WO2020230875A1

WO2020230875A1 - Adhesive sheet and laminate

Info

Publication number: WO2020230875A1
Application number: PCT/JP2020/019371
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: 2019-05-16
Filing date: 2020-05-15
Publication date: 2020-11-19
Also published as: TW202108726A

Abstract

Provided is an adhesive sheet which has outstanding out-gassing resistance and which, when the adhesive sheet is adhered to a display or the like displaying a black screen, can improve unity with surroundings and enhance decorative properties when the lights are out, and which can deliver outstanding viewability and enhance contrast when text is displayed.　The present invention relates to an adhesive sheet provided with an adhesive agent layer, wherein: the adhesive agent layer contains a cross-linked (meth)acrylic copolymer, a polymerizable monomer having a polymerizable double bond inside the molecule, a photopolymerization initiator, and a coloring agent; the cross-linked (meth)acrylic copolymer has a structure in which the cross-linked (meth)acrylic copolymer is cross-linked by a cross-linking agent; and the polymerizable monomer includes at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure.

Description

Adhesive sheet and laminate

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

Adhesive sheets are used, for example, for bonding members together, and are widely used in various fields. In recent years, such adhesive sheets have also been used in display devices such as liquid crystal displays (LCDs) and input devices such as touch panels. By using an adhesive sheet for bonding each member such as an optical display constituting a display device or an input device, various devices can be easily manufactured with high accuracy.

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 bonded together by an adhesive sheet, and an adhesive sheet suitable for such applications is used. Have been proposed in various ways. For example, Patent Document 1 describes a (meth) acrylic acid ester polymer containing a (meth) acrylic acid alkyl ester, a reactive functional group-containing monomer having a reactive functional group in the molecule, and an N-vinylcarboxylic acid amide. A pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a cross-linking agent (B) has been proposed. It is said that blister resistance and moisture heat whitening resistance can be improved by using an acrylic polymer-based adhesive sheet 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 formed of a pressure-sensitive adhesive composition containing an acrylic polymer having a specific structure and having a pressure-sensitive adhesive layer having a predetermined shear storage elastic modulus.

On the other hand, in recent years, not only colorless and transparent adhesive sheets but also colored adhesive sheets are increasingly used as adhesive sheets used for bonding optical members used in display devices as described above from the viewpoint of design. It was. For example, Patent Document 3 describes a double-sided adhesive composed of a laminate including a flexible base material layer, a first black layer and a second black layer, and a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer. The sheet is disclosed. In such a case, the adhesive sheet used for laminating the black layer may be required to have a design property that does not impair the black appearance.

By the way, as a means for giving a black appearance to the adhesive sheet, a method of adding a pigment to the adhesive sheet is also known. For example, Patent Document 4 discloses a black foil-like pressure-sensitive adhesive containing a pressure-sensitive adhesive component, a black pigment, and a styrene-maleic acid resin.

Japanese Unexamined Patent Publication No. 2018-172537 Japanese Unexamined Patent Publication No. 2012-87240 Japanese Unexamined Patent Publication No. 2005-060435 Japanese Unexamined Patent Publication No. 2013-32430

However, when a member such as a resin cover panel is bonded with an adhesive sheet, there is a problem that air bubbles, floating, peeling, etc. may occur at the bonding interface due to gas (so-called outgas) generated from the member such as the cover panel. .. For example, outgas generation 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. That is, there is a problem that it is difficult to use a conventional adhesive sheet in that the outgas resistance is inferior to a member that easily generates outgas and is not protected by a hard coat layer or the like. It was. In the technique disclosed in Patent Document 1 and the like, a certain improvement in blister resistance (outgas resistance) can be expected, but for example, when polycarbonate having no hard coat layer is used, the blister resistance is sufficient. There was room for further improvement.

Further, as described above, a black adhesive sheet obtained by coloring a base material or an adhesive is known, but such an adhesive sheet is not supposed to be bonded to a transparent member or a display surface. Not only does it have no blister resistance as described above, but also the design and visibility when the display surface and the adhesive sheet are bonded have not been examined.

Therefore, in order to solve the problems of the prior art, the present inventors have a sense of unity with the surroundings when the adhesive sheet is attached to a display or the like having excellent outgas resistance and displaying a black screen. We proceeded with the study for the purpose of providing an adhesive sheet that can enhance the design and enhance the design, and can enhance the contrast and exhibit excellent visibility when characters are displayed.

As a result of diligent research to achieve the above object, the present inventors have added a colorant to a pressure-sensitive adhesive using a monofunctional monomer having a cyclic ether structure, and the total light transmittance of the pressure-sensitive adhesive sheet. By dividing the value by the haze value into the range of 0.5 to 120, even if it is used for bonding resin plates, blister due to outgassing does not occur, and an adhesive sheet is displayed on a display or the like displaying a black screen. It was found that an adhesive sheet capable of enhancing the design of the adhesive sheet and exhibiting excellent visibility when the characters are displayed can be obtained.

That is, the present invention includes, for example, the subjects described in the following sections.
[1]
An adhesive sheet with 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, a photopolymerization initiator, and a colorant.
The crosslinked (meth) acrylic copolymer has a structure in which the crosslinkable (meth) acrylic copolymer is crosslinked with a crosslinking agent.
The polymerizable monomer is a pressure-sensitive adhesive sheet containing at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure.
[2]
The adhesive sheet [3] of [1], wherein the value obtained by dividing the total light transmittance by the haze value is 0.5 to 120 or less.
The adhesive sheet according to any one of [1] and [2], which has a total light transmittance of 5 to 90%.
[4]
The adhesive sheet according to any one of [1] to [3], which has a haze of 0.1 to 15%.
[5]
The monofunctional monomer having a cyclic ether structure is contained in any one of [1] to [4], which is contained in an amount of 5 to 30 parts by mass with respect to 100 parts by mass of the crosslinkable (meth) acrylic copolymer. The described adhesive sheet.
[6]
The pressure-sensitive adhesive sheet according to any one of [1] to [5], wherein the cyclic ether structure is a 4- to 6-membered ring.
[7]
Any one of [1] to [4], wherein the monofunctional monomer having a chain 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. Adhesive sheet described in.
[8]
The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the colorant is at least one selected from metal oxide and carbon black.
[9]
The pressure-sensitive adhesive sheet according to any one of [1] to [8], wherein the colorant is a metal oxide.
[10]
The pressure-sensitive adhesive sheet [11] according to any one of claims [1] to [9], wherein the primary average particle size of the colorant is 0.01 μm or more and less than 5 μm.
The pressure-sensitive adhesive sheet according to any one of [1] to [10], wherein the polymerizable monomer contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule.
[12]
The pressure-sensitive adhesive sheet according to any one of [1] to [11], wherein the polyfunctional monomer has a bisphenol skeleton in the molecule.
[13]
The pressure-sensitive adhesive sheet according to any one of [1] to [12], 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.
[14]
The adhesive sheet according to any one of [1] to [13], 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.
[15]
The adhesive sheet according to [14], which is used for bonding the first member to one type of second member selected from the group consisting of a glass plate, a resin film, and a resin plate.
[16]
A laminate comprising the adhesive sheet according to any one of [1] to [15] or a cured product thereof.
[17]
The laminate according to [16], further comprising a resin molded body, which has a structure in which the resin molded body and a layer of the pressure-sensitive adhesive sheet or a cured product thereof are laminated.

The adhesive sheet according to the present invention has excellent outgas resistance, is less likely to cause air bubbles, floating and peeling after bonding, and further, when the adhesive sheet is bonded to a display or the like displaying a black screen, its design is improved. It is possible to obtain an adhesive sheet that can be enhanced and that can enhance the contrast and exhibit excellent visibility when characters are displayed.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, the expressions "contains" and "includes" include the concepts of "contains", "includes", "substantially consists" and "consists of only".

1. 1. Adhesive Sheet The adhesive sheet of the present invention includes 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, a photopolymerization initiator, and a colorant, and the crosslinked (meth) acrylic copolymer is contained. The acrylic copolymer 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 and a chain ether. It contains at least one of the monofunctional monomers having a structure.

In the present specification, "(meth) acrylic" means "acrylic" or "methacrylic", and "(meth) acrylate" means "acrylate" or "methacrylate".

Since the adhesive sheet of the present invention has the above-mentioned structure, it has blister resistance and can enhance its design when it is attached to a display or the like displaying a black screen. Specifically, when the adhesive sheet of the present invention is used for bonding a resin plate such as polycarbonate without causing air bubbles, floating or peeling due to outgas, and is bonded to a display displaying a black screen. Since the degree of black color development of the display (preferability of the degree of blackness) can be increased, the design of the display and the display device having the display can be enhanced. Further, even if the display is in a state where the black screen is not displayed, the degree of blackness of the display is increased by attaching the adhesive sheet, so that the sense of unity with the surroundings is emphasized and the design is enhanced.
Further, the adhesive sheet of the present invention has high visibility, and even when the adhesive sheet is attached to the visible surface side of the display, for example, the characters displayed on the display are prevented from being blurred or blurred. As described above, the adhesive sheet of the present invention has succeeded in having blister resistance even in the application of laminating resin plates, increasing the degree of black color development of displays and the like, and not deteriorating the visibility of displays and the like. It was done.

<Cross-linked (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, a known crosslinked (meth) acrylic copolymer used in an adhesive sheet can be widely applied.

(Crosslinkable (meth) acrylic copolymer)
The crosslinkable (meth) acrylic copolymer can have a structure in which a functional group exhibiting crosslinkability is bonded to the (meth) acrylic copolymer skeleton. The functional group exhibiting cross-linking 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 the pressure-sensitive adhesive layer is preferably 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 cross-linking reactivity does not contain a carboxy group. A functional group exhibiting a particularly preferable cross-linking reactivity is a hydroxyl group, and in this case, a cross-linked (meth) acrylic copolymer is also likely to be formed.

The crosslinkable (meth) acrylic copolymer may have, for example, a monomer unit having a functional group exhibiting crosslinkability and a monomer unit having no functional group exhibiting crosslinkability. .. In this case, the crosslinkable (meth) acrylic copolymer can be obtained, for example, by copolymerizing a monomer having a functional group exhibiting crosslinkability and a monomer having no functional group exhibiting crosslinkability. it can. Hereinafter, the monomer having a functional group exhibiting cross-linking reactivity is referred to as "monomer A", and the monomer having no functional group exhibiting cross-linking reactivity is 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-hydroxy3-phenoxypropyl (meth) acrylate, 2,2-dimethyl2-hydroxyethyl (meth) acrylate, 3-chloro2-hydroxypropyl (meth) acrylate, 2-hydroxy3- Hydroxyalkyl (meth) acrylates such as phenoxypropyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate; hydroxyalkyl (meth) acrylamide such as N-hydroxypropyl (meth) acrylamide; and the like can be mentioned.

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 preferable. In this case, it is easy to obtain an adhesive sheet having excellent outgas resistance. The hydroxyl group-containing (meth) acrylic monomer can 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, examples of the carboxy group-containing (meth) acrylic monomer include (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, citraconic acid, 2- (meth) acryloyloxyethyl phthalic acid, and 2-(. Examples thereof include meta) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxylethyl (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 also be a (meth) acrylic monomer having at least one functional group such as an amino group, an amide group, an epoxy group, a thiol group and an isocyanate group.

Examples of the monomer B include a (meth) acrylate having a linear, branched, or cyclic alkyl group, or a (meth) acrylate 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, and 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). It is preferably an alkyl (meth) acrylate such as an acrylate. In this case, it is easy to obtain an adhesive sheet having excellent outgas resistance. Monomer B can be used alone or in admixture of two or more different types.

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

In the polymerization for obtaining a crosslinkable (meth) acrylic copolymer, the ratio of the monomer A and the monomer B used is not particularly limited, and may be appropriately set according to the target crosslinkable (meth) acrylic copolymer. it can. For example, 0.5 to 60 parts by mass of monomer A (monomer having a crosslinkable functional group) can be contained per 100 parts by mass of the total amount of monomer A and monomer B. In this case, the adhesive sheet can have a desired adhesive force, and the outgas resistance is less likely to decrease. It is preferable that 1 to 55 parts by mass of monomer A is contained per 100 parts by mass of the total amount of monomer A and monomer B.

In the polymerization for obtaining a crosslinkable (meth) acrylic copolymer, a polymerizable monomer other than the monomer A and the monomer B can be used in combination, if necessary. Examples of such a polymerizable monomer include a radically polymerizable monomer copolymerizable with the monomer A and the monomer B other than the (meth) acrylate compound. 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 per 100 parts by mass of the total amount of the monomer A and the monomer B, for example.

In the production of the crosslinkable (meth) acrylic copolymer, the usage ratio (mass ratio) of the monomer A and the monomer B is contained 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 crosslink reactivity and the monomer unit having no functional group exhibiting crosslink reactivity.

In the polymerization method for obtaining a crosslinkable (meth) acrylic copolymer, a solvent can be used if necessary. The type of solvent is not particularly limited, and for example, known organic solvents used in polymerization can be widely used. For example, 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; can be mentioned. 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 if necessary, and for example, a 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), and the like. Examples thereof include di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, ammonium persulfate, photoinitiator (Irgacure or Omnirad (registered trademark) series, etc.).

The concentration of the polymerization initiator is not particularly limited, and for example, it can be appropriately adjusted within a range in which the obtained crosslinkable (meth) acrylic copolymer polymer 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 monomer A and the monomer B.

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

The polymerization time and polymerization temperature for obtaining a crosslinkable (meth) acrylic copolymer are not limited, and may be appropriately set according to the types of monomer A and monomer B used, the amount 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. For example, from the viewpoint that the adhesive strength of the adhesive sheet is unlikely to decrease, it can be 100,000 to 2,000,000, and 400,000 to 100. It is more preferable to make it 10,000.

The weight average molecular weight referred to in the present invention is a polystyrene-equivalent weight average molecular weight measured by a gel permeation chromatography (GPC) method. The GPC apparatus used in the GPC method is not particularly limited, and a commercially available GPC measuring machine, for example, LC-2000Plus series manufactured by JASCO Corporation, RI-2031Plus, UV-2075Plus or the like can be used as the detector. In this case, for example, a GPC column made by connecting four lines 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 is measured 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 crosslinkability and a monomer unit having no functional group exhibiting crosslinkability are randomly arranged. It can be a polymer. Alternatively, the crosslinkable (meth) acrylic copolymer may have other structures such as a block polymer.

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

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

The type of isocyanate cross-linking agent is not particularly limited, and known compounds can be widely used. Examples of the isocyanate cross-linking agent include polyisocyanates such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and xylylene diisocyanate; cyclopentylene diisocyanate and cyclohexylene diisocyanate. Such as alicyclic isocyanates, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and aromatic isocyanates such as 4,4'-diphenylmethane diisocyanate; are exemplified. The isocyanate cross-linking agent can 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 cross-linking agent.

Examples of the epoxy cross-linking 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, and 1,6-hexanediol. Diglycidyl ether, N, N, N', N'-tetraglycidyl-m-xylene diamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexanone, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl Examples thereof include ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether.

When the crosslinkable (meth) acrylic copolymer is crosslinked with a crosslinking agent to obtain a crosslinked (meth) acrylic copolymer, the ratio of the crosslinkable (meth) acrylic copolymer to 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 cross-linking (meth) acrylic copolymer. In this case, the adhesive sheet can have the desired adhesive strength. 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-linking (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 used in combination, the adhesive strength of the adhesive sheet tends 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 thereof include propyltriacoxysilane γ-methacryloxypropyltrialkoxysilane, γ-chloropropyltrialkoxysilane, γ-methacryloxypropyldialkoxysilane, γ-mercaptopropyltrialkoxysilane, and vinyltrialkoxysilane.

When a silane coupling agent is used in combination with a crosslinkable (meth) acrylic copolymer to be crosslinked with a crosslinkable agent, the amount used is 0.1 to 100 parts by mass of the crosslinkable (meth) acrylic copolymer. It can contain 5 parts by mass.

<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 contains 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 contains either a monofunctional monomer having a cyclic ether structure or a monofunctional monomer having a chain ether structure. It may include both.

(Monomer containing cyclic ether)
A 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 is referred to as “polymerizable monomer M”. Further, a monomer having both a polymerizable double bond and a cyclic ether structure in the molecule is referred to as a “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 from the viewpoint that the outgas resistance is easily improved, the cyclic ether structure is more preferably a 4-membered ring or more. That is, the cyclic ether structure is preferably a ring other than the 3-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, and for example, the number of oxygen atoms can be 1 or 2. Among the atoms constituting the ring of the cyclic ether structure, the atoms other than the oxygen atom are usually carbon atoms.

The cyclic ether structure is preferably a tetrahydrofuran structure. In this case, the adhesive sheet has particularly improved outgas resistance.

In the cyclic ether structure, an atom (for example, a carbon atom) other than the oxygen atom 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, and an alkynyl group having 2 to 10 carbon atoms, and more specifically. It is a methyl group, an ethyl group, an n-propyl group, an i-propyl group and the like.

When the cyclic ether structure has the above-mentioned substituents, the number of substituents, the bonding position and the like are not particularly limited, and the effect of the present invention is 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 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 an oxygen atom of an ester of a (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 to the oxygen atom of the ester. It intervenes with the ether structure.
-(CH ₂ ) _m- (1)
(In equation (1), m indicates an integer from 1 to 5)

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

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

The cyclic ether-containing monomer contained in the polymerizable monomer M may be used 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 more excellent outgas resistance of the pressure-sensitive adhesive sheet, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer (monofunctional monomer having a cyclic ether structure) is based on 100 parts by mass of the crosslinkable (meth) acrylic copolymer. It is preferably contained in an amount of 5 to 50 parts by mass.

More specifically, in the pressure-sensitive adhesive sheet, the cyclic ether-containing monomer is more 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. Especially preferable. 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, based on 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 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, a known monofunctional polymerizable monomer 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, the content thereof 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% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less.

(Chain ether-containing monomer)
A 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 type of the chain ether-containing monomer contained in the polymerizable monomer M is not particularly limited as long as it is a radically polymerizable monomer having a chain ether structure in the molecule, and known chain ether-containing monomers can 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.

The chain ether structure of the chain ether-containing monomer is not particularly limited. For example, as the chain ether structure, a structure having a structural unit represented by the following general formula (5) can be mentioned.

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

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

In the above formula (5), when R ¹ is an alkyl group, the type thereof is not particularly limited. The alkyl group may have a linear, branched or cyclic structure. For example, when the alkyl group is linear or branched, an alkyl group having 1 to 10 carbon atoms can be mentioned as such an alkyl group, and an alkyl group having 1 to 5 carbon atoms is preferable. , It is more preferable that it is an alkyl group having 1 to 4 carbon atoms. When R ¹ is an alkyl group, a particularly preferable alkyl group is a methyl group or an ethyl group from the viewpoint that the outgas resistance of the pressure-sensitive adhesive sheet is particularly likely to be improved.

When the alkyl group is cyclic, the number of carbon atoms of the alkyl group can be 3 or more, more preferably 4 or more, and particularly preferably 5 or more. When the alkyl group is cyclic, the number of carbon atoms of the alkyl group can be 20 or less, 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. A 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, the bonding position and the like 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, it is particularly preferably a phenyl group.

Examples of the chain ether-containing monomer include (meth) acrylic esters having a chain ether structure. In this case, for example, it has a structure in which a chain ether structure is directly or indirectly bonded to an oxygen atom of an ester of a (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 above general formula (1) or general formula (2) is the oxygen atom of the ester. It intervenes between the chain ether structure.

In the chain ether-containing monomer, a in the formula (1) is preferably 1 to 2. In the chain ether-containing monomer, n in the formula (2) is preferably 0 to 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 used alone or may contain two or more different chain ether-containing monomers.

The content of the chain ether-containing monomer in the adhesive sheet is not particularly limited. From the viewpoint of better outgas resistance of the pressure-sensitive adhesive sheet, 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. It is preferably contained in an amount of 5 to 50 parts by mass.

More specifically, in the pressure-sensitive adhesive sheet, the chain ether-containing monomer is more preferably contained in an amount of 7 parts by mass or more with respect to 100 parts by mass of the crosslinkable (meth) acrylic copolymer, and is contained in an amount of 10 parts by mass or more. 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, more preferably 30 parts by mass or less, based on 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, a known monofunctional polymerizable monomer 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, preferably 10% by mass or less, based on the total mass of the polymerizable monomer M. 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 preferably contains a polyfunctional monomer having two or more polymerizable double bonds in the molecule. In this case, the adhesive sheet can easily improve the outgas resistance, and can also suppress shrinkage when the 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 the polyfunctional monomer is not particularly limited, and for example, a known polyfunctional monomer used in an adhesive sheet can be widely used. Above all, the polyfunctional monomer preferably has a bisphenol skeleton in the molecule from the viewpoint that shrinkage when the pressure-sensitive adhesive sheet is cured can be more easily suppressed. 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, 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, and 1, (meth) acrylate. 4-butylene glycol, di (meth) acrylic acid 1,9-nonanediol, diacrylic acid 1,6-hexanediol, di (meth) acrylic acid polybutylene glycol, di (meth) acrylic acid neopentyl glycol, di (meth) ) Tetraethylene glycol acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, diacrylate of bisphenol A diglycidyl ether, trimethylol propane tri (meth) acrylate, tri (meth) acrylic Examples thereof include (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 diacrylate of bisphenol A diglycidyl ether, diacrylate of propoxylated bisphenol A, and diacrylate of bisphenol F diglycidyl ether.

Commercially available products can also be used as the polyfunctional monomer. For example, a trifunctional monomer M310 (trimethylolpropane PO-modified triacrylate) or a trifunctional monomer M321 (trimethylolpropanpropylene oxide-modified triacrylate) manufactured by Toa Synthetic Co., Ltd., Bifunctional monomer M211B (bisphenol A EO modified diacrylate) manufactured by Toa Synthetic Co., Ltd., bifunctional monomer "Aronix M208" (bisphenol F EO modified diacrylate) manufactured by Toa Synthetic Co., Ltd., bifunctional monomer "bisphenol F EO modified diacrylate" manufactured by Osaka Organic Chemical Industry Co., Ltd. Examples thereof include "Viscoat # 700HV" (bisphenol A EO (3.8) adduct diacrylate).

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 a 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 of the outgas resistance of the pressure-sensitive adhesive sheet and the suppression of shrinkage after curing, the polyfunctional monomer in the pressure-sensitive adhesive sheet is 1 to 15 with respect to 100 parts by mass of the crosslinkable (meth) acrylic copolymer. It is preferably contained in parts 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, based on 100 parts by mass of the crosslinkable (meth) acrylic copolymer. Further, in the pressure-sensitive adhesive sheet, the polyfunctional monomer is preferably 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 of only a monofunctional monomer and a polyfunctional monomer. Furthermore, the polymerizable monomer M can be composed of only a cyclic ether-containing monomer and a polyfunctional monomer, or the polymerizable monomer M is a chain ether-containing monomer and a polyfunctional monomer. It can also be composed of only.

(Photopolymerization initiator)
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 the polymerizable monomer M can be photopolymerized, and for example, a known photopolymerization initiator can be widely used.

The photopolymerization initiator is not particularly limited, and is, for example, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-henylpropanol, 1- [4-( 2-Hydroxyethoxyl) -phenyl] -2-hydroxy-methylpropanol, 2-hydroxy-1- (4- (4- (2-hydroxy-2-methylpropionyl) benzyl) phenyl) -2-methyl-1- Alkylphenone-based photopolymerization initiators such as propanone, acylphosphine oxide-based polymerization initiators such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl) phenylphosphine oxide, Examples thereof include an intramolecular hydrogen abstraction type photopolymerization initiator such as methyl benzoylite and 4-methylbenzophenone, an oxime ester-based photopolymerization initiator, and a cationic photopolymerization initiator. Only one type of photopolymerization initiator may be used, or two or more types may be used in combination.

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. With respect to the content of the photopolymerization initiator, based on the crosslinkable (meth) acrylic copolymer, the content of the photopolymerization initiator per 100 parts by mass of the crosslinkable (meth) acrylic copolymer is 0. It can be 05 to 5 parts by mass.

(Colorant)
The pressure-sensitive adhesive sheet of the present invention contains a colorant. Examples of the colorant include a dye colorant and a pigment colorant. Among them, the colorant is preferably a pigment colorant, and more preferably at least one selected from a metal oxide and carbon black. Further, the colorant is preferably a black pigment, and particularly preferably a metal oxide. By using a metal oxide as the colorant, the visibility of the pressure-sensitive adhesive sheet can be enhanced more effectively. In addition to the metal oxide and carbon black, the colorant may contain other colorants. Examples of other colorants include aniline black and activated carbon.

Metal oxides include copper oxide, iron tetraoxide, manganese dioxide, titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, iron titanate, copper-chromium oxide, copper-manganese oxide, Examples thereof include copper-iron-manganese oxide, copper-chromium-manganese oxide, copper-iron-chromine oxide, titanium black and the like. Above all, the metal oxide is more preferably a metal oxide whose metal type is selected from copper, iron and manganese. By selecting the above type as the colorant, the color stability becomes good.

The colorant is fine particles, and the primary average particle size of the colorant is preferably 0.01 μm or more. Further, the primary average particle size of the colorant is preferably less than 5 μm, more preferably less than 3 μm, further preferably less than 1 μm, and particularly preferably less than 0.5 μm. By setting the primary average particle size of the colorant within the above range, the visibility of the pressure-sensitive adhesive sheet can be improved more effectively.

The content of the colorant is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and 0.2 part by mass or more with respect to 100 parts by mass of the acrylic polymer. Is even more preferable. The content of the colorant is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, based on 100 parts by mass of the acrylic polymer.

It is preferable that the colorant is mixed with the acrylic polymer in a state of being dispersed in the dispersed resin. Examples of the dispersion resin include polyester resin, urethane resin, acrylic resin, and polyether resin.

<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 a photopolymerization initiator. As long as the effect of the present invention is not impaired, the pressure-sensitive adhesive layer may contain other components such as an antistatic agent, an antioxidant, and a preservative. 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 pressure-sensitive adhesive layer. It can be 0.1% by mass or less.

(Method of forming the adhesive layer)
The method for forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a known method 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 is 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. , A step of forming an adhesive layer can be provided.

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 blending ratio. It can be prepared by 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 each of the crosslinkable (meth) acrylic copolymer, the crosslinker, 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 are within the above-mentioned ranges, respectively. The content of each component contained in the above can be adjusted.

The pressure-sensitive adhesive composition may contain, for example, a solvent in order to improve the coatability. The solvent is not particularly limited, and for example, an ester compound such as methyl acetate and ethyl acetate; an ether compound such as diethyl ether; a ketone compound such as acetone and methyl ethyl ketone; an aliphatic hydrocarbon such as hexane and heptane; and an alicyclic such as cyclohexane. Formula hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene; chlorine-based 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.

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 in consideration of coatability, and 15 to 50. It is more preferable to use a solvent so as to be in the range of mass%.

The method of applying the pressure-sensitive adhesive composition onto the base material is not particularly limited, and for example, a known coating method can be widely adopted. For example, the pressure-sensitive 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 amount of the pressure-sensitive adhesive composition applied 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 later is 5 to 1000 μm.

The type of base material for applying the pressure-sensitive adhesive composition is not particularly limited, and the base material 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.

Examples of the release sheet include a so-called separator used to protect the adhesive layer in the adhesive sheet. More specifically, examples of the release sheet include a resin film provided with a release layer.

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

The release layer is a layer formed on at least one side 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, a known component used as a release layer in an adhesive sheet can be widely applied. For example, a release layer can be formed from a known silicone material.

When the release sheet is used as a 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 a base material such as the release sheet to form a coating film, and then a drying treatment 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 conventional method for drying a coating film of an adhesive composition can be widely adopted. Such a drying treatment can be performed using, for example, a known heating device or the like. The heating temperature can be, for example, 50 to 200 ° C, 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 is, for example, 1000 ppm or less, and in 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 appropriately within a time of about 1 to 30 minutes.

By the 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 cross-linking reaction of the cross-linking (meth) acrylic copolymer mainly proceeds and the curing proceeds, but the polymerizable monomer M is in a state in which polymerization has not yet occurred. 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-linking (meth) acrylic copolymer is not always completed by the drying treatment, and the cross-linking reaction can also proceed by the aging treatment described later.

A protective layer for protecting the adhesive layer can be further attached to the adhesive layer formed in this way. In this case, the protective layer is attached to the surface of the pressure-sensitive adhesive layer opposite to the base material. Examples of the protective layer include a release sheet as described above. As the release sheet as the protective layer, a resin film or the like having a release layer can be mentioned as in the case of the base material. Examples of the resin film include polyethylene terephthalate film and the like as described 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 each surface 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). It is preferable that the peeling force of the release layer of the sheet) is different from the adhesive force of the release layer of the release sheet (second release sheet) for forming the protective layer. That is, when both the base material and the protective layer are release sheets, it is preferable that the release force of each release sheet is different. In this case, when the release sheet is peeled off, it becomes easy to selectively peel off only one of the release sheets, and it is easy to suppress the so-called crying phenomenon.

A desired adhesive sheet can be obtained by forming an adhesive layer, 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-linking (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 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 according to the intended use and the like. For example, when the adhesive sheet is used for bonding members such as a resin cover panel in an input device or the like, the thickness of the adhesive layer can be 5 to 1000 μm. The adhesive sheet may be either a single-sided adhesive sheet or a double-sided adhesive sheet, and is usually a double-sided adhesive sheet.

The pressure-sensitive adhesive sheet may be formed of only the pressure-sensitive adhesive layer, or may have another layer if necessary. The other layer can be formed on one or both sides of the pressure-sensitive adhesive layer. As another layer, the above-mentioned release sheet can be mentioned. When the release sheets are formed on both sides of the pressure-sensitive adhesive layer, the release forces of both release sheets (the first release sheet and the second release sheet) can be made different as described above. When the peeling forces of the two release sheets are different, for example, when the release sheets are peeled off, it becomes easy to selectively peel off only one of the release sheets, and it is easy to suppress the so-called crying phenomenon.

For example, in the above-mentioned method for forming an adhesive layer, when a release sheet is used as a base material and a release sheet is also used as a protective layer, an adhesive sheet having release sheets on both sides of the adhesive layer (release layer). Adhesive sheet with attachment) can be obtained directly. After forming the pressure-sensitive adhesive layer, release sheets may be separately provided on both sides thereof to obtain a pressure-sensitive adhesive sheet with a release layer.

When the adhesive sheet has a release sheet, these release sheets can have a function as a so-called separator in the 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 pressure-sensitive adhesive layer may have different thicknesses from each other.

<Optical characteristics of adhesive sheet>
The total light transmittance of the pressure-sensitive adhesive sheet of the present invention is preferably 5% or more, more preferably 10% or more, further preferably 20% or more, still more preferably 30% or more. , 40% or more is particularly preferable. The total light transmittance of the pressure-sensitive adhesive sheet is preferably 90% or less, more preferably 86% or less, more preferably 80% or less, still more preferably 75% or less. It is particularly preferably 70% or less. By setting the total light transmittance of the adhesive sheet within the above range, it is possible to more effectively increase the degree of black color development of the display or the like.

The haze of the adhesive sheet is preferably 0.1% or more. The haze of the pressure-sensitive adhesive sheet is preferably 15% or less, more preferably 10% or less, further preferably 8% or less, and particularly preferably 6% or less. By setting the haze of the adhesive sheet within the above range, visibility can be maintained while increasing the degree of black color development of the display or the like.

In the pressure-sensitive adhesive sheet of the present invention, the value obtained by dividing the total light transmittance of the pressure-sensitive adhesive sheet by the haze value may be 0.5 to 120, more preferably 0.8 to 100. By setting the value obtained by dividing the total light transmittance by the haze value within the above range and setting the total light transmittance and the haze of the adhesive sheet within a predetermined range, the degree of black color development of the display or the like can be more effectively increased. The visibility of the display or the like can be improved more effectively.

<How to use the adhesive sheet>
The adhesive sheet can be widely used in applications where members (adhesive bodies) such as substrates and films are bonded and bonded to each other.

For example, by interposing an adhesive sheet between a pair of adherends and laminating the adherends with the adhesive sheet to form a laminate, the adherends can be bonded to each other with the adhesive sheet. In particular, the durability can be maximized by irradiating the laminated body after bonding the adherends with the adhesive sheet with active energy rays. When the adhesive sheet includes a release sheet, the adhesive sheet is interposed between the pair of adherends with the release sheet peeled off.

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, the pressure-sensitive adhesive layer exists when the pressure-sensitive adhesive layer is irradiated with active energy rays. The polymerization reaction of the monomer M is caused by the photopolymerization initiator. As a result, the curing of the pressure-sensitive adhesive layer further progresses, and the curing of the pressure-sensitive adhesive layer further adheres the adherends to each other more firmly.

By curing the pressure-sensitive adhesive layer, 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 cyclic ether-containing monomer and / or a structural unit derived from 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 not easily affected by the outgas. , Bubbles, floating and peeling are less likely to occur even after the adhesive layer has hardened.

Here, examples of the active energy ray include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable. As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high pressure mercury lamp, a metal halide lamp, a carbon arc, a xenon arc, an electrodeless ultraviolet lamp and the like can be used. As the electron beam, for example, an electron beam emitted from various electron beam accelerators such as Cockloftwald type, Bandecliff type, resonance transformer type, insulated core transformer type, linear type, dynamistron 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 laminated body can be irradiated with the active energy ray. From this point of view, it is preferable that at least one of the adherends is transparent. For irradiation of the active energy ray, for example, a known active energy ray irradiation device can be used.

Since the adhesive sheet has excellent outgas resistance, it can be particularly preferably used for applications in which bubbles and the like are likely to be generated due to outgas from the adherend.

The adhesive sheet can be used for bonding with one type 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 production method, or can be obtained from a commercially available product. When the first member is a resin plate, for example, it can be obtained by a casting method or by various molding methods such as an injection molding method. The first member may be molded into various shapes other than the plate, sheet and 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, the thickness thereof 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 an acrylic resin such as polymethylmethacrylate, a polycarbonate resin, and a styrene resin such as polystyrene. The resin may contain two or more different types, and examples thereof include a composite material containing an acrylic resin and a polycarbonate resin. Among them, the pressure-sensitive adhesive sheet is preferably used for bonding a polymethyl methacrylate resin plate, a polycarbonate resin plate, and the like, and particularly preferably used for bonding a polycarbonate resin plate. That is, when bonding is performed using an adhesive sheet, one of the adherends can be a resin plate such as a polycarbonate resin.

Polycarbonate resin is known as a material that easily generates outgas compared to acrylic resin and the like. For this reason, in order to suppress the problem of outgas, conventionally, a device such as providing a hard coat layer on the polycarbonate resin plate has been made, but when the adhesive sheet of the present invention is used, the hard coat layer is not provided. Even if it is a polycarbonate resin plate, the influence of outgas can be suppressed. Outgas may be generated, for example, when irradiated with active energy rays at the time of bonding, or may be gradually generated with time after bonding.

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

Since the adhesive sheet has excellent outgas resistance and is particularly suitable for bonding with a polycarbonate resin plate as an adherend, it is used for display devices such as liquid crystal displays (LCDs) and input devices such as touch panels. It can be used particularly preferably. Examples of the 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, and a transparent conductive film in which a transparent resin film is coated with a conductive polymer. , Hard coat film, fingerprint resistant film and the like. Examples of the constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness improving film used in a liquid crystal display device.

2. Laminated body The laminated body of the present invention includes 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 laminated body includes the pressure-sensitive adhesive layer.

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

The laminated body may be further provided with another layer other than the pressure-sensitive adhesive layer, and examples thereof include the first member. When the laminated body includes the first member, the laminated body has, for example, a structure in which the first member and a layer of the adhesive sheet or a 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>. The first member is preferably a molded body of various resins such as a polycarbonate resin plate.

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

Examples of the base material layer include ITO substrate, glass substrate, metal substrate, resin substrate, paper, cloth, non-woven fabric and the like.

When the laminate includes a cured product of the adhesive sheet, for example, a laminate having an adhesive sheet before curing (that is, an adhesive layer in a semi-cured state) is produced, and the laminate is irradiated with active energy rays. By doing so, it is possible to obtain a laminate having a cured product of the adhesive sheet.

Since the laminate is excellent in outgas resistance, it can be particularly suitably used for applications such as display devices such as liquid crystal displays (LCDs) and input devices such as touch panels.

The method for producing the laminate is not particularly limited. For example, after the pressure-sensitive adhesive layer of the above-mentioned pressure-sensitive adhesive sheet is attached to the adherend in a semi-cured state, the pressure-sensitive adhesive layer is post-cured by irradiating with active energy rays. It can include a step of causing. Specifically, the method for producing the laminated body includes the step 1 of laminating the 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. 2 is sequentially provided by step 2 of post-curing. That is, the method for producing the laminated body can include a step of forming the pressure-sensitive adhesive layer by the same method as the above-mentioned method for forming the pressure-sensitive adhesive layer.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the aspects of these Examples.

(Synthesis Example 1)
<Preparation of crosslinkable (meth) acrylic copolymer (a-1)>
Butyl acrylate (BA) is prepared as monomer B (monomer having no functional group exhibiting cross-linking reactivity), and 2-hydroxyethyl acrylate (2HEA) is prepared as monomer A (monomer having functional group exhibiting cross-linking reactivity). , BA was 75% by weight and 2HEA was 25% by weight to prepare a monomer mixture. This monomer mixture is mixed with an ethyl acetate solution of 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator to obtain a mixture, and then the mixture is heated to 60 ° C. at random. It was copolymerized to obtain a crosslinkable (meth) acrylic copolymer (a-1). 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 products were connected and used)
Column temperature: 40 ° C
Sample concentration: 0.5% by mass
Detector: RI-2031plus (manufactured by JASCO)
Pump: RI-2080plus (manufactured by JASCO)
Flow rate (flow velocity): 0.8 ml / min Injection amount: 10 μL
Calibration curve: Standard polystyrene Shodex standard polystyrene (manufactured by Showa Denko KK) A calibration curve of 10 samples from Mw = 1320 to 2.5 million 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-acryloyl morpholine, 15% by mass of isobornyl acrylate, 5% by mass of N-vinylacetamide and 2-hydroxyethyl acrylate 15 The parts by mass were 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 a weight average molecular weight (Mw) of 510,000.

(Synthesis Example 2-2)
A crosslinkable acrylic copolymer was prepared as follows according to the method described in Example 1 of Patent Document 2 described above. 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), radical polymerization initiation As an agent, 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved in ethyl acetate. The solution was heated to 65 ° C. and randomly copolymerized 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)>
0.2 parts by mass of a tolylene diisocyanate compound (Coronate L-55E, manufactured by Toso Co., Ltd.) as a cross-linking agent with respect to 100 parts by mass of the crosslinkable acrylic copolymer (a-1) produced in Synthesis Example 1, a silane cup. 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd., KBM-403) as a ring agent, and 3-ethyl-3-oxetanyl methyl acrylate (Osaka Organic Chemical Industry Co., Ltd.) as a cyclic ether-containing monomer OXE-10) 25 parts by mass, bisphenol A ethylene oxide-modified diacrylate (Aronix M211B, manufactured by Toa Synthetic Co., Ltd.) as a polyfunctional monomer, 12 parts by mass, and bis (2,4,6) as a photopolymerization initiator. -Trimethylbenzoyl) phenylphosphine oxide (BASF Japan, IRGACURE819) by 1.0 part by mass, and copper-iron-manganese oxide pigment (Dainichi Seika Kogyo), TM Black 3550 as a colorant ) Was added in an amount of 0.15 part, and ethyl acetate was added as a solvent so that the solid content concentration became 35% 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 100 μm-thick polyethylene terephthalate film having an easy-adhesive layer treated with a silicone-based release agent (heavy separator film, manufactured by Teijin DuPont Film Co., Ltd., release-treated polyethylene terephthalate film). ) Was prepared. The pressure-sensitive adhesive composition (A-1) is uniformly applied to the surface of the first release sheet on the side of the easy-adhesive layer so that the coating thickness after drying is 100 μm, and the pressure-sensitive adhesive is applied. After preparing the coating film of the composition (A-1), the pressure-sensitive adhesive layer (A-1) is formed on the surface of the first release sheet by drying in an air circulation type constant temperature oven at 90 ° C. for 3 minutes. did.

Next, a second release sheet having a thickness of 75 μm (light separator film, manufactured by Teijin DuPont Film Co., Ltd., release-treated polyethylene terephthalate film) having been subjected to a release treatment having a higher release property than the first release sheet was prepared. did. The second release sheet was laminated on the pressure-sensitive adhesive layer (A-1) formed on the surface of the first release sheet. As a result, the adhesive layer (A-1) is sandwiched between a pair of release sheets having different release strengths, and the composition of the first release sheet / adhesive layer (A-1) / second release sheet is peeled off. An adhesive sheet with a sheet was obtained. The 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)
The same method as in Example 1 except that 3-ethyl-3-oxetanylmethylmethacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., OXE-30) was used instead of 3-ethyl-3-oxetanylmethylacrylate as the cyclic ether-containing monomer. Obtained an adhesive sheet with a release sheet.

(Example 3)
As the cyclic ether-containing monomer, 20 parts by mass of tetrahydrofurfuryl acrylate (Viscoat # 150 manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 25 parts by mass of 3-ethyl-3-oxetanylmethyl acrylate, and bisphenol as a polyfunctional monomer. A 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 Toa Synthetic 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 (manufactured by Osaka Organic Chemical Industry Co., Ltd., Viscoat # 150D) was used as the cyclic ether-containing monomer instead of the tetrahydrofurfuryl acrylate. I got a sheet.

(Example 5)
As a cyclic ether-containing monomer, instead of 25 parts by mass of 3-ethyl-3-oxetanyl methyl acrylate (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (MEDOL-10, manufactured by Osaka Organic Chemical Industry Co., Ltd.) Using 10 parts by mass, bisphenol A ethylene oxide-modified diacrylate as a polyfunctional monomer Instead of 12 parts by mass, bisphenol A EO (3.8) adduct diacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., biscoat # 700HV) An 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)
(2-Methyl-2-ethyl-1,3-dioxolan-4-yl) Cyclic trimethylolpropaneformal acrylate (Viscoat # 200, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 10 parts by mass of methyl acrylate. Obtained an adhesive sheet with a release sheet in the same manner as in Example 5.

(Example 7)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the blending amount of the pigment was changed so that the content of the colorant was 0.20 parts by mass.

(Example 8)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the blending amount of the pigment was changed so that the content of the colorant was 0.06 parts by mass.

(Example 9)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the blending amount of the pigment was changed so that the content of the colorant was 0.53 parts by mass.

(Example 10)
<Preparation of Adhesive Composition (A-2)>
0.2 parts by mass of a tolylene diisocyanate compound (Coronate L-55E, manufactured by Toso Co., Ltd.) as a cross-linking agent with respect to 100 parts by mass of the crosslinkable acrylic copolymer (a-1) produced in Synthesis Example 1, a silane cup. 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry 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. , Viscoat # 192) by 25 parts by mass, bisphenol A ethylene oxide-modified diacrylate (manufactured by Toa Synthetic Co., Ltd., Aronix M211B) as a polyfunctional monomer by 12 parts by mass, and bis (2,4,6-) as a photopolymerization initiator. 1.0 part by mass of trimethylbenzoyl) phenylphosphine oxide (BASF Japan, IRGACURE819) was added, and as a colorant, copper-iron-manganese oxide pigment (Dainichi Seika Kogyo), TM Black 3550. ) Was added in an amount of 0.15 part, and ethyl acetate was added as a solvent so that the solid content concentration became 35% by mass to obtain a semi-cured pressure-sensitive adhesive composition (A-2).

<Preparation of adhesive layer (A-2)>
Next, as the first release sheet, a 100 μm-thick polyethylene terephthalate film having an easy-adhesive layer treated with a silicone-based release agent (heavy separator film, manufactured by Teijin DuPont Film Co., Ltd., release-treated polyethylene terephthalate film). ) Was prepared. The pressure-sensitive adhesive composition (A-2) is uniformly applied to the surface of the first release sheet on the side of the easy-adhesive layer so that the coating thickness after drying is 150 μm, and the pressure-sensitive adhesive is applied. After preparing the coating film of the composition (A-2), the pressure-sensitive adhesive layer (A-2) is formed on the surface of the first release sheet by drying in an air circulation type constant temperature oven at 90 ° C. for 3 minutes. did.

Next, a second release sheet (light separator film, manufactured by Teijin DuPont Film Co., Ltd., which has been released from the first release sheet) having a thickness of 75 μm and which has been subjected to a release treatment having higher release properties than the first release sheet is prepared. did. The second release sheet was laminated on the pressure-sensitive adhesive layer (A-2) formed on the surface of the first release sheet. As a result, the adhesive layer (A-2) is sandwiched between a pair of release sheets having different peeling forces, and the composition of the first release sheet / adhesive layer (A-2) / second release sheet is peeled off. An adhesive sheet with a sheet was obtained. The 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 11)
Adhesion with a release sheet in the same manner as in Example 10 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. I got a sheet.

(Example 12)
As the 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.) is used instead of 25 parts by mass of phenoxyethyl acrylate, and a polyfunctional single amount is used. With a release sheet in the same manner as in Example 10 except that 6 parts by mass of bisphenol F EO modified diacrylate (Aronix M208, manufactured by Toa Synthetic Co., Ltd.) was used instead of 12 parts by mass of bisphenol A ethylene oxide modified diacrylate as the body. An adhesive sheet was obtained.

(Example 13)
As a chain ether-containing monomer, an acrylate having a 2- [2- (ethoxy) ethoxy] ethyl structure (Viscoat # 190D, manufactured by Osaka Organic Chemical Industry Co., Ltd.) is used instead of 2- [2- (ethoxy) ethoxy] ethyl acrylate. An adhesive sheet with a release sheet was obtained in the same manner as in Example 12 except that it was used.

(Example 14)
10 parts by mass of methoxytriethylene glycol acrylate (Viscoat MTG manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 25 parts by mass of phenoxyethyl acrylate as the chain ether-containing monomer, and bisphenol A ethylene oxide-modified didi was used as the polyfunctional monomer. A release sheet in the same manner as in Example 10 except that 10 parts by mass of bisphenol A EO (3.8) adduct diacrylate (Viscoat # 700HV, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 12 parts by mass of acrylate. An adhesive sheet with an adhesive was obtained.

(Example 15)
An adhesive sheet with a release sheet was obtained in the same manner as in Example 14 except that 10 parts by mass of methoxypolyethylene glycol acrylate (Viscoat MPE400A manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used instead of 10 parts by mass of methoxytriethylene glycol acrylate. ..

(Example 16)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 10 except that the blending amount of the pigment was changed so that the content of the colorant was 0.20 parts by mass.

(Example 17)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 10 except that the blending amount of the pigment was changed so that the content of the colorant was 0.06 parts by mass.

(Example 18)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 10 except that the blending amount of the pigment was changed so that the content of the colorant was 0.53 parts by mass.

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

(Comparative Example 2)
Adhesive sheet with 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 3-1)
An adhesive sheet with a release sheet was obtained in the same manner as in Example 1 except that no colorant was added.

(Comparative Example 3-2)
An adhesive sheet with a release sheet was obtained in the same manner as in Example 10 except that no colorant was added.

(Comparative Example 4)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Comparative Example 1 except that the blending amount of the pigment was changed so that the content of the colorant was 1.2 parts by mass.

(Comparative Example 5)
Trimethylolpropane-modified tolylene diisocyanate (BHS8515, manufactured by Toyochem Co., Ltd.) 0.15 mass by mass as a cross-linking agent with respect to 100 parts by mass of the crosslinkable (meth) acrylic copolymer (b-1) produced in Synthesis Example 2-1. Parts, 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd., KBM-403) as a silane coupling agent, and copper-iron-manganese oxide-based pigment as a colorant ( Add 0.15 part of TM Black 3550) manufactured by Dainichi Seika Kogyo Co., Ltd., and add methyl ethyl ketone as a solvent so that the solid content concentration becomes 35% by mass to obtain the pressure-sensitive adhesive composition (B-1). Obtained. Next, in the method for producing the pressure-sensitive adhesive layer (A-1) of Example 1, 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). An adhesive sheet with a release sheet was obtained in the same procedure as the production method of (A-1). The pressure-sensitive adhesive sheet with a release sheet had a pressure-sensitive adhesive layer (B-1).

(Comparative Example 6)
0.3 mass by mass of an isocyanate-based cross-linking agent (Takenate D110N, manufactured by Mitsui Chemicals, Inc.) as a cross-linking agent with respect to 100 parts by mass of the cross-linkable (meth) acrylic copolymer (b-2) produced in Synthesis Example 2-2. 0.2 parts by mass of a polyol (EDP-300 manufactured by Adeca Co., Ltd.) in which propylene oxide is added to ethylenediamine as a cross-linking accelerator, and 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd.) as a silane coupling agent. KBM-403) 0.15 weight and 0.15 parts of copper, iron, manganese oxide pigment (manufactured by Dainichi Seika Kogyo), TM Black 3550) were added as colorants, and the solid content concentration was 30. Ethyl acetate was added as a solvent so as to be in mass%, and a pressure-sensitive adhesive composition (B-2) was obtained. Next, 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 except that the conditions were changed to dry in an air circulation type constant temperature oven for 1 minute and then further dried at 155 ° C. for 1 minute, and the aging treatment was changed to treatment at 23 ° C. for 120 hours. ) Was obtained in the same procedure as the method for producing). This pressure-sensitive adhesive sheet with a release sheet had a pressure-sensitive adhesive layer (B-2).

<Outgas resistance evaluation>
(Test Example 1-1)
The outgas resistance evaluation was carried out as follows using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 18 and Comparative Examples 2, 3-1 and 3-2. 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 a polycarbonate resin plate having a thickness of 1 mm (a bread manufactured by Teijin Corporation) is used as the first member with respect to the pressure-sensitive adhesive layer. It was attached to the 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 exposed adhesive layer on the entire surface as a second member. As a result, a laminate sample composed of a polycarbonate resin plate / adhesive layer / glass plate was obtained. After treating the laminated sample in an autoclave at 40 ° C. and 0.5 MPa for 30 minutes, ultraviolet rays are irradiated from the glass plate side so that the integrated light intensity is 3000 mJ / cm ^2, and a test having a size of 100 mm × 200 mm is performed. A sample was obtained. 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, floats, and peeling were evaluated according to the following three criteria. ..
A: No bubbles, floats or peeling were observed after 2 hours and 100 hours.
B: Microbubbles were observed after 2 hours, but no bubbles, floats or peeling were observed after 100 hours.
C: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 1-2)
As the pressure-sensitive adhesive sheet with the release sheet, the pressure-sensitive adhesive sheet with the release sheet prepared in Comparative Examples 1, 4, 5, and 6 was used, and the laminated sample was not irradiated with ultraviolet rays. Test samples were obtained in a similar manner. The test sample was visually observed, and air bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 1-1.

(Test Example 2-1)
The outgas resistance evaluation was carried out as follows using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 18 and Comparative Examples 2, 3-1 and 3-2. 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 a polycarbonate resin plate with a hard coat (Mitsubishi Gas) having a thickness of 1 mm is used as the first member for the pressure-sensitive adhesive layer. It was attached to the side of the Iupilon sheet MR-58U manufactured by Kagaku Co., Ltd. without the hard coat layer. 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 exposed adhesive layer on the entire surface as a second member. As a result, a laminate sample composed of a polycarbonate resin plate / adhesive layer / glass plate was obtained. After treating the laminated sample in an autoclave at 40 ° C. and 0.5 MPa for 30 minutes, ultraviolet rays are irradiated from the glass plate side so that the integrated light intensity is 3000 mJ / cm ^2, and a test having a size of 100 mm × 200 mm is performed. A sample was obtained. 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, floats, and peeling were evaluated according to the following three criteria. ..
A: No bubbles, floats or peeling were observed after 2 hours and 100 hours.
B: Microbubbles were observed after 2 hours, but no bubbles, floats or peeling were observed after 100 hours.
C: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 2-2)
As the pressure-sensitive adhesive sheet with the release sheet, the pressure-sensitive adhesive sheet with the release sheet prepared in Comparative Examples 1, 4, 5, and 6 was used, and the laminated sample was not irradiated with ultraviolet rays. Test samples were obtained in a similar manner. The test sample was visually observed, and air bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 2-1.

(Test Example 3-1)
The outgas resistance evaluation was carried out as follows using the pressure-sensitive adhesive sheets with release sheets prepared in Examples 1 to 18 and Comparative Examples 2, 3-1 and 3-2. 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 (manufactured by Oike Kogyo Co., Ltd.) is used as a second member for the pressure-sensitive adhesive layer. KB300) was pasted together. Next, the first release sheet, which is a heavy separator film, is 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 is used as the first member for the exposed adhesive layer. (Acrylic MR-200 manufactured by Mitsubishi Rayon Co., Ltd.) was attached to the entire surface. As a result, a laminate sample composed of a polymethylmethacrylate resin plate / adhesive layer / ITO film was obtained. After treating the laminated sample in an autoclave at 40 ° C. and 0.5 MPa for 30 minutes, ultraviolet rays are irradiated from the glass plate side so that the integrated light intensity is 3000 mJ / cm ^2, and a test having a size of 100 mm × 200 mm is performed. A sample was obtained. 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, floats, and peeling were evaluated according to the following three criteria. ..
A: No bubbles, floats or peeling were observed after 2 hours and 100 hours.
B: Microbubbles were observed after 2 hours, but no bubbles, floats or peeling were observed after 100 hours.
C: Bubbles, floating and peeling were observed after 2 hours and 100 hours.

(Test Example 3-2)
As the pressure-sensitive adhesive sheet with the release sheet, the pressure-sensitive adhesive sheet with the release sheet prepared in Comparative Examples 1, 4, 5, and 6 was used, and the laminated sample was not irradiated with ultraviolet rays. Test samples were obtained in a similar manner. The test sample was visually observed, and air bubbles, floating and peeling were evaluated according to the same criteria as in Test Example 3-1.

<Optical characteristics>
The light peeling separator, which is the second peeling sheet, was peeled off, and a PET film (Cosmo Shine A4300 # 100 manufactured by Toyobo Co., Ltd.) was laminated in place of the peeled separator to prepare a laminated film. The laminated film was cut into a size of 50 mm in width and 50 mm in length, and the first release sheet was peeled off. Next, the exposed adhesive surface was attached to a slide glass (manufactured by Matsunami Glass Co., Ltd., S9112) using a hand roller. In this state, it was held in an autoclave under the conditions of 40 ° C. and 5 atm for 30 minutes to be brought into close contact with the glass plate.
The total light transmittance and haze of the obtained laminate were measured using an integrating sphere type light transmittance measuring device (NDH-5000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K 7150.

<Design>
A sample was prepared in the same manner as the optical characteristic measurement, and evaluated by placing it on a display displaying a black screen.
A: It looked blacker than when nothing was put on it. B: No change

<Visibility>
A sample was prepared in the same manner as in the optical characteristic measurement, the brightness of the display displaying characters was adjusted to 500 nits, and the evaluation was made according to the following criteria. In addition, it is practically preferable that the visibility is evaluated as ◯.
A: No bleeding or blurring B: Bleeding or blurring but characters can be read C: Blurring or blurring and characters cannot be read

(Evaluation results)
Table 1 shows Examples 1 to 9, Table 2 shows Examples 10 to 18, and Table 3 shows the evaluation results of outgas resistance, design, and visibility of Comparative Examples. From the comparison between the adhesive sheets obtained in Examples 1 to 9 and 10 to 18 and the adhesive sheets obtained in Comparative Examples 1, 2 and 4, the adhesive sheets obtained in Examples 1 to 9 and 10 to 18 It was found that the film has excellent outgas resistance, and particularly excellent outgas resistance even for a polycarbonate film having no hard coat layer. Further, Examples 1 to 9 and 10 to 18 and Comparative Examples 3 to 1 to 9 and 10 to 18 are excellent in design, and comparison between Examples 1 to 9 and 10 to 18 and Comparative Example 6 shows that all light rays. It was found that the visibility was inferior when the value obtained by dividing the transmittance by the haze was out of the range of 0.5 to 120.

Claims

An adhesive sheet with 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, a photopolymerization initiator, and a colorant.
The crosslinked (meth) acrylic copolymer has a structure in which the crosslinkable (meth) acrylic copolymer is crosslinked with a crosslinking agent.
The polymerizable monomer is a pressure-sensitive adhesive sheet containing at least one of a monofunctional monomer having a cyclic ether structure and a monofunctional monomer having a chain ether structure.
The adhesive sheet according to claim 1, wherein the value obtained by dividing the total light transmittance by the haze value is 0.5 to 120 or less.
The adhesive sheet according to any one of claims 1 or 2, wherein the total light transmittance is 5 to 90%.
The adhesive sheet according to any one of claims 1 to 3, wherein the haze is 0.1 to 15%.
The monofunctional monomer having a cyclic ether structure is contained in any one of claims 1 to 4 in an amount of 5 to 30 parts by mass with respect to 100 parts by mass of the crosslinkable (meth) acrylic copolymer. Adhesive sheet.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the cyclic ether structure is a 4- to 6-membered ring.
The monofunctional monomer having a chain ether structure is contained in any one of claims 1 to 4 and 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. Adhesive sheet.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the colorant is at least one selected from metal oxide and carbon black.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the colorant is a metal oxide.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the primary average particle size of the colorant is 0.01 μm or more and less than 5 μm.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, 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 any one of claims 1 to 11, wherein the polyfunctional monomer has a bisphenol skeleton in the molecule.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 12, 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 sheet according to any one of claims 1 to 13, 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 14, which is used for bonding the first member to one type of second member selected from the group consisting of a glass plate, a resin film, and a resin plate.
A laminate comprising the adhesive sheet according to any one of claims 1 to 15 or a cured product thereof.
The laminated body according to claim 16, further comprising a resin molded body, and having a structure in which the resin molded body and a layer of the pressure-sensitive adhesive sheet or a cured product thereof are laminated.