Optical laminate, image display panel, and image display device

Abstract

Provided is an optical laminate which is more suitable for suppressing display defects. The optical laminate includes an adhesive sheet and an optical film. The adhesive sheet is formed from an adhesive composition containing a polymer (A) and an antistatic agent. The surface resistivity of the adhesive sheet side of the optical laminate at-15 DEG C is 1.0 * 1010 [Omega] / square or less. The glass transition temperature of the polymer (A) calculated according to the FOX equation may be less than-55 DEG C. The adhesive sheet may have a relative dielectric constant of 1000 or more at a frequency of 100 Hz.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical laminate, an image display panel, and an image display device. BACKGROUND

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) are rapidly spreading. The above-described various image display devices have, for example, an image display unit such as a liquid crystal cell, an EL light-emitting element, and a laminated structure of an optical laminate including a polarizing plate and an adhesive sheet. The adhesive sheet is mainly used for the joining between the films contained in the optical laminate and the joining between the image display unit and the optical laminate.

[0003] For the image display device, static electricity is generated at the time of manufacturing (for example, when the optical laminate is attached to the image display unit via the adhesive sheet) or at the time of use (for example, when a user touches the image display device). If the image display device is charged due to the static electricity, display failure and the like can occur. Patent Literature 1 discloses that an antistatic agent is contained in the adhesive sheet.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2020-180305 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] According to the research by the present inventors and the like, from the viewpoint of sufficiently preventing display failure of the image display device, there is room for improvement in the optical laminate. Therefore, an object of the present application is to provide an optical laminate more suitable for suppressing display failure.

[0009] MEANS OF SOLVING THE PROBLEM

[0010] The present inventors and the like found that display failure of the image display device is likely to occur in a low-temperature environment, and completed the present application based on this finding.

[0011] The present application provides an optical laminate including an adhesive sheet and an optical film,

[0012] The above-described adhesive sheet is formed of an adhesive composition including a polymer (A) and an antistatic agent,

[0013] The surface resistivity of the above-described adhesive sheet side of the above-described optical laminate at -15°C is 1.0 x 10 10 Ω / □ or less.

[0014] Further, the present application provides an image display panel including the optical laminate described above.

[0015] Further, the present application provides an image display device including the image display panel described above.

[0016] Effects of the Invention

[0017] According to the present application, an optical laminate more suitable for suppressing display failure in a low-temperature environment can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a cross-sectional view schematically showing one example of the optical laminate of the present embodiment.

[0019] Figure 2 is a cross-sectional view schematically showing another example of the optical laminate of the present embodiment.

[0020] Figure 3 is a cross-sectional view schematically showing one example of the image display panel of the present embodiment.

[0021] Figure 4 is a cross-sectional view schematically showing another example of the image display panel of the present embodiment.

[0022] Figure 5 is a cross-sectional view schematically showing another example of the image display panel of the present embodiment. DETAILED DESCRIPTION

[0023] The optical laminate of the first aspect of the present application includes an adhesive sheet and an optical film,

[0024] The adhesive sheet described above is formed of an adhesive composition including a polymer (A) and an antistatic agent,

[0025] The surface resistivity of the adhesive sheet described above of the optical laminate described above at -15°C is 1.0 x 10 10 Ω / □ or less.

[0026] In the second aspect of the present application, for example, in the optical laminate of the first aspect, the glass transition temperature of the polymer (A) calculated according to the FOX formula is less than -55°C, and the relative dielectric constant of the adhesive sheet at a frequency of 100 Hz is 1000 or more.

[0027] In the third aspect of the present application, for example, in the optical laminate of the first or second aspect, the saturated moisture content of the adhesive sheet in an environment of 23°C and 55% RH is 2.0% by weight or less.

[0028] In the fourth aspect of the present application, for example, in the optical laminate described in any one of the first to third aspects, the saturation moisture content of the adhesive sheet in an environment of 85°C and 85% RH is 5.0% by mass or less.

[0029] In the fifth aspect of the present application, for example, in the optical laminate described in any one of the first to fourth aspects, the antistatic agent contains an organic cation salt.

[0030] In the sixth aspect of the present application, for example, in the optical laminate described in any one of the first to fifth aspects, the polymer (A) is a (meth)acrylic polymer.

[0031] In the seventh aspect of the present application, for example, in the optical laminate described in any one of the first to sixth aspects, the polymer (A) has a polyether structure.

[0032] In the eighth aspect of the present application, for example, in the optical laminate described in any one of the first to seventh aspects, the polymer (A) has a structural unit derived from a monomer represented by formula (1).

[0033] [Chemical Formula 1]

[0034]

[0035] In the above formula (1), R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl group which can be linear or branched, and n is an integer of 1 to 15.

[0036] In the ninth aspect of the present application, for example, in the optical laminate of the eighth aspect, in the above formula (1), n is an integer of 2 to 15.

[0037] In the tenth aspect of the present application, for example, in the optical laminate described in any one of the first to ninth aspects, the adhesive composition further contains a peroxide crosslinking agent and a radical scavenger.

[0038] In the eleventh aspect of the present application, for example, in the optical laminate of the tenth aspect, the radical scavenger is an antioxidant.

[0039] In the twelfth aspect of the present application, for example, in the optical laminate described in any one of the first to eleventh aspects, the adhesive composition further contains an isocyanate crosslinking agent.

[0040] The image display panel of the thirteenth aspect of the present application is provided with the optical laminate described in any one of the first to twelfth aspects.

[0041] The image display device of the 14th aspect of the present application includes the image display panel of the 13th aspect.

[0042] The present application will be described in detail below, but the present application is not limited to the following embodiments, and can be arbitrarily modified and implemented within the scope of the gist of the present application.

[0043] The optical laminate of the present embodiment includes an adhesive sheet and an optical film. The adhesive sheet is formed of an adhesive composition (I) including a polymer (A) and an antistatic agent. The surface resistivity of the adhesive sheet at -15°C is 1.0 x 10 10 Ω / □ or less.

[0044] [Optical laminate]

[0045] Figure 1 is a cross-sectional view schematically showing an example of the optical laminate of the present embodiment. The optical laminate 10A includes an adhesive sheet 1 and an optical film 2. The adhesive sheet 1 and the optical film 2 are laminated with each other. The optical laminate 10A can be attached to an object (for example, an image display panel) via the adhesive sheet 1.

[0046] The adhesive sheet 1 is formed on the optical film 2, for example. The adhesive sheet 1 is formed in contact with the optical film 2. The adhesive sheet 1 is formed on one principal surface of the optical film 2. In the present specification, the "principal surface" refers to a surface having the largest area of a film or a layer. Figure 1 In the present embodiment, the adhesive sheet 1 is formed on the entire one principal surface of the optical film 2. However, the adhesive sheet 1 can be formed only on a part of the one principal surface of the optical film 2. In the present specification, the "principal surface" refers to a surface having the largest area of a film or a layer.

[0047] [Adhesive sheet]

[0048] The surface resistivity R of the adhesive sheet 1 side of the optical laminate 10A at -15°C is 1.0 x 10 10 Ω / □ or less. By providing the optical laminate 10A with the adhesive sheet 1 having a surface resistivity R of 1.0 x 10 10 Ω / □ or less, display failure caused by charging of the image display device can be suppressed even in a low-temperature environment.

[0049] The surface resistivity R can be 7.0 x 10 9 Ω / □ or less, 5.0 x 10 9 Ω / □ or less, 3.0 x 10 9 Ω / □ or less, 2.0 x 10 9 Ω / □ or less, and further 5.0 x 10 8 Ω / □ or less. The lower limit value of the surface resistivity R is, for example, 1.0 x 10 6 Ω / □, and can be 1.0 x 10 7Ω / □ or more, further preferably 1.0 x 10 6 Ω / □ or more, further preferably 1.0 x 10 7 Ω / □ or more. The surface resistivity R can be measured, for example, using a high resistance resistivity meter (as an example, Hiresta series manufactured by MITSUBISHI CHEMICAL ANALYTECH) under the conditions of an applied voltage of 250 V and an applied time of 10 seconds.

[0050] The surface resistivity R1 of the adhesive sheet 1 side of the optical laminate 10A at 25°C is, for example, 1.0 x 10 10 Ω / □ or less. The surface resistivity R1 is, for example, 1.0 x 10 9 Ω / □ or less, 8.0 x 10 8 Ω / □ or less, 6.0 x 10 8 Ω / □ or less, 5.0 x 10 8 Ω / □ or less, 3.0 x 10 8 Ω / □ or less, 2.0 x 10 8 Ω / □ or less, 1.0 x 10 8 Ω / □ or less, further 8.0 x 10 7 Ω / □ or less. The lower limit value of the surface resistivity R1 is, for example, 1.0 x 10 6 Ω / □ or more, 1.0 x 10 7 Ω / □.

[0051] The surface resistivity of the adhesive sheet 1 side of the optical laminate 10A does not easily increase even in, for example, a low temperature environment. The ratio R / R1 of the surface resistivity R (Ω / □) of the adhesive sheet 1 side of the optical laminate 10A at -15°C to the surface resistivity R1 (Ω / □) of the adhesive sheet 1 side of the optical laminate 10A at 25°C is, for example, 50.0 or less, can be 40.0 or less, 30.0 or less, 20.0 or less, 15.0 or less, 10.0 or less, 8.0 or less, further 5.0 or less. The lower limit value of the ratio R / R1 is, for example, 0.1, can be 0.5, further 1.0. In the case where the ratio R / R1 is 50.0 or less, display failure can be further suppressed.

[0052] As described above, the surface resistivity of the adhesive sheet 1 side of the optical laminate 10A at -15°C is 1.0 x 10 10Ω / □. Thus, the optical laminate 10A can suppress display failure caused by charging of the image display device even in a low-temperature environment. Further, the optical laminate 10A exerts an effect of being able to suppress reduction in the sensitivity of the touch sensor in addition to the above-described effects by appropriately adjusting the saturated moisture content of the adhesive sheet 1 under given conditions.

[0053] The saturated moisture content of the adhesive sheet 1 in an environment of 23°C and 55% RH, Ab1, is, for example, 2.0% by weight or less. By making the saturated moisture content of the adhesive sheet 1, Ab1, 2.0% by weight or less, it is possible to suppress an increase in the electrical conductivity after the humidification test. Thus, it is possible to suppress reduction in the sensitivity of the touch sensor. The saturated moisture content Ab1may be 1.5% by weight or less, or 1.0% by weight or less. The lower limit of the saturated moisture content Ab1is, for example, 0.5% by weight.

[0054] The saturated moisture content of the adhesive sheet 1 in an environment of 85°C and 85% RH, Ab2, is, for example, 5.0% by weight or less. By making the saturated moisture content of the adhesive sheet 1, Ab2, 5.0% by weight or less, it is possible to suppress reduction in the sensitivity of the touch sensor under high-temperature high-humidity conditions. The saturated moisture content Ab2may be 4.0% by weight or less, or 3.0% by weight or less. The lower limit of the saturated moisture content Ab2is, for example, 2.0% by weight.

[0055] The adhesive sheet 1 is formed of the adhesive composition (I) containing the polymer (A) and the antistatic agent.

[0056] < POLYMER (A) >

[0057] Examples of the polymer (A) are (meth)acrylic polymers, urethane polymers, silicone polymers, and rubber polymers. The polymer (A) can have a polyether structure. The polymer (A) is preferably a (meth)acrylic polymer. In other words, the adhesive composition (I) can contain a (meth)acrylic polymer as a main component. In further words, the adhesive composition (I) can be an acrylic adhesive composition. The main component refers to a component having the highest content by weight in the composition. The content of the main component is, for example, 50% by weight or more, can be 60% by weight or more, 70% by weight or more, 75% by weight or more, and further can be 80% by weight or more. In the present specification, the "(meth)acrylic polymer" refers to a polymer having a structural unit derived from a (meth)acrylic monomer such as a (meth)acrylate. The content of the structural unit derived from the (meth)acrylic monomer in the (meth)acrylic polymer is, for example, 40% by weight or more, can be 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, and further can be 95% by weight or more. The (meth)acrylic polymer can contain only the structural unit derived from the (meth)acrylic monomer. In the present specification, the "(meth)acrylic acid" refers to acrylic acid and methacrylic acid. The "(meth)acrylate" refers to an acrylate and a methacrylate.

[0058] The polymer (A) can have a polyether structure. The polyether structure is a structure containing at least two ether groups (-O-). The polyether structure can be linear or can have a branched chain. An example of the polyether structure contains an alkyl group, which is optionally linear or has a branched chain, and at least two ether groups. The polymer (A) can have a polyether structure in the main chain or can have a polyether structure in the side chain, and preferably has a polyether structure in the side chain. The polymer (A) can be a (meth)acrylic polymer having a polyether structure in the side chain.

[0059] The polymer (A) can have a structural unit having a polyether structure. In the structural unit, the polyether structure can be located in the main chain or can be located in the side chain, and preferably is located in the side chain. The polymer (A) can have a structural unit derived from a (meth)acrylic monomer having a polyether structure in the side chain.

[0060] The polymer (A) having a polyether structure in the side chain contains, for example, a structural unit derived from a monomer (A1) represented by formula (1) below. R 1 is a hydrogen atom or a methyl group. R 2 is an alkyl group, which can be linear or can have a branched chain, and is preferably a linear alkyl group. The number of carbon atoms of the alkyl group can be 1 to 10, and further can be 1 to 4. R 2Examples of R are methyl and ethyl. n is, for example, an integer of 1 to 15, preferably an integer of 1 to 10, more preferably an integer of 1 to 5. As appropriate, n can be an integer of 2 to 15, an integer of 2 to 10, or an integer of 2 to 5. When n is 1, the monomer (A1) contains "-O-" of the COO group, and contains two ether groups. When n is 2, the monomer (A1) contains "-O-" of the COO group, and contains three ether groups. The monomer (A1) is one of (meth)acrylic monomers, more specifically, one of (meth)acrylate monomers. If R 2 O group at the end of the side chain, the monomer (A1) is also one of alkoxyl group-containing (meth)acrylate monomers. The structural unit derived from the monomer (A1) has a polyether structure in the side chain.

[0061] [Chemical Formula 2]

[0062]

[0063] Examples of the monomer (A1) are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate, preferably at least one selected from the group consisting of 2-(2-ethoxyethoxy)ethyl acrylate (CBA) and 2-methoxyethyl acrylate (MEA), more preferably 2-(2-ethoxyethoxy)ethyl (meth)acrylate (CBA). The structural unit derived from the monomer (A1) is particularly effective in reducing the surface resistivity of the adhesive sheet formed from the adhesive composition (I). In addition, the structural unit derived from the monomer (A1) can contribute to the reduction of the glass transition temperature (Tg) of the polymer (A). Furthermore, by having the polymer (A) have the structural unit derived from the monomer (A1), the increase in the electrical conductivity after the humidity test can be suppressed. Thereby, the reduction in the sensitivity of the touch sensor provided in the image display device can be suppressed.

[0064] The content ratio of the structural unit having a polyether structure (for example, the structural unit derived from the monomer (A1)) in the polymer (A) is, for example, 0% by mass or more, can be 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, and further can be 50% by mass or more. The upper limit of the content ratio is, for example, 100% by mass or less, can be 90% by mass or less, 80% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, and further can be less than 60% by mass.

[0065] In the case where n is an integer of 2 to 15 in monomer (A1), the content ratio of the structural unit derived from monomer (A1) in polymer (A) is, for example, 0% by weight or more, and can be 10% by weight or more, 15% by weight or more, 20% by weight or more, 30% by weight or more, and further can be 40% by weight or more. The upper limit of the content ratio is, for example, 80% by weight, and can be 70% by weight or less, 60% by weight or less, and further can be 55% by weight or less.

[0066] Polymer (A) can have one or two or more structural units derived from monomer (A2). Note that the monomers (A2) shown below can be copolymerized with monomer (A1).

[0067] Examples of monomer (A2) are (meth)acrylic monomers having an alkyl group with 1 to 30 carbon atoms in the side chain. The alkyl group can be linear or branched. Examples of (meth)acrylic monomers having an alkyl group in the side chain are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-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 (EHA), 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 ((meth)acrylate lauryl ester), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, and stearyl (meth)acrylate. The content ratio of the structural unit derived from (meth)acrylic monomers having an alkyl group in the side chain in polymer (A) is, for example, 5% by weight or more and 80% by weight or less. The content ratio of the structural unit derived from (meth)acrylic monomers having an alkyl group in the side chain in polymer (A) can be 70% by weight or less, 60% by weight or less, 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, and further can be 5% by weight or less. Optionally, the content ratio of the structural unit derived from (meth)acrylic monomers having an alkyl group in the side chain in polymer (A) can be 0% by weight (polymer (A) can not have the structural unit).

[0068] Other examples of monomer (A2) are hydroxyl group-containing monomers. The hydroxyl group-containing monomer can be a hydroxyl group-containing (meth)acrylic monomer. Examples of the hydroxyl group-containing monomer are (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 3-hydroxypropyl ester, (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid 6-hydroxyhexyl ester, (meth)acrylic acid 8-hydroxyoctyl ester, (meth)acrylic acid 10-hydroxydecyl ester, and (meth)acrylic acid 12-hydroxy lauryl ester, and the like (hydroxyalkyl (meth)acrylate), and (4-hydroxymethylcyclohexyl)methyl acrylate. From the viewpoint of improving the durability of the adhesive sheet formed from the adhesive composition (I), (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 4-hydroxybutyl ester are preferred, and (meth)acrylic acid 4-hydroxybutyl ester is more preferred. The content of the structural unit derived from the hydroxyl group-containing monomer in the polymer (A) is, for example, 1 to 5% by weight, can be 3% by weight or less, and further can be 2% by weight or less. The polymer (A) can also have no structural unit derived from the hydroxyl group-containing monomer.

[0069] The monomer (A2) can be an aromatic ring-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an amide group-containing monomer. The aromatic ring-containing monomer can be an aromatic ring-containing (meth)acrylic monomer. Examples of the aromatic ring-containing monomer are phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, oxirane-modified nonylphenol (meth)acrylate, hydroxyethylated β-naphthol (meth)acrylate, and diphenyl (meth)acrylate. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the amino group-containing monomer are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer are 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-hydroxymethyl (meth)acrylamide, N-hydroxymethyl-N-propyl (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, and mercaptoethyl (meth)acrylamide, and the like (acrylamide-based monomer); N-(meth)acryloyl morpholine, N-(meth)acryloyl piperidine, and N-(meth)acryloyl pyrrolidine, and the like (N-acryloyl heterocyclic monomer); and N-vinyl pyrrolidone and N-vinyl-ε-caprolactam, and the like (N-vinyl-containing lactam-based monomer).

[0070] The monomer (A2) can be a multifunctional monomer. Examples of the multifunctional monomer 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, epoxy acrylate, polyester acrylate, urethane acrylate, and the like multifunctional acrylates; and divinylbenzene. The multifunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate.

[0071] The total content of the structural units derived from the aromatic ring-containing monomer, the carboxyl group-containing monomer, the amino group-containing monomer, the amide group-containing monomer, and the multifunctional monomer in the polymer (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and further preferably 8% by weight or less. When the polymer (A) has these structural units, the total content thereof is, for example, 0.01% by weight or more, and can be 1% by weight or more, 2% by weight or more, and further can be 3% by weight or more. The polymer (A) can not have these structural units. In particular, in the polymer (A), the content of the structural unit derived from the carboxyl group-containing monomer can be less than 0.1% by weight, and can be 0% by weight (the structural unit can not be present).

[0072] Examples of the other monomer (A2) are acrylonitrile, (meth)acrylonitrile, and the like nitrile group-containing (meth)acrylates; glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and the like epoxy group-containing monomers; sodium vinyl sulfonate and the like sulfonic acid group-containing monomers; phosphonic acid group-containing monomers; cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and the like (meth)acrylates having an alicyclic hydrocarbon group; vinyl acetate, vinyl propionate, and the like vinyl esters; styrene, vinyltoluene, and the like aromatic vinyl compounds; ethylene, propylene, butadiene, isoprene, isobutylene, and the like olefins or dienes; vinyl alkyl ethers; and vinyl chloride.

[0073] The total content of the structural units derived from the above-described other monomer (A2) in the polymer (A) is, for example, 30% by weight or less, can be 10% by weight or less, and is preferably 0% by weight (the structural unit is not present).

[0074] The polymer (A) can be formed by polymerizing one or more of the above-described monomers using a known method. The monomers can also be polymerized with a partial polymer of the monomers. The polymerization can be performed by, for example, solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of being able to form an adhesive sheet having excellent optical transparency, solution polymerization or active energy ray polymerization is preferred. The polymerization is preferably performed while avoiding contact of the monomers and / or the partial polymer with oxygen, and for this purpose, polymerization in an atmosphere of an inert gas such as nitrogen, or polymerization in a state in which oxygen is blocked by a resin film or the like can be employed. The polymer (A) to be formed can be in any form such as a random copolymer, a block copolymer, or a graft copolymer.

[0075] The polymerization system for forming the polymer (A) can contain one or more polymerization initiators. The type of the polymerization initiator can be selected according to the polymerization reaction, and can be, for example, a thermal polymerization initiator or a photopolymerization initiator.

[0076] The solvent used in the solution polymerization is, for example, an ester such as ethyl acetate or n-butyl acetate; an aromatic hydrocarbon such as toluene or benzene; an aliphatic hydrocarbon such as n-hexane or n-heptane; an alicyclic hydrocarbon such as cyclohexane or methylcyclohexane; a ketone such as methyl ethyl ketone or methyl isobutyl ketone, but the solvent is not limited to the above examples. The solvent can be a mixed solvent of two or more solvents.

[0077] The polymerization initiator used in the solution polymerization is, for example, an azo-based polymerization initiator, a peroxide-based polymerization initiator, or a redox-based polymerization initiator. The peroxide-based polymerization initiator is, for example, dibenzoyl peroxide or t-butyl peroxy maleate. Among them, an azo-based polymerization initiator disclosed in Japanese Patent Application Publication No. 2002-69411 is preferred. The azo-based polymerization initiator is, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-methylpropionic acid) dimethyl ester, or 4,4'-azobis(4-cyanopentanoic acid), but the polymerization initiator is not limited to the above examples. The amount of the azo-based polymerization initiator is, for example, 0.05 to 0.5 parts by weight, or 0.1 to 0.3 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

[0078] The active energy ray used in the active energy ray polymerization is, for example, an ionizing ray such as an α-ray, a β-ray, a γ-ray, a neutron ray, an electron ray, or an ultraviolet ray. The active energy ray is preferably an ultraviolet ray. Polymerization using ultraviolet ray irradiation is also referred to as photopolymerization. The polymerization system for active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for active energy ray polymerization are not limited as long as the polymer (A) can be formed.

[0079] The photopolymerization initiator is not limited to the above examples, and examples of the photopolymerization initiator include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-keto alcohol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzil photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, and the like.

[0080] Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and benzoin methyl ether. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(tert-butyl)dichloroacetophenone. Examples of the α-keto alcohol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl oxime). Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzil photopolymerization initiator include benzil. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexyl phenyl ketone. Examples of the ketal photopolymerization initiator include benzil dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0081] The photopolymerization initiator is used in an amount of, for example, 0.01 to 1 parts by weight, and also in an amount of 0.05 to 0.5 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

[0082] The weight average molecular weight (Mw) of the polymer (A) is, for example, 1 to 30 million, and preferably 1.8 to 30 million. By setting the weight average molecular weight of the polymer (A) to 1 to 30 million, there is a tendency to suppress the occurrence of cracking of the adhesive sheet, while suppressing the increase in viscosity and the occurrence of gelation. The weight average molecular weight (Mw) of the polymer in the present specification is a value obtained based on the measurement by GPC (gel permeation chromatography) (polystyrene conversion).

[0083] The content rate of the polymer (A) in the adhesive composition (I) is, for example, 50% by weight or more, can be 60% by weight or more, 70% by weight or more, 75% by weight or more, and further can be 80% by weight or more, based on the solid content. The upper limit of the content rate is, for example, 99% by weight or less, can be 97% by weight or less, and further can be 95% by weight or less.

[0084] <Antistatic agent>

[0085] The adhesive composition (I) contains an antistatic agent. The adhesive composition (I) can contain one or two or more antistatic agents. Examples of the antistatic agent are salt ionic compounds. The ionic compound can be an ionic liquid which is a liquid at ordinary temperature (25°C).

[0086] Examples of the ionic compound are inorganic cation salts and organic cation salts. Examples of the inorganic cation salt are inorganic cation-anion salts. Examples of the cation contained in the inorganic cation salt are alkali metal ions. The alkali metal ion is, for example, a lithium ion, a sodium ion, a potassium ion, and preferably a lithium ion. The inorganic cation salt can be a lithium salt.

[0087] Examples of the anion contained in the inorganic cation salt are Cl - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , (CN)2N - , C4F9SO3 - , C3F7COO - , (CF3SO2)(CF3CO)N - , - O3S(CF2)3SO3 - , and anions represented by the following general formulae (a) to (d).

[0088] (a) (C n F 2n＋1 SO2)2N -(n is an integer from 1 to 10)

[0089] (b) CF2(C m F 2m SO2)2N - (m is an integer from 1 to 10)

[0090] (c) - O3S(CF2) l SO3 - (l is an integer from 1 to 10)

[0091] (d) (C p F 2p＋1 SO2)N - (C q F 2q＋1 SO2) (p and q are independent integers from 1 to 10)

[0092] The anion contained in the inorganic cation salt is preferably a fluorinated anion, more preferably a fluorinated imide anion. Examples of fluorinated imide anions are imide anions having a perfluoroalkyl group. More specific examples of fluorinated imide anions are (CF3SO2)(CF3CO)N. - The anion represented by the above general formula (a), (b) or (d) is preferably (CF3SO2)2N. - (C2F5SO2)2N - The (perfluoroalkyl sulfonyl)imide represented by general formula (a) is more preferably (CF3SO2)2N. - The term refers to bis(trifluoromethanesulfonyl)imide. A preferred example of an inorganic cation salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0093] Examples of organic cationic salts are organic cationic-anionic salts. Examples of cations contained in organic cationic salts are organic compounds containing organic groups. .organic Contained in Examples are nitrogen-containing Sulfur-containing Phosphorus Nitrogen-containing Sulfur-containing Nitrogen-containing Examples include ammonium cations and piperidine. cationic, pyrrolidine Cations, Pyridine Cations, cations with a pyrrolidine skeleton, cations with a pyrrole skeleton, imidazole Cations, Tetrahydropyrimidine Cations, dihydropyrimidines cationic, pyrazole Cationic, pyrazoline Cationic. Sulfur-containing Examples are sulfonium cations. Phosphorus-containing Examples are Cationic. Organic Examples of the organic group contained in the organic cation are alkyl groups, alkoxy groups, alkenyl groups. Preferred organic cations are alkylpyridinium cations. Specific examples of the organic cation are tetraalkylammonium cations (e.g., tributylmethylammonium cation), alkylpiperidinium cations, alkylpyrrolidinium cations. Cationic. Organic Cationic. Organic

[0094] Examples of the anion contained in the organic cationic salt are the same as those of the anion contained in the inorganic cationic salt. Examples of the preferred organic cationic salt are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide salt (EMI-FSI), trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

[0095] The inorganic cationic salt and the organic cationic salt can also be used in combination in the antistatic agent. The antistatic agent preferably contains the organic cationic salt. By causing the antistatic agent to contain the organic cationic salt, it is possible to suppress the increase in the electrical conductivity after the humidification test. Thereby, it is possible to suppress the decrease in the sensitivity of the touch sensor possessed by the image display device.

[0096] The blending amount of the antistatic agent in the adhesive composition (I) is, for example, 0.5 parts by weight or more, can be 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, and further can be 4 parts by weight or more, with respect to 100 parts by weight of the polymer (A). The upper limit of the blending amount can be, 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, and further can be 6 parts by weight or less, with respect to 100 parts by weight of the polymer (A). By appropriately adjusting the blending amount of the antistatic agent in the adhesive composition (I), it is possible to further improve the durability of the adhesive sheet 1. Furthermore, by appropriately adjusting the content of the antistatic agent, it is possible to suppress the increase in the electrical conductivity after the humidification test. Thereby, it is possible to suppress the decrease in the sensitivity of the touch sensor possessed by the image display device. Furthermore, by appropriately adjusting the content of the antistatic agent, the surface resistivity on the adhesive sheet 1 side of the optical stack 10A is more unlikely to increase even in a low-temperature environment, that is, the ratio R / R1 can be reduced.

[0097] <Free radical scavenger>

[0098] The adhesive composition (I) can further contain a free radical scavenger. Examples of the free radical scavenger are various antioxidants such as hindered phenol-based, hindered amine-based, phosphite-based, phenol and sulfide-based, and blended systems obtained by mixing these systems.

[0099] The antioxidant is, for example, a radical chain terminator and a peroxide decomposer.

[0100] The antioxidant can be at least one selected from the group consisting of hindered phenols, hindered amines, and phosphites.

[0101] The hindered phenol antioxidant can have a structure in which a tert-butyl group is bonded to at least one carbon atom adjacent to a carbon atom on which an OH group is bonded on an aromatic ring of the phenol. Examples of the hindered phenol antioxidant are dibutylhydroxytoluene (BHT), and Irganox 1010, Irganox 1010FF, Irganox 1035, Irganox 1035FF, Irganox 1076, Irganox 1076FD, Irganox 1076DWJ, Irganox 1098, Irganox 1135, Irganox 1330, Irganox 1726, Irganox 1425WL, Irganox 1520L, Irganox 245, Irganox 245FF, Irganox 259, Irganox 3114, Irganox 565, and Irganox 295 (all are trade names, manufactured by BASF Corporation).

[0102] The hindered amine antioxidant can have at least one hindered piperidine group in one molecule. Examples of the hindered amine antioxidant are ADK STAB LA-63, ADK STAB LA-63P, ADK STAB LA-52, and ADK STAB LA-57 (all are trade names, manufactured by ADEKA Corporation).

[0103] Examples of the phosphite antioxidant are triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite, and ADK STAB 2112, ADK STAB 2112RG, ADK STAB 1178, and ADK STAB 3010 (all are trade names, manufactured by ADEKA Corporation).

[0104] Examples of the phenolic antioxidant are monophenolic antioxidants, diphenolic antioxidants, and high molecular phenolic antioxidants. Examples of the monophenolic antioxidant are 2,6-di-tert-butyl-p-cresol, butylated hydroxyl anisole, 2,6-di-tert-butyl-4-ethylphenol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid stearyl ester. Examples of the diphenolic antioxidant are 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane. Examples of the high molecular phenolic antioxidant are 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis(4'-hydroxy-3'-tert-butylphenyl)butanoic acid]glycol ester, 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

[0105] Examples of the sulfide antioxidant are ADK STAB AO-503 and ADK STAB AO-26 (both are trade names, manufactured by ADEKA Corporation).

[0106] The molecular weight of the radical scavenger (e.g., antioxidant) can 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 the molecular weight is, for example, 100 or more. According to the research by the present inventors and the like, the radical scavenger having the molecular weight in the above range is particularly suitable for inhibiting the amount of radical generation in the adhesive sheet formed from the adhesive composition (I).

[0107] The radical scavenger (e.g., antioxidant) can be a liquid at ordinary temperature (25°C).

[0108] The blending amount of the radical scavenger in the adhesive composition (I) is, for example, 0.1 parts by weight or more, and can be 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, and further can be 0.5 parts by weight or more, with respect to 100 parts by weight of the polymer (A). The upper limit of the blending amount is, for example, 15 parts by weight or less, and can be 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 parts by weight or less, and further can be 2 parts by weight or less, with respect to 100 parts by weight of the polymer (A).

[0109] <Additives>

[0110] The adhesive composition (I) can further contain a material other than the polymer (A), the antistatic agent, and the radical scavenger. Examples of the material are additives. Examples of the additives are crosslinking agents, silane coupling agents, coloring agents such as pigments and dyes, ultraviolet absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, reworkability improvers, softening agents, polymerization inhibitors, rust preventives, inorganic fillers, organic fillers, powders such as metal powders, particles, and foils. The additives can be blended in a range 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, in total, with respect to 100 parts by weight of the polymer (A).

[0111] Examples of the crosslinking agent are organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent are isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. The organic crosslinking agent and the polyfunctional metal chelate can be used for any type of the adhesive composition (I) of the solvent type and the active energy ray-curable type. In the case where the adhesive composition (I) is of the solvent type, the crosslinking agent is preferably a peroxide crosslinking agent or an isocyanate crosslinking agent. The peroxide crosslinking agent can be used in combination with the isocyanate crosslinking agent. The adhesive composition (I) can contain the isocyanate crosslinking agent, can contain the peroxide crosslinking agent, and can contain both the isocyanate crosslinking agent and the peroxide crosslinking agent. The adhesive composition (I) preferably contains the peroxide crosslinking agent and the radical scavenger.

[0112] Examples of the isocyanate-based crosslinking agent are aromatic isocyanate compounds such as toluene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and polymethylene polyphenyl isocyanate; alicyclic isocyanate compounds such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and isophorone diisocyanate; and aliphatic isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate. The isocyanate-based crosslinking agent can be a compound (adduct) obtained by adding a polyol compound such as trimethylolpropane to the above isocyanate compound; a compound obtained by adding a polyol such as a polyether polyol, a polyester polyol, an acrylic polyol, a polybutadiene polyol, and a polyisoprene polyol to the above isocyanate compound; or a derivative of the above isocyanate compound such as isocyanurate. Specific examples of the derivative are trimethylolpropane / toluene diisocyanate trimer adduct (for example, Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (for example, Coronate HL manufactured by Nippon Polyurethane Industry Co., Ltd.), and isocyanurate of hexamethylene diisocyanate (for example, Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd.).

[0113] In the case where the adhesive composition (I) contains the isocyanate-based crosslinking agent, the blending amount thereof is, for example, 0.1 to 10 parts by weight, can be 0.2 to 5 parts by weight, 0.25 to 3 parts by weight, 0.3 to 1 part by weight, and further can be 0.3 to 0.5 parts by weight, relative to 100 parts by weight of the polymer (A).

[0114] Examples of the peroxide-based crosslinking agent are di(2-ethylhexyl)peroxydicarbonate, di(4-tert-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, tert-butylperoxyneodecanate, tert-hexylperoxy-pivalate, tert-butylperoxypivalate, dilaurylperoxide, di-n-octylperoxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, benzoylperoxide, tert-butylperoxyisobutyrate, and 1,1-di(tert-hexylperoxy)cyclohexane. The peroxide-based crosslinking agent can be benzoylperoxide because of excellent crosslinking reaction efficiency.

[0115] In the case where the adhesive composition (I) contains the peroxide-based crosslinking agent, the blending amount thereof is, for example, 0.005 to 5 parts by weight, can be 0.01 to 3 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, and further can be 0.07 to 0.2 parts by weight, relative to 100 parts by weight of the polymer (A).

[0116] Examples of the silane coupling agent are 3-glycidoxypropyltrimethoxysilane, 3- glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4- epoxycyclohexyl)ethyltrimethoxysilane, and the like silane coupling agents containing an epoxy group, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3- aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-gamma-aminopropyltrimethoxysilane, and the like silane coupling agents containing an amino group, 3-acryloyloxypropyltrimethoxysilane, 3- methacryloyloxypropyltriethoxysilane, and the like silane coupling agents containing a (meth)acryloyl group, 3-isocyanatepropyltriethoxysilane, and the like silane coupling agents containing an isocyanate group.

[0117] In the case where the adhesive composition (I) contains a silane coupling agent, the blending amount thereof is, for example, 5 parts by weight or less, can be 3 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, further can be 0.05 parts by weight or less, relative to 100 parts by weight of the polymer (A). The adhesive composition (I) can also be free of a silane coupling agent.

[0118] The type of the adhesive composition (I) is, for example, emulsion type, solvent type (solution type), active energy ray-curable type (photocurable type), hot melt type (hot melt type). From the viewpoint of being able to form an adhesive sheet excellent in durability, the adhesive composition (I) can be of the solvent type or the active energy ray-curable type, and can also be of the solvent type. The adhesive composition (I) of the solvent type can be free of a photocuring agent such as an ultraviolet curing agent.

[0119] The adhesive composition (I) can be used, for example, for an optical laminate. In other words, the adhesive composition (I) can be an adhesive composition for an optical laminate. Note that the use of the adhesive composition (I) is not limited to the above-described examples.

[0120] In this embodiment, when the polymer (A) is composed of the aforementioned monomers, the glass transition temperature (Tg) of the polymer (A), calculated according to the FOX formula, can be less than -55°C. The glass transition temperature (Tg) of the polymer (A) tends to be related to the glass transition temperature of the adhesive sheet 1. By making the glass transition temperature (Tg) of the polymer (A) less than, for example, 55°C, the free volume of the polymer (A) contained in the adhesive sheet 1 is less likely to decrease even in low-temperature environments. If the free volume of the polymer (A) is less likely to decrease, spaces that allow the antistatic agent to move are easily created in the adhesive sheet 1. Therefore, the antistatic agent can easily move within the adhesive sheet 1, suppressing the increase in surface resistivity, and thus, there is a tendency to suppress the decrease in sensitivity of the touch sensor provided with the image display device. Furthermore, by making the glass transition temperature (Tg) of the polymer (A) less than, for example, 55°C, the movement of the side chains of the polymer (A) in the optical laminate 10A is less likely to decrease even in, for example, low-temperature environments. Therefore, even in low-temperature environments, the decrease in ionic conductivity can be further suppressed. As a result, even in low-temperature environments, the increase in surface resistivity on the adhesive sheet 1 side of the optical laminate 10A can be further suppressed. That is, the ratio R / R1 can be reduced.

[0121] The glass transition temperature (Tg) can be below -60°C or below -65°C. For example, the lower limit of the glass transition temperature (Tg) is -70°C. It should be noted that the FOX formula can be expressed as follows.

[0122] 1 / Tg=w1 / Tg1+w2 / Tg2+···+w m / Tg m

[0123] In the above formula, Tg is the glass transition temperature [K] of polymer (A). w1, w2, ... w m These represent the weight fractions of each monomer in the monomer group. Tg1, Tg2, ..., Tg m Let w1 be the glass transition temperature [K] of the homopolymer of each monomer. m is a positive integer. As an example, w1 is the weight fraction of the first monomer in the monomer group, and Tg1 is the glass transition temperature [K] of the homopolymer of the first monomer. By calculating the glass transition temperature [K] of polymer (A] from the above formula and performing unit conversion, the glass transition temperature Tg [°C] of polymer (A) can be calculated.

[0124] The relative dielectric constant P of the adhesive sheet 1 at a frequency of 100 Hz is, for example, 1000 or more. By making the relative dielectric constant P 1000 or more, even if an optical film, particularly a polarizing film, having a low relative dielectric constant is used in combination with the adhesive sheet 1, the tendency of the sensitivity of the touch sensor provided in the image display device to decrease can be suppressed. Further, by making the relative dielectric constant P of the adhesive sheet 1 1000 or more, the conductivity of the adhesive sheet 1 can be further improved. Thus, the optical laminate 10A can further suppress the increase in the surface resistivity of the adhesive sheet 1 side of the optical laminate 10A, for example, in a low-temperature environment. That is, the ratio R / R1 can be further reduced.

[0125] The relative dielectric constant P can be measured by the following method. First, as a test sheet, an adhesive sheet 1 having a thickness adjusted to 30 μm is produced. For this test sheet, the relative dielectric constant at a frequency of 100 Hz is measured by an automatic balance bridge method (variometer bridge method) based on JIS K6911:1995. The obtained measured value can be regarded as the relative dielectric constant P. Details of the measurement conditions of the relative dielectric constant are as follows.

[0126] • Measurement conditions

[0127] Measurement method: capacity method (device: 4294A Precision Impedance Analyzer manufactured by Agilent Technologies)

[0128] Electrode configuration: aluminum plate having a diameter of 12.1 mm and a thickness of 0.5 mm

[0129] Counter electrode: 3 oz copper plate

[0130] Measurement environment: 23 ± 1°C, 52 ± 1% RH

[0131] The relative dielectric constant P can be preferably 1300 or more, 1800 or more, 2000 or more, and further 2500 or more. The upper limit of the relative dielectric constant P is, for example, 5000 or less.

[0132] As described above, in the adhesive sheet 1, for example, the glass transition temperature Tg of the polymer (A) is less than -55°C, and the relative dielectric constant P of the adhesive sheet 1 at a frequency of 100 Hz is 1000 or more. Thus, the motion of the side chain of the polymer (A) is less likely to decrease, and the conductivity of the adhesive sheet 1 can be further improved. As a result, the increase in the surface resistivity of the adhesive sheet 1 side of the optical laminate 10A at 25°C and the increase in the surface resistivity of the adhesive sheet 1 side of the optical laminate 10A at -15°C can be further suppressed. As a result, the ratio R / R1 can be reduced.

[0133] [Optical film]

[0134] The optical film 2 contains at least one selected from a polarizing film and a phase difference film, for example. The optical film 2 can be a laminated film containing a polarizing film and / or a phase difference film. The optical film 2 can contain a film made of glass.

[0135] The polarizing film contains a polarizer. Typically, the polarizing film contains a polarizer and a protective film (transparent protective film). The protective film is disposed in contact with a main surface of the polarizer, for example. The polarizer can be disposed between two protective films. The protective film can be disposed on at least one surface of the polarizer.

[0136] As the polarizer, there is no particular limitation, and examples that can be given include: a polarizer obtained by adsorbing a dichroic substance such as iodine or a dichroic dye to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene-vinyl acetate copolymer-based partially saponified film, and the like, and performing unidirectional stretching; a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol, a dehydrochlorinated product of polyvinyl chloride, and the like. The polarizer is typically formed 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.

[0137] The thickness of the polarizer is not particularly limited, and is, for example, 80 μm or less, can be 50 μm or less, 30 μm or less, 25 μm or less, and further can be 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, can be 5 μm or more, 10 μm or more, and further can be 15 μm or more. A thin polarizer (for example, 20 μm or less in thickness) can suppress dimensional changes, and is useful in improving the durability of the optical laminate, particularly the durability at high temperatures.

[0138] As the material of the protective film, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. As specific examples of such a thermoplastic resin, cellulose resins such as cellulose triacetate, polyester resins, polyether sulfone 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 listed. The material of the protective film can be a thermosetting resin such as a (meth)acrylic resin, a urethane resin, an acryl urethane resin, an epoxy resin, a silicone resin, or an ultraviolet-curable resin. In the case where the polarizing film has two protective films, the materials of the two protective films can be the same as or different from each other. For example, a protective film formed of a thermoplastic resin can be attached to one main surface of the polarizer via an adhesive, and a protective film formed of a thermosetting resin or an ultraviolet-curable resin can be attached to the other main surface of the polarizer. The protective film can contain one or more arbitrary additives. As the additives, for example, ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, coloration-preventing agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like can be listed.

[0139] The thickness of the protective film can be appropriately determined, and is generally about 10 to 200 μm in consideration of strength, handleability, film thickness, and the like.

[0140] The polarizer and the protective film are generally bonded together via an aqueous adhesive or the like. As the aqueous adhesive, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latexes, aqueous polyurethanes, aqueous polyesters, and the like can be exemplified. As other adhesives other than the above-described adhesives, ultraviolet-curable adhesives, electron beam-curable adhesives, and the like can be listed. Electron beam-curable polarizing plate adhesives exhibit suitable adhesiveness to various protective films. The adhesive can also contain a metal compound filler.

[0141] In the polarizing film, a phase difference film or the like can also be formed on the polarizer instead of the protective film. Another protective film, a phase difference film, or the like can also be further provided on the protective film.

[0142] To the protective film, a hard coat layer can be provided on a surface opposite to the surface bonded to the polarizer, and a treatment for the purpose of antireflection, antiblocking, diffusion, antiglare, or the like can also be performed.

[0143] The polarizing film can be a circularly polarizing film.

[0144] As the phase difference film, a phase difference film obtained by stretching a high molecular film, a phase difference film obtained by orienting and immobilizing a liquid crystal material can be used. The phase difference film has, for example, birefringence in-plane and / or in the thickness direction.

[0145] As the phase difference film, there can be mentioned a phase difference film for antireflection (see Japanese Patent Application Laid-Open No. 2012-133303

[0221] ,

[0222] ,

[0228] ), a phase difference film for viewing angle compensation (see Japanese Patent Application Laid-Open No. 2012-133303

[0225] ,

[0226] ), a tilt orientation phase difference film for viewing angle compensation (see Japanese Patent Application Laid-Open No. 2012-133303

[0227] ), and the like.

[0146] As the phase difference film, it is only required to substantially have the above-mentioned function, and there is no particular limitation on, for example, a phase difference value, a disposition angle, a three-dimensional birefringence, whether it is a single layer or a multilayer, and the like, and a publicly known phase difference film can be used.

[0147] The thickness of the phase difference film is preferably 20 μm or less, more preferably 10 μm or less, further preferably 1 to 9 μm, particularly preferably 3 to 8 μm.

[0148] The phase difference film can be composed of, for example, two layers of a 1 / 4 wave plate or a 1 / 2 wave plate obtained by orienting and immobilizing a liquid crystal material.

[0149] [Method for manufacturing adhesive sheet]

[0150] The adhesive sheet 1 is formed from the adhesive composition (I). The adhesive sheet 1 contains, for example, a crosslinked product of a (meth)acrylic polymer. The adhesive sheet 1 is formed from the adhesive composition (I) by the following method.

[0151] The method for manufacturing the adhesive sheet 1 includes, for example: applying the adhesive composition (I) to a substrate to form an applied film; and drying the obtained applied film. By drying the applied film, the adhesive sheet 1 is formed on the substrate. Thus, a laminate L1 composed of the substrate and the adhesive sheet 1 is obtained.

[0152] As the substrate, a release film can be used, for example. The adhesive sheet 1 formed on the release film can be transferred to, for example, the optical film 2 or the like. The substrate can be an optical film.

[0153] The release film can be used as a separator until the adhesive sheet 1 is supplied to actual use after the adhesive sheet 1 is transferred to the optical film 2, and thus simplification of the process can be achieved.

[0154] As the material for the release film, a suitable sheet material such as a plastic film, paper, cloth, a porous material such as nonwoven fabric, a net, a foamed sheet, a metal foil, and a laminate thereof, and the like can be used, and from the viewpoint of surface smoothness, a plastic film is preferably used.

[0155] As the plastic film, there are no particular limitations, and examples thereof include polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like.

[0156] The thickness of the release film is usually 5 to 200 μm, and preferably about 5 to 100 μm. The release film is subjected to a release treatment with, for example, silicone-based, fluorine-based, long-chain alkyl-based, or the like. The release film can be subjected to a release and stain-proof treatment with a release agent using a fatty acid amide, silica powder, or the like, an antistatic treatment of a coating type, a mixed-in type, a vapor deposition type, or the like.

[0157] A solution (adhesive solution) containing the adhesive composition (I) can be applied to the substrate. The solid content concentration of the adhesive solution is, for example, 5 to 50% by weight, and preferably 10 to 40% by weight. Note that the adhesive solution can be prepared by adding, to the adhesive composition (I), a solvent identical to the polymerization solvent or a different solvent, as appropriate, in correspondence with the polymerization mode of the (meth)acrylic polymer (A).

[0158] As the method of applying the adhesive composition (I) to the substrate, various methods can be employed, and examples thereof include roll coating, roll kiss coating, gravure coating, reverse coating, roll brushing, spraying, dip roll coating, bar coating, blade coating, air-knife coating, curtain coating, lip coating, extrusion coating using a die coater, and the like. The application amount of the adhesive composition (I) can be adjusted as appropriate in accordance with the thickness of the target adhesive sheet 1.

[0159] The coated film is cured by drying, thereby forming the adhesive sheet 1. The drying temperature of the coated film is, for example, 130°C or lower, preferably 125°C or lower, more preferably 120°C or lower, further preferably 110°C or lower, and particularly preferably 100°C or lower. The drying temperature of the coated film can be 60°C or higher, or 80°C or higher. In the case where the drying temperature is 60°C or higher, there is a tendency that, for example, the reaction of the isocyanate-based crosslinking agent proceeds smoothly, thereby enabling the cohesiveness of the adhesive sheet 1 to be improved and the display unevenness of the image display device to be reduced. In the case where the drying temperature is 130°C or lower, there is a tendency that, for example, the reaction rate of the isocyanate-based crosslinking agent can be adjusted appropriately and the transparency can be ensured.

[0160] The drying time of the coated film can be adjusted as appropriate in accordance with the composition of the adhesive composition (I), and is preferably 30 seconds to 300 seconds, further preferably 40 seconds to 240 seconds, and particularly preferably 60 seconds to 180 seconds.

[0161] The thickness of the adhesive sheet 1 can be 2 to 150 μm, 2 to 100 μm, or 5 to 50 μm. By appropriately adjusting the thickness of the adhesive sheet 1, the adhesion of the adhesive sheet 1 to the optical film 2 can be improved. Further, by appropriately adjusting the thickness of the adhesive sheet 1, peeling of the adhesive sheet 1 from a glass or an image display device or the like to which the adhesive sheet 1 is adhered can be suppressed.

[0162] Figure 2 is a cross-sectional view schematically showing another example of the optical laminate of the present embodiment. As shown in Figure 2 the optical laminate 10B has a layered structure in which the release liner 3, the adhesive sheet 1, and the optical film 2 are sequentially layered. The optical laminate 10B can be used after the release liner 3 is peeled off, for example, to be attached to an image display unit. The examples below can be combined with each other as long as they are not technically contradictory.

[0163] As a material constituting the release liner 3, for example, a plastic film such as a polyethylene film, a polypropylene film, a polyethylene terephthalate film, a polyester film, paper, cloth, a nonwoven fabric, a mesh, a foamed sheet, a metal foil, a laminate thereof, or the like can be given. From the viewpoint of surface smoothness, a plastic film is preferably used.

[0164] As the plastic film, there is no particular limitation as long as it is a film capable of protecting the adhesive sheet 1, and for example, a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, or the like can be given.

[0165] The thickness of the release liner 3 is usually 5 to 200 μm, and is preferably about 5 to 100 μm. If necessary, the release liner 3 can be subjected to a mold release and stain-proof treatment using a mold release agent of a silicone type, a fluorine type, a long-chain alkyl type, or a fatty acid amide type, a silica powder, or the like, an antistatic treatment of a coating type, a mixed type, a vapor deposition type, or the like. In particular, by appropriately performing a release treatment such as a silicone treatment, a long-chain alkyl treatment, a fluorine treatment, or the like on the surface of the release liner 3, the releasability from the adhesive sheet 1 can be further improved.

[0166] Note that, as described above, a mold release film used when the adhesive sheet 1 is produced can also be used as the release liner 3.

[0167] The optical laminate of the present embodiment can be circulated and stored, for example, in the form of a roll-up in which a band-shaped optical laminate is wound, or in the form of a single sheet-shaped optical laminate. The optical laminate of the present embodiment is suitable for use in an image display device used in an environment in which static electricity is particularly likely to be generated, particularly a display for a vehicle. As the display for a vehicle, for example, a meter panel for a car navigation device, a cluster panel, a mirror display, and the like can be given. The cluster panel is a panel that displays the running speed of a vehicle, the rotation speed of an engine, and the like.

[0168] [Embodiment of image display panel]

[0169] Figure 3 is a cross-sectional view schematically showing an example of an image display panel of the present embodiment. As shown in Figure 3 the image display panel 11A has the optical laminate 10A, and further has, for example, an image display unit 30A. In detail, the optical laminate 10A is attached to the image display unit 30A via the adhesive sheet 1.

[0170] The image display unit 30A has, for example, an image forming layer 32, a first transparent substrate 31, and a second transparent substrate 33. The image forming layer 32 is disposed 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 in contact with the first transparent substrate 31 of the image display unit 30A, for example.

[0171] The image forming layer 32 is, for example, a liquid crystal layer containing liquid crystal molecules that have undergone uniform orientation in the absence of an electric field. The liquid crystal layer containing such liquid crystal molecules is suitable for an IPS (In-Plane-Switching) mode. However, the liquid crystal layer can also be used for a TN (Twisted Nematic) mode, an STN (Super Twisted Nematic) mode, a pi (π) mode, a VA (Vertical Alignment) mode, and the like. In the present specification, an image display unit having a liquid crystal layer is sometimes referred to as a liquid crystal unit, and an image display panel having a liquid crystal unit is sometimes referred to as a liquid crystal panel. Note that the image forming layer 32 can also be an EL light-emitting layer.

[0172] The thickness of the image forming layer 32 is, for example, 1.5 μm to 4 μm.

[0173] As the material of the first transparent substrate 31 and the second transparent substrate 33, for example, glass and a polymer can be given. In the present specification, a transparent substrate composed of a polymer is sometimes referred to as a polymer film. As the polymer constituting the transparent substrate, for example, polyethylene terephthalate, polycycloolefin, polycarbonate, and the like can be given. The thickness of the transparent substrate composed of glass is, for example, 0.1 mm to 1 mm. The thickness of the transparent substrate composed of a polymer is, for example, 10 μm to 200 μm.

[0174] The image display unit 30A can further include other layers than the image forming layer 32, the first transparent substrate 31, and the second transparent substrate 33. As the other layers, for example, a color filter, an easy-adhesion layer, and a hard coat layer can be given. The color filter is, for example, disposed closer to the visible side than the image forming layer 32, and is preferably positioned 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, for example, disposed on the surface of the first transparent substrate 31 or the second transparent substrate 33.

[0175] The image display panel 11A can also further include other members than the optical laminate 10A and the image display unit 30A. For example, the image display panel 11A can further include a conduction structure (not shown) electrically connected to the side surface of the optical laminate 10A. If the conduction structure is grounded, it is easy to suppress the charging of the optical laminate 10A due to static electricity. The conduction structure can cover the entire side surface of the optical laminate 10A, or can partially cover the side surface of the optical laminate 10A. The ratio of the area of the side surface of the optical laminate 10A covered by the conduction structure to the area of the entire side surface of the optical laminate 10A is, for example, 1% or more, and is preferably 3% or more.

[0176] As the material of the conduction structure, for example, a conductive paste composed of a metal such as silver, gold, and the like; a conductive adhesive; and other conductive materials can be given. The conduction structure can be a wiring extending from the side surface of the optical laminate 10A.

[0177] The image display panel 11A can also further include other optical films than the optical film 2. As the other optical films, for example, a polarizing plate, a reflection plate, a reflection-transmission plate, a viewing angle compensation film, a brightness improvement film, and the like that can be used for an image display device can be given. The image display panel 11A can include one or two or more other optical films among these.

[0178] In the case where the other optical film is a polarizing plate, the polarizing plate can be attached to the second transparent substrate 33 of the image display unit 30A, for example, via the adhesive sheet 1. The polarizing plate has, for example, the configuration described above for the optical film 2. In the polarizing plate as the other 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 attaching the polarizing plate to the second transparent substrate 33, the materials described above for the adhesive sheet 1 can be used. The thickness of the 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 further preferably 5 to 35 μm.

[0179] Figure 4 is a cross-sectional view schematically showing another example of the image display panel of the present embodiment. As shown in Figure 4 the image display panel 11B further includes a conductive layer 40 disposed between the optical laminate 10A and the image display unit 30A. The image display panel is preferably the image display panel 11A that does not include the conductive layer 40. In the image display panel 11B provided with the conductive layer 40, there is a tendency that the reflectance becomes high, which sometimes causes a decrease in the visual recognition of the display. In the image display panel 11A that does not include the conductive layer 40, it is preferable to provide a conductive portion (the conductive structure described above) adjacent to the adhesive sheet 1. As the conductive portion, for example, a conductive silver paste can be used. After the optical laminate 10A is attached to the image display unit 30A, the conductive silver paste or the like is applied to the side surface portion of the adhesive sheet 1 to provide the conductive portion, which is connected to other wiring, a frame of the image display device, or the like from there, whereby the antistatic property of the image display panel can be improved.

[0180] The conductive layer 40 is, for example, a layer including a conductive agent. As the conductive agent, a metal oxide, a conductive polymer, and the conductive agent described above for the adhesive sheet 1, or the like can be used. The thickness of the conductive layer 40 is, for example, 5 nm to 180 nm. The surface resistivity of the conductive layer 40 is, for example, 1.0 x 10 6 Ω / D to 1.0 x 10 10 Ω / D, preferably 1.0 x 10 8 Ω / D to 1.0 x 10 9 Ω / D.

[0181] The image display panel of the present embodiment can also be an image display panel having a built-in touch sensor function. An example of the image display panel having a built-in touch sensor function is shown in Figure 5 . Figure 5 is a cross-sectional view schematically showing another example of the image display panel of the present embodiment. As shown in Figure 5As shown, the image display panel 11C has the image display unit 30B further including the touch sensor electrode section 35. In the image display unit 30B, the touch sensor electrode section 35 is disposed between the first transparent substrate 31 and the second transparent substrate 33. The touch sensor electrode section 35 has a function of a touch sensor and a function of a touch driver. The image display panel 11C is a so-called in-cell type image display panel, and the image display unit 30B is a so-called in-cell type image display unit. Note, however, that in the image display unit 30B, the touch sensor electrode section 35 can be disposed closer to the visible side than the first transparent substrate 31. That is, the image display panel 11C can be a so-called on-cell type image display panel, and the image display unit 30B can be a so-called on-cell type image display unit.

[0182] The touch sensor electrode section 35 has, for example, a touch sensor electrode 36 and a touch driver electrode 37. The touch sensor electrode 36 refers to a (receiving) electrode for touch detection. The touch sensor electrode 36 and the touch driver electrode 37 can be formed independently of each other by various patterns. For example, in a case where the image display unit 30B is flat, the touch sensor electrode 36 and the touch driver electrode 37 can be independently provided in the X-axis direction and the Y-axis direction, respectively, to be formed in a pattern in which they cross at right angles. In a case where the image display unit 30B is curved, the touch sensor electrode 36 and the touch driver electrode 37 can be independently provided in the X-axis direction and the Y-axis direction, respectively, to be formed in a pattern in which they cross at right angles. Figure 5 In the touch sensor electrode section 35, the touch sensor electrode 36 can be disposed closer to the visible side than the touch driver electrode 37. However, the touch driver electrode 37 can be disposed closer to the visible side than the touch sensor electrode 36. In the touch sensor electrode section 35, the touch sensor electrode 36 and the touch driver electrode 37 can be integrated.

[0183] In the touch sensor electrode section 35, the touch sensor electrode 36 and the touch driver electrode 37 can be disposed so as to be in contact with each other. For example, the touch sensor electrode 36 and the touch driver electrode 37 can be disposed so as to be in contact with each other in the image display unit 30B. Figure 5 In the touch sensor electrode section 35, the touch sensor electrode 36 and the touch driver electrode 37 can be disposed so as to be in contact with each other. For example, the touch sensor electrode 36 and the touch driver electrode 37 can be disposed so as to be in contact with each other in the image display unit 30B.

[0184] In the touch sensor electrode section 35, the touch sensor electrode 36 and the touch driver electrode 37 can not be in contact with each other. For example, the touch sensor electrode 36 can be disposed between the image forming layer 32 and the first transparent substrate 31, and the touch driver electrode 37 can be disposed between the image forming layer 32 and the second transparent substrate 33.

[0185] The driving electrode (the touch driver electrode 37, or an electrode integrated with the touch sensor electrode 36 and the touch driver electrode 37) in the touch sensor electrode section 35 can function as a common electrode for controlling the image forming layer 32.

[0186] The touch sensor electrode 36 (electrostatic capacity sensor), the touch drive electrode 37, or an electrode formed by integrating them, which constitute the touch sensing electrode section 35, function as a transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and for example, a metal such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, tungsten, and an alloy thereof, or the like can be given. The material of the transparent conductive layer can also be an oxide of a metal such as indium, tin, zinc, gallium, antimony, zirconium, and cadmium. As the oxide, for example, indium oxide, tin oxide, titanium oxide, cadmium oxide, and a mixture thereof, or the like can be given. The material of the transparent conductive layer can also be a metal compound such as copper iodide. The material of the transparent conductive layer is preferably indium tin oxide (ITO) containing tin oxide, tin oxide containing antimony, or the like, and particularly preferably ITO. In the case where 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.

[0187] The electrode (the touch sensor electrode 36, the touch drive electrode 37, or an electrode formed by integrating them) constituting the touch sensing electrode section 35 can be formed in a transparent electrode pattern between the first transparent substrate 31 and the second transparent substrate 33 by a conventional method. The transparent electrode pattern is electrically connected to, for example, a lead formed on the end portion of the transparent substrate. The lead is connected to, for example, a controller IC. As the shape of the transparent electrode pattern, any shape corresponding to the use, such as a comb shape, a stripe shape, a diamond shape, or the like, can be adopted. 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.

[0188] [Embodiment of image display device]

[0189] The image display device of the present embodiment has, for example, an image display panel 11A and an illumination system. Note that, instead of the image display panel 11A, an image display panel 11B or 11C of Figure 4 and 5 may be used. In the image display device, the image display panel 11A is disposed, for example, closer to the visible side than the illumination system. The illumination system has, for example, a backlight or a reflection plate, and irradiates light to the image display panel 11A.

[0190] The image display device can be an organic EL display or a liquid crystal display. However, the image display device is not limited to this example, and can 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 a household appliance, a vehicle, a public information display (PID), or the like, and is preferably a display for a vehicle.

[0191] Examples

[0192] Hereinafter, the present application will be described in more detail by way of examples. The present application is not limited to the following examples.

[0193] <Weight average molecular weight of (meth)acrylic polymer>

[0194] 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.

[0195] • Analysis device: HLC-8120 GPC manufactured by Tosoh Corporation

[0196] • Chromatography column: G7000H manufactured by Tosoh Corporation XL + GMH XL + GMH XL

[0197] • Column size: 7.8 mmφ x 30 cm each, total 90 cm

[0198] • Column temperature: 40°C

[0199] • Flow rate: 0.8 mL / min

[0200] • Injection amount: 100 μL

[0201] • Eluent: Tetrahydrofuran

[0202] • Detector: Differential refractometer (RI)

[0203] • Standard sample: Polystyrene

[0204] [Preparation of (meth)acrylic polymer A1]

[0205] A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introducing tube, and a condenser was charged with a monomer mixture containing ethoxy ethoxy ethyl acrylate (CBA) 20 parts by weight, n-butyl acrylate (BA) 79 parts by weight, and 4-hydroxybutyl acrylate (HBA) 1 part by weight. Further, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) as a polymerization initiator was added together with 100 parts by weight of ethyl acetate with respect to 100 parts by weight of the monomer mixture. While the mixture was slowly stirred, nitrogen gas was introduced into the flask to perform nitrogen gas replacement. The liquid temperature in the flask was maintained at around 55°C and a polymerization reaction was performed for 8 hours, whereby a solution of a (meth)acrylic polymer Al having a weight average molecular weight (Mw) of 1.9 million was prepared. The glass transition temperature of the (meth)acrylic polymer Al calculated according to the FOX equation was -57.0°C.

[0206] [Preparation of (Meth)acrylic Polymer A2]

[0207] A monomer mixture charged into the flask was CBA 51 parts by weight, BA 48 parts by weight, and HBA 1 part by weight, and a solution of a (meth)acrylic polymer A2 having a weight average molecular weight (Mw) of 1.3 million was prepared in the same manner as in the preparation of the (meth)acrylic polymer Al, except for this. The glass transition temperature of the (meth)acrylic polymer A2 calculated according to the FOX equation was -61.1°C.

[0208] [Preparation of (Meth)acrylic Polymer A3]

[0209] A monomer mixture charged into the flask was CBA 51 parts by weight, 2-ethylhexyl acrylate (2EHA) 48 parts by weight, and HBA 1 part by weight, and a solution of a (meth)acrylic polymer A3 having a weight average molecular weight (Mw) of 1.7 million was prepared in the same manner as in the preparation of the (meth)acrylic polymer Al, except for this. The glass transition temperature of the (meth)acrylic polymer A3 calculated according to the FOX equation was -68.2°C.

[0210] [Preparation of (Meth)acrylic Polymer A4]

[0211] A monomer mixture charged into the flask was CBA 20 parts by weight, BA 39 parts by weight, 2EHA 40 parts by weight, and HBA 1 part by weight, and a solution of a (meth)acrylic polymer A4 having a weight average molecular weight (Mw) of 1.8 million was prepared in the same manner as in the preparation of the (meth)acrylic polymer Al, except for this. The glass transition temperature of the (meth)acrylic polymer A4 calculated according to the FOX equation was -63.4°C.

[0212] Preparation of [(meth)acrylic polymer A5]

[0213] A monomer mixture added to a flask was 2-methoxyethyl acrylate (MEA) 98 parts by weight, BA 1 part by weight, and HBA 1 part by weight, and a solution of (meth)acrylic polymer A5 having a weight average molecular weight (Mw) of 2.1 million was prepared in the same manner as in the preparation of (meth)acrylic polymer Al, except for this. The glass transition temperature of (meth)acrylic polymer A5 calculated according to the FOX equation was -49.9°C.

[0214] Preparation of [(meth)acrylic polymer A6]

[0215] A monomer mixture added to a flask was BA 99 parts by weight and HBA 1 part by weight, and a solution of (meth)acrylic polymer A6 having a weight average molecular weight (Mw) of 1.8 million was prepared in the same manner as in the preparation of (meth)acrylic polymer Al, except for this. The glass transition temperature of (meth)acrylic polymer A6 calculated according to the FOX equation was -55.0°C.

[0216] The monomers used in the synthesis of each (meth)acrylic polymer and the amounts added are summarized in Table 1 below. The notation of "-" in the table indicates that the ingredient is not contained.

[0217]

[0218] (Example 1)

[0219] [TAC film with hard coat layer]

[0220] First, a resin solution (DIC Corporation, trade name: UNIDIC 17-806, solid content concentration: 80%) in which a urethane acrylate was dissolved as a main component in butyl acetate was prepared. With respect to 100 parts by weight of the solid content of the resin solution, 5 parts by weight of a photopolymerization initiator (BASF Corporation, trade name: IRGACURE 907) and 0.1 parts by weight of a leveling agent (DIC Corporation, trade name: GRANDIC PC4100) were added to the resin solution. Next, cyclopentanone and propylene glycol monomethyl ether were added to the resin solution in a weight ratio of 45:55 in such a manner that the solid content concentration in the resin solution was adjusted to 36%. Thus, a hard coat layer-forming material was prepared. The obtained forming material was applied to a transparent protective film (TAC film, trade name "KC4UY", manufactured by Konica Minolta Optica, Inc., having a thickness of 40 μm) including cellulose triacetate, and a coating film was formed. At this time, the thickness of the coating film was adjusted so that the thickness of a hard coat layer obtained by curing the forming material was adjusted to 7 μm. Next, the coating film was dried at 90°C for 1 minute, and further, the coating film was irradiated with ultraviolet rays having a cumulative light quantity of 300 mJ / cm2using a high-pressure mercury lamp. Thus, the coating film was cured, and a TAC film with a hard coat layer (HC) was obtained. 2

[0221] [Polarizing plate]

[0222] First, a polyvinyl alcohol film having a thickness of 80 μm was stretched to a stretch ratio of 3 times while being dyed in an iodine solution having a concentration of 0.3% at a temperature of 30°C for 1 minute between a plurality of rolls having different speed ratios. Next, the obtained stretched film was immersed in an aqueous solution having a concentration of 4% of boric acid and a concentration of 10% of potassium iodide at a temperature of 60°C for 0.5 minutes while being stretched to a total stretch ratio of 6 times. Next, the stretched film was washed by being immersed in an aqueous solution having a concentration of 1.5% of potassium iodide at a temperature of 30°C for 10 seconds. Next, the stretched film was dried at 50°C for 4 minutes, and thus a polarizer having a thickness of 30 μm was obtained. A transparent protective film (thickness: 30 μm) formed of a modified acrylic polymer having a lactone ring structure was bonded to one main surface of the obtained polarizer via a polyvinyl alcohol-based adhesive. The above-described TAC film with a hard coat layer (thickness: 47 μm) was bonded to the other main surface of the polarizer via a polyvinyl alcohol-based adhesive. At this time, the other main surface of the polarizer was bonded to the transparent protective film. The bonding of the polarizer and the transparent protective film was performed using a roll laminator. After the polarizer and the transparent protective film were bonded, the obtained laminate was dried at 70°C for 5 minutes using an oven, and thus a polarizing plate composed of a hard coat layer and a polarizing film was obtained.

[0223] [Adhesive sheet] ​

[0224] Further, 0.1 parts by weight of a peroxide crosslinking agent (manufactured by NOF Corporation, trade name; Nyper BMT40SV), 0.4 parts by weight of an isocyanate crosslinking agent (manufactured by DKS Co., Ltd., trade name; Coronate 2770), 6 parts by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) (manufactured by the First Industrial Co., Ltd., trade name; ELEXCEL AS110) as an antistatic agent, 0.5 parts by weight of an antioxidant (manufactured by BASF Corporation, trade name; Irganox 1010), and 0.2 parts by weight of a silane coupling agent (manufactured by Zeon Corporation, trade name; A100) were further compounded with respect to 100 parts by weight of the solid content of the solution of the (meth)acrylic polymer A1, whereby a solution of the (meth)acrylic adhesive composition of Example 1 was prepared.

[0225] Next, the obtained solution was applied to one side of a separator (MRF38 manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.). The separator was a polyethylene terephthalate film treated with a silicone-based release agent. The obtained coated film was dried at 155°C for 1 minute, whereby a laminate L1 in which an adhesive sheet was formed on the surface of the separator was obtained. The thickness of the adhesive sheet was 20 μm.

[0226] [Optical laminate]

[0227] Next, by transferring the adhesive sheet of the obtained laminate L1 to a polarizing plate, a laminate L2 in which a polarizing plate, an adhesive sheet, and a separator were sequentially layered was produced. The separator was peeled from the laminate L2, whereby the optical laminate of Example 1 was obtained.

[0228] (Example 2)

[0229] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A2 was used, and otherwise, the optical laminate of Example 2 was obtained by the same method as in Example 1.

[0230] (Example 3)

[0231] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A3 was used, and otherwise, the optical laminate of Example 3 was obtained by the same method as in Example 1.

[0232] (Example 4)

[0233] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A3 was used, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (manufactured by Solvay) was used as an antistatic agent, and otherwise, the optical laminate of Example 4 was obtained by the same method as in Example 1.

[0234] (Example 5)

[0235] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A4 was used, and 10 parts by weight of EMI-FSI was used as the antistatic agent, and otherwise, the optical laminate of Example 5 was obtained by the same method as Example 1.

[0236] (Comparative Example 1)

[0237] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A4 was used, and otherwise, the optical laminate of Comparative Example 1 was obtained by the same method as Example 1.

[0238] (Comparative Example 2)

[0239] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A5 was used, and 5 parts by weight of LiTFSI was used as the antistatic agent, and otherwise, the optical laminate of Comparative Example 2 was obtained by the same method as Example 1.

[0240] (Comparative Example 3)

[0241] In the production of the adhesive sheet, a solution of the (meth)acrylic polymer A6 was used, and 11 parts by weight of EMI-FSI was used as the antistatic agent, and otherwise, the optical laminate of Comparative Example 3 was obtained by the same method as Example 1.

[0242] The following evaluations were performed on Examples 1 to 5 and Comparative Examples 1 to 3. The evaluation results are shown in Table 2.

[0243] Measurement of Surface Resistivity on the Adhesive Sheet Side of the Optical Laminate

[0244] The surface resistivity R1 at 25°C on the adhesive sheet side of the optical laminate of each of the examples and comparative examples was measured. The measurement of the surface resistivity R1 at 25°C on the adhesive sheet side of the optical laminate was performed using a resistivity meter (Hiresta MCP-HT800 manufactured by Mitsubishi Chemical Analytech) under the conditions of an applied voltage of 250 V and an applied time of 10 seconds.

[0245] For the measurement of the surface resistivity R of the adhesive sheet side of the optical laminate at -15°C, the measurement was performed as described below. The polarizing plate side (hard coat layer side) of the laminate L2 was disposed on a cooling plate set to -15°C. After about 30 seconds had elapsed, the separator was immediately peeled from the laminate L2 and the surface resistivity of the adhesive sheet side was measured. The measurement of the surface resistivity R of the adhesive sheet side of the optical laminate at -15°C was performed using the above-described resistivity meter under the conditions of an applied voltage of 250 V and an application time of 10 seconds.

[0246] <Method for measuring the saturated moisture content of the adhesive sheet>

[0247] About 50 mg of a sample was collected from the adhesive sheet of the optical laminate of each of the examples and comparative examples. The sample was disposed in a moisture adsorption / desorption measuring device (IGA-Sorp, manufactured by Hiden), and moisture was removed from the sample by leaving it at 100°C for 1 hour. The weight at this time was measured, and this weight was taken as W1 [mg]. Next, the sample was left in an environment of 23°C and 55% RH or an environment of 85°C and 85% RH, and the change in the weight of the sample was observed. The weight of the sample when the weight of the sample no longer changed was measured, and this weight was taken as W2 [mg], and the saturated moisture content was measured by the following equation.

[0248] Saturated moisture content [wt%] = {(W2 - W1) / W1} x 100

[0249] <Evaluation of whitening>

[0250] An evaluation laminate that simulated an image display device was produced by bonding a glass plate that simulated the front surface transparent member to the optical film side of the optical laminate via OCA (manufactured by Nitto Electric Industrial Co., Ltd., LUCIA CS CS9821; adhesive without acrylic monomer, thickness 200 μm). Next, the evaluation laminate was bonded to the visual side of the in-cell type liquid crystal cell via the adhesive sheet thereof, thereby producing an in-cell type liquid crystal cell with a laminate. Next, a polarizing plate was bonded to the side opposite the visual side of the in-cell type liquid crystal cell with a laminate in such a manner that it became a crossed Nicol, thereby producing a liquid crystal display panel. After the liquid crystal display panel was cooled using a cooling plate set to -15°C, it was immediately placed on a backlight device, and the polarizing plate surface of the visual side was rubbed several times using a butyronitrile glove, thereby causing static electricity to be generated. The time until the whitening due to static electricity disappeared was measured, and the evaluation was performed in accordance with the following criteria. Note that an evaluation result that was problematic in actual use was "D".

[0251] (Evaluation criteria)

[0252] A: No whitening occurred.

[0253] B: Whitening occurred several times by rubbing, but disappeared within 1 second.

[0254] C: Whitening occurred several times by rubbing, but disappeared within more than 1 second and less than 5 seconds.

[0255] D: Whitening occurred only once by rubbing, and more than 5 seconds passed until disappearance.

[0256]

[0257] As shown in Table 2, in the examples, the surface resistivity of the adhesive sheet at -15°C was 1.0 x 10 10 Ω / D below. The optical laminate of the examples was more suitable for suppressing display failure, typically whitening caused by charging, in a low-temperature environment.

[0258] <Measurement of electrical conductivity>

[0259] Two glass plates having a size of 10 cm x 7 cm and a thickness of 0.7 mm were laminated. At this time, the lamination was performed in a state in which the upper glass plate was offset by about 1 cm in the length direction of the lower glass plate to form a height difference. On both ends of the height difference portion, a conductive paste was applied so as to become about 5 mm square and dried. The distance between the conductive pastes was about 7 cm. Next, the separator was peeled from the laminate L2, and the optical laminate was attached to the conductive pastes and the upper glass plate via the adhesive sheet, whereby a sample was produced.

[0260] The sample produced as described above was heated in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes. Next, the sample was left to stand until cooled to 25°C to stabilize the bonding of the adhesive sheet to the glass plate, and a sample for electrical conductivity measurement was obtained. Then, in a state in which the anode and the cathode of an industrial multimeter (Fluke Corporation, trade name; FLUKE 87V) were connected to each of the conductive pastes of the sample for electrical conductivity measurement, the electrical conductivity at 25°C was measured. The value of the electrical conductivity at this time was set as the initial electrical conductivity C A .

[0261] Next, the electrical conductivity of the sample for electrical conductivity measurement was measured immediately after the sample for electrical conductivity measurement was left to stand at 85°C and 85% RH for 250 hours. The value of the electrical conductivity at this time was set as the electrical conductivity under high temperature and high humidity C B . The ratio C B / C A was calculated. The ratio C B / C A was evaluated in accordance with the following criteria. Note that the evaluation result that is problematic in actual use was "D".

[0262] (Evaluation Criteria)

[0263] A: C B / C A 1.5 or less

[0264] B: C B / C A more than 1.5 and 2.5 or less

[0265] C: C B / C A more than 2.5 and 3.0 or less

[0266] D: C B / C A more than 3.0

[0267]

[0268] As shown in Table 3, in the examples, the increase in the electrical conductivity under high temperature and high humidity was suppressed compared to the initial electrical conductivity. Thus, the optical laminate of the examples is suitable for suppressing the decrease in the sensitivity of the touch sensor provided in the image display device, not only in a low temperature environment, but also under high temperature and high humidity.

[0269] Industrial Applicability

[0270] The optical laminate of the present application can be suitably used for an image display device used in an environment where static electricity is easily generated, particularly, in an environment where other electronic devices are present around, such as the interior of a vehicle.

Claims

1. An optical laminate comprising an adhesive sheet and an optical film, the adhesive sheet is formed from an adhesive composition comprising a polymer (A) and an antistatic agent, The surface resistivity of the optical laminate on the adhesive sheet side at -15°C is 1.0 x 10 10 Ω / □ or less.

2. The optical laminate according to claim 1, wherein the glass transition temperature of the polymer (A) calculated according to FOX formula is less than -55°C, and the relative dielectric constant of the adhesive sheet at a frequency of 100 Hz is 1000 or more.

3. The optical laminate according to claim 1, wherein the saturated moisture content of the adhesive sheet in an environment of 23°C and 55% RH is 2.0% by weight or less.

4. The optical laminate according to claim 1, wherein the saturated moisture content of the adhesive sheet in an environment of 85°C and 85% RH is 5.0% by weight or less.

5. The optical laminate according to claim 1, wherein the antistatic agent comprises an organic cation salt.

6. The optical laminate according to claim 1, wherein the polymer (A) is a (meth)acrylic polymer.

7. The optical laminate according to claim 1, wherein the polymer (A) has a polyether structure.

8. The optical laminate according to claim 1, wherein the polymer (A) has a structural unit derived from a monomer represented by formula (1), ， in formula (1), R 1 is a hydrogen atom or a methyl group, R 2 R is alkyl, optionally linear or having branches, n is an integer of 1 to 15.

9. The optical laminate according to claim 8, wherein in formula (1), n is an integer of 2 to 15.

10. The optical laminate according to claim 1, wherein the adhesive composition further comprises a peroxide-based crosslinking agent and a radical scavenger.

11. The optical laminate according to claim 10, wherein the radical scavenger is an antioxidant.

12. The optical laminate according to claim 1, wherein the adhesive composition further comprises an isocyanate-based crosslinking agent.

13. An image display panel comprising the optical laminate according to any one of claims 1 to 12.

14. An image display device comprising the image display panel according to claim 13.

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