JP2023144908A - Adhesive sheet, laminate for constructing image display device, and image display device - Google Patents

Abstract

To provide an adhesive sheet that has excellent adhesion and transparency and also excellent antistatic performance.SOLUTION: An adhesive sheet is composed of an adhesive composition [I] that includes a (meth)acrylic polymer with hydroxy groups (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), and an antistatic agent with nitrogen or phosphorus atoms (D).SELECTED DRAWING: None

Description

The present invention relates to an adhesive sheet, a laminate for configuring an image display device, and an image display device, and more specifically, an adhesive sheet and a laminate for configuring an image display device that have excellent adhesive strength, transparency, and antistatic performance. The present invention relates to the body and image display devices.

BACKGROUND ART Image display devices such as liquid crystal displays (LCDs) and organic electroluminescent displays (OLEDs), and input devices used in combination with image display devices such as touch panels are widely used. In the manufacture of these image display devices and input devices, transparent adhesive sheets are used to bond optical components together, and transparent adhesive sheets are also used to bond image display devices and input devices together. ing.

For example, Patent Document 1 describes a method for producing a laminate for configuring an image display device having a configuration in which components for an image display device are laminated on at least one side of a transparent double-sided pressure-sensitive adhesive sheet. After laminating two image display device constituent members via the photocurable adhesive sheet, the photocurable adhesive sheet is irradiated with ultraviolet rays through the image display device constituent member to cause secondary crosslinking and hardening. A method is disclosed.

Further, Patent Document 2 describes a (meth)acrylic polymer (A), a compound (B) having a radically polymerizable functional group having a carbon-carbon double bond and a radical generating group in the molecule, and the compound (B). It is disclosed that by forming a pressure-sensitive adhesive sheet from a pressure-sensitive adhesive composition containing an initiator (C) consisting of a compound other than ), reliability and metal corrosion can be improved by improving cohesive force and not generating acid. ing.

International Publication No. 2012/32995 JP2020-76100A

However, since the adhesive sheets disclosed in Patent Documents 1 and 2 do not have antistatic properties, electric charges are generated and accumulated due to friction from the upper surface of the laminated adhesive sheet, thereby forming an image display device. There is a concern that defects may occur inside the circuit board, resulting in poor edge display. Therefore, in recent years, there has been an increasing demand for antistatic performance in order to improve such edge display defects, and pressure-sensitive adhesive sheets having antistatic performance are being sought.

Against this background, it is an object of the present invention to provide a pressure-sensitive adhesive sheet that is not only excellent in adhesive force and transparency, but also has excellent antistatic performance.

However, as a result of extensive studies in view of the above circumstances, the present inventors have found that an adhesive composition containing a specific (meth)acrylic polymer, a (meth)acrylate monomer, and a photopolymerization initiator has a further specific property. The present invention was completed based on the discovery that a pressure-sensitive adhesive sheet containing an antistatic agent not only has excellent adhesive strength and transparency, but also has excellent antistatic performance.

In addition, in a pressure-sensitive adhesive sheet, the inclusion of an antistatic agent in the pressure-sensitive adhesive composition itself is disclosed in, for example, Japanese Patent Application Laid-open No. 2018-177901. This method uses a thermal crosslinking agent such as, and is premised on thermal crosslinking, and is different from the present invention, in which crosslinking is particularly attempted by active energy rays. Although crosslinking using active energy rays has the advantage of higher productivity than thermal crosslinking, it is difficult to incorporate additives that inhibit crosslinking due to active energy rays, such as antistatic agents. However, in the present invention, we purposely added an antistatic agent, and surprisingly, by combining a specific antistatic agent and a specific (meth)acrylic polymer, crosslinking properties can be improved. It has been discovered that the adhesive has excellent antistatic performance while maintaining good adhesion and transparency without deterioration.

The present invention has the following aspects.
[1]
Adhesive composition containing a hydroxyl group-containing (meth)acrylic polymer (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), and a nitrogen or phosphorus atom-containing antistatic agent (D) An adhesive sheet formed from the product [I].
[2]
The adhesive sheet according to [1], wherein the hydroxyl group-containing (meth)acrylic polymer (A) has a hydroxyl value of 10 to 120 mgKOH/g.
[3]
The adhesive sheet according to [1] or [2], wherein the (meth)acrylate monomer (B) includes a monofunctional (meth)acrylate monomer (B1) having a benzophenone structure and one (meth)acryloyl group. .
[4]
The method according to any one of [1] to [3], wherein the (meth)acrylate monomer (B) includes a polyfunctional (meth)acrylate monomer (B2) having two or more (meth)acryloyl groups. adhesive sheet.
[5]
The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the photopolymerization initiator (C) includes a hydrogen abstraction type photopolymerization initiator (c1).
[6]
The pressure-sensitive adhesive sheet according to any one of [1] to [5], wherein the antistatic agent (D) contains an antistatic agent that does not have a polymerizable group.
[7]
The pressure-sensitive adhesive sheet according to any one of [1] to [6], wherein the pressure-sensitive adhesive composition [I] contains a silane coupling agent (E).
[8]
The content of the (meth)acrylate monomer (B) is 0.1 to 15 parts by mass based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A), [1] to [ 7].
[9]
[1] to [8], wherein the content of the antistatic agent (D) is 0.1 to 30 parts by mass based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). The adhesive sheet described in any of the above.
[10]
The adhesive sheet according to any one of [1] to [9], which has photocurability.
[11]
The adhesive sheet according to any one of [1] to [10], which is used for bonding constituent members of an image display device.
[12]
A laminate for configuring an image display device, in which two image display device component members are laminated via the adhesive sheet according to any one of [1] to [11].
[13]
A laminate for configuring an image display device, in which two image display device constituent members are laminated via a cured pressure-sensitive adhesive sheet obtained by curing the pressure-sensitive adhesive sheet according to any one of [1] to [11].
[14]
An image display device configured using the laminate for configuring an image display device according to [12] or [13].

The pressure-sensitive adhesive sheet of the present invention has not only excellent adhesive strength and transparency, but also excellent antistatic performance. Therefore, it is possible to provide a useful pressure-sensitive adhesive sheet that, for example, reduces the accumulation of electric charges caused by friction and prevents edge display defects.

The present invention will be described below based on examples of modes for carrying out the invention. However, the present invention is not limited to the embodiments described below.
In addition, in the present invention, even when referred to as a "film" it shall include a "sheet", and even when referred to as a "sheet" it shall include a "film".

In the present invention, when "X to Y" (X and Y are arbitrary numbers) means "more than or equal to X and less than or equal to Y", unless otherwise specified, and "preferably greater than It also includes the meaning of "less than".
In addition, when it is written as "more than or equal to X" (X is any number), it includes the meaning of "preferably greater than X" unless otherwise specified, and it is written as "less than or equal to Y" (where Y is any number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".
Furthermore, "X and/or Y (X, Y are arbitrary configurations)" means at least one of X and Y, and means three types: X only, Y only, and X and Y. It is something to do.

In the present invention, the term "main component" refers to a component that has a large effect on the properties of an object, and the content of this component is usually 30% by mass or more, preferably 35% by mass in the object. The content is more preferably 50% by mass or more. In addition, it is often a component that occupies the largest mass ratio in the target object, and when it accounts for 50% by mass or more, it is especially 55% by mass or more, especially 60% by mass or more, especially 70% by mass or more, In particular, it is assumed that the content is 80% by mass or more, especially 90% by mass or more (including 100% by mass).
In the present invention, "(meth)acrylic" refers to "acrylic" and "methacrylic", "(meth)acrylate" refers to "acrylate" and "methacrylate", and "(meth)acryloyl" refers to " The meaning includes ``acryloyl'' and ``methacryloyl,'' respectively.
Furthermore, the term "acrylic polymer" refers to a polymer containing a monomer unit derived from (meth)acrylate, and includes a (meth)acrylic copolymer.

<<This adhesive sheet>>
The adhesive sheet according to an example of the embodiment of the present invention (hereinafter also referred to as "the present adhesive sheet") is an adhesive sheet formed from the adhesive composition [I], and is used especially for laminating components of an image display device. Useful as an adhesive sheet.

<<Adhesive composition [I]>>
The adhesive composition [I] forming the present adhesive sheet contains a hydroxyl group-containing (meth)acrylic polymer (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), and a nitrogen atom or It is important that it contains a phosphorus atom-containing antistatic agent (D). In particular, hydroxyl group-containing (meth)acrylics are preferred because they improve the compatibility of each component constituting the pressure-sensitive adhesive composition [I] and exhibit sufficient antistatic performance while maintaining good adhesive strength and transparency. It is important to blend the polymer (A) and the nitrogen atom- or phosphorus atom-containing antistatic agent (D) in combination. Each component will be explained below.

<Hydroxy group-containing acrylic polymer (A)>
The hydroxyl group-containing (meth)acrylic polymer (A) is an acrylic polymer containing one or more hydroxyl groups in the molecule, preferably an acrylic polymer containing a structural moiety derived from the hydroxyl group-containing (meth)acrylate (a1). It is a polymer. More preferably, it is an acrylic polymer containing a structural part derived from hydroxyl group-containing (meth)acrylate (a1) and a structural part derived from alkyl (meth)acrylate (a2), and even more preferably, hydroxyl group-containing (meth)acrylate (a2). The copolymerization components constituting the system polymer (A) include a hydroxyl group-containing (meth)acrylate (a1) and an alkyl (meth)acrylate (a2), and are obtained by copolymerization.
The copolymerization component may also be one obtained by copolymerizing with other monomer components (a3) other than the hydroxyl group-containing (meth)acrylate (a1) and the alkyl (meth)acrylate (a2).

<Hydroxy group-containing (meth)acrylate (a1)>
Examples of the hydroxyl group-containing (meth)acrylate (a1) include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, Hydroxy (meth)acrylates such as 8-hydroxyoctyl (meth)acrylate, caprolactone-modified hydroxy (meth)acrylates such as caprolactone-modified 2-hydroxyethyl (meth)acrylate, diethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, etc. Oxyalkylene-modified (meth)acrylate, primary hydroxyl group-containing (meth)acrylate such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, Secondary hydroxyl group-containing (meth)acrylates such as 3-chloro-2-hydroxypropyl (meth)acrylate; tertiary hydroxyl group-containing (meth)acrylates such as 2,2-dimethyl 2-hydroxyethyl (meth)acrylate, etc. . These may be used alone or in combination of two or more.

Among the hydroxyl group-containing (meth)acrylates (a1), primary hydroxyl group-containing (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate, 4- Hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc. are preferred, particularly hydroxyl group-containing (meth)acrylates having a hydroxyalkyl group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, especially 2 to 4 carbon atoms. Acrylates, such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, are preferred, especially 2-hydroxyethyl (meth)acrylate.

The content of the hydroxyl group-containing (meth)acrylate (a1) is preferably 5 to 50% by mass, more preferably 8 to 40% by weight, particularly preferably 10 to 35% by weight. It is preferable that the content of the hydroxyl group-containing (meth)acrylate (a1) is within the above range because high adhesiveness can be obtained.

<Alkyl (meth)acrylate (a2)>
Examples of the alkyl (meth)acrylate (a2) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and n-pentyl. (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate , stearyl (meth)acrylate, linear alkyl (meth)acrylate such as icosyl (meth)acrylate; isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, Branched alkyl (meth)acrylate such as isopentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isoicosyl (meth)acrylate, etc. Acrylates include alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate and t-butylcyclohexyl (meth)acrylate.
Among these, from the viewpoint of polymerizability, linear or branched alkyl (meth)acrylates in which the alkyl group has 1 to 20 carbon atoms, particularly 1 to 15 carbon atoms, and even 1 to 10 carbon atoms are preferred, and specifically, , methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred. These may be used alone or in combination of two or more.

In this pressure-sensitive adhesive sheet, the content of alkyl (meth)acrylate (a2) is 50 to 95% by mass based on the entire copolymerization component of the hydroxyl group-containing (meth)acrylic polymer (A). It is preferably 60 to 90% by weight, particularly preferably 65 to 85% by weight. When the content of the alkyl (meth)acrylate (a2) is at least the lower limit, the elastic modulus of the adhesive is maintained, and when it is at most the upper limit, the adhesive properties and reliability are excellent.

In this pressure-sensitive adhesive sheet, a monomer component (a3) copolymerizable with the hydroxyl group-containing (meth)acrylate (a1) and/or the alkyl (meth)acrylate (a2) (excluding the components (a1) and (a2)) Can also be used together. Examples of such monomer component (a3) include ethylenically unsaturated group monomers having functional groups other than hydroxyl groups, other copolymerizable monomers, and the like. These may be used alone or in combination of two or more.

Examples of the ethylenically unsaturated group monomer having a functional group other than the hydroxyl group (hereinafter sometimes referred to as "functional group-containing ethylenically unsaturated monomer") include a functional group-containing monomer having a nitrogen atom, a carboxyl group-containing monomer, Examples include acetoacetyl group-containing monomers, glycidyl group-containing monomers, and the like.
Among these, functional group-containing monomers having a nitrogen atom are preferred, and amino group-containing monomers, amide group-containing monomers, and isocyanate group-containing monomers are still more preferred, from the viewpoint of imparting cohesive force and crosslinking promoting effect. is an amino group-containing monomer.

Examples of the amino group-containing monomer as the functional group-containing monomer having a nitrogen atom include primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate and aminoethyl (meth)acrylate; t-butylamino Secondary amino group-containing (meth)acrylates such as ethyl (meth)acrylate and t-butylaminopropyl (meth)acrylate; ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate , tertiary amino group-containing (meth)acrylates such as dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, and dimethylaminopropylacrylamide.

Examples of the amide group-containing monomer include (meth)acrylamide; N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, Nn-butyl (meth)acrylamide, and diacetone. (meth)acrylamide, N-alkyl (meth)acrylamide such as N,N'-methylenebis(meth)acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-dialkyl(meth)acrylamide such as N,N-ethylmethylacrylamide, N,N-diallyl(meth)acrylamide; N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide Examples include hydroxyalkyl (meth)acrylamides such as acrylamide; alkoxyalkyl (meth)acrylamides such as N-methoxymethyl (meth)acrylamide and N-(n-butoxymethyl)(meth)acrylamide;

Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate and alkylene oxide adducts thereof. The isocyanate group may be protected with a blocking agent such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, and diethyl malonate.

Examples of the carboxy group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, and 2-(meth)acryloyloxypropylhexahydrophthalic acid. (meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropylphthalic acid, 2-(meth)acryloyloxyethylmaleic acid, 2-(meth)acryloyloxypropylmaleic acid, 2-(meth)acryloyloxyethyl Examples include succinic acid, 2-(meth)acryloyloxypropylsuccinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate, and the like.

Examples of the acetoacetyl group-containing monomer include 2-(acetoacetoxy)ethyl (meth)acrylate, allyl acetoacetate, and the like.

Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate, allylglycidyl (meth)acrylate, and the like.

These functional group-containing ethylenically unsaturated monomers may be used alone or in combination of two or more.
The upper limit of the content of the functional group-containing ethylenically unsaturated monomer is determined from the viewpoint of reducing compatibility with the antistatic agent (D) and reducing adhesiveness due to bleed-out. It is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, based on the total copolymerized components of the union (A). The lower limit is usually 0% by mass.

Examples of the other copolymerizable monomers include phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, and phenoxypolyethylene glycol-polypropylene. Aromatic (meth)acrylates such as glycol (meth)acrylate, nonylphenol ethylene oxide adduct (meth)acrylate, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone , 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4 -methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof, etc. (Meth)acrylate with benzophenone structure, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl stearate, vinyl propionate, vinyl acetate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyltoluene, vinylpyridine, vinylpyrrolidone , itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acryl chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, and other vinyl monomers. These may be used alone or in combination of two or more.

The hydroxyl group-containing (meth)acrylic polymer (A) can be obtained by copolymerizing the various monomer components according to conventionally known polymerization methods, such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. .

The hydroxyl group-containing (meth)acrylic polymer (A) used in the present pressure-sensitive adhesive sheet may have a photoactive site, such as a polymerizable carbon double bond group, introduced into the side chain. Thereby, the crosslinking efficiency of the pressure-sensitive adhesive composition [I] can be increased, the pressure-sensitive adhesive composition [I] can be crosslinked in a shorter time, and productivity can be increased.

As a method for introducing a polymerizable carbon double bond group into the side chain of the hydroxyl group-containing (meth)acrylic polymer (A), for example, the above-mentioned hydroxyl group-containing (meth)acrylate (a1) or functional group-containing ethylenic polymer may be used. A copolymer containing a saturated monomer is prepared, and then a compound having a functional group that can react with these functional groups and a polymerizable carbon double bond group is added to the copolymer while maintaining the activity of the polymerizable carbon double bond group. Examples include a method of condensation or addition reaction.

Combinations of these functional groups include epoxy groups (glycidyl groups) and carboxy groups, amino groups and carboxy groups, amino groups and isocyanate groups, epoxy groups (glycidyl groups) and amino groups, hydroxyl groups and epoxy groups, and hydroxyl groups and isocyanate groups. etc. Among these combinations of functional groups, a combination of a hydroxyl group and an isocyanate group is preferred from the viewpoint of ease of reaction control. Among these, a combination in which the copolymer has a hydroxyl group and the compound has an isocyanate group is preferred.

Examples of the isocyanate compound having a polymerizable carbon double bond group include the aforementioned 2-(meth)acryloyloxyethyl isocyanate and alkylene oxide adducts thereof.

The content of the compound having a functional group capable of reacting with the functional group and the polymerizable carbon double bond group is determined from the viewpoint of improving adhesiveness and stress relaxation properties in the hydroxyl group-containing (meth)acrylic polymer (A ) It is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 1 part by mass or less, particularly preferably 0.1 parts by mass or less. Note that the lower limit is usually 0 parts by mass.

The hydroxyl value of the hydroxyl group-containing (meth)acrylic polymer (A) used in the adhesive sheet is preferably 10 mgKOH/g or more, particularly 30 mgKOH/g or more, and more preferably 50 mgKOH/g or more. preferable. Further, the hydroxyl value of the hydroxyl group-containing (meth)acrylic polymer (A) is preferably 120 mgKOH/g or less, particularly preferably 100 mgKOH/g or less, and even more preferably 80 mgKOH/g or less. It is preferable that the hydroxyl value of the hydroxyl group-containing (meth)acrylic polymer (A) is within the above range because adhesiveness is good.

In addition, the hydroxyl value of the (meth)acrylic polymer (A) is measured by the neutralization titration method as follows.
[Hydroxyl value]
Collect 2 g of a sample into an Erlenmeyer flask, add 10 mL of a 1:13 mixed solution of acetic anhydride and pyridine using a whole pipette, and further add 10 mL of toluene. Thereafter, an air cooling tube was attached to the top of the Erlenmeyer flask, and the flask was heated at 95° C. for 90 minutes. After heating, add 10 mL of toluene and 10 mL of pure water, leave to cool while stirring, cool to room temperature (23°C), then add a few drops of phenolphthalein solution, and titrate with 0.1 mol/L potassium hydroxide solution. I do.
Further, as a blank test, the same operation as above was carried out without taking a sample into the Erlenmeyer flask, and the hydroxyl value was calculated based on the following calculation formula (1).
(a formula)
Hydroxyl value = 5.611 x (amount of potassium hydroxide solution used for blank test (mL) - amount of potassium hydroxide solution used for titration (mL)) x f / amount of sample collected (g) + acid value...・(1)
・f: Factor of 0.1 mol/L potassium hydroxide solution

From the viewpoint of adhesiveness, the glass transition temperature (Tg) of the hydroxyl group-containing (meth)acrylic polymer (A) used in the present adhesive sheet is preferably 5°C or lower, more preferably 0°C or lower, and even more preferably Preferably it is -5°C or lower. Note that the lower limit of the glass transition temperature (Tg) is usually -50° C. due to concerns about glue oozing out.

In this adhesive sheet, the glass transition temperature (Tg) of the hydroxyl group-containing (meth)acrylic polymer (A) was determined by measuring dynamic viscoelasticity in shear mode at a frequency of 1 Hz using a dynamic viscoelasticity measuring device. It is determined by reading the temperature at which the loss tangent (loss shear modulus G''/storage shear modulus G'=tan δ) becomes maximum.
For example, a hydroxyl group-containing (meth)acrylic polymer (A) is molded into a cylindrical body with a diameter of 8 mm (height: 1.0 mm), and this is measured using a viscoelasticity measuring device (manufactured by TA Instruments, product name: DHR 2'') can be used to measure the loss tangent (tan δ) under the following measurement conditions.

(Measurement condition)
・Measurement jig: Φ8mm parallel plate ・Distortion: 0.1%
・Frequency: 1Hz
・Measurement temperature: -60 to 100℃
・Heating rate: 5℃/min

The weight average molecular weight (Mw) of the hydroxyl group-containing (meth)acrylic polymer (A) used in this adhesive sheet should be 100,000 or more from the viewpoint of obtaining the adhesive composition [I] with high cohesive strength. is preferable, more preferably 150,000 or more, still more preferably 200,000 or more. In addition, the upper limit of the weight average molecular weight (Mw) of the hydroxyl group-containing (meth)acrylic polymer (A) is preferably 1.2 million or less, more preferably 1 million or less, from the viewpoint of ease of handling and uniform stirring. Below, more preferably below 800,000.

In this pressure-sensitive adhesive sheet, the weight average molecular weight (Mw) can be determined, for example, as follows.
(Method for measuring weight average molecular weight)
The measurement sample was prepared by dissolving 4 mg of hydroxyl group-containing (meth)acrylic polymer (A) using 12 mL of tetrahydrofuran (THF), and a gel permeation chromatography (GPC) analyzer (Tosoh) was used. The weight average molecular weight (Mw) can be determined by measuring the molecular weight distribution curve using HLC-8320GPC (manufactured by Co., Ltd.) under the following conditions.
・Guard column:TSKguardcolumnHXL
・Separation column: TSKgelGMHXL (4 columns)
・Temperature: 40℃
・Injection volume: 100μL
・Polystyrene equivalent ・Solvent: THF
・Flow rate: 1.0mL/min

The hydroxyl group-containing (meth)acrylic polymer (A) used in the present pressure-sensitive adhesive sheet is preferably contained as a main component of the pressure-sensitive adhesive composition [I].

<(meth)acrylate monomer (B)>
The adhesive composition [I] contains a (meth)acrylate monomer (B) in addition to the hydroxyl group-containing (meth)acrylic polymer (A). Thereby, the adhesive composition [I] can form a crosslinked structure and impart cohesive force to the adhesive layer (adhesive sheet).

Examples of the (meth)acrylate monomer (B) used in the pressure-sensitive adhesive sheet include compounds having one or more (meth)acryloyl groups and a radical generating group in the molecule. Among these, compounds having a radical-generating group that is excited by irradiation with active energy rays and generates radicals by causing a hydrogen abstraction reaction are preferred. Specifically, for example, a (meth)acryloyl group and any one of a benzophenone structure, a benzyl structure, an o-benzoylbenzoate structure, a thioxanthone structure, a 3-ketocoumarin structure, a 2-ethylanthraquinone structure, and a camphorquinone structure. More preferred are compounds having one structure or two or more structures.

Among the above, a monofunctional (meth)acrylate monomer (B1) having a benzophenone structure and one (meth)acryloyl group is particularly preferred.
Examples of the monofunctional (meth)acrylate monomer (B1) include 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'- Methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, Examples include 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone and mixtures thereof. Among these, 4-acryloyloxybenzophenone and 4-methacryloyloxybenzophenone are preferred.

Further, a preferable example of the (meth)acrylate monomer (B) used in the present pressure-sensitive adhesive sheet is a polyfunctional (meth)acrylate monomer (B2) having two or more (meth)acryloyl groups.

Examples of the polyfunctional (meth)acrylate monomer (B2) having two or more (meth)acryloyl groups include bifunctional (meth)acrylate monomers and trifunctional or higher (meth)acrylate monomers.

Examples of the difunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9- Alkanediol di(meth)acrylates such as nonanediol di(meth)acrylate, tricyclodecane dimethyloldi(meth)acrylate, bisphenol A ethylene oxide modified di(meth)acrylate, bisphenol F ethylene oxide modified di(meth)acrylate, etc. Examples include bifunctional (meth)acrylates such as bisphenol-modified di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, urethane di(meth)acrylate, and epoxy di(meth)acrylate. Among these, polyethylene glycol di(meth)acrylate is more preferred.

Examples of the trifunctional or higher-functional (meth)acrylate monomers include glycerin tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol. Ethylene oxide such as tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide modified dipentaerythritol hexa(meth)acrylate, ethylene oxide modified pentaerythritol tetra(meth)acrylate, etc. Modified (meth)acrylate, isocyanuric acid ethylene oxide modified tri(meth)acrylate, isocyanuric acid modified tri(meth)acrylate such as ε-caprolactone modified tris(acryloxyethyl)isocyanurate, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer , pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, and other urethane acrylates.

The (meth)acrylate monomer (B) may be used alone or in combination of two or more types, but from the viewpoint of imparting suitable cohesive force, ) It is particularly preferable to contain a monofunctional (meth)acrylate monomer (B1) having an acryloyl group, and the monofunctional (meth)acrylate monomer (B1) having the benzophenone structure and one (meth)acryloyl group. It is more preferable to use the polyfunctional (meth)acrylate monomer (B2) having two or more (meth)acryloyl groups in combination.

The content of the (meth)acrylate monomer (B) is determined based on the hydroxyl group-containing (meth)acrylic polymer ( A) It is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, even more preferably 0.5 part by mass or more, and particularly preferably 1 part by mass or more, based on 100 parts by mass of A). Further, from the viewpoint of adhesiveness, the upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less.

Further, in addition to the (meth)acrylate monomer (B), a thermal crosslinking agent can also be used in combination to further increase the crosslinking density and improve long-term reliability.
Examples of such thermal crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, amine crosslinking agents, and metal chelate crosslinking agents. Among these, it is preferable to use isocyanate-based crosslinking agents because they have excellent reactivity with the hydroxyl group-containing (meth)acrylic polymer (A).

<Photopolymerization initiator (C)>
The photopolymerization initiator (C) used in this adhesive sheet is a compound that generates radicals when exposed to active energy rays, and is broadly classified into two types depending on the radical generation mechanism: the excited initiator and the hydrogen donor in the system. A hydrogen abstraction type photopolymerization initiator (c1) that can form an exciplex and transfer hydrogen from the hydrogen donor, and a cleavage type that can generate radicals by cleaving and decomposing the single bond of the initiator itself. It is broadly classified into photopolymerization initiators (c2).

The photopolymerization initiator (C) may be either a hydrogen abstraction type photopolymerization initiator (c1) or a cleavage type photopolymerization initiator (c2), and each can be used alone or by mixing the two. may be used, or each may be used alone or in combination of two or more, but in this adhesive sheet, the hydroxyl group-containing (meth)acrylic polymer (A) itself contains a polymerizable carbon double bond group. It is preferable to use a hydrogen abstraction type photopolymerization initiator (c1) because it can crosslink efficiently without requiring a functional group such as.
In addition, from the point of view of imparting excellent cohesive force, it is necessary to use hydrogen together with an acrylate monomer having a benzophenone structure, such as the monofunctional (meth)acrylate monomer (B1) having a benzophenone structure and one (meth)acryloyl group. It is particularly preferable to use a pultrusion type photopolymerization initiator (c1).

Examples of the hydrogen abstraction type photopolymerization initiator (c1) include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, -(meth)acryloyloxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylformate (methylbenzoylformate), bis(2-phenyl-2-oxoacetic acid)oxybisethylene, 4-(1,3-acryloyl-1) , 4,7,10,13-pentaoxotridecyl)benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butyl Examples include anthraquinone, 2-aminoanthraquinone and derivatives thereof. Among these, methyl benzoyl formate is preferred.

Examples of the cleavable photopolymerization initiator (c2) include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2 -Hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), Methyl phenylglyoxylic acid, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopro Pan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6- (trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)2,4,4- Examples include trimethylpentylphosphine oxide and derivatives thereof.

The photopolymerization initiator (C) used in this pressure-sensitive adhesive sheet may be used alone, or two or more types may be used in combination.

The content of the photopolymerization initiator (C) used in the present pressure-sensitive adhesive sheet is usually preferably 0.1 parts by mass or more, and 0.1 parts by mass or more, based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). The amount is more preferably 5 parts by mass or more, and even more preferably 1 part by mass or more. Moreover, the upper limit is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 4 parts by mass or less. When the content is at least the lower limit, curing failure tends to be prevented, and when it is at most the upper limit, it is easy to prevent deterioration in solution stability such as precipitation from the adhesive composition [I], and it tends to prevent embrittlement and embrittlement. There is a tendency to easily suppress coloring problems.

<Nitrogen or phosphorus atom-containing antistatic agent (D)>
The antistatic agent used in this pressure-sensitive adhesive sheet is an antistatic agent containing a nitrogen atom or a phosphorus atom (D) because of its compatibility with the hydroxyl group-containing (meth)acrylic polymer (A) and excellent antistatic performance. It is important that there be. The nitrogen or phosphorus atom-containing antistatic agent (D) is a salt consisting of a nitrogen or phosphorus atom-containing cation and an anion. The nitrogen atom- or phosphorus atom-containing antistatic agent (D) may be used alone or in combination of two or more.

(nitrogen atom-containing cation)
Examples of the nitrogen atom-containing cations include quaternary ammonium cations (particularly non-cyclic quaternary ammonium cations), imidazolium cations, pyridinium cations, piperidinium cations, pyrimidinium cations, pyrazolium cations, and pyrrolidinium cations. etc.

Examples of quaternary ammonium cations include:
Tetraalkylammonium cations in which the alkyl chain lengths of the alkyl groups are all the same, such as tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, and tetraheptylammonium cation;
Triethylmethylammonium cation, tributylethylammonium cation, trimethylpropylammonium cation, trimethyldecylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, N,N-dimethyl-N-ethyl-N-propylammonium cation, N,N- Dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl-N-ethyl-N-hexylammonium cation, N,N-dimethyl- N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N,N-dipropylammonium cation, N,N-diethyl-N-propyl -N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl-N-hexylammonium cation, N,N-dimethyl-N-propyl-N -heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-diethyl-N-butyl-N-heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexyl Ammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N-propylammonium cation, N,N-diethyl-N-methyl-N- Pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation , N,N-dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N , N-dipropyl-N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation , a tetraalkylammonium cation having alkyl groups with different alkyl chain lengths, such as N-methyl-N-ethyl-N-propyl-N-pentylammonium cation;
In addition, it has a substituent having an aromatic ring or an ether bond, such as glycidyltrimethylammonium cation, diallyldimethylammonium cation, benzyltributylammonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, etc. Examples include ammonium cations with substituents.

Examples of imidazolium cations include 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1- Hexyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methyl imidazolium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2, Examples include 3-dimethylimidazolium cation.

Examples of pyridinium cations include 1-octyl-2-methylpyridinium cation, 1-octyl-3-methylpyridinium cation, 1-octyl-4-methylpyridinium cation, 1-octylpyridinium cation, 2-ethylhexylpyridinium cation, 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl-3-methylpyridinium cation, 1-hexyl-4-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1 -propylpyrrolidinium cation and the like.

Examples of piperidinium cations include 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-butylpiperidinium cation, 1-butyl-1-butylpiperidinium cation, 1-occl-1- Examples include octylpiperidinium cation and 1-butyl-1-octylpiperidinium cation.

Examples of pyrimidinium cations include 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, 1,2,3,4-tetramethyl- Examples include 1,6-dihydropyrimidinium cation.

Examples of the pyrazolium cation include 1-methylpyrazolium cation, 3-methylpyrazolium cation, and 1-ethyl-2-methylpyrazolinium cation.

Examples of pyrrolidinium cations include 1-dimethylpyrrolidinium, 1-methyl-1-ethylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, 1- Methyl-1-pentylpyrrolidinium, 1-methyl-1-hexylpyrrolidinium, 1-methyl-1-heptylpyrrolidinium, 1-ethyl-1-propylpyrrolidinium, 1-ethyl-1-butyl Pyrrolidinium, 1-ethyl-1-pentylpyrrolidinium, 1-ethyl-1-hexylpyrrolidinium, 1-ethyl-1-heptylpyrrolidinium, 1,1-dipropylpyrrolidinium, 1 -propyl-1-butylpyrrolidinium, 1,1-dibutylpyrrolidinium and the like.

In addition, as nitrogen atom-containing cations, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, 4-(2-ethoxyethyl)-4-methylmorpholinium cation etc.

(phosphorus atom-containing cation)
Examples of the phosphorus atom-containing cations include phosphonium cations.

Examples of the phosphonium cations include 1,1,1-tributyl-1-dodecylphosphonium cation, tributyl-n-octylphosphonium, tetraphenylphosphonium, tetraethylphosphonium, tetra-n-octylphosphonium, methyltriphenylphosphonium, and isopropyl. Examples include triphenylphosphonium, methoxycarbonylmethyl (triphenyl)phosphonium, ethyltriphenylphosphonium, butyltriphenylphosphonium, (1-naphthylmethyl)triphenylphosphonium cation, and the like.

Among the nitrogen atom-containing cations or phosphorus atom-containing cations, nitrogen atoms substituted with at least one alkyl group or Cations containing phosphorus atoms are preferred. Among these, ammonium-based cations, pyridinium-based cations, and phosphonium-based cations are preferred, and ammonium-based cations are particularly preferred from the viewpoint of excellent antistatic performance.

Among the ammonium-based cations, quaternary ammonium cations are preferred, and tetraalkylammonium cations in which each of the four substituents is substituted with an alkyl group are preferred, and in particular, the crystallinity of the ionic compound is Tetraalkylammonium cations having alkyl groups with different alkyl chain lengths are preferred because they have low compatibility with the hydroxyl group-containing (meth)acrylic resin (A) and are difficult to precipitate from the adhesive layer at low temperatures. .

Among the above-mentioned tetraalkylammonium cations, tetraalkylammonium cations having a total carbon number of 4 to 48 are preferred, particularly preferred are tetraalkylammonium cations having a total carbon number of 8 to 32, and more preferably 10 to 16 carbon atoms. Tetraalkylammonium cations are preferred. If the total number of carbon atoms is too large or too small, the compatibility with the hydroxyl group-containing (meth)acrylic resin (A) tends to decrease.

(anion)
As the anion, for example,
Tetrafluoroborate anion [BF ₄ ^- ],
hexafluorophosphate anion [PF ₆ ^- ],
hexafluoroarsenate anion [AsF ₆ ^- ],
hexafluoroantimonate anion [SbF ₆ ^- ],
hexafluoroniobate anion [NbF ₆ ^- ],
Hexafluorotantalate anion [TaF ₆ ^- ],
fluorine-containing inorganic anions such as;
N,N-bis(fluorosulfonyl)imide anion [(SO ₂ F) ₂ N ^- ],
N,N-bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ], N,N-bis(pentafluoroethanesulfonyl) imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ^- ] fluorine-containing bis(perfluoroalkanesulfonyl)imide anions such as
(trifluoromethanesulfonyl) (trifluoromethanecarbonyl) imide anion [(CF ₃ SO ₂ ) (CF ₃ CO) N ⁻ ] and other fluorine-containing imide anions other than the above,
fluorine-containing imide anions such as;
Trifluoroacetate anion [CF ₃ COO ^- ],
Trifluoromethanesulfonate anion [CF ₃ SO ₃ ^- ]
Perfluorobutane sulfonate anion [C ₄ F ₉ SO ₃ ^- ],
Perfluorobutanoate anion [C ₃ F ₇ COO ^- ],
Tris (trifluoromethanesulfonyl) methanide anion [(CF ₃ SO ₂ ) ₃ C ^- ],
etc.

Among the above, fluorine-containing imide anions are preferred because they have excellent antistatic properties, have low melting points, and are easy to handle. Particularly preferred are N,N-bis(perfluoroalkanesulfonyl) imides, and specific Preferred examples include N,N-bis(trifluoromethanesulfonyl)imide and N,N-bis(pentafluoroethanesulfonyl)imide.

The antistatic agent (D) used in this pressure-sensitive adhesive sheet can be appropriately selected from the combination of the cationic component and the anionic component, but among them, (meth)acryloyl group, Antistatic agents that do not have polymerizable groups such as vinyl groups are preferred, and among them, a combination of one type of cation selected from the group consisting of quaternary ammonium cations, pyridinium cations, and phosphonium cations and a fluorine-containing imide anion. It is preferable to use an antistatic agent that does not have a polymerizable group.

The melting point of the antistatic agent (D) used in the adhesive sheet is preferably 100°C or lower, more preferably 0°C to 90°C, even more preferably 10°C to 80°C, particularly preferably 15°C to 70°C. °C, particularly preferably from 20°C to 50°C. If the melting point is too high, the antistatic agent tends to precipitate under low temperature conditions. The melting point of the antistatic agent (D) is usually measured using a differential scanning calorimeter (DSC) and is listed in the catalogs of each company.

The content of the antistatic agent (D) used in the present pressure-sensitive adhesive sheet is preferably 0.1 part by mass or more, more preferably The amount is 1 part by mass or more, more preferably 1.5 parts by mass or more. The upper limit is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic resin (A). If the content of the antistatic agent (D) is too small, sufficient antistatic performance may not be obtained, and if the content is too large, the adhesive performance tends to deteriorate.

<Silane coupling agent (E)>
The silane coupling agent (E) used in the present pressure-sensitive adhesive sheet is an organosilicon compound containing one or more reactive functional groups and one or more alkoxy groups bonded to silicon atoms in its structure. Examples of the reactive functional groups include epoxy groups, (meth)acryloyl groups, mercapto groups, hydroxyl groups, carboxy groups, amino groups, amide groups, and isocyanate groups. Epoxy groups and mercapto groups are preferred.

The alkoxy group bonded to the silicon atom preferably contains an alkoxy group having 1 to 8 carbon atoms from the viewpoint of durability and storage stability, and particularly preferably a methoxy group or an ethoxy group. Note that the silane coupling agent may have a reactive functional group and an organic substituent other than the alkoxy group bonded to a silicon atom, such as an alkyl group or a phenyl group.

Examples of the silane coupling agent (E) used in this adhesive sheet include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, Monomer-type epoxy group-containing silane coupling agents such as silane compounds such as glycidoxypropylmethyldimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and some of the silane compounds are hydrolyzed and condensed. Oligomeric epoxy group-containing silane coupling, which is a silane compound that is polymerized or co-condensed with the silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. agent; a monomer type mercapto group-containing silane coupling agent which is a silane compound such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, 3-mercaptopropylmethyldimethoxysilane; , a silane in which a part of the silane compound is hydrolyzed and polycondensed, or the silane compound is co-condensed with an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. Oligomeric mercapto group-containing silane coupling agent which is a compound; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, (Meth)acryloyl group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-amino Propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltri Examples include amino group-containing silane coupling agents such as methoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane; vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane. It will be done.

The silane coupling agent (E) used in this pressure-sensitive adhesive sheet may be used alone or in combination of two or more.

Among these, epoxy group-containing silane coupling agents and mercapto group-containing silane coupling agents are preferably used from the viewpoint of excellent durability, and epoxy group-containing silane coupling agents are particularly preferred.

The content of the silane coupling agent (E) used in the present adhesive sheet is preferably 0.005 parts by mass or more based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A), The amount is more preferably 0.01 parts by mass or more, and even more preferably 0.05 parts by mass or more. The upper limit is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 1 part by mass or less, based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic resin (A). When the content is at least the lower limit, durability tends to improve, and when the content is at most the upper limit, durability tends to improve.

<Other ingredients>
Adhesive composition [I] may contain, as necessary, as "other components" to the extent that the effects of the present invention are not impaired, for example, (meth)acrylic polymers other than the above (A), the above (D) In addition to other antistatic agents, plasticizers, ultraviolet absorbers, rust preventives, tackifying resins, antioxidants, light stabilizers, metal deactivators, anti-aging agents, moisture absorbers, rust preventives, and inorganic It is possible to appropriately contain various additives such as particles.
Further, if necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained. These can be used alone or in combination of two or more.

(Plasticizer)
A plasticizer is a material that improves processability and flexibility by softening a resin with a high elastic modulus. Examples of the plasticizer include monofunctional (meth)acrylic oligomers such as polyester (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate. Among these, urethane (meth)acrylate oligomers are preferred from the viewpoint of imparting appropriate toughness to the cured product.

(Ultraviolet absorber)
Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, triazine UV absorbers, salicylic acid UV absorbers, cyanoacrylate UV absorbers, and benzoxazine UV absorbers. These ultraviolet absorbers can be used alone or in combination of two or more.

The content of the ultraviolet absorber is preferably 0.01 to 20 parts by mass, particularly preferably 0.1 to 15 parts by mass, per 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). parts, more preferably 0.5 to 10 parts by weight. When the content is at least the lower limit, light resistance reliability tends to improve, and when the content is at most the upper limit, yellowing resistance tends to improve.

(anti-rust)
As the rust preventive agent, for example, triazoles, benzotriazoles, etc. are preferable, and can prevent corrosion of the optical member.
The content of the rust preventive agent is preferably 0.01 to 5 parts by mass, particularly 0.1 to 3 parts by mass, per 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). It is preferable.

The content of the other components is preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and still more preferably 0. It is 5 parts by mass or less, and the lower limit is usually 0 parts by mass. If this content is too large, the compatibility with the hydroxyl group-containing (meth)acrylic polymer (A) tends to decrease, and the durability tends to decrease.

Adhesive composition [I] preferably contains a hydroxyl group-containing (meth)acrylic polymer (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), and a nitrogen atom or phosphorus atom-containing It is prepared by mixing predetermined amounts of the antistatic agent (D) and, if necessary, other components such as a silane coupling agent (E), an ultraviolet absorber, and a rust preventive.
The pressure-sensitive adhesive composition [I] thus obtained is used as a pressure-sensitive adhesive sheet, particularly a pressure-sensitive adhesive sheet used for laminating components of an image display device.

<Configuration>
The present adhesive sheet may be a single-layer sheet consisting only of an adhesive layer formed from the adhesive composition [I] (also referred to as "main adhesive layer"), or a multilayer sheet in which a plurality of main adhesive layers are laminated. It may be a sheet. Alternatively, it may be a multilayer sheet in which the main adhesive layer and an adhesive layer other than the main adhesive layer are laminated.

<Physical properties of this adhesive sheet>
This pressure-sensitive adhesive sheet can have the following physical properties.

(Surface resistivity)
The surface resistivity of the pressure-sensitive adhesive sheet is preferably 1.0×10 ¹¹ Ω/□ or less, more preferably 9.5×10 ¹⁰ Ω/□ or less. The surface resistivity (Ω/□) can be measured, for example, under the measurement conditions described in Examples below.

(adhesive strength)
The adhesive force of the present adhesive sheet to a member (peel angle 180°: peel speed 60 mm/min) is preferably 1 to 30 N/cm, more preferably 3 to 25 N/cm, even more preferably It is 5 to 20 N/cm. Within this range, there is sufficient adhesiveness and there is a tendency for it to be suitably used as a pressure-sensitive adhesive sheet for image display devices.

(Total light transmittance, haze)
The total light transmittance of the adhesive sheet is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

Further, the haze of the pressure-sensitive adhesive sheet is preferably 1.0% or less, more preferably 0.8% or less, particularly preferably 0.5% or less.
Since the haze of the adhesive sheet is 1.0% or less, it can be used for image display devices.
In order to keep the haze of the adhesive sheet within the above range, it is preferable that the adhesive sheet does not contain particles such as organic particles.
The total light transmittance and haze can be measured, for example, under the measurement conditions described in Examples below.

(gel fraction)
The gel fraction of the pressure-sensitive adhesive sheet is preferably 30 to 95% by mass, more preferably 50 to 90% by mass, and even more preferably 52 to 85% by mass. When the gel fraction of the present pressure-sensitive adhesive sheet is at least the lower limit value, the shape can be sufficiently maintained, and when it is at most the upper limit value, the adhesive force can be increased.
The gel fraction is a measure of the degree of crosslinking (degree of curing), and can be measured under the measurement conditions described in Examples below.

<Thickness>
The thickness of this adhesive sheet is not particularly limited, and if the thickness is 10 μm or more, handling properties are good, and if the thickness is 1000 μm or less, it will contribute to making the adhesive sheet thinner. be able to.
Therefore, the thickness of the pressure-sensitive adhesive sheet is preferably 10 μm or more, particularly 15 μm or more, particularly 20 μm or more, and even more preferably 25 μm or more.
On the other hand, the upper limit is preferably 1000 μm or less, particularly preferably 500 μm or less, particularly 250 μm or less, further preferably 100 μm or less, particularly 60 μm or less.

<Preferred use of this adhesive sheet>
This adhesive sheet is used for laminating members that constitute image display devices such as displays, and is suitable for image display panels such as liquid crystal displays (LCD), plasma displays (PDP), electroluminescent displays (ELD), etc. It is useful as an adhesive component between a protective panel and a touch panel member disposed on the front side (viewing side).

<Production method of this adhesive sheet>
Next, a method for manufacturing the present pressure-sensitive adhesive sheet will be explained.
However, the following explanation is an example of a method for manufacturing the present pressure-sensitive adhesive sheet, and the present pressure-sensitive adhesive sheet is not limited to those manufactured by such a manufacturing method.

In producing the present pressure-sensitive adhesive sheet, preferably a hydroxyl group-containing (meth)acrylic polymer (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), a nitrogen atom- or phosphorus atom-containing antistatic A pressure-sensitive adhesive composition [I] for forming the present pressure-sensitive adhesive sheet containing the agent (D), a silane coupling agent (E) as necessary, other components, etc. is prepared, and the pressure-sensitive adhesive composition [I] is The pressure-sensitive adhesive sheet may be produced by forming it into a sheet, curing it by crosslinking, that is, polymerizing it, and subjecting it to appropriate processing as necessary.

In addition, in producing the present pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition [I] for forming the pressure-sensitive adhesive sheet is prepared in the same manner as described above, and this is coated on a member sheet, and the pressure-sensitive adhesive composition [I] is coated on a member sheet. The adhesive sheet may be formed by curing.
However, it is not limited to this method.

When preparing the adhesive composition [I] for forming the present adhesive sheet, the raw materials are mixed in a temperature-adjustable kneader (e.g., single-screw extruder, twin-screw extruder, planetary mixer, twin-screw mixer, pressure kneader). etc.) for kneading.
In addition, when mixing various raw materials, various additives such as silane coupling agent (E) and antioxidant may be blended with the resin in advance and then supplied to the kneading machine, or all materials may be mixed in advance. The resin may be supplied after being melt-mixed, or a masterbatch in which only the additives are concentrated in advance in the resin may be prepared and supplied.

Methods for forming the adhesive composition [I] into a sheet include known methods, such as wet lamination, dry lamination, extrusion casting using a T-die, extrusion lamination, calendaring, inflation, and injection molding. , liquid injection curing method, etc. can be adopted. Among these, wet lamination, extrusion casting, and extrusion lamination are suitable for manufacturing sheets.

Moreover, it is preferable that the adhesive composition [I] has a photocurable property that produces a cured product by irradiating and curing active energy rays. In addition to irradiation with active energy rays, further curing can also be achieved by heating.
In particular, the present pressure-sensitive adhesive sheet can be produced by irradiating active energy rays to a molded object, such as a sheet, of the pressure-sensitive adhesive composition [I]. In addition to irradiation with active energy rays, further curing can also be achieved by heating.

Moreover, the irradiation energy, irradiation time, irradiation method, etc. of the active energy rays are not particularly limited, as long as they can activate the photopolymerization initiator (C) and polymerize the monomer components.
When a hydrogen abstraction type photopolymerization initiator (c1) is used as the photopolymerization initiator (C), a hydrogen abstraction reaction also occurs from the hydroxyl group-containing (meth)acrylic polymer (A), resulting in a hydroxyl group-containing (meth)acrylic polymer. The system polymer (A) is incorporated into the crosslinked structure, and a crosslinked structure with many crosslinking points can be formed.
Therefore, it is preferable that the pressure-sensitive adhesive sheet is cured using a hydrogen abstraction type photopolymerization initiator.

Moreover, as another embodiment of the method for producing the present pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition [I] can be dissolved in an appropriate solvent and various coating methods can be used.
When a coating method is used, the present pressure-sensitive adhesive sheet can also be obtained by thermal curing in addition to curing by irradiation with active energy rays as described above. In the case of coating, the thickness of the adhesive sheet can be adjusted by the coating thickness and the solid content concentration of the coating liquid.

For example, the adhesive composition [I] can be dissolved in a solvent, coated on a release film, dried, and cured by active energy ray irradiation to form the adhesive sheet. Furthermore, a release film may be laminated as necessary. In this case, the release film may be coated and dried, cured by active energy ray irradiation, and the release film may be laminated thereon, or the release film may be coated and dried, and the release film After laminating, the adhesive sheet may be formed by curing by irradiation with active energy rays.

Such a solvent is not particularly limited as long as it dissolves the adhesive composition [I], and examples thereof include ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate, acetone, methyl ethyl ketone, Examples include ketone solvents such as methyl isobutyl ketone, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol. These can be used alone or in combination of two or more. Among these, ethyl acetate, acetone, methyl ethyl ketone, and toluene are preferred from the viewpoint of solubility, drying properties, cost, etc., and ethyl acetate is particularly preferably used.

From the viewpoint of drying properties, the content of the solvent is preferably 600 parts by mass or less, more preferably 500 parts by mass or less, and 400 parts by mass or less with respect to 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). More preferably, the amount is particularly preferably 300 parts by mass or less. On the other hand, it is preferably 1 part by mass or more, more preferably 50 parts by mass or more, even more preferably 100 parts by mass or more, and particularly preferably 150 parts by mass or more.
As a coating method, conventional methods such as roll coating, die coating, gravure coating, comma coating, screen printing, and bar coating can be used.

The solvent content in the adhesive composition [I] after drying is preferably 1% by mass or less, more preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less, Most preferably it is 0% by mass.

The drying temperature is usually 40 to 150°C, more preferably 45 to 140°C, even more preferably 50 to 130°C, particularly preferably 55 to 120°C. Within the above temperature range, the solvent can be removed efficiently and relatively safely while suppressing thermal deformation of the release film.

The drying time is usually 1 to 30 minutes, more preferably 3 to 25 minutes, still more preferably 5 to 20 minutes. Within the above time range, the solvent can be removed efficiently and sufficiently.

Examples of the drying method include drying using a dryer, heating rolls, and drying by blowing hot air onto the film. Among these, it is preferable to use a dryer because drying can be done uniformly and easily. These can be used alone or in combination of two or more.

Examples of active energy rays in the active energy ray irradiation include far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, visible rays, etc., X-rays, α-rays, β-rays, γ-rays, electron beams, proton beams, neutron beams, etc. ionizing radiation. Among these, ultraviolet light is preferred from the viewpoint of suppressing damage to optical device components and controlling reactions. In addition, curing by ultraviolet irradiation is advantageous in terms of curing speed, availability of irradiation equipment, price, etc.

Examples of light sources for ultraviolet irradiation include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, electrodeless discharge lamps, LEDs, etc. that emit light in the wavelength range of 150 to 450 nm. It will be done. Among these, it is preferable to use a high-pressure mercury lamp.

From the viewpoint of curing, the active energy ray irradiation amount (cumulative light amount) is preferably 30 to 3000 mJ/cm ² , more preferably 100 to 2000 mJ/cm ² , and still more preferably 300 to 1500 mJ/cm ² .
After irradiation with active energy rays, heating can be performed as necessary to increase the degree of curing.

A release film can also be provided on at least one side of the pressure-sensitive adhesive sheet obtained above from the viewpoint of preventing blocking and foreign matter adhesion.

As such a release film, a known release film can be used as appropriate.
Examples of the material of the release film include polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, triacetyl cellulose film, fluororesin film, etc., which are coated with silicone resin and subjected to release treatment. A release paper or the like can be appropriately selected and used.

The thickness of the release film is not particularly limited. Among these, from the viewpoint of processability and handling, it is preferably 10 to 250 μm, more preferably 25 to 200 μm, and even more preferably 35 to 190 μm.

Further, if necessary, embossing or various unevenness processing (conical, pyramidal, hemispherical, etc.) processing may be performed. Further, for the purpose of improving adhesion to various member sheets, the surface may be subjected to various surface treatments such as corona treatment, plasma treatment, and primer treatment.

The present pressure-sensitive adhesive sheet can also be provided as a pressure-sensitive adhesive sheet with a release film by laminating a release film on one or both sides of the pressure-sensitive adhesive layer (present pressure-sensitive adhesive sheet) made of the pressure-sensitive adhesive composition [I].

<Laminated body for configuring this image display device>
A laminate for configuring an image display device according to an example of an embodiment of the present invention (hereinafter sometimes referred to as "this laminate") has the present adhesive sheet interposed between two image display device constituent members, and the two This is a laminate for configuring an image display device having a structure in which two image display device component members are laminated with the adhesive sheet interposed therebetween.
In addition, in this laminate, by irradiating the adhesive sheet with active energy rays, the adhesive sheet is cured (the adhesive sheet after curing is referred to as the "adhesive sheet after curing"), and two Image display device components can be joined.

In this case, the two image display device constituent members include at least one of the two constituent members selected from the group consisting of a touch sensor, an image display panel, a surface protection panel, a polarizing film, and a retardation film. A laminate consisting of a combination of the above may be mentioned.

In addition, the image display device constituent members include various members constituting the image display device and are not particularly limited, but include, for example, a flexible display such as an organic electroluminescence (EL) display, a cover lens (cover film), and a polarizing plate. Displays such as polarizers, retardation films, barrier films, viewing angle compensation films, brightness enhancement films, contrast enhancement films, diffusion films, transflective films, electrode films, transparent conductive films, metal mesh films, touch sensor films, etc. Examples include flexible members for Any one of these or a combination of two of these may be used.

<Method for manufacturing this laminate>
The method for producing the present laminate is not particularly limited, and may be formed by applying the adhesive composition [I] onto the constituent members of the image display device, or may be formed by applying the adhesive composition [I] in advance to the constituent members of the image display device. ] After forming a pressure-sensitive adhesive sheet using the adhesive sheet, it may be bonded to a constituent member of an image display device.

<<Main image display device>>
An image display device according to an example of an embodiment of the present invention (hereinafter sometimes referred to as “this image display device”) is an image display device incorporating the present adhesive sheet or the present laminate. For example, the present image display device including the present adhesive sheet can be formed by laminating the present adhesive sheet on other image display device constituent members.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.
In addition, in the examples, "parts" and "%" mean mass standards.

<Raw materials>
First, details of each material component of the adhesive composition used in Examples and Comparative Examples will be explained.

<Acrylic polymer>
・(A-1): Hydroxyl group-containing acrylic polymer [monomer composition: 2-ethylhexyl acrylate/hydroxyethyl acrylate/methyl acrylate/ethyl acrylate copolymer (45/15/15/25 (mass%)), glass Transition temperature (Tg): -9°C, weight average molecular weight (Mw): 230,000, hydroxyl value: 62mgKOH/g]
・(A'-1): Carboxy group-containing acrylic polymer [monomer composition: butyl acrylate/2-ethylhexyl acrylate/acrylic acid copolymer (78/20/2 (mass%)), glass transition temperature (Tg ): -36℃, weight average molecular weight (Mw): 400,000]

<(meth)acrylate monomer>
・(B1-1): Methacryloyloxybenzophenone (manufactured by Shinryosha, molecular weight: 266, melting point: 70°C)
・(B2-1): Polypropylene glycol diacrylate (“NK Ester APG400” manufactured by Shin Nakamura Chemical Co., Ltd., viscosity: 35 mPa・s)

<Photopolymerization initiator>
・(C-1): Methyl benzoyl formate (manufactured by IGM)

<Antistatic agent>
・(D-1): Pyridine cation (“IL-P14” manufactured by Koei Chemical Co., Ltd.)
・(D-2): Phosphonium cation (“IL-AP3” manufactured by Koei Chemical Co., Ltd.)
・(D-3): Ammonium cation (tri-n-butylmethylammonium=N,N-(trifluoromethanesulfonyl)imide) (“FC-4400” manufactured by 3M, melting point 27.5°C)

<Silane coupling agent>
・(E-1): Epoxysilane (“KBM-403” manufactured by Shin-Etsu Silicone Co., Ltd.)

(Examples 1-7, Comparative Examples 1-2)
Each component was uniformly melted and kneaded to prepare a pressure-sensitive adhesive composition according to the formulation shown in Table 1.

The adhesive composition obtained above was coated with two release films (release-treated polyethylene terephthalate film ("Diafoil MRF" manufactured by Mitsubishi Chemical Corporation, thickness 75 μm/"Diafoil MRT" manufactured by Mitsubishi Chemical Corporation, thickness 38 μm). )) and formed into a sheet at a temperature of 80°C to a thickness of 100 μm, and the cumulative amount of light at a wavelength of 365 nm is 2000 mJ/cm ² from one release film side (“Diamond Foil MRF” side). A pressure sensitive adhesive sheet (adhesive sheet laminate) sandwiched between release films was prepared by irradiating light with a high-pressure mercury lamp to pre-cure.
Note that the adhesive layer in the adhesive sheet laminate had room to be photocured by light irradiation (precured product).
The obtained pressure-sensitive adhesive sheet was evaluated as follows.

<Surface resistivity>
One release film (“Diafoil MRT” side) of the adhesive sheet laminates produced in Examples and Comparative Examples was peeled off, and a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil T100, thickness 125 μm) was pasted as a backing film. A laminate was produced by combining the two.
Next, the laminate was subjected to autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes), and then ultraviolet rays were applied from the release film side (“diafoil MRF” side) until the cumulative light intensity at 365 nm was 3000 mJ/cm. After curing by irradiation to obtain a surface resistivity of ² , the sample was cured at 23° C. and 50% RH for 15 hours to prepare a surface resistivity measurement sample.
After cutting the obtained surface resistivity measurement sample to 100 mm in length and 100 mm in width, peel off the remaining release film and place the exposed adhesive surface against the electrode of a cell for surface resistance measurement. The surface resistivity (Ω/□) was measured after applying a voltage of 500 V for 1 minute using “Hiresta HP4339B” manufactured by Seiko Analytech Co., Ltd., and the surface resistivity was evaluated based on the following criteria.
〇…Surface resistivity is 1.0×10 ¹¹ Ω/□ or less ×…Surface resistivity is over 1.0×10 ¹¹ Ω/□

<Adhesive strength>
One of the release films ("Diafoil MRT" side) of the adhesive sheet laminates produced in Examples and Comparative Examples was peeled off, and a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil T100, thickness 100 μm) was pasted as a backing film. A laminate was produced by combining the two.
After cutting the obtained laminate to a length of 100 mm and a width of 10 mm, the remaining release film was peeled off and the exposed adhesive surface was roll-bonded to soda lime glass. The bonded product was subjected to autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes), and then cured by irradiating ultraviolet rays from the soda lime glass side so that the cumulative amount of light at 365 nm was 3000 mJ/cm ² Thereafter, it was cured for 15 hours at 23° C. and 50% RH, and was used as a sample for peel force measurement.
The obtained peel force measurement sample was peeled off at a peel angle of 180° and a peel speed of 60 mm/min, and the peel force (N/cm) against soda lime glass was measured, and the adhesive strength was evaluated based on the following criteria. .
◎... Peeling force is 15 N/cm or more 〇... Peeling force is 10 N/cm or more and less than 15 N/cm ×... Peeling force is less than 10 N/cm

<Total light transmittance and haze>
After cutting the adhesive sheet laminate to a length of 100 mm and a width of 70 mm, the release film was sequentially peeled off and roll laminated to both the front and back sides of soda lime glass (82 mm x 53 mm x 0.5 mm thickness), and both sides protruding from the glass were cut. The adhesive sheet was cut, and the bonded product was subjected to autoclave treatment (60° C., gauge pressure 0.2 MPa, 20 minutes) to prepare a sample for measuring optical properties.
Regarding the obtained optical property measurement sample, the total light transmittance was measured according to JIS K7361-1 and the haze value was measured according to JIS K7136 using a haze meter (NDH5000 manufactured by Nippon Denshoku Kogyo Co., Ltd.). The evaluation criteria for each are as follows.
(Total light transmittance)
〇...90% or more ×...less than 90% (haze value)
〇・・・Less than 1% ×・・・1% or more

<Gel fraction>
The release film was removed from the adhesive sheet laminates produced in Examples and Comparative Examples, and a laminate with a thickness of 1.0 mm was obtained by laminating multiple layers of adhesive sheets, and then a cylindrical body with a diameter of 8 mm was punched out, and this was used as a sample. The sample was wrapped in a 200 mesh SUS wire mesh and immersed in ethyl acetate adjusted to 23°C for 72 hours. Thereafter, it was dried at 75° C. for 4.5 hours, and the mass of the adhesive before and after immersion in ethyl acetate was measured, and the difference between the two masses was taken as the mass of the undissolved adhesive remaining in the wire mesh. The mass percentage of the undissolved adhesive remaining in the wire mesh with respect to the mass of the adhesive before immersion in ethyl acetate was calculated as the gel fraction (%).
〇...60% or more △...50% or more and less than 60% ×...less than 50%

Table 1 shows the evaluation results of Examples and Comparative Examples.
In addition, in each example and comparative example of Table 1, the numerical value described in each item of an adhesive composition is mass parts.

From the above evaluation results, the adhesive sheets produced in Examples 1 to 7 had excellent adhesive properties and optical properties, and also had excellent antistatic performance. Further, the degree of crosslinking (gel fraction) was also good.

On the other hand, Comparative Example 1 did not contain an antistatic agent, so the surface resistivity was high, and the antistatic performance could not be satisfied. Comparative Example 2 was a (meth)acrylic polymer that did not contain hydroxyl groups, and had poor adhesive strength as a pressure-sensitive adhesive sheet. That is, by using a hydroxyl group-containing (meth)acrylic polymer as the acrylic polymer and combining it with the antistatic agent, the compatibility between the antistatic agent and the hydroxyl group-containing (meth)acrylic polymer becomes good, resulting in transparent This adhesive sheet has excellent adhesive properties, adhesive strength, and antistatic properties.

In addition, the laminates for forming image display devices produced using the adhesive sheets of Examples 1 to 7 had excellent adhesive properties and optical properties, and also had excellent antistatic performance.

The pressure-sensitive adhesive sheet of the present invention not only has excellent adhesive strength and transparency, but also has excellent antistatic performance, which reduces the accumulation of electric charge caused by friction, and, for example, eliminates the occurrence of edge display defects. This is a useful adhesive sheet.

Claims (14)

Adhesive composition containing a hydroxyl group-containing (meth)acrylic polymer (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C), and a nitrogen or phosphorus atom-containing antistatic agent (D) An adhesive sheet formed from the product [I]. The adhesive sheet according to claim 1, wherein the hydroxyl group-containing (meth)acrylic polymer (A) has a hydroxyl value of 10 to 120 mgKOH/g. The adhesive sheet according to claim 1 or 2, wherein the (meth)acrylate monomer (B) includes a monofunctional (meth)acrylate monomer (B1) having a benzophenone structure and one (meth)acryloyl group. The (meth)acrylate monomer (B) according to any one of claims 1 to 3, wherein the (meth)acrylate monomer (B) includes a polyfunctional (meth)acrylate monomer (B2) having two or more (meth)acryloyl groups. adhesive sheet. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the photopolymerization initiator (C) contains a hydrogen abstraction type photopolymerization initiator (c1). The adhesive sheet according to any one of claims 1 to 5, wherein the antistatic agent (D) contains an antistatic agent that does not have a polymerizable group. The adhesive sheet according to any one of claims 1 to 6, wherein the adhesive composition [I] contains a silane coupling agent (E). Claims 1 to 7, wherein the content of the (meth)acrylate monomer (B) is 0.1 to 15 parts by mass based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). The adhesive sheet according to any one of the above. Any one of claims 1 to 8, wherein the content of the antistatic agent (D) is 0.1 to 30 parts by mass based on 100 parts by mass of the hydroxyl group-containing (meth)acrylic polymer (A). The adhesive sheet described in item 1. The adhesive sheet according to any one of claims 1 to 9, which has photocurability. The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, which is used for bonding constituent members of an image display device. A laminate for configuring an image display device, in which two image display device component members are laminated via the adhesive sheet according to any one of claims 1 to 11. A laminate for configuring an image display device, in which two image display device constituent members are laminated via a cured pressure-sensitive adhesive sheet obtained by curing the pressure-sensitive adhesive sheet according to any one of claims 1 to 11. An image display device configured using the laminate for configuring an image display device according to claim 12 or 13.