KR20240104101A - Adhesive composition, adhesive sheet, optical laminate, image display panel and image display device - Google Patents

Abstract

The provided adhesive composition contains a polymer (A) having a polyether structure as a main component, and further contains a conductive agent and a radical scavenger. When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition, the pressure-sensitive adhesive sheet has a surface resistance value of 1×10 ¹⁰ Ω/□ or less. In addition, the provided adhesive sheet is formed of an adhesive composition containing polymer (B) having a relative dielectric constant of 5.0 or more at a frequency of 100 kHz, and the formic acid content after heating at 105°C for 120 hours is 1000 ppm or less on a mass basis. do.

Description

Adhesive composition, adhesive sheet, optical laminate, image display panel and image display device

The present invention relates to pressure-sensitive adhesive compositions, pressure-sensitive adhesive sheets, optical laminates, image display panels, and image display devices.

Recently, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) are rapidly becoming popular. These various image display devices have a laminated structure of an optical laminated body including, for example, an image display cell such as a liquid crystal cell or an EL light emitting element, an optical film such as a polarizing plate, and an adhesive sheet. The adhesive sheet is mainly used for bonding between optical films included in an optical laminated body, or for bonding an image display cell and an optical laminated body. Patent Document 1 discloses an adhesive composition containing a (meth)acrylic polymer having a structural unit derived from a polar group-containing monomer such as 2-methoxyethyl acrylate, and an adhesive sheet formed from the adhesive composition.

Japanese Patent Publication No. 2013-32428

In an image display device, static electricity is generated during its manufacture, for example, when an optical laminate is bonded to an image display cell via an adhesive sheet, or during use, for example, when a user touches the image display device. If the image display device is charged by this static electricity, problems such as display defects may occur. When using an image display device in an environment where static electricity is particularly likely to occur, for example, inside a vehicle, where other electronic devices are present, an adhesive is used to sufficiently prevent display defects due to charging of the image display device. It is conceivable to adjust the surface resistance value of the adhesive sheet to a low value by mixing a conductive agent into the composition. However, if the mixing amount of the conductive agent is excessively large, the optical properties tend to deteriorate due to precipitation of the conductive agent and the durability of the adhesive sheet decreases when exposed to high temperature environments such as those expected inside vehicles in the summer. There is.

The purpose of the present invention is to provide a pressure-sensitive adhesive composition suitable for use in optical laminates in environments where high temperatures must be considered while achieving a low surface resistance value, and a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition.

The present invention,

Contains a polymer (A) having a polyether structure as a main component,

Further comprising a conductive agent and a radical scavenging agent,

When formed into a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet provides a pressure-sensitive adhesive composition having a surface resistance value of 1×10 ¹⁰ Ω/□ or less.

In this specification, the surface resistance value of the adhesive sheet is expressed by the measured value when the thickness of the adhesive sheet is 20 μm.

From a separate aspect, the present invention:

Contains a polymer (D) having a polyether structure as a main component,

Includes more challenges,

When the adhesive sheet is formed, the adhesive sheet provides a pressure-sensitive adhesive composition having a radical generation amount RG ₁₀ of 1.5 × 10 ¹⁴ pieces/g or less and a surface resistance value of 1 × 10 ¹⁰ Ω/□ or less.

However, RG ₁₀ is the amount of radicals generated by the adhesive sheet when heated at 105°C for 10 minutes, as evaluated by electron spin resonance method.

From a separate aspect, the present invention:

An adhesive sheet formed from the above-described adhesive composition is provided.

From a separate aspect, the present invention:

The adhesive sheet described above,

optical film

It provides an optical laminate comprising a.

From a separate aspect, the present invention:

An image display panel including the optical laminate described above is provided.

From a separate aspect, the present invention:

An image display device including the image display panel described above is provided.

From a separate aspect, the present invention:

It is an adhesive sheet formed of an adhesive composition containing polymer (B),

The relative dielectric constant of the polymer (B) at a frequency of 100 kHz is 5.0 or more,

After heating the pressure-sensitive adhesive sheet at 105° C. for 120 hours, the pressure-sensitive adhesive sheet contains 1000 ppm or less of formic acid by mass.

From a separate aspect, the present invention:

It is an optical laminate containing an adhesive sheet and an optical film,

The optical film is a polarizing plate including a polarizer,

After heating the optical laminate at 105° C. for 120 hours, the polarizer provides an optical laminate containing 70 ppm or less of formic acid by mass.

According to the present invention, while achieving a low surface resistance value, it is possible to provide a pressure-sensitive adhesive composition suitable for use in an optical laminate in an environment where high temperature must be considered, and a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition.

1 is a cross-sectional view schematically showing an example of the adhesive sheet of the present invention.
Figure 2 is a cross-sectional view schematically showing an example of the optical laminated body of the present invention.
Figure 3 is a cross-sectional view schematically showing an example of the optical laminated body of the present invention.
Figure 4 is a cross-sectional view schematically showing an example of the optical laminated body of the present invention.
Figure 5 is a cross-sectional view schematically showing an example of the optical laminated body of the present invention.
Figure 6 is a cross-sectional view schematically showing an example of the optical laminated body of the present invention.
Fig. 7 is a cross-sectional view schematically showing an example of the image display panel of the present invention.
Fig. 8 is a cross-sectional view schematically showing an example of the image display panel of the present invention.
Fig. 9 is a cross-sectional view schematically showing an example of the image display panel of the present invention.

Although the present invention will be described in detail below, the present invention is not limited to the following embodiments, and may be implemented with any modification without departing from the gist of the present invention.

(Embodiment 1)

[Adhesive composition]

The pressure-sensitive adhesive composition (I) of the present embodiment contains a polymer (A) having a polyether structure as a main component, and further contains a conductive agent. According to the present inventors' examination, the polyether structure in the polymer (A) can promote ionization of the conductive agent contained in the pressure-sensitive adhesive composition (I), and ionization of the conductive agent can occur in the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition. It may contribute to a decrease in surface resistance value.

Additionally, according to further examination, (i) when a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a polymer (A) having a polyether structure as a main component is used in an optical laminate, unnecessary coloring, especially redness, occurs after passing through a high-temperature environment. coloration tends to occur, (ii) coloration is often seen when a polarizing plate is included in an optical laminate, and (iii) coloration occurs due to the polyether structure due to high temperature. It has been revealed that the mechanism by which radicals move to the optical film and act on the polymer contained in the optical film is assumed. As an action of radicals on polymers, for example, polyenization of polyvinyl alcohol (PVA), a typical polymer contained in polarizers, can be considered. Polyenization of PVA is a phenomenon in which multiple carbon-carbon unsaturated bonds occur in the main chain of PVA and the conjugated structure is elongated. The elongation of the conjugated structure causes absorption in the visible light region and causes coloring (typically red). It is thought to represent. Polyenylation of PVA can be explained as a phenomenon in which the cross-linked structure with boric acid is lost due to hydrolysis caused by heat, exposing many of the terminal OH groups of PVA, and dehydration condensation reaction progresses between the exposed OH groups. Additionally, this dehydration condensation reaction is presumed to be a radical reaction. In addition, it is not limited to PVA in the polarizer, and it is believed that the progress of a radical reaction within the optical film at high temperature may cause changes in optical properties such as coloring to the optical film. Additionally, the radicals generated due to the polyether structure may include radicals generated through the involvement of other components (e.g., polymerization initiator, crosslinking agent, antioxidant, etc.) starting from the radical generated from the polyether structure.

The adhesive composition (I) further contains a radical scavenger. By using a radical scavenger, it is possible to limit the amount of radicals generated under high temperatures in the adhesive sheet formed from the adhesive composition (I). The adhesive composition (I), which has a limited amount of radical generation at high temperatures when used as an adhesive sheet, is suitable for use in an optical laminate in an environment where high temperatures must be considered.

When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition (I), the formed pressure-sensitive adhesive sheet has a surface resistance value of 1×10 ¹⁰ Ω/□ or less. The surface resistance value is 5×10 ⁹ Ω/□ or less, 1×10 ⁹ Ω/□ or less, 8×10 ⁸ Ω/□ or less, 6×10 ⁸ Ω/□ or less, 5×10 ⁸ Ω/□ or less, It may be 4×10 ⁸ Ω/□ or less, 3×10 ⁸ Ω/□ or less, and further 2×10 ⁸ Ω/□ or less. The lower limit of the surface resistance value is, for example, 1×10 ⁶ Ω/□ or more, and may be 1×10 ⁷ Ω/□ or more. The pressure-sensitive adhesive composition (I), which has a surface resistance value in the above range when used as a pressure-sensitive adhesive sheet, is suitable for use in environments where static electricity is likely to be generated, for example, inside a vehicle.

<Polymer (A)>

Examples of polymer (A) are (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. However, the polymer (A) is not limited to the above examples as long as it has a polyether structure. The polymer (A) is preferably a (meth)acrylic polymer. In other words, the adhesive composition (I) may contain a (meth)acrylic polymer as a main component. In other words, the adhesive composition (I) may be an acrylic adhesive composition. The main ingredient means the ingredient with the highest content in the composition. The content of the main component is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 75% by weight or more, and further 80% by weight or more. In this specification, (meth)acrylic polymer means a polymer having structural units derived from (meth)acrylic monomers such as (meth)acrylate. The content of structural units derived from (meth)acrylic monomers in the (meth)acrylic polymer is, for example, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, and 80% by weight or more. , it may be 85% by weight or more, 90% by weight or more, and further may be 95% by weight or more. The (meth)acrylic polymer may contain only structural units derived from (meth)acrylic monomers. (Meth)acrylic means acrylic and methacrylic. (meth)acrylate means acrylate and methacrylate.

Polymer (A) has a polyether structure. A polyether structure is a structure containing at least two ether groups (-O-). The polyether structure may be linear or may have branches. An example of a polyether structure includes an alkyl group that may be linear or may have branches, and at least two ether groups. The polymer (A) may have a polyether structure in the main chain or in the side chain, and it is preferable to have it in the side chain. The polymer (A) may be a (meth)acrylic polymer having a polyether structure in the side chain.

The polymer (A) may have a structural unit having a polyether structure. In the structural unit, the polyether structure may be located in the main chain or in the side chain, and is preferably located in the side chain. The polymer (A) may have a structural unit derived from a (meth)acrylic monomer having a polyether structure in the side chain.

An example of polymer (A) having a polyether structure in the side chain has a structural unit derived from a monomer shown in the following formula (1). R ¹ in formula (1) is a hydrogen atom or a methyl group. R ² in formula (1) is an alkyl group that may be linear or may have branches, and is preferably a linear alkyl group. Examples of R ² are methyl group and ethyl group. n is an integer of 1 to 15, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. When n is 1, the monomer of formula (1) includes “-O-” of the COO group and two ether groups. The monomer of formula (1) is a type of (meth)acrylic monomer, and more specifically, a type of (meth)acrylate monomer. Focusing on the R ² O group at the side chain terminal, the monomer of formula (1) is also a type of alkoxy group-containing (meth)acrylate monomer. The structural unit derived from the monomer of formula (1) has a polyether structure in the side chain.

Examples of monomers of formula (1) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxyethyl (meth)acrylate, They are toxytriethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate, and preferably 2-methoxyethyl acrylate (MEA). The structural unit derived from the monomer of formula (1) may particularly contribute to a decrease in the surface resistance value of the adhesive sheet formed from the adhesive composition (I).

The content of the structural unit having a polyether structure (for example, a structural unit derived from a monomer of formula (1)) in the polymer (A) is, for example, 15% by weight or more, 20% by weight or more, 25% by weight or more. % by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75 It may be % by weight or more, 80 % by weight or more, 85 % by weight or more, 90 % by weight or more, and further 95 % by weight or more. The upper limit of the content rate is, for example, 100% by weight or less, and may be 99.5% by weight or less, and further may be 99% by weight or less.

The polymer (A) may have one or two or more types of structural units derived from the following monomer (A2). In addition, the monomer (A2) shown below can be copolymerized with the monomer of formula (1).

An example of the monomer (A2) is a (meth)acrylic monomer having an alkyl group of 1 to 30 carbon atoms in the side chain. The alkyl group may be linear or may have branches. Examples of (meth)acrylic monomers having an alkyl group in the side chain include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and n-butyl (meth)acrylate. Latex, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate ) Acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate and octadecyl (meth)acrylate. It's a rate. The content of the structural unit derived from a (meth)acrylic monomer having an alkyl group in the side chain in the polymer (A) is, for example, 80% by weight or less, 70% by weight or less, 60% by weight or less, 50% by weight or less, It may be 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, and further may be 5% by weight or less, or 0% by weight (it does not need to have the structural unit).

Another example of monomer (A2) is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a hydroxyl group-containing (meth)acrylic monomer. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. , hydroxyalkyl (meth)acrylates such as 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, and (4-hydride) Roxymethylcyclohexyl)-methyl acrylate. From the viewpoint of improving the durability of the adhesive sheet formed from the adhesive composition (I), 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable, and 4-hydroxybutyl (meth)acrylate is preferred. Acrylates are more preferred. The content of the structural unit derived from the hydroxyl-containing monomer in the polymer (A) is, for example, 1 to 5% by weight, and may be 3% by weight or less, and further may be 2% by weight or less. The polymer (A) does not need to have structural units derived from hydroxyl group-containing monomers.

The monomer (A2) may be an aromatic ring-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, or an amide group-containing monomer. The aromatic ring-containing monomer may be an aromatic ring-containing (meth)acrylic monomer. Examples of aromatic ring-containing monomers include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and ethylene oxide-modified nonylphenol (meth)acrylate. ester, hydroxyethylated β-naphthol (meth)acrylate and biphenyl (meth)acrylate. Examples of carboxyl group-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of amino group-containing monomers are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide group-containing monomers include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, and N-methyl(meth)acrylamide. Acrylamide, N-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylol-N-propane (meth)acrylamide, aminomethyl (meth) Acrylamide-based monomers such as acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, and mercaptoethyl (meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

The monomer (A2) may be a polyfunctional monomer. Examples of polyfunctional monomers include hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and neopentyl. Glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetramethylolmethane tri(meth)acrylate, multifunctional acrylates such as allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; And it is divinylbenzene. Multifunctional acrylates are preferably 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate.

The total content of structural units derived from aromatic ring-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, and polyfunctional monomers in the polymer (A) is preferably 20% by weight or less, and more preferably It is preferably 10% by weight or less, more preferably 8% by weight or less. When the polymer (A) has the structural unit, the total content is, for example, 0.01% by weight or more, and may be 1% by weight or more, 2% by weight or more, and even 3% by weight or more. The polymer (A) does not need to have these structural units. In particular, in the polymer (A), the content of the structural unit derived from the carboxyl group-containing monomer may be less than 0.1% by weight or 0% by weight (without the structural unit).

Examples of other monomers (A2) include nitrile group-containing (meth)acrylates such as (meth)acrylonitrile; Epoxy group-containing monomers such as glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate; monomers containing sulfonic acid groups such as sodium vinyl sulfonate; Monomers containing phosphate groups; (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; Vinyl esters such as vinyl acetate and vinyl propionate; Aromatic vinyl compounds such as styrene and vinyl toluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, and isobutylene; Vinyl ethers such as vinyl alkyl ether; And it is vinyl chloride.

The total content of structural units derived from the above-mentioned other monomer (A2) in the polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, or 0% by weight (the structural unit is (not having) is preferable.

The polymer (A) can be formed by polymerizing one or two or more types of monomers described above by a known method. You may polymerize a monomer and a partially polymerized product of the monomer. Polymerization can be performed, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of forming a pressure-sensitive adhesive sheet with excellent optical transparency, solution polymerization and active energy ray polymerization are preferable. Polymerization is preferably carried out avoiding contact between the monomer and/or partial polymer and oxygen. For this reason, for example, polymerization is performed in an inert gas atmosphere such as nitrogen, or in a state where oxygen is blocked by a resin film, etc. Polymerization can be employed. The polymer (A) to be formed may be any of random copolymers, block copolymers, graft copolymers, etc.

The polymerization system forming the polymer (A) may contain one or two or more types of polymerization initiators. The type of polymerization initiator can be selected by polymerization reaction, and may be, for example, a thermal polymerization initiator or a photopolymerization initiator.

Solvents used in solution polymerization include, for example, esters such as ethyl acetate and n-butyl acetate; Aromatic hydrocarbons such as toluene and benzene; Aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

Polymerization initiators used in solution polymerization include, for example, azo-based polymerization initiators, peroxide-based polymerization initiators, and redox-based polymerization initiators. Peroxide-based polymerization initiators include, for example, dibenzoyl peroxide and t-butyl permaleate. Among them, the azo-based polymerization initiator disclosed in Japanese Patent Application Laid-Open No. 2002-69411 is preferable. The azo-based polymerization initiator is, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2- Methyl propionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, and may be 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total amount of monomers.

Active energy rays used in active energy ray polymerization include, for example, ionizing radiation such as α-rays, β-rays, γ-rays, neutron beams, and electron beams, and ultraviolet rays. As for the active energy ray, ultraviolet rays are preferable. Polymerization by irradiation of ultraviolet rays is also called photopolymerization. The polymerization system of active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for active energy polymerization are not limited as long as polymer (A) is formed.

Photopolymerization initiators include, for example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, and benzyl-based photopolymerization. Initiator, benzophenone-based photopolymerization initiator, ketal-based photopolymerization initiator, and thioxanthone-based photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

Benzoin ether-based photopolymerization initiators include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-di. Phenylethan-1-one, anisole methyl ether. Acetophenone-based photopolymerization initiators include, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, 4 -(t-Butyl)dichloroacetophenone. The α-ketol-based photopolymerization initiator is, for example, 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. The aromatic sulfonyl chloride-based photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. A photoactive oxime-based photopolymerization initiator is, for example, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. The benzoin-based photopolymerization initiator is, for example, benzoin. The benzyl-based photopolymerization initiator is, for example, benzyl. Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. The ketal-based photopolymerization initiator is, for example, benzyldimethyl ketal. Thioxanthone-based photopolymerization initiators include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and 2,4-diiso Propylthioxanthone and dodecylthioxanthone.

The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 parts by weight, based on 100 parts by weight of the total amount of monomers.

The weight average molecular weight (Mw) of the polymer (A) is, for example, 1 million to 3 million, and preferably 1.8 million to 3 million. When the weight average molecular weight of the polymer (A) is 1 million to 3 million, cracking of the adhesive sheet can be suppressed and the increase in viscosity and occurrence of gelation tend to be suppressed. The weight average molecular weight (Mw) of the polymer in this specification is a value (polystyrene conversion) based on measurement by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the polymer (A) is, for example, -50°C or lower, preferably -52°C or lower, and more preferably -55°C or lower. The lower limit of Tg of polymer (A) is, for example, -75°C. The Tg of the polymer (A) is a value obtained by calculating the Tg of each monomer forming a structural unit of the polymer (A) as a homopolymer and averaging these Tgs in consideration of the content of the structural units.

The content of polymer (A) in the adhesive composition (I) is, in terms of solids ratio, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 75% by weight or more, and further 80% by weight or more. . The upper limit of the content rate is, for example, 99% by weight or less, and may be 97% by weight or less, and may also be 95% by weight or less.

<Challenge>

The adhesive composition (I) further contains a conductive agent (antistatic agent). The adhesive composition (I) may contain one type or two or more types of conductive agents. Examples of conductive agents are ionic compounds such as salts. The ionic compound may be an ionic liquid that is liquid at room temperature (25°C).

Examples of ionic compounds are inorganic cationic salts and organic cationic salts. An example of an inorganic cationic salt is an inorganic cation-anion salt. An example of a cation contained in an inorganic cation salt is an alkali metal ion. The alkali metal ion is, for example, lithium ion, sodium ion, or potassium ion, and is preferably lithium ion. The inorganic cationic salt may be a lithium salt.

Examples of anions included in inorganic cation salts are Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CF ₃ COO ^- , CH ₃ SO ₃ ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₃ C ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , (CN) ₂ N ^- , C ₄ F ₉ SO ₃ ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , -O ₃ S(CF ₂ ) ₃ SO ₃ ^- and the following general formulas (a) to It is an anion represented by (d).

(a)(C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10)

(b) CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10)

(c) -O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer from 1 to 10)

(d)(C _p F _2p+1 SO ₂ )N ^- (C _q F _2q+1 SO ₂ ) (p and q are independently integers of 1 to 10)

The anion contained in the inorganic cation salt is preferably a fluorine-containing anion, and more preferably a fluorine-containing imide anion. An example of a fluorine-containing imide anion is an imide anion having a perfluoroalkyl group. A more specific example of the fluorine-containing imide anion is (CF ₃ SO ₂ )(CF ₃ CO)N ^- or an anion represented by the above general formula (a), (b) or (d), preferably It is a (perfluoroalkylsulfonyl)imide represented by general formula (a) such as (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , and more preferably (CF ₃ It is bis(trifluoromethanesulfonyl)imide expressed as SO ₂ ) ₂ N ^- . An example of a preferred inorganic cationic salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

An example of an organic cation salt is an organic cation-anion salt. An example of a cation contained in an organic cation salt is an organic onium containing an organic group. Examples of oniums contained in organic oniums are nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium, and nitrogen-containing onium and sulfur-containing onium are preferable. Examples of nitrogen-containing oniums include ammonium cation, piperidinium cation, pyrrolidinium cation, pyridinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, di Hydropyrimidinium cation, pyrazolium cation, and pyrazolinium cation. An example of a sulfur-containing onium is the sulfonium cation. An example of a phosphorus containing onium is the phosphonium cation. Examples of organic groups contained in organic onium are alkyl group, alkoxyl group, and alkenyl group. Specific examples of preferred organic oniums are tetraalkylammonium cations (e.g., tributylmethylammonium cation), alkylpiperidinium cations, and alkylpyrrolidinium cations.

Examples of anions contained in organic cation salts are the same as those of anions contained in inorganic cation salts. Examples of preferred organic cationic salts are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

The conductive agent may be used in combination of an inorganic cation salt and an organic cation salt.

The mixing amount of the conductive agent in the adhesive composition (I) is, for example, 0.5 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, and further 4 parts by weight, based on 100 parts by weight of the polymer (A). It may be more than parts by weight. The upper limit of the mixing amount is, for example, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, less than 10 parts by weight, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, with respect to 100 parts by weight of polymer (A). It may be less than or equal to 6 parts by weight.

<Radical capture agent>

The adhesive composition (I) further contains a radical scavenger. Examples of radical scavengers include various antioxidants such as hindered phenol-based, hindered amine-based, phosphite-based, phenol-based and thioether-based, and blends of these types.

Types of antioxidants include, for example, radical chain inhibitors and peroxide decomposition agents.

The antioxidant may be at least one selected from hindered phenol-based, hindered amine-based, and phosphite-based.

The hindered phenolic antioxidant may have a structure in which a tert-butyl group is bonded to at least one carbon atom adjacent to the carbon atom on the aromatic ring to which the OH group of phenol is bonded. Examples of hindered phenolic antioxidants include dibutylhydroxytoluene (BHT); And Irganox1010, Irganox1010FF, Irganox1035, Irganox1035FF, Irganox1076, Irganox1076FD, Irganox1076DWJ, Irganox1098, Irganox1135, Irganox1330, Irganox1726, Irganox1425WL, Irganox15 20L, Irganox245, Irganox245FF, Irganox259, Irganox3114, Irganox565, and Irganox295 (all are brand names, manufactured by BASF).

The hindered amine-based antioxidant may have at least one hindered piperidine group per molecule. Examples of hindered amine-based antioxidants are Adekastep LA-63, Adekastep LA-63P, Adekastep LA-52, and Adekastep LA-57 (all are brand names, manufactured by ADEKA).

Examples of phosphite-based antioxidants include triphenylphosphite, diphenylisodecylphosphite, and phenyldiisodecylphosphite; And Adeka Step 2112, Adeka Step 2112RG, Adeka Step 1178, and Adeka Step 3010 (all are brand names, manufactured by ADEKA).

Examples of phenol-based antioxidants are monophenol-based antioxidants, bisphenol-based antioxidants, and high molecular weight phenolic antioxidants. Examples of monophenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearin-β-( It is 3,5-di-t-butyl-4-hydroxyphenyl)propionate. Examples of bisphenol-based antioxidants include 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4, 4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 3,9-bis[1,1- Dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane. Examples of high molecular weight phenolic antioxidants include 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6- Tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propio Nate] methane, bis [3,3'-bis-(4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3',5'-di-t -Butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione and tocophenol.

Examples of thioether-based antioxidants are Adekastep AO-503 and Adekastep AO-26 (both brand names, manufactured by ADEKA).

The molecular weight of the radical scavenger (for example, antioxidant) may be 1000 or less, 900 or less, 850 or less, 800 or less, 700 or less, 600 or less, 500 or less, 450 or less, and further 400 or less. The lower limit of molecular weight is, for example, 100 or more. According to the studies of the present inventors, the radical scavenger whose molecular weight is within the above range is particularly suitable for suppressing the amount of radicals generated in the adhesive sheet formed from the adhesive composition (I).

The radical scavenger (for example, antioxidant) may be liquid at room temperature (25°C).

The compounding amount of the radical scavenger in the adhesive composition (I) is, for example, 0.1 part by weight or more, 0.2 part by weight or more, 0.3 part by weight or more, 0.4 part by weight or more, and further, with respect to 100 parts by weight of the polymer (A). It may be 0.5 parts by weight or more. The upper limit of the mixing amount is, for example, 15 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, 5 parts by weight or less, less than 5 parts by weight, 4 parts by weight or less, 3 with respect to 100 parts by weight of polymer (A). It may be less than or equal to 2 parts by weight.

<Additives>

The adhesive composition (I) may further contain materials other than the polymer (A), the conductive agent, and the radical scavenger. Examples of such materials are additives. Examples of additives include crosslinking agents, silane coupling agents, colorants such as pigments and dyes, ultraviolet absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, softeners, polymerization inhibitors, rust inhibitors, and inorganic fillers. , organic fillers, metal powders, etc., powders, particles, and thin matter. The additives can be blended in a total amount of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 3 parts by weight or less, based on 100 parts by weight of the polymer (A).

Examples of crosslinking agents are organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Organic crosslinking agents and multifunctional metal chelates can be used for either solvent-based or active energy ray-curable adhesive composition (I). When the adhesive composition (I) is a solvent type, the crosslinking agent is preferably a peroxide-based crosslinking agent or an isocyanate-based crosslinking agent. A peroxide-based crosslinking agent and an isocyanate-based crosslinking agent may be used together. The adhesive composition (I) may contain an isocyanate-based crosslinking agent, may contain a peroxide-based crosslinking agent, or may contain both an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent.

Examples of the isocyanate-based crosslinking agent include aromatic isocyanate compounds such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and polymethylene polyphenylisocyanate; Alicyclic isocyanate compounds such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and isophorone diisocyanate; These are aliphatic isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. Isocyanate-based crosslinking agents include compounds obtained by adding the above isocyanate compound to a polyhydric alcohol compound such as trimethylolpropane (adduct body); Compounds obtained by addition reaction of the above isocyanate compound with polyols such as polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, and polyisoprene polyol; Derivatives of the above isocyanate compounds, such as isocyanurate compounds, may be used. Specific examples of derivatives include trimethylolpropane/tolylene diisocyanate terpolymer adduct (e.g., Tosoh Corporation, Coronate L), trimethylolpropane/hexamethylene diisocyanate terpolymer adduct (e.g., Tosoh Co., Ltd.) manufactured by Coronate HL), and an isocyanurate form of hexamethylene diisocyanate (e.g., Coronate HX manufactured by Tosoh Corporation).

When the pressure-sensitive adhesive composition (I) contains an isocyanate-based crosslinking agent, the compounding amount is, for example, 0.1 to 10 parts by weight, 0.2 to 5 parts by weight, 0.25 to 3 parts by weight, based on 100 parts by weight of polymer (A). 0.3 to 1 part by weight, or even 0.3 to 0.5 parts by weight, may be added.

Examples of peroxide-based crosslinking agents include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, and t-butyl. Peroxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxide These are oxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, and 1,1-di(t-hexylperoxy)cyclohexane. The peroxide-based crosslinking agent may be benzoyl peroxide because it has excellent crosslinking reaction efficiency.

When the pressure-sensitive adhesive composition (I) contains a peroxide-based crosslinking agent, the blending amount thereof is, for example, 0.005 to 5 parts by weight, 0.01 to 3 parts by weight, 0.05 to 2 parts by weight, based on 100 parts by weight of polymer (A). It may be added in an amount of 0.07 to 1 part by weight, 0.07 to 0.5 part by weight, 0.07 to 0.3 part by weight, and further 0.07 to 0.2 part by weight.

Examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl) ) Silane coupling agents containing epoxy groups such as ethyltrimethoxysilane; 3-Aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N -Amino group-containing silane coupling agents such as phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; 3-Isocyanate is a silane coupling agent containing an isocyanate group such as propyltriethoxysilane.

When the adhesive composition (I) contains a silane coupling agent, the compounding amount thereof is, for example, 5 parts by weight or less, 3 parts by weight or less, 1 part by weight or less, and 0.5 parts by weight, based on 100 parts by weight of the polymer (A). Hereinafter, it may be 0.2 part by weight or less, 0.1 part by weight or less, and further 0.05 part by weight or less. The adhesive composition (I) does not need to contain a silane coupling agent.

Types of the adhesive composition (I) include, for example, emulsion type, solvent type (solution type), active energy ray curing type (photocuring type), and heat melt type (hot melt type). From the viewpoint of being able to form a highly durable adhesive sheet, the adhesive composition (I) may be of a solvent type or an active energy ray curable type, or may be of a solvent type. The solvent-type adhesive composition (I) does not need to contain a photocuring agent such as an ultraviolet curing agent.

The adhesive composition (I) can be used, for example, in an optical laminate. In other words, the adhesive composition (I) may be used for an optical laminate. However, the use of the adhesive composition (I) is not limited to the above examples.

(Embodiment 2)

[Adhesive composition]

Adhesive composition (II) of this embodiment contains polymer (B). The adhesive composition (II) may contain polymer (B) as a main component. “Main component” has the meaning described above. Here, the relative dielectric constant of polymer (B) at a frequency of 100 kHz is 5.0 or more. Additionally, after heating the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (II) at 105° C. for 120 hours, the pressure-sensitive adhesive sheet contains 1000 ppm or less of formic acid on a mass basis. When the formic acid content is this low, coloring is unlikely to occur in the optical laminate even after passing through a high temperature environment.

According to the present inventors' examination, (iv) when an adhesive sheet formed from an adhesive composition containing a polymer having a relative dielectric constant at a frequency of 100 kHz of 5.0 or more is used in an optical laminate, unnecessary coloring, especially redness, occurs after passing through a high temperature environment. It has been found that coloring of (v) tends to occur, and that (v) coloring is often visible when a polarizing plate is included in an optical laminate. As a cause of this, it was found that, for example, the acid contained in the adhesive sheet acts on the polymer contained in the optical film. Additionally, the present inventors discovered that the acid that acts on the polymer contained in the optical film is formic acid. As for the action of formic acid on the polymer, for example, polyenization of PVA contained in the polarizer can be considered. In PVA, it is assumed that the exposed OH group is protonated by formic acid, and a dehydration condensation reaction proceeds. In addition, it is not limited to PVA in the polarizer, and it is thought that the progress of the above reaction with formic acid in the optical film at high temperature may cause changes in optical properties such as coloring to the optical film.

As described above, by heating the optical laminate, formic acid may be generated in the members constituting the optical laminate. Members of the optical laminate in which formic acid may be generated include adhesive sheets, polarizing plates, OCA (optical clear adhesive) layers, and protective films. The OCA layer is, for example, an adhesive layer formed on the surface of the polarizing plate opposite to the adhesive sheet in the optical laminate. In other words, the polarizing plate may be disposed between the adhesive sheet and the OCA layer. The OCA layer is a layer containing an optically transparent adhesive. The material of the adhesive contained in the OCA layer is not particularly limited and includes, for example, (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine polymer, rubber polymer, etc. as the base polymer. do. A protective film is, for example, a film formed on the surface of a polarizer. Details of the protective film will be described later. For example, formic acid may be generated as the protective film hydrolyzes.

After heating the adhesive sheet formed from the adhesive composition (II) at 105°C for 120 hours, the content of formic acid contained in the adhesive sheet is, on a mass basis, 800 ppm or less, 500 ppm or less, 200 ppm or less, 100 ppm or less, 70 ppm or less, and 50 ppm or less. , 25 ppm or less, 5 ppm or less, 2.5 ppm or less, and may even be less than 2.5 ppm. The lower limit of the content of formic acid is not particularly limited, and is, for example, 0 ppm or more on a mass basis.

The relative dielectric constant P of polymer (B) at a frequency of 100 kHz is 5.0 or more. When the relative dielectric constant P is this high, there is a tendency to suppress a decrease in the sensitivity of the touch sensor provided in the image display device even when an optical film with a low relative dielectric constant, especially a polarizing film and an adhesive sheet are used in combination.

The relative dielectric constant P can be measured by the following method. First, a test piece consisting of only polymer and having a thickness of 30 μm is produced. For this test piece, the relative dielectric constant at a frequency of 100 kHz is measured by the automatic balance bridge method (transformer bridge method) in accordance with JIS K6911: 1995. The obtained measured value can be regarded as the relative permittivity P. The details of the relative dielectric constant measurement conditions are as follows.

·Measuring conditions

Measurement method: Capacitance method (device: 4294A Precision Impedance Analyzer manufactured by Agilent Technologies)

Electrode composition: aluminum plate with a diameter of 12.1 mm and a thickness of 0.5 mm.

Counter electrode: 3oz copper plate

Measurement environment: 23±1℃, 52±1%RH

The relative dielectric constant P may be 6.0 or more, 6.5 or more, 6.8 or more, 7.0 or more, 7.3 or more, and further 7.5 or more. The upper limit of relative dielectric constant P is not particularly limited, and is, for example, 10.0 or less.

The polymer (B) contained in the adhesive composition (II) may be, for example, the polymer (A) described in Embodiment 1.

The adhesive composition (II) may further contain a radical scavenger and a peroxide-based crosslinking agent.

The radical scavenger may be an antioxidant. As a radical scavenger, for example, the radical scavenger described in Embodiment 1, that is, various antioxidants, can be used. In the adhesive composition (II), the molecular weight of the radical scavenger (for example, antioxidant) may be 1000 or more. The upper limit of molecular weight is, for example, 1500 or less. According to the examination by the present inventors, the radical scavenger whose molecular weight is in the above range is particularly suitable for suppressing the amount of formic acid generated in the adhesive sheet formed from the adhesive composition (II). The preferred blending amount of the radical scavenger in the adhesive composition (II) is as described in Embodiment 1.

As the peroxide-based crosslinking agent, for example, the peroxide-based crosslinking agent described in Embodiment 1 can be used. The preferred blending amount of the peroxide-based crosslinking agent in the pressure-sensitive adhesive composition (II) is as described in Embodiment 1. Excessive mixing of a peroxide-based crosslinking agent may promote polyenylation of PVA contained in the polarizer. In polyenization, there is a possibility that a reactant of a reaction involving a peroxide-based crosslinking agent, for example, benzoic acid, is involved. When the pressure-sensitive adhesive composition (II) contains a peroxide-based crosslinking agent, it is particularly suitable for suppressing coloring if the compounding amount is within the above range.

The adhesive composition (II) may further contain an isocyanate-based crosslinking agent in addition to the peroxide-based crosslinking agent. Examples of the isocyanate-based crosslinking agent are as described in Embodiment 1. The preferred blending amount of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition (II) is also the same as described in Embodiment 1.

The adhesive composition (II) may further contain materials other than the polymer (B), a radical scavenger, and a peroxide-based crosslinking agent. An example of this material is a conductive agent (antistatic agent). The adhesive composition (II) may contain one type or two or more types of conductive agents. Examples of conductive agents are ionic compounds such as salts. The ionic compound may be an ionic liquid that is liquid at room temperature (25°C). As a conductive agent, the conductive agent described in Embodiment 1 can be used. Examples of conductive agents are ionic compounds such as salts. Examples of ionic compounds are inorganic cationic salts and organic cationic salts. The conductive agent may contain an organic cation salt. The conductive agent may be an organic cation salt. The mixing amount of the conductive agent in the adhesive composition (II) is the same as described in Embodiment 1.

The adhesive composition (II) may further contain materials other than the polymer (B), a radical scavenger, a peroxide-based crosslinking agent, and a conductive agent. Examples of such materials are additives. Examples of additives are as described in Embodiment 1.

Types of the adhesive composition (II) include, for example, emulsion type, solvent type (solution type), active energy ray curing type (photocuring type), and heat melt type (hot melt type). From the viewpoint of being able to form a highly durable adhesive sheet, the adhesive composition (II) may be a solvent type or an active energy ray curable type, or may be a solvent type. The solvent-type adhesive composition (II) does not need to contain a photocuring agent such as an ultraviolet curing agent.

Adhesive composition (II) can be used, for example, in an optical laminate. In other words, the adhesive composition (II) may be used for an optical laminate. However, the use of the adhesive composition (II) is not limited to the above examples.

Additionally, after heating the adhesive sheet formed from the adhesive composition (II), the content of acetic acid contained in the adhesive sheet may be low. After heating the adhesive sheet formed from the adhesive composition (II) at 105°C for 120 hours, the adhesive sheet may contain 50 ppm or less of acetic acid on a mass basis. When the acetic acid content is this low, coloring is less likely to occur in the optical laminate even after passing through a high temperature environment.

After heating the adhesive sheet formed from the adhesive composition (II) at 105°C for 120 hours, the content of acetic acid contained in the adhesive sheet is, on a mass basis, 30 ppm or less, 20 ppm or less, 15 ppm or less, 10 ppm or less, 7 ppm or less, 5 ppm or less. , 3 ppm or less, 2.8 ppm or less, and further may be less than 2.5 ppm. The lower limit of the acetic acid content is not particularly limited, and is, for example, 0 ppm or more on a mass basis.

(Embodiment 3)

[Adhesive composition]

The pressure-sensitive adhesive composition (III) of the present embodiment contains a polymer (D) having a polyether structure as a main component, and further contains a conductive agent. According to the present inventors' examination, the polyether structure in the polymer (D) can promote the ionization of the conductive agent contained in the pressure-sensitive adhesive composition (III), and the ionization of the conductive agent is caused by the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition. It may contribute to a decrease in surface resistance value.

Furthermore, according to further examination, when a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing (vi) a polymer (D) having a polyether structure as a main component is used in an optical laminate, unnecessary coloring, especially redness, occurs after passing through a high-temperature environment. coloration tends to occur, (vii) coloration is often seen when a polarizing plate is included in an optical laminate, and (viii) coloration occurs due to the polyether structure due to high temperature. It has been revealed that the mechanism by which radicals move to the optical film and act on the polymer contained in the optical film is assumed. As an action of radicals on polymers, for example, polyenization of polyvinyl alcohol (PVA), a typical polymer contained in polarizers, can be considered. Polyenization of PVA is a phenomenon in which multiple carbon-carbon unsaturated bonds occur in the main chain of PVA and the conjugated structure is elongated. The elongation of the conjugated structure causes absorption in the visible light region and causes coloring (typically red). It is thought to represent. Polyenylation of PVA can be explained as a phenomenon in which the cross-linked structure with boric acid is lost due to hydrolysis caused by heat, exposing many of the terminal OH groups of PVA, and dehydration condensation reaction progresses between the exposed OH groups. Additionally, it is assumed that this dehydration condensation reaction is a radical reaction. In addition, it is not limited to PVA in the polarizer, and it is believed that the progress of a radical reaction within the optical film at high temperature may cause changes in optical properties such as coloring to the optical film. Additionally, the radicals generated due to the polyether structure may include radicals generated through the involvement of other components (e.g., polymerization initiator, crosslinking agent, antioxidant, etc.) starting from the radical generated from the polyether structure.

When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition (III), the amount of radicals generated RG ₁₀ in the formed pressure-sensitive adhesive sheet is limited to 1.5 × 10 ¹⁴ /g or less. However, the radical generation amount RG ₁₀ is the radical generation amount of the adhesive sheet when heated at 105°C for 10 minutes, as evaluated by electron spin resonance method (hereinafter referred to as ESR). The adhesive composition (III), which has a limited amount of radical generation at high temperatures when used as an adhesive sheet, is suitable for use in an optical laminate in an environment where high temperatures must be considered.

The amount of radicals generated RG ₁₀ may be 1.3×10 ¹⁴ pieces/g or less, 1.0×10 ¹⁴ pieces/g or less, 9.0×10 ¹³ pieces/g or less, and may also be 8.0×10 ¹³ pieces/g or less. The lower limit of the amount of radicals generated RG ₁₀ is not limited, but is, for example, 1.0 × 10 ¹⁰ /g or more.

When an adhesive sheet is formed from the adhesive composition (III), the amount of radicals generated RG ₂₀ in the formed adhesive sheet is, for example, 2.5 × 10 ¹⁴ /g or less, 2.0 × 10 ¹⁴ or less / g, 1.5 × 10 ¹⁴ It may be 1.2×10 ¹⁴ pieces/g or less, and even 1.0×10 ¹⁴ pieces/g or less. The lower limit of the amount of radicals generated RG ₂₀ is not limited, but is, for example, 1.0 × 10 ¹⁰ /g or more. However, the radical generation amount RG ₂₀ is the radical generation amount of the adhesive sheet when heated at 105°C for 20 minutes, as evaluated by ESR. The adhesive composition (III) having a radical generation amount RG ₂₀ in the above range when used as an adhesive sheet is particularly suitable for use in an optical laminate in an environment where high temperature must be considered.

The ratio of RG ₂₀ to the radical generation amount RG ₁₀ (radical generation amount ratio RG ₂₀ /RG ₁₀ ) is, for example, 1.7 or less, and may be 1.5 or less, less than 1.5, 1.4 or less, less than 1.4, and further 1.3 or less. The lower limit of RG ₂₀ /RG ₁₀ is, for example, 0.8 or more. The pressure-sensitive adhesive composition (III), which has RG ₂₀ /RG ₁₀ in the above range when used as a pressure-sensitive adhesive sheet, is particularly suitable for use in an optical laminate in an environment where high temperature must be considered.

When a pressure ^- sensitive adhesive sheet is ^formed from the pressure-sensitive adhesive composition (III), the amount of radicals generated RG ₃₀ in the formed pressure-sensitive adhesive sheet ^is , for example, 3.0 pcs/g or less, 1.7×10 ¹⁴ pcs/g or less, 1.5×10 ¹⁴ pcs/g or less, 1.4×10 ¹⁴ pcs/g or less, 1.3×10 ¹⁴ pcs/g or less, further 1.2×10 ¹⁴ pcs/g or less It's okay. The lower limit of the amount of radicals generated RG ₃₀ is not limited, but is, for example, 1.0 × 10 ¹⁰ /g or more. However, the amount of radicals generated RG ₃₀ is the amount of radicals generated by the adhesive sheet when heated at 105°C for 30 minutes, as evaluated by ESR. The adhesive composition (I) whose radical generation amount RG ₃₀ when used as an adhesive sheet is within the above range is particularly suitable for use in an optical laminate in an environment where high temperature must be considered.

The ratio of RG ₃₀ to the radical generation amount RG ₁₀ (radical generation amount ratio RG ₃₀ /RG ₁₀ ) is, for example, 2.2 or less, and may be 2.0 or less, 1.9 or less, less than 1.9, 1.7 or less, 1.6 or less, and further 1.5 or less. The lower limit of RG ₃₀ /RG ₁₀ is, for example, 0.8 or more. The adhesive composition (I) having RG ₃₀ /RG ₁₀ in the above range when used as an adhesive sheet is particularly suitable for use in an optical laminate in an environment where high temperature must be considered.

The amount of radicals generated for the adhesive composition (III) can be evaluated as follows. First, a portion of the adhesive sheet formed of the adhesive composition to be evaluated is collected, filled into the tip of the ESR sample tube, and the sample tube is sealed. The amount of the above portion contained in the sample tube is approximately 50 mg. When the pressure-sensitive adhesive composition is in a state before forming the pressure-sensitive adhesive sheet (as an example, in a solution state), for example, a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition based on the pressure-sensitive adhesive sheet production method described later, and a portion of the formed pressure-sensitive adhesive sheet is taken. do. Next, the sample tube was set in the ESR device, the temperature was raised from room temperature (25 ± 5°C) to 105°C at a temperature increase rate of 30°C/min, and the temperature was increased for 10 minutes, 20 minutes, and 30 minutes based on the time when 105°C was reached. ESR measurements are performed after each minute has elapsed. From the signal intensity of the ESR signal observed by measurement, the amount of radicals generated can be quantitatively calculated. The ESR signal corresponding to the generated radical can be selected based on the g value of the signal (center position of the signal) and the cleavage width. The ESR signal corresponding to the radical may be found by comparing it with a profile obtained by performing ESR measurement without heating. The ESR signal corresponding to the radical may be a signal of a radical generated by involvement of other components starting from the radical generated from the polyether structure. Among the ESR signals corresponding to radicals, the signal with the strongest intensity can be selected. Additionally, it is well known to those skilled in the art that quantitative evaluation of radicals contained in a substance is possible through ESR. The amount of radicals generated in the adhesive sheet (cured product of the adhesive composition) can also be evaluated in detail using a known method.

The amount of radicals generated in the adhesive composition is, for example, the composition of the adhesive composition, the composition and content rate of the polymer (D), the type and content rate of the conductive agent, and the types of materials blended in the adhesive composition other than the polymer (D) and the conductive agent. , content rate and combination, and the degree of curing of the adhesive sheet, etc. may vary. The degree of curing of the adhesive sheet, for example, in the case of the solvent-type adhesive composition (III), depends on the solid content concentration and viscosity of the solution containing the adhesive composition, the conditions for forming the coating film on the base film, the drying conditions for the coating film, Also, when the device (heating furnace, etc.) that dries the coating film is non-sealed, it may change depending on the temperature and humidity of the atmosphere in which the device is placed.

When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition (III), the formed pressure-sensitive adhesive sheet has a surface resistance value of 1×10 ¹⁰ Ω/□ or less. The surface resistance value is 5×10 ⁹ Ω/□ or less, 1×10 ⁹ Ω/□ or less, 8×10 ⁸ Ω/□ or less, 6×10 ⁸ Ω/□ or less, 5×10 ⁸ Ω/□ or less, It may be 4×10 ⁸ Ω/□ or less, 3×10 ⁸ Ω/□ or less, and further 2×10 ⁸ Ω/□ or less. The lower limit of the surface resistance value is, for example, 1×10 ⁶ Ω/□ or more, and may be 1×10 ⁷ Ω/□ or more. The adhesive composition (III), which has a surface resistance value in the above range when used as an adhesive sheet, is suitable for use in an environment where static electricity is likely to be generated, for example, inside a vehicle.

<Polymer (D)>

Examples of polymer (D) are (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. However, the polymer (D) is not limited to the above examples as long as it has a polyether structure. The polymer (D) is preferably a (meth)acrylic polymer. In other words, the adhesive composition (III) may contain a (meth)acrylic polymer as a main component. In other words, the adhesive composition (III) may be an acrylic adhesive composition. “Main component” has the meaning described above.

The polymer (D) may be the polymer (A) described in Embodiment 1.

<Challenge>

The adhesive composition (III) further contains a conductive agent (antistatic agent). The adhesive composition (III) may contain one type or two or more types of conductive agents. Examples of conductive agents are ionic compounds such as salts. The ionic compound may be an ionic liquid that is liquid at room temperature (25°C). The details of the conductive agent are the same as described in Embodiment 1.

<Additives>

The adhesive composition (III) may further contain materials other than the polymer (D) and the conductive agent. Examples of such materials are additives. Examples of additives include crosslinking agents, silane coupling agents, colorants such as pigments and dyes, ultraviolet absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework enhancers, softeners, antioxidants, anti-aging agents, and light stabilizers. , polymerization inhibitors, rust inhibitors, inorganic fillers, organic fillers, metal powders, etc., powders, particles and thin matter. The details of the additive are as described in Embodiment 1.

Types of the adhesive composition (III) include, for example, emulsion type, solvent type (solution type), active energy ray curing type (photocuring type), and heat melt type (hot melt type). From the viewpoint of being able to form a highly durable adhesive sheet, the adhesive composition (III) may be of a solvent type or an active energy ray curable type, or may be of a solvent type. The solvent-type adhesive composition (III) does not need to contain a photocuring agent such as an ultraviolet curing agent.

Adhesive composition (III) can be used, for example, in an optical laminate. In other words, the adhesive composition (III) may be used for an optical laminate. However, the use of the adhesive composition (III) is not limited to the above examples.

The adhesive sheet formed from the adhesive composition (III) may have a radical generation amount RG ₁₀ in the range described above. In addition, the adhesive sheet formed from the adhesive composition (III) may have at least one characteristic selected from the radical generation amount RG ₂₀ and RG ₃₀ in the above-mentioned range, and the radical generation amount ratio RG ₂₀ /RG ₁₀ and RG ₃₀ /RG ₁₀ . there is.

(Embodiment 4)

[Adhesive sheet]

An example of the adhesive sheet of this embodiment is shown in Fig. 1. The pressure-sensitive adhesive sheet 1 in FIG. 1 is a sheet formed from the pressure-sensitive adhesive composition (I), a sheet formed from the pressure-sensitive adhesive composition (II), or a sheet formed from the pressure-sensitive adhesive composition (III).

When the adhesive sheet (1) is formed from the adhesive composition (I), the adhesive sheet (1) may have a surface resistance value in the range described above in the description of the adhesive composition (I). When the adhesive sheet (1) is formed from the adhesive composition (II), the adhesive sheet may contain formic acid in the range described above in the description of the adhesive composition (II). When the adhesive sheet 1 is formed from the adhesive composition (III), the adhesive sheet 1 may have a radical generation amount RG ₁₀ in the range described above in the description of the adhesive composition (III). In addition, when the adhesive sheet 1 is formed from the adhesive composition (III), the adhesive sheet 1 has a radical generation amount RG ₂₀ and RG ₃₀ in the ranges described above in the description of the adhesive composition (III), and a radical generation amount ratio. It may have at least one characteristic selected from RG ₂₀ /RG ₁₀ and RG ₃₀ /RG ₁₀ .

The adhesive sheet 1 can be formed from the adhesive composition (I) or the adhesive composition (II) by the following method. Hereinafter, a method of forming the adhesive sheet (1) from the adhesive composition (I) will be described. However, in the case of the adhesive composition (II) and the adhesive composition (III), the adhesive sheet (1) can be formed by the same method. You can.

For the solvent type, for example, the adhesive composition (I) or a mixture of the adhesive composition (I) and the solvent is applied to a base film to form a coating film, and the formed coating film is dried to form the adhesive sheet 1. The pressure-sensitive adhesive composition (I) is thermally cured by heat during drying. For the active energy ray curing type (photocuring type), for example, monomers (groups) that become polymer (A) by polymerization, and, if necessary, mixtures of partially polymerized products of the monomers (groups), polymerization initiators, additives, and solvents. is applied to a base film, and the formed coating film is irradiated with active energy rays to form an adhesive sheet (1). Before irradiation with active energy rays, the coating film may be dried to remove the solvent. The base film may be a film (release liner) whose application surface has been subjected to a release treatment.

The adhesive sheet 1 formed on the base film can be transferred to any layer. In addition, the base film may be an optical film such as a polarizing plate, and in this case, an optical laminated body containing the adhesive sheet 1 and the optical film is obtained.

For application to the base film, a known method can be adopted. Application includes, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, extrusion by die coater, etc. It can be done by court.

For the solvent type, the drying temperature after application is, for example, 40 to 200°C. The drying time is, for example, 5 seconds to 20 minutes, and may be 5 seconds to 10 minutes, and may also be 10 seconds to 5 minutes. For the active energy ray curable type, the drying temperature and drying time when drying after application may be within the above range.

The composition and mixture applied to the base film preferably have a viscosity suitable for handling and coating. For this reason, for the active energy ray curable type, it is preferable that the mixture to be applied contains a partial polymerization of a monomer (group).

The thickness of the adhesive sheet 1 is, for example, 2 μm to 55 μm, and may be 2 μm to 30 μm, 5 μm to 25 μm, or further 10 μm to 20 μm.

The adhesive sheet 1 can be used, for example, in an optical laminate. In other words, the adhesive sheet 1 may be used for an optical laminate. However, the use of the adhesive sheet 1 is not limited to the above examples.

(Embodiment 5)

[Optical laminate]

An example of the optical laminated body of this embodiment is shown in FIG. 2. The optical laminate 10A in FIG. 2 includes an adhesive sheet 1 and an optical film. The optical film in FIG. 2 is a polarizing plate (2). The polarizing plate 2 includes a polarizer. The adhesive sheet 1 and the polarizing plate 2 are laminated on each other. The optical laminate 10A can be bonded to an object (for example, an image display panel) via the adhesive sheet 1. The optical laminate 10A can be used as an optical film with an adhesive sheet attached thereto, and more specifically, as a polarizing plate with an adhesive sheet attached thereto. Examples of optical films other than the polarizing plate 2 are retardation films and laminated films containing a polarizing plate and/or retardation films. The optical film may be a circularly polarizing plate. However, the optical film is not limited to the above examples. The optical film may contain a glass film.

<Polarizer>

The polarizing plate 2 is typically a laminate containing a polarizer and a protective film (transparent protective film). The protective film is disposed, for example, in contact with the main surface (surface with the largest area) of the polarizer. The polarizer may be disposed between two protective films. The optical laminated body 10A further includes a protective film, and the protective film may be disposed on at least one side of the polarizer.

The polarizer is not particularly limited, and for example, hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, iodine, dichroic dyes, etc. A product made by adsorbing a coloring material and stretching it uniaxially; and polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochloric acid-treated polyvinyl chloride. The polarizer typically consists of a polyvinyl alcohol-based film (the polyvinyl alcohol-based film includes an ethylene/vinyl acetate copolymer-based partially saponified film) and a dichroic substance such as iodine.

The thickness of the polarizer is not particularly limited, and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, and further 20 μm or less. The lower limit of the thickness of the polarizer is not particularly limited, and is, for example, 1 μm or more, and may be 5 μm or more, 10 μm or more, and further may be 15 μm or more. A thin polarizer (for example, 20 μm or less in thickness) has suppressed dimensional change and can contribute to improving the durability of the optical laminate, especially durability under high temperatures.

As a material for the protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and (meth)acrylic resins. , cyclic polyolefin resin (norbornene-based resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. The material of the protective film may be a thermosetting resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone, or an ultraviolet curable resin. When the polarizing plate 2 has two protective films, the materials of the two protective films may be the same or different from each other. For example, a protective film made of a thermoplastic resin may be bonded to one main surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet curable resin may be bonded to the other main surface of the polarizer. . The protective film may contain one or more arbitrary additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, discoloration inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc.

The moisture permeability of the protective film is not particularly limited and may be 200 g/(m ² ·day) or less or 50 g/(m ² ·day) or less. In this case, it is possible to suppress moisture in the air from entering the inside of the polarizing plate 2, and the change in moisture content of the polarizing plate 2 can be suppressed. Accordingly, it is possible to suppress the occurrence of curl or dimensional change in the polarizing plate 2 during storage, etc. Additionally, when a protective film whose moisture permeability is limited to the above range is disposed between the adhesive sheet 1 and a polarizer, it may contribute to inhibiting the movement of radicals from the adhesive sheet 1 under high temperature. Materials that form a protective film with low moisture permeability include, for example, polyester-based polymers, polycarbonate-based polymers, arylate-based polymers, amide-based polymers, olefin-based polymers, cyclic olefin-based polymers, (meth)acrylic-based polymers, and A mixture of these may be mentioned.

The moisture permeability of the protective film can be measured by the following method in accordance with the moisture permeability test (cup method) of JIS Z0208: 1976. First, cut the protective film to a diameter of 60 mm and prepare a measurement sample. Next, the measurement sample is set in a moisture-permeable cup in which about 15 g of calcium chloride is placed. A moisture permeability test is performed by placing this moisture permeable cup in a thermostat set at a temperature of 40°C and a humidity of 92% RH and leaving it for 24 hours. By measuring the weight increase of calcium chloride before and after the test, the moisture permeability of the protective film can be specified.

The thickness of the protective film can be determined as appropriate, but is generally about 10 to 200 μm in terms of workability such as strength and handleability, and thinness.

The polarizer and the protective film are usually in close contact through a water-based adhesive or the like. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex, water-based polyurethane, and water-based polyester. Examples of adhesives other than the above-mentioned adhesives include ultraviolet curing adhesives and electron beam curing adhesives. The adhesive for electron beam curable polarizing plates exhibits suitable adhesiveness to various protective films. The adhesive may contain a metal compound filler.

In a polarizing plate, instead of a protective film, a retardation film or the like may be formed on the polarizer. On the protective film, it is also possible to provide a separate protective film, a retardation film, etc.

Regarding the protective film, a hard coat layer may be provided on the surface opposing the surface to which the polarizer is adhered, and treatment for the purposes of anti-reflection, anti-sticking, diffusion, anti-glare, etc. may be performed.

The light transmittance in the thickness direction of the optical laminated body 10A before the heating test is defined as Tsa ₀ , and the thickness of the optical laminated body 10A after heating the optical laminated body 10A at 95° C. for 500 hours The light transmittance in this direction is defined as Tsa ₅₀₀ . At this time, the difference in light transmittance before and after the heating test ΔTsa=Tsa ₅₀₀ -Tsa ₀ satisfies, for example, ΔTsa>0%. Accordingly, the optical laminate is suitable for use in environments where high temperatures must be considered. Details of the heating test are described in the Examples column.

The light transmittance in the thickness direction of the optical laminated body 10A before the heating test is defined as Tsb ₀ , and the thickness of the optical laminated body 10A after heating the optical laminated body 10A at 105° C. for 500 hours The light transmittance in this direction is defined as Tsb ₅₀₀ . At this time, the difference in light transmittance before and after the heating test ΔTsb=Tsb ₅₀₀ -Tsb ₀ satisfies, for example, ΔTsb>-10%. ΔTsb may satisfy ΔTsb>0%.

Another example of the optical laminated body of this embodiment is shown in FIG. 3. The optical laminate 10B in FIG. 3 has a laminated structure in which the release liner 3, the adhesive sheet 1, and the polarizing plate 2 are laminated in this order. The optical laminate 10B can be used as a polarizing plate with an adhesive sheet by peeling off the release liner 3. Each of the following examples may be combined with each other as long as there is no technical contradiction.

Constitutive materials of the release liner 3 include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foil, and these. Suitable thin-walled materials such as laminated materials may be used, but plastic films are preferably used because they have excellent surface smoothness.

The plastic film is not particularly limited as long as it is a film that can protect the adhesive sheet 1, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, Examples include vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, and ethylene-vinyl acetate copolymer film.

The thickness of the release liner 3 is usually about 5 to 200 μm, and preferably about 5 to 100 μm. If necessary, the release liner 3 is subjected to mold release and antifouling treatment using silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agents, silica powder, etc., or antistatic treatment such as coating type, paste type, or vapor deposition type. It's okay. In particular, by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release liner 3, the peelability from the adhesive sheet 1 can be further improved.

In addition, as described above, the base film used when producing the adhesive sheet 1 may be used as the release liner 3.

Another example of the optical laminated body of this embodiment is shown in FIG. 4. The optical laminate 10C in FIG. 4 has a laminated structure in which the release liner 3, the adhesive sheet 1, the retardation film 5, the interlayer adhesive 4, and the polarizing plate 2 are laminated in this order. The optical laminated body 10C can be used by, for example, attaching it to an image display cell after peeling off the release liner 3.

As the retardation film 5, one obtained by stretching a polymer film or one obtained by aligning and fixing a liquid crystal material can be used. The retardation film 5 has birefringence, for example, in-plane and/or in the thickness direction.

The retardation film 5 includes a retardation film for anti-reflection (see Japanese Patent Laid-Open No. 2012-133303 [0221], [0222], and [0228]), and a retardation film for viewing angle compensation (see Japanese Patent Laid-Open No. 2012-133303). [0225], [0226]), an oblique orientation retardation film for viewing angle compensation (see Japanese Patent Application Laid-Open No. 2012-133303 [0227]), and the like.

The specific configuration of the retardation film 5, such as retardation value, arrangement angle, three-dimensional birefringence, whether it is a single layer or a multilayer, etc., is not particularly limited, and a known retardation film can be used.

The thickness of the retardation film 5 is preferably 20 μm or less, more preferably 10 μm or less, further preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

The retardation film 5 may include, for example, a quarter wave plate and/or a half wave plate in which the liquid crystal material is aligned and fixed.

A known adhesive can be used as the interlayer adhesive 4. The adhesive sheet (1) may be used for the interlayer adhesive (4).

Another example of the optical laminated body of this embodiment is shown in FIG. 5. The optical laminate 10D in FIG. 5 includes a release liner 3, an adhesive sheet 1, a retardation film 5, an interlayer adhesive 4, a polarizer 2, and a protective film 6 laminated in this order. It has a layered structure. The optical laminated body 10D can be used by, for example, attaching it to an image display cell after peeling off the release liner 3.

The protective film 6 has a function of protecting the polarizing plate 2, which is the outermost layer, during distribution and storage of the optical laminated body 10D and when the optical laminated body 10D is built into an image display device. . Additionally, the protective film 6 may function as a window to external space when built into an image display device. The protective film 6 is typically a resin film. The resin constituting the protective film 6 is, for example, polyester such as PET, polyolefin such as polyethylene and polypropylene, acrylic, cycloolefin, polyimide, and polyamide, with polyester being preferred. However, the protective film 6 is not limited to the above examples. The protective film 6 may be a glass film or a laminated film containing a glass film. The protective film 6 may be subjected to surface treatment such as anti-glare, anti-reflection, or anti-static treatment.

The protective film 6 may be bonded to the polarizing plate 2 with any adhesive. Bonding using the adhesive sheet 1 is also possible.

The optical laminated body of this embodiment can be distributed and stored, for example, as a rolled body obtained by winding a strip-shaped optical laminated body or as a sheet-shaped optical laminated body. The optical laminate of this embodiment is suitable for use in image display devices used in environments where static electricity is particularly likely to be generated, especially in vehicle displays. Examples of vehicle-mounted displays include panels for car navigation devices, cluster panels, and mirror displays. The cluster panel is a panel that displays the vehicle's driving speed, engine rotation speed, etc.

(Embodiment 6)

[Optical laminate]

Separate examples of optical laminates include adhesive sheets and optical films. An optical film is a polarizing plate containing a polarizer. After heating the optical laminate at 105° C. for 120 hours, the polarizing plate contains 70 ppm or less of formic acid by mass. When the content of formic acid contained in the polarizing plate is this low, coloring is unlikely to occur in the optical laminate even after passing through a high temperature environment.

Another example of the optical laminated body of this embodiment is shown in FIG. 6. The optical laminate 10E in FIG. 6 includes an adhesive sheet 7 and an optical film. The optical film in FIG. 6 is a polarizer 8. The polarizing plate 8 includes a polarizer. The adhesive sheet 7 and the polarizing plate 8 are stacked on each other. The optical laminate 10E can be bonded to an object (for example, an image display panel) via the adhesive sheet 7. The optical laminate 10E can be used as an optical film with an adhesive sheet attached thereto, and more specifically, as a polarizing plate with an adhesive sheet attached thereto. Examples of optical films other than the polarizer 8 are retardation films and laminated films containing a polarizer and/or a retardation film. The optical film may be a circularly polarizing plate. However, the optical film is not limited to the above examples. The optical film may contain a glass film.

After heating the optical laminate 10E at 105°C for 120 hours, the content of formic acid contained in the polarizing plate is 65 ppm or less, 60 ppm or less, 55 ppm or less, 50 ppm or less, 45 ppm or less, 40 ppm or less, 35 ppm or less, 30 ppm or less, and It may be less than 28ppm. The lower limit of the content of formic acid is not particularly limited, and is, for example, 0 ppm or more.

According to the examination by the present inventors, it has been found that unnecessary coloring tends to occur in an optical laminate after being exposed to a high temperature environment. A possible cause of coloration is polyenylation of PVA by an acid contained in the polarizing plate, such as formic acid. The details of polyenylation of PVA with formic acid are the same as described in Embodiment 2.

The pressure-sensitive adhesive sheet 7 is formed, for example, from the pressure-sensitive adhesive composition (IV). The adhesive composition (IV) includes, for example, polymer (C) and a crosslinking agent. The adhesive composition (IV) may contain polymer (C) as a main component. “Main component” has the meaning described above.

Examples of polymer (C) are (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. Polymer (C) is preferably a (meth)acrylic polymer. Polymer (C) can function, for example, as a base polymer for an acrylic adhesive. The polymer (C) may be a polymer having a relative dielectric constant of 5.0 or more at a frequency of 100 kHz. The relative dielectric constant may be 6.0 or more, 6.5 or more, 6.8 or more, 7.0 or more, 7.3 or more, and further 7.5 or more. The upper limit of the relative dielectric constant is not particularly limited, and is, for example, 10.0 or less.

The polymer (C) may have structural units derived from monomers shown in the following formula (1).

R ¹ in formula (1) is a hydrogen atom or a methyl group. R ² in formula (1) is an alkyl group that may be linear or may have branches, and is preferably a linear alkyl group. Examples of R ² are methyl group and ethyl group. n is an integer of 1 to 15, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5.

In the polymer (C), the content of the structural unit derived from the monomer shown in formula (1) is not particularly limited, and may be, for example, 15 to 99.5% by weight, 30 to 99% by weight, or 50 to 98% by weight. The weight% may be sufficient, 50 to 80 weight% may be sufficient, and 50 to 70 weight% may be sufficient.

As monomers constituting the polymer (C), in addition to the monomers shown in formula (1), (meth)acrylic monomers having an alkyl group of 1 to 30 carbon atoms in the side chain, hydroxyl group-containing monomers, aromatic ring-containing monomers, carboxyl group-containing monomers, and amino group-containing monomers. At least one monomer selected from the group consisting of monomers, amide group-containing monomers, and polyfunctional monomers can be mentioned. These monomers can be used individually or in combination. Since examples of these monomers are the same as monomer (A2) described in Embodiment 1, descriptions are omitted.

In the polymer (C), the content of the structural unit derived from the monomer is not particularly limited, and may be, for example, 0.1 to 50% by weight or 0.5 to 45% by weight. In some cases, the content of structural units derived from monomers in the polymer (C) may be 1 to 5% by weight. In addition, depending on the case, in the polymer (C), the content of the structural unit derived from the monomer may be 20 to 45% by weight, 25 to 45% by weight, or 30 to 45% by weight.

As the monomer component, in addition to the monomers shown in formula (1) and the above-mentioned monomers, a polymerizable functional group containing an unsaturated double bond such as a (meth)acryloyl group or vinyl group is used for the purpose of improving the adhesiveness and heat resistance of the adhesive sheet. Other monomers having can be used. Other monomers can be used individually or in combination.

When using other monomers as the monomer component, the content of the structural unit derived from the other monomer in the polymer (C) may be 30% by weight or less, 10% by weight or less, or 0% by weight (the structural unit (does not have) may be used.

The weight average molecular weight (Mw) of the polymer (C) is, for example, 1 million to 3 million, may be 1.2 million to 2.5 million, and may be 1.5 million to 2.3 million. When the weight average molecular weight of the polymer (C) is 1 million to 3 million, cracking of the adhesive sheet can be suppressed and the increase in viscosity and occurrence of gelation tend to be suppressed.

The adhesive composition (IV) may contain the polymer (C) described above. The adhesive composition (IV) may further contain a polymer other than the polymer (C).

The polymer (C) can be produced by known polymerization methods such as solution polymerization, radiation polymerization such as electron beam or UV, and various radical polymerizations such as block polymerization and emulsion polymerization. The polymer (C) obtained may be any of random copolymers, block copolymers, graft copolymers, etc.

The method and polymerization conditions for forming the polymer (C) may be the same as the method and polymerization conditions for forming the polymer (A) described in Embodiment 1, respectively. The types of solvent and polymerization initiator used to form the polymer (C) can also be those described in Embodiment 1.

Examples of crosslinking agents contained in the adhesive composition (IV) are isocyanate-based crosslinking agents and peroxide-based crosslinking agents. A peroxide-based crosslinking agent and an isocyanate-based crosslinking agent may be used together. The pressure-sensitive adhesive composition (IV) may contain an isocyanate-based crosslinking agent, a peroxide-based crosslinking agent, or both an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent. The isocyanate-based crosslinking agent and peroxide-based crosslinking agent described in Embodiment 1 can be used.

Additionally, the adhesive sheet 7 may be a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (I) described in Embodiment 1, may be a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (II) described in Embodiment 2, or may be a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (II) described in Embodiment 3. (III) may also be used. In the optical laminate 10E, using these adhesive sheets as the adhesive sheet 7 is particularly suitable for reducing the content of formic acid contained in the polarizing plate 8.

The polarizing plate 8 may be the same as the polarizing plate 2 described in Embodiment 5. The polarizing plate 8 may include a polarizer.

The optical laminated body of this embodiment may be the same as the optical laminated bodies 10A to 10D of Embodiment 5, except that the adhesive sheet 7 is used instead of the adhesive sheet 1.

(Embodiment 7)

[Image display panel]

An example of the image display panel of this embodiment is shown in Fig. 7. The image display panel 11A in FIG. 7 includes an optical laminated body 10A and further includes, for example, an image display cell 30A. In detail, the optical laminate 10A is bonded to the image display cell 30A via the adhesive sheet 1. Additionally, instead of the optical laminated body 10A, the optical laminated body 10B, 10C or 10D of FIGS. 3 to 5 can also be used (however, the release liner 3 is excluded). Additionally, instead of the optical laminated body 10A, the optical laminated body 10E of FIG. 6 can also be used.

The image display cell 30A includes, for example, an image forming layer 32, a first transparent substrate 31, and a second transparent substrate 33. The image forming layer 32 is, for example, disposed between the first transparent substrate 31 and the second transparent substrate 33, and is in contact with each of the first transparent substrate 31 and the second transparent substrate 33. there is. The adhesive sheet 1 of the optical laminated body 10A is in contact with the first transparent substrate 31 of the image display cell 30A, for example.

The image forming layer 32 is, for example, a liquid crystal layer containing homogeneously aligned liquid crystal molecules in the absence of an electric field. A liquid crystal layer containing such liquid crystal molecules is suitable for the IPS (In-Plane-Switching) method. However, the liquid crystal layer may be used for TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, π type, VA (Vertical Alignment) type, etc. In this specification, an image display cell provided with a liquid crystal layer may be referred to as a liquid crystal cell, and an image display panel provided with a liquid crystal cell may be referred to as a liquid crystal panel. Additionally, the image forming layer 32 may be an EL emitting layer.

The thickness of the image forming layer 32 is, for example, 1.5 μm to 4 μm.

Examples of materials for the first transparent substrate 31 and the second transparent substrate 33 include glass and polymer. In this specification, a transparent substrate made of polymer may be referred to as a polymer film. Examples of polymers that constitute the transparent substrate include polyethylene terephthalate, polycycloolefin, and polycarbonate. The thickness of the transparent substrate made of glass is, for example, 0.1 mm to 1 mm. The thickness of the transparent substrate made of polymer is, for example, 10 μm to 200 μm.

The image display cell 30A may further include layers other than the image forming layer 32, the first transparent substrate 31, and the second transparent substrate 33. Examples of other layers include a color filter, an easy-to-adhere layer, and a hard coat layer. The color filter is, for example, disposed on the viewing side of the image forming layer 32, and is preferably located between the first transparent substrate 31 and the adhesive sheet 1 of the optical laminate 10A. The easy-adhesion layer and the hard coat layer are disposed on the surface of the first transparent substrate 31 or the second transparent substrate 33, for example.

The image display panel 11A may further include members other than the optical laminated body 10A and the image display cell 30A. For example, the image display panel 11A may further include a conductive structure (not shown) electrically connected to the side surface of the optical laminate 10A. By connecting the conductive structure to ground, it is easy to suppress the optical laminate 10A from being charged by static electricity. The conductive structure may cover the entire side surface of 10A of optical laminated bodies, or may partially cover the side surface of 10A of optical laminated bodies. The area ratio of the side surface of the optical laminated body 10A covered by the conductive structure to the area of the entire side surface of the optical laminated body 10A is, for example, 1% or more, and is preferably 3% or more.

Examples of materials for the conductive structure include conductive pastes made of metals such as silver and gold; conductive adhesive; Other challenging materials may be mentioned. The conductive structure may be a wiring extending from the side surface of the optical laminate 10A.

The image display panel 11A may further include an optical film other than the polarizing plate 2. Examples of other optical films include films used in image display devices such as polarizers, reflectors, transflective plates, viewing angle compensation films, and brightness enhancement films. The image display panel 11A may be provided with one or two or more different optical films among these.

When the other optical film is a polarizing plate, the polarizing plate is bonded to the second transparent substrate 33 of the image display cell 30A through, for example, an adhesive sheet. This polarizing plate has, for example, the structure described above with respect to the polarizing plate 2. In a polarizing plate as another optical film, the transmission axis (or absorption axis) of the polarizer is orthogonal to the transmission axis (or absorption axis) of the polarizer in the polarizing plate 2, for example. As a material for the adhesive sheet for bonding the polarizing plate and the second transparent substrate 33, the material described above for the adhesive sheet 1 can be used. The thickness of this adhesive sheet is not particularly limited, and is, for example, 1 to 100 μm, preferably 2 to 50 μm, more preferably 2 to 40 μm, and still more preferably 5 to 35 μm.

Another example of the image display panel of this embodiment is shown in Fig. 8. The image display panel 11B in FIG. 8 further includes a conductive layer 40 disposed between the optical laminate 10A and the image display cell 30A.

The conductive layer 40 is, for example, a layer containing a conductive agent. As the conductive agent, those described above for the adhesive sheet 1 can be used. However, the conductive agent is not limited to the above examples. The conductive layer 40 is a conductive polymer that is a complex of various conductive agents, such as carbon nanotubes, ITO, ATO, and a dopant (for example, a complex of poly(3,4-ethylenedioxythiophene) and polystyrenesulfonic acid: PEDOT. /PSS), etc. The thickness of the conductive layer 40 is, for example, 5 nm to 180 nm. The surface resistance value of the conductive layer 40 is, for example, 1.0×10 ⁶ Ω/□ to 1.0×10 ¹⁰ Ω/□, and preferably 1.0×10 ⁸ Ω/□ to 1.0×10 ⁹ Ω/□. .

Another example of the image display panel of this embodiment is shown in Fig. 9. The image display panel 11C in FIG. 9 includes an image display cell 30B that further includes a touch sensing electrode portion 35. In the image display cell 30B, the touch sensing electrode portion 35 is disposed between the first transparent substrate 31 and the second transparent substrate 33. The touch sensing electrode unit 35 has the functions of a touch sensor and touch drive. The image display panel 11C is a so-called in-cell type image display panel, and the image display cell 30B is a so-called in-cell type image display cell.

The touch sensing electrode unit 35 has, for example, a touch sensor electrode 36 and a touch driving electrode 37. The touch sensor electrode 36 refers to a (receiving) electrode for touch detection. The touch sensor electrode 36 and the touch drive electrode 37 can each be independently formed in various patterns. For example, when the image display cell 30B is flat, the touch sensor electrode 36 and the touch drive electrode 37 are provided independently in the X-axis direction and the Y-axis direction, respectively, and a pattern in which they intersect at right angles It can be formed as In FIG. 9 , in the touch sensing electrode portion 35, the touch sensor electrode 36 is disposed on the viewing side of the touch driving electrode 37. However, the touch drive electrode 37 may be disposed on the viewing side of the touch sensor electrode 36. In the touch sensing electrode portion 35, the touch sensor electrode 36 and the touch drive electrode 37 may be integrated.

In FIG. 9 , the touch sensing electrode portion 35 is disposed between the image forming layer 32 and the first transparent substrate 31 (on the viewing side of the image forming layer 32). However, the touch sensing electrode portion 35 may be disposed between the image forming layer 32 and the second transparent substrate 33 (on the lighting system side rather than the image forming layer 32).

In the touch sensing electrode portion 35, the touch sensor electrode 36 and the touch driving electrode 37 do not need to be in contact with each other. For example, the touch sensor electrode 36 is disposed between the image forming layer 32 and the first transparent substrate 31, and the touch driving electrode 37 is disposed between the image forming layer 32 and the second transparent substrate 33. It may be placed in .

The driving electrode in the touch sensing electrode portion 35 (the touch driving electrode 37, or the electrode in which the touch sensor electrode 36 and the touch driving electrode 37 are integrated) is a common electrode that controls the image forming layer 32. It can also serve as an electrode.

The touch sensor electrode 36 (capacitance sensor), the touch drive electrode 37, or the electrode formed by integrating them, which constitute the touch sensing electrode portion 35, functions as a transparent conductive layer. The material of this transparent conductive layer is not particularly limited, and includes, for example, metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, and tungsten, and alloys thereof. etc. can be mentioned. The material of the transparent conductive layer may be an oxide of a metal such as indium, tin, zinc, gallium, antimony, zirconium, or cadmium. Specific examples of this oxide include indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. The material of the transparent conductive layer may be a metal compound such as copper iodide. The material of the transparent conductive layer is preferably indium oxide (ITO) containing tin oxide, tin oxide (ATO) containing antimony, etc., and ITO is particularly preferred. When the material of the transparent conductive layer is ITO, the indium oxide content in the transparent conductive layer is preferably 80 to 99% by weight, and the tin oxide content is preferably 1 to 20% by weight.

The electrodes constituting the touch sensing electrode unit 35 (touch sensor electrode 36, touch driving electrode 37, or an electrode formed by integrating them) are formed of the first transparent substrate 31 and the second transparent substrate 33. ), it can be formed as a transparent electrode pattern by a normal method. This transparent electrode pattern is electrically connected to, for example, a routing line formed at the end of the transparent substrate. The routing line is connected to a controller IC, for example. As the shape of the transparent electrode pattern, any shape, such as a comb shape, a stripe shape, or a diamond shape, can be adopted depending on the application. The thickness of the transparent electrode pattern is, for example, 10 nm to 100 nm. The width of the transparent electrode pattern is, for example, 0.1 mm to 5 mm.

(Embodiment 8)

[Image display device]

The image display device of this embodiment includes, for example, an image display panel 11A and a lighting system. Additionally, instead of the image display panel 11A, the image display panels 11B and 11C of FIGS. 8 and 9 can also be used. In the image display device, the image display panel 11A is placed, for example, on a viewing side rather than the lighting system. The lighting system has, for example, a backlight or a reflector and irradiates light to the image display panel 11A.

The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to this example. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), or the like. The image display device can be used for home appliances, vehicle-mounted applications, public information display (PID) applications, etc., and is preferably a vehicle-mounted display.

[Example]

Hereinafter, the present invention will be explained in more detail through examples. The present invention is not limited to the examples shown below.

<Weight average molecular weight of (meth)acrylic polymer>

The weight average molecular weight (Mw) of the (meth)acrylic polymer was measured by GPC (gel permeation chromatography). Mw/Mn of the (meth)acrylic polymer was similarly measured.

·Analysis device: HLC-8120GPC manufactured by Tosoh Corporation

Column: Tosoh Corporation, G7000H _XL +GMH _XL +GMH _XL

·Column size: 7.8mmϕ×30cm each, total 90cm

·Column temperature: 40℃

·Flow rate: 0.8mL/min

·Injection volume: 100μL

·Eluent: Tetrahydrofuran

Detector: Differential refractometer (RI)

·Standard sample: polystyrene

[Preparation of (meth)acrylic polymer A1]

A monomer mixture containing 99 parts by weight of 2-methoxyethyl acrylate (MEA) and 1 part by weight of 4-hydroxybutylacrylate (HBA) in a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser. was invested. Additionally, with respect to 100 parts by weight of the monomer mixture, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) was added as a polymerization initiator along with 100 parts by weight of ethyl acetate. While gently stirring the mixture, nitrogen gas was introduced into the flask to perform nitrogen substitution. A solution of (meth)acrylic polymer A1 with a weight average molecular weight (Mw) of 1.8 million and Mw/Mn = 4.4 was prepared by performing a polymerization reaction for 8 hours while maintaining the liquid temperature in the flask at around 55°C.

[Preparation of (meth)acrylic polymer A2]

Except that the monomer mixture added to the flask was 60 parts by weight of MEA, 39 parts by weight of n-butylacrylate (BA), and 1 part by weight of HBA, the same procedure was performed as in the preparation of (meth)acrylic polymer A1, and the weight average molecular weight (Mw) ) A solution of (meth)acrylic polymer A2 of 1.75 million and Mw/Mn=3.5 was prepared.

[Preparation of (meth)acrylic polymer A3]

The monomer mixture added to the flask was similar to the preparation of (meth)acrylic polymer A1 except that 99 parts by weight of BA and 1 part by weight of HBA were prepared, and a (meth)acrylic polymer A1 with a weight average molecular weight (Mw) of 2 million and Mw/Mn = 4.5 was prepared. ) A solution of acrylic polymer A3 was prepared.

The monomers and input amounts used in the synthesis of each (meth)acrylic polymer are summarized in Table 1 below.

[Preparation of (meth)acrylic adhesive composition]

(Example A1)

Based on 100 parts by weight of solid content of the solution of (meth)acrylic polymer A1, 0.35 parts by weight of an isocyanate-based crosslinking agent (Coronate L; trimethylolpropantolylene diisocyanate, manufactured by Tosoh Corporation) and 5 parts by weight of bis (trifluorocarbonate) as a conductive agent. The (meth)acrylic adhesive composition of Example A1 was obtained by further mixing lithium methanesulfonyl)imide (LiTFSI; manufactured by Mitsubishi Material Denshi Chemicals) and 1 part by weight of an antioxidant (manufactured by BASF, Irganox1135, molecular weight 390). A solution was prepared.

(Example A2)

In the same manner as in Example A1, except that 0.1 part by weight of a peroxide-based crosslinking agent (Niper BMT, manufactured by Nippon Yushi Co., Ltd.) was further added, and the amount of antioxidant blended was 0.5 parts by weight, the (meth)acrylic system of Example A2 was prepared in the same manner as in Example A1. A solution of the adhesive composition was prepared.

(Examples A3 to A8)

As shown in Table 2 below, the isocyanate-based crosslinking agent, the peroxide-based crosslinking agent, antioxidant, and conductive agent were mixed with 100 parts by weight of the solid content of the (meth)acrylic polymer solution, and the (meth)acrylic polymer solutions (of Examples A3 to A8) were mixed. A solution of a meth)acrylic adhesive composition was prepared.

(Comparative Examples A1, A2)

As shown in Table 2 below, the isocyanate-based crosslinking agent, the peroxide-based crosslinking agent, and the conductive agent were mixed with respect to 100 parts by weight of the solid content of the solution of the (meth)acrylic polymer, and the (meth)acrylic polymers of Comparative Examples A1 and A2 were obtained. A solution of the adhesive composition was prepared.

[Production of adhesive sheet]

The solution of each adhesive composition was applied to one side of a polyethylene terephthalate film (release liner; manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) surface-treated with a silicone-based release agent so that the thickness of the adhesive sheet after drying was 20 μm. The obtained coating film was dried at 155°C for 1 minute to form an adhesive sheet on the surface of the release liner.

<Measurement of surface resistance value>

For each adhesive composition, the surface resistance value when forming an adhesive sheet was determined by using the adhesive sheet produced above as a test sample and using Hiresta MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. at an applied voltage of 250 V. , was measured under the condition of an application time of 10 seconds. The surface resistance value was measured in an environment with a temperature of 25°C ± 5°C and a relative humidity of 50 ± 5%.

[Production of optical laminate]

<Production of Polarizer A>

The polyvinyl alcohol film was stretched up to 3 times while dyeing for 1 minute in an iodine solution with a temperature of 30°C and a concentration of 0.3% by weight between rolls with different speed ratios. Next, it was stretched until the overall stretching ratio was 6 times while immersed in an aqueous solution at a temperature of 60°C containing boric acid at a concentration of 4% by weight and potassium iodide at a concentration of 10% by weight for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at a concentration of 1.5% by weight at a temperature of 30°C for 10 seconds and drying at 50°C for 4 minutes, a polarizer with a thickness of 18 μm was obtained. A 30-μm-thick transparent protective film made of a modified acrylic polymer with a lactone ring structure was bonded to one side of the polarizer using a polyvinyl alcohol-based adhesive. Additionally, a 47-μm-thick transparent protective film formed by forming a hard coat layer (HC) on a triacetylcellulose film (KC4UY, manufactured by Konica Minolta) was bonded to the other side of the polarizer using a polyvinyl alcohol-based adhesive. Polarizer A was produced by heating and drying in an oven set at 70°C for 5 minutes.

<Production of optical laminate>

Next, each adhesive sheet of Examples and Comparative Examples formed on the release liner was transferred to the polarizing plate produced above, and an optical laminate (polarizing plate with an adhesive sheet attached) was produced. Additionally, the adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of modified acrylic polymer.

<Coloring A>

The coloring of the optical laminate under high temperature was evaluated by the following method. The produced optical laminate was cut to a size of 45 x 40 mm so that the absorption axis of the polarizer was on the long side. Next, the cut optical laminate was bonded to a glass plate imitating the outermost layer of an image display panel through its adhesive sheet. Next, a glass plate imitating the front transparent member is bonded to the exposed surface on the polarizing plate side of the optical laminate through an adhesive (LUCIACS CS9821, manufactured by Nitto Denko; acrylic acid monomer-free adhesive, thickness 200 μm), and the image A laminate for evaluation modeled after a display device was produced. Next, a heating test was performed by leaving the laminate for evaluation in a hot air oven maintained at 105°C for 120 hours, and the light transmittance in the thickness direction of the laminate before and after the heating test was measured. The light transmittance was determined as the Y value (visibility correction was performed) using a spectrophotometer (LPF-200, manufactured by Otsuka Electronics Co., Ltd.) using a 2-degree field of view As the light source, a C light source was used. The measurement wavelength was 380 to 700 nm (every 10 nm). The measurement site for light transmittance in the laminate was near the center where coloring was thought to be progressing the most. The light transmittance before the heating test was set to Ts ₀ and the light transmittance after the heating test was set to Ts ₁₂₀ , and the degree of coloring of the optical laminate under high temperature was evaluated based on the value of the difference ΔTs = Ts ₁₂₀ -Ts ₀ .

A: ΔTs exceeds 0%

B: ΔTs is 0% or less and exceeds -3%

C: ΔTs is -3% or less and exceeds -10%

D: ΔTs is -10% or less

<Durability (high temperature durability A)>

The durability (high temperature durability) of the optical laminate was evaluated by the following method. The produced optical laminate was fixed to the surface of a glass plate (Corning, Eagle XG) via its adhesive sheet. Fixing was performed in an atmosphere of 24°C and 50%RH. Next, after processing in an autoclave at 50°C and 5 atm (absolute pressure) for 15 minutes, leaving until cooled to 24°C to stabilize the bonding of the optical laminate to the glass plate, it was placed in a heating atmosphere at 105°C. It was left for 500 hours. After leaving, it was returned to an atmosphere of 24°C and 50%RH, it was visually confirmed whether the polarizing plate was peeling from the glass plate or foaming was occurring between the glass plate and the polarizing plate, and durability was evaluated as follows.

A: No changes in appearance such as foaming or peeling are observed.

B: Although some individual peeling or foaming is seen at the end, it is within a range that is not problematic in practical terms.

C: At the end, some continuous peeling or foaming is observed, but it is within a range that is not problematic in practical terms.

D: Significant peeling or foaming is observed at the ends, which poses a problem in practical terms.

<Antistatic properties>

The antistatic property of the optical laminate was evaluated by the following method (ESD test). The produced optical laminate was fixed to the surface of the image display panel (surface on the viewing side) of Fig. 9 through its adhesive sheet. Next, the liquid crystal display panel on which the optical laminate was fixed was set on the backlight device, and static electricity was fired at an applied voltage of 15 kV to the surface of the polarizing plate, which is the exposed surface on the viewing side, using an electrostatic discharge gun. The time from the time of firing until the white part disappears due to static electricity was measured, and antistatic properties were evaluated as follows.

A: Disappears within 1 second

B: Exceeds 1 second and disappears within 10 seconds

C: Exceeds 10 seconds and disappears within 60 seconds

D: Disappears in excess of 60 seconds

The evaluation results of each optical laminate in Examples and Comparative Examples are shown in Table 3 below, along with the surface resistance values of the adhesive sheets used for each optical laminate. In addition, coloring (reddening) under high temperature in each optical laminate mainly occurred in the polarizer.

As shown in Table 3, in the optical laminate of the example, the adhesive sheet achieved a lower surface resistance value compared to the optical laminate of Comparative Example A2, and coloring under high temperature was suppressed. In addition, the optical laminate of Comparative Example A1 was manufactured even though the amount of the conductive agent mixed was greater than that of the Examples because the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive sheet did not contain a polymer (A) having a polyether structure. The surface resistance value increased. In addition, since the amount of the conductive agent mixed is large, it is considered that the durability as an optical laminate is reduced.

[Preparation of (meth)acrylic polymer B]

Except that the monomer mixture added to the flask was 98 parts by weight of MEA, 1 part by weight of n-butylacrylate (BA), and 1 part by weight of HBA, the same procedure was performed as in the preparation of (meth)acrylic polymer A1, and the weight average molecular weight (Mw) ) A solution of (meth)acrylic polymer B of 1.8 million and Mw/Mn=3.5 was prepared.

[Preparation of (meth)acrylic polymer C]

Except that the monomer mixture added to the flask was 60 parts by weight of MEA, 20 parts by weight of ethyl acrylate, 14 parts by weight of n-buty acrylate (BA), 5 parts by weight of phenoxyethyl acrylate, and 1 part by weight of HBA, ( In the same manner as the preparation of meth)acrylic polymer A1, a solution of (meth)acrylic polymer C with a weight average molecular weight (Mw) of 2 million and Mw/Mn = 3.9 was prepared.

[Preparation of (meth)acrylic adhesive composition]

(sample b1)

Based on 100 parts by weight of solid content of the solution of (meth)acrylic polymer B, 0.3 parts by weight of an isocyanate-based crosslinking agent (Takenate D-110N, manufactured by Mitsui Chemicals; trimethylolpropane/xylylene diisocyanate adduct) and 5 as a conductive agent. (meth) of sample b1 by further adding 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI; Elexel AS-110, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) A solution of an acrylic adhesive composition was prepared.

(sample b2)

Sample b2 (meth ) A solution of an acrylic adhesive composition was prepared.

(sample b3)

As shown in Table 4 below, the above-mentioned isocyanate-based crosslinking agent, peroxide-based crosslinking agent, and conductive agent were mixed with 100 parts by weight of solid content of the solution of (meth)acrylic polymer B to obtain a (meth)acrylic adhesive composition of sample b3. A solution was prepared.

(sample b4)

As shown in Table 4 below, the above-mentioned isocyanate-based crosslinking agent, peroxide-based crosslinking agent, and conductive agent were mixed with 100 parts by weight of solid content of the solution of (meth)acrylic polymer C to obtain a (meth)acrylic adhesive composition of sample b4. A solution was prepared.

<Measurement of relative permittivity>

For the (meth)acrylic polymers B and C of Examples and Comparative Examples, the relative dielectric constant P at a frequency of 100 kHz was measured by the method described above.

[Production of adhesive sheet]

The solution of each adhesive composition was applied to one side of a polyethylene terephthalate film (release liner; manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) surface-treated with a silicone-based release agent so that the thickness of the adhesive sheet after drying was 20 μm. The obtained coating film was dried at 155°C for 1 minute to form an adhesive sheet on the surface of the release liner.

<Measurement of surface resistance value>

For each adhesive composition, the surface resistance value when forming an adhesive sheet was determined by using the adhesive sheet produced above as a test sample and using Hiresta MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. at an applied voltage of 250 V. , was measured under the condition of an application time of 10 seconds. The surface resistance value was measured in an environment with a temperature of 25°C ± 5°C and a relative humidity of 50 ± 5%.

<Production of Polarizer A>

As polarizing plate A, the polarizing plate A described above was used.

<Production of Polarizer B>

A polarizer with a thickness of 28 μm was obtained in the same manner as in the production of polarizing plate A, except that the thickness and iodine concentration of the polyvinyl alcohol film used in the production of the polarizer were changed. Next, two types of transparent protective films were bonded to the obtained polarizer in the same manner as the production of polarizing plate A, and polarizing plate B was produced.

<Production of optical laminate>

Each of the adhesive sheets of Examples and Comparative Examples formed on the release liner was transferred to the polarizing plate produced above to produce a polarizing plate with an adhesive sheet attached thereto. Additionally, the adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of modified acrylic polymer. Then, in the polarizing plate with the adhesive sheet attached, an OCA layer composed of an optically transparent adhesive (OCA) is formed on the side of the polarizing plate opposite to the adhesive sheet, and the OCA layer, polarizing plate, adhesive sheet, and release liner are formed in this order. A laminated body was produced. The OCA layer contained butyl acrylate as a base polymer.

Next, the release liner was peeled from this laminate. In the laminate from which the release liner was peeled, glass was laminated on the surface opposite to the polarizing plate of the adhesive sheet and the surface opposite to the polarizing plate of the OCA layer. Accordingly, optical laminates of Examples and Comparative Examples in which glass, OCA layer, polarizing plate, adhesive sheet, and glass were laminated in this order were produced.

<Coloring a>

Coloring of the optical laminate under high temperature was evaluated in the same manner as in <Coloring A> above, except that a heating test was performed in which the laminate for evaluation was left in a hot air oven maintained at 95° C. for 500 hours. In addition, the light transmittance measurement portion of the laminate was set near the center where coloring was believed to be progressing the most. The light transmittance before the heating test was set to Tsa ₀ , the light transmittance after the heating test was set to Tsa ₅₀₀ , and the degree of coloring of the optical laminate under high temperature was evaluated based on the value of the difference ΔTsa = Tsa ₅₀₀ - Tsa ₀ .

A: ΔTsa exceeds 0%

B: ΔTsa is 0% or less and exceeds -3%

C: ΔTsa is -3% or less and exceeds -10%

D: ΔTsa is -10% or less

<Coloring b>

Coloring of the optical laminate under high temperature was evaluated in the same manner as in <Coloring A> above, except that a heating test was performed in which the laminate for evaluation was left in a hot air oven maintained at 105°C for 500 hours. In addition, the light transmittance measurement portion of the laminate was set near the center where coloring was believed to be progressing the most. The light transmittance before the heating test was set to Tsb ₀ and the light transmittance after the heating test was set to Tsb ₅₀₀ , and the degree of coloring of the optical laminate under high temperature was evaluated based on the value of the difference ΔTsb = Tsb ₅₀₀ - Tsb ₀ .

A: ΔTsb exceeds 0%

B: ΔTsb is 0% or less and exceeds -3%

C: ΔTsb is -3% or less and exceeds -10%

D: ΔTsb is -10% or less

<Durability (high temperature durability B)>

Except that the optical laminates of Examples B1 to B4 and Comparative Example B1 were used, the durability (high temperature durability) of the optical laminate was evaluated by the same method as the <Durability (high temperature durability A)> above.

<Measurement of formic acid content and acetic acid content in the adhesive sheet>

First, a heating test was performed on each of the adhesive sheets of Examples and Comparative Examples formed on the release liner by leaving them in a hot air oven maintained at 105°C for 120 hours.

Approximately 0.1 g of the adhesive sheet after the heat test was weighed and added to a PP container. An additional 50 mL of pure water was added to this PP container and the lid was placed on the PP container. Then, the PP container was placed in a dryer and heated at 120°C for 1 hour to perform extraction. The obtained extract was filtered through a membrane filter to obtain a filtrate. An analysis solution for ion chromatography measurement was prepared by removing organic substances from the obtained filtrate using a solid-phase extraction cartridge. This analysis solution was used for ion chromatography measurement (IC measurement). For the analysis solution, formic acid ions and acetic acid ions were quantified using an ion chromatograph to determine the content of formic acid contained in the adhesive sheet and the content of acetic acid contained in the adhesive sheet. For the ion chromatography measurement, ICS-3000 manufactured by Thermo Fisher Scientific was used.

<Measurement of formic acid content in polarizing plate>

First, a heating test was performed on the optical laminates of Examples and Comparative Examples by leaving them in a hot air oven maintained at 105°C for 120 hours. After the optical laminate after the heat test was immersed in liquid nitrogen and frozen, the glass formed on the surface of the OCA layer was peeled from the optical laminate, and the OCA layer was further scraped off and removed to obtain a laminate. Next, for this laminate, the glass formed on the surface of the adhesive sheet was peeled off, and the adhesive sheet was further physically removed from the polarizing plate. In this way, a polarizing plate was obtained from the optical laminated body. An analysis solution for ion chromatography measurement was prepared by the method described above, except that the obtained polarizing plate was used. By quantifying formic acid ions using an ion chromatograph, the content of formic acid contained in the polarizing plate was determined. The apparatus used for ion chromatography measurement was the same as described above.

Tables 5 and 6 show the evaluation results of each characteristic for the adhesive sheets and optical laminates produced in Examples and Comparative Examples. In Table 5, “<2.5” indicates that the formic acid content or acetic acid content was below the detection limit.

As shown in Tables 5 and 6, in the optical laminate of each Example, compared to the optical laminate of Comparative Example B1, the content of formic acid contained in the adhesive sheet is 1000 ppm or less on a mass basis, and coloring under high temperature is suppressed. Additionally, as shown in Table 5, in the optical laminate of each example, the content of formic acid contained in the polarizing plate was 70 ppm or less on a mass basis, and coloring under high temperature was suppressed. In addition, in the optical laminates of Examples and Comparative Examples, the acetic acid content was small even after passing through a high temperature environment.

(sample d1)

[Preparation of (meth)acrylic polymer D1]

A monomer mixture containing 99 parts by weight of 2-methoxyethyl acrylate (MEA) and 1 part by weight of 4-hydroxybutylacrylate was added to a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas introduction tube, and condenser. . Additionally, with respect to 100 parts by weight of the monomer mixture, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) was added as a polymerization initiator along with 100 parts by weight of ethyl acetate. While gently stirring the mixture, nitrogen gas was introduced into the flask to perform nitrogen substitution. A solution of (meth)acrylic polymer D1 with a weight average molecular weight (Mw) of 1.8 million and Mw/Mn = 4.4 was prepared by performing a polymerization reaction for 8 hours while maintaining the liquid temperature in the flask at around 55°C.

[Preparation of (meth)acrylic adhesive composition]

Next, based on 100 parts by weight of solid content of the solution of (meth)acrylic polymer D1, 0.35 parts by weight of an isocyanate-based crosslinking agent (Coronate L; trimethylolpropantolylene diisocyanate, manufactured by Tosoh Corporation) and 0.01 parts by weight of a peroxide-based crosslinking agent (Nippon Oil Co., Ltd. By further mixing 5 parts by weight of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI; manufactured by Mitsubishi Material Denshi Kasei Co., Ltd.) as a conductive agent, a (meth)acrylic adhesive composition (sample d1) was prepared. ) solution was prepared.

(sample d2)

A solution of the adhesive composition (sample d2) was prepared in the same manner as sample d1, except that the peroxide-based crosslinking agent was not added.

(sample d3)

A solution of the adhesive composition (sample d3) was prepared in the same manner as sample d1, except that the amount of the peroxide-based crosslinking agent was changed to 0.1 part by weight.

(sample d4)

An adhesive composition (sample d4) was prepared in the same manner as sample d3, except that 1.0 parts by weight of antioxidant (Irganox1135, manufactured by BASF Japan) was further added to 100 parts by weight of solid content of the solution of (meth)acrylic polymer D1. A solution was prepared.

(sample d5)

A solution of the adhesive composition (sample d5) was prepared in the same manner as sample d1, except that the compounding amount of the peroxide-based crosslinking agent was changed to 1.0 parts by weight.

The composition of each adhesive composition of samples d1 to d5 is shown in Table 7 below.

[Production of adhesive sheet]

The solution of each adhesive composition was applied to one side of a polyethylene terephthalate film (release liner; manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) surface-treated with a silicone-based release agent so that the thickness of the adhesive sheet after drying was 20 μm. The obtained coating film was dried at 155°C for 1 minute to form an adhesive sheet (samples d11 to d15 corresponding to each of the samples d1 to d5) on the surface of the release liner.

<Quantification of radical generation>

For each adhesive composition, the amount of radicals generated RG ₁₀ , RG ₂₀ , and RG ₃₀ when forming the adhesive sheet was evaluated by the method described above. However, the test piece (about 50 mg) stored in the ESR sample tube was collected from the adhesive sheet produced above. The measuring device and measurement conditions were as described below. The g value (center magnetic field) of the ESR signal used to calculate the amount of radical generation is the largest ESR signal intensity among the radicals generated due to the polyether structure that (meth)acrylic polymer D1 has in the side chain, and the intensity of the ESR signal is the highest for the PVA included in the polarizer. It was set to around 3352G (Gaussian), corresponding to the NO (nitroxide) radical, which is believed to have a large contribution to polyenization.

·Measurement device: EMXplus (BRUKER)

·Measuring conditions

measuring temperature 105℃

Magnetic field sweep range 200G

modulation 100kHz, 5G

microwave 9.40GHz, 1mW

postmark time 80 seconds x 4 times

time constant 327.68 milliseconds

Number of data points 1000points

cavity Super-high-Q

<Measurement of surface resistance value>

For each adhesive composition, the surface resistance value when forming an adhesive sheet was determined by using the adhesive sheet produced above as a test sample and using Hiresta MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. at an applied voltage of 250 V. , was measured under the condition of an application time of 10 seconds. The surface resistance value was measured in an environment with a temperature of 25°C ± 5°C and a relative humidity of 50 ± 5%.

[Production of optical laminate]

<Production of Polarizer A>

As polarizing plate A, the polarizing plate A described above was used.

<Production of Polarizer B>

As polarizing plate B, the polarizing plate B described above was used.

(Example D1)

The adhesive sheet of sample d11 formed on the release liner was transferred to the above-described polarizing plate A (polarizer thickness: 18 μm) to produce an optical laminate of Example D1 (polarizing plate with adhesive sheet attached). Additionally, the adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of modified acrylic polymer.

(Example D2)

An optical laminate of Example D2 was produced in the same manner as Example D1, except that the adhesive sheet of Sample d12 was used instead of Sample d11.

(Example D3)

An optical laminate of Example D3 was produced in the same manner as Example D1, except that the adhesive sheet of Sample d13 was used instead of Sample d11.

(Example D4)

An optical laminate of Example D4 was produced in the same manner as Example D1, except that the adhesive sheet of Sample d14 was used instead of Sample d11.

(Example D5)

An optical laminate of Example D5 was produced in the same manner as Example D1, except that the adhesive sheet of Sample d13 was used instead of Sample d11 and Polarizer B was used instead of Polarizer A.

(Comparative Example D1)

An optical laminate of Comparative Example D1 was produced in the same manner as Example D1, except that the adhesive sheet of Sample d15 was used instead of Sample d11.

<Color B>

A laminate for evaluation was produced using the optical laminates of Examples D1 to D5 and Comparative Example D1, and the laminate for evaluation was placed in a hot air oven maintained at 95°C or 105°C for 120 hours. The coloring of the optical laminate under high temperature was evaluated by the same method as in <Coloring A> above, except that the test was performed.

<Durability (high temperature durability) C>

Except that the optical laminates of Examples D1 to D5 and Comparative Example D1 were used, the durability (high temperature durability) of the optical laminate was evaluated by the same method as the <Durability (high temperature durability A)> above.

The evaluation results of each optical laminate in Examples and Comparative Examples are shown in Table 8 below, along with the evaluation results of the adhesive sheet used for each optical laminate. In addition, coloring (reddening) under high temperature in each optical laminate mainly occurred in the polarizer.

As shown in Table 8, in the optical laminate of the example, a lower surface resistance value of the adhesive sheet was achieved compared to the optical laminate of the comparative example, and coloring under high temperature was suppressed.

[Industrial applicability]

The adhesive composition of the present invention can be used in image display devices such as EL displays and liquid crystal displays, for example.

Claims (67)

Contains a polymer (A) having a polyether structure as a main component,
Further comprising a conductive agent and a radical scavenging agent,
A pressure-sensitive adhesive composition, wherein when the pressure-sensitive adhesive sheet is formed, the pressure-sensitive adhesive sheet has a surface resistance value of 1×10 ¹⁰ Ω/□ or less. The adhesive composition according to claim 1, wherein the polymer (A) is a (meth)acrylic polymer. The pressure-sensitive adhesive composition according to claim 1, wherein the polymer (A) has the polyether structure in the side chain. The adhesive composition according to claim 1, wherein the polymer (A) has a structural unit derived from a monomer shown in the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group which may be linear or may have branches, and n is an integer of 1 to 15. The pressure-sensitive adhesive composition according to claim 4, wherein the content of the structural unit in the polymer (A) is 25% by weight or more. The adhesive composition according to claim 1, wherein the surface resistance is 1×10 ⁹ Ω/□ or less. The adhesive composition of claim 1, wherein the radical scavenger is an antioxidant. The adhesive composition according to claim 1, wherein the radical scavenger has a molecular weight of 1000 or less. The adhesive composition according to claim 1, wherein the blending amount of the radical scavenger in the adhesive composition is less than 5 parts by weight with respect to 100 parts by weight of the polymer (A). The adhesive composition according to claim 1, wherein a blending amount of the conductive agent in the adhesive composition is 8 parts by weight or less with respect to 100 parts by weight of the polymer (A). The pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive composition further includes an isocyanate-based crosslinking agent. The pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive composition further includes a peroxide-based crosslinking agent. The adhesive composition according to claim 1, which is of solvent type. The adhesive composition according to claim 1, for use in an optical laminate. A pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition according to claim 1. The adhesive sheet according to claim 15,
optical film
An optical laminate containing a. The optical laminate according to claim 16, wherein the optical film is a polarizing plate including a polarizer. 18. The method of claim 17, further comprising a protective film,
An optical laminate in which the protective film is disposed on at least one side of the polarizer. An image display panel comprising the optical laminate according to claim 16. An image display device comprising the image display panel according to claim 19. It is an adhesive sheet formed of an adhesive composition containing polymer (B),
The relative dielectric constant of the polymer (B) at a frequency of 100 kHz is 5.0 or more,
After heating the adhesive sheet at 105° C. for 120 hours, the adhesive sheet contains 1000 ppm or less of formic acid on a mass basis. The adhesive sheet according to claim 21, wherein after heating the adhesive sheet at 105° C. for 120 hours, the adhesive sheet contains 100 ppm or less of formic acid on a mass basis. The pressure-sensitive adhesive sheet according to claim 21, wherein the polymer (B) is a (meth)acrylic polymer. The pressure-sensitive adhesive sheet according to claim 21, wherein the polymer (B) has a polyether structure in the side chain. The pressure-sensitive adhesive sheet according to claim 21, wherein the polymer (B) has a structural unit derived from a monomer shown in the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group which may be linear or may have branches, and n is an integer of 1 to 15. The pressure-sensitive adhesive sheet according to claim 21, wherein the pressure-sensitive adhesive composition further contains a peroxide-based crosslinking agent and a radical scavenger. 27. The pressure-sensitive adhesive sheet according to claim 26, wherein the radical scavenger is an antioxidant. The pressure-sensitive adhesive sheet according to claim 21, wherein the pressure-sensitive adhesive composition further includes an isocyanate-based crosslinking agent. 22. The pressure-sensitive adhesive sheet according to claim 21, for use in an optical laminate. The adhesive sheet according to claim 21,
optical film
An optical laminate containing a. The optical laminate according to claim 30, wherein the optical film is a polarizing plate including a polarizer. 32. The optical laminate of claim 31, wherein after heating the optical laminate at 105° C. for 120 hours, the polarizer contains 70 ppm or less of formic acid by mass. The method of claim 30, wherein the light transmittance after a heating test in which the optical laminate is heated at 95° C. for 500 hours is defined as Tsa ₅₀₀ , and the light transmittance of the optical laminate before the heating test is defined as Tsa ₀ , ΔTsa = Tsa ₅₀₀ -Tsa ₀ An optical laminate in which ΔTsa>0% is satisfied. 32. The method of claim 31, further comprising a protective film,
An optical laminate in which the protective film is disposed on at least one side of the polarizer. An image display panel comprising the optical laminate according to claim 30. An image display device comprising the image display panel according to claim 35. It is an optical laminate containing an adhesive sheet and an optical film,
The optical film is a polarizing plate including a polarizer,
After heating the optical laminate at 105° C. for 120 hours, the polarizing plate contains 70 ppm or less of formic acid by mass. The optical laminate according to claim 37, wherein the polarizer has a thickness of 20 μm or less. The optical laminate according to claim 37, wherein the pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive composition containing a polymer (C), and the relative dielectric constant of the polymer (C) at a frequency of 100 kHz is 5.0 or more. The optical laminate according to claim 39, wherein the polymer (C) is a (meth)acrylic polymer. The optical laminate according to claim 39, wherein the polymer (C) has a polyether structure in the side chain. The optical laminate according to claim 39, wherein the polymer (C) has a structural unit derived from a monomer shown in the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group which may be linear or may have branches, and n is an integer of 1 to 15. The optical laminate according to claim 39, wherein the pressure-sensitive adhesive composition further contains a peroxide-based crosslinking agent and a radical scavenger. 44. The optical laminate of claim 43, wherein the radical scavenger is an antioxidant. The optical laminate according to claim 39, wherein the pressure-sensitive adhesive composition further comprises an isocyanate-based crosslinking agent. An image display panel comprising the optical laminate according to claim 37. An image display device comprising the image display panel according to claim 46. Contains a polymer (D) having a polyether structure as a main component,
Includes more challenges,
An adhesive composition wherein, when formed, the adhesive sheet has a radical generation amount RG ₁₀ of 1.5 × 10 ¹⁴ pieces/g or less and a surface resistance value of 1 × 10 ¹⁰ Ω/□ or less.
However, RG ₁₀ is the amount of radicals generated by the adhesive sheet when heated at 105°C for 10 minutes, as evaluated by electron spin resonance method. The pressure-sensitive adhesive composition according to claim 48, wherein the polymer (D) is a (meth)acrylic polymer. The pressure-sensitive adhesive composition according to claim 48, wherein the polymer (D) has the polyether structure in the side chain. The adhesive composition according to claim 48, wherein the polymer (D) has a structural unit derived from a monomer shown in the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group which may be linear or may have branches, and n is an integer of 1 to 15. The pressure-sensitive adhesive composition according to claim 51, wherein the content of the structural unit in the polymer (D) is 25% by weight or more. The adhesive composition according to claim 48, wherein the surface resistance is 1×10 ⁹ Ω/□ or less. The adhesive composition according to claim 48, wherein the radical generation amount ratio RG ₂₀ /RG ₁₀ is less than 1.5.
However, the RG ₂₀ is the amount of radicals generated by the adhesive sheet when heated at 105°C for 20 minutes, as evaluated by electron spin resonance method. The adhesive composition according to claim 48, wherein the radical generation amount ratio RG ₃₀ /RG ₁₀ is less than 1.9.
However, RG ₃₀ is the amount of radicals generated by the adhesive sheet when heated at 105°C for 30 minutes, as evaluated by electron spin resonance method. The adhesive composition according to claim 48, wherein the mixing amount of the conductive agent in the adhesive composition is 8 parts by weight or less with respect to 100 parts by weight of the polymer (D). The pressure-sensitive adhesive composition of claim 48, wherein the pressure-sensitive adhesive composition further comprises an isocyanate-based crosslinking agent. 49. The pressure-sensitive adhesive composition of claim 48, wherein the pressure-sensitive adhesive composition further comprises a peroxide-based crosslinking agent. 49. The adhesive composition of claim 48, which is in solvent form. 49. The adhesive composition of claim 48 for use in an optical laminate. An adhesive sheet formed from the adhesive composition according to claim 48. The adhesive sheet according to item 61,
optical film
An optical laminate comprising: 63. The optical laminate of claim 62, wherein the optical film is a polarizing plate including a polarizer. 64. The method of claim 63, further comprising a protective film,
An optical laminate in which the protective film is disposed on at least one side of the polarizer. The optical laminate according to claim 63, wherein the polarizer has a thickness of 20 μm or less. An image display panel comprising the optical laminate according to claim 62. An image display device comprising the image display panel according to claim 66.

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