JP2023083035A - Pressure sensitive adhesive sheet for flexible display, and methods of producing flexible display and laminate - Google Patents

Abstract

To provide: an adhesive sheet capable of forming a flexible display that is not only more flexible than conventional sheets but also excellent in dust resistance and resistance to improper rolling; and an adhesive sheet that can be used in applications requiring more severe flexibility, such as rollable displays, because of its superior strain suitability.SOLUTION: A pressure sensitive adhesive sheet for a flexible display has an acrylic pressure sensitive adhesive agent layer on a release agent layer of an antistatic-treated release film. The surface resistance of the release agent layer in the 23°C-50%RH atmosphere is 1×1011 Ω/sq. or less. In the release agent layer, a main component is linear silicone, and the content of branched silicone is 1 mass% or less. The acrylic pressure sensitive adhesive agent layer has a glass transition temperature of -55°C or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet used to form a flexible display, a laminate having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive sheet, and a flexible display.

2. Description of the Related Art In recent years, input devices using a combination of an image display device such as a liquid crystal display (LCD) or an organic electroluminescence (organic EL) display (OLED) and a touch panel have become widespread. A transparent conductive film used for a touch panel is laminated on a member such as support glass via an adhesive layer. A polarizing plate film used in an image device is attached to a liquid crystal module or an organic EL module via an adhesive layer.

As the image display device, a flat display using a glass substrate has been the mainstream, but in recent years, a foldable display and a rollable display using a flexible substrate such as plastic have been developed. , flexible displays have been developed. Such flexible displays have various advantages over conventional flat displays using glass substrates, such as being superior in light weight, thinness, flexibility, etc., as well as being superior in design. have.

The pressure-sensitive adhesive sheet has hitherto been required to have a property that does not cause foaming or peeling in a high-temperature environment or a high-temperature and high-humidity environment. In terms of flexibility, in the case of products on the market, it is becoming a basic performance to have flexibility so that they can be used in foldable displays. However, although attempts have been made to improve the flexibility at a specific point, there has been no improvement in the adhesive sheet that simultaneously satisfies the flexibility at a plurality of points. Flexibility is required to have properties that do not cause foaming, lifting, or peeling when repeatedly bent.

In order to solve these problems, Patent Document 1 discloses a pressure-sensitive adhesive containing a base polymer, a photocurable compound, and a photoinitiator. Further, Patent Document 2 discloses a flexible device carrier sheet having an antistatic base material, an adhesive layer, and a release sheet.

JP 2020-097737 A JP 2018-203873 A

Furthermore, in recent years, a rollable display has attracted attention as a more advanced display. Adhesive sheets used in rollable displays are required to have a stricter flexibility than before.In addition to flexibility at a specific point (foldable flexibility), multiple There is also a demand for strain aptitude that can withstand bendability (rollable bendability) at specific points. In addition, in rollable displays, there is a high level of market demand for dust resistance that does not allow dust or dirt to enter, so that the clearness of displayed images can be directly viewed. In addition, when the adhesive sheet is mass-produced, when the adhesive sheet is cured in a roll-to-roll state, there is a possibility that the sharpness of image quality may be impaired due to positional deviation (winding deviation) in the shearing direction of the adhesive layer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet capable of forming a flexible display which not only has better flexibility than conventional ones, but also has excellent winding misalignment resistance and dust resistance.
Another object of the present invention is to provide a pressure-sensitive adhesive sheet that can be applied to applications that require more severe flexibility, such as rollable displays, because of its excellent strain aptitude.

As a result of extensive studies, the present inventors have found that the following aspects can solve the problems of the present invention, and have completed the present invention.
That is, in the present invention, an acrylic pressure-sensitive adhesive layer is provided on the release agent layer of the antistatic release film, and the surface resistance value of the release agent layer under an atmosphere of 23° C.-50% RH is 1×10 ¹¹ Ω/□. below, the release agent layer has a linear silicone as a main component and a branched silicone content of 1% by mass or less, and the acrylic pressure-sensitive adhesive layer has a glass transition temperature of −55° C. or less. The present invention relates to a pressure-sensitive adhesive sheet for a flexible display.
The present invention also relates to the pressure-sensitive adhesive sheet for a flexible display, wherein the acrylic pressure-sensitive adhesive layer has a thickness of 50 μm or more.
Further, in the present invention, the acrylic pressure-sensitive adhesive layer contains an acrylic copolymer (A), and the acrylic copolymer (A) has a mass average molecular weight of 800,000 or more. It is related with the said adhesive sheet for flexible displays.
Further, in the present invention, the acrylic copolymer (A) comprises a (meth)acrylic acid alkyl ester monomer (a-1) having an alkyl group having 1 or 2 carbon atoms, and a (meth)acrylic acid having an alicyclic structure. The adhesive sheet for a flexible display is a copolymer of a monomer mixture containing at least one of the alkyl ester monomers (a-2).
Further, in the present invention, the monomer mixture further contains a (meth)acrylic acid alkyl ester monomer (a-3) having an alkyl group having 8 to 12 carbon atoms, and the content of the monomer (a-3) is a monomer The pressure-sensitive adhesive sheet for a flexible display, which is 80% by mass or more in 100% by mass of the mixture. Regarding.
Further, in the present invention, the acrylic pressure-sensitive adhesive layer contains an antistatic agent, and the acrylic pressure-sensitive adhesive layer has a surface resistance value of 1×10 ¹⁰ Ω/□ or less in an atmosphere of 23° C.-50% RH. It is related with the adhesive sheet for flexible displays.
The present invention also provides a method for producing a laminate comprising an adherend and an acrylic pressure-sensitive adhesive layer, wherein the antistatic release film is peeled from the pressure-sensitive adhesive sheet for a flexible display, and the step of affixing it to the adherend. and relates to a method for manufacturing a laminate.
The present invention also provides a method for manufacturing a flexible display having a flexible image display portion and an acrylic pressure-sensitive adhesive layer, wherein the antistatic treatment release film is peeled from the pressure-sensitive adhesive sheet for a flexible display, and a flexible image display is performed. The present invention relates to a method for manufacturing a flexible display, including a step of attaching to a part.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet capable of forming a flexible display that not only has better flexibility than conventional ones, but also has excellent winding misalignment resistance and dust resistance.
In addition, it can be applied to applications that require more severe flexibility, such as rollable displays. By using the adhesive sheet of the present invention, it is possible to make it small when stored and a large screen when used to improve visibility. It is possible to provide an excellent flexible display.

1 is a schematic cross-sectional view partially showing the pressure-sensitive adhesive sheet of the present invention; FIG. 1 is a schematic cross-sectional view partially showing a laminate, which is an example of use of the pressure-sensitive adhesive sheet of the present invention. FIG. 1 is a schematic cross-sectional view partially showing a display, which is an example of use of the pressure-sensitive adhesive sheet of the present invention. FIG.

Hereinafter, configuration examples of the pressure-sensitive adhesive sheet, laminate, and display of the present invention will be described, but the present invention is not limited thereto.

Definitions of terms used herein. (Meth)acrylic acid ester includes acrylic acid ester and methacrylic acid ester. A monomer is an ethylenically unsaturated group-containing monomer. The adherend refers to the other party to which the pressure-sensitive adhesive sheet is attached. In the present invention sheet, film and tape are synonymous and "RH" means relative humidity.
In the present specification, "acrylic copolymer (A)" is referred to as "copolymer (A)", "adhesive for flexible displays" is referred to as "adhesive", and "an alkyl group having 1 or 2 carbon atoms is (meth)acrylic acid alkyl ester monomer (a1) having an alicyclic structure is referred to as "monomer (a1)", "(meth)acrylic acid alkyl ester monomer (a2) having an alicyclic structure" is referred to as "monomer (a2)", and "carbon number A (meth)acrylic acid alkyl ester monomer (a3) having 8 to 12 alkyl groups" is referred to as "monomer (a3)", and a "monomer having a hydroxy group or a monomer (a4) having a carboxy group" is referred to as "monomer (a4 )” and “another monomer (a5) copolymerizable with the monomers (a-1) to (a-4)” are sometimes referred to as “monomer (a5)”.
In addition, unless otherwise noted, the various components appearing in the present specification may be used singly or in combination of two or more.

"adhesive sheet"
The pressure-sensitive adhesive sheet of the present invention comprises an acrylic pressure-sensitive adhesive layer on a release agent layer of an antistatic release film, and is used to form a flexible display.
The antistatic treatment release film is provided with an antistatic layer on one or both sides of the film substrate, further on the top surface of the antistatic layer, and on the film substrate on the side not provided with the antistatic layer. In addition, it is a film provided with a release agent layer.
It can be formed by applying an adhesive on the release layer of the antistatic release film by a known method.

<Acrylic adhesive layer>
The glass transition temperature (Tg) of the acrylic pressure-sensitive adhesive layer is −55° C. or lower as a result of differential scanning calorimetry (DSC) of the pressure-sensitive adhesive layer. It is preferably -57°C or lower, more preferably -60°C or lower. When the glass transition temperature of the acrylic pressure-sensitive adhesive layer is −55° C., sufficient strain aptitude can be exhibited.
The acrylic pressure-sensitive adhesive layer is formed by forming a thin film of an acrylic pressure-sensitive adhesive containing an acrylic copolymer (A), a curing agent, additives, etc., on a release film by a known method. is a sheet.
The acrylic pressure-sensitive adhesive layer preferably contains an acrylic copolymer having a mass average molecular weight of 800,000 or more as the acrylic copolymer (A). Moreover, it is preferable to contain an antistatic agent.

(Acrylic copolymer (A))
Acrylic copolymer (A) is a copolymer of a monomer mixture.
Monomers constituting the acrylic copolymer (A) can be classified into the following monomers (a-1) to (a-5).

(a-1) A (meth)acrylic acid alkyl ester monomer having an alkyl group having 1 or 2 carbon atoms (a-2) A (meth)acrylic acid alkyl ester monomer having an alicyclic structure (a-3) C8 to A (meth)acrylic acid alkyl ester monomer having 12 alkyl groups (a-4) a monomer having a hydroxy group, or a monomer having a carboxy group (a-5) together with the monomers (a-1) to (a-4) Other polymerizable monomers

The acrylic copolymer (A) is a copolymer of a monomer mixture containing at least one of the monomer (a-1) and the monomer (a-2), and is a substituent that produces cohesion in the side chain. will have This is preferable because a PSA sheet having excellent flexibility and adhesive strength can be obtained.

The content of monomer (a-1) and monomer (a-2) is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, based on 100% by mass of the monomer mixture. When both the monomer (a-1) and the monomer (a-2) are contained, the total amount is preferably 1 to 30% by mass, preferably 2 to 20% by mass, based on 100% by mass of the monomer mixture. is more preferred.
When the content is 1% by mass or more, it is easy to obtain sufficient stress cohesion. In addition, it is preferable that the content is 30% by mass or less because it becomes easy to achieve both cohesion and relaxation.

[Monomer (a-1)]
Monomer (a-1) is a (meth)acrylic acid alkyl ester monomer having an alkyl group having 1 or 2 carbon atoms, specifically methyl (meth)acrylate, ethyl (meth)acrylate, or the like. mentioned. Among them, methyl (meth)acrylate is preferable from the viewpoint of flexibility and adhesive strength.

[Monomer (a-2)]
Monomer (a-2) is a (meth)acrylic acid alkyl ester monomer having an alicyclic structure, and specific examples thereof include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. is mentioned. Among them, isobornyl (meth)acrylate is preferable from the viewpoint of flexibility and adhesive strength.

[Monomer (a-3)]
Monomer (a-3) is a (meth)acrylic acid alkyl ester monomer having an alkyl group having 8 to 12 carbon atoms, specifically, octyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylate ) 2-ethylhexyl acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate and the like. Among them, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate are preferable from the viewpoint of flexibility.

Furthermore, when a (meth)acrylic acid alkyl ester monomer (a-3) having an alkyl group having 8 to 12 carbon atoms is used, the relaxation property of the adhesive is improved, a tough adhesive layer is obtained, and flexibility is improved. It is more preferable because it can

The content of the monomer (a-3) is preferably 50 to 98% by mass, more preferably 65 to 98% by mass, even more preferably 80 to 95% by mass, based on 100% by mass of the monomer mixture.
When the content is 50% by mass or more, it is easy to obtain sufficient relaxation properties. In addition, the content of the monomer (a-1) or monomer (a-2) that produces cohesive force by having a content of 98% by mass or less and the content of monomer (a-4) that creates cross-linking points are secured and relaxed. It is preferable because it becomes easier to achieve both properties and cohesive strength.

[Monomer (a-4)]
Monomer (a-4) is a monomer having a hydroxy group or a monomer having a carboxy group.

A monomer having a hydroxy group is not limited as long as it is a monomer having a hydroxy group in the molecule, and specifically, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (meth)acrylate 3-hydroxypropyl acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Among them, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable from the viewpoint of cohesive strength and adhesive strength.

Carboxy group-containing monomers are not limited as long as they have a carboxy group in the molecule, and specific examples include (meth)acrylic acid, p-carboxybenzyl acrylate, β-carboxyethyl acrylate, maleic acid, mono ethyl maleic acid, itaconic acid, citraconic acid, fumaric acid and the like. Among them, (meth)acrylic acid is preferable from the viewpoint of cohesive strength and adhesive strength.

Further, the inclusion of the monomer (a-4) is more preferable because the cohesive force of the adhesive is improved, a tough adhesive layer is obtained, and the adhesive strength can be improved.

The content of the monomer (a-4) is preferably 0.5 to 2.5% by mass, more preferably 0.5 to 2.0% by mass, per 100% by mass of the monomer mixture. When both a monomer having a hydroxy group and a monomer having a carboxy group are contained, the total amount is preferably 0.5 to 2.5% by mass in 100% by mass of the monomer mixture, and 0.5% by mass. ~2.0% by mass is more preferred.
When the content is 0.5% by mass or more, sufficient cohesive force can be easily obtained, and when the content is 2.5% by mass or less, both cohesive force and relaxation properties can be easily achieved, which is preferable.
Containing both a monomer having a hydroxy group and a monomer having a carboxy group is preferable from the viewpoint of making it easier to achieve both cohesive strength and relaxation properties than when each of them is contained alone.

[Monomer (a-5)]
The monomer (a-5) is another monomer copolymerizable with the monomers (a-1) to (a-4), and the acrylic pressure-sensitive adhesive (A) of the present invention comprises the monomers (a-1) to In addition to (a-4), it may further contain a monomer (a-5).
Monomer (a-5) is a (meth)acrylic acid alkyl ester monomer other than monomers (a-1) to (a-3), a (meth)acrylic acid monomer having an epoxy group, and a (meth)acrylic acid having an amino group. Examples thereof include acid monomers, monomers having an alkyleneoxy group, and other vinyl monomers.

Examples of (meth)acrylic acid alkyl ester monomers other than monomers (a-1) to (a-3) include propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, and (meth)acrylate. Hexyl acrylate and the like can be mentioned.

Monomers having an epoxy group include, for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 6-methyl-3,4-(meth)acrylate epoxycyclohexylmethyl and the like.

Examples of monomers having an amino group include (meth)acrylates such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate. ) acrylic acid monoalkylamino esters, and the like.

Examples of monomers having an alkyleneoxy group include monomers represented by the following general formula (1) and monomers represented by general formula (2).

In general formula (1) and general formula (2), R ₁ and R ₂ are each independently a hydrogen atom or a methyl group, n and m are integers representing repeating units, 1 ≤ n ≤ 25, 1 ≤ m ≤25, preferably 1≤n≤13 and 1≤m≤5.

Commercial products of the monomer represented by general formula (1) include, for example, methoxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.: in the above formula (1), R ₁ is a hydrogen atom, n = 1), methoxydiethylene glycol acrylate (Osaka organic Chemical Industry Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n = 2), methoxytriethylene glycol acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n = 3), methoxy polyethylene glycol # 400 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: in the above formula (1), R ₁ is a hydrogen atom, n = 9), methoxy polyethylene glycol # 600 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n = 13), methoxypolyethylene glycol #1000 acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n = 23), Methoxydiethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: in the above formula (1), R ₁ is a methyl group, n = 2), methoxytriethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: in the above formula (1), R ₁ is a methyl group, n = 3), methoxytetraethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: in the above formula (1), R ₁ is a methyl group, n = 4), methoxypolyethylene glycol # 400 methacrylate (Shin-Nakamura Chemical Industry Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n = 9), methoxypolyethylene glycol #600 methacrylate (Shin-Nakamura Chemical Co., Ltd.: In the above formula (1), R ₁ is a hydrogen atom, n=13), and methoxypolyethylene glycol #1000 methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: in the above formula (1), _R1 is a hydrogen atom, n=23).

Commercially available monomers represented by formula (2) include, for example, methoxytripropylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.; in formula (2) above, _R2 is a hydrogen atom and m=3).

Vinyl monomers include, for example, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, and the like.

The content of the monomer (a-5) is preferably 100% by mass of the monomer mixture and 5 to 50% by mass. When the content is 5% by mass or more, the cohesive force is improved. Moreover, when the content is 50% by mass or less, it is preferable because it is easy to achieve both cohesive strength and flexibility.

[Production of acrylic copolymer (A)]
The acrylic copolymer (A) can be produced by polymerizing a monomer mixture. Polymerization can be carried out by known polymerization methods such as solution polymerization, bulk polymerization, emulsion polymerization and suspension polymerization, but solution polymerization is preferred. Solvents used in solution polymerization are preferably acetone, methyl acetate, ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone, cyclohexanone, and the like. The polymerization temperature is preferably 60 to 120°C for boiling point reaction. The polymerization time is preferably about 5 to 12 hours.

The polymerization initiator used for polymerization is preferably a radical polymerization initiator. Radical polymerization initiators are generally peroxides and azo compounds. Peroxides are, for example, di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5- Dialkyl peroxides such as di(t-butylperoxy)hexyne-3; t-butylperoxybenzoate, t-butylperoxyacetate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane Peroxy esters; ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl-4,4-bis(t-butylperoxy ) peroxyketals such as barate; hydroperoxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide; benzoyl peroxide, decanoyl peroxide, diacyl peroxides such as lauroyl peroxide and 2,4-dichlorobenzoyl peroxide; and peroxydicarbonates such as bis(t-butylcyclohexyl)peroxydicarbonate.

2,2'-azobisbutyronitrile such as 2,2'-azobisisobutyronitrile (abbreviation: AIBN), 2,2'-azobis(2-methylbutyronitrile); 2,2′-azobisvaleronitrile such as ,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile); - 2,2'-azobispropionitrile such as azobis(2-hydroxymethylpropionitrile); 1,1'-azobis-1-alkanes such as 1,1'-azobis(cyclohexane-1-carbonitrile) Nitrile etc. are mentioned.

The polymerization initiator is preferably used in an amount of 0.01 to 10 parts by mass, more preferably 0.05 to 2 parts by mass, based on 100 parts by mass of the monomer mixture.

[Mass average molecular weight (Mw)]
The mass average molecular weight of the copolymer (A) is preferably 600,000 to 2,000,000, more preferably 800,000 to 1,800,000, and even more preferably 1,000,000 to 1,500,000. When it is in the range of 600,000 to 2,000,000, the cohesive strength is further improved, and the flexibility such as anti-displacement property and strain suitability, and adhesive strength are further improved. In addition, a mass average molecular weight is a value of polystyrene conversion measured by gel permeation chromatography (GPC) method.

(curing agent)
The curing agent reacts with hydroxy groups and/or carboxy groups of the copolymer (A) to improve the cohesive strength of the pressure-sensitive adhesive layer, thereby improving flexibility and adhesive strength.

Curing agents include isocyanate compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, metal chelates, and the like. Among these, it is preferable to use an isocyanate compound as the curing agent because the flexibility can be improved.

An isocyanate compound is an isocyanate having two or more isocyanate groups. Isocyanate compounds are preferably isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates and alicyclic polyisocyanates, and burettes, nurates and adducts thereof.

Aromatic polyisocyanates are, for example, 1,3-phenylene diisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6- tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanatobenzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4 ''-triphenylmethane triisocyanate and the like.

Aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.

Aroaliphatic polyisocyanates are, for example, ω,ω′-diisocyanate-1,3-dimethylbenzene, ω,ω′-diisocyanate-1,4-dimethylbenzene, ω,ω′-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Alicyclic polyisocyanates include, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4 -cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), 1,4-bis(isocyanatomethyl)cyclohexane and the like.

The burette body is a self-condensed product having a burette bond formed by self-condensation of an isocyanate monomer. The burette body includes, for example, a burette body of hexamethylene diisocyanate.

The nurate compound is a trimer of isocyanate monomers. Examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate, and the like.

The adduct is a bifunctional or higher isocyanate compound obtained by reacting an isocyanate monomer and a bifunctional or higher low-molecular-weight active hydrogen-containing compound. Adducts include, for example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate, a compound obtained by reacting trimethylolpropane and tolylene diisocyanate, a compound obtained by reacting trimethylolpropane and xylylene diisocyanate, trimethylol A compound obtained by reacting propane with isophorone diisocyanate, a compound obtained by reacting 1,6-hexanediol with hexamethylene diisocyanate, and the like can be mentioned.

The isocyanate compound is preferably a trifunctional isocyanate compound from the viewpoint of forming a sufficient crosslinked structure. The isocyanate compound is more preferably an adduct or a nurate which is a reaction product of an isocyanate monomer and a trifunctional low-molecular-weight active hydrogen-containing compound. Isocyanate compounds include trimethylolpropane adduct of hexamethylene diisocyanate, nurate of hexamethylene diisocyanate, trimethylolpropane adduct of tolylene diisocyanate, nurate of tolylene diisocyanate, trimethylolpropane adduct of isophorone diisocyanate, and isophorone diisocyanate. A nurate compound is preferred, and a trimethylolpropane adduct of hexamethylene diisocyanate, a trimethylolpropane adduct of tolylene diisocyanate, and a trimethylolpropane adduct of isophorone diisocyanate are more preferred.

Epoxy compounds include, for example, glycerol diglycidyl ether, 1,6-hexanediol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'- diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidylaminophenylmethane and the like.

Aziridine compounds include, for example, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxite), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, 4, 4'-bis(ethyleneiminocarbonylamino)diphenylmethane and the like.

The carbodiimide compound is preferably a high-molecular-weight polycarbodiimide produced by a decarboxylation condensation reaction of a diisocyanate compound in the presence of a carbodiimidation catalyst. Carbodilite series manufactured by Nisshinbo Co., Ltd. is preferable as the commercial product of the high-molecular-weight polycarbodiimide. Among them, Carbodilite V-03, 07 and 09 are preferable because of their excellent compatibility with organic solvents.

Metal chelates are preferably coordination compounds of polyvalent metals such as, for example, aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium, with acetylacetone or ethyl acetoacetate. Examples of metal chelates include aluminum ethylacetoacetate/diisopropylate, aluminum trisacetylacetonate, aluminum bisethylacetoacetate/monoacetylacetonate, and aluminum alkylacetoacetate/diisopropylate.

The curing agent is preferably contained in an amount of 0.01 to 1.0 parts by mass, more preferably 0.03 to 0.5 parts by mass, based on 100 parts by mass of the copolymer (A). When the content is 0.01 parts by mass or more, the cohesive force is further improved, and when the content is 4 parts by mass or less, cohesive force and flexibility are easily compatible, which is preferable.

(Antistatic agent)
The acrylic pressure-sensitive adhesive of this specification can contain an antistatic agent within a range that does not impair the effects of the present invention. When the release film contains an antistatic agent, it is possible to reduce the adhesion of dust and dirt when the release film is peeled off from the adhesive sheet, but there is a possibility that the adhesive force to the adherend may be impaired. When using the antistatic agent, it is important to achieve both dust resistance and adhesive strength by adjusting the type and amount of the antistatic agent.

Examples of antistatic agents include inorganic salts, ionic liquids, ionic solids, surfactants, and the like. Among these, ionic liquids are preferred. In addition, the “ionic liquid” is also referred to as a room temperature molten salt, and exhibits liquid properties at 25°C.

Inorganic salts are, for example, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate, sodium carbonate, sodium thiocyanate, and the like.

The ionic liquid is a salt of a cation and an anion, and the cation is preferably imidazolium ion, pyridinium ion, ammonium ion, or the like.

Ionic liquids containing imidazolium ions are, for example, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-butyl- 3-methylimidazolium bis(trifluoromethylsulfonyl)imide and the like.

Ionic liquids containing pyridinium ions include, for example, 1-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-butylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide, 1 -octylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methyl pyridinium bis(trifluoromethylsulfonyl)imide, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-methylpyridinium bis(perfluoroethylsulfonyl)imide, and 1-methylpyridinium bis(perfluorobutylsulfonyl)imide imide and the like.

Ionic liquids containing ammonium ions include, for example, trimethylheptylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N -methyl-N-pentylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-heptylammonium bis(trifluoromethanesulfonyl)imide, and tri-n-butylmethylammonium bistrifluoromethanesulfonimide etc.

In addition, known ionic liquids whose cations are pyrrolidinium ions, phosphonium ions, sulfonium ions, and the like can be appropriately used.

Like the ionic liquid, the ionic solid is a salt of a cation and an anion, but exhibits solid properties at 25° C. under normal pressure. Preferred cations are, for example, alkali metal ions, phosphonium ions, pyridinium ions, ammonium ions, and the like.

Ionic solids containing alkali metal ions are, for example, lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium bispentafluoroethylsulfonylimide, lithium bisheptafluoropropylsulfonylimide, lithium bisnonanefluorobutylsulfonylimide, sodium bis fluorosulfonylimide, sodium bistrifluoromethylsulfonylimide, sodium bispentafluoroethylsulfonylimide, sodium bisheptafluoropropylsulfonylimide, sodium bisnonanefluorobutylsulfonylimide, potassium bisfluorosulfonylimide, potassium bistrifluoromethylsulfonylimide, potassium bis pentafluoroethylsulfonylimide, potassium bisheptafluoropropylsulfonylimide, potassium bisnonanefluorobutylsulfonylimide and the like.

Ionic solids containing phosphonium ions are, for example, tetrabutylphosphonium bisfluorosulfonylimide, tetrabutylphosphonium bistrifluoromethylsulfonylimide, tetrabutylphosphonium bispentafluoroethylsulfonylimide, tetrabutylphosphonium bisheptafluoropropylsulfonylimide, tetrabutylphosphonium bisnonanefluorobutylsulfonylimide, tributylhexadecylphosphonium bisfluorosulfonylimide, tributylhexadecylphosphonium bistrifluoromethylsulfonylimide, tributylhexadecylphosphonium bispentafluoroethylsulfonylimide, tributylhexadecylphosphonium bisheptafluoropropylsulfonylimide, tributylhexa Decylphosphonium bisnonanefluorobutylsulfonylimide, Tetraoctylphosphonium bisfluorosulfonylimide, Tetraoctylphosphonium bistrifluoromethylsulfonylimide, Tetraoctylphosphonium bispentafluoroethylsulfonylimide, Tetraoctylphosphonium bisheptafluoropropylsulfonylimide, Tetraoctylphosphonium bis and nonanefluorobutylsulfonylimide.

Ionic solids containing pyridinium ions are, for example, 1-hexadecyl-4-methylpyridinium bisfluorosulfonylimide, 1-hexadecyl-4-methylpyridinium bistrifluoromethylsulfonylimide, 1-hexadecyl-4-methylpyridinium bispentafluoroethylsulfonyl imide, 1-hexadecyl-4-methylpyridinium bisheptafluoropropylsulfonylimide, 1-hexadecyl-4-methylpyridinium bisnonanefluorobutylsulfonylimide and the like.

Ionic solids containing ammonium ions are, for example, tributylmethylbistrifluoromethylsulfonylimide, tributylmethylbispentafluoroethylsulfonylimide, tributylmethylbisheptafluoropropylsulfonylimide, tributylmethylmbisnonanefluorobutylsulfonylimide, octyltributylbistrifluoro methylsulfonylimide, octyltributylbispentafluoroethylsulfonylimide, octyltributylbisheptafluoropropylsulfonylimide, octyltributylmubisnonanefluorobutylsulfonylimide, tetrabutylbisfluorosulfonylimide, tetrabutylbistrifluoromethylsulfonylimide, tetrabutylbis pentafluoroethylsulfonylimide, tetrabutylbisheptafluoropropylsulfonylimide, tetrabutylbisnonanefluorobutylsulfonylimide and the like.

In addition, known ionic solids whose cations are pyrrolidinium ions, imidazolium ions, sulfonium ions, and the like can be appropriately used.

Surfactants can be classified into nonionic, anionic, cationic, and amphoteric types.

Nonionic surfactants include, for example, glycerin fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, fatty acid diethanolamides, polyether ester amides. type, ethylene oxide-epichlorohydrin type, and polyether ester type.
Anionic surfactants (excluding ionic liquids and ionic solids) include, for example, alkylsulfonates, alkylbenzenesulfonates, alkylphosphates, polystyrenesulfonate types, and the like.
Cationic surfactants include, for example, tetraalkylammonium salts, trialkylbenzylammonium salts, quaternary ammonium base-containing acrylate polymer types, and the like.
Amphoteric surfactants include, for example, alkylbetaines and alkylimidazolium betaines, amino acid-type amphoteric surfactants such as higher alkylaminopropionates, betaine-type amphoteric surfactants such as higher alkyldimethylbetaines, and higher alkyldihydroxyethylbetaines. etc.

Antistatic agents distinguish between being liquid or solid at 25°C.
An antistatic agent that is liquid at 25° C. is more likely to migrate to the interface between the adhesive layer and the adherend than a solid, so that better antistatic properties can be obtained.

Also, an antistatic agent that is solid at 25° C. is more likely to partially exist as islands having a sea-island structure in the adhesive layer compared to a liquid. Since this improves the relaxation property of the adhesive layer, it is easy to obtain good flexibility.

Among these, the antistatic agent is preferably 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide or tetrabutylphosphonium bis(trifluoromethanesulfonylimide).

When an antistatic agent is used, the acrylic pressure-sensitive adhesive layer preferably has a surface resistance value of 1×10 ⁵ Ω/□ or more and 1×10 ¹⁰ Ω/□ or less in an atmosphere of 23° C.-50% RH. By blending an appropriate amount of an antistatic agent, it is possible to achieve a high level of both dust resistance, adhesive strength, and distortion suitability.

The content of the antistatic agent for expressing the surface resistance value is 0.05 to 1 mass with respect to 100 parts by mass of the acrylic copolymer (A), although it depends on the structure of the antistatic agent. parts, more preferably 0.1 to 0.8 parts by mass, even more preferably 0.1 to 0.5 parts by mass.

(organosilane compound)
The acrylic pressure-sensitive adhesive of the present invention can further contain an organic silane compound. Organosilane compounds include, for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxy Alkoxysilane compounds having a (meth)acryloxy group such as propyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane; vinyltrimethoxysilane, vinyltriethoxy Alkoxysilane compounds having a vinyl group such as silane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3 -aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)- 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-phenyl-3-amino Alkoxysilane compounds having an amino group such as propyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyl Alkoxysilane compounds having a mercapto group such as methyldiethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyl Alkoxysilane compounds having an epoxy group such as tributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; tetraalkoxysilane compounds such as methoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane; 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3 -trimethoxysilylpropyl)isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, hexamethyldisilazane, and silicone resins having alkoxysilyl groups in the molecule.

The organic silane compound is preferably contained in an amount of 0.01 to 2 parts by mass, more preferably 0.05 to 1 part by mass, based on 100 parts by mass of the acrylic copolymer (A). By containing 0.01 to 2 parts by mass of the organic silane compound, it becomes easier to form a pressure-sensitive adhesive layer with excellent strain aptitude.

The pressure-sensitive adhesive sheet of the present invention may contain various resins, oils, softeners, dyes, pigments, antioxidants, ultraviolet absorbers, weather stabilizers, plasticizers, fillers, as optional components as long as the problems can be solved. Antiaging agents, antistatic agents, and the like can be contained.

<Antistatic release film>
The antistatic treated film has a release agent layer and an antistatic layer on one or both sides of the substrate.
The layer configuration is not particularly limited, but when it is "release layer/antistatic layer/base material" from the side in contact with the adhesive layer, the adhesive sheet can be excellent in dust resistance. In the case of the "preventive layer", it is preferable because the pressure-sensitive adhesive sheet can have excellent anti-displacement properties.
In some cases, it may be "release layer/antistatic layer/substrate/antistatic layer" or the like.
Further, other layers may be provided between each layer as long as the effects of the present invention are not impaired.

(Base material)
The base material is not particularly limited, but a transparent plastic base material can be preferably used. Materials for the transparent plastic substrate include, for example, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose, polysulfone, polyarylate, Examples include plastic materials such as polycycloolefin. The plastic materials can be used singly or in combination of two or more.

Among the transparent plastic substrates mentioned above, transparent plastic substrates with excellent heat resistance, i.e., transparent plastic substrates whose deformation is suppressed or prevented under severe conditions such as high temperature, high temperature and high humidity, are preferred. It can be used preferably. A PET or PEN film or sheet is particularly suitable as the transparent plastic substrate.

The thickness of the transparent plastic substrate is not particularly limited, and is preferably 10 to 200 μm, more preferably 25 to 150 μm.

(Release agent layer)
The release agent layer is formed from a release agent. Release agents generally include silicone-based, fluorine-based, olefin-based, alkyd-based, long-chain alkyl-based, and the like. In the present invention, a silicone-based release agent is used in order to provide a wide range of peel strength.
The release agent of the present invention has a linear silicone as a main component and a branched silicone content of 1% by mass or less.

The silicone-based release agent contains silicone having a siloxane bond in its main chain. As the silicone, for example, a type having three organic substituents bonded to silicon and one oxygen atom (M unit), and a type having two organic substituents bonded to silicon and two oxygen atoms (D unit ), a type having one organic substituent bonded to silicon and three oxygen atoms (T unit), and a type having no organic substituent bonded to silicon and having four oxygen atoms (Q unit). It is possible to obtain various silicones with different peeling performances, and the magnitude of the peeling strength can be controlled by the ratio of these. In most cases, it is possible to make adjustments to make peeling easier with straight-chain silicones composed of M and D units, and to make peeling harder with branched silicones containing T and Q units in the structure of straight-chain silicones. .

As the linear silicone, a composition containing D units as a main component and appropriately containing M units for molecular weight adjustment is preferred. The organic substituent represents a hydrogen atom, a hydroxyl group, or an alkyl group, preferably an alkyl group, specifically a methyl group or a phenyl group, from the viewpoint of being easily soluble in an organic solvent.

Since linear silicone imparts various resistances, it can have a crosslinked structure. The straight-chain silicone preferably has two or more vinyl groups at its terminals and/or side chains as cross-linking points. The cross-linking agent includes hydrogen-modified silicone and the like, and it is necessary to have two or more SiH groups in one molecule.
It is preferable to include 0.1 to 20 parts by mass of hydrogen-modified silicone with respect to 100 parts by mass of linear silicone.

The branched silicone preferably has T units and/or Q units, and preferably contains 70% by mass or more of T units and/or Q units in 100% by mass of the branched silicone. Branched silicones may have M units, D units in addition to T units and/or Q units.

The release agent layer is formed from a release agent. The release agent according to the present invention contains straight-chain silicone and branched silicone in a ratio of straight-chain silicone:branched silicone=100:0 to 99:1 (mass ratio). By containing the branched silicone in an amount of 1% by mass or less with respect to the total mass of the release agent (straight-chain silicone, hydrogen-modified silicone and branched silicone), dust resistance and anti-displacement properties are improved. The proportion of branched silicone is more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less.

The total content of linear silicone, hydrogen-modified silicone and branched silicone is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, based on 100% by mass of the total mass of the release agent. , more preferably 90 to 100% by mass.

Methods for synthesizing the silicone-based release agent include addition reaction, peroxide condensation reaction, and ultraviolet cross-linking reaction, and it is preferably formed by addition reaction. The addition reaction is the cross-linking of the vinyl groups contained in the linear silicone and the SiH groups contained in the hydrogen-modified silicone.

When synthesizing the release agent by an addition reaction, it contains a catalyst. The catalyst is not particularly limited, but platinum-based catalysts are preferable, and chloroplatinic acid such as chloroplatinic acid and chloroplatinic acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, or chloroplatinic acid Complexes with various olefins and the like are more preferable.
The amount of the catalyst added is preferably 0.01 to 10% by mass, more preferably 0.2 to 2% by mass, based on 100% by mass of the total mass of the release agent.

In addition to the straight-chain silicone and the branched silicone, the release agent can contain any appropriate other component other than the catalyst within a range that does not impair the effects of the present invention. Examples thereof include reaction inhibitors, inorganic fillers, organic fillers, colorants (dyes, pigments, etc.), plasticizers, ultraviolet absorbers, antioxidants, and the like.

The release agent layer is preferably formed by coating a release agent composition on a release substrate.

The release agent can contain a solvent when applied to form the release agent layer. Examples of solvents include, but are not limited to, hydrocarbon solvents such as normal hexane, cyclohexane, and normal heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and organic solvents such as alcohol solvents such as methanol, ethanol and butanol.

As a coating method for the release agent, there are a micro gravure coater, a gravure coater, and the like.
The release agent is applied so that the solid mass is about 0.1 to 2.0 g/m ² , preferably 0.5 to 1.2 g/m ² , and cured to form a release agent layer.

As the curing method, heat curing is preferable in order to promote the addition reaction. Although the curing temperature is not particularly limited, it is preferably 80°C to 130°C. When the temperature is 80° C. or higher, long-time heating is not required for sufficient curing, and superior productivity can be obtained. Moreover, when the temperature is less than 130° C., it is possible to reduce the generation of wrinkles due to heat in the base material or the release base material.

The thickness of the release agent layer is not particularly limited, but is preferably 0.1 to 2 μm, more preferably 0.5 to 1.2 μm. If the thickness is 0.1 μm or more, the peeling performance can be fully exhibited, and if it is 2 μm or less, the winding misalignment due to the release agent layer is less likely to occur.

(Antistatic layer)
Forming an antistatic layer on the release film in the present invention is an essential condition. By forming an antistatic layer on the release film, it is possible to suppress the contamination of dust and dirt during processing such as peeling and lamination in the lamination process.

The antistatic layer can be formed from an antistatic agent containing an antistatic component. A known material can be used as the antistatic agent. Examples of antistatic components include, but are not limited to, conductive polymers. A water-soluble or water-dispersible conductive polymer is preferably used as the conductive polymer component. By using a conductive polymer, it is possible to satisfy the release antistatic property based on the antistatic layer. In addition, the conductive polymer is "water-soluble" or "water-dispersible", but can be fixed in the antistatic layer by using a cross-linking agent (for example, a melamine-based or isocyanate-based cross-linking agent) described later. Water resistance can be improved. By using the water-soluble conductive polymer or water-dispersible conductive polymer, the surface resistance of the antistatic layer can be kept low, thereby improving dust resistance.

Examples of water-soluble conductive polymers that can be used without particular limitation include polyaniline sulfonic acid, poly(isothianaphthenediyl-sulfonate) compounds, and quaternary ammonium salt-containing (meth)acrylic acid ester polymers.
Moreover, the water-dispersible conductive polymer is not particularly limited and can be used. Examples thereof include polythiophenes doped with polyanions and polyaniline. Among these, polyaniline sulfonic acid is preferably used as the water-soluble conductive polymer, and polythiophenes doped with polyanions are preferably used as the water-dispersible conductive polymer.

Examples of polythiophenes that can be used as water-dispersible conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), Poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly( 3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly( 3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly (3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4- dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3 ,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-di dodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butenedioxythiophene), poly(3-methyl-4-methoxy thiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene, poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3 -methyl-4-carboxybutylthiophene).These may be used alone or in combination of two or more.Among them, from the viewpoint of conductivity, poly(3,4-ethylene dioxythiophene) (PEDOT) is preferred.

Polythiophenes preferably have a degree of polymerization of 2 to 1,000, more preferably 5 to 100. When the degree of polymerization is in the range of 2 to 1000, the conductivity is excellent and the dust resistance is improved.

Polyanions are polymers of structural units having anionic groups and function as dopants for polythiophenes. Examples of polyanions include polystyrenesulfonic acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyacrylsulfonic acid, polymethacrylsulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, poly Sulfoethyl methacrylate, poly(4-sulfobutyl methacrylate), polymethallyloxybenzenesulfonic acid, polyvinylcarboxylic acid, polystyrenecarboxylic acid, polyallylcarboxylic acid, polyacryliccarboxylic acid, polymethacryliccarboxylic acid, poly(2-acrylamide- 2-methylpropanecarboxylic acid), polyisoprenecarboxylic acid, polyacrylic acid, polysulfonated phenylacetylene, and the like. Among them, polystyrene sulfonic acid (PSS) is preferable from the viewpoint of improving the conductivity and dispersibility of polythiophenes. These may be homopolymers or copolymers of two or more.

Polyanions preferably have a mass average molecular weight (Mw) of 1,000 to 1,000,000, more preferably 2,000 to 500,000. If it is in the range of 1,000 to 1,000,000, it is preferable because it is excellent in doping and dispersibility in polythiophenes.

As an antistatic layer, for example, when poly(3,4-ethylenedioxythiophene) (PEDOT) as polythiophenes and polystyrene sulfonic acid (PSS) as polyanions capable of doping with the polythiophenes are used. In addition, PEDOT and PSS interact and exist at close range, so that PSS deprives PEDOT of electrons, which allows the antistatic layer to exhibit conductivity and improve dust resistance.

Commercial products of polythiophenes doped with polyanions include, for example, poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid (PEDOT/PSS) manufactured by Bayer under the trade name "BytronP" and Shin-Etsu Polymer Co., Ltd. "Seprugida" (trade name) manufactured by Soken Kagaku Co., Ltd., and "Verazol" (trade name) manufactured by Soken Kagaku Co., Ltd. are exemplified.

The polyaniline sulfonic acid that can be used as the water-soluble conductive polymer component preferably has a polystyrene equivalent weight average molecular weight (Mw) of 5×10 ⁵ or less, more preferably 3×10 ⁵ or less. Also, the weight average molecular weight of these conductive polymers is preferably 1×10 ³ or more, more preferably 5×10 ³ or more.

Commercially available products of polyaniline sulfonic acid include "aquaPASS" (trade name) manufactured by Mitsubishi Rayon Co., Ltd., and the like.

The antistatic layer can be formed from an antistatic agent containing an antistatic component such as a conductive polymer in a known resin. The known resin is not particularly limited, but preferably contains a polyester resin as a binder. A known resin material containing polyester as a main component can be used as the polyester resin.
As the cross-linking agent, a melamine-based, isocyanate-based, epoxy-based, or other cross-linking agent that is used for cross-linking general resins can be appropriately selected and used.

The amount of the conductive polymer used is preferably 10 to 200 parts by mass, more preferably 25 to 150 parts by mass, still more preferably 40 to 120 parts by mass, based on 100 parts by mass of the binder. When the amount of the conductive polymer used is 10 to 200 parts by mass, more sufficient dust resistance can be ensured.

As a method for forming an antistatic layer, a method of coating and drying (or curing) a coating material for forming an antistatic layer (antistatic agent composition) on one or both sides of the base film can be adopted. Preparation of the coating material A water-soluble conductive polymer or a water-dispersible conductive polymer can be used as the conductive polymer component, or a polyester resin can be contained as a binder, and the conductive polymer dissolved or dispersed in water is preferably used. obtain. A conductive polymer aqueous solution or water dispersion can be prepared, for example, by dissolving/dispersing a conductive polymer having a hydrophilic functional group in water. Examples of hydrophilic functional groups include sulfo group, amino group, amide group, imino group, hydroxyl group, mercapto group, hydrazino group, carboxyl group, quaternary ammonium group, sulfate group, and phosphate group. The hydrophilic functional group may form a salt.

The thickness of the antistatic layer is preferably 3-500 nm, more preferably 3-100 nm, still more preferably 3-50 nm. If the antistatic layer has a thickness of 3 to 500 nm, it is possible to form a pressure-sensitive adhesive sheet with excellent dust resistance.

The release film has a surface resistance value (Ω/□) measured on the release agent surface of 1×10 ¹⁰ Ω/□ or less, preferably 1×10 ⁹ Ω/□ or less, more preferably 1×10 Ω/□ or less. It is 1×10 ⁸ Ω/□ or less, more preferably 1×10 ⁷ Ω/□ or less. A release film exhibiting a surface resistance value of 1×10 ¹⁰ Ω/□ or less is suitably used as a film used in the process of processing or conveying articles that should not be contaminated with dust due to static electricity.
Although the lower limit of the surface resistance value is not particularly limited, it is preferably 1×10 ⁵ Ω/□ or more.
The surface resistance value can be calculated from the surface resistance value measured in an atmosphere of 23° C.-50% RH using a commercially available electrical resistance measuring device.

Other treatments on the release film may include appropriate surface treatments such as physical treatments such as corona discharge treatment and plasma treatment, and chemical treatments such as undercoating treatment.

<Production of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention can be produced according to a conventional pressure-sensitive adhesive sheet production method. For example, an acrylic pressure-sensitive adhesive, which is a mixture of an acrylic copolymer (A) and a curing agent, is directly applied to the release layer side of the release film so that the thickness after drying becomes a predetermined thickness. A method of forming a pressure-sensitive adhesive layer and attaching another release film, or coating the pressure-sensitive adhesive on the release layer side of two release films so that the thickness after drying becomes a predetermined thickness, 2 It can be produced by a method of forming two pressure-sensitive adhesive layers and then attaching each pressure-sensitive adhesive layer. Any of the release films used at this time has a surface resistance value of 1×10 ¹¹ Ω/□ or less in a 23° C.-50% RH atmosphere of the release agent layer, and the main component of the release agent layer is linear silicone. and a branched silicone content of 1% by mass or less. Especially, it is preferable that both release films are the antistatic films.

The lower limit of the film thickness of the pressure-sensitive adhesive layer is 25 μm or more, and the upper limit is not particularly limited. When the thickness of the pressure-sensitive adhesive layer is 25 to 500 μm, it is preferable because sufficient cohesive strength can be easily obtained, and both distortion suitability and adhesive strength can be highly compatible.

When applying the adhesive, a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater can be used.

The adhesive sheet may be in the form of an adhesive tape wound into a roll by cutting it into an appropriate width and winding it into a roll.

"Laminate"
The laminate includes an adherend and an acrylic pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive sheet of the present invention.
Specifically, for example, the antistatic treatment release film is peeled off from the adhesive sheet for a flexible display of the present invention, the film substrate (cover panel), the touch sensor (transparent conductive layer, refractive index adjusting layer, protective layer is the outermost layer ), a laminate can be formed by attaching an adhesive layer to an adherend such as a reinforcing metal plate, a polarizing plate, or an optical element.

FIG. 2 shows an example of a schematic cross-sectional view partially showing a laminate, which is an example of use of the pressure-sensitive adhesive sheet of the present invention. In FIG. 2, 3 is a film substrate, 1 is an adhesive layer 1, and 4 is a polarizing plate.

In the laminate shown in FIG. 2, the film substrate is attached to the polarizing plate via the adhesive layer comprising the adhesive of the present invention. Thus, the pressure-sensitive adhesive sheet of the present invention can be used in a form in which an acrylic pressure-sensitive adhesive layer formed from an acrylic pressure-sensitive adhesive is attached to a film substrate (cover panel) and a polarizing plate.

The film substrate (cover panel) is not particularly limited, but a transparent plastic substrate or an ultra-thin glass (UTG) substrate can be preferably used. Examples of materials for the transparent plastic substrate include acrylic resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polymethyl methacrylate (PMMA), and plastic materials such as polycarbonate, polycycloolefin, and polyimide. be done. The plastic material and glass material can be used singly or in combination of two or more.

As the film substrate (cover panel), in the case of a transparent plastic substrate as described above, a transparent plastic substrate with excellent heat resistance, i.e., a transparent plastic substrate that does not deform under severe conditions such as high temperature and high humidity. A transparent plastic substrate that is inhibited or prevented can be suitably used. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycycloolefin, and polyimide are particularly suitable as transparent plastic substrates.

The thickness of the film substrate (cover panel) is not particularly limited, and is preferably 100 to 2000 μm, more preferably 200 to 1000 μm.

"Flexible Display"
A flexible display includes an optical element and an acrylic pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive sheet of the present invention.
The flexible display is flexible and has resistance to damage even when bent or twisted, and the optical element is not particularly limited, and examples thereof include a liquid crystal element and an organic EL element.

The optical element is, for example, a deformable image display portion such as an organic electroluminescence element layer (hereinafter referred to as an OLED layer) or a liquid crystal element layer, and is a member capable of some strain deformation from a planar state such as bending or bending. Said deformation may be temporary or permanent.
The OLED layer includes, for example, a structure in which an anode, a hole injection/transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a cathode, a sealing material, and an inorganic barrier layer are sequentially laminated on a film substrate. Known materials can be used for various materials, layer structures, and manufacturing methods that constitute the OLED layers.

A flexible display has an adhesive layer formed using the adhesive sheet of the present invention.
Specifically, for example, the antistatic treatment release film is peeled off from the pressure-sensitive adhesive sheet for flexible displays of the present invention, and the exposed acrylic pressure-sensitive adhesive layer is adhered to an adherend such as a film substrate or a polarizing plate. A laminate can be formed and attached to an optical element via another pressure-sensitive adhesive layer to form a flexible display.

FIG. 3 shows an example of a schematic cross-sectional view partially showing a display, which is an example of use of the pressure-sensitive adhesive sheet of the present invention. In FIG. 3, 3 is a film substrate (cover panel), 1 is an adhesive layer 1, 4 is a polarizing plate, 5 is an adhesive layer 2, 6 is a barrier layer such as silicon nitride, 7 is an organic EL layer, and 8 is a A support such as polyimide, 9 is an organic EL cell. Note that the configuration of the display is not limited to that shown in FIG.

In the display shown in FIG. 3, the film substrate (cover panel) is attached to the polarizing plate via the adhesive sheet containing the adhesive layer 1 formed by the adhesive sheet of the present invention, and the polarizing plate adhesive It can be attached to an organic EL cell via an adhesive layer (adhesive layer 2) to form a flexible display.

Moreover, it can also be used to form the adhesive layer for a polarizing plate (adhesive layer 2) shown in FIG. The treated release film is peeled off, and the exposed acrylic pressure-sensitive adhesive layer is attached to the optical element to form a laminate. It can be a flexible display.
That is, for example, in FIG. 3, the adhesive of the present invention can be used for both the adhesive layer 1 and the adhesive layer 2. FIG.

Applications of the display are not particularly limited, but include organic EL televisions, organic EL smartphones, organic EL tablets, organic EL smart watches, and the like.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these. In the examples, unless otherwise specified, "part" indicates "mass part" and "%" indicates "% by mass."
and "RH" means relative humidity. In addition, the compounding amounts in the table are parts by mass. still,
A blank column in the table indicates that it was not blended.
The glass transition temperature and mass average molecular weight of the acrylic copolymer and the acrylic pressure-sensitive adhesive layer, and the method for measuring the surface resistance of the antistatic release film are as follows.

<Calculation of Glass Transition Temperature of Acrylic Copolymer and Acrylic Pressure-Sensitive Adhesive Layer>
The glass transition temperature (Tg) of the acrylic pressure-sensitive adhesive layer was measured by a robot DSC (differential scanning calorimeter, "RDC220" manufactured by Seiko Instruments Inc.). About 2 mg of the sample is put in an aluminum pan, weighed and set in a differential scanning calorimeter, and the same type of aluminum pan without a sample is used as a reference, and after holding at a temperature of 100 ° C. for 5 minutes, liquid nitrogen is used to - Quenched to 120°C. Thereafter, the temperature was raised at a rate of temperature increase of 5° C./min, and the glass transition temperature (Tg, unit:° C.) was determined from the obtained DSC chart.

<Measurement of mass average molecular weight of acrylic copolymer>
The mass average molecular weight (Mw) is measured using GPC "LC-GPC system" manufactured by Shimadzu Corporation, and the mass average molecular weight (Mw) can be determined by conversion using polystyrene with a known molecular weight as a standard substance.
Apparatus name: LC-GPC system "Prominence" manufactured by Shimadzu Corporation
Column: 4 GMHXL manufactured by Tosoh Corporation and 1 HXL-H manufactured by Tosoh Corporation were connected.
Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 ml/min Column temperature: 40°C

<Measurement of surface resistance value of acrylic pressure-sensitive adhesive layer and antistatic treatment release film>
The surface resistance of the surface of the acrylic pressure-sensitive adhesive layer and the surface of the release agent layer of the antistatic release film was measured using Hiresta-UX MCP-HT800 (manufactured by Nitto Seiko Analytic Co., Ltd.).

<Production example of acrylic copolymer>
(Acrylic copolymer (A-1))
100 parts of ethyl acetate and 80 parts of 2-ethylhexyl acrylate (2EHA) were placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube (hereinafter simply referred to as the "reaction vessel"). part, butyl acrylate (BA) 15 parts, methyl acrylate (MA) 3 parts, acrylic acid (AA) 1 part, 2-hydroxyethyl acrylate (HEA) 1 part, 2,2'-azo as an initiator 0.1 part of bisisobutyronitrile (hereinafter simply referred to as "AIBN") was charged, and the atmosphere in the reaction vessel was replaced with nitrogen gas. After that, the reaction was started by heating to 65° C. while stirring in a nitrogen atmosphere. After that, the reaction solution was reacted at 65° C. for 4 hours. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain an acrylic copolymer (A-1) solution having a non-volatile content of 30%. The mass average molecular weight of the obtained acrylic copolymer (A-1) was 800,000.

(Acrylic copolymer (A-2 to 6)
The acrylic copolymer (
Acrylic copolymers (A-2 to A-6) were produced in the same manner as in A-1).

Table 1 shows the weight average molecular weights (Mw) of the obtained adhesives (A-1, 2 to 6).

Abbreviations in the table are as follows.
(Monomer (a-1))
MA: methyl acrylate (1 carbon number)
(Monomer (a-2))
IBXA: isobornyl acrylate (monomer (a-3)
2EHA: 2-ethylhexyl acrylate (8 carbon atoms)
(Monomer (a-4)
AA: acrylic acid HEA: 2-hydroxyethyl acrylate (monomer (a-5)
BA: butyl acrylate (4 carbon atoms)

<Production of antistatic release film>
(Antistatic treatment release film (B-1))
100 parts of Vylonal MD-1480 (manufactured by Toyobo Co., Ltd.) as a main binder, 70 parts of Aquapass (manufactured by Mitsubishi Chemical Corporation) as a conductive polymer, 10 parts of diisopropylamine-blocked hexamethylene diisocyanate-nurate as a cross-linking agent, and as a lubricant 20 parts of oleic acid amide was diluted with water and thoroughly mixed with stirring to prepare an antistatic agent.
The antistatic agent is coated on a polyethylene terephthalate (PET) film having a thickness of 50 μm with a gravure coating machine so that the thickness after drying is 25 nm, and dried at 140 ° C. for 2 minutes to form an antistatic agent layer. formed.

Next, as the main binder, 100 parts of an addition reaction type silicone having a vinyl group content of 5 mol %, 1 part of a platinum-based catalyst, and 200 parts of toluene are used with respect to 100 parts of the methyl group content in the silicone. A release agent was prepared by blending and stirring and thoroughly mixing as follows.
The addition-reactive silicone contained linear silicone having two or more vinyl groups as crosslinkable reactive groups and hydrogen-modified silicone, and the content of branched silicone was 0% by mass.
The prepared release agent is coated on the antistatic layer with a gravure coating machine so that the film thickness after drying is 1 μm, and dried at 120° C. for 2 minutes to form a release agent layer. An antistatic release film (B-1) having a layer structure of /antistatic layer/releasing agent layer was obtained.

(Antistatic treatment release film (B-2, 3), (B'-1))
A release agent was formed in the same manner as the antistatic treatment release film (B-1) except that the release agent was changed as shown in Table 2, and the layer structure of base material / antistatic layer / release agent layer was formed. Antistatic release films (B-2, 3) and (B'-1) were obtained.
The release agent contains linear silicone having two or more vinyl groups as crosslinkable reactive groups, hydrogen-modified silicone, and branched silicone at the content shown in Table 2 depending on the production conditions. got something to do

(Antistatic treatment release film (B-4))
An antistatic agent and a release agent were produced in the same manner as in the production of the antistatic release film (B-1).
An antistatic agent is applied to a polyethylene terephthalate (PET) film having a thickness of 50 μm with a gravure coating machine so that the thickness after drying is 25 nm, and dried at 140 ° C. for 2 minutes to form an antistatic agent layer. formed.
Subsequently, a release agent is applied to the opposite side of the substrate from the antistatic agent layer using a gravure coating machine so that the film thickness after drying is 1 μm, and dried at 120° C. for 2 minutes to form a release agent layer. was formed to obtain an antistatic release film (B-4) having a layer structure of antistatic layer/substrate/release agent layer.
In the release agent, the addition reaction type silicone contained linear silicone having two or more vinyl groups as crosslinkable reactive groups and hydrogen-modified silicone, and the content of branched silicone was 0% by mass.

(Peeling film (B'-2))
A release agent was produced in the same manner as in the production of the antistatic release film (B-1).
The release agent is coated on a polyethylene terephthalate (PET) film with a thickness of 50 μm using a gravure coating machine so that the film thickness after drying is 1 μm, and dried at 120° C. for 2 minutes to form a release agent layer. Then, a release film (B'-2) having a layer structure of substrate/release agent layer was obtained.

Table 2 shows the compositions, surface resistance values, and layer structures of the release agents of the antistatic release films (B-2 to 4), (B'-1), and release film (B'-2).

(Example 1)
<Preparation of adhesive>
Per 100 parts of acrylic copolymer (A-1) nonvolatile matter, 0.1 part of tolylene diisocyanate-trimethylolpropane adduct as a curing agent, 3-glycidoxypropyltrimethoxysilane (S -1) 0.2 part, and ethyl acetate were added so that the non-volatile content was 20%, and stirred to obtain an acrylic pressure-sensitive adhesive.

<Production of adhesive sheet>
The obtained acrylic pressure-sensitive adhesive was coated on the release agent layer of the antistatic treatment release film (B-1) (release film 1) so that the thickness after drying was 75 μm, and was applied at 110° C. for 3 hours. A pressure-sensitive adhesive layer was formed by drying for minutes. Next, the release agent layer of the antistatic treatment release film (B-2) (release film 2) is attached to this adhesive layer, and aged at a temperature of 25 ° C. and a relative humidity of 55% for 1 week. A pressure-sensitive adhesive sheet having a structure of “treated release film (B-1)/adhesive layer/antistatic treated release film (B-2)” was obtained.

(Examples 2 to 13, Comparative Examples 1 and 2)
As shown in Tables 3 and 4, an acrylic copolymer was prepared in the same manner as in Example 1 except that the types and blending amounts (parts by mass) of the acrylic copolymer, curing agent, antistatic agent, and organic silane compound were changed. Got the adhesive. Then, using the release films shown in Tables 3 and 4, pressure-sensitive adhesive sheets were produced in the same manner as in Example 1.

<<Evaluation of Adhesive Sheet>>
The obtained pressure-sensitive adhesive sheet was evaluated for dust resistance, anti-displacement, distortion aptitude, and adhesive strength. Tables 3 and 4 show the results.
In the production of the laminate, if one side of the release film to be peeled off from the adhesive sheet is an antistatic release film, peel off the antistatic release film and attach the exposed acrylic adhesive layer to the adherend. A laminate was produced and evaluated. When antistatic release films were used on both sides, the antistatic release film (release film 1) having a lighter release force and easier to peel off was first peeled off in order to produce a laminate and evaluated.

<Dust resistance>
In a clean room (class 1000) environment, the antistatic release film was peeled off from the produced pressure-sensitive adhesive sheet, and the adhesive sheet was laminated to a base film (cover panel) to form a laminate. The dust resistance of the obtained laminate was measured by measuring an area of 25 cm width×100 cm length using a defect inspection machine.
[Evaluation criteria]
⊚: Excellent, no foreign matter such as dust or dirt is observed.
◯: Good; one foreign matter such as dust or dirt is observed.
Δ: Two or three foreign substances such as dust and dirt are observed, and there is no practical problem.
x: Four or more foreign substances such as dust and dirt are observed, which is problematic in practice.

<Winding misalignment resistance>
A 4 cm square sample was prepared by cutting the obtained pressure-sensitive adhesive sheet, and a load of 2 kg/cm ² was applied using a blocking tester, and the sample was allowed to stand at 40° C. for 24 hours. After that, the sample was taken out from the tester and allowed to stand at 23° C. for 1 hour, and the degree of displacement between the antistatic treated film and the pressure-sensitive adhesive layer after curing was visually evaluated. Evaluation criteria are as follows.
[Evaluation criteria]
⊚: Excellent, no winding misalignment at all.
◯: Good, with winding misalignment of 0.1 mm or less.
Δ: Winding misalignment occurred within a range of more than 0.1 mm and 0.3 mm or more, practically no problem.
x: There is a problem in practical use that the winding misalignment exceeds 0.3 mm.

<Strain suitability>
The antistatic release film was peeled off from the adhesive layer of the obtained adhesive sheet, and the exposed adhesive layer was laminated on a polyimide film. Then, the other antistatic release film was peeled off from the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer was laminated to an easily adhesive PET film. The laminate was placed in an autoclave and held at 50°C for 20 minutes. Next, the laminate was taken out and allowed to stand at 23° C.-50% RH for 30 minutes. got a body
Next, the laminate for testing was twisted left and right in an atmosphere of 25° C. and 50% RH with a planar body no-load twist tester (manufactured by Yuasa System Equipment Co., Ltd.), and then the time until it returned to the state before twisting was 1. 200,000 cycles were repeated as cycles. The test was conducted with N=5, and the appearance after the test was evaluated. The evaluation criteria are as follows.
[Evaluation criteria]
⊚: Excellent with no bubble generation, no floating or peeling observed in all 5 times.
Good: Bubbles are generated only once, and slight floating and peeling are observed.
Δ: Bubble generation, floating, and peeling are slightly observed at a frequency of 2 or 3 times, and there is no practical problem.
x: Slight bubble generation, floating, or peeling observed at a frequency of 4 or more times, or significant bubble generation, lifting, or peeling observed even once, presenting a practical problem.

<Adhesive strength>
The antistatic release film was peeled off from the adhesive layer of the resulting adhesive sheet, and the exposed adhesive layer was laminated to an easily adhesive PET film. Then, the other antistatic release film was peeled off from the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer was laminated to the polyimide film. The readily adhesive PET film/adhesive layer/polyimide thus obtained was prepared in a size of 25 mm in width and 100 mm in length, and used as a measurement sample. Then, in an atmosphere of 23° C.-50% RH, a 2-kg roll was reciprocated once to press-bond. After that, it was left for 24 hours under the condition of 23°C. Using a tensile tester, the adhesive strength between the adhesive layer and the polyimide was measured under the conditions of a 23° C. environment, a peel speed of 300 mm/min, and a peel angle of 180°. Evaluation criteria are as follows.
[Evaluation criteria]
A: 20 N/25 mm or more, excellent.
◯: 15 N/25 mm or more and less than 20 N/25 mm, good.
Δ: 10 N/25 mm or more and less than 15 N/25 mm, practically no problem.
x: less than 10 N/25 mm, practically problematic.

Abbreviations in the table are as follows.
<Curing agent>
NCO: tolylene diisocyanate-trimethylolpropane adduct <antistatic agent>
E-1: 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide <organosilane compound>
S-1: 3-glycidoxypropyltrimethoxysilane

From the results in Tables 3 and 4, it was confirmed that the pressure-sensitive adhesive sheets of Examples were excellent in all rollable flexibility properties in addition to anti-displacement properties and antistatic properties. As a result, the laminate and the display using the pressure-sensitive adhesive sheet of the present invention are excellent in winding misalignment resistance, antistatic property, and rollable flexibility. Furthermore, the display of the present invention was excellent in visibility as well as convenience. On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 could not satisfy all of the above characteristics.

1 adhesive layer 1
2 Antistatic treatment release film 3 Film substrate (cover panel)
4 polarizing plate 5 adhesive layer 2
6 barrier layer 7 organic EL layer 8 support 9 organic EL cell

Claims (8)

An acrylic adhesive layer is provided on the release agent layer of the antistatic release film,
The release agent layer has a surface resistance value of 1×10 ¹¹ Ω/□ or less in an atmosphere of 23° C.-50% RH,
The release agent layer has a linear silicone as a main component and a branched silicone content of 1% by mass or less,
The acrylic pressure-sensitive adhesive layer has a glass transition temperature of −55° C. or lower.
Adhesive sheet for flexible displays. The pressure-sensitive adhesive sheet for a flexible display according to claim 1, wherein the acrylic pressure-sensitive adhesive layer has a thickness of 50 µm or more. The acrylic pressure-sensitive adhesive layer contains an acrylic copolymer (A),
The pressure-sensitive adhesive sheet for a flexible display according to claim 1 or 2, wherein the acrylic copolymer (A) contains an acrylic copolymer having a mass average molecular weight of 800,000 or more. The acrylic copolymer (A) is
A monomer containing at least one of (meth)acrylic acid alkyl ester monomer (a-1) having an alkyl group having 1 or 2 carbon atoms and (meth)acrylic acid alkyl ester monomer (a-2) having an alicyclic structure 4. The pressure-sensitive adhesive sheet for a flexible display according to claim 3, which is a copolymer of mixtures. The monomer mixture further contains a (meth)acrylic acid alkyl ester monomer (a-3) having an alkyl group having 8 to 12 carbon atoms,
5. The pressure-sensitive adhesive sheet for a flexible display according to claim 4, wherein the content of the monomer (a-3) is 80% by mass or more in 100% by mass of the monomer mixture. The acrylic pressure-sensitive adhesive layer contains an antistatic agent,
6. The pressure-sensitive adhesive sheet for a flexible display according to claim 1, wherein the acrylic pressure-sensitive adhesive layer has a surface resistance of 1×10 ¹⁰ Ω/□ or less in an atmosphere of 23° C.-50% RH. A method for producing a laminate comprising an adherend and an acrylic pressure-sensitive adhesive layer,
A method for producing a laminate, comprising a step of peeling the antistatic treatment release film from the pressure-sensitive adhesive sheet for a flexible display according to any one of claims 1 to 6, and attaching an acrylic pressure-sensitive adhesive layer to an adherend. A method for manufacturing a flexible display comprising an optical element and an acrylic pressure-sensitive adhesive layer,
A method for producing a flexible display, comprising a step of peeling the antistatic treatment release film from the adhesive sheet for a flexible display according to any one of claims 1 to 6 and attaching an acrylic adhesive layer to an optical element.

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