Adhesive sheet for image display device constituent member, adhesive sheet with release film, adhesive sheet with image display device constituent member, laminated sheet, and image display device

Abstract

To provide an adhesive composition or sheet for image display components that has high endurance against light so that it can adapt to the reduced thickness or weight of image displays.SOLUTION: An adhesive sheet for image display components is formed from an adhesive composition containing a meth)acrylic copolymer (A), a benzophenone compound having a hydroxy group (B) and a radical polymerization initiator (C) and has a light transmittance of less than 30% at a wavelength of 400 nm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet for image display device components that can be suitably used for bonding image display device components, an adhesive sheet with a release film, an adhesive sheet with image display device components, a laminated sheet, and an image display device. [Background technology]

[0002] BACKGROUND ART In recent years, there has been a demand for thinner, lighter, and more highly functional image display devices such as liquid crystal display devices and organic electroluminescence (hereinafter also referred to as "organic EL") display devices.

[0003] As one way to improve the performance of image display devices, suppressing light degradation of various optical components is being considered, and one example is a known adhesive sheet containing an ultraviolet absorber that is placed between a surface protection panel and an image display module.

[0004] For example, Patent Document 1 discloses a pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer, b* of 0.42 or less, and transmittance of light with a wavelength of 350 nm of 5% or less. Furthermore, Patent Document 2 discloses an ultraviolet-curable acrylic pressure-sensitive adhesive layer that is disposed between a cover glass or cover plastic and a polarizing film in an image display device and has a transmittance of 40% or less at a wavelength of 380 nm and a transmittance of 30% or more at a wavelength of 400 nm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-214722 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-155981 Summary of the Invention [Problem to be solved by the invention]

[0006] The transparent pressure-sensitive adhesives for image display devices having a light-absorbing function disclosed in Patent Documents 1 and 2 complement the function of a protective film layer that protects a polarizing plate from ultraviolet rays, i.e., a protective film layer containing an ultraviolet absorber. Therefore, in order to respond to further reductions in the thickness and weight of image display devices, it is necessary to suppress light degradation of optical components without providing a protective film layer, and for this purpose, the pressure-sensitive adhesive itself needs to have light resistance reliability.

[0007] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive sheet for use as a component of an image display device, which has excellent light resistance reliability so as to be able to cope with the trend toward thinner and lighter image display devices. [Means for solving the problem]

[0008] To solve this problem, the present invention proposes an adhesive sheet for use as a component of an image display device, which is formed from an adhesive composition containing a (meth)acrylic copolymer (A), a hydroxy group-containing benzophenone compound (B), and a radical polymerization initiator (C), and which has a light transmittance of less than 30% at a wavelength of 400 nm. [Effects of the Invention]

[0009] The adhesive sheet for components of image display devices proposed by the present invention has excellent light resistance reliability, so there is no need to provide a protective film layer to protect the polarizing plate from ultraviolet rays, i.e., a protective film layer containing an ultraviolet absorber, as in the past, and the components of image display devices can be bonded together and integrated, and light degradation of the components of image display devices can also be prevented, which can contribute to making image display devices thinner, lighter, and moreover improving their light degradation resistance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an example of a pressure-sensitive adhesive sheet with image display device components of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of an image display device of the present invention. [Figure 3]1 is a cross-sectional view showing an example of an image display device of the present invention. [Figure 4] 1 is a cross-sectional view showing an example of an image display device of the present invention. [Figure 5] 1 is a cross-sectional view showing an example of an image display device of the present invention. [Figure 6] 1 is a cross-sectional view showing an example of a pressure-sensitive adhesive sheet with a release film of the present invention. [Figure 7] 1 is a cross-sectional view showing an example of a laminate sheet of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will now be described based on an embodiment, although the present invention is not limited to the embodiment described below.

[0012] <<Present adhesive composition>> An adhesive sheet for a component of an image display device according to one embodiment of the present invention (referred to as "the adhesive sheet") is an adhesive sheet formed from an adhesive composition (referred to as "the adhesive composition") containing a (meth)acrylic copolymer (A), a hydroxy group-containing benzophenone compound (B), and a radical polymerization initiator (C).

[0013] In the present invention, the term "(meth)acrylic polymer" encompasses acrylic copolymers and methacrylic copolymers, the term "(meth)acrylate" encompasses acrylates and methacrylates, and the term "(meth)acryloyl" encompasses acryloyl and methacryloyl.

[0014] Here, examples of the "image display device component" of the pressure-sensitive adhesive sheet for image display device components include, but are not limited to, a reflective sheet, a light guide plate and light source, a diffusion film, a prism sheet, a liquid crystal panel, a retardation plate, a glass substrate, a polarizing plate, an organic EL panel, an electrode, an anti-reflection film, a color filter, a touch sensor, a cover glass, a cover plastic, or a composite integrated of two or more of these components.

[0015] As described below, the pressure-sensitive adhesive composition may be one that is cured by heat or by active energy rays. In particular, one that is cured by active energy rays is preferred because it does not require aging and is excellent in productivity. The pressure-sensitive adhesive composition may be cured in multiple stages, as described below.

[0016] Furthermore, when curing with active energy rays, in the case of a pressure-sensitive adhesive sheet containing an ultraviolet absorber, the ultraviolet absorber interferes with curing with active energy rays, so it is usually difficult to adopt an active energy ray curing system. However, when this invention was applied, it was possible to obtain a good pressure-sensitive adhesive sheet.

[0017] <(Meth)acrylic polymer (A)> Examples of the (meth)acrylic polymer (A) include a homopolymer of alkyl (meth)acrylate, as well as a copolymer obtained by polymerizing a monomer component copolymerizable therewith.

[0018] An example of the copolymer is a copolymer of an alkyl (meth)acrylate (a1) having 4 to 18 carbon atoms in the alkyl group as the main component and a monomer component copolymerizable therewith. The above-mentioned main component means a component that has a significant effect on the properties of the (meth)acrylic polymer (A), and the content of the component is usually 30% by mass or more, preferably 35% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more of the total (meth)acrylic polymer (A).

[0019] The (meth)acrylic polymer (A) may contain two or more different types of (meth)acrylic polymers.

[0020] Examples of the "alkyl (meth)acrylate (a1) in which the alkyl group has 4 to 18 carbon atoms" include linear alkyl (meth)acrylates such as n-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, and stearyl (meth)acrylate; isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate; isopentyl (meth)acrylate; Examples of suitable acrylates include branched alkyl (meth)acrylates such as butyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and isostearyl (meth)acrylate, and alicyclic (meth)acrylates such as cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 3,5,5-trimethylcyclohexane (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.

[0021] From the viewpoint of improving stress relaxation properties and heat resistance reliability when formed into a pressure-sensitive adhesive sheet or pressure-sensitive adhesive layer, the content of the alkyl (meth)acrylate (a1) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, particularly preferably 60% by mass or more, and most preferably 65% ​​by mass or more, based on the total components of the (meth)acrylic polymer (A). Furthermore, from the viewpoint of suppressing a decrease in adhesive strength, the content of the alkyl (meth)acrylate (a1) is preferably 90 mass % or less, more preferably 85 mass % or less, even more preferably 80 mass % or less, particularly preferably 75 mass % or less, and most preferably 70 mass % or less, based on the total components of the (meth)acrylic polymer (A).

[0022] Examples of the monomer component copolymerizable with the alkyl (meth)acrylate (a1) having 4 to 18 carbon atoms in the alkyl group include a hydroxy group-containing monomer (a2), a (meth)acrylate monomer or vinyl ester monomer (a3) ​​having 1 to 3 carbon atoms in the alkyl group, a functional group-containing ethylenically unsaturated monomer (a4) (excluding the hydroxy group-containing monomer (a2)), and other copolymerizable monomers (a5).

[0023] Examples of the "hydroxy group-containing monomer (a2)" include hydroxy (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; oxyalkylene-modified monomers such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; primary hydroxy group-containing monomers such as 2-acryloyloxyethyl-2-hydroxyethyl phthalate; secondary hydroxy group-containing monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; and tertiary hydroxy group-containing monomers such as 2,2-dimethyl-2-hydroxyethyl (meth)acrylate. These may be used alone or in combination of two or more.

[0024] Among the above hydroxy group-containing monomers (a2), primary hydroxy group-containing monomers, particularly 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate, and especially 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred because they have an excellent balance between moist heat resistance and heat resistance.

[0025] From the viewpoint of improving moist heat resistance, the lower limit of the content of the hydroxy group-containing monomer (a2) is usually 3 mass% or more, preferably 5 mass% or more, more preferably 8 mass% or more, even more preferably 10 mass% or more, and particularly preferably 12 mass% or more, based on the total components of the (meth)acrylic polymer (A). On the other hand, the upper limit of the content of the hydroxy group-containing monomer (a2) is usually 60% by mass or less, preferably 45% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, from the viewpoint of suppressing the self-crosslinking reaction of the pressure-sensitive adhesive composition and improving processability and heat resistance reliability.

[0026] Examples of the "(meth)acrylate monomer or vinyl ester-based monomer (a3) ​​having an alkyl group with 1 to 3 carbon atoms" include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, vinyl propionate, vinyl acetate, etc. These monomers (a3) ​​may be used alone or in combination of two or more. Of the above-mentioned components (a3), it is preferable to use methyl (meth)acrylate and ethyl (meth)acrylate from the viewpoint of improving cohesive strength when used as an adhesive.

[0027] Furthermore, the lower limit of the content of the (a3) ​​component, when contained, is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, based on the total components of the (meth)acrylic polymer (A), from the viewpoint of improving cohesive strength when used as a pressure-sensitive adhesive. Furthermore, the upper limit of the content of the (a3) ​​component, when contained, is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total components of the (meth)acrylic polymer (A), from the viewpoint of improving processability.

[0028] Examples of the "functional group-containing ethylenically unsaturated monomer (a4)" include a functional group-containing monomer having a nitrogen atom, a carboxy group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, and a glycidyl group-containing monomer. Among these, functional group-containing monomers having a nitrogen atom are preferred in terms of imparting cohesive strength and crosslinking-promoting action, more preferably amino group-containing monomers and amide group-containing monomers, and even more preferably amino group-containing monomers.

[0029] Examples of the "amino group-containing monomer" as the "functional group-containing monomer having a nitrogen atom" include primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate and aminoethyl (meth)acrylate; secondary amino group-containing (meth)acrylates such as t-butylaminoethyl (meth)acrylate and t-butylaminopropyl (meth)acrylate; and tertiary amino group-containing (meth)acrylates such as ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, and dimethylaminopropylacrylamide.

[0030] Examples of the "amide group-containing monomer" include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, Nn-butyl(meth)acrylamide, diacetone(meth)acrylamide, and N,N'-methylenebis(meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-ethylmethylacrylamide, and N,N-diallyl(meth)acrylamide; hydroxyalkyl(meth)acrylamides such as N-hydroxymethyl(meth)acrylamide and N-hydroxyethyl(meth)acrylamide; and alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide and N-(n-butoxymethyl)(meth)acrylamide.

[0031] Examples of the "carboxy group-containing monomer" include (meth)acrylic acid, carboxylethyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxypropyl phthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, and monomethyl itaconate.

[0032] Examples of the "acetoacetyl group-containing monomer" include 2-(acetoacetoxy)ethyl (meth)acrylate and allyl acetoacetate.

[0033] Examples of the "isocyanate group-containing monomer" include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof. The isocyanate group may be protected with a blocking agent such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, or diethyl malonate.

[0034] Examples of the "glycidyl group-containing monomer" include glycidyl (meth)acrylate, allyl glycidyl (meth)acrylate, and the like.

[0035] These functional group-containing ethylenically unsaturated monomers (a4) may be used alone or in combination of two or more.

[0036] From the viewpoint of improving the heat resistance and light resistance of the pressure-sensitive adhesive composition, the upper limit of the content of the functional group-containing ethylenically unsaturated monomer (a4) is preferably 30 mass % or less, more preferably 20 mass % or less, even more preferably 10 mass % or less, and particularly preferably 5 mass % or less, based on the total components of the (meth)acrylic polymer (A).

[0037] The (meth)acrylic polymer (A) may contain other copolymerizable monomers (a5) as copolymerization components, if necessary.

[0038] Examples of the other copolymerizable monomers (a5) include aromatic (meth)acrylic acid ester monomers such as phenyl(meth)acrylate, benzyl(meth)acrylate, phenoxyethyl(meth)acrylate, phenyldiethylene glycol(meth)acrylate, phenoxypolyethylene glycol(meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate, and nonylphenol ethylene oxide adduct (meth)acrylate; 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, and 4-methacryloyloxybenzophenone. Examples of suitable vinyl monomers include (meth)acrylic acid ester monomers having a benzophenone structure, such as oxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof, as well as acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ethers, vinyltoluene, vinylpyridine, vinylpyrrolidone, dialkyl itaconate esters, dialkyl fumarate esters, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, and dimethylallyl vinyl ketone. These may be used alone or in combination of two or more.

[0039] The (meth)acrylic polymer (A) may have a photoactive moiety, such as a polymerizable carbon-carbon double bond group, introduced into its side chain. This allows the pressure-sensitive adhesive composition to be crosslinked by radical polymerization even if the pressure-sensitive adhesive composition does not contain a polyfunctional (meth)acrylate (D). Furthermore, the crosslinking sensitivity of the pressure-sensitive adhesive composition can be increased, allowing the pressure-sensitive adhesive composition to be crosslinked by irradiation with lower-energy active energy rays, thereby imparting cohesive strength and heat resistance.

[0040] Examples of a method for introducing a polymerizable carbon-carbon double bond group into the side chain of the (meth)acrylic polymer (A) include a method in which a copolymer containing the above-mentioned hydroxy group-containing monomer (a2) or functional group-containing ethylenically unsaturated monomer (a4) as a copolymerization component is prepared, and then a compound (a6) having a polymerizable carbon-carbon double bond group and a functional group reactive with these functional groups is subjected to a condensation or addition reaction while maintaining the activity of the polymerizable carbon-carbon double bond group.

[0041] Examples of combinations of these functional groups include an epoxy group (glycidyl group) and a carboxy group, an amino group and a carboxy group, an amino group and an isocyanate group, an epoxy group (glycidyl group) and an amino group, a hydroxy group and an epoxy group, and a hydroxy group and an isocyanate group. Among these combinations of functional groups, a combination of a hydroxy group and an isocyanate group is preferred because of the ease of reaction control. Of these, a combination in which the copolymer has a hydroxy group and the compound has an isocyanate group is preferred. Examples of the isocyanate compound having a polymerizable carbon-carbon double bond group include the above-mentioned 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

[0042] From the viewpoint of improving adhesiveness and stress relaxation properties, the amount of the compound (a6) added is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer (A).

[0043] From the viewpoint of obtaining a pressure-sensitive adhesive composition having high cohesive strength, the mass average molecular weight of the (meth)acrylic polymer (A) is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more. Furthermore, the upper limit of the mass average molecular weight of the (meth)acrylic polymer (A) is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less, from the viewpoint of obtaining a pressure-sensitive adhesive composition having high fluidity and stress relaxation properties.

[0044] <Hydroxy group-containing benzophenone compound (B)> The present adhesive composition contains a hydroxy group-containing benzophenone compound (B) as an ultraviolet absorber, thereby ensuring the light resistance reliability of the adhesive sheet itself while reducing light-induced degradation of components of the image display device. Since the pressure-sensitive adhesive composition contains the hydroxyl group-containing benzophenone compound (B), when photocuring, it is preferable to cure the composition with light having a wavelength other than the absorption wavelength of the ultraviolet-absorbing hydroxyl group-containing benzophenone compound (B).

[0045] Examples of the hydroxy group-containing benzophenone compound (B) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxytrihydridolate benzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sodium sulfoxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2-hydroxy-4-n-dodecyloxybenzophenone, and 2-hydroxy-4-methoxy-2'-carboxybenzophenone.

[0046] Furthermore, among these, dihydroxybenzophenone compounds such as 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2'-dihydroxy-4,4'-dimethoxy-5-sodium sulfoxybenzophenone are more preferred from the viewpoint of being able to block light up to the long wavelength region.

[0047] From the viewpoint of improving light resistance reliability, the lower limit of the content of the hydroxy group-containing benzophenone compound (B) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.5 parts by mass or more, particularly preferably 3 parts by mass or more, and most preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic polymer (A). On the other hand, from the viewpoint of suppressing bleed-out and improving yellowing resistance, the upper limit of the content of the hydroxy group-containing benzophenone compound (B) is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and most preferably 7 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer (A).

[0048] <Radical polymerization initiator (C)> The radical polymerization initiator (C) may be any as long as it is capable of releasing a substance that initiates radical polymerization upon at least one of irradiation with active energy rays such as light and heat. In particular, a photoradical polymerization initiator that can initiate a reaction upon irradiation with active energy rays such as light is preferred because it does not require aging during curing and has excellent productivity.

[0049] Examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and perbenzoic acid, and azo compounds such as azobisbutyronitrile.

[0050] On the other hand, photoradical polymerization initiators are broadly classified into two types based on the radical generation mechanism: photocleavage-type radical polymerization initiators, which can generate radicals by cleaving and decomposing the single bond of the photoradical polymerization initiator itself, and hydrogen abstraction-type photoradical polymerization initiators, which form an exciplex between the photoexcited initiator and the hydrogen donor in the system and can transfer hydrogen from the hydrogen donor.

[0051] Among these, photocleavage radical polymerization initiators are preferred because they decompose into different compounds when generating radicals upon irradiation with light, and once excited, they no longer function as a reaction initiator, and therefore do not remain as active species in the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet after the crosslinking reaction is complete, and there is no possibility of causing unexpected photodegradation or the like in the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet. On the other hand, hydrogen abstraction type photoradical polymerization initiators not only maintain their function as reaction initiators even after multiple light irradiations, but also do not produce decomposition products, unlike photocleavage type radical polymerization initiators, during the radical-generating reaction caused by irradiation with active energy rays such as ultraviolet rays. Therefore, they are less likely to become volatile components after the reaction is completed, and are therefore useful in that they can reduce damage to the adherend. Among the above photoradical polymerization initiators, it is preferable to select a photocleavage type radical polymerization initiator in the present pressure-sensitive adhesive composition from the viewpoint of ensuring the light resistance reliability of the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet.

[0052] When a photoradical polymerization initiator is used, from the viewpoint of avoiding reaction inhibition by the hydroxy group-containing benzophenone compound (B), it is preferable to use a visible light initiator that generates radicals and serves as the starting point for the crosslinking reaction of the present pressure-sensitive adhesive composition upon irradiation with visible light, light having wavelengths of at least 390 nm, 405 nm, and 410 nm, for example, light in the wavelength range of 380 nm to 700 nm. However, the visible light initiator may be one that generates radicals only upon irradiation with visible light, or may be one that generates radicals also upon irradiation with light in a wavelength range other than the visible light range.

[0053] The radical polymerization initiator (C) preferably has an absorption maximum at least in the wavelength region of 400 to 430 nm, from the viewpoint of suppressing discoloration of the pressure-sensitive adhesive sheet caused by the radical polymerization initiator (C) itself while avoiding reaction inhibition by the hydroxy group-containing benzophenone compound (B). The absorption maximum refers to the wavelength showing the maximum absorbance in the absorption spectrum.

[0054] Examples of the photocleavage type radical polymerization initiator include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), phenylglyoxylic Examples of the methyl benzoate include methyl benzoate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, and derivatives thereof. Among these, from the viewpoint of becoming decomposed products and losing color after the reaction, acylphosphine oxide-based photoinitiators such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)2,4,4-trimethylpentylphosphine oxide are preferred.

[0055] Examples of the hydrogen abstraction type photoradical polymerization initiator include bis(2-phenyl-2-oxoacetic acid)oxybisethylene, phenylglyoxylic acid methyl ester, a mixture of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]ethyl ester, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, camphorquinone, and derivatives thereof. Among these, any one or two selected from the group consisting of phenylglyoxylic acid methyl ester, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]ethyl ester and a mixture of oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]ethyl ester are preferred.

[0056] The photoradical polymerization initiator is not limited to the substances listed above. Any one of the photoradical polymerization initiators listed above or its derivatives may be used, or two or more may be used in combination. Furthermore, a visible light initiator may be mixed with a substance that generates radicals only upon irradiation with other light rays such as ultraviolet light. A thermal radical polymerization initiator and a photoradical polymerization initiator may be used in combination.

[0057] The content of the radical polymerization initiator (C) is not particularly limited, but from the viewpoint of sufficiently progressing the polymerization reaction and improving the shape stability of the pressure-sensitive adhesive sheet, it is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 2 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A). Furthermore, from the viewpoint of ensuring adhesiveness, the upper limit of the content of the radical polymerization initiator (C) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 6 parts by mass or less, and particularly preferably 4 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer (A).

[0058] Furthermore, from the viewpoint of ensuring a balance of performance between the light resistance reliability and shape stability of the adhesive sheet itself, the mass ratio of the hydroxy group-containing benzophenone compound (B) to the radical polymerization initiator (C) is preferably (B):(C) = 1:0.05 to 1:20, more preferably 1:0.1 to 1:10, and even more preferably 1:0.3 to 1:2.

[0059] <Polyfunctional (meth)acrylate (D)> The present pressure-sensitive adhesive composition preferably contains a polyfunctional (meth)acrylate (D) as needed. The pressure-sensitive adhesive composition contains the polyfunctional (meth)acrylate (D), which allows the pressure-sensitive adhesive composition to form a crosslinked structure, imparting cohesive strength and appropriate toughness to the pressure-sensitive adhesive sheet. The appropriate toughness of the pressure-sensitive adhesive sheet can prevent the surface of the image display device component from undulating and the pressure-sensitive adhesive layer from deforming and cracking when cut when producing the image display device component with the pressure-sensitive adhesive layer described below.

[0060] The polyfunctional (meth)acrylate (D) is a compound or composition that forms a crosslinked structure in the present pressure-sensitive adhesive composition, and examples thereof include (meth)acrylic monomers and (meth)acrylic oligomers having two or more functional groups.

[0061] Examples of the (meth)acrylic monomer include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A polypropionate, and the like. Dioxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl(meth)acrylate, ε-caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate Pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, (tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol Examples of the hydroxypivalic acid diacrylate include trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol penta(meth)acrylate, neopentyl glycol hydroxypivalic acid di(meth)acrylate, di(meth)acrylate of an ε-caprolactone adduct of neopentyl glycol hydroxypivalic acid, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Among these, (meth)acrylic monomers are preferred from the viewpoint of imparting appropriate toughness to the cured product, and among these, polyfunctional (meth)acrylic monomers having an alkylene glycol skeleton, such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate, are more preferred.

[0062] From the viewpoint of imparting appropriate flexibility to the cured product, the molecular weight of the (meth)acrylic monomer is preferably 200 or more, more preferably 300 or more, even more preferably 400 or more, and particularly preferably 500 or more. The upper limit of the molecular weight is usually 3,000 or less, and preferably 2,000 or less.

[0063] Examples of the (meth)acrylic oligomer include polyfunctional (meth)acrylic oligomers such as polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate. Among these, urethane (meth)acrylate oligomers are preferred from the viewpoint of imparting appropriate toughness to the cured product.

[0064] Furthermore, from the viewpoint of being able to obtain a cured product with high toughness when the pressure-sensitive adhesive composition is cured with visible light, in other words, being able to obtain a cured product with appropriate flexibility, the polyfunctional (meth)acrylate (D) is preferably a (meth)acrylic oligomer having a molecular weight of 3,000 or more, and particularly preferably a polyfunctional (meth)acrylate having a molecular weight of 5,000 or more, of which 8,000 or more, of which 10,000 or more. The upper limit of such molecular weight is usually 100,000 or less, preferably 50,000 or less.

[0065] The content by mass of the polyfunctional (meth)acrylate (D) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the (meth)acrylic polymer (A), from the viewpoint of being able to impart shape stability to the pressure-sensitive adhesive sheet and durability when a laminate is formed from the pressure-sensitive adhesive sheet. The upper limit of the content by mass of the polyfunctional (meth)acrylate (D) is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, per 100 parts by mass of the (meth)acrylic polymer (A), from the viewpoint of ensuring adhesiveness.

[0066] <Other ingredients> The present pressure-sensitive adhesive composition may contain, as "other components", various additives such as a tackifying resin, an antioxidant, a light stabilizer, a metal deactivator, an anti-aging agent, a moisture absorbent, a rust inhibitor, a silane coupling agent, and inorganic particles, as needed. If necessary, a reaction catalyst such as a tertiary amine compound, a quaternary ammonium compound, or a tin laurate compound may be appropriately contained.

[0067] <Curability> The present pressure-sensitive adhesive composition can be cured in one step or in multiple steps. That is, it can be cured while leaving room for further curing. In terms of gel fraction, the gel fraction of the present pressure-sensitive adhesive composition can be 60% or more in one curing step, or it can be cured with a gel fraction of 20 to 60% in the first curing step, leaving room for further curing. For example, when the present pressure-sensitive adhesive composition is active energy ray-curable, after laminating it with a component of an image display device or after forming a laminate with a component of an image display device and another component of an image display device, the composition can be cured by irradiating it with light, thereby more firmly adhering the component of the image display device and the other component of an image display device, thereby improving the reliability of the laminate. The light source used is preferably ultraviolet light or visible light from the viewpoint of suppressing damage to components of the image display device and controlling reactions. The irradiation time and irradiation means are not particularly limited, but it is preferable to irradiate the image display device components from the side opposite to the lamination surface.

[0068] Furthermore, the irradiation energy, irradiation time, irradiation method, etc. of the active energy ray are not particularly limited as long as they can activate the initiator and polymerize the (meth)acrylate component.

[0069] <Light transmittance> From the viewpoint of preventing light degradation of components of an image display device when a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is used in combination with the components, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and having a thickness of 50 μm preferably has a transmittance at a wavelength of 400 nm of less than 30%, more preferably 25% or less, even more preferably 22% or less, and particularly preferably 20% or less.

[0070] Furthermore, from the viewpoint of preventing light degradation of components of an image display device when a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is used in combination with the components of the image display device, the transmittance of a 50 μm-thick pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition at a wavelength of 380 nm is preferably less than 20%, more preferably 5% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0071] Furthermore, from the viewpoint of ensuring sufficient image visibility when an adhesive layer formed from the present adhesive composition is used in an image display device, the transmittance at a wavelength of 430 nm of an adhesive layer having a thickness of 50 μm formed from the present adhesive composition is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and especially preferably 85% or more.

[0072] <<This adhesive sheet>> An adhesive sheet for an image display device component according to one embodiment of the present invention (referred to as "the adhesive sheet") is an adhesive sheet including an adhesive layer (referred to as "the adhesive layer") formed using the adhesive composition.

[0073] The present pressure-sensitive adhesive sheet may have a single layer structure consisting of the present pressure-sensitive adhesive layer formed using the present pressure-sensitive adhesive composition, or may have a multi-layer structure consisting of two or more layers including a layer other than the pressure-sensitive adhesive layer. When the present pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers, the composition of the layers other than the layer made of the present pressure-sensitive adhesive composition is optional. However, for example, when an intermediate layer, outermost layer, or innermost layer is formed from a layer other than the present pressure-sensitive adhesive layer, from the viewpoint of further improving interlayer adhesion, the pressure-sensitive adhesive composition forming the layer other than the present pressure-sensitive adhesive layer is preferably formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer as the main component resin, and more preferably contains the same (meth)acrylic polymer (A) as the present pressure-sensitive adhesive layer as the main component resin. Furthermore, it is more preferable that the layer other than the present pressure-sensitive adhesive layer also contains a polyfunctional (meth)acrylate and a radical polymerization initiator.

[0074] When the present pressure-sensitive adhesive sheet has a multi-layer structure of two or more layers, it is preferable that at least the outermost layer, the innermost layer, or both of these layers are layers that correspond to the present pressure-sensitive adhesive layer, although all layers may be layers that correspond to the present pressure-sensitive adhesive layer. When the adhesive sheet has a multi-layer structure of two or more layers, it is preferable that the thickness of the layer corresponding to the adhesive layer accounts for 10% or more and 100% or less of the total thickness of the adhesive sheet, and more preferably 14% or more or 70% or less, and even more preferably 20% or more or 50% or less.

[0075] (Light transmittance) From the viewpoint of preventing light deterioration of image display device components when used in combination with the present adhesive layer or the present adhesive sheet, the transmittance at a wavelength of 400 nm is preferably less than 30%, more preferably 25% or less, even more preferably 22% or less, and particularly preferably 20% or less.

[0076] Furthermore, from the viewpoint of preventing light deterioration of image display device components when used in combination with the present adhesive layer or the present adhesive sheet, the transmittance at a wavelength of 380 nm is preferably less than 20%, more preferably 5% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0077] Furthermore, from the viewpoint of ensuring sufficient image visibility when used in an image display device, the present adhesive layer or the present adhesive sheet preferably has a light transmittance at a wavelength of 430 nm of 50% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and especially preferably 85% or more.

[0078] (b * value) From the viewpoint of suppressing adverse effects on image quality when used in an image display device, the present adhesive layer or the present adhesive sheet is * The value is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.0 or less, and particularly preferably 1.8 or less. Above b * The value is the L specified in JIS Z8781-4. * a * b * b in the display color space * This is the value of , and an increase in the positive side means that the color is yellowish, an increase in the negative side means that the color is blueish, and as it approaches 0, the color becomes achromatic.

[0079] In addition, the adhesive layer or the adhesive sheet has a light transmittance T(380) at a wavelength of 380 nm, a light transmittance T(430) at a wavelength of 430 nm, and b * It is preferable that the values ​​satisfy the relationships of the following formulas (I) and (II). 0 ≦ T(380)×b * ≦50 (I) 70≦ T(430)×b * ≦220 (II)

[0080] When the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet satisfies the relationships of the above formulas (I) and (II), it is possible to prevent light degradation of components of an image display device and to achieve a higher level of image visibility of the image display device at the same time. From this viewpoint, T(380)×b in the above formula (I) * is preferably 0 to 50, more preferably 0 to 40, even more preferably 0 to 30, and particularly preferably 0 to 20. T(430)×b in the above formula (II) * is preferably 70 to 220, more preferably 80 or more or 210 or less, further preferably 90 or more or 200 or less, and particularly preferably 100 or more or 190 or less.

[0081] In the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive sheet, the light transmittance at wavelengths of 380 nm, 400 nm, and 430 nm, and b * To adjust the value to the above range, it is preferable to appropriately adjust the type and amount of the hydroxyl group-containing benzophenone compound (B), although this is not limitative.

[0082] (gel fraction) The pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet preferably has a gel fraction of 20% or more when used for adhesion, which can provide shape stability to the pressure-sensitive adhesive sheet and durability when used as a laminate. From this viewpoint, the gel fraction of the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive sheet is more preferably 40% or more, even more preferably 50% or more, and particularly preferably 60% or more. On the other hand, if the gel fraction is 95% or less, even if the adherend is a member having a stepped portion on its surface, the composition can conform to the stepped portion and fill every corner without causing distortion or deformation to the member. From this viewpoint, the gel fraction is preferably 95% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less.

[0083] In order to adjust the gel fraction of the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive sheet to fall within the above range when used for adhesion, it is preferable to adjust the composition or molecular weight of the (meth)acrylic polymer (A), adjust the amount of polyfunctional (meth)acrylate (D) or radical polymerization initiator (C) added, or adjust the intensity or integrated light amount of the irradiated active energy rays, although this is not limitative.

[0084] (Thickness) The thickness of the pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly preferably 40 μm or more, from the viewpoint of protecting components of an image display device, while the upper limit of the thickness is preferably 175 μm or less, more preferably 120 μm or less, even more preferably 80 μm or less, and particularly preferably 60 μm or less, from the viewpoint of contributing to the thinning of an image display device.

[0085] <Method of manufacturing the present pressure-sensitive adhesive sheet> Next, a method for producing the present pressure-sensitive adhesive sheet will be described. However, the following description is an example of a method for producing the present pressure-sensitive adhesive sheet, and the present pressure-sensitive adhesive sheet is not limited to sheets produced by this method.

[0086] The present pressure-sensitive adhesive sheet can be produced by mixing predetermined amounts of the (meth)acrylic polymer (A), the hydroxyl group-containing benzophenone compound (B), and the radical polymerization initiator (C), as well as, if necessary, the polyfunctional (meth)acrylate (D), and, if necessary, other components, to prepare the present pressure-sensitive adhesive composition, forming the present pressure-sensitive adhesive composition into a sheet, and, if necessary, curing the curable compound by crosslinking, i.e., polymerizing, the composition to produce the present pressure-sensitive adhesive sheet, although the present invention is not limited to this method.

[0087] When preparing the present pressure-sensitive adhesive composition, the above raw materials may be kneaded using a temperature-controllable kneader (for example, a single-screw extruder, a twin-screw extruder, a planetary mixer, a twin-screw mixer, a pressure kneader, etc.). When mixing various raw materials, the various additives may be blended together with the resin in advance and then supplied to the kneader, or all of the materials may be melt-mixed in advance and then supplied, or a master batch in which only the additives are concentrated in the resin may be prepared and then supplied.

[0088] The pressure-sensitive adhesive composition can be formed into a sheet by known methods such as wet lamination, dry lamination, extrusion casting using a T-die, extrusion lamination, calendaring, inflation, injection molding, and liquid injection curing. Of these, when producing a sheet, wet lamination, extrusion casting, and extrusion lamination are preferred.

[0089] Furthermore, when the present pressure-sensitive adhesive composition contains a radical polymerization initiator (C), it can be cured by irradiating it with heat and / or active energy rays to produce a cured product. In particular, the present pressure-sensitive adhesive sheet can be produced by irradiating a molded article, such as a sheet, of the present pressure-sensitive adhesive composition with heat and / or active energy rays. Examples of the active energy rays to be irradiated include ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, as well as ultraviolet rays and visible light rays. Among these, ultraviolet rays and visible light rays are preferred from the viewpoints of suppressing damage to optical device components and controlling reactions. Furthermore, the irradiation energy, irradiation time, irradiation method, etc. of the active energy ray are not particularly limited as long as they can activate the initiator and polymerize the (meth)acrylate component.

[0090] In another embodiment of the method for producing the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition can be dissolved in an appropriate solvent and then coated using various coating techniques. When a coating method is used, the present pressure-sensitive adhesive sheet can also be obtained by heat curing in addition to the above-mentioned active energy ray irradiation curing.

[0091] In the case of coating, the thickness of the pressure-sensitive adhesive sheet can be adjusted by the coating thickness and the solids concentration of the coating liquid.

[0092] <<Adhesive sheet with release film>> The present pressure-sensitive adhesive sheet can also be made into a pressure-sensitive adhesive sheet with a release film (referred to as "the present pressure-sensitive adhesive sheet with a release film") having a configuration in which the present pressure-sensitive adhesive sheet and a release film are laminated together. For example, a single-layer or multi-layer sheet-like adhesive layer containing a layer made of the present adhesive composition can be formed on a release film to form an adhesive sheet with a release film (see FIG. 6).

[0093] As the material for such a release film, any known release film can be used appropriately. The material for the release film may be, for example, a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a triacetyl cellulose film, a fluororesin film, or the like, which has been subjected to a release treatment by coating with a silicone resin, or release paper, or the like. The film may have other layers, such as an antistatic layer, a hard coat layer, or an anchor layer, as required.

[0094] When release films are laminated on both sides of the present pressure-sensitive adhesive sheet, one release film may have the same layer structure or material as the other release film, or may have a different layer structure or material. They may also be of the same thickness or of different thicknesses. Furthermore, release films with different peel strengths or thicknesses can be laminated on both sides of the pressure-sensitive adhesive sheet.

[0095] The thickness of the release film is not particularly limited, but from the viewpoint of processability and handleability, it is preferably 12 μm to 250 μm, more preferably 25 μm or more or 200 μm or less, and even more preferably 38 μm or more or 188 μm or less.

[0096] The present pressure-sensitive adhesive sheet can also be produced by, for example, directly extruding the present resin composition or by injecting the composition into a mold, without using an adherend or a release film as described above. Furthermore, the present pressure-sensitive adhesive sheet can also be formed by directly filling the present resin composition between the adherends, which are constituent members for an image display device.

[0097] <<This laminated sheet>> A laminate sheet (referred to as "the present laminate sheet") as an example of an embodiment of the present invention comprises the present pressure-sensitive adhesive sheet having a resin sheet or thin film glass on at least one side thereof (see FIG. 7).

[0098] Examples of the resin sheet include a resin sheet containing one or more resins selected from the group consisting of cycloolefin resin, triacetyl cellulose resin, polymethyl methacrylate resin, epoxy resin, polyester resin, and polyimide resin as the main component resin. In this case, the main component resin means the resin with the highest mass proportion among the resins constituting the resin sheet, and is a resin that accounts for 50 mass% or more, particularly 60 mass% or more, particularly 70 mass% or more, particularly 80 mass% or more, particularly 90 mass% or more, particularly 95 mass% or more (including 100 mass%) of the resins constituting the resin sheet.

[0099] Examples of the thin film glass include glass having bending resistance, such as ultra-thin glass (G-Leaf, manufactured by Nippon Electric Glass Co., Ltd.).

[0100] <<Image display device component with the present adhesive layer>> An image display device component with a pressure-sensitive adhesive layer (referred to as "the image display device component with the present pressure-sensitive adhesive layer") as one example of an embodiment of the present invention is an image display device component with a pressure-sensitive adhesive layer, which comprises a pressure-sensitive adhesive layer (referred to as "the present pressure-sensitive adhesive layer") formed from the present pressure-sensitive adhesive composition or the present pressure-sensitive adhesive sheet on at least one side of the image display device component.

[0101] The present pressure-sensitive adhesive layer-attached image display device constituent member may be, for example, a pressure-sensitive adhesive sheet with an image display device constituent member provided on at least one side of the present pressure-sensitive adhesive sheet.

[0102] The present pressure-sensitive adhesive layer-attached constituent member of an image display device may be a pressure-sensitive adhesive layer-attached constituent member of an image display device provided on at least one side of the present pressure-sensitive adhesive layer. In this case, the pressure-sensitive adhesive layer may be directly formed on a component of the image display device, or a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition may be formed on another substrate, and then the pressure-sensitive adhesive layer may be transferred onto a component of the image display device.

[0103] Furthermore, the image display device component with the present pressure-sensitive adhesive layer may have a structure in which the image display device component and the present pressure-sensitive adhesive layer or the present pressure-sensitive adhesive sheet are directly laminated together, or another member may be interposed between them. In either case, the effects of the present invention can be enjoyed. In this case, examples of the "other components" include a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a liquid crystal panel, a retardation plate, a glass substrate, a polarizing plate, an organic EL panel, an electrode, an anti-reflection film, a color filter, a touch sensor, a cover glass, a cover plastic, or a composite integrated combination of two or more of these components. In addition to the above-mentioned members, other layers may be interposed as necessary, such as an antistatic layer, a hard coat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, and a flattening layer.

[0104] <Image display device components using coated polarizing elements> An example of a component of an image display device is an optical component using a coating type polarizing element. A coating-type polarizing element is a laminate including a film formed by coating an optically anisotropic composition containing a liquid crystal compound. For example, an optically anisotropic composition containing a liquid crystal compound is coated on an alignment film formed on a substrate, the optically anisotropic composition is aligned, and the aligned composition is cured to form an optically anisotropic layer. Various optically anisotropic members can then be produced using this substrate-attached optically anisotropic layer, or an optically anisotropic layer peeled from the substrate. The optically anisotropic member may have an optically anisotropic layer made of an optically anisotropic composition and an alignment film. Alternatively, it may have only an optically anisotropic layer without an alignment film. Examples of the liquid crystal compound include a polymerizable liquid crystal compound, a polymer liquid crystal compound, and a lyotropic liquid crystal compound.

[0105] Conventional polarizing plates generally have a structure in which a polyvinyl alcohol (PVA) film is sandwiched between protective films such as triacetyl cellulose (TAC) film, and then an adhesive is applied to the film or an adhesive sheet is laminated on top. However, in the case of a polarizing plate using an optically anisotropic layer made of a coating type polarizing element, the film can be formed by coating, and therefore the thickness can be made thinner than that of conventional polarizing elements.

[0106] Conventional retardation plates are generally obtained by stretching a resin sheet such as polycarbonate, but there is a limit to how thin the sheet can be made because the sheet is prone to breakage if it is made too thin. However, a retardation plate using an optically anisotropic layer made of a coating type polarizing element can be made thinner than a conventional stretched sheet, and therefore the thickness can be reduced.

[0107] By using a polarizing plate made of such a coating type polarizing element and / or a circular polarizing plate using a retardation plate in an image display device, it is possible to contribute to making the image display device thinner.

[0108] Examples of the "substrate" for forming a coating-type polarizing element include glass or a resin sheet containing, as a main component, one or more resins selected from the group consisting of polyolefin resins, cyclic polyolefin resins, polyester resins, poly(meth)acrylic acid ester resins, cellulose ester resins, polycarbonate resins, and polyimide resins. If necessary, other layers may be provided on the substrate, such as an antistatic layer, a hard coat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, and a flattening layer.

[0109] The liquid crystal compound can be aligned by a method using an alignment control force of an alignment film provided on a substrate, an alignment control force due to an external field such as an electric field or a magnetic field, and / or a shear force during coating. In particular, the method using an alignment film is preferred from the viewpoint of achieving a highly ordered alignment of the polymerizable liquid crystal compound and obtaining a coatable polarizing element that exhibits good optical performance.

[0110] The alignment film provided on the substrate is a layer having an alignment regulating force for aligning a polymerizable liquid crystal compound described later in a desired direction. The alignment film preferably has solvent resistance so that the optically anisotropic composition solution is not dissolved when applied, moderate solution affinity so that the optically anisotropic composition solution is not repelled, and heat resistance in the heating treatment during solvent drying and liquid crystal alignment. The alignment film may be subjected to an alignment treatment to control the alignment direction. In this case, examples of the alignment treatment method include known methods described on pages 226 to 239 of "Liquid Crystal Handbook" (Maruzen Co., Ltd., published October 30, 2000) (rubbing method, method of forming grooves (fine groove structures) on the surface of the alignment film, method using polarized ultraviolet light or polarized laser (photoalignment method), alignment method by forming an LB film, alignment method by oblique deposition of inorganic material, etc.). In particular, rubbing method and photoalignment method are preferred from the viewpoint of easily achieving a high degree of alignment. The thickness of the alignment film is usually 10 nm to 1000 nm, preferably 50 nm to 800 nm. When the thickness is within this range, it is possible to achieve both an alignment control force sufficient to align the polymerizable liquid crystal compound and thinning of the film.

[0111] The optically anisotropic composition may be a composition that contains, in addition to the liquid crystal compound, a polymerization initiator, and if necessary, various additives such as a polymerization inhibitor, a polymerization aid, a polymerizable non-liquid crystal compound, a surfactant, a leveling agent, a coupling agent, a pH adjuster, a dispersant, an antioxidant, an organic or inorganic filler, or a metal oxide, and a solvent, and a cured layer of this composition exhibits the optical function as a polarizing element.

[0112] When the polarizing element is a polarizing film, the optically anisotropic composition preferably contains a dichroic dye, such as iodine or a dichroic organic dye. The dichroic dye may be one type or a combination of different dyes. The dichroic organic dye is not particularly limited, but examples thereof include azo dyes, quinone dyes (including naphthoquinone dyes, anthraquinone dyes, etc.), stilbene dyes, cyanine dyes, phthalocyanine dyes, indigo dyes, condensed polycyclic dyes (including perylene dyes, oxazine dyes, acridine dyes, etc.), etc. Among these dyes, azo dyes are preferred because they have a large molecular long-to-short axis ratio and can exhibit good dichroism.

[0113] (Polymerizable liquid crystal compound) The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group, and has both the properties of a polymerizable monomer and the properties of a liquid crystal, so that the alignment can be fixed by crosslinking the polymerizable functional group in an aligned state of the liquid crystal, thereby exhibiting optical anisotropy. The polymerizable liquid crystal compound used may be one type, or a combination of multiple compounds with different structures. The polymerizable liquid crystal compound may be either a low molecular weight liquid crystal compound having a polymerizable functional group or a high molecular weight liquid crystal compound having a polymerizable functional group. Among them, a low molecular weight liquid crystal compound is preferred because a polymerizable liquid crystal compound tends to easily give a cured product exhibiting high alignment. The liquid crystal phase exhibited by the polymerizable liquid crystal compound can be appropriately selected from nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, discotic liquid crystal, etc., but from the viewpoint of ease of production and obtaining a highly ordered orientation state, it is preferable that the polymerizable liquid crystal compound exhibits nematic liquid crystal or smectic liquid crystal. The polymerizable functional group is preferably a photopolymerizable group because it is easy to fix the orientation structure.Specific examples include an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, an acryloylamino group, a methacryloylamino group, a vinyl group, a vinyloxy group, an ethynyl group, an ethynyloxy group, a 1,3-butadienyl group, a 1,3-butadienyloxy group, an oxiranyl group, an oxetanyl group, a glycidyl group, a glycidyloxy group, a styryl group, and a styryloxy group.Among these, a (meth)acryloyl group is preferred.

[0114] The polymerizable liquid crystal compound is not particularly limited in molecular structure, and any liquid crystal compound having a polymerizable group can be used. For example, the polymerizable liquid crystal compound contained in the optically anisotropic composition may be a compound represented by the following formula (1) (hereinafter, sometimes referred to as "polymerizable liquid crystal compound (1)").

[0115] Q 1 -R 1 -A 11 -Y 1 -A 12 -(Y 2 -A 13 ) k -R 2 -Q 2 ···(1)

[0116] (In formula (1), -Q 1 represents a hydrogen atom or a polymerizable group; -Q 2 represents a polymerizable group; -R 1 - and R 2 - each independently represents a chain organic group; -A 11 - and A 13- each independently represents a partial structure represented by the following formula (2), a divalent organic group, or a single bond: -A 12 - represents a partial structure represented by the following formula (2) or a divalent organic group; -Y 1 - and Y 2 - each independently represents a single bond, -C(=O)O-, -OC(=O)-, -C(=S)O-, -OC(=S)-, -C(=O)S-, -SC(=O)-, -CHCH-, -CH=CH-, -C≡C-, -C(=O)NH-, -NHC(=O)-, -CHO-, -OCH-, -CHS-, or SCH-; -A 11 - and A 13 - is a partial structure represented by the following formula (2) or a divalent organic group: k is 1 or 2. If k is 2, two -Y 2 -A 13 - may be the same or different.)

[0117] -Cy-X 2 -C≡CX 1 -···(2)

[0118] (In formula (2), -Cy- represents a hydrocarbon ring group or a heterocyclic group; -X 1 - represents -C(=O)O-, -OC(=O)-, -C(=S)O-, -OC(=S)-, -C(=O)S-, -SC(=O)-, -CH2CH2-, -CH=CH-, -C(=O)NH-, -NHC(=O)-, -C2O-, -OCH2-, -CH2S-, or SCH2-; -X 2 - represents a single bond, -C(=O)O-, -OC(=O)-, -C(=S)O-, -OC(=S)-, -C(=O)S-, -SC(=O)-, -CHCH-, -CH=CH-, -C(=O)NH-, -NHC(=O)-, -CHO-, -OCH-, -CHS-, or SCH-.

[0119] In addition, -A 11When - is a partial structure represented by formula (2), formula (1) may be the following formula (1A) or the following formula (1B). Q 1 -R 1 -Cy-X 2 -C≡CX 1 -Y 1 -A 12 -(Y 2 -A 13 ) k -R 2 -Q 2 (1A) Q 1 -R 1 -X 1 -C≡CX 2 -Cy-Y 1 -A 12 -(Y 2 -A 13 ) k -R 2 -Q 2 (1B)

[0120] Also, -A 12 When - is a partial structure represented by formula (2), formula (1) may be the following formula (1C) or the following formula (1D). Q 1 -R 1 -A 11 -Y 1 -Cy-X 2 -C≡CX 1 -(Y 2 -A 13 ) k -R 2 -Q 2 (1C) Q 1 -R 1 -A 11 -Y 1 -X 1 -C≡CX 2 -Cy-(Y 2 -A 13 ) k -R 2 -Q 2 (1D)

[0121] Also, -A 13When - is a partial structure represented by formula (2), formula (1) may be the following formula (1E) or the following formula (1F). Q 1 -R 1 -A 11 -Y 1 -A 12 -(Y 2 -Cy-X 2 -C≡CX 1 ) k -R 2 -Q 2 ···(1E) Q 1 -R 1 -A 11 -Y 1 -A 12 -(Y 2 -X 1 -C≡CX 2 -Cy) k -R 2 -Q 2 ···(1F)

[0122] Similarly, -A 11 -, -A 12 - and A 13 - When two or more of the partial structures are partial structures represented by formula (2), the orientation of each partial structure represented by formula (2) may be inverted.

[0123] Also, as mentioned above, -A 11 -, -A 12 - and A 13 - is independently a partial structure represented by formula (2) or a divalent organic group, and -A 11 - and A 13 - may be a single bond, but -A 11 - and A 13 -, but neither of them is a single bond.

[0124] As the polymerizable liquid crystal compound (1), a compound represented by the above formula (1A), (1B), (1E) or (1F) is preferred because it tends to provide high alignment.

[0125] When the polymerizable liquid crystal compound is photopolymerized, it is preferable that the optically anisotropic composition contains a photopolymerization initiator. Any known photopolymerization initiator can be used.

[0126] The thickness of the cured film of the optically anisotropic composition is preferably 100 nm or more, more preferably 300 nm or more, and even more preferably 1 μm or more, from the viewpoint of ensuring optical functionality. On the other hand, the upper limit of the thickness is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less, from the viewpoint of contributing to thinner image display devices.

[0127] On the cured film of the optically anisotropic composition, other layers may be formed as needed, such as an overcoat layer, an antistatic layer, a hard coat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, or a flattening layer.

[0128] <<Adhesive sheet with components of the image display device>> An adhesive sheet with an image display device component (referred to as "the adhesive sheet with the image display device component of the present invention") as an example of an embodiment of the present invention is configured to have the present adhesive sheet on at least one side of an image display device component, in other words, to have an image display device component on at least one side of the present adhesive sheet.

[0129] The present adhesive sheet with image display device components can be obtained, for example, by a method in which an image display device component is formed on a substrate having releasability, and then the image display device component is transferred to the surface of the present adhesive sheet, a method in which the present adhesive sheet is molded directly onto an image display device component, or a method in which the image display device component is formed on the present adhesive sheet.

[0130] Furthermore, the present pressure-sensitive adhesive sheet with image display device constituent members may have a structure in which the image display device constituent members and the present pressure-sensitive adhesive sheet are directly laminated together, or may have another member interposed between them. In either case, the effects of the present invention can be enjoyed. In this case, examples of the "other components" include a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a liquid crystal panel, a retardation plate, a glass substrate, a polarizing plate, an organic EL panel, an electrode, an anti-reflection film, a color filter, a touch sensor, a cover glass, a cover plastic, or a composite integrated combination of two or more of these components.

[0131] The image display device constituent member of the present pressure-sensitive adhesive sheet with image display device constituent member is the same as the image display device constituent member of the present pressure-sensitive adhesive layer-attached image display device constituent member.

[0132] <<This image display device>> An image display device according to one embodiment of the present invention (referred to as "the present image display device") is an image display device that includes the present pressure-sensitive adhesive layer. The present pressure-sensitive adhesive layer is not limited in its form, and may be a sheet-like pressure-sensitive adhesive product that has been formed into a sheet in advance, that is, the present pressure-sensitive adhesive sheet. An example of the present image display device is an image display device having a structure in which the present pressure-sensitive adhesive layer made of the present pressure-sensitive adhesive composition, an image display device component, and, if necessary, further other components, for example, other image display device components, are combined and laminated.

[0133] In the present image display device, the image display device constituent member and the present pressure-sensitive adhesive layer may be directly laminated as shown in Fig. 2 or 4, or another member, for example, another image display device constituent member may be interposed between them as shown in Fig. 3. In either case, the effects of the present invention can be enjoyed. In this case, examples of "other components of the image display device" include a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, the present laminate, a liquid crystal panel, a retardation film, a glass substrate, a polarizing plate, an organic EL panel, an electrode, an anti-reflection film, a color filter, a touch sensor, a cover glass, a cover plastic, or a composite integrated product of two or more of these components. In addition to the above-mentioned members, other layers may be interposed as necessary, such as an antistatic layer, a hard coat layer, an anchor layer, a release layer, an easy-adhesion layer, a protective layer, a bleeding prevention layer, and a flattening layer.

[0134] The pressure-sensitive adhesive layer in the image display device is preferably disposed on the viewing side of the image display device constituent member that is the adherend. Specifically, the pressure-sensitive adhesive layer is preferably used to attach a cover glass or a cover plastic. This can suppress deterioration of the polarizing element due to incident light from outside.

[0135] In an organic EL display device (see Figure 5) equipped with the present adhesive layer, when the organic EL panel has a structure in which a color filter, a black matrix, and optionally an anti-reflection layer are integrated (a color filter-integrated organic EL panel), the present adhesive layer or the present adhesive sheet is preferably positioned on the viewing side of the organic EL panel. The color filter-embedded organic EL panel reduces external light reflection through the color filter, black matrix, and anti-reflection layer built into the panel, eliminating the need for the polarizing plate and retardation plate (circular polarizing plate) used in conventional organic EL panels, thereby contributing to further thinning and weight reduction of image display devices. Furthermore, the organic EL panel with built-in color filters eliminates the loss of light emitted from the organic EL elements due to the circular polarizer absorbing the light emitted from the organic EL elements, dramatically improving the luminous efficiency of the organic EL elements and ultimately the luminous lifespan of the organic EL elements, thereby contributing to further improving the performance of image display devices. By arranging the pressure-sensitive adhesive layer or the pressure-sensitive adhesive sheet on the viewing side of the organic EL panel, deterioration of the organic EL panel due to incident light from outside can be suppressed.

[0136] Specific examples of the image display device include a liquid crystal display, an organic EL display, an inorganic EL display, electronic paper, a plasma display, and a microelectromechanical system (MEMS) display.

[0137] The present laminate sheet described above can also be used on the surface of the cover glass or cover plastic of the present image display device.

[0138] The pressure-sensitive adhesive layer has the above-mentioned light transmittance, b * The adhesive sheet has the value, gel fraction and thickness properties, and can enjoy the preferred ranges of each property shown in the present invention.

[0139] <Explanation of terms> In the present invention, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the intention that "it is preferable that it is greater than X" or "it is preferable that it is less than Y." In the present invention, the term "sheet" conceptually encompasses sheets, films, and tapes. [Example]

[0140] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0141] <Preparation of Pressure-Sensitive Adhesive Composition and Pressure-Sensitive Adhesive Sheet> First, the raw materials of the pressure-sensitive adhesive compositions prepared in the examples will be described in detail.

[0142] [(Meth)acrylic polymer (A)] (Meth)acrylic polymer (A-1): An acrylic acid ester copolymer polymer consisting of 67% by mass of 2-ethylhexyl acrylate, 5% by mass of methyl acrylate, 10% by mass of ethyl acrylate, 14% by mass of 2-hydroxyethyl acrylate, and 4% by mass of 4-hydroxybutyl acrylate, and the mass average molecular weight (Mw) of the acrylic acid ester copolymer polymer measured by GPC was 700,000. (Meth)acrylic polymer (A-2): An acrylic acid ester copolymer in which a polymerizable carbon-carbon double bond group was introduced into a side chain by reacting 100 parts by mass of a copolymer obtained by copolymerizing 85% by mass of butyl acrylate and 15% by mass of 2-hydroxyethyl acrylate with 0.06 parts by mass of 2-methacryloyloxyethyl isocyanate in an ethyl acetate solution, and the mass average molecular weight (Mw) of the acrylic acid ester copolymer measured by GPC was 900,000.

[0143] [Hydroxy group-containing benzophenone compound (B)] Hydroxy group-containing benzophenone compound (B-1): 2,2'-dihydroxy-4-methoxybenzophenone (KEMISORB111, manufactured by Chemipro Chemicals Co., Ltd.) Hydroxy group-containing benzophenone compound (B-2): 2,2',4,4'-tetrahydroxybenzophenone (Shipro Chemicals, SEESORB106)

[0144] [Other UV absorbers (B')] UV absorber (B'-1): 2-(5-chloro-2H-benzotriazol-2-yl)-4-methyl-6-tert-butylphenol (BASF, Tinuvin 326)

[0145] [Radical polymerization initiator (C)] Photocleavable radical polymerization initiator (C-1): 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IGM Resins, Omnirad TPO H)

[0146] [Multifunctional (meth)acrylate (D)] Multifunctional (meth)acrylate (D-1): Polypropylene glycol #700 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., APG-700, molecular weight: 823) Multifunctional (meth)acrylate (D-2): Bifunctional urethane acrylate (Mitsubishi Chemical Corporation, Shiko UV-3700B, molecular weight: 38,000)

[0147] [others] Solvent: Ethyl acetate Silane coupling agent: 3-glycidoxypropylmethyldiethoxysilane (Shin-Etsu Silicone, KBM403) Rust inhibitor: 1,2,3-triazole

[0148] <Image display components> The coated polarizing element used in the evaluation as an image display component, and the polymerizable liquid crystal compound and dye contained in the coated polarizing element will be described below.

[0149] (Synthesis of polymerizable liquid crystal compounds) [Liquid crystal compound (I-1)] A liquid crystal compound (I-1) represented by the following formula (I-1) was synthesized according to the description in JP-A-2020-042305.

[0150] TIFF0007739920000001.tif44170

[0151] (Synthesis of pigments) [Dye (II-1)] According to the synthesis method described below, a dye (II-1) represented by the following formula (II-1) was synthesized.

[0152] TIFF0007739920000002.tif94170

[0153] Synthesis of (II-1-a): Tetrahydrofuran (100 mL) and sodium hydride (60% purity, 6.7 g, 168.0 mmol) were added to an ice-cooled reactor, and a mixture of diethyl (4-nitrobenzyl)phosphonate (18.0 g, 65.9 mmol), 4-butylbenzaldehyde (9.1 g, 56.1 mmol), and tetrahydrofuran (50 mL) was added dropwise over 10 minutes. The mixture was washed with tetrahydrofuran (30 mL) and then stirred at 50 °C for 0.5 hours. The reaction mixture was poured into water, extracted with ethyl acetate, washed with water and saturated brine, and the solvent was evaporated. The resulting crude product was dissolved in ethyl acetate (20 mL) with heating, added with hexane (50 mL), and cooled. The precipitate was filtered, washed with hexane, and dried under reduced pressure to obtain 15.0 g of (II-1-a).

[0154] Synthesis of (II-1-b): (II-1-a) (15.0 g, 53.3 mmol), tetrahydrofuran (150 mL), and iron powder (13.9 g, 248.9 mmol) were mixed, and ammonium chloride (13.3 g, 248.6 mmol) dissolved in water (30 mL) was added dropwise, followed by stirring at 50 °C for 3 hours. The mixture was filtered through Celite, extracted with ethyl acetate, washed with water and saturated brine, and the solvent was distilled off. The resulting crude product was suspended in hexane, and the precipitate was filtered off, washed with hexane, and dried to obtain 10.9 g of (II-1-b).

[0155] Synthesis of (II-1): (II-1-b) (2.51 g, 10.0 mmol), N-methylpyrrolidone (40 mL), concentrated hydrochloric acid (2.2 mL), and water (20 mL) were mixed and cooled to 3°C. Then, sodium nitrite (789 mg, 11.4 mmol) was added and the mixture was stirred at 15°C for 3.5 hours. 1-Phenylpyrrolidine (1.47 g, 10.0 mmol), methanol (60 mL), and water (30 mL) were mixed, and the pH was adjusted to 3.5 with concentrated hydrochloric acid. While maintaining the pH at 3 to 5 with aqueous sodium hydroxide, the solution containing the diazonium salt was added dropwise, and the mixture was stirred at 15°C for 3 hours. The resulting precipitate was filtered, washed with water, and dried under reduced pressure. The resulting crude product was purified by silica gel column chromatography (hexane / methylene chloride) to obtain 3.06 g of dye (II-1) as a red solid.

[0156] [Dye (II-2)] According to the synthesis method described below, a dye (II-2) represented by the following formula (II-2) was synthesized.

[0157] TIFF0007739920000003.tif72170

[0158] Synthesis of (II-2): (II-1-b) (1.0 g, 4.0 mmol) and N-methylpyrrolidone (13 mL) were mixed, concentrated hydrochloric acid (1.0 g, 10.0 mmol) was added, and the mixture was cooled in an ice bath. After that, sodium nitrite (0.3 g, 4.4 mmol) dissolved in water (1.3 mL) was added and stirred for 1 hour. The reaction mixture was coupled with 1-phenylpiperidine (0.6 g, 4.0 mmol) dissolved in methanol (25 mL) and water (6.5 mL) at pH = 7. The precipitate was filtered, washed with water, and dried under reduced pressure. The resulting crude product was purified by silica gel column chromatography (hexane / methylene chloride) to yield 760 mg of dye (II-2) as an orange solid.

[0159] The chemical structures of the liquid crystal compounds and dyes synthesized above are shown below. 11 H 22 means that 11 methylene chains are bonded in a linear fashion.

[0160] TIFF0007739920000004.tif41170

[0161] TIFF0007739920000005.tif39170

[0162] TIFF0007739920000006.tif39170

[0163] The chemical structures of dyes (II-3) and (II-4) used in the examples and comparative examples are shown below.

[0164] TIFF0007739920000007.tif43170

[0165] TIFF0007739920000008.tif43170

[0166] (Preparation of Optically Anisotropic Composition) To 69.31 parts of cyclopentanone, 28.57 parts of liquid crystal compound (I-1), 0.10 parts of dye (II-1), 0.43 parts of dye (II-2), 0.39 parts of dye (II-3) (manufactured by Hayashibara Co., Ltd.), 0.90 parts of dye (II-4) (manufactured by Showa Kako Co., Ltd.), 0.23 parts of the following initiator (PI-1), and 0.34 parts of BYK-361N (manufactured by BYK-Chemie) were added, and the mixture was heated and stirred at 80°C, and then filtered using a syringe equipped with a syringe filter (manufactured by Membrane Solutions, PTFE13045, diameter 0.45 μm) to obtain an optically anisotropic composition.

[0167] TIFF0007739920000009.tif54170

[0168] (Manufacturing of coating-type polarizing elements) The optically anisotropic composition prepared above was formed into a film by spin coating on a glass substrate having a polyimide alignment film (LX1400, manufactured by Hitachi Chemical DuPont Microsystems, alignment film formed by rubbing method), and the film was dried by heating at 120°C for 2 minutes, then cooled to the liquid crystal phase, and exposed to an exposure dose of 500 mJ / cm. 2 The film was polymerized at 365 nm to obtain a coating-type polarizing element having a thickness of approximately 3 μm.

[0169] Furthermore, an overcoat layer was formed on the coating-type polarizing element using an overcoat composition by the method described below.

[0170] The curable (meth)acryloyl copolymer (R-1) contained in the overcoat composition was synthesized by the following method. Propylene glycol monomethyl ether (157 parts by mass), glycidyl methacrylate (98 parts by mass), methyl methacrylate (1.0 part by mass), ethyl acrylate (1.0 part by mass), 2,2'-azobis(2,4-dimethylvaleronitrile) (1.0 part by mass), and 1.9 parts by mass of γ-trimethoxysilylpropanethiol (KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to a flask equipped with a thermometer, a stirrer, and a reflux condenser, and the mixture was allowed to react at 65°C for 3 hours. After that, 2,2'-azobis(2,4-dimethylvaleronitrile) (0.5 parts by mass) was further added and reacted for 3 hours, after which propylene glycol monomethyl ether (138 parts by mass) and p-methoxyphenol (0.45 parts by mass) were added and the mixture was heated to 100°C. Next, acrylic acid (51 parts by mass) and triphenylphosphine (3.1 parts by mass) were added and reacted at 110°C for 6 hours to obtain a (meth)acryloyl copolymer (R-1) with a carbon-carbon double bond content (acryloyl equivalent (amount of acryloyl group introduced)) of 4.6 mmol / g and a mass average molecular weight (Mw) of 17,700.

[0171] An overcoat composition was obtained by mixing and stirring 23.08 parts of a 65% solution of curable (meth)acryloyl copolymer (R-1) in propylene glycol monomethyl ether, 0.13 parts of the photopolymerization initiator (PI-2) below, 0.40 parts of BYK-3550 (manufactured by BYK-Chemie), and 76.39 parts of ethanol. This overcoat composition was applied by spin coating to form a film on the coated polarizing element, which was then dried by heating at 50°C for 2 minutes, and then exposed to an exposure dose of 500 mJ / cm 2 (365 nm standard), and then heated at 80° C. for 5 minutes, and an overcoat layer with a thickness of about 5 μm was laminated to obtain a coating-type polarizing element with an overcoat layer. When the obtained coated polarizing element with the overcoat layer was held over a commercially available polarizing plate and rotated, it became bright and dark, and it was confirmed that it exhibited good performance suitable for use as a polarizing film.

[0172] TIFF0007739920000010.tif52170

[0173] [Example 1] Pressure-sensitive adhesive composition 1 was prepared by uniformly mixing 200 parts by mass of a (meth)acrylic polymer (A-1) solution (dilution solvent: ethyl acetate, solids concentration: 50% by mass), 6 parts by mass of a hydroxyl group-containing benzophenone compound (B-1), 3 parts by mass of a photocleavage type radical polymerization initiator (C-1), 25 parts by mass of a multifunctional (meth)acrylate initiator (D-1), 0.3 parts by mass of 3-glycidoxypropylmethyldiethoxysilane (manufactured by Shin-Etsu Silicones, KBM403) as a silane coupling agent, 0.3 parts by mass of 1,2,3-triazole as a rust inhibitor, and 101 parts by mass of ethyl acetate. Pressure-sensitive adhesive composition 1 was spread in a sheet form on a 100 μm thick silicone release-treated release film (Diafoil MRV, manufactured by Mitsubishi Chemical Corporation) so that the thickness after solvent drying would be 50 μm.

[0174] Next, the sheet-shaped PSA composition 1 together with the release film was placed in a dryer heated to 95° C. and held there for 10 minutes to volatilize the solvent contained in the PSA composition 1. Furthermore, a 75 μm-thick release film (Diafoil MRQ manufactured by Mitsubishi Chemical Corporation) that had been subjected to silicone release treatment was laminated on the sheet-shaped pressure-sensitive adhesive composition 1 from which the solvent had been dried to form a laminate, and a high-pressure mercury lamp was used to irradiate the pressure-sensitive adhesive composition 1 through the release film with an integrated irradiation dose of 1000 mJ / cm at a wavelength of 365 nm. 2 , the cumulative irradiation dose at a wavelength of 405 nm is 1400 mJ / cm 2 Thus, a pressure-sensitive adhesive sheet 1 with release film (adhesive sheet thickness: 50 μm) was obtained in which release films were laminated on both the front and back sides.

[0175] [Examples 2 to 3, Comparative Examples 1 to 3] Pressure-sensitive adhesive compositions 2 to 6 and pressure-sensitive adhesive sheets with release films 2 to 6 were prepared in the same manner as in Example 1, except that the types and amounts of the (meth)acrylic polymer (A), hydroxyl group-containing benzophenone compound (B) or other UV absorber (B'), radical polymerization initiator (C), polyfunctional (meth)acrylate (D), and other additives used were as shown in Table 1.

[0176] <Evaluation> The pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets obtained in the examples and comparative examples were measured and evaluated as follows.

[0177] [Light transmittance] The release films on both sides of the adhesive sheets with release films prepared in the Examples and Comparative Examples were sequentially peeled off, and the adhesive sheet (50 μm thick) was sandwiched between two pieces of soda lime glass (0.5 mm thick) and attached. The sheets were then autoclaved (60°C, gauge pressure 0.2 MPa, 20 minutes) and finally attached to prepare samples for evaluating optical properties. The light transmittance of the prepared sample for evaluating optical properties in the wavelength range of 360 to 430 nm was measured using a spectrophotometer (manufactured by Shimadzu Corporation; instrument name "UV2450").

[0178] [b * value] b of the prepared sample for evaluating optical properties * The values ​​were measured in accordance with JIS Z8781-4 using a spectrophotometer (manufactured by Suga Test Instruments Co., Ltd., device name "SC-P").

[0179] [Gel fraction] The gel fraction of the pressure-sensitive adhesive compositions prepared in the course of the Examples and Comparative Examples was measured by the following procedure. 1) The pressure-sensitive adhesive composition is weighed (W1) and wrapped in a pre-weighed SUS mesh (W0). 2) The above SUS mesh is immersed in 100 mL of ethyl acetate for 24 hours. 3) Remove the SUS mesh and dry it at 75°C for 4.5 hours. 4) The mass (W2) after drying is determined, and the gel fraction of the pressure-sensitive adhesive composition is calculated using the following formula. Gel fraction (%) = 100 × (W2 - W0) / W1

[0180] [Adhesive strength] For the pressure-sensitive adhesive sheets with release films prepared in the Examples and Comparative Examples, one release film was peeled off, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd.; product name "Cosmoshine A4300", thickness 100 μm) was roll-pressed onto the backing film using a hand roller. This was cut into 10 mm wide x 100 mm long strips, and the remaining release film was peeled off, and the exposed adhesive surface was roll-bonded to soda-lime glass using a hand roller. The sheets were autoclaved (60°C, gauge pressure 0.2 MPa, 20 minutes) for finish bonding to prepare samples for adhesive strength measurement. Using a universal testing machine (manufactured by INSTRON, model number "5965"), the adhesive sheet was peeled off from the glass while pulling the backing film at an angle of 180° at a peeling rate of 60 mm / min, and the tensile strength was measured with a load cell to determine the 180° peel strength (N / cm) of the adhesive sheet to the glass, which is shown as "Adhesive Strength" in Table 1.

[0181] [Durability] The optical evaluation sample was subjected to a xenon light resistance test using a xenon light resistance tester (manufactured by Atlas Co., Ltd., equipment name "Suntest XPS+") at an illuminance of 60 W / cm. 2 (300-400nm), black panel temperature: 100 hours of UV irradiation conditions, b of the sample after the test * The values ​​were measured in accordance with JIS Z8781-4 using a spectrophotometer (manufactured by Suga Test Instruments Co., Ltd., device name "SC-P").

[0182] The evaluation was based on the following criteria: ○(good): b before and after durability test * The change in value is 3 or less. × (poor): b before and after durability test * The change in value is greater than 3.

[0183] [Protection function of image display device components] For the adhesive sheets with release films prepared in the Examples and Comparative Examples, one release film was peeled off, and the adhesive sheet was roll-pressed onto the overcoat layer of the coating-type polarizing element using a hand roller. The remaining release film was peeled off, and the exposed adhesive surface was roll-attached to soda-lime glass using a hand roller. The sheet was then autoclaved (60°C, gauge pressure 0.2 MPa, 20 minutes) for finish attachment to prepare a sample for measuring the protective function of the coating-type polarizing element. The sample was subjected to a xenon light resistance test using a xenon light resistance tester (manufactured by Atlas, equipment name "Ci4000") at an illuminance of 0.55 W / cm 2 A light resistance test was conducted for 40 hours under ultraviolet light irradiation conditions (340 nm). As the results of the light resistance test, Table 1 shows the change in the degree of polarization at a wavelength of 595 nm before and after the light resistance test (degree of polarization before the test - degree of polarization after the test).

[0184] The degree of polarization (Pe) was calculated by irradiating linearly polarized measurement light onto the anisotropic dye film, measuring the "transmittance of the anisotropic dye film for light polarized in the absorption axis direction" and the "transmittance of the anisotropic dye film for light polarized in the polarization axis direction" using a spectrophotometer (Otsuka Electronics Co., Ltd., product name "RETS-100") equipped with a Glan-Thompson polarizer, and then using the following formula: Pe=(Ty-Tz) / (Ty+Tz) (In the formula, Tz is the transmittance of the anisotropic dye film for light polarized along the absorption axis; Ty is the transmittance of the anisotropic dye film for polarized light in the direction of the polarization axis.

[0185] The evaluation was based on the following criteria: ○ (good): The change in the degree of polarization before and after the light resistance test is 0.25 or less. × (poor): The change in the degree of polarization before and after the light resistance test is greater than 0.25.

[0186] [comprehensive evaluation] In the durability test and the evaluation of the protective function of the components of the image display device, items that were judged as "○ (good)" were judged as "○ (good)", and items that were judged as "× (poor)" in either or both of the durability test and the evaluation of the protective function of the components of the image display device were judged as "× (poor)".

[0187] The results obtained from the measurements and evaluations are shown in Table 1.

[0188] [Table 1]

[0189] From the above examples and the results of tests conducted by the inventors, it is clear that the use of a hydroxyl group-containing benzophenone compound (B) as an ultraviolet absorber provides superior lightfastness reliability compared to Comparative Example 1, which used another ultraviolet absorber (B'). It is also clear that by lowering the transmittance at least at a wavelength of 400 nm, it is possible to prevent the polarization performance of the image display device components from deteriorating over time due to exposure to light. [Explanation of symbols]

[0190] 1. Pressure-sensitive adhesive sheet for image display device components of the present invention 2 Cover glass or cover plastic 3. Optically anisotropic layer (polarizing layer) 4. Orientation film 5. Optically anisotropic layer (retardation layer) 6 Polarizing Plate 7 Retardation plate 8 LCD panel 9. Organic EL panel 10 Resin sheet or glass 11a, 11b Release film 12a to 12c Adhesive layer or pressure-sensitive adhesive layer

Claims

1. the adhesive composition is formed from a (meth)acrylic copolymer (A), a hydroxy group-containing benzophenone compound (B), a radical polymerization initiator (C), and a polyfunctional (meth)acrylate (D), the radical polymerization initiator (C) is a photopolymerization initiator having an absorption maximum at least in the wavelength range of 400 to 430 nm; The light transmittance at a wavelength of 400 nm is less than 30%, A pressure-sensitive adhesive sheet for use as a component of an image display device, which has a transmittance of 80% or more at a wavelength of 430 nm.

2. The pressure-sensitive adhesive sheet for a component of an image display device according to claim 1, which has a transmittance at a wavelength of 380 nm of less than 20%.

3. 3. The pressure-sensitive adhesive sheet for image display device components according to claim 1 or 2, wherein the light transmittance T(380) at a wavelength of 380 nm, the light transmittance T(430) at a wavelength of 430 nm, and the b* value satisfy the relationships of the following formulas (I) and (II): 0≦T(380)×b*≦50 (I) 70≦T(430)×b*≦220 (II)

4. The pressure-sensitive adhesive sheet for image display device components according to any one of claims 1 to 3, wherein the content of the hydroxy group-containing benzophenone compound (B) is 0.1 parts by mass or more per 100 parts by mass of the (meth)acrylic polymer (A).

5. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 4, wherein the (meth)acrylic polymer (A) has a photoactive moiety in a side chain.

6. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 5, wherein the polyfunctional (meth)acrylate (D) is a (meth)acrylate oligomer having a molecular weight of 3,000 or more.

7. 7. The pressure-sensitive adhesive sheet for image display device components according to claim 1, wherein the mass ratio of the hydroxy group-containing benzophenone compound (B) to the radical polymerization initiator (C) is (B):(C)=1:0.05 to 1:

20.

8. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 7, which has a gel fraction of 20% or more and 95% or less.

9. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 8, which has a b* value of 3.0 or less.

10. The pressure-sensitive adhesive sheet for a component of an image display device according to any one of claims 1 to 9, which has a thickness of 10 µm or more and 175 µm or less.

11. The pressure-sensitive adhesive sheet for image display device components according to any one of claims 1 to 10, wherein the image display device components are one of a reflective sheet, a light guide plate and a light source, a diffusion film, a prism sheet, a liquid crystal panel, a retardation plate, a glass substrate, a polarizing plate, an organic EL panel, an electrode, an anti-reflection film, a color filter, a touch sensor, a cover glass, and a cover plastic, or a composite integrated of two or more of these components.

12. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 11, which can be cured in multiple stages.

13. The pressure-sensitive adhesive sheet for components of an image display device according to any one of claims 1 to 12, which has a multi-layer structure of two or more layers.

14. 14. A pressure-sensitive adhesive sheet with a release film, comprising the pressure-sensitive adhesive sheet for a component of an image display device according to claim 1 and a release film laminated together.

15. A pressure-sensitive adhesive sheet with a component of an image display device, comprising the pressure-sensitive adhesive sheet for a component of an image display device according to any one of claims 1 to 13 on a component of an image display device.

16. A resin sheet having one or more resins selected from the group consisting of cycloolefin resins, triacetyl cellulose resins, polymethyl methacrylate resins, epoxy resins, polyester resins and polyimide resins as a main component resin, or a laminated sheet having thin film glass on at least one surface of the adhesive sheet for image display device components according to any one of claims 1 to 13.

17. An image display device comprising the pressure-sensitive adhesive sheet for a component of an image display device according to any one of claims 1 to 13.

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