JP2023106410A - Adhesive composition, adhesive sheet, optical laminate, image display panel, and image display device - Google Patents

Abstract

To provide an adhesive composition and a formed adhesive sheet suitable for use for an optical laminate under a high temperature environment, while achieving a low surface resistance value.SOLUTION: An adhesive composition contains a polymer (A) having a polyether structure as a major component and further contains a conductive agent. The polymer (A) has a constitutional unit derived from a monomer represented by formula (1). An adhesive sheet formed from adhesive composition has a radical generation amount RG10 of 1.5×1014/g or less and a surface resistance value of 1×1010 Ω/square or less. The RG10 is a radical generation amount of the adhesive sheet when heated at 105°C for 10 minutes, evaluated by an electron spin resonance method. (R1 is H or a methyl group, R2 is an alkyl group, and n is an integer of 1-15).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, an adhesive sheet, an optical laminate, an image display panel and an image display device.

2. Description of the Related Art In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices) have rapidly spread. These various image display devices have a laminated structure of, for example, an image display cell such as a liquid crystal cell or an EL light emitting element, and an optical laminate including an optical film such as a polarizing plate and an adhesive sheet. The pressure-sensitive adhesive sheet is mainly used for bonding between optical films included in the optical layered body and bonding between the image display cell and the optical layered body. Patent Document 1 discloses a pressure-sensitive adhesive composition containing a (meth)acrylic polymer having a structural unit derived from a polar group-containing monomer such as 2-methoxyethyl acrylate, and a pressure-sensitive adhesive composition formed from the An adhesive sheet is disclosed.

Japanese Unexamined Patent Application Publication No. 2013-32428

In the image display device, static electricity is generated during manufacture, for example, when the optical layered body is adhered to the image display cell via an adhesive sheet, or during use, for example, when the user touches the image display device. If the image display device is electrified by this static electricity, problems such as display failure may occur. When using an image display device in an environment where static electricity is particularly likely to occur, for example, in an environment where there are other electronic devices around, such as inside a vehicle, to sufficiently prevent display defects due to charging of the image display device, adhesive It is conceivable to adjust the surface resistance value of the pressure-sensitive adhesive sheet to a low value by adding a conductive agent to the agent composition. However, if the compounding amount of the conductive agent is excessively increased, the optical properties will deteriorate due to the deposition of the conductive agent and the durability of the adhesive sheet will decrease when the high temperature environment assumed in the inside of the vehicle in summer etc. is passed. etc. tend to occur.

The present invention provides a pressure-sensitive adhesive composition that achieves a low surface resistance value and is suitable for use in optical laminates in environments where high temperatures should be considered, and a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition. aim.

The present invention
Containing a polymer (A) having a polyether structure as a main component,
further comprising a conductive agent;
When the pressure-sensitive adhesive sheet is formed, the pressure-sensitive adhesive sheet has a radical generation amount RG _of 1.5×10 ¹⁴ /g or less and a surface resistance value of 1×10 ¹⁰ Ω/□ or less. offer.
However, the RG ₁₀ is the amount of radicals generated from the pressure-sensitive adhesive sheet when heated at 105° C. for 10 minutes, as evaluated by an electron spin resonance method.

From another aspect, the present invention provides
A pressure-sensitive adhesive sheet formed from the above pressure-sensitive adhesive composition is provided.

From another aspect, the present invention provides
the above-mentioned adhesive sheet;
an optical film;
An optical laminate is provided, comprising:

From another aspect, the present invention provides
Provided is an image display panel comprising the above optical layered body.

From another aspect, the present invention provides
Provided is an image display device comprising the above image display panel.

According to the present invention, a pressure-sensitive adhesive composition that achieves a low surface resistance value and is suitable for use in an optical laminate under an environment where high temperatures should be considered, and a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition are provided. can provide.

FIG. 1 is a cross-sectional view schematically showing an example of the pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of the image display panel of the invention. FIG. 7 is a cross-sectional view schematically showing an example of the image display panel of the invention. FIG. 8 is a cross-sectional view schematically showing an example of the image display panel of the invention.

Although the present invention will be described in detail below, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention.

[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 studies of the present inventors, the polyether structure in the polymer (A) can promote the ionization of the conductive agent contained in the adhesive composition (I), and the ionization of the conductive agent It can contribute to the reduction of the surface resistance value of the pressure-sensitive adhesive sheet formed from the material.

Further, according to further studies, when a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing (i) a polymer (A) having a polyether structure as a main component is used for an optical laminate, after passing through a high-temperature environment, unnecessary (ii) coloration is often observed when a polarizing plate is included in the optical layered body; It has been found that the mechanism is presumed that the radicals generated due to the ether structure migrate to the optical film and act on the polymer contained in the optical film. As an action of radicals on a polymer, for example, polyene conversion of polyvinyl alcohol (PVA), which is a typical polymer contained in polarizers, can be considered. Polyenation of PVA is a phenomenon in which multiple carbon-carbon unsaturated bonds occur in the main chain of PVA and the conjugated structure extends. is red). The polyene formation of PVA can be explained as a phenomenon in which the cross-linked structure with boric acid disappears due to hydrolysis caused by heat, exposing many terminal OH groups of PVA, and the dehydration condensation reaction between the exposed OH groups proceeds. Moreover, this dehydration condensation reaction is presumed to be a radical reaction. In addition, it is considered that progress of radical reaction in the optical film at high temperature, not limited to PVA in the polarizer, can cause changes in optical properties such as coloration to the optical film. Radicals generated due to the polyether structure include radicals generated with the involvement of other components (e.g., polymerization initiators, cross-linking agents, antioxidants, etc.) starting from the radicals generated from the polyether structure. can be included.

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

The radical generation amount RG ₁₀ is 1.3×10 ¹⁴ /g or less, 1.0×10 ¹⁴ /g or less, 9.0×10 ¹³ /g or less, and further 8.0×10 ¹³ /g or less. g or less. Although the lower limit of the radical generation amount RG ₁₀ is not limited, it is, for example, 1.0×10 ¹⁰ /g or more.

When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition (I), the radical generation amount RG ₂₀ in the formed pressure-sensitive adhesive sheet is, for example, 2.5 × 10 ¹⁴ /g or less, 2.0 × 10 ¹⁴ /g or less. g or less, 1.5×10 ¹⁴ pieces/g or less, 1.2×10 ¹⁴ pieces/g or less, or 1.0×10 ¹⁴ pieces/g or less. Although the lower limit of the radical generation amount RG ₂₀ is not limited, it is, for example, 1.0×10 ¹⁰ /g or more. However, the radical generation amount RG ₂₀ is the radical generation amount of the pressure-sensitive adhesive sheet when heated at 105° C. for 20 minutes, as evaluated by ESR. The pressure-sensitive adhesive composition (I) having a radical generation amount RG ₂₀ in the pressure-sensitive adhesive sheet within the above range is particularly suitable for use in optical laminates under high-temperature environments.

The ratio of RG ₂₀ to radical generation amount RG ₁₀ (radical generation amount ratio RG ₂₀ /RG ₁₀ ) is, for example, 1.7 or less, 1.5 or less, less than 1.5, 1.4 or less, 1.4. It may be less than or even 1.3 or less. The lower limit of _RG20 / _RG10 is, for example, 0.8 or more. The pressure-sensitive adhesive composition (I) having RG ₂₀ /RG ₁₀ within the above range when formed into a pressure-sensitive adhesive sheet is particularly suitable for use in optical laminates under high-temperature environments.

When a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition (I), the radical generation amount RG ₃₀ in the formed pressure-sensitive adhesive sheet is, for example, 3.0 × 10 ¹⁴ /g or less, 2.5 × 10 ¹⁴ /g or less. g or less, 2.0×10 ¹⁴ pieces/g or less, 1.7×10 ¹⁴ pieces/g or less, 1.5×10 ¹⁴ pieces/g or less, 1.4×10 ¹⁴ pieces/g or less, 1.3 It may be 1.2×10 ¹⁴ pieces/g or less, or 1.2×10 ¹⁴ pieces/g or less. Although the lower limit of the radical generation amount RG ₃₀ is not limited, it is, for example, 1.0×10 ¹⁰ /g or more. However, the radical generation amount RG ₃₀ is the radical generation amount of the pressure-sensitive adhesive sheet when heated at 105° C. for 30 minutes as evaluated by ESR. The pressure-sensitive adhesive composition (I) having a radical generation amount RG ₃₀ within the above range when formed into a pressure-sensitive adhesive sheet is particularly suitable for use in optical laminates under high-temperature environments.

The ratio of RG ₃₀ to radical generation amount RG ₁₀ (radical generation amount ratio RG ₃₀ /RG ₁₀ ) is, for example, 2.2 or less, 2.0 or less, 1.9 or less, less than 1.9, 1.7. 1.6 or less, or even 1.5 or less. The lower limit of _RG30 / _RG10 is, for example, 0.8 or more. The pressure-sensitive adhesive composition (I) having RG ₃₀ /RG ₁₀ within the above range when formed into a pressure-sensitive adhesive sheet is particularly suitable for use in optical laminates under environments where high temperatures should be considered.

The radical generation amount of the pressure-sensitive adhesive composition (I) can be evaluated as follows. First, a part of the adhesive sheet formed from the adhesive composition to be evaluated is collected, packed in the tip portion of the ESR sample tube, and the sample tube is sealed. The amount of the part contained in the sample tube is about 50 mg. When the pressure-sensitive adhesive composition is in a state before forming a pressure-sensitive adhesive sheet (as an example, in the form of a solution), for example, a pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition based on the method for producing a pressure-sensitive adhesive sheet described later, and the formed pressure-sensitive adhesive Take a portion of the sheet. Next, the sample tube was set in the ESR device and heated from room temperature (25±5°C) to 105°C at a heating rate of 30°C/min. , and 30 minutes, ESR measurements are performed. The amount of radical generation can be quantitatively calculated from the signal intensity of the ESR signal observed by the measurement. The ESR signal corresponding to the generated radicals can be selected based on the signal's g-value (the center position of the signal) and the splitting width. ESR signals corresponding to radicals may be looked for by comparing them with profiles obtained by performing ESR measurements without heating. The ESR signal corresponding to radicals may be a signal of radicals generated with the involvement of other components starting from radicals generated from the polyether structure. The strongest signal can be selected from among the ESR signals corresponding to radicals. It is well known to those skilled in the art that ESR enables quantitative evaluation of radicals contained in substances. The amount of radicals generated in the pressure-sensitive adhesive sheet (cured product of the pressure-sensitive adhesive composition) can also be evaluated in detail according to known methods.

The amount of radicals generated in the adhesive composition is, for example, the composition of the adhesive composition, the composition and content of the polymer (A), the type and content of the conductive agent, the adhesive composition other than the polymer (A) and the conductive agent. It may change depending on the type, content and combination of materials blended in the adhesive sheet, the degree of curing of the adhesive sheet, and the like. The degree of curing of the pressure-sensitive adhesive sheet, for example, in the case of a solvent-based pressure-sensitive adhesive composition (I), depends on the solid content concentration and viscosity of the solution containing the pressure-sensitive adhesive composition, and the conditions for forming a coating film on the substrate film. , conditions for drying the coating film, and when the device for drying the coating film (heating furnace, etc.) is a non-sealed type, the temperature and humidity of the atmosphere in which the device is placed may change.

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, or even 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) having a surface resistance value within the above range when formed into a pressure-sensitive adhesive sheet is suitable for use in an environment where static electricity is likely to occur, such as 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. Polymer (A) is preferably a (meth)acrylic polymer. In other words, the pressure-sensitive adhesive composition (I) may contain a (meth)acrylic polymer as a main component. Furthermore, in other words, the adhesive composition (I) may be an acrylic adhesive composition. A main component means the component with the largest content rate in a 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, or even 80% by weight or more. As used herein, the (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, 85 wt % or more, 90 wt % or more, or even 95 wt % or more. The (meth)acrylic polymer may consist only of 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 branched. An example of a polyether structure includes an alkyl group, which may be linear or branched, and at least two ether groups. The polymer (A) may have a polyether structure in its main chain or in its side chains, preferably in its side chains. The polymer (A) may be a (meth)acrylic polymer having polyether structures in side chains.

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

An example of the polymer (A) having a polyether structure in its side chain has a structural unit derived from a monomer represented by formula (1) below. 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 branched, preferably a linear alkyl group. Examples of R ² are methyl and ethyl groups. n is an integer of 1-15, preferably an integer of 1-10, more preferably an integer of 1-5. When n is 1, the monomer of formula (1) contains two ether groups, including the "-O-" of the COO group. The monomer of formula (1) is one type of (meth)acrylic monomer, more specifically, one type of (meth)acrylate monomer. Focusing on the R ² O group at the end of the side chain, the monomer of formula (1) is also one type of alkoxy group-containing (meth)acrylate monomer. A structural unit derived from the monomer of formula (1) has a polyether structure in its side chain.

Examples of monomers of formula (1) are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate. ) acrylates and methoxypolyethylene glycol (meth)acrylates, preferably 2-methoxyethyl acrylate (MEA). The structural unit derived from the monomer of formula (1) can particularly contribute to lowering the surface resistance of the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition (I).

The content of structural units having a polyether structure (for example, structural units derived from the monomer of formula (1)) in the polymer (A) is, for example, 15% by weight or more, 20% by weight or more, and 25% by weight. Above, 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% by weight 80% by weight or more, 85% by weight or more, 90% by weight or more, or even 95% by weight or more. The upper limit of the content is, for example, 100% by weight or less, and may be 99.5% by weight or less, or even 99% by weight or less.

The polymer (A) may have one or more structural units derived from the following monomers (A2). 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 having 1 to 30 carbon atoms in its side chain. The alkyl group may be linear or branched. Examples of (meth)acrylic monomers having alkyl groups in side chains include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and n-butyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)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 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. The content of the structural unit derived from the (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, 40 wt% or less, 30 wt% or less, 20 wt% or less, 10 wt% or less, or even 5 wt% or less, or even 0 wt% (without the structural unit even) good.

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

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, ethylene oxide-modified nonylphenol (meth) acrylate, 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 are (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N- Butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylol-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl acrylamide-based monomers such as (meth)acrylamide and mercaptoethyl (meth)acrylamide; N-acryloyl heterocycles 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.

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

The total content of structural units derived from the aromatic ring-containing monomer, carboxyl group-containing monomer, amino group-containing monomer, amide group-containing monomer and polyfunctional monomer in the polymer (A) is , preferably 20% by weight or less, more preferably 10% by weight or less, and even 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, or even 3% by weight or more. Polymer (A) may not 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 even 0% by weight (if the structural unit is (even without it) is fine.

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 methylglycidyl (meth)acrylate; vinyl sulfonic acid group-containing monomers such as sodium sulfonate; phosphate group-containing monomers; alicyclic hydrocarbon groups 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 such as ethylene, propylene, butadiene, isoprene and isobutylene, or dienes; vinyl ethers such as alkyl ethers; and vinyl chloride.

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

The polymer (A) can be formed by polymerizing one or more of the above monomers by a known method. A monomer and a partial polymer of the monomer may be polymerized. Polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. Solution polymerization and active energy ray polymerization are preferred from the viewpoint of forming a pressure-sensitive adhesive sheet with excellent optical transparency. Polymerization is preferably carried out while avoiding contact of the monomer and/or partial polymer with oxygen. Polymerization in shutdown can be employed. The polymer (A) to be formed may be in any form such as a random copolymer, a block copolymer, a graft copolymer and the like.

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

Solvents used for solution polymerization include 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 methylcyclohexane; and 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 for solution polymerization are, for example, azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Peroxide polymerization initiators are, for example, dibenzoyl peroxide and t-butyl permaleate. Among them, the azo polymerization initiator disclosed in JP-A-2002-69411 is preferable. The azo polymerization initiator, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis (2-methylpropion 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, per 100 parts by weight of the total amount of the monomers.

Active energy rays used for 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. The active energy rays are preferably ultraviolet rays. Polymerization by irradiation with ultraviolet rays is also called photopolymerization. A polymerization system for active energy ray polymerization typically contains a photopolymerization initiator. Polymerization conditions for active energy polymerization are not limited as long as the 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, and photoactive oxime-based photopolymerization initiators. , a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a 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, 2,2-dimethoxy-1,2-diphenylethan-1-one, anisolemethyl is ether. Acetophenone-based photopolymerization initiators include, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloro Acetophenone. Examples of α-ketol photopolymerization initiators are 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. The aromatic sulfonyl chloride 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. A benzoin-based photopolymerization initiator is, for example, benzoin. A benzylic photopolymerization initiator is, for example, benzyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. A ketal photopolymerization initiator is, for example, benzyl dimethyl ketal. Thioxanthone-based photopolymerization initiators are, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 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 part by weight, per 100 parts by weight of the total amount of the monomers.

The weight average molecular weight (Mw) of the polymer (A) is, for example, 1-3 million, preferably 1.8-3 million. When the weight-average molecular weight of the polymer (A) is 1,000,000 to 3,000,000, cracks in the pressure-sensitive adhesive sheet can be suppressed, and there is a tendency to suppress increase in viscosity and occurrence of gelation. The weight average molecular weight (Mw) of the polymer in this specification is a value (converted to polystyrene) based on GPC (gel permeation chromatography) measurement.

The glass transition temperature (Tg) of the polymer (A) is, for example, -50°C or lower, preferably -52°C or lower, 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 averaging the Tg of a homopolymer for each monomer that forms the structural unit of the polymer (A) and taking into account the content of the structural unit. is.

The content of the polymer (A) in the pressure-sensitive adhesive composition (I) is, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 75% by weight or more, or even 80% by weight in terms of solid content. or more. The upper limit of the content is, for example, 99% by weight or less, and may be 97% by weight or less, or even 95% by weight or less.

<Conductive agent>
The adhesive composition (I) further contains a conductive agent (antistatic agent). The pressure-sensitive adhesive composition (I) may contain one or more conductive agents. Examples of conductive agents are ionic compounds such as salts. The ionic compound may be an ionic liquid that is liquid at normal temperature (25° C.).

Examples of ionic compounds are inorganic and organic cation salts. Examples of inorganic cation salts are inorganic cation-anion salts. Examples of cations contained in inorganic cation salts are alkali metal ions. Alkali metal ions are, for example, lithium ions, sodium ions, potassium ions, preferably lithium ions. The inorganic cation salt may be a lithium salt.

Examples of anions contained 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 ⁻ , _CF3COO- , ^CH3SO3- _{, CF3SO3-} ^, _{( CF3SO2 ) 3C-} ^, _{AsF6- ,} ^{SbF6- ,} _NbF6- ^{, TaF6- ,} _{( CN} ⁾ _2N- , _{C4F9SO3- , C3F7COO-} ^, _{(CF3SO2)(CF3CO)N-, -O3S ( CF2 )} ^{3SO3- , and} _{the following} ^general _{formula (} a) _: is an anion represented by (d).
(a) ( _{CnF2n +1SO2 ) 2N-} (n is ^an integer of 1 to 10)
(b) _CF2 ( _CmF2mSO2 ) _2N- (m _is ^an integer _of 1 to 10)
(c) ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (l is an integer of 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 from 1 to 10)

The anion contained in the inorganic cation salt is preferably a fluorine-containing anion, more preferably a fluorine-containing imide anion. Examples of fluorine-containing imide anions are imide anions with perfluoroalkyl groups. More specific examples of fluorine-containing imide anions are (CF ₃ SO ₂ )(CF ₃ CO)N ⁻ and anions represented by the above general formulas (a), (b) or (d), Preferred are ( _{CF3SO2 ) 2N-} ^, ( _C2F5SO2 ) _2N- and other ( _{perfluoroalkylsulfonyl} ⁾ imides represented by _the general formula (a), more _preferably ( _CF3SO2 ) ₂ N ^- is bis(trifluoromethanesulfonyl)imide. An example of a preferred inorganic cation salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

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

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

As the conductive agent, an inorganic cation salt and an organic cation salt may be used in combination.

The 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, or 3 parts by weight or more with respect to 100 parts by weight of the polymer (A). , and may be 4 parts by weight or more. The upper limit of the 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, with respect to 100 parts by weight of the polymer (A). It may be 7 parts by weight or less, or even 6 parts by weight or less.

<Additive>
The pressure-sensitive adhesive composition (I) may further contain materials other than the polymer (A) and the conductive agent. Examples of such materials are additives. Examples of additives include cross-linking agents, silane coupling agents, coloring agents such as pigments and dyes, UV absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, softening agents, agents, antioxidants, anti-aging agents, light stabilizers, polymerization inhibitors, rust inhibitors, inorganic fillers, organic fillers, powders such as metal powders, particles, and foils. 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 per 100 parts by weight of the polymer (A).

Examples of crosslinkers are organic crosslinkers and multifunctional metal chelates. Examples of organic cross-linking agents are isocyanate cross-linking agents, peroxide cross-linking agents, epoxy cross-linking agents and imine cross-linking agents. The organic cross-linking agent and polyfunctional metal chelate can be used for both the solvent-type and active energy ray-curable pressure-sensitive adhesive compositions (I). When the pressure-sensitive adhesive composition (I) is a solvent type, the cross-linking agent is preferably a peroxide-based cross-linking agent or an isocyanate-based cross-linking agent. A peroxide-based cross-linking agent and an isocyanate-based cross-linking agent may be used in combination. The pressure-sensitive adhesive composition (I) may contain an isocyanate cross-linking agent, may contain a peroxide cross-linking agent, or may contain both an isocyanate cross-linking agent and a peroxide cross-linking agent. good too.

Examples of isocyanate cross-linking agents include aromatic isocyanate compounds such as tolylene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate and polymethylene polyphenyl isocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate and alicyclic isocyanate compounds such as isophorone diisocyanate; and aliphatic isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate and hexamethylene diisocyanate. The isocyanate-based cross-linking agent is a compound (adduct) obtained by adding the above-mentioned isocyanate compound to a polyhydric alcohol compound such as trimethylolpropane; A compound subjected to an addition reaction with a polyol; a derivative of the isocyanate compound such as an isocyanurate compound may be used. Specific examples of derivatives include trimethylolpropane/tolylene diisocyanate trimer adduct (eg, Tosoh Corporation, Coronate L), trimethylolpropane/hexamethylene diisocyanate trimer adduct (eg, Tosoh Corporation, Coronate HL ), an isocyanurate of hexamethylene diisocyanate (eg, Coronate HX manufactured by Tosoh Corporation).

When the pressure-sensitive adhesive composition (I) contains an isocyanate-based cross-linking agent, the amount thereof is, for example, 0.1 to 10 parts by weight and 0.2 to 5 parts by weight with respect to 100 parts by weight of the polymer (A). , 0.25 to 3 parts by weight, 0.3 to 1 part by weight, or even 0.3 to 0.5 parts by weight.

Examples of peroxide-based cross-linking agents include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy Neodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2 -ethylhexanoate, di(4-methylbenzoyl)peroxide, benzoylperoxide, t-butylperoxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane. The peroxide-based cross-linking agent may be benzoyl peroxide because of its excellent cross-linking reaction efficiency.

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

Examples of silane coupling agents are 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Epoxy group-containing silane coupling agents such as trimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3 -Dimethylbutylidene)propylamine, amino group-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane; ) acrylic group-containing silane coupling agents; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane.

When the pressure-sensitive adhesive composition (I) contains a silane coupling agent, the amount is, for example, 5 parts by weight or less, 3 parts by weight or less, 1 part by weight or less, relative to 100 parts by weight of the polymer (A). It may be 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or even 0.05 parts by weight or less. The adhesive composition (I) may not contain a silane coupling agent.

Types of the pressure-sensitive adhesive composition (I) are, for example, emulsion type, solvent type (solution type), active energy ray-curable type (photocurable type), and heat-melting type (hot-melt type). From the viewpoint of forming a highly durable PSA sheet, the PSA composition (I) may be solvent-based, active energy ray-curable, or solvent-based. The solvent-based pressure-sensitive adhesive composition (I) may not contain a photocuring agent such as an ultraviolet curing agent.

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

[Adhesive sheet]
An example of the adhesive sheet of this embodiment is shown in FIG. The pressure-sensitive adhesive sheet 1 in FIG. 1 is a sheet formed from the pressure-sensitive adhesive composition (I).

The pressure-sensitive adhesive sheet 1 can have a radical generation amount RG ₁₀ within the range described above in the description of the pressure-sensitive adhesive composition (I). In addition, the pressure-sensitive adhesive sheet 1 has at least radical generation amounts _RG20 and _RG30 within the ranges described above in the description of the pressure-sensitive adhesive composition (I), and radical generation amount ratios _RG20 / _RG10 and _RG30 / _RG10 . It can have one property.

The pressure-sensitive adhesive sheet 1 can have a surface resistance value within the range described above in the description of the pressure-sensitive adhesive composition (I).

The adhesive sheet 1 can be formed from the adhesive composition (I) by the following method. For the solvent type, for example, the pressure-sensitive adhesive composition (I) or a mixture of the pressure-sensitive adhesive composition (I) and a solvent is applied to a base film to form a coating film, and the formed coating film is dried. An adhesive sheet 1 is formed. The pressure-sensitive adhesive composition (I) is thermally cured by heat during drying. For the active energy ray-curable type (photocurable type), for example, a monomer (group) that becomes the polymer (A) by polymerization, and, if necessary, a partial polymer of the monomer (group), a polymerization initiator , an additive, a solvent, and the like are applied to a substrate film, and the formed coating film is irradiated with an active energy ray to form an adhesive sheet 1 . The solvent may be removed by drying the coating film before irradiation with the active energy ray. The base film may be a film (release liner) whose coating surface has been subjected to a release treatment.

The adhesive sheet 1 formed on the base film can be transferred to any layer. Also, the base film may be an optical film such as a polarizing plate, in which case an optical laminate including the adhesive sheet 1 and the optical film is obtained.

A known method can be employed for application to the substrate film. Coating is, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, or the like. can be implemented by

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

Compositions and mixtures applied to the base film preferably have a viscosity suitable for handling and application. Therefore, for the active energy ray-curable type, the mixture to be applied preferably contains a partial polymer of the 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, and further 10 μm to 20 μm.

The adhesive sheet 1 can be used, for example, in optical laminates. In other words, the pressure-sensitive adhesive sheet 1 may be used for optical laminates. However, the application of the adhesive sheet 1 is not limited to the above examples.

[Optical laminate]
An example of the optical laminate of this embodiment is shown in FIG. The optical laminate 10A of FIG. 2 includes the adhesive sheet 1 and an optical film. The optical film in FIG. 1 is the polarizing plate 2 . The polarizing plate 2 contains a polarizer. The adhesive sheet 1 and the polarizing plate 2 are laminated together. The optical layered body 10A can be attached to an object (for example, an image display panel) with the adhesive sheet 1 interposed therebetween. The optical laminate 10A can be used as an optical film with an adhesive sheet, more specifically, as a polarizing plate with an adhesive sheet. Examples of optical films other than the polarizing plate 2 are retardation films and laminated films containing polarizing plates and/or retardation films. The optical film may be a circular polarizer. However, the optical film is not limited to the above examples. The optical film may include a film made of glass.

<Polarizing plate>
The polarizing plate 2 is typically a laminate containing a polarizer and a protective film (transparent protective film). The protective film is arranged, for example, in contact with the main surface of the polarizer (the surface with the widest area). A polarizer may be placed between two protective films. The optical laminate 10A may further include a protective film, and the protective film may be arranged on at least one surface of the polarizer.

The polarizer is not particularly limited. A uniaxially stretched film obtained by adsorbing a dichroic substance such as a dye; and a polyene-based oriented film such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. A polarizer typically consists of a polyvinyl alcohol film (the polyvinyl alcohol 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. The lower limit of the thickness of the polarizer is not particularly limited. A thin polarizer (for example, a thickness of 20 μm or less) is suppressed in dimensional change, and can contribute to an improvement in the durability of the optical layered body, especially at high temperatures.

As a material for the protective film, for example, a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, water barrier property, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic Polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof can be used. 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. For example, a protective film made of a thermoplastic resin is attached to one main surface of the polarizer via an adhesive, and a thermosetting resin or ultraviolet curable resin is attached to the other main surface of the polarizer. A protective film made of mold resin may be attached. The protective film may contain one or more optional additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants and the like.

The moisture permeability of the protective film is not particularly limited, and may be 200 g/(m ² ·day) or less, or may be 50 g/(m ² ·day) or less. In this case, moisture in the air can be prevented from entering the inside of the polarizing plate 2, and a change in the moisture content of the polarizing plate 2 can be suppressed. As a result, it is possible to prevent the polarizing plate 2 from curling or changing its dimension during storage or the like. In addition, a protective film whose moisture permeability is limited to the above range, when placed between the adhesive sheet 1 and the polarizer, can contribute to inhibition of movement of radicals from the adhesive sheet 1 at high temperatures. . Examples of materials for forming protective films with low moisture permeability include polyester-based polymers, polycarbonate-based polymers, arylate-based polymers, amide-based polymers, olefin-based polymers, cyclic olefin-based polymers, (meth)acrylic-based polymers, and these mixtures.

The moisture permeability of the protective film can be measured by the following method according to the moisture permeability test (cup method) of JIS Z0208:1976. First, the protective film is cut to a diameter of 60 mm to prepare a measurement sample. Next, a measurement sample is set in a moisture-permeable cup in which about 15 g of calcium chloride is placed. This moisture permeable cup is placed in a constant temperature machine set at a temperature of 40° C. and a humidity of 92% RH, and left for 24 hours to conduct a moisture permeability test. By measuring the amount of increase in the weight of calcium chloride before and after the test, the moisture permeability of the protective film can be determined.

Although the thickness of the protective film can be determined as appropriate, it is generally about 10 to 200 μm from the viewpoints of strength, workability such as handleability, and thinness.

The polarizer and the protective film are usually in close contact via a water-based adhesive or the like. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latexes, water-based polyurethanes, and water-based polyesters. Examples of adhesives other than the adhesives described above include ultraviolet curing adhesives, electron beam curing adhesives, and the like. Electron beam curing adhesives for polarizing plates exhibit suitable adhesion to various protective films. The adhesive may contain a metallic compound filler.

In the polarizing plate, a retardation film or the like can be formed on the polarizer instead of the protective film. It is also possible to provide another protective film, a retardation film, etc. on the protective film.

Regarding the protective film, a hard coat layer may be provided on the surface facing the surface adhered to the polarizer, and a treatment for the purpose of antireflection, antisticking, diffusion, antiglare, etc. may be applied. .

Another example of the optical laminate of this embodiment is shown in FIG. The optical layered body 10B of FIG. 3 has a layered structure in which a release liner 3, an adhesive sheet 1 and a polarizing plate 2 are layered in this order. By peeling off the release liner 3, the optical laminate 10B can be used as a polarizing plate with an adhesive sheet. Each of the examples below may be combined with each other unless they are technically inconsistent.

Materials constituting the release liner 3 include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; nets, foam sheets, metal foils, and laminates thereof. However, a plastic film is preferably used because of its excellent surface smoothness.

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

The thickness of the release liner 3 is usually about 5-200 μm, preferably about 5-100 μm. The release liner 3 may be subjected, if necessary, to silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agents, release and antifouling treatment using silica powder, etc., coating type, kneading type, vapor deposition. The mold may be subjected to antistatic treatment. In particular, by subjecting the surface of the release liner 3 to a release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., the releasability from the adhesive sheet 1 can be further enhanced.

As described above, the base film used in producing the pressure-sensitive adhesive sheet 1 may be used as the release liner 3 .

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

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

The retardation film 5 includes an antireflection retardation film (see JP 2012-133303 [0221], [0222], [0228]), a viewing angle compensation retardation film (JP 2012-133303 [ 0225], [0226]), an oblique orientation retardation film for viewing angle compensation (see JP-A-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 multiple layers, 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, even more preferably 1 to 9 μm, 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 a liquid crystal material is aligned and fixed.

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

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

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 layered body 10D and when the optical layered body 10D is incorporated in an image display device. Moreover, it may be a protective film 6 that functions as a window to an external space when incorporated in an image display device. 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, preferably polyester. However, the protective film 6 is not limited to the above example. 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 antiglare, antireflection, and antistatic.

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

The optical layered body of this embodiment can be distributed and stored, for example, as a wound body obtained by winding a band-shaped optical layered body, or as a sheet-shaped optical layered body. The optical layered body of the present embodiment is suitable for use in image display devices, particularly in-vehicle displays, which are used in environments where static electricity is particularly likely to occur. Examples of in-vehicle displays include panels for car navigation systems, cluster panels, and mirror displays. The cluster panel is a panel that displays the traveling speed of the vehicle, the number of revolutions of the engine, and the like.

[Image display panel]
An example of the image display panel of this embodiment is shown in FIG. The image display panel 11A of FIG. 6 includes an optical layered body 10A and further includes, for example, an image display cell 30A. Specifically, the optical laminate 10A is attached to the image display cell 30A with the adhesive sheet 1 interposed therebetween. The optical laminate 10B, 10C or 10D shown in FIGS. 3 to 5 can also be used instead of the optical laminate 10A (except for the release liner 3).

The image display cell 30A includes, for example, an image forming layer 32, a first transparent substrate 31 and a second transparent substrate 33. As shown in FIG. The image forming layer 32 is arranged, for example, between the first transparent substrate 31 and the second transparent substrate 33 and is in contact with the first transparent substrate 31 and the second transparent substrate 33 respectively. The adhesive sheet 1 of the optical laminate 10A is, for example, in contact with the first transparent substrate 31 of the image display cell 30A.

The image forming layer 32 is, for example, a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field. A liquid crystal layer containing such liquid crystal molecules is suitable for an IPS (In-Plane-Switching) method. However, the liquid crystal layer may be of TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, π type, VA (Vertical Alignment) type, or the like. In this specification, an image display cell provided with a liquid crystal layer is sometimes referred to as a liquid crystal cell, and an image display panel provided with a liquid crystal cell is sometimes referred to as a liquid crystal panel. Note that the image forming layer 32 may be an EL light 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 is sometimes referred to as a polymer film. Examples of polymers constituting the transparent substrate include polyethylene terephthalate, polycycloolefin, polycarbonate and the like. 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 30</b>A may further include layers other than the image forming layer 32 , the first transparent substrate 31 and the second transparent substrate 33 . Other layers include, for example, a color filter, an easy-adhesion layer and a hard coat layer. The color filter is arranged, for example, on the viewing side of the image forming layer 32, preferably between the first transparent substrate 31 and the adhesive sheet 1 of the optical layered body 10A. The easy-adhesion layer and the hard coat layer are arranged 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 laminate 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 the ground, it is easy to suppress the optical layered body 10A from being charged with static electricity. The conductive structure may cover the entire side surface of the optical layered body 10A, or may partially cover the side surface of the optical layered body 10A. The ratio of the area of the side surface of the optical layered body 10A covered with the conductive structure to the area of the entire side surface of the optical layered body 10A is, for example, 1% or more, preferably 3% or more.

Materials for the conductive structure include, for example, conductive pastes made of metals such as silver and gold; conductive adhesives; and other conductive materials. The conductive structure may be a wiring extending from the side surface of the optical layered body 10A.

The image display panel 11A may further include optical films other than the polarizing plate 2 . Examples of other optical films include films used in image display devices such as polarizing plates, reflectors, anti-transmissive plates, viewing angle compensation films, and brightness enhancement films. The image display panel 11A may include one or more of these optical films.

When the other optical film is a polarizing plate, the polarizing plate is attached to the second transparent substrate 33 of the image display cell 30A via an adhesive sheet, for example. This polarizing plate has, for example, the configuration described above for the polarizing plate 2 . In the 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 the material of the adhesive sheet for bonding the polarizing plate and the second transparent substrate 33 together, the materials 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, still more preferably 5 to 35 μm.

Another example of the image display panel of this embodiment is shown in FIG. The image display panel 11B of FIG. 7 further includes a conductive layer 40 arranged 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 mentioned 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 composite of various conductive agents such as carbon nanotubes, ITO, ATO, and a conductive polymer (for example, a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid). Bodies: 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/square to 1.0×10 ¹⁰ Ω/square, preferably 1.0×10 ⁸ Ω/square to 1.0×10 Ω/square. ⁹ Ω/square.

Another example of the image display panel of this embodiment is shown in FIG. The image display panel 11C of FIG. 8 includes an image display cell 30B that further includes a touch sensing electrode portion 35. As shown in FIG. The touch sensing electrode portion 35 is arranged between the first transparent substrate 31 and the second transparent substrate 33 in the image display cell 30B. The touch sensing electrode unit 35 has functions of touch sensor and touch drive. The image display panel 11C is a so-called in-cell image display panel, and the image display cell 30B is a so-called in-cell image display cell.

The touch sensing electrode section 35 has, for example, touch sensor electrodes 36 and touch drive electrodes 37 . The touch sensor electrode 36 means a (receiving) electrode for touch detection. The touch sensor electrodes 36 and the touch drive electrodes 37 can be independently formed in various patterns. For example, when the image display cell 30B has a flat plate shape, the touch sensor electrodes 36 and the touch drive electrodes 37 are provided independently in the X-axis direction and the Y-axis direction, respectively, and formed in a pattern in which they intersect at right angles. can be done. In FIG. 8 , in the touch sensing electrode portion 35 , the touch sensor electrodes 36 are arranged on the viewer side with respect to the touch drive electrodes 37 . However, the touch drive electrodes 37 may be arranged on the viewing side of the touch sensor electrodes 36 . In the touch sensing electrode section 35, the touch sensor electrodes 36 and the touch drive electrodes 37 may be integrated.

In FIG. 8, the touch sensing electrode portion 35 is arranged between the image forming layer 32 and the first transparent substrate 31 (on the viewer side of the image forming layer 32). However, the touch sensing electrode section 35 may be arranged between the image forming layer 32 and the second transparent substrate 33 (on the lighting system side of the image forming layer 32).

In the touch sensing electrode section 35, the touch sensor electrodes 36 and the touch drive electrodes 37 do not have to be in contact with each other. For example, the touch sensor electrodes 36 may be arranged between the image forming layer 32 and the first transparent substrate 31 and the touch drive electrodes 37 may be arranged between the image forming layer 32 and the second transparent substrate 33 .

A drive electrode (touch drive electrode 37 or an electrode in which the touch sensor electrode 36 and the touch drive electrode 37 are integrated) in the touch sensing electrode portion 35 can also serve as a common electrode for controlling the image forming layer 32 .

The touch sensor electrode 36 (capacitance sensor) and the touch drive electrode 37 that constitute the touch sensing electrode section 35, or an electrode formed by integrating these functions as a transparent conductive layer. The material of this transparent conductive layer is not particularly limited. alloys and the like. Materials for the transparent conductive layer may be oxides of metals such as indium, tin, zinc, gallium, antimony, zirconium, and 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, or the like, and particularly preferably ITO. When the material of the transparent conductive layer is ITO, the content of indium oxide in the transparent conductive layer is preferably 80 to 99% by weight and the content of tin oxide is preferably 1 to 20% by weight.

Electrodes (touch sensor electrodes 36, touch drive electrodes 37, or electrodes formed by integrating them) constituting the touch sensing electrode portion 35 are always placed between the first transparent substrate 31 and the second transparent substrate 33. It can be formed as a transparent electrode pattern by the method. This transparent electrode pattern is electrically connected to, for example, a lead wire formed at the end of the transparent substrate. The lead-out line is connected to, for example, the controller IC. As the shape of the transparent electrode pattern, any shape such as a comb shape, a stripe shape, a rhombus shape, or the like can be adopted according to 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.

[Image display device]
The image display device of this embodiment includes, for example, an image display panel 11A and an illumination system. Note that the image display panels 11B and 11C of FIGS. 7 and 8 can also be used instead of the image display panel 11A. In the image display device, the image display panel 11A is arranged, for example, on the viewing side of the lighting system. The illumination system has, for example, a backlight or a reflector, and irradiates the image display panel 11A with light.

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 applications, public information display (PID) applications, and the like, and is preferably an in-vehicle display.

The present invention will be described in more detail below with reference to examples. The 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). The Mw/Mn of the (meth)acrylic polymer was also measured in the same manner.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
・ Column: G7000H _XL + GMH _XL + GMH _XL manufactured by Tosoh Corporation
・Column size: 7.8 mmφ×30 cm each, 90 cm in total
・Column temperature: 40°C
・Flow rate: 0.8mL/min
・Injection volume: 100 μL
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
・Standard sample: Polystyrene

(Sample 1)
[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-hydroxybutyl acrylate was placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser. I prepared. Furthermore, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) as a polymerization initiator was added to 100 parts by weight of the monomer mixture together with 100 parts by weight of ethyl acetate. . While gently stirring the mixture, nitrogen gas was introduced into the flask to replace it with nitrogen. A solution of (meth)acrylic polymer A1 having a weight average molecular weight (Mw) of 1,800,000 and Mw/Mn of 4.4 was prepared by conducting a polymerization reaction for 8 hours while maintaining the liquid temperature in the flask at around 55°C. bottom.

[Preparation of (meth)acrylic pressure-sensitive adhesive composition]
Next, 0.35 parts by weight of an isocyanate-based cross-linking agent (Coronate L; trimethylolpropane tolylene diisocyanate, manufactured by Tosoh Corporation), 0.35 parts by weight per 100 parts by weight of the solid content of the solution of the (meth)acrylic polymer A1. 01 parts by weight of a peroxide cross-linking agent (Niper BMT, manufactured by NOF Corporation) and 5 parts by weight of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI; manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) as a conductive agent are further blended. Thus, a solution of a (meth)acrylic pressure-sensitive adhesive composition (Sample 1) was prepared.

(Sample 2)
A solution of the pressure-sensitive adhesive composition (Sample 2) was prepared in the same manner as for Sample 1, except that no peroxide-based cross-linking agent was added.

(Sample 3)
A solution of the pressure-sensitive adhesive composition (Sample 3) was prepared in the same manner as for Sample 1, except that the amount of the peroxide-based cross-linking agent was changed to 0.1 parts by weight.

(Sample 4)
(Meth) With respect to 100 parts by weight of the solid content of the acrylic polymer A1 solution, except that 1.0 parts by weight of an antioxidant (Irganox 1135, manufactured by BASF Japan) was further added, By the same method as in sample 3, A solution of the adhesive composition (Sample 4) was prepared.

(Sample 5)
A solution of the pressure-sensitive adhesive composition (Sample 5) was prepared in the same manner as for Sample 1, except that the amount of the peroxide-based cross-linking agent was changed to 1.0 parts by weight.

The composition of each pressure-sensitive adhesive composition of Samples 1-5 is shown in Table 1 below.

[Production of adhesive sheet]
A 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, and the thickness of the adhesive sheet after drying was 20 μm. was applied as follows. The obtained coating film was dried at 155° C. for 1 minute to form an adhesive sheet (Samples 11 to 15 corresponding to each of Samples 1 to 5) on the surface of the release liner.

<Quantification of amount of radicals generated>
For each PSA composition, the radical generation amounts RG ₁₀ , RG ₂₀ and RG ₃₀ when forming PSA sheets were evaluated by the methods described above. However, the test piece (approximately 50 mg) housed in the ESR sample tube was taken from the pressure-sensitive adhesive sheet produced above. The measurement apparatus and measurement conditions were as described below. The g value (central magnetic field) of the ESR signal used to calculate the amount of radicals generated was the strongest ESR signal among the radicals generated due to the polyether structure in the side chain of the (meth)acrylic polymer A1. It was set to around 3352 G (gauss) corresponding to NO (nitroxide) radicals, which are large and considered to greatly contribute to the polyene conversion of PVA contained in the polarizing plate.
・Measuring device: EMXplus (BRUKER)
・Measurement conditions Measurement temperature 105℃
Magnetic field sweep range 200G
Modulation 100kHz, 5G
Microwave 9.40GHz, 1mW
Sweep time 80 seconds x 4 times Time constant 327.68 milliseconds Number of data points 1000 points
Cavity Super-high-Q

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

[Preparation of optical laminate]
<Preparation of polarizing plate A>
A polyvinyl alcohol film having a thickness of 80 μm was stretched up to 3 times while being dyed in an iodine solution having a concentration of 0.3% by weight at a temperature of 30° C. for 1 minute between rolls having different speed ratios. Next, while being immersed in an aqueous solution containing boric acid at a concentration of 4% by weight and potassium iodide at a concentration of 10% by weight at a temperature of 60° C. for 0.5 minutes, it is stretched to a total draw ratio of 6 times. bottom. Next, after washing by immersing for 10 seconds in an aqueous solution containing potassium iodide at a concentration of 1.5% by weight at a temperature of 30° C. and drying at 50° C. for 4 minutes, a polarizer having a thickness of 28 μm was obtained. Obtained. A 30-μm-thick transparent protective film made of a modified acrylic polymer having a lactone ring structure was attached to one side of the polarizer with a polyvinyl alcohol-based adhesive. Furthermore, a transparent protective film having a thickness of 47 μm, which is a triacetyl cellulose film (KC4UY manufactured by Konica Minolta, KC4UY) formed with a hard coat layer (HC), was attached to the other surface of the polarizer with a polyvinyl alcohol-based adhesive. A polarizing plate A was prepared by heat drying for 5 minutes in an oven set at 70°C.

<Preparation of polarizing plate B>
A polarizer having a thickness of 18 μm was obtained in the same manner as in the preparation of the polarizing plate A, except that the thickness of the polyvinyl alcohol film used in the preparation of the polarizer was changed. Next, two types of transparent protective films were attached to the obtained polarizer in the same manner as in the preparation of the polarizing plate A to prepare a polarizing plate B.

(Example 1)
The adhesive sheet of Sample 11 formed on the release liner was transferred to the above polarizing plate B (polarizer thickness: 18 μm) to prepare the optical laminate of Example 1 (polarizing plate with adhesive sheet). The adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of the modified acrylic polymer.

(Example 2)
An optical laminate of Example 2 was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive sheet of Sample 12 was used instead of Sample 11.

(Example 3)
An optical laminate of Example 3 was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive sheet of Sample 13 was used instead of Sample 11.

(Example 4)
An optical laminate of Example 4 was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive sheet of Sample 14 was used instead of Sample 11.

(Example 5)
An optical laminate of Example 5 was produced in the same manner as in Example 1, except that the adhesive sheet of Sample 13 was used instead of Sample 11 and the polarizing plate A was used instead of polarizing plate B.

(Comparative example 1)
An optical laminate of Comparative Example 1 was produced in the same manner as in Example 1, except that the pressure-sensitive adhesive sheet of Sample 15 was used instead of Sample 11.

<Coloring>
The coloring of the optical layered body under high temperature was evaluated by the following method. The produced optical layered body was cut into a size of 45×40 mm so that the absorption axis of the polarizer was on the long side. Next, the cut optical layered body was attached to a glass plate imitating the outermost layer of an image display panel via the adhesive sheet. Next, a glass plate imitating a front transparent member was placed on the exposed surface of the optical laminate on the polarizing plate side via an adhesive (manufactured by Nitto Denko Corporation, LUCIACS CS9821; acrylic acid monomer-free adhesive, thickness 200 μm). By sticking together, a laminate for evaluation imitating an image display device was produced. Next, a heating test was performed in which the laminate for evaluation was placed in a hot air oven maintained at 95° C. or 105° C. for 120 hours, and the light transmittance in the thickness direction of the laminate was measured before and after the heating test. The light transmittance was determined as a Y value (performing visibility correction) by a two-degree field of view XYZ system defined in JlS Z8701:1982 using a spectrophotometer (LPF-200, manufactured by Otsuka Electronics Co., Ltd.). A C light source was used as the light source. The measurement wavelength was 380 to 700 nm (every 10 nm). The light transmittance of the laminate was measured near the center where the coloration was considered to be the most advanced. Assuming that the light transmittance before the heat test is Ts ₀ and the light transmittance after the heat test is Ts ₁₂₀ , the degree of coloring of the optical layered body at high temperatures is evaluated based on the difference ΔTs=Ts ₁₂₀ -Ts ₀ . bottom.
A: ΔTs is over 0% B: ΔTs is 0% or less -3% or more C: ΔTs is -3% or less -10% or more D: ΔTs is -10% or less

<Durability (high temperature durability)>
The durability (high temperature durability) of the optical laminate was evaluated by the following method. The produced optical layered body was fixed to the surface of a glass plate (Eagle XG manufactured by Corning) via the adhesive sheet. Fixation was performed in an atmosphere of 24° C. and 50% RH. Next, after treatment in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes, it was allowed to stand until it cooled to 24°C to stabilize the bonding of the optical laminate to the glass plate, followed by heating at 105°C. It was left in a heated atmosphere for 500 hours. After standing, the atmosphere was returned to 24° C. and 50% RH, and the polarizing plate was visually checked for peeling from the glass plate and bubbles between the glass plate and the polarizing plate. , to evaluate the durability.
A: No change in appearance such as foaming or peeling is observed.
B: Single peeling or foaming is slightly observed at the edge, but within a practically acceptable range.
C: Slight continuous peeling or foaming is observed at the edge, but within a practically acceptable range.
D: Significant peeling or foaming is observed at the edge, which is problematic in practice.

The evaluation results of each optical layered body of Examples and Comparative Examples are shown in Table 2 below together with the evaluation results of the pressure-sensitive adhesive sheet used in each optical layered body. Note that the coloring (reddening) in each optical layered body at high temperatures mainly occurred in the polarizer.

As shown in Table 2, in the optical layered bodies of Examples, the pressure-sensitive adhesive sheet achieved a lower surface resistance value than the optical layered bodies of Comparative Examples, while suppressing coloration at high temperatures.

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

1 adhesive sheet 2 polarizing plate 10A, 10B, 10C, 10D optical laminate 11A, 11B, 11C image display panel

Claims (20)

Containing a polymer (A) having a polyether structure as a main component,
further comprising a conductive agent;
The polymer (A) has a structural unit derived from a monomer represented by 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 branched, and n is 1 to 15. is an integer and
A pressure-sensitive adhesive composition, wherein when the pressure-sensitive adhesive sheet is formed, the pressure-sensitive adhesive sheet has a radical generation rate RG ₁₀ of 1.5×10 ¹⁴ radicals/g or less and a surface resistance value of 1×10 ¹⁰ Ω/□ or less.
However, the RG ₁₀ is the amount of radicals generated from the pressure-sensitive adhesive sheet when heated at 105° C. for 10 minutes, as evaluated by an electron spin resonance method. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the content of said structural unit in said polymer (A) is 25% by weight or more. 3. The pressure-sensitive adhesive composition according to claim 1, wherein the surface resistance value is 1*10 ^< 9 > [Omega]/square or less. 4. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, 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 from the pressure-sensitive adhesive sheet when heated at 105° C. for 20 minutes as evaluated by electron spin resonance method. 5. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the radical generation amount ratio RG ₃₀ /RG ₁₀ is less than 1.9.
However, the RG ₃₀ is the amount of radicals generated from the pressure-sensitive adhesive sheet when heated at 105° C. for 30 minutes as evaluated by electron spin resonance method. The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the amount of the conductive agent in the pressure-sensitive 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 according to any one of claims 1 to 6, further comprising an isocyanate-based cross-linking agent. The pressure-sensitive adhesive composition according to any one of claims 1 to 7, further comprising a peroxide-based cross-linking agent. The pressure-sensitive adhesive composition according to any one of claims 1 to 8, which is solvent-based. 10. The pressure-sensitive adhesive composition according to any one of claims 1 to 9, which is used for optical laminates. The pressure-sensitive adhesive composition contains a polymerization initiator for forming the polymer (A), and the polymerization initiator contains at least one selected from the group consisting of a thermal polymerization initiator and a photopolymerization initiator. The adhesive composition according to any one of claims 1-10. The pressure-sensitive adhesive composition according to claim 11, wherein the polymerization initiator contains at least one selected from the group consisting of an azo polymerization initiator, a peroxide polymerization initiator, and a redox polymerization initiator. The photopolymerization initiator includes a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, Claim 11, comprising at least one selected from the group consisting of a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. Or the pressure-sensitive adhesive composition according to 12. A pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 13. The pressure-sensitive adhesive sheet according to claim 14;
an optical film;
An optical stack comprising: 16. The optical laminate according to claim 15, wherein the optical film is a polarizing plate containing a polarizer. further comprising a protective film;
17. The optical laminate according to claim 16, wherein the protective film is arranged on at least one surface of the polarizer. 18. The optical laminate according to claim 16 or 17, wherein the polarizer has a thickness of 20 [mu]m or less. An image display panel comprising the optical laminate according to any one of claims 15 to 18. An image display device comprising the image display panel according to claim 19 .

Images