by mass of 3-ethyl-3-oxetanyl methyl acrylate (MEDOL-10 manufactured by Osaka Organic Chemical Industry Co., Ltd.) 10 parts by mass of bisphenol A ethylene oxide-modified diacrylate as a polyfunctional monomer was used instead of 12 parts by mass of bisphenol A EO (3.8) adduct diacrylate (Osaka Organic Chemical Industry Co., Ltd., viscoat #700HV). A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that 10 parts by mass was used.

(Example 6)
Except that 10 parts by mass of cyclic trimethylolpropane formal acrylate (Biscoat #200 manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 10 parts by mass of (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate. In the same manner as in Example 5, an adhesive sheet with a release sheet was obtained.

(Example 7)
<Preparation of adhesive composition (A-2)>
To 100 parts by mass of the crosslinkable acrylic copolymer (a-1) produced in Synthesis Example 1, 0.2 parts by mass of a tolylene diisocyanate compound (Coronate L-55E manufactured by Tosoh Corporation) as a crosslinking agent, a silane cup 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403) as a ring agent, and phenoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a chain ether-containing monomer. , Biscoat #192) in an amount of 25 parts by mass, bisphenol A ethylene oxide-modified diacrylate (Aronix M211B manufactured by Toagosei Co., Ltd.) as a polyfunctional monomer in an amount of 12 parts by mass, and bis(2,4,4,4) as a photopolymerization initiator. 6-trimethylbenzoyl)phenylphosphine oxide (manufactured by BASF Japan Ltd., IRGACURE819) was added in an amount of 1.0 part by mass, and ethyl acetate was added as a solvent so that the solid content concentration was 35% by mass, to obtain a semi-cured state. An adhesive composition (A-2) was obtained.

<Preparation of adhesive layer (A-2)>
Then, as a first release sheet, a polyethylene terephthalate film having a thickness of 100 μm and provided with an easily adhesive layer treated with a silicone-based release agent (heavy separator film, manufactured by Teijin DuPont Films, release-treated polyethylene terephthalate film) ) Prepared. The pressure-sensitive adhesive composition (A-2) was uniformly applied to the surface of the first release sheet on the side of the easily adhesive layer by an applicator so that the coating thickness after drying was 150 μm. After forming a coating film of the composition (A-2), the adhesive layer (A-2) is formed on the surface of the first release sheet by performing a drying treatment for 3 minutes in an air circulating constant temperature oven at 90°C. did.

Next, prepare a second release sheet (light separator film, manufactured by Teijin DuPont Films, release-treated polyethylene terephthalate film) having a thickness of 75 μm that has been subjected to a release treatment having higher release property than the first release sheet. did. This second release sheet was attached onto the pressure-sensitive adhesive layer (A-2) formed on the surface of the first release sheet. As a result, the pressure-sensitive adhesive layer (A-2) is sandwiched between a pair of release sheets having different peeling forces, and the first release sheet/the pressure-sensitive adhesive layer (A-2)/the second release sheet is peeled off. An adhesive sheet with a sheet was obtained. This pressure-sensitive adhesive sheet with a release sheet was allowed to stand for 7 days under the conditions of 23° C. and 50% relative humidity for aging treatment.

(Example 8)
Adhesion with a release sheet in the same manner as in Example 7 except that 2-methoxyethyl acrylate (2-MTA manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of phenoxyethyl acrylate as the chain ether-containing monomer. Got the sheet.

(Example 9)
Instead of 25 parts by mass of phenoxyethyl acrylate as a chain ether-containing monomer, 20 parts by mass of 2-[2-(ethoxy)ethoxy]ethyl acrylate (Viscoat #190, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used, and a polyfunctional monomer was used. With a release sheet in the same manner as in Example 7 except that 6 parts by mass of bisphenol F EO modified diacrylate (Toagosei Co., Ltd., Aronix M208) was used as the body instead of 12 parts by mass of bisphenol A ethylene oxide modified diacrylate. An adhesive sheet was obtained.

(Example 10)
As a chain ether-containing monomer, an acrylate having a 2-[2-(ethoxy)ethoxy]ethyl structure instead of 2-[2-(ethoxy)ethoxy]ethyl acrylate (Biscoat #190D, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used. An adhesive sheet with a release sheet was obtained in the same manner as in Example 9 except that it was used.

(Example 11)
Instead of 25 parts by mass of phenoxyethyl acrylate as a chain ether-containing monomer, 10 parts by mass of methoxytriethylene glycol acrylate (Viscoat MTG manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used, and bisphenol A ethylene oxide-modified diester was used as a polyfunctional monomer. Release sheet in the same manner as in Example 7 except that 10 parts by mass of bisphenol A EO(3.8) adduct diacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., viscoat #700HV) was used instead of 12 parts by mass of acrylate. A pressure-sensitive adhesive sheet was obtained.

(Example 12)
A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 11 except that 10 parts by mass of methoxypolyethylene glycol acrylate (manufactured by Osaka Organic Chemical Industry, biscoat MPE400A) was used instead of 10 parts by mass of methoxytriethylene glycol acrylate. ..

(Comparative Example 1)
A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that the monofunctional monomer having a cyclic ether structure, the polyfunctional monomer and the photopolymerization initiator were not used.

(Comparative example 2)
A pressure-sensitive adhesive sheet with a release sheet in the same manner as in Example 1 except that isostearyl acrylate (ISTA manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 3-ethyl-3-oxetanylmethyl acrylate as the monofunctional monomer. Got

(Comparative example 3)
0.15 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., BHS8515) as a crosslinking agent based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer (b-1) produced in Synthesis Example 2-1. Parts and 0.30 part by mass of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent so that the solid content concentration becomes 35% by mass. Methyl ethyl ketone was added as a solvent to obtain an adhesive composition (B-1). Then, the pressure-sensitive adhesive layer of Example 1 except that the pressure-sensitive adhesive composition (A-1) was changed to the pressure-sensitive adhesive composition (B-1) in the method for producing the pressure-sensitive adhesive layer (A-1) of Example 1. A pressure-sensitive adhesive sheet with a release sheet was obtained by the same procedure as the production method of (A-1). This pressure-sensitive adhesive sheet with a release sheet had a pressure-sensitive adhesive layer (B-1).

(Comparative Example 4)
0.3 part by mass of an isocyanate cross-linking agent (Takenate D110N, manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent is added to 100 parts by mass of the cross-linkable (meth)acrylic copolymer (b-2) produced in Synthesis Example 2-2. Part, 0.2 parts by mass of a polyol (EDP-300, manufactured by ADEKA CORPORATION) obtained by adding propylene oxide to ethylenediamine as a crosslinking accelerator, and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent. KBM-403) was added in an amount of 0.15% by weight, and ethyl acetate was added as a solvent so that the solid content concentration was 30% by mass to obtain a pressure-sensitive adhesive composition (B-2). Then, in the method for producing the pressure-sensitive adhesive layer (A-1) of Example 1, the pressure-sensitive adhesive composition (A-1) was changed to the pressure-sensitive adhesive composition (B-2), and the drying treatment was performed at 60°C. The pressure-sensitive adhesive layer (A-1) of Example 1 was changed except that the drying was performed in an air-circulating constant temperature oven for 1 minute and then at 155° C. for 1 minute, and the aging treatment was changed to 23° C. for 120 hours. A pressure-sensitive adhesive sheet with a release sheet was obtained by the same procedure as the production method of (1). This pressure-sensitive adhesive sheet with a release sheet had a pressure-sensitive adhesive layer (B-2).

<Outgas resistance evaluation>
(Test Example 1-1)
Using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 12 and Comparative Example 2, the outgas resistance was evaluated as follows. In a pressure-sensitive adhesive sheet with a release sheet, a second release sheet which is a light separator film is peeled off to expose a pressure-sensitive adhesive layer, and a polycarbonate resin plate having a thickness of 1 mm is used as a first member with respect to the pressure-sensitive adhesive layer (pan made by Teijin Ltd. It was attached to a light sheet PC-1151). Next, the first release sheet, which is a heavy separator film, was peeled off, and a glass plate having a size of 100 mm×200 mm was attached to the entire surface of the exposed adhesive layer as a second member. In this way, a laminate sample composed of a polycarbonate resin plate/adhesive layer/glass plate was obtained. The laminate sample was treated in an autoclave at 40° C. and 0.5 MPa for 30 minutes, and then ultraviolet rays were irradiated from the glass plate side so that the integrated light amount was 3000 mJ/cm ^2, and a test of 100 mm×200 mm was performed. I got a sample. The test sample was placed in an environment of 85° C. and a relative humidity of 85%, and after 2 hours and 100 hours, the test sample was visually observed, and bubbles, floating, and peeling were evaluated according to the following three types of criteria. ..
⊚: No bubbles, floating, or peeling were observed after 2 hours or 100 hours.
◯: Micro bubbles were observed after 2 hours, but no bubbles, floating and peeling were observed after 100 hours.
X: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 1-2)
The same as in Test Example 1-1, except that the pressure-sensitive adhesive sheet with a release sheet prepared in Comparative Examples 1, 3 and 4 was used as the pressure-sensitive adhesive sheet with a release sheet, and the laminate sample was not irradiated with ultraviolet rays. By the way, a test sample was obtained. The test sample was visually observed, and bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 1-1.

(Test Example 2-1)
Using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 12 and Comparative Example 2, the outgas resistance was evaluated as follows. In a pressure-sensitive adhesive sheet with a release sheet, a second release sheet, which is a light separator film, is peeled off to expose the pressure-sensitive adhesive layer, and a 1 mm-thick polycarbonate resin plate with a hard coat (Mitsubishi Gas It was attached to the side of the Iupilon sheet MR-58U manufactured by Kagaku Co., Ltd. on which the hard coat layer was not attached. Next, the first release sheet, which is a heavy separator film, was peeled off, and a glass plate having a size of 100 mm×200 mm was attached to the entire surface of the exposed adhesive layer as a second member. In this way, a laminate sample composed of a polycarbonate resin plate/adhesive layer/glass plate was obtained. The laminate sample was treated in an autoclave at 40° C. and 0.5 MPa for 30 minutes, and then ultraviolet rays were irradiated from the glass plate side so that the integrated light amount was 3000 mJ/cm ^2, and a test of 100 mm×200 mm was performed. I got a sample. The test sample was placed in an environment of 85° C. and a relative humidity of 85%, and after 2 hours and 100 hours, the test sample was visually observed, and bubbles, floating, and peeling were evaluated according to the following three types of criteria. ..
⊚: No bubbles, floating, or peeling were observed after 2 hours or 100 hours.
◯: Micro bubbles were observed after 2 hours, but no bubbles, floating and peeling were observed after 100 hours.
X: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 2-2)
The same as in Test Example 2-1 except that the pressure-sensitive adhesive sheet with the release sheet prepared in Comparative Examples 1, 3 and 4 was used as the pressure-sensitive adhesive sheet with the release sheet, and the laminate sample was not irradiated with ultraviolet rays. By the way, a test sample was obtained. The test sample was visually observed, and bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 2-1.

(Test Example 3-1)
Using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 12 and Comparative Example 2, the outgas resistance was evaluated as follows. In the pressure-sensitive adhesive sheet with a release sheet, the second release sheet which is a light separator film is peeled off to expose the pressure-sensitive adhesive layer, and an ITO film having a thickness of 125 μm as a second member (made by Oike Kogyo Co., Ltd.) KB300) was attached. Next, the first release sheet, which is a heavy separator film, was peeled off, and an acrylic resin plate made of polymethylmethacrylate (PMMA) having a size of 100 mm×200 mm and a thickness of 1 mm was used as the first member for the exposed adhesive layer. (Acrylite MR-200, manufactured by Mitsubishi Rayon Co., Ltd.) was stuck on the entire surface. Thereby, a laminated body sample composed of a polymethylmethacrylate resin plate/adhesive layer/ITO film was obtained. The laminate sample was treated in an autoclave at 40° C. and 0.5 MPa for 30 minutes, and then ultraviolet rays were irradiated from the glass plate side so that the integrated light amount was 3000 mJ/cm ^2, and a test of 100 mm×200 mm was performed. I got a sample. The test sample was placed in an environment of 85° C. and a relative humidity of 85%, and after 2 hours and 100 hours, the test sample was visually observed, and bubbles, floating, and peeling were evaluated according to the following three types of criteria. ..
⊚: No bubbles, floating, or peeling were observed after 2 hours or 100 hours.
◯: Micro bubbles were observed after 2 hours, but no bubbles, floating and peeling were observed after 100 hours.
X: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 3-2)
The same as in Test Example 3-1 except that the pressure-sensitive adhesive sheet with a release sheet prepared in Comparative Examples 1, 3 and 4 was used as the pressure-sensitive adhesive sheet with a release sheet, and that the laminate sample was not irradiated with ultraviolet light. By the way, a test sample was obtained. The test sample was visually observed, and bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 3-1.

(Evaluation results)
Tables 1 and 2 show the results of evaluation of outgas resistance. From the comparison between the pressure-sensitive adhesive sheets obtained in Examples 1 to 6 and the pressure-sensitive adhesive sheets obtained in Comparative Examples 1 to 4, the pressure-sensitive adhesive sheets obtained in Examples 1 to 6 are excellent in outgas resistance, and are particularly hard coats. It was found that the polycarbonate film having no layer also has excellent outgas resistance (Table 1). Similarly, from the comparison between the pressure-sensitive adhesive sheets obtained in Examples 7 to 12 and the pressure-sensitive adhesive sheets obtained in Comparative Examples 1 to 4, the pressure-sensitive adhesive sheets obtained in Examples 7 to 12 have excellent outgas resistance, In particular, it was found that the polycarbonate film having no hard coat layer also has excellent outgas resistance (Table 2).

Claims

An adhesive sheet comprising an adhesive layer,
The pressure-sensitive adhesive layer contains a crosslinked (meth)acrylic copolymer, a polymerizable monomer having a polymerizable double bond in the molecule, and a photopolymerization initiator,
The crosslinked (meth)acrylic copolymer has a structure in which the crosslinkable (meth)acrylic copolymer is crosslinked with a crosslinking agent,
The pressure-sensitive adhesive sheet, wherein the polymerizable monomer contains at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure.
The pressure-sensitive adhesive sheet according to claim 1, wherein the monofunctional monomer having a cyclic ether structure is contained in an amount of 5 to 30 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the cyclic ether structure is a 4- to 6-membered ring.
The pressure-sensitive adhesive sheet according to claim 1, wherein the monofunctional monomer having a chain ether structure is contained in an amount of 5 to 50 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the polymerizable monomer contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule.
The pressure-sensitive adhesive sheet according to claim 5, wherein the polyfunctional monomer has a bisphenol skeleton in its molecule.
The pressure-sensitive adhesive sheet according to claim 5 or 6, wherein the polyfunctional monomer is contained in an amount of 1 to 15 parts by mass based on 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, which is used for bonding with one kind of first member selected from the group consisting of a resin plate, a resin sheet and a resin film.
The pressure-sensitive adhesive sheet according to claim 8, which is used for bonding the first member and one kind of second member selected from the group consisting of a glass plate, a resin film and a resin plate.
A laminate comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 9 or a cured product thereof.
The laminate according to claim 10, further comprising the first member, and having a structure in which the first member and a layer of the adhesive sheet or a cured product thereof are laminated.