JP7234674B2 - Adhesive sheet and laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet and a laminate comprising the pressure-sensitive 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 laminating optical members, and transparent adhesive sheets are also used for laminating display devices and input devices. .

A pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive sheet for an optical member is produced by a known polymerization method, and examples of the polymerization method include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, and the like. A pressure-sensitive adhesive sheet having a solvent-type pressure-sensitive adhesive as the pressure-sensitive adhesive layer is widely used from the viewpoint of easy production and easy production of an optically transparent pressure-sensitive adhesive sheet. Examples of solvent-type adhesives include those containing acrylic resin as a main component. Such an acrylic resin can be obtained by solution polymerization, that is, by conducting a polymerization reaction in a solvent in which an acrylic monomer is dissolved. In solution polymerization, as the polymerization progresses, the molecular weight of the polymer increases and the viscosity of the reaction solution increases. There is Therefore, in order to ensure the cohesive force necessary for the adhesive, a cross-linking agent capable of reacting with an acrylic resin, such as an isocyanate-based compound or an epoxide-based compound, is added to the adhesive composition. Such a cross-linking agent builds a cross-linked network by reacting with the acrylic resin over time, and increases the cohesive strength of the pressure-sensitive adhesive layer.

In addition, as a method for forming an adhesive sheet for optical members, a method of curing by two-stage polymerization in which polymerization is performed by heat (or active energy rays) and then polymerization by active energy rays (or heat) is sometimes used. be. Since such a pressure-sensitive adhesive sheet is formed from, for example, a pressure-sensitive adhesive composition having both thermosetting and active energy ray-curing properties (hereinafter also referred to as a “dual-curable pressure-sensitive adhesive composition”), the thermosetting and has active energy ray curability. For this reason, before lamination with the adherend, temporary adhesion can be achieved, for example, by performing only heat curing, and then further curing with active energy rays (referred to as post-curing or after-curing). Can strongly adhere to the adherend.

For example, in Patent Document 1, a base polymer (A) containing a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer unit (a2) having a crosslinkable functional group, and a lauryl acrylate (b1) a monomer (B) containing a monomer (B), a crosslinking agent (C) that reacts with the base polymer (A) by heat, and a polymerization initiator (D ) and a solvent (E), and a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer obtained by semi-curing the pressure-sensitive adhesive composition by heating. Further, Patent Document 2 discloses a pressure-sensitive adhesive sheet having at least one UV-curable pressure-sensitive adhesive layer.

JP 2016-084391 A JP 2012-031059 A

However, when the present inventors examined the properties of the pressure-sensitive adhesive sheets described in Patent Documents 1 and 2, there were cases where the substrate adhesion and durability were insufficient. It has been found that there are cases where sufficient adhesion to and durability cannot be obtained. In addition, the workability after curing was sometimes insufficient, and there was room for improvement.

The present invention has been made in view of the above, and a pressure-sensitive adhesive sheet that can exhibit excellent adhesion to a substrate and durability even under high-temperature and high-humidity conditions and that is also excellent in workability, and the pressure-sensitive adhesive sheet. An object of the present invention is to provide a laminate provided with an adhesive sheet.

The present inventors have conducted intensive research to achieve the above object, and found that a monofunctional monomer having a cyclic ether structure is used, and the constant load peel distance and probe tack value are within a specific range. The present inventors have found that the above objects can be achieved by the above-mentioned methods, and have completed the present invention.

That is, the present invention includes, for example, the subject matter described in the following sections.
Item 1
A pressure-sensitive adhesive sheet comprising a pressure-sensitive 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 a crosslinkable (meth)acrylic copolymer having an acid group is crosslinked with a crosslinking agent,
The polymerizable monomer contains a monofunctional monomer having a cyclic ether structure,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer satisfies the following physical properties (1) and (2) when the pressure-sensitive adhesive layer is irradiated with an active energy ray so that the integrated light amount is 3000 mJ/cm ² and post-cured.
Physical properties (1): i) 85° C., 85% relative humidity, and ii) 85° C., less than 10% relative humidity, each constant load peel distance measured under the following (measurement conditions) is 50 mm or less:
Physical property (2): Probe tack value is 1.5 N/5 mmφ or less;
(Measurement condition)
A 25 mm wide and 75 mm long area of the adhesive surface of the adhesive layer having a size of 25 mm wide and 100 mm long is attached to an adherend and post-cured. i) 85° C., 85% relative humidity, and ii) 85° C., relative humidity of less than 10%. . A load of 100 g was applied to the end of the non-bonded area of the pressure-sensitive adhesive layer in the length direction for 5 minutes. and ii) measured as each constant load peel distance at 85°C and less than 10% relative humidity.
Item 2
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 50 parts by mass with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
Item 3
Item 3. The adhesive sheet according to Item 1 or 2, wherein the cyclic ether structure is a 4- to 6-membered ring.
Item 4
4. The pressure-sensitive adhesive sheet according to any one of Items 1 to 3, wherein the polymerizable monomer contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule.
Item 5
Item 5. The pressure-sensitive adhesive sheet according to item 4, wherein the polyfunctional monomer has a bisphenol skeleton in the molecule.
Item 6
Item 6. The pressure-sensitive adhesive sheet according to Item 4 or 5, wherein the polyfunctional monomer is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer.
Item 7
The adhesive layer has a gel fraction of 10 to 70%,
The adhesive layer after the post-curing has a gel fraction of 60 to 100%, and the gel fraction of the adhesive layer after the post-curing is higher than the gel fraction of the adhesive layer before the post-curing. Item 7. The pressure-sensitive adhesive sheet according to any one of items 1 to 6, which also has a higher viscosity of 10% or more.
Item 8
A laminate comprising the pressure-sensitive adhesive sheet according to any one of Items 1 to 7 or a cured product thereof.
Item 9
A step of laminating an adherend on at least one side of the pressure-sensitive adhesive sheet according to any one of Items 1 to 7, and irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with an active energy ray to remove the pressure-sensitive adhesive layer. A method for producing a laminate, comprising in order a step of curing.

The pressure-sensitive adhesive sheet according to the present invention can exhibit excellent adhesion to substrates and durability even under high-temperature and high-humidity conditions, and is also excellent in workability.

BRIEF DESCRIPTION OF THE DRAWINGS It is an example of embodiment of the adhesive sheet of this invention, and is the schematic showing the cross section. It is an example of embodiment of the laminated body of this invention, and is the schematic showing the cross section. It is another example of the laminated body of this invention, and is the schematic showing the cross section. It is a figure explaining the measuring method of constant-load peeling distance.

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 Sheet The adhesive sheet of the present invention has 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 combination has a structure in which a crosslinkable (meth)acrylic copolymer having an acid group is crosslinked with a crosslinking agent, and the polymerizable monomer includes a monofunctional monomer having a cyclic ether structure.

Furthermore, in the pressure-sensitive adhesive sheet of the present invention, when the pressure-sensitive adhesive layer is irradiated with an active energy ray so that the integrated light amount is 3000 mJ/cm ² and post-cured, the pressure-sensitive adhesive layer has the following physical properties (1) and (2). ).
Physical properties (1): i) 85° C., 85% relative humidity, and ii) 85° C., less than 10% relative humidity, each constant load peel distance measured under the following (measurement conditions) is 50 mm or less:
Physical property (2): Probe tack value is 1.5 N/5 mmφ or less;
In physical properties (1), the constant load peel distance under the condition i) indicates the high temperature and high humidity substrate adhesion, and the constant load peel distance under the condition ii) indicates the high temperature substrate adhesion. The details of the method for measuring the constant load peel distance and the probe tack value will be described in the Examples section below.

As used herein, "(meth)acryl" means "acryl" or "methacryl", and "(meth)acrylate" means "acrylate" or "methacrylate".

<Crosslinked (meth)acrylic copolymer>
A crosslinked (meth)acrylic copolymer is a polymer having a crosslinked structure formed by reacting a crosslinkable (meth)acrylic copolymer having an acid group with a crosslinking agent. As such a crosslinked (meth)acrylic copolymer, for example, a wide range of known crosslinked (meth)acrylic copolymers used in adhesive sheets can be applied.

(Crosslinkable (meth)acrylic copolymer)
A crosslinkable (meth)acrylic copolymer having an acid group can have a structure in which an acid group is bonded to a (meth)acrylic copolymer skeleton. Since the crosslinkable (meth)acrylic copolymer has an acid group, it becomes possible to react with a crosslinker and form a crosslinked (meth)acrylic copolymer. In addition, since the crosslinkable (meth)acrylic copolymer has an acid group, the pressure-sensitive adhesive sheet tends to have improved adhesion to the substrate and durability, and tends to have good workability.

In the crosslinkable (meth)acrylic copolymer, the acid group is not particularly limited, and examples thereof include a carboxy group and a sulfonic acid group. preferable. That is, the crosslinkable (meth)acrylic copolymer preferably has a carboxy group.

A crosslinkable (meth)acrylic copolymer having an acid group can also have a functional group exhibiting crosslinkability other than the acid group. Functional groups other than acid groups that exhibit cross-linking reactivity are not particularly limited, and examples thereof include hydroxyl groups, amino groups, amide groups, epoxy groups, thiol groups, and isocyanate groups.

The crosslinkable (meth)acrylic copolymer can have, for example, a monomer unit having an acid group and a monomer unit having no functional group exhibiting crosslinkability. In this case, the crosslinkable (meth)acrylic copolymer having an acid group can be obtained, for example, by copolymerizing a monomer having an acid group and a monomer having no functional group exhibiting crosslinkability. . Hereinafter, a monomer having an acid group is referred to as "monomer A", and a monomer having no functional group exhibiting cross-linking reactivity is referred to as "monomer B".

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

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.

Examples of the monomer B include (meth)acrylates having linear, branched or cyclic alkyl groups, or (meth)acrylates having an aromatic ring. 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. 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) Alkyl (meth)acrylates such as acrylates are preferred. In this case, it is easy to obtain a pressure-sensitive adhesive sheet excellent in substrate adhesion, durability and workability. Monomer B can be used alone or in combination of two or more different types.

A crosslinkable (meth)acrylic copolymer can be produced, for example, by polymerizing a monomer A and a 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 the polymerization for obtaining the crosslinkable (meth)acrylic copolymer, the proportion of the monomer A and the monomer B used is not particularly limited, and can be appropriately set according to the desired crosslinkable (meth)acrylic copolymer. can. For example, 0.5 to 60 parts by mass of the monomer A (monomer having an acid 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 adhesive strength, and deterioration of substrate adhesion, durability, and workability is unlikely to occur. It is preferable that the monomer A is contained in an amount of 1 to 55 parts by mass 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, polymerizable monomers other than the monomers A and B can be used in combination, if necessary. Examples of such polymerizable monomers include radically polymerizable monomers copolymerizable with monomer A and monomer B. The amount of the radically polymerizable monomer copolymerizable with Monomer A and Monomer B is preferably 20 parts by mass or less per 100 parts by mass of the total amount of Monomer A and Monomer B, for example.

Examples of radically polymerizable monomers copolymerizable with the monomers A and B include hydroxyl group-containing (meth)acrylic monomers, vinyl acetate and styrene.

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 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 the production of the crosslinkable (meth)acrylic copolymer, the proportion (mass ratio) of the monomers A and B used is included in the crosslinkable (meth)acrylic copolymer obtained by the polymerization of the monomers A and B. It corresponds to the mass ratio of a monomer unit having a functional group exhibiting cross-linking reactivity and a monomer unit having no functional group exhibiting cross-linking reactivity.

A solvent may optionally be used in the polymerization method for obtaining the crosslinkable (meth)acrylic copolymer. 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.

In the polymerization method for obtaining a crosslinkable (meth)acrylic copolymer, a polymerization initiator can be used as necessary. can do. 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 concentration of the polymerization initiator is not particularly limited, and can be appropriately adjusted, for example, within a range in which the resulting crosslinkable (meth)acrylic copolymer has a desired 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.

Polymerization for obtaining a crosslinkable (meth)acrylic copolymer can be carried out, for example, under an inert gas atmosphere such as nitrogen.

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

The weight average molecular weight of the crosslinkable (meth)acrylic copolymer 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 acid value of the crosslinkable (meth)acrylic polymer is preferably 1 mgKOH/g or more, more preferably 2 mgKOH/g or more, and even more preferably 3 mgKOH/g or more. The acid value of the crosslinkable (meth)acrylic polymer is preferably 200 mgKOH/g or less. In addition, in the present invention, the acid value of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is also preferably within the above range.

The acid value of the crosslinkable (meth)acrylic polymer is calculated by the following method. First, a crosslinkable (meth)acrylic polymer as a sample was precisely weighed into a 100 ml Erlenmeyer flask with a precision balance so that the solid content of the crosslinkable (meth)acrylic polymer was about 2 g, and toluene/2-propanol/water=5/5/0 was added to this. Add 10 ml of a mixed solvent of .5 (weight ratio) and dissolve. Then, 1 to 3 drops of p-naphtholbenzene solution is added as an indicator to the container, and thoroughly stirred until the sample becomes uniform. This is titrated with a 0.1N potassium hydroxide-2-propanol solution, and the end point of neutralization is when the light red color of the indicator continues for 30 seconds. From the results, the following calculation formula Acid value (mgKOH / g) = [cKOH × (V1-V0) × 5.611] / S
The value obtained using is taken as the acid value of the sample. In the above formula, cKOH is the molar concentration (mol/L) of 0.1N potassium hydroxide-2-propanol solution, and V1 is the 0.1 mol/L potassium hydroxide-2-propanol solution required for titration of the sample. is the amount (mL), V0 is the amount (mL) of 0.1 mol/L potassium hydroxide-2-propanol solution required for blank titration, and S is the sample collection amount (g). .

Crosslinkable (meth)acrylic copolymers are so-called random copolymers in which monomer units having crosslinkable functional groups and monomer units not having crosslinkable functional groups are randomly arranged. It can be a polymer. Alternatively, the crosslinkable (meth)acrylic copolymer can have other structures such as block polymers.

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

The type of cross-linking agent is not particularly limited, and a wide range of known cross-linking agents can be used. Examples of cross-linking agents include 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.

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.

In obtaining a crosslinked (meth)acrylic copolymer by crosslinking the crosslinkable (meth)acrylic copolymer with a crosslinking agent, the 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 cross-linking agent can be used per 100 parts by mass of the crosslinkable (meth)acrylic copolymer. In this case, the adhesive sheet can have desired adhesive strength. It is preferable to use 0.05 to 1 part by mass of the cross-linking 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 such other components include silane coupling agents. When a silane coupling agent is used together, 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, a wide range of known compounds can be used. Silane coupling agents include, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyldialkoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxysilane. Propyltriacoxysilane γ-methacryloxypropyltrialkoxysilane, γ-chloropropyltrialkoxysilane, γ-methacryloxypropyldialkoxysilane, γ-mercaptopropyltrialkoxysilane, vinyltrialkoxysilane and the like.

When a silane coupling agent is used in combination in cross-linking the cross-linkable (meth)acrylic copolymer with a cross-linking agent, the amount used is from 0.1 to 0.1 per 100 parts by mass of the cross-linkable (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 its molecule includes a monofunctional monomer having a cyclic ether structure. A monofunctional monomer having a cyclic ether structure is a monomer having both a polymerizable double bond and a cyclic ether structure in its molecule. Hereinafter, a polymerizable monomer having a polymerizable double bond in the molecule is referred to as "polymerizable monomer M", and a monofunctional monomer having a cyclic ether structure is referred to as "cyclic ether-containing monomer". do.

(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 widely known cyclic ether-containing monomers are used. be able to. For example, a cyclic ether-containing monomer can have groups containing cyclic ether structures in side chains.

The cyclic ether structure is not particularly limited as long as it is a 3-membered ring or more, but from the viewpoint of easily improving substrate adhesion, durability and workability, the cyclic ether structure is preferably a 4-membered ring or more. more preferred. That is, the cyclic ether structure is preferably other than a three-membered ring. Among them, the cyclic ether structure is preferably a 4- to 6-membered ring, that is, one or more of a 4-membered ring, a 5-membered ring and a 6-membered ring.

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

The cyclic ether structure is preferably a tetrahydrofuran structure. In this case, the pressure-sensitive adhesive sheet is particularly improved in substrate adhesion, durability and workability.

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 the like. Examples include methyl group, ethyl group, n-propyl group and i-propyl group.

When the cyclic ether structure has the above substituents, the number of substituents, bonding positions, etc. are not particularly limited, and the effect of the present invention is not impaired in any case. Usually, the number of substituents that the cyclic ether structure has is one or two.

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

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

Further specific examples of the cyclic ether-containing monomer include the compounds represented by (3-1) to (3-6) below.

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

The content of the cyclic ether-containing monomer in the adhesive sheet is not particularly limited. From the viewpoint of improving the adhesion to the substrate, durability and workability of the adhesive sheet, the cyclic ether-containing monomer (monofunctional monomer having a cyclic ether structure) in the adhesive sheet is the crosslinkable (meth)acrylic co- It is preferably contained in an amount of 5 to 50 parts by mass with respect to 100 parts by mass of the polymer.

More specifically, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer is more preferably contained in an amount of 3 parts by mass or more with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer, and may be contained in an amount of 7 parts by mass or more. Especially preferred. Moreover, in the adhesive sheet, the cyclic ether-containing monomer is more preferably contained in an amount of 32 parts by mass or less, particularly preferably 27 parts by mass or less, relative to 100 parts by mass of the crosslinkable (meth)acrylic copolymer.

Since the pressure-sensitive adhesive sheet contains a monofunctional monomer having a cyclic ether structure, the pressure-sensitive adhesive sheet has improved adhesion to the substrate, and also has good hardness after curing. As a result, the pressure-sensitive adhesive sheet has superior adhesion to the substrate, durability and workability.

The polymerizable monomer M can also contain monofunctional polymerizable monomers other than cyclic ether-containing monomers, as long as the effects of the present invention are not impaired. As such a monofunctional polymerizable monomer, for example, a wide range of known monofunctional polymerizable monomers can be applied. When the polymerizable monomer M contains a monofunctional polymerizable monomer other than a cyclic ether-containing monomer, the content thereof is, for example, 10% by mass or less with respect to the total mass of the polymerizable monomer M, preferably It 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 its molecule. In this case, the pressure-sensitive adhesive sheet can be easily improved in substrate adhesion, durability, and workability, and can also suppress shrinkage when the pressure-sensitive adhesive sheet is cured. A polyfunctional monomer having two or more polymerizable double bonds in the molecule is hereinafter simply referred to as a "polyfunctional monomer".

The type of polyfunctional monomer is not particularly limited, and for example, a wide range of known polyfunctional monomers used in adhesive sheets can be used. Among them, the polyfunctional monomer can more effectively increase the hardness of the adhesive layer when the adhesive sheet is cured (after post-curing) and easily improve the workability of the adhesive sheet. It preferably has a bisphenol skeleton in the molecule. More specifically, an alkylene oxide-modified (meth)acrylic ester having a bisphenol skeleton can be used as the polyfunctional monomer. In this case, the alkylene oxide is, for example, ethylene oxide, propylene oxide and the like. The number of alkylene oxide units can be, for example, 1-5.

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

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

Commercially available polyfunctional monomers can also be used, for example, trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) manufactured by Toagosei Co., Ltd. Bifunctional monomer M211B (bisphenol A EO-modified diacrylate) manufactured by Toagosei Co., Ltd., and the like can be mentioned.

The number of polymerizable double bonds in one molecule of the polyfunctional monomer is not particularly limited as long as it is two or more. For example, in the polyfunctional monomer, the number of polymerizable double bonds in one molecule can be 2 or more and 5 or less, preferably 2 or more and 5 or less, and 2 or 3 is particularly preferred.

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

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

The polymerizable monomer M can be composed only of a monofunctional monomer and a polyfunctional monomer, or can be composed only of a cyclic ether-containing monomer and a polyfunctional monomer.

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

Examples of photopolymerization initiators include, but are not limited to, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenylketone, 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 photopolymerization initiators such as propanone, acylphosphine oxide polymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl)phenylphosphine oxide, In addition to intramolecular hydrogen abstraction type photopolymerization initiators such as methyl benzoylformate and 4-methylbenzophenone, oxime ester photopolymerization initiators and cationic photopolymerization initiators can be used. A photoinitiator may use only 1 type and can also use 2 or more types together.

In the 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, if the crosslinkable (meth)acrylic copolymer is used as a standard, the content of the photopolymerization initiator per 100 parts by mass of the crosslinkable (meth)acrylic copolymer is 0.5 parts by mass. 05 to 5 parts by mass.

<Adhesive layer>
As described above, the pressure-sensitive adhesive layer constituting 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 such as antistatic agents, antioxidants, preservatives, etc., as long as the effects of the present invention are not impaired. When the pressure-sensitive adhesive layer contains other components, the content thereof is, for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, particularly preferably 1% by mass or less, based on the total mass of the adhesive layer It can be 0.1% by mass or less.

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

Specifically, the adhesive layer is formed by applying the adhesive composition to a substrate to form a coating film of the adhesive composition, and drying (curing) the coating film. , a step of forming an adhesive layer.

The preparation method of 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 added at a predetermined mixing ratio. It can be prepared by mixing. The mixing method is also not particularly limited, and for example, a commercially available mixer can be used.

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

The pressure-sensitive adhesive composition may also contain a solvent as necessary, for example, in order to improve coatability. 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; 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. A solvent can be used individually or as a mixture of 2 or more types.

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

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

The coating amount of the adhesive composition is not particularly limited, and can be appropriately set according to the thickness of the adhesive layer of the intended 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 also not particularly limited, and a wide range of base materials used for forming the pressure-sensitive adhesive layer can be used. For example, a release sheet can be mentioned as a base material for applying the pressure-sensitive adhesive composition.

As the release sheet, for example, a so-called separator used for protecting the adhesive layer in a pressure-sensitive adhesive sheet can be used. More specifically, the release sheet may include a resin film having a release layer.

Examples of the resin film in the release sheet include a polyethylene terephthalate film.

The release layer is a layer formed on at least one side of the resin film, and has a release force smaller than the adhesive force of the adhesive layer, and is formed so that the release sheet can be easily peeled off. layer. For such a release layer, for example, a wide range of known components that are used as a release layer in pressure-sensitive adhesive sheets can be applied. For example, a known silicone material can be used to form the release layer.

When the release sheet is used as the substrate, 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.

After coating the pressure-sensitive adhesive composition on a base material such as the release sheet to form a coating film, a drying process is performed to form a 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 for the drying treatment are not particularly limited, and for example, a wide range of conventional drying methods for coating films of pressure-sensitive adhesive compositions can be employed. Such drying treatment can be performed using, for example, a known heating device. The heating temperature can be, for example, 50 to 200.degree. C., preferably 60 to 150.degree. The heating time may be set so that the solvent volatilizes and the residual solvent concentration in the adhesive layer is, for example, 1000 ppm or less. It is preferable to appropriately set the time within about 1 to 30 minutes.

By the drying treatment, an adhesive layer containing the crosslinked (meth)acrylic copolymer, the polymerizable monomer M, and the photopolymerization initiator is formed. In other words, in the drying process, the cross-linking reaction of the cross-linkable (meth)acrylic copolymer mainly progresses and the curing progresses, but the polymerizable monomer M has not yet been polymerized. In other words, it can be said that the pressure-sensitive adhesive layer is in a state in which the pressure-sensitive adhesive composition is semi-cured. As a reminder, the cross-linking reaction of the cross-linkable (meth)acrylic copolymer is not necessarily completed by the drying treatment, and the cross-linking reaction may proceed even by the aging treatment described below.

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

When both the substrate and the protective layer are release sheets (first release sheet and second release sheet, respectively), the release force of the release layer of the release sheet (first release sheet) as the substrate, It is preferably different from the adhesive strength of the release layer of the release sheet (second release sheet) for forming the protective layer. In other words, when both the substrate and the protective layer are release sheets, it is preferable that the release sheets have different release forces. In this case, when peeling off the release sheets, it becomes easy to selectively peel off only one of the release sheets, and it is easy to suppress the phenomenon of so-called separation.

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

The method of aging treatment is not particularly limited, and for example, a method of leaving the pressure-sensitive adhesive sheet in an atmosphere of 15 to 50° C. can be mentioned. 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 according to the intended use. For example, the thickness of the adhesive layer can be 5 to 1000 μm.

The pressure-sensitive adhesive sheet may be formed of only the pressure-sensitive adhesive layer, or may have other layers as necessary. Other layers can be formed on one side or both sides of the adhesive layer. Other layers include the aforementioned release sheet. When release sheets are formed on both sides of the pressure-sensitive adhesive layer, as described above, both release sheets (first release sheet and second release sheet) can have different release forces. When the two release sheets have different peel strengths, for example, when peeling off the release sheets, it becomes easier to selectively peel off only one of the release sheets, and the phenomenon of so-called separation can be easily suppressed.

For example, in the above-described method for forming an adhesive layer, when a release sheet is used as the base material and a release sheet is used as the protective layer, an adhesive sheet having release sheets on both sides of the adhesive layer (release layer You can directly get the adhesive sheet with After forming the pressure-sensitive adhesive layer, separate release sheets may be provided on both sides of the layer to obtain a pressure-sensitive adhesive sheet with a release layer.

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

When the pressure-sensitive 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 20-300 μm, preferably 30-150 μm. The release sheets on both sides of the pressure-sensitive adhesive layer may have different thicknesses.

FIG. 1 is an example of an embodiment of a pressure-sensitive adhesive sheet, and is a schematic cross-sectional view. As shown in FIG. 1, the pressure-sensitive adhesive sheet can have a transparent substrate 12a on one side of the pressure-sensitive adhesive layer 11 . In this case, the other surface of the adhesive layer 11 is preferably covered with a release sheet 12b. When an adhesive sheet is used, the release sheet 12b is peeled off and the adhesive layer 11 is adhered to the desired adherend so that the adhesive layer 11 is adhered to the desired adherend. It is preferable to 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.

The pressure-sensitive adhesive sheet can also have release sheets on both surfaces thereof. When release sheets are provided on both surfaces of the adhesive sheet, it is preferable to have release sheets 12a and 12b on both surfaces of the adhesive layer 11 as shown in FIG.

<Physical properties of adhesive sheet>
As described above, the pressure-sensitive adhesive sheet of the present invention satisfies physical properties (1) and physical properties 2 when post-curing by irradiating the pressure-sensitive adhesive layer with an active energy ray so that the integrated light amount is 3000 mJ/cm ² . . When the pressure-sensitive adhesive sheet satisfies the physical properties (1) and (2) above, the cured pressure-sensitive adhesive sheet has excellent substrate adhesion, durability and workability.

(Physical properties (1))
The measurement conditions for physical property (1) (constant load peel distance) are as follows.
(Measurement condition)
A 25 mm wide and 75 mm long area of the adhesive surface of the adhesive layer having a size of 25 mm wide and 100 mm long is attached to an adherend and post-cured. i) 85° C., 85% relative humidity, and ii) 85° C., relative humidity of less than 10%. . A load of 100 g was applied to the end of the non-bonded area of the pressure-sensitive adhesive layer in the length direction for 5 minutes. and ii) measured as each constant load peel distance at 85°C and less than 10% relative humidity.

Specifically, first, a test piece for measurement is produced by the following method. A triacetyl cellulose film (Fuji Tac TD60UL, thickness 60 μm, manufactured by Fuji Film Co., Ltd.) is pasted on one side of the pressure-sensitive adhesive layer using a hand roller to prepare a laminated film. This laminated film is cut into a size of 25 mm in width and 100 mm in length, and then a 25 mm in width and 75 mm in length of the adhesive surface on the other side of the adhesive layer is cut into an adherend ( Polycarbonate plate with hard coat layer: Iupilon MR58 (thickness 1 mm, manufactured by Mitsubishi Gas Chemical Co., Ltd.) is attached to the hard coat surface side using a 2-kg compression roller. This state is maintained in an autoclave at 40° C. and 5 atm for 30 minutes to adhere to the adherend.

Under the above measurement conditions, the post-curing is performed by irradiating ultraviolet rays from the triacetyl cellulose film side of the test piece for measurement so that the cumulative amount of light is 3000 mJ/cm ² .

After that, after leaving for 24 hours in an environment of i) 85°C, 85% relative humidity, and ii) 85°C, relative humidity of less than 10%, i) 85°C, 85% relative humidity, and ii) 85°C, Under an environment with a relative humidity of less than 10%, a weight 34 of 100 g was hung from the longitudinal end of the non-bonding region (width 25 mm, length 25 mm) of the laminated film as shown in FIG. A load of 100 g is applied in the direction of 90° to the surface, and left in that state for an additional 5 minutes. The length L (constant load peeling distance) of the portion where the laminated film was peeled during that time is measured.

i) The constant load peel distance at 85° C. and 85% relative humidity measured under the above measurement conditions is 50 mm or less, preferably 45 mm or less, more preferably 40 mm or less, and 35 mm or less. is more preferable, and 30 mm or less is particularly preferable. Further, ii) the constant load peel distance at 85° C. and a relative humidity of less than 10% is 50 mm or less, preferably 45 mm or less, more preferably 40 mm or less, and even more preferably 35 mm or less, 30 mm or less is particularly preferred. The constant load peel distance at i) 85° C., 85% relative humidity and ii) 85° C., less than 10% relative humidity may be 0 mm.

(Physical properties (2))
Physical property (2) (probe tack value) is measured under the following conditions in detail. As a measuring device, "NS Probe Tack Tester" manufactured by Nichiban Co., Ltd. is used, and the probe diameter is 5 mmφ. The probe base material uses a stainless steel surface finish AA#400 polished mirror surface, and the weight is made of brass and has a weight of 19.6±0.2 g. The probe moving speed is 1.0 cm/sec, and the dwell time is 1 second.

In the measurement of the physical property (2), the post-curing is performed by irradiating ultraviolet rays from the triacetyl cellulose film side of the test piece for measurement so that the integrated light amount becomes 3000 mJ/cm ² .

In the physical property (2), the probe tack value is more preferably 1.0 N/5 mmφ or less, particularly preferably 0.5 N/5 mmφ or less, from the viewpoint that workability is particularly likely to be improved. Moreover, the lower limit of the probe tack value is not particularly limited, and for example, it is more preferably 0.01 N/5 mmφ or more, and particularly preferably 0.1 N/5 mmφ or more.

(Other physical properties)
In the pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer is 10 to 70%, the gel fraction of the pressure-sensitive adhesive layer after post-curing is 60-100%, and the pressure-sensitive adhesive layer after post-curing is It is preferable that the gel fraction is 10% or more higher than the gel fraction before post-curing. In this case, the cured pressure-sensitive adhesive sheet can have even better substrate adhesion, durability and workability.

In the pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer before post-curing is preferably 20% or more, more preferably 30% or more, and particularly preferably 40% or more. Moreover, in the adhesive sheet, the gel fraction of the adhesive layer before post-curing is more preferably 68% or less, and particularly preferably 65% or less.

In the pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer after post-curing is preferably 70% or more, more preferably 75% or more, and particularly preferably 80% or more.

In the pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer after post-curing is more preferably 15% or more higher than that before post-curing, and particularly preferably 20% or more.

<How to use the adhesive sheet (post-curing method)>
The pressure-sensitive adhesive sheet can be widely used for bonding members (adherends) such as substrates and films to each other.

For example, a pressure-sensitive adhesive sheet is interposed between a pair of adherends, the adherends are laminated with the pressure-sensitive adhesive sheet to form a laminate, and the adherends are pasted with the pressure-sensitive adhesive sheet by "post-curing". can be matched. When the adhesive sheet includes a release sheet, the adhesive sheet is interposed between the pair of adherends with the release sheet removed.

As described above, since the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet exists in a semi-cured state of the pressure-sensitive adhesive composition, post-curing causes the polymerization reaction of the polymerizable monomer M present in the pressure-sensitive adhesive layer. is caused by the photoinitiator. As a result, the curing of the pressure-sensitive adhesive layer proceeds further, and the adherends are adhered to each other more firmly due to the curing of the pressure-sensitive adhesive layer.

By post-curing the adhesive layer, a polymer of the polymerizable monomer M (hereinafter referred to as "polymer M") is generated in the adhesive layer. This polymer M has a structural unit derived from a cyclic ether-containing monomer in its structural units, and by having this, the pressure-sensitive adhesive sheet exhibits excellent substrate adhesion, durability and workability.

Here, the method for post-curing the pressure-sensitive adhesive layer is not particularly limited, and for example, a wide range of known curing methods can be employed. Specifically, the adhesive layer can be post-cured by irradiating the adhesive layer with active energy rays. It should be noted that the post-curing conditions for using the pressure-sensitive adhesive sheet in various applications are limited to the post-curing conditions for measuring the physical properties (1) and (2) described above, although this is merely a note to make sure. not to be

Examples of the active energy rays include ultraviolet rays, electron beams, visible rays, X-rays, and ion beams. 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. As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as a Cockroftwald accelerator, a Van de Clough accelerator, a resonance transformer accelerator, an insulating core transformer accelerator, a linear accelerator, a dynamitron accelerator, and a high frequency accelerator can be used.

The integrated amount of active energy ray irradiation is, for example, 500 to 5000 mJ/cm ² , preferably 1000 to 4000 mJ/cm ² , more preferably 1500 to 3000 mJ/cm ² .

The method of irradiating the active energy ray is also not particularly limited, and for example, the active energy ray can be applied to the entire surface of a laminate formed by bonding adherends together with an adhesive sheet. From this point of view, at least one of the adherends is preferably transparent. For the irradiation of active energy rays, for example, a known active energy ray irradiation device can be used.

<Application of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention is an optical member that requires durability, and is preferably used for bonding optical members that have a complicated shape and require punching after forming a laminate.

The pressure-sensitive adhesive sheet of the present invention is adhered to an adherend such as a substrate, post-cured, and has excellent substrate adhesion and durability even when exposed to a high-temperature and high-humidity environment. Therefore, it is possible to suppress the occurrence of floating and peeling. The pressure-sensitive adhesive sheet of the present invention, for example, is laminated to a polycarbonate substrate, post-cured, and then, even when exposed to a high-temperature and high-humidity environment, it is prevented from floating or peeling off from the polycarbonate substrate. can do.

The pressure-sensitive adhesive sheet of the present invention may be bonded to an optical member such as a polarizing plate. Here, the polarizing plate includes a polarizer and a polarizer protective film, and the pressure-sensitive adhesive sheet of the present invention is preferably attached to the polarizer protective film. Polarizer protective films include cycloolefin resin films, cellulose acetate resin films such as triacetyl cellulose and diacetyl cellulose, polyester resin films such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polycarbonate resin films, and acrylic films. resin film, polypropylene resin film, and the like.

2. Laminate The laminate of the present invention comprises the pressure-sensitive adhesive sheet described above or a cured product thereof. When the pressure-sensitive adhesive sheet includes a release sheet, it exists in the laminate with the release sheet peeled off. That is, it can be said that the laminate includes the pressure-sensitive adhesive layer.

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

Furthermore, the laminate of the present invention can have adherends on both sides of the pressure-sensitive adhesive sheet. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, a laminate is formed by irradiating an active energy ray in a state where two adherends are laminated with a semi-cured pressure-sensitive adhesive sheet to post-cure the pressure-sensitive adhesive layer. is preferred. Here, the adherend is more preferably a base material or an optical member, and particularly preferably a polycarbonate base material, a polarizing plate, a transparent film, a transparent resin or glass.

FIG. 2 is a schematic diagram showing a cross section of an example of a laminate. FIG. 2 is a cross-sectional view showing an example of the structure of a laminate 20 in which the pressure-sensitive adhesive sheet 21 of the present invention is adhered to a substrate 22 and an optical member 24. As shown in FIG. As shown in FIG. 2, the pressure-sensitive adhesive sheet 21 of the present invention is preferably used for bonding to the substrate 22, and may be used for bonding the substrate 22 and another optical member 24. preferable. In addition, the adhesive sheet 21 of the present invention may be used for lamination with a polarizing plate.

Examples of the optical member contained in the laminate include a shatterproof film bonded to each constituent member of an optical product such as a touch panel or an image display device or a cover lens of the outermost layer. 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.

Materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetylcellulose, polyimide, and cellulose acylate.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it can be used for bonding two adherends. In this case, the pressure-sensitive adhesive sheet of the present invention can be used for lamination of transparent optical films inside a touch panel, lamination of a transparent optical film and glass, lamination of a transparent optical film and a liquid crystal panel of a touch panel, and cover glass. and a transparent optical film, a cover glass and a transparent optical film, etc., and is useful when one of the members is a polycarbonate substrate. As the transparent optical film, 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, a hard coat layer may be provided on the transparent optical film or the polycarbonate substrate.

FIG. 3 is a schematic diagram showing a cross section of another example of the laminate of the present invention. As shown in FIG. 3, the adherend may have steps (27a, 27b, 27c, 27d). In FIG. 3, the substrate has stepped portions (27a, 27b) and the optical member has stepped portions (27c, 27d). The thickness of the stepped portions (27a, 27b, 27c, 27d) is usually 5-60 μm. As described above, the pressure-sensitive adhesive sheet 21 of the present invention can be adhered to a member having a stepped portion, and can follow unevenness caused by the stepped portion.

The method for producing the laminate is not particularly limited. For example, after the adhesive layer of the adhesive sheet described above is laminated to the adherend in a semi-cured state, the adhesive layer is post-cured by irradiating an active energy ray. a step of allowing Specifically, the method for producing a laminate includes a step 1 of laminating an adherend on at least one side of an adhesive sheet, and irradiating the adhesive layer of the adhesive sheet with an active energy ray. has a step 2 of post-curing the . That is, the method for producing a laminate can include a step of forming an adhesive layer by the same method as the above-described method for forming an adhesive layer.

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.

(Synthesis example 1)
<Production of crosslinkable (meth)acrylic copolymer (a-1)>
Butyl acrylate monomer (BA), methyl acrylate monomer (MA) and methyl methacrylate (MMA) as monomer B (monomer having no functional group exhibiting cross-linking reactivity), and acrylic acid as monomer A (monomer having acid group) (AA) was prepared, and BA, MA, MMA and AA were blended in a mass ratio of 90:1:4:6 to prepare a monomer mixture. After mixing this monomer mixture and AIBN (azobisisobutyronitrile) as a radical polymerization initiator to obtain a mixture, the mixture is heated to 60° C. for random copolymerization to obtain a crosslinkable (meth)acrylic A copolymer (a-1) was obtained.

(Example 1)
<Preparation of adhesive composition (A-1)>
Per 100 parts by mass of the crosslinkable acrylic copolymer (a-1) produced in Synthesis Example 1, 0.05 parts by mass of an epoxy compound (Tetrad X, manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a cross-linking agent, containing a cyclic ether 10 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate (OXE-10, manufactured by Osaka Organic Chemical Industry Co., Ltd.) as a monomer, and bisphenol A ethylene oxide-modified diacrylate (Toagosei Co., Ltd.) as a polyfunctional monomer. 10 parts by mass of Aronix M211B, Tg = 75 ° C.), and 0.7 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (BASF Japan Co., Ltd., IRGACURE 184) as a photopolymerization initiator. , Ethyl acetate was added as a solvent so that the solid content concentration was 40% by mass to obtain a semi-cured pressure-sensitive adhesive composition (A-1).

<Preparation of adhesive layer (A-1)>
Next, as the first release sheet, a polyethylene terephthalate film having a thickness of 100 μm provided with an easy-adhesive layer treated with a silicone-based release agent (heavy separator film, Teijin DuPont Films Co., Ltd., release-treated polyethylene terephthalate film) was prepared. On the surface of the easy-adhesive layer side of the first release sheet, the pressure-sensitive adhesive composition (A-1) is applied so that the coating thickness after drying is 25 μm, "Doctor Blade YD type" manufactured by Yoshimitsu Seiki Co., Ltd. After uniformly coating at to prepare a coating film of the pressure-sensitive adhesive composition (A-1), it is dried for 3 minutes in an air circulation constant temperature oven at 100 ° C. to the surface of the first release sheet. An adhesive layer (A-1) was formed.

Next, a second release sheet having a thickness of 75 μm (a light separator film, manufactured by Teijin Dupont Films Co., Ltd., a release-treated polyethylene terephthalate film) to which a release treatment with higher release properties than the first release sheet was applied. prepared. This second release sheet was attached onto the adhesive layer (A-1) formed on the surface of the first release sheet. As a result, the first release sheet/adhesive layer (A-1)/second release sheet configuration in which the adhesive layer (A-1) is sandwiched between a pair of release sheets having different peeling strengths is released. A pressure-sensitive adhesive sheet with a sheet was obtained. This pressure-sensitive adhesive sheet with a release sheet was left to stand for 7 days under the conditions of 23° C. and 50% relative humidity for aging treatment.

(Example 2)
In the same manner as in Example 1 except that tetrahydrofurfuryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., Viscoat #150) was used instead of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer. A pressure-sensitive adhesive sheet with a release sheet was obtained.

(Example 3)
(2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate (MEDOL-10, manufactured by Osaka Organic Chemical Industry Co., Ltd.) instead of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that

(Example 4)
5 parts by mass of acrylate having a tetrahydrofurfuryl structure (Viscoat #150D, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 10 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer. A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except for the above.

(Example 5)
Example 1 except that an acrylate having a tetrahydrofurfuryl structure (manufactured by Osaka Organic Chemical Industry Co., Ltd., Viscoat #150D) was used instead of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer. A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner.

(Example 6)
20 parts by mass of acrylate having a tetrahydrofurfuryl structure (Viscoat #150D, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 10 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate as a cyclic ether-containing monomer. A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except for the above.

(Example 7)
Example 5 except that trimethylolpropane propylene oxide-modified triacrylate (manufactured by Toagosei Co., Ltd., Aronix M321, Tg = 50 ° C.) was used instead of bisphenol A ethylene oxide-modified diacrylate as a polyfunctional monomer. A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner.

(Comparative example 1)
A pressure-sensitive adhesive sheet with a release sheet was prepared in the same manner as in Example 1, except that no cyclic ether-containing monomer was used and that bisphenol A ethylene oxide-modified diacrylate was changed to 15 parts by mass as the polyfunctional monomer. Obtained.

(Comparative example 2)
Using 15 parts by mass of isobornyl acrylate (IBXA) instead of a cyclic ether-containing monomer, changing 15 parts by mass of bisphenol A ethylene oxide-modified diacrylate as a polyfunctional monomer, and epoxy-based as a cross-linking agent A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1, except that the compound (Tetrad X, manufactured by Mitsubishi Gas Chemical Company, Inc.) was changed to 0.5 parts by mass.

(Comparative Example 3)
A monofunctional monomer having a cyclic ether structure, a polyfunctional monomer and a photopolymerization initiator were not used, and an epoxy compound (Mitsubishi Gas Chemical Co., Ltd., Tetrad X) was used as a cross-linking agent at 0.5. A pressure-sensitive adhesive sheet with a release sheet was obtained in the same manner as in Example 1, except that the amount was changed to parts by mass.

<Gel fraction>
The pressure-sensitive adhesive layer was cut into a size of 100 mm×60 mm to prepare a semi-cured sample for measurement. On the other hand, the pressure-sensitive adhesive layer was cut to 100 mm × 60 mm, and irradiated with ultraviolet rays from the first release sheet side, which is a heavy separator film, so that the integrated light amount was 3000 mJ / cm ^2. For measurement after post-curing A sample was made.
About 0.1 g of each sample for measurement 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 150-mesh stainless steel wire mesh, and the residue on the wire mesh was dried at 100° C. for 1 hour to measure the dry mass (g). From the obtained dry mass, the following formula gel fraction (% by mass) = (dry mass / collected mass of adhesive sheet) × 100
The gel fraction was determined by

<Probe tack value>
The second release sheet, which is the light separator film of the adhesive sheet, was peeled off, and the exposed surface was attached to the PET film. Next, ultraviolet rays were irradiated from the side of the first release sheet, which is a heavy separator film, so that the integrated amount of light was 3000 mJ/cm ² to prepare a sample for measurement. A sample for measurement was cut into a size of 3 cm×3 cm and measured with a probe tack tester under the following conditions.
Measuring equipment: NS probe tack tester (manufactured by Nichiban Co., Ltd.)
Probe diameter: 5mmφ
Probe base material: Stainless steel surface finish AA#400 mirror finish Weight: 19.6 g (brass)
Probe moving speed: 1.0 cm/second Dwell time: 1 second In the probe tack test, the measurement temperature was 23°C and the relative humidity was 50%.

<Constant load peeling distance>
The light release separator, which is the second release sheet, was peeled off, and instead of the peeled separator, a triacetyl cellulose film (Fujitac TD60UL, thickness 60 μm, manufactured by Fuji Film Co., Ltd.) was laminated with a hand roller to prepare a laminated film. This laminated film was cut into a size of 25 mm in width and 100 mm in length, and the first release sheet was peeled off. Next, of the exposed 25 mm wide and 100 mm long adhesive surface, a region of 25 mm wide and 75 mm long was applied to the adherend (polycarbonate plate with hard coat layer: Iupilon MR58, thickness 1 mm, manufactured by Mitsubishi Gas Chemical Company, Inc.). A 2 kg pressing roller was applied to the side. In this state, the film was held in an autoclave at 40°C and 5 atm for 30 minutes to adhere to the PC plate, and then irradiated with ultraviolet rays from the triacetyl cellulose film side so that the integrated light amount was 3000 mJ/cm ² . A test piece was produced.
This test piece was then left for 24 hours in an environment of i) 85°C, 85% relative humidity, and ii) 85°C, 10% relative humidity, and then i) 85°C, 85% relative humidity, and ii) Under an environment of 85° C. and a relative humidity of less than 10%, as shown in FIG. A load of 100 g was applied in a direction of 90° to the plane of the adherend 32, and left in that state for an additional 5 minutes. The length L (constant load peeling distance) of the portion where the laminated film was peeled during that time was measured.
A: No peeling was observed, or peeling of less than 1 mm was observed.
○: Peeling of 1 mm or more and 50 mm or less was observed.
x: Peeling exceeding 50 mm was observed.

<Workability>
First, the second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and attached to a PET film having a thickness of 25 μm. Next, the first release sheet, which is a heavy separator film, was peeled off and attached to a PC board. A sample composed of PET/adhesive layer/PC was autoclaved (40° C., 0.5 MPa, 30 min), then irradiated with ultraviolet rays from the PET film side so that the integrated light amount was 3000 mJ/cm ² , and the test sample got Next, the edge of the test sample was cut using a guillotine cutter, and the cut edge was scraped off from the PC board side by hand so as to peel off the PET film. The peeling distance at that time was measured.
A: The peeling distance was less than 0.05 mm.
Good: The peeling distance was 0.05 mm or more and less than 0.1 mm.
x: The peeling distance was 0.1 mm or more.

<Durability>
The second release sheet, which is a light separator film of the pressure-sensitive adhesive layer, was peeled off and pasted to a triacetyl cellulose film (Fuji Tac TD60UL, thickness 60 µm, manufactured by Fuji Film Co., Ltd.). Next, the first release sheet, which is a heavy separator film, was peeled off and adhered to a PC plate (polycarbonate plate with a hard coat layer: Iupilon MR58, thickness 1 mm, manufactured by Mitsubishi Gas Chemical Company, Inc.). A sample composed of triacetyl cellulose film/adhesive layer/PC was autoclaved (40°C, 0.5 MPa, 30 min), and then irradiated with ultraviolet rays from the triacetyl cellulose film side so that the integrated amount of light was 3000 mJ/cm ² . Irradiated and test samples measuring 100 mm x 200 mm were obtained. After that, the test sample was allowed to stand under an environment of i) 85° C., 85% relative humidity, ii) 85° C., less than 10% relative humidity, and iii) ii) 105° C., less than 10% relative humidity, respectively for 240 hours. After that, the test sample was observed to see if there was any lifting or peeling. Note that the determination of the condition i) indicates the high temperature and high humidity durability, and the determination of the conditions ii) and iii) indicates the high temperature durability.
○: No lifting and peeling of 1.0 mm or more is observed ×: Lifting and / or peeling of 1.0 mm or more is observed

(Evaluation results)
Table 1 shows the evaluation results of gel fraction, probe tack value, workability evaluation, and constant load peel distance (85° C., relative humidity of 85% and 85° C., relative humidity of less than 10%). It was found that the pressure-sensitive adhesive sheets obtained in each example can exhibit excellent adhesion to substrates and durability even under high-temperature and high-humidity conditions. In addition, the pressure-sensitive adhesive sheets obtained in each example had no stickiness on the end surface and had good workability. On the other hand, the pressure-sensitive adhesive sheets obtained in Comparative Examples were inferior in substrate adhesion and durability and/or workability under high-temperature and high-humidity conditions.

Claims (7)

A pressure-sensitive adhesive sheet comprising a pressure-sensitive 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 a crosslinkable (meth)acrylic copolymer having an acid group is crosslinked with a crosslinking agent,
The polymerizable monomer includes a monofunctional monomer having a cyclic ether structure and a polyfunctional monomer having two or more polymerizable double bonds in the molecule ,
The monofunctional monomer having a cyclic ether structure is a (meth)acrylic ester having a 4-membered or higher cyclic ether structure,
The polyfunctional monomer has a bisphenol skeleton in the molecule,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer satisfies the following physical properties (1) and (2) when the pressure-sensitive adhesive layer is irradiated with an active energy ray so that the integrated light amount is 3000 mJ/cm ² and post-cured.
Physical properties (1): i) 85° C., 85% relative humidity, and ii) 85° C., less than 10% relative humidity, each constant load peel distance measured under the following (measurement conditions) is 50 mm or less:
Physical property (2): Probe tack value is 1.5 N/5 mmφ or less;
(Measurement condition)
A 25 mm wide and 75 mm long area of the adhesive surface of the adhesive layer having a size of 25 mm wide and 100 mm long is attached to an adherend and post-cured. i) 85° C., 85% relative humidity, and ii) 85° C., relative humidity of less than 10%. . A load of 100 g was applied to the end of the non-bonded area of the pressure-sensitive adhesive layer in the length direction for 5 minutes. and ii) measured as each constant load peel distance at 85°C and less than 10% relative humidity. 2. 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 50 parts by mass with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein said cyclic ether structure is a 4- to 6-membered ring. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the polyfunctional monomer is contained in an amount of 1 to 15 parts by mass with respect to 100 parts by mass of the crosslinkable (meth)acrylic copolymer. The adhesive layer has a gel fraction of 10 to 70%,
The adhesive layer after the post-curing has a gel fraction of 60 to 100%, and the gel fraction of the adhesive layer after the post-curing is higher than the gel fraction of the adhesive layer before the post-curing. 5. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein the pressure-sensitive adhesive sheet is 10% or more higher. A laminate comprising the adhesive sheet according to any one of claims 1 to 5 or a cured product thereof. A step of laminating an adherend on at least one side of the pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , and irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with an active energy ray to form the pressure-sensitive adhesive layer. A method for producing a laminate, which has a step of post-curing in order.

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