Pressure-sensitive adhesive sheet, optical laminate, and image display device

Abstract

To provide an adhesive sheet suitable for suppressing breakage of an image display panel due to a local load.SOLUTION: The pressure sensitive adhesive sheet according to the embodiment of the present invention includes a polymer G1 formed from a photocurable composition (I) having a gel-fraction P1 of X (%) after being cured, and a polymer G2 formed from a photocurable composition (II) having a gel-fraction P2 of Y (%) after being cured. The gel fractions G1 and G2 satisfy X <Y.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet, an optical laminate, and an image display device. [Background technology]

[0002] Due to the image formation method used in image display devices (such as liquid crystal display devices, organic EL display devices, and quantum dot display devices), an optical laminate including an optical element such as a polarizing film is often disposed on at least one side of the display cell. Widely known optical elements include anti-reflection layers and anti-glare layers for preventing reflection of external light and glare on the display screen (Patent Document 1). Adhesive sheets are typically used to bond optical elements together or to bond the optical laminate to an image display panel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-155998 Summary of the Invention [Problem to be solved by the invention]

[0004] Lighter weight and greater flexibility are being demanded of image display devices, and in order to meet this demand, measures such as reducing the thickness of the optical components contained in the optical laminate or omitting some of the optical components are being considered. However, when these measures are taken, the image display panel tends to be more susceptible to damage due to the application of a local load (for example, a load caused by contact with a touch pen) to the image display device.

[0005] An object of the present invention is to provide a pressure-sensitive adhesive sheet that is suitable for suppressing damage to an image display panel due to a local load. [Means for solving the problem]

[0006] [1] The pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises: A polymer P1 formed from a photocurable composition (I) having a gel fraction G1 after curing of X (%) and, a polymer P2 formed from a photocurable composition (II) having a gel fraction G2 after curing of Y (%), and, including, the gel fraction G1 and the gel fraction G2 satisfy X < Y. [2] In the adhesive sheet according to [1] above, the gel fraction G1 and the gel fraction G2 may satisfy 0.01 ≦ X / Y < 1.0. [3] In the adhesive sheet according to [1] or [2] above, the gel fraction G1 may satisfy 1.0% ≦ X ≦ 90%. [4] In the adhesive sheet according to any one of [1] to [3] above, the gel fraction G2 may satisfy 60% ≦ Y ≦ 99.9%. [5] In the adhesive sheet according to any one of [1] to [4] above, the photocurable composition (I) may contain a monomer component. [6] In the adhesive sheet according to [5] above, the monomer component may contain at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer. [7] In the adhesive sheet according to [5] or [6] above, the photocurable composition (I) may further contain a crosslinking agent. [8] In the adhesive sheet according to any one of [1] to [7] above, the photocurable composition (II) may contain a polyfunctional (meth)acrylate. [9] In the adhesive sheet according to any one of [1] to [8] above, the photocurable composition (I) and the photocurable composition (II) may not contain an ultraviolet absorber.

[10] The adhesive sheet according to any one of [1] to [9] above may be obtained by adding the photocurable composition (II) to a cured product layer formed from the photocurable composition (I) and curing it.

[11] The method for producing an adhesive sheet according to an embodiment of the present invention is the method for producing an adhesive sheet according to any one of [1] to

[10] above, and, The production method includes the step of adding the photocurable composition (II) to a cured product layer formed from the photocurable composition (I) and curing the composition.

[12] An optical laminate according to an embodiment of the present invention comprises the pressure-sensitive adhesive sheet according to any one of [1] to

[10] above and an optical member.

[13] An image display device according to an embodiment of the present invention includes the optical laminate described in

[12] above. [Effects of the Invention]

[0007] According to an embodiment of the present invention, it is possible to provide a pressure-sensitive adhesive sheet that is suitable for suppressing damage to an image display panel due to a local load. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2A] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet according to the present invention. [Figure 2B] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet according to the present invention. [Figure 2C] 1A to 1C are schematic diagrams illustrating an example of a method for producing a pressure-sensitive adhesive sheet according to the present invention. [Figure 3] 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Figure 4] 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Figure 5] 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Figure 6] 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Figure 7] FIG. 1 is a schematic diagram for explaining a piercing test. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Terminology] In this specification, when the expression "weight" appears, it may be read as "mass," which is the commonly used SI unit for indicating weight, and vice versa.

[0010] In this specification, the expression "(meth)acrylic" means "acrylic and / or methacrylic", the expression "(meth)acrylate" means "acrylate and / or methacrylate", the expression "(meth)allyl" means "allyl and / or methallyl", and the expression "(meth)acrolein" means "acrolein and / or methacrolein".

[0011] In this specification, the term "monomer component" as a criterion for the content of various components in the photocurable composition means the sum of the monomer component that is not partially polymerized and that is contained in the photocurable composition, and the monomer component that is consumed in forming a partially polymerized product that may be contained in the photocurable composition.

[0012] In this specification, with regard to the refractive indices (nx, ny, nz), "nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the in-plane direction perpendicular to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. In this specification, nx, ny, and nz are values ​​for light with a wavelength of 550 nm.

[0013] In this specification, with regard to in-plane retardation (Re), "Re(λ)" is the in-plane retardation of a film measured with light having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation of a film measured with light having a wavelength of 550 nm at 23°C. Re(λ) is calculated by the formula: Re=(nx-ny)×d, where d (nm) is the thickness of the film.

[0014] In this specification, regarding the retardation in the thickness direction (Rth), "Rth(λ)" is the retardation in the thickness direction of the film measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction of the film measured with light of wavelength 550 nm at 23°C. When the thickness of the film is d (nm), Rth(λ) is obtained by the formula: Rth = (nx - nz) × d.

[0015] In this specification, the "Nz coefficient" is obtained by Nz = Rth / Re.

[0016] When referring to an angle in this specification, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

[0017] ≪≪1. Adhesive Sheet≫≫ An example of the adhesive sheet according to an embodiment of the present invention is shown in FIG. 1. The adhesive sheet 10 includes a polymer P1 formed from a photocurable composition (I) having a gel fraction G1 of X (%) after curing, and a polymer P2 formed from a photocurable composition (II) having a gel fraction G2 of Y (%) after curing. The gel fraction G1 and the gel fraction G2 satisfy X < Y.

[0018] The gel fraction G1 can be an index of the crosslinking density of the polymer P1 in the adhesive sheet 10. In other words, the gel fraction G1 can be regarded as the gel fraction of the polymer P1 in the adhesive sheet 10. The gel fraction G1 can be measured by the following method. First, the photocurable composition (I) is sufficiently cured to form a cured product layer. Examples of the curing conditions of the photocurable composition (I) include the conditions described later in the section of ≪1-4. Method for Producing Adhesive Sheet≫. The curing conditions of the photocurable composition (I) are set such that, for example, the total content of the monomer component and the crosslinking agent remaining in the obtained cured product layer is 1000 wtppm or less, preferably 500 wtppm or less.

[0019] Next, a portion of the cured material layer is scraped off to obtain a small piece. The obtained small piece is then wrapped in a stretched porous polytetrafluoroethylene membrane and tied with kite string. This results in a test piece. Next, the total weight (weight A) of the cured material layer piece, the stretched porous membrane, and the kite string is measured. The total weight of the stretched porous membrane and the kite string used is defined as weight B. Next, the test piece is immersed in a container filled with ethyl acetate and left to stand at 23°C for one week. After standing, the test piece is removed from the container and dried in a dryer set to 130°C for two hours, and then the weight C of the test piece is measured. The gel fraction of the cured material layer is calculated from weight A, weight B, and weight C using the following formula. The calculated value can be considered as the gel fraction G1 of the photocurable composition (I) after curing. Gel fraction (wt%) = (CB) / (AB) × 100

[0020] The gel fraction G1 is preferably X≦90%, and may be X≦85%, X≦80%, X≦75%, X≦70%, or even X≦65%. The lower limit of the gel fraction G1 is not particularly limited, and may be, for example, X≧0%, X≧0.1%, X≧1.0%, X≧10%, X≧30%, X≧50%, or even X≧60%. The gel fraction G1 preferably satisfies 1.0%≦X≦90%.

[0021] The gel fraction G2 can be an index of the crosslink density of the polymer P2 in the pressure-sensitive adhesive sheet 10. In other words, the gel fraction G2 can be regarded as the gel fraction of the polymer P2 in the pressure-sensitive adhesive sheet 10. The gel fraction G2 can be measured by the same method as the gel fraction G1, except that the photocurable composition (II) is used instead of the photocurable composition (I). When the photocurable composition (II) contains a solvent, a composition having the same composition as the photocurable composition (II) except that it does not contain the solvent may be separately prepared, and the gel fraction measured using this composition may be regarded as the gel fraction G2. The gel fraction G2 is preferably Y≧60%, and may be Y≧70%, Y≧80%, Y≧90%, Y≧93%, or even Y≧95%. The gel fraction G2 is, for example, Y≦100%, or may be Y≦99.9%. The gel fraction G2 preferably satisfies 60%≦Y≦99.9%.

[0022] The ratio X / Y of the gel fraction G1 to the gel fraction G2 is, for example, X / Y<1.0, and may be X / Y≦0.95, X / Y≦0.90, X / Y≦0.85, X / Y≦0.80, X / Y≦0.75, X / Y≦0.70, or even X / Y≦0.65. The ratio X / Y is, for example, X / Y≧0, and may be X / Y≧0.01, X / Y≧0.10, X / Y≧0.20, X / Y≧0.30, X / Y≧0.40, or even X / Y≧0.50. The gel fractions G1 and G2 preferably satisfy 0.01≦X / Y<1.0.

[0023] ≪1-1. Photocurable composition (I)≫ The photocurable composition (I) is typically a photocurable pressure-sensitive adhesive composition that is cured by irradiation with light. The photocurable composition (I) is cured to form a polymer P1. The photocurable composition is particularly preferred in terms of environmental protection and sustainability, since it can reduce the amount of energy required to form a pressure-sensitive adhesive sheet compared to a thermosetting composition that is cured mainly by heat.

[0024] The photocurable composition (I) preferably contains a monomer component. A part of the monomer component may be a partially polymerized product. The monomer component preferably contains a (meth)acrylic monomer. That is, the photocurable composition (I) preferably contains at least one selected from the group consisting of a (meth)acrylic monomer and a partially polymerized product of the (meth)acrylic monomer.

[0025] The content of the monomer component in the photocurable composition (I) is preferably 50% by weight or more, more preferably 60% by weight or more, even more preferably 70% by weight or more, and particularly preferably 80% by weight or more.

[0026] Examples of (meth)acrylic monomers include (meth)acrylic acid alkyl esters. The (meth)acrylic acid alkyl esters may be of one type only, or of two or more types. The (meth)acrylic acid alkyl esters are typically (meth)acrylic acid alkyl esters in which the alkyl group in the alkyl ester moiety has 1 to 20 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 10, even more preferably 1 to 8, and particularly preferably 2 to 6. The alkyl group may be linear or branched. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of the (meth)acrylic acid alkyl ester include n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and octadecyl (meth)acrylate. Among these, n-butyl (meth)acrylate is preferred as the (meth)acrylic acid alkyl ester, and n-butyl acrylate is more preferred, in terms of being able to further exhibit the effects of the present invention.

[0027] The content of the (meth)acrylic acid alkyl ester in the monomer components is preferably 40 to 100% by weight, more preferably 50 to 99.9% by weight, even more preferably 55 to 99% by weight, and particularly preferably 60 to 99% by weight. This content may be 60 to 95% by weight, 65 to 90% by weight, 68 to 88% by weight, or 70 to 85% by weight.

[0028] The monomer component preferably contains at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer, and more preferably contains both an acidic group-containing monomer and a nitrogen atom-containing monomer.

[0029] The acidic group-containing monomer refers to a monomer having at least one acidic group in its structure. Examples of the acidic group-containing monomer include carboxyl group-containing monomers.

[0030] The carboxyl group-containing monomer may be one type only, or two or more types. The carboxyl group-containing monomer is a compound that contains a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid, with (meth)acrylic acid being preferred and acrylic acid being more preferred.

[0031] Other examples of acidic group-containing monomers include sulfonic acid group-containing monomers such as allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, and sulfopropyl (meth)acrylate; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate.

[0032] The content of the acidic group-containing monomer (particularly the carboxyl group-containing monomer) in the monomer components is preferably 0 to 10% by weight, more preferably 0.1 to 10% by weight, even more preferably 1 to 9% by weight, particularly preferably 2 to 8% by weight, and most preferably 3 to 7% by weight.

[0033] The nitrogen atom-containing monomer refers to a monomer having at least one nitrogen atom in its structure. Examples of the nitrogen atom-containing monomer include amide group-containing monomers.

[0034] The amide group-containing monomer may be one type only or two or more types. The amide group-containing monomer is a compound that contains an amide group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. The amide group-containing monomer is preferably an amide group-containing (meth)acrylate.

[0035] Examples of the amide group-containing monomer include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, and mercaptomethyl(meth)acrylamide. Examples of the monomer include acrylamide monomers such as N-(meth)acrylamide and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. Of these, N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and N-(meth)acryloylmorpholine are preferred, and N-acryloylmorpholine is more preferred.

[0036] Other examples of nitrogen atom-containing monomers include alkylaminoalkyl (meth)acrylates such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide; maleimide-based monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; and itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide.

[0037] The content of the nitrogen atom-containing monomer (particularly the amide group-containing monomer) in the monomer components is, for example, 0% by weight to 50% by weight, or alternatively, 0.1% by weight to 45% by weight, 0.1% by weight to 40% by weight, 0.1% by weight to 35% by weight, 0.1% by weight to 30% by weight, 0.1% by weight to 25% by weight, 1% by weight to 20% by weight, or 5% by weight to 15% by weight.

[0038] The monomer component may contain an aromatic ring-containing monomer. The aromatic ring-containing monomer is a compound that contains an aromatic ring in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. The aromatic ring-containing monomer is suitable for improving the heat resistance of the photocurable composition.

[0039] Examples of aromatic rings include carbon rings such as a benzene ring (which may be a benzene ring constituting a part of a biphenyl structure or a fluorene structure), a naphthalene ring, an anthracene ring, and a phenanthrene ring.

[0040] The aromatic ring-containing monomer may be one kind only or two or more kinds. Examples of the aromatic ring-containing monomer include (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, (meth)acrylic acid aryloxyalkyl esters such as phenoxyethyl (meth)acrylate, and (meth)acrylic acid arylalkyl esters such as benzyl (meth)acrylate, and are preferably phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and the like, and more preferably benzyl (meth)acrylate.

[0041] The content of the aromatic ring-containing monomer in the monomer components is, for example, 0% by weight to 50% by weight, or may be 0.1% by weight to 40% by weight, 1% by weight to 30% by weight, 5% by weight to 25% by weight, or 10% by weight to 25% by weight.

[0042] The monomer component may or may not contain a hydroxy group-containing monomer. The hydroxy group-containing monomer may be one type only, or two or more types. Examples of the hydroxy group-containing monomer include hydroxy group-containing (meth)acrylates having 1 to 20 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. The content of the hydroxy group-containing monomer in the monomer component is preferably 0 to 20% by weight. This content may be 0 to 15% by weight, 0 to 10% by weight, 0 to 7% by weight, or 0 to 5% by weight.

[0043] The monomer component may contain an ether group-containing monomer. The ether group-containing monomer may be of only one type or of two or more types. Examples of the ether group-containing monomer include alkoxy group-containing monomers. Examples of the alkoxy group-containing monomer include alkylene oxide adducts represented by the following chemical formula (1). In chemical formula (1), R 1 is a hydrogen atom or a methyl group, and R 2 is an alkyl group. 2 R may be linear or branched, and is preferably linear. 2 Specific examples of n are typically a methyl group and an ethyl group. In chemical formula (1), n ​​is an integer of 1 to 30, preferably an integer of 1 to 12, and more preferably an integer of 1 to 5. [ka]

[0044] Specific examples of the alkylene oxide adduct represented by chemical formula (1) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate.

[0045] The ether group-containing monomer is not limited to the alkylene oxide adduct. The ether group-containing monomer may have a ring structure, and the ring structure may have an ether group. Examples of the ring structure having an ether group include a tetrahydrofuran ring and a dioxane ring. Specific examples of the ether group-containing monomer having a ring structure include cyclic trimethylolpropane formal (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

[0046] The content of the ether group-containing monomer in the monomer components is, for example, 0 to 20% by weight, and may be 0 to 15% by weight, 0 to 10% by weight, 0 to 7% by weight, or 0 to 5% by weight.

[0047] The monomer component may contain other copolymerizable monomers. The other copolymerizable monomers may be of only one type, or of two or more types. Examples of other copolymerizable monomers include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; vinyl-based monomers such as vinyl acetate and vinyl propionate; cyanoacrylate-based monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate; glycol-based (meth)acrylates such as carbitol (meth)acrylate, ethyl carbitol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; Examples of the monomer include (meth)acrylates such as trihydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, and silicone (meth)acrylate; and silane monomers containing silicon atoms such as 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0048] The content of other copolymerizable monomers in the monomer components is, for example, 0% by weight to 20% by weight, or may be 0% by weight to 15% by weight, or 0% by weight to 10% by weight, or 0% by weight to 5% by weight, or 0% by weight to 3% by weight.

[0049] The photocurable composition (I) may contain a partial polymer of the above-mentioned monomer components. The partial polymer may be either a homopolymer or a copolymer. The partial polymer can appropriately increase the viscosity of the photocurable composition (I), thereby contributing to the stable formation of a coating layer, which will be described later.

[0050] The photocurable composition (I) may contain a photopolymerization initiator. Any appropriate photopolymerization initiator may be used as long as it does not impair the effects of the present invention. Examples of the photopolymerization initiator include photoradical generators that generate radicals when exposed to visible light and / or ultraviolet light having a wavelength shorter than 450 nm. The photopolymerization initiator may be one type only, or two or more types.

[0051] Examples of photopolymerization initiators include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzil dimethyl ketal. aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates.

[0052] The photopolymerization initiator may be one having two or more (preferably 2 to 5) photodegradable groups. The photodegradable group refers to a functional group that absorbs irradiated active energy rays and generates radicals, and specific examples thereof include a ketone group, a halogenated alkyl group, an ester group, a sulfone group, and a peroxy group.

[0053] Examples of the photopolymerization initiator having two or more photodegradable groups include 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methylpropan-1-one (commercially available products include, for example, the trade name "Omnirad127D" manufactured by IGM Resins BV), 1-[4-(4-benzoxylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one (commercially available products include, for example, the trade name "ESACURE 1001M" manufactured by IGM Resins BV), methyl benzoyl formate (commercially available products include, for example, the trade name "SPEEDCURE MBF" manufactured by ARKEMA Sartomer), and O-ethoxyimino-1-phenylpropan-1-one (commercially available products include, for example, the trade name "SPEEDCURE PDO" manufactured by ARKEMA Sartomer). Examples of suitable hydroxybenzoates include oligo[2-hydroxy-2-methyl-4-(1-methylvinyl)phenyl]propanone (manufactured by Sartomer) and oligo[2-hydroxy-2-methyl-4-(1-methylvinyl)phenyl]propanone (a commercially available product is, for example, the trade name "ESACURE KIP150" manufactured by IGM Resins BV).

[0054] As the photopolymerization initiator, a compound containing a phosphorus atom and / or a nitrogen atom may be used. Examples of such photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (commercially available products include, for example, the trade name "Omnirad907" manufactured by IGM Resins BV), 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (commercially available products include, for example, the trade name "Omnirad369" manufactured by IGM Resins BV), 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one (commercially available products include, for example, the trade name "Omnirad379" manufactured by IGM Resins BV), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (commercially available products include, for example, the trade name "Omnirad819" manufactured by IGM Resins BV). Examples of commercially available products include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (a commercially available product is, for example, under the trade name "OmniradTPO", manufactured by IGM Resins BV), 1,2-octanedione-1-[4-(phenylthio)phenyl-2-(O-benzoyloxime)] (a commercially available product is, for example, under the trade name "OmniradOXE01", manufactured by IGM Resins BV), and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime) (a commercially available product is, for example, under the trade name "OmniradOXE02", manufactured by IGM Resins BV).

[0055] The content of the photopolymerization initiator in the photocurable composition (I) may be any appropriate content within the range that does not impair the effects of the present invention. The content of such a photopolymerization initiator may be, for example, 0.02 to 10 parts by weight, 0.05 to 5 parts by weight, or even 0.1 to 1 part by weight, relative to 100 parts by weight of the monomer components.

[0056] The photocurable composition (I) may or may not contain a crosslinking agent. The crosslinking agent may be of one kind or of two or more kinds.

[0057] Examples of crosslinking agents include polyfunctional (meth)acrylates (such as ester compounds of polyhydric alcohols and (meth)acrylic acid), allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy (meth)acrylate, polyester (meth)acrylate, urethane (meth)acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate.

[0058] Examples of the polyfunctional (meth)acrylate include difunctional (meth)acrylate, trifunctional (meth)acrylate, and polyfunctional (meth)acrylate having tetrafunctional or more.

[0059] Examples of bifunctional (meth)acrylates include (poly)ethylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; (poly)propylene glycol di(meth)acrylates such as propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and tetrapropylene glycol di(meth)acrylate; Examples of suitable di(meth)acrylates include butyl glycol di(meth)acrylate; pentaerythritol di(meth)acrylate; 1,2-ethylene glycol di(meth)acrylate; 1,6-hexanediol di(meth)acrylate; 1,9-nonanediol diacrylate (NDDA); 1,12-dodecanediol di(meth)acrylate; glycerin di(meth)acrylate; stearic acid-modified pentaerythritol di(meth)acrylate; dicyclopentadienyl di(meth)acrylate; di(meth)acryloyl isocyanurate; and ethoxylated bisphenol A di(meth)acrylate.

[0060] Examples of trifunctional (meth)acrylates include pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tris((meth)acryloyloxyethyl)isocyanurate.

[0061] Examples of tetrafunctional or higher polyfunctional (meth)acrylates include di(trimethylolpropane)tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol penta(meth)acrylate.

[0062] One preferred embodiment of the polyfunctional (meth)acrylate is 1,9-nonanediol di(meth)acrylate (e.g., 1,9-nonanediol diacrylate (NDDA)) or di(trimethylolpropane)tetra(meth)acrylate. As the di(trimethylolpropane)tetra(meth)acrylate, for example, a commercially available product under the trade name "PHOTOMER 4306" (manufactured by IGM Resins BV) can be used.

[0063] As the epoxy (meth)acrylate, a commercially available product such as "EBECRYL3700" (manufactured by Daicel Allnex Co., Ltd.) can be used.

[0064] As the polyester (meth)acrylate, a commercially available product such as "PHOTOMER5429" (manufactured by IGM Resins BV) can be used.

[0065] As the urethane (meth)acrylate, a commercially available product such as "EBECRYL4859" (manufactured by Daicel Allnex Co., Ltd.) can be used.

[0066] A polyfunctional oligomer may be used as the crosslinking agent. Only one type of polyfunctional oligomer may be used, or two or more types may be used. Examples of polyfunctional oligomers include urethane (meth)acrylate oligomers (oligomers having a urethane skeleton and two or more (meth)acryloyl groups), epoxy (meth)acrylate oligomers (oligomers having an epoxy skeleton and two or more (meth)acryloyl groups), and silicone (meth)acrylate oligomers (oligomers having a siloxane skeleton and two or more (meth)acryloyl groups). A preferred example of the polyfunctional oligomer is a urethane (meth)acrylate oligomer. Commercially available urethane (meth)acrylate oligomers include, for example, products manufactured by Negami Chemical Industrial Co., Ltd. under the trade names "Art Resin PMH-401B," "Art Resin UN-333," "Art Resin UN-350," "Art Resin UN-353," "Art Resin UN-5500," and "Art Resin UN-5590."

[0067] The weight-average molecular weight (Mw) of the polyfunctional oligomer is, for example, 1,000 to 50,000, or may be 5,000 to 40,000, 8,000 to 30,000, 11,000 to 25,000, 14,000 to 23,000, or 16,000 to 22,000. Such a configuration is preferable from the viewpoint of appropriately adjusting the viscoelasticity (e.g., shear storage modulus and loss tangent) of the polymer P1. The weight-average molecular weight (Mw) herein is a value (polystyrene equivalent) based on measurements by GPC (gel permeation chromatography).

[0068] In order to further exert the effects of the present invention, it is preferable to select at least one crosslinking agent selected from the group consisting of polyfunctional (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates, urethane (meth)acrylates, and polyfunctional oligomers.

[0069] As the crosslinking agent, an isocyanate-based crosslinking agent may be used in combination with the above crosslinking agent. Such an isocyanate-based crosslinking agent may be used alone or in combination of two or more. The content of the isocyanate-based crosslinking agent in the total amount of crosslinking agents is preferably 0% by weight to 50% by weight, more preferably 0% by weight to 30% by weight, even more preferably 0% by weight to 10% by weight, particularly preferably 0% by weight to 5% by weight, and most preferably 0% by weight to 1% by weight.

[0070] As the isocyanate crosslinking agent, any suitable conventionally known isocyanate crosslinking agent can be used. As the isocyanate crosslinking agent, a compound having at least two isocyanate groups (isocyanate compound) can be used. The number of isocyanate groups contained in the isocyanate compound is preferably 3 or more. The upper limit of the number of isocyanate groups is not particularly limited, and is, for example, 5. Examples of the isocyanate compound include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0071] Examples of aromatic isocyanate compounds include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and xylylene diisocyanate.

[0072] Examples of alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0073] Examples of the aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0074] Examples of the isocyanate-based crosslinking agent include polymers (dimers, trimers, pentamers, etc.) of the above-mentioned isocyanate compounds, adducts obtained by adding them to polyhydric alcohols such as trimethylolpropane, urea-modified products, biuret-modified products, allophanate-modified products, isocyanurate-modified products, carbodiimide-modified products, and urethane prepolymers obtained by adding them to polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.

[0075] The isocyanate-based crosslinking agent may contain at least one derivative selected from an alicyclic isocyanate compound and an aliphatic isocyanate compound. It is particularly preferred that the isocyanate-based crosslinking agent be at least one selected from the group consisting of pentamethylene diisocyanate (PDI)-based crosslinking agents (PDI and its derivatives) and hexamethylene diisocyanate (HDI)-based crosslinking agents (HDI and its derivatives). Specific examples of PDI-based crosslinking agents include isocyanurate-modified PDI. Specific examples of HDI-based crosslinking agents include isocyanurate-modified and biuret-modified HDI.

[0076] The content of the crosslinking agent in the photocurable composition (I) may be appropriately set depending on the molecular weight, the number of functional groups, etc. In order to further demonstrate the effects of the present invention, the content of the crosslinking agent (particularly the polyfunctional (meth)acrylate) per 100 parts by weight of the monomer components is preferably 0 to 20 parts by weight. This content may be 0.01 to 10 parts by weight, 0.01 to 7 parts by weight, 0.01 to 5 parts by weight, 0.05 to 3 parts by weight, 0.05 to 1 part by weight, or 0.05 to 0.5 parts by weight.

[0077] The photocurable composition (I) may contain any other appropriate additives as long as the effects of the present invention are not impaired. The other additives may be one type only or two or more types. Examples of such other additives include chain transfer agents, silane coupling agents, viscosity modifiers, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, rust inhibitors, antioxidants, antistatic agents, UV absorbers, and solvents.

[0078] In one embodiment of the photocurable composition (I), the content of the ultraviolet absorber in the photocurable composition (I) relative to 100 parts by weight of the monomer component is preferably 0 to 5 parts by weight, may be 0 to 3 parts by weight, may be 0 to 2 parts by weight, may be 0 to 1 part by weight, or may be substantially 0 part by weight.

[0079] The photocurable composition (I) may contain a solvent, and the content of the solvent in the photocurable composition (I) is preferably 5% by weight or less.

[0080] The viscosity of the photocurable composition (I) is, for example, 5 to 150 poise.

[0081] ≪1-2. Photocurable composition (II)≫ The photocurable composition (II) is a photocurable composition that is cured by irradiation with light. When the photocurable composition (II) is cured, a polymer P2 is formed.

[0082] The photocurable composition (II) preferably contains at least one selected from the group consisting of a monomer component and a crosslinking agent. The monomer component and the crosslinking agent described in Section 1-1. Photocurable composition (I) may be used. The photocurable composition (II) preferably contains only the crosslinking agent among the monomer component and the crosslinking agent. In this embodiment, the crosslinking agent can function as a photopolymerizable compound.

[0083] When the photocurable composition (II) contains a monomer component, the monomer component may be one kind or two or more kinds, and the photocurable composition (II) may contain a partial polymer of the monomer component.

[0084] The monomer component preferably contains a nitrogen atom-containing monomer (particularly an amide group-containing monomer). In the photocurable composition (II), the monomer component may contain a monomer other than the monomers described in Section 1-1. Photocurable composition (I). Examples of the other monomer include a monomer having a cyclic structure in the molecule.

[0085] Examples of monomers having a cyclic structure in the molecule include (meth)acrylic acid cycloalkyl esters such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, and 1-adamantyl (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings such as (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate; (meth)acrylic acid esters having an aromatic ring such as (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, (meth)acrylic acid aryloxyalkyl esters such as phenoxyethyl (meth)acrylate, and (meth)acrylic acid arylalkyl esters such as benzyl (meth)acrylate.

[0086] The content of the monomer component in the photocurable composition (II) (particularly, the content of the monomer component in the total solid content excluding the solvent) is, for example, 90% by weight or less, and may be 75% by weight or less, 50% by weight or less, 30% by weight or less, 10% by weight or less, 5% by weight or less, or even 1% by weight or less. The photocurable composition (II) may not contain a monomer component.

[0087] When the photocurable composition (II) contains a crosslinking agent, the crosslinking agent may be one kind or two or more kinds. The crosslinking agent preferably contains a polyfunctional (meth)acrylate (particularly a bifunctional (meth)acrylate).

[0088] The content of the crosslinking agent in the photocurable composition (II) (particularly, the content of the crosslinking agent in the total solid content excluding the solvent) is, for example, 10% by weight or more, and may be 25% by weight or more, 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or even 95% by weight or more. The upper limit of this content is not particularly limited, and is, for example, 99% by weight or less.

[0089] The photocurable composition (II) may contain a photopolymerization initiator. The photopolymerization initiators described in the section 1-1. Photocurable composition (I) may be used. The photopolymerization initiator may be one type or two or more types.

[0090] The content of the photopolymerization initiator in the photocurable composition (II) may be any appropriate content within the range that does not impair the effects of the present invention. The content of such a photopolymerization initiator is, for example, 0.02 to 10 parts by weight, preferably 0.05 to 5 parts by weight, relative to 100 parts by weight of the total of the monomer components and the crosslinking agent.

[0091] The photocurable composition (II) may contain any other appropriate additives as long as the effects of the present invention are not impaired. Examples of the other additives include those described in Section 1-1. Photocurable composition (I). The other additives may be one type or two or more types.

[0092] In one embodiment of the photocurable composition (II), the content of the ultraviolet absorber relative to 100 parts by weight of the total of the monomer components and the crosslinking agent is preferably 0 to 5 parts by weight, may be 0 to 3 parts by weight, may be 0 to 2 parts by weight, may be 0 to 1 part by weight, or may be substantially 0 part by weight. In particular, it is preferable that the photocurable composition (I) and the photocurable composition (II) do not contain an ultraviolet absorber.

[0093] The photocurable composition (II) may contain a solvent. The solvent may be one type or two or more types. Examples of the solvent include esters such as methyl acetate, ethyl acetate, isopropyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; aliphatic hydrocarbons such as hexane, heptane, and octane; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as chloroform, dichloromethane, and 1,2-dichloroethane; ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; nitriles such as acetonitrile, propionitrile, and benzonitrile; and alcohols such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, and tert-butanol.

[0094] The amount of the solvent may be any appropriate amount within a range that does not impair the effects of the present invention.

[0095] The total amount of the photocurable composition (II) (particularly, the total solid content excluding the solvent) relative to 100 parts by weight of the total amount of the photocurable composition (I) is, for example, 1 part by weight to 100 parts by weight, or alternatively, 3 parts by weight to 70 parts by weight, 5 parts by weight to 50 parts by weight, 7 parts by weight to 40 parts by weight, or 10 parts by weight to 30 parts by weight.

[0096] The viscosity of the photocurable composition (II) is, for example, 0.01 to 150 poise.

[0097] 1-3. Polymers P1 and P2 As described above, the pressure-sensitive adhesive sheet 10 includes a polymer P1 formed from the photocurable composition (I) and a polymer P2 formed from the photocurable composition (II). Specifically, the polymer P1 includes structural units derived from the monomer components and crosslinking agent contained in the photocurable composition (I). The polymer P2 includes structural units derived from the monomer components and crosslinking agent contained in the photocurable composition (II).

[0098] In the pressure-sensitive adhesive sheet 10, the polymers P1 and P2 preferably exist independently of each other and may form an interpenetrating polymer network (IPN) structure or a semi-interpenetrating network (semi-IPN) structure. The interpenetrating network structure is also sometimes called a double network structure.

[0099] 1-4. Manufacturing method of adhesive sheet The pressure-sensitive adhesive sheet 10 can be produced, for example, by the following method. First, as shown in FIG. 2A , a laminate is produced that includes, in this order, a base sheet 20, a coating layer 11 containing a photocurable composition (I), and a release liner 21. This laminate can be formed, for example, by forming the coating layer 11 on the base sheet 20 (or release liner 21), and then placing the release liner 21 (or base sheet 20) on the formed coating layer 11. Alternatively, the laminate may be formed by applying the photocurable composition (I) in a poured manner into the space between the base sheet 20 and the release liner 21, which are held at a predetermined distance so that their main surfaces face each other. After forming the coating layer 11, heating and drying may be performed, if necessary.

[0100] The coating layer 11 can be formed by various coating methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0101] The thickness of coating layer 11 can be adjusted depending on the desired thickness of pressure-sensitive adhesive sheet 10, and may be, for example, 500 μm or less, 250 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of coating layer 11 may be, for example, 5 μm or more, 10 μm or more, or even 50 μm or more.

[0102] The base sheet 20 may be in the form of a sheet or a continuous piece. The base sheet 20 may be, for example, a resin film. Examples of resins constituting the resin film include polyesters such as polyethylene terephthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin constituting the resin film is preferably polyester, such as polyethylene terephthalate.

[0103] Any appropriate thickness can be adopted as the thickness of the base sheet 20 as long as it does not impair the effects of the present invention. Such a thickness is, for example, 10 μm to 200 μm, and preferably 25 μm to 150 μm.

[0104] The substrate sheet 20 may have a release layer on the surface on the coating layer 11 side. Any appropriate release layer may be used as the release layer as long as the effects of the present invention are not impaired. For example, a commonly known release layer may be used as such a release layer. A typical example of such a release layer is a cured layer of a release agent composition containing a release agent. Examples of the release agent include silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder. Any appropriate thickness may be used as the release layer as long as the effects of the present invention are not impaired. Examples of such a thickness are 10 nm to 300 nm.

[0105] The substrate of the release liner 21 (hereinafter referred to as "liner substrate") can be, for example, a resin film. Examples of resins that can be used to form the resin film include polyesters such as polyethylene terephthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. A preferred resin for forming the resin film is polyester, such as polyethylene terephthalate. The thickness of the release liner 21 is, for example, 10 μm to 200 μm.

[0106] The release liner 21 may include a layer other than the liner substrate. The release liner 21 may include a release layer. For example, the release liner 21 includes a liner substrate and a release layer formed on one surface of the liner substrate. The release layer of the release liner 21 may be on the coating layer 11 side.

[0107] Next, the laminate is irradiated with light L1. The coating layer 11 is irradiated with light L1 and cured to form a cured product layer 12 (FIG. 2B). Irradiation with light L1 is typically carried out from the side of the base sheet 20. In this case, light L1 passes through the base sheet 20 and reaches the coating layer 11, curing the coating layer 11. However, irradiation with light L1 may also be carried out from the side of the release liner 21, or from both the side of the release liner 21 and the side of the base sheet 20.

[0108] The light L1 to be irradiated may be any appropriate light under any appropriate conditions as long as the effects of the present invention are not impaired. The light L1 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light source of the light L1 may be, for example, a light irradiation device equipped with an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps include ultraviolet LEDs, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, microwave-excited mercury lamps, black light lamps, chemical lamps, germicidal lamps, low-pressure discharge mercury lamps, and excimer lasers, and two or more ultraviolet irradiation lamps may be combined. The illuminance of the irradiated light L1 is, for example, 1 mW / cm 2 ~20mW / cm 2 The irradiation time of the irradiated light L1 is, for example, 5 minutes to 5 hours. The integrated light amount of the irradiated light L1 is, for example, 100 mJ / cm 2 2 ~5000mJ / cm 2 is.

[0109] The irradiation conditions of the light L1 are not limited to those described above. For example, when a gallium-filled metal halide lamp or an LED emitting light with a wavelength of 405 nm is used as the light source of the light L1, the illuminance of the light L1 is 100 mW / cm 2 ~2000mW / cm 2 The irradiation time of the light L1 may be 1 to 2 seconds.

[0110] The cured material layer 12 contains a polymer P1 formed from the photocurable composition (I). The total content of the monomer component derived from the photocurable composition (I) and the crosslinking agent remaining in the cured material layer 12 is, for example, 1000 wtppm or less, and may be 500 wtppm or less, or even 100 wtppm or less. It is preferable that the cured material layer 12 is substantially free of the monomer component derived from the photocurable composition (I) or the crosslinking agent.

[0111] Next, as shown in FIG. 2B, the release liner 21 is peeled off from the laminate to expose the surface of the cured material layer 12. A photocurable composition (II) is applied to the exposed surface of the cured material layer 12. At this time, the applied photocurable composition (II) permeates into the cured material layer 12. This results in a precursor layer 13 of the pressure-sensitive adhesive sheet 10 (FIG. 2C). Within the precursor layer 13, monomer components and crosslinking agents derived from the photocurable composition (II) are dispersed. In the manufacturing method of this embodiment, the photocurable composition (II) can be considered an additive added to the cured material layer 12.

[0112] Next, if necessary, the cured product layer 12 (precursor layer 13) coated with the photocurable composition (II) is dried. The precursor layer 13 may be dried under any appropriate conditions as long as the effects of the present invention are not impaired. The drying temperature of the precursor layer 13 is, for example, 30°C to 200°C. The drying time of the precursor layer 13 is, for example, 1 minute to 1 hour.

[0113] 2C, a release liner 22 is attached to the exposed surface of the precursor layer 13. This results in a laminate comprising, in this order, the base sheet 20, the precursor layer 13, and the release liner 22. As the release liner 22, the same ones as those described above for the release liner 21 can be used, and the release liner 21 itself may also be reused.

[0114] Next, the obtained laminate is irradiated with light L2. The precursor layer 13 is irradiated with light L2 and cured to become the pressure-sensitive adhesive sheet 10. In detail, when the precursor layer 13 is irradiated with light L2, the monomer component and crosslinking agent derived from the photocurable composition (II) react within the precursor layer 13 to form a polymer P2. Irradiation with light L2 is typically carried out from the side of the base sheet 20. At this time, light L2 passes through the base sheet 20 and reaches the precursor layer 13. However, irradiation with light L2 may also be carried out from the side of the release liner 22, or from both the side of the release liner 22 and the side of the base sheet 20. Irradiation conditions for light L2 include those described above for light L1.

[0115] As described above, the pressure-sensitive adhesive sheet 10 of this embodiment can be obtained, for example, by adding the photocurable composition (II) to the cured material layer 12 formed from the photocurable composition (I) and curing the resulting material. In other words, the method for producing the pressure-sensitive adhesive sheet 10 of this embodiment includes, for example, a step of adding the photocurable composition (II) to the cured material layer 12 formed from the photocurable composition (I) and curing the resulting material. However, the method for producing the pressure-sensitive adhesive sheet 10 is not limited to the above. For example, the pressure-sensitive adhesive sheet 10 may be produced by adding the photocurable composition (I) to a cured material layer formed by first curing the photocurable composition (II) and then curing the resulting material.

[0116] Furthermore, an optical member (for example, the first optical member 30 described below) may be used in place of the release liner 22 used in FIG. 2C. In this case, an optical laminate including the pressure-sensitive adhesive sheet 10 and the optical member can be easily produced by irradiating light L2 onto a laminate including the base sheet 20, precursor layer 13, and optical member in this order. This manufacturing method improves the anchoring strength of the pressure-sensitive adhesive sheet 10 and the optical member, and can improve reliability in high-temperature environments. Similarly, an optical member (for example, the polarizing film 40, second optical member 31, or a laminate of the second optical member 31 and third optical member 32 described below) may be used in place of the base sheet 20 used in FIGS. 2A to 2C.

[0117] ≪1-5. Physical properties of adhesive sheets≫ The gel fraction of the pressure-sensitive adhesive sheet 10 is, for example, 50% or more, and may be 75% or more, 80% or more, 85% or more, or even 90% or more.

[0118] The thickness of the pressure-sensitive adhesive sheet 10 is, for example, 500 μm or less, and may be 250 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of the pressure-sensitive adhesive sheet 10 is, for example, 1 μm or more, and may be 5 μm or more, 10 μm or more, or even 50 μm or more.

[0119] The Young's modulus of the pressure-sensitive adhesive sheet 10 is, for example, 0.2 MPa or more, and may be 0.3 MPa or more, 0.4 MPa or more, 0.6 MPa or more, 0.8 MPa or more, 1.0 MPa or more, 1.2 MPa or more, 1.5 MPa or more, 2.0 MPa or more, 5.0 MPa or more, 10 MPa or more, 15 MPa or more, or even 20 MPa or more. The upper limit of the Young's modulus of the pressure-sensitive adhesive sheet 10 is, for example, 2 GPa or less, and may be 1 GPa or less, 100 MPa or less, or even 50 MPa or less. The Young's modulus of the pressure-sensitive adhesive sheet 10 can be calculated from the stress-strain curve measured when a string-shaped sample of the pressure-sensitive adhesive sheet 10 is prepared and pulled at a rate of 50 mm / min using a tensile tester.

[0120] ≪≪2. Optical laminate≫≫ An optical laminate according to an embodiment of the present invention includes, for example, the above-described pressure-sensitive adhesive sheet 10 and an optical member. The optical laminate is used by being attached to, for example, an image display panel. The optical laminate may be disposed on the viewing side of the image display panel, or on the light source side (opposite the viewing side) of the image display panel.

[0121] 2-1. Overall structure of optical laminate Fig. 3 is a schematic cross-sectional view of a representative optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in Fig. 3 includes a first optical member 30 and a first adhesive sheet 10A. The optical laminate 100 can be attached to an image display panel by the first adhesive sheet 10A.

[0122] Fig. 4 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 110 shown in Fig. 4 includes a first optical member 30, a first adhesive sheet 10A, a second optical member 31, and a second adhesive sheet 10B, in this order. In the optical laminate 110, the first optical member 30 and the second optical member 31 are bonded together via the first adhesive sheet 10A. The optical laminate 110 can be attached to an image display panel by the second adhesive sheet 10B.

[0123] FIG. 5 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 120 shown in FIG. 5 includes, in this order, a first optical member 30, a first adhesive sheet 10A, a second optical member 31, a second adhesive sheet 10B, a third optical member 32, and a third adhesive sheet 10C. In the optical laminate 120, the first optical member 30 and the second optical member 31 are bonded together via the first adhesive sheet 10A. The second optical member 31 and the third optical member 32 are bonded together via the second adhesive sheet 10B. The optical laminate 120 can be attached to an image display panel via the third adhesive sheet 10C. Note that, in the optical laminate 120, any appropriate adhesive layer may be used instead of the second adhesive sheet 10B.

[0124] FIG. 6 is a schematic cross-sectional view of another representative optical laminate according to an embodiment of the present invention. The optical laminate 130 shown in FIG. 6 includes a first optical member 30, a first adhesive sheet 10A, and a polarizing film 40, in this order. The first optical member 30 and the polarizing film 40 are bonded together via the first adhesive sheet 10A. The optical laminate 130 may further include, in this order from the polarizing film 40 side, a first retardation film 50 and a second retardation film 60 on the opposite side of the first optical member 30 with respect to the polarizing film 40. The optical laminate 130 may further include a fourth adhesive sheet 10D arranged on the opposite side of the second retardation film 60 from the first retardation film 50. The optical laminate 130 can be attached to an image display panel by the fourth adhesive sheet 10D. 6 includes, in this order, a first optical member 30, a first adhesive sheet 10A, a polarizing film 40, a first retardation film 50, a second retardation film 60, and a fourth adhesive sheet 10D. For convenience, the polarizing film and the retardation film are described herein as being distinct from the first optical member, but these are also types of optical members.

[0125] In the optical laminate 130, the configurations of the first optical member 30 and the first adhesive sheet 10A are the same as those of the optical laminate 100 in Fig. 3. Instead of the above configuration (configuration of first optical member 30 / first adhesive sheet 10A), the optical laminate 130 may have the configuration of the optical laminate 110 in Fig. 4 (configuration of first optical member 30 / first adhesive sheet 10A / second optical member 31 / second adhesive sheet 10B), or may have the configuration of the optical laminate 120 in Fig. 5 (configuration of first optical member 30 / first adhesive sheet 10A / second optical member 31 / second adhesive sheet 10B / third optical member 32 / third adhesive sheet 10C).

[0126] The optical laminate according to an embodiment of the present invention may have any appropriate configuration as long as it includes an optical member and the pressure-sensitive adhesive sheet 10 described in the section <<1. Pressure-sensitive adhesive sheet>>. Representative configurations include those shown in FIGS. 3 to 6, with the configuration shown in FIG. 3 being particularly preferred. The configuration shown in FIG. 3 (the configuration of first optical member 30 / first pressure-sensitive adhesive sheet 10A) allows for fewer components, which can be advantageous from the standpoints of cost and the environment. For example, the configuration shown in FIG. 3 is preferred because it requires fewer lamination steps for the optical laminate.

[0127] The total thickness of the optical laminate according to the embodiment of the present invention is preferably 50 μm or more, more preferably 100 μm to 500 μm, still more preferably 150 μm to 400 μm, and particularly preferably 150 μm to 300 μm.

[0128] The components of the optical laminate will be described below.

[0129] ≪2-2. First adhesive sheet≫ The first adhesive sheet is preferably the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>. The thickness of the first adhesive sheet is preferably 5 μm to 200 μm, more preferably 5 μm to 170 μm, even more preferably 5 μm to 150 μm, particularly preferably 5 μm to 130 μm, and most preferably 5 μm to 110 μm. In some cases, the thickness of the first adhesive sheet may be 5 μm to 20 μm, 5 μm to 17 μm, 5 μm to 16 μm, 5 μm to 15 μm, or even 5 μm to 14 μm.

[0130] ≪2-3. Second adhesive sheet≫ Any suitable adhesive sheet can be used as the second adhesive sheet as long as it does not impair the effects of the present invention. The second adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0131] The thickness of the second pressure-sensitive adhesive sheet is preferably 5 μm to 20 μm, more preferably 5 μm to 17 μm, even more preferably 5 μm to 16 μm, particularly preferably 5 μm to 15 μm, and most preferably 5 μm to 14 μm. In some cases, the thickness of the second pressure-sensitive adhesive sheet may be 5 μm to 200 μm, 5 μm to 170 μm, 5 μm to 150 μm, 5 μm to 130 μm, 5 μm to 110 μm, or even 40 μm to 100 μm.

[0132] ≪2-4. Third adhesive sheet≫ Any suitable adhesive sheet can be used as the third adhesive sheet as long as it does not impair the effects of the present invention. The third adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0133] The thickness of the third pressure-sensitive adhesive sheet is preferably 5 μm to 20 μm, more preferably 5 μm to 17 μm, even more preferably 5 μm to 16 μm, particularly preferably 5 μm to 15 μm, and most preferably 5 μm to 14 μm. In some cases, the thickness of the third pressure-sensitive adhesive sheet may be 5 μm to 200 μm, 5 μm to 170 μm, 5 μm to 150 μm, 5 μm to 130 μm, 5 μm to 110 μm, or even 40 μm to 100 μm.

[0134] ≪2-5. Fourth adhesive sheet≫ Any suitable adhesive sheet can be used as the fourth adhesive sheet as long as it does not impair the effects of the present invention. The fourth adhesive sheet may be the adhesive sheet 10 described in the section <<1. Adhesive Sheet>>>, or may be one using a known adhesive.

[0135] The thickness of the fourth adhesive sheet is preferably 1 μm to 60 μm, and more preferably 5 μm to 30 μm. In one embodiment of the present invention (FIG. 6), the optical laminate includes a fourth adhesive sheet, but the optical laminate does not necessarily need to include a fourth adhesive sheet.

[0136] 2-6. First optical member Any suitable optical member can be used as the first optical member as long as it does not impair the effects of the present invention. Examples of the first optical member include a cover glass, a thin glass, a protective film, an anti-reflection laminate, and an anti-sunglasses laminate.

[0137] The thickness of the first optical member is, for example, 1 μm to 1000 μm, and may be 10 μm to 500 μm, 20 μm to 200 μm, 40 μm to 120 μm, or even 70 μm to 100 μm.

[0138] One embodiment of the first optical member is thin glass. In this specification, thin glass refers to an extremely thin glass film having a thickness of 200 μm or less. Thin glass obtained by any appropriate manufacturing method can be used. Typically, thin glass is produced by melting a mixture containing a main raw material such as silica or alumina, an antifoaming agent such as mirabilite or antimony oxide, and a reducing agent such as carbon at a temperature of 1400°C to 1600°C, forming it into a thin plate, and then cooling it.

[0139] Examples of methods for forming thin glass include the slot downdraw method, the fusion method, and the float method. Among these, thin glass formed by the fusion method does not require polishing treatment because the surface is not contaminated with tin or the like as in the case of glass formed by the float method, and it is possible to ensure surface smoothness and thinness. From these viewpoints, it is preferable to use the fusion method.

[0140] The thickness of the thin glass is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and particularly preferably 30 μm to 100 μm.

[0141] Another embodiment of the first optical member is a protective film. Specific examples of materials that form the main component of the protective film include the same materials that form the main component of the protective layer described below in Section <2-9-b. Protective Layer> (transparent resins, thermosetting or ultraviolet-curing resins, glassy polymers, and resin compositions). In one embodiment of the present invention, the protective film contains a polyester resin such as polyethylene terephthalate (PET). The protective film may be subjected to a surface treatment described below in Section <2-9-b. Protective Layer>.

[0142] Another embodiment of the first optical member is an antireflection laminate. The antireflection laminate typically includes a first substrate, a hard coat layer disposed on the first substrate, and an antireflection layer disposed on the hard coat layer. The hard coat layer may be formed directly on the viewer-side surface of the first substrate. The antireflection layer may be formed directly on the viewer-side surface of the hard coat layer. The antireflection laminate may be a member having a laminated structure of antireflection layer / hard coat layer / first substrate. The antireflection laminate has a first substrate laminated with a first pressure-sensitive adhesive sheet.

[0143] <2-6-a. First base material> The first substrate is typically used to form a hard coat layer and an anti-reflection layer. Any appropriate resin film can be used as the first substrate. Examples of materials for forming the first substrate include polyester resins such as polyethylene terephthalate (PET), cycloolefin resins such as norbornene resins, resins (COC) obtained by addition polymerization of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene), and cellulose resins such as triacetyl cellulose (TAC). One embodiment of the first substrate includes a cellulose resin such as TAC.

[0144] The thickness of the first substrate can be appropriately set depending on the purpose. The thickness of the first substrate is typically 20 μm to 200 μm, preferably 50 μm to 150 μm, and more preferably 70 μm to 90 μm.

[0145] <2-6-b. Hard Coat Layer> The hard coat layer can impart, for example, excellent pencil hardness to the optical laminate. Furthermore, by appropriately adjusting the difference in refractive index between the hard coat layer and the antireflection layer, the reflectance of the optical laminate can be further reduced.

[0146] The hard coat layer preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. The hard coat layer can be formed from any appropriate resin as long as it has such desired properties. Specific examples of the resin include thermosetting resins, thermoplastic resins, ultraviolet curing resins, electron beam curing resins, and two-component mixed resins. Among the resins that form the hard coat layer, ultraviolet curing resins are preferred. When the resin is an ultraviolet curing resin, the hard coat layer can be formed with simple operation and high efficiency.

[0147] Specific examples of ultraviolet-curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based ultraviolet-curable resins. Examples of ultraviolet-curable resins include ultraviolet-curable monomers, oligomers, and polymers. Examples of preferred ultraviolet-curable resins include resin compositions containing acrylic monomer or oligomer components having preferably two or more, and more preferably three to six, ultraviolet-polymerizable functional groups. Typically, ultraviolet-curable resins contain a photopolymerization initiator.

[0148] The hard coat layer can be formed by any appropriate method, for example, by coating a resin composition for forming a hard coat layer on a first substrate, drying the coating, and curing the dried coating by irradiating it with ultraviolet light.

[0149] The thickness of the hard coat layer is, for example, 0.5 μm to 20 μm, and preferably 1 μm to 15 μm.

[0150] Details of the hard coat layer and the adhesion structure between the hard coat layer and the antireflection layer are described in, for example, JP 2016-224443 A, the disclosure of which is incorporated herein by reference.

[0151] <2-6-c. Anti-reflection layer> The antireflection layer is provided to prevent reflection of external light (e.g., fluorescent light) and the like. Any appropriate configuration can be adopted as the configuration of the antireflection layer. Typical configurations of the antireflection layer include: (1) a single layer of a low refractive index layer having an optical film thickness of 120 nm to 140 nm and a refractive index of about 1.35 to 1.55; (2) a laminate having, from the first substrate, a medium refractive index layer, a high refractive index layer, and a low refractive index layer in this order; and (3) an alternating multilayer laminate of a high refractive index layer and a low refractive index layer.

[0152] Examples of materials that can form a low refractive index layer include silicon oxide (SiO2) and magnesium fluoride (MgF2). The refractive index of a low refractive index layer is typically about 1.35 to 1.55. Examples of materials that can form a high refractive index layer include titanium oxide (TiO2), niobium oxide (Nb2O3 or Nb2O5), tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), and ZrO2-TiO2. The refractive index of a high refractive index layer is typically about 1.60 to 2.20. Examples of materials that can form a medium refractive index layer include titanium oxide (TiO2) and a mixture of a material that can form a low refractive index layer and a material that can form a high refractive index layer (for example, a mixture of titanium oxide and silicon oxide). The refractive index of a medium refractive index layer is typically about 1.50 to 1.85. The thicknesses of the low refractive index layer, the medium refractive index layer and the high refractive index layer can be set so as to achieve an appropriate optical film thickness depending on the layer structure of the antireflection layer, the desired antireflection performance and the like.

[0153] The antireflection layer is typically formed by a dry process. Specific examples of the dry process include PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). Examples of the PVD method include vacuum deposition, reactive vapor deposition, ion beam assisted deposition, sputtering, and ion plating. Examples of the CVD method include plasma CVD. The dry process for forming the antireflection layer is preferably sputtering.

[0154] The thickness of the antireflection layer is, for example, about 20 nm to 300 nm.

[0155] The difference between the maximum reflectance and the minimum reflectance of the antireflection layer in the wavelength range of 400 nm to 700 nm is preferably 2.0% or less, more preferably 1.9% or less, and even more preferably 1.8% or less. If the difference between the maximum reflectance and the minimum reflectance is in this range, coloring of reflected light can be effectively prevented.

[0156] The antireflection layer is typically located on the outermost surface of the optical laminate on the viewing side. The moisture permeability of the antireflection layer is typically 1.0 g / mm 2 or less, preferably 0.01 g / mm 2 ~0.1g / mm 2 The moisture permeability is measured in accordance with the moisture permeability test (cup method) of JIS Z0208 (for example, JIS Z0208:1976), in an atmosphere at a temperature of 40°C and a humidity of 92% RH, over an area of ​​1 m 2 When the moisture permeability of the antireflection layer positioned on the outermost surface is equal to or less than the upper limit, warping of the optical laminate in a high-humidity environment can be stably suppressed.

[0157] The antireflection layer does not have to be located on the outermost surface of the optical laminate. The antireflection laminate may have an outermost layer on the viewing side of the antireflection layer, if necessary. That is, the antireflection laminate may be composed of a first substrate, a hard coat layer, an antireflection layer, and an outermost layer. The moisture permeability range of the outermost layer is the same as that of the antireflection layer described above. Examples of the outermost layer include an antifouling layer. The antifouling layer contains, for example, a fluorine group-containing silane compound (e.g., an alkoxysilane compound having a perfluoropolyether group) or a fluorine group-containing organic compound. The antifouling layer preferably exhibits water repellency with a water contact angle of 110 degrees or more.

[0158] 2-7. Second optical member Any appropriate optical member can be used as the second optical member as long as it does not impair the effects of the present invention. Examples of the second optical member include thin glass, protective films, functional films, and laminates thereof.

[0159] The thickness of the second optical member is, for example, 10 μm to 500 μm, and may be 10 μm to 200 μm, 20 μm to 70 μm, or even 30 μm to 50 μm.

[0160] One embodiment of the second optical member is thin glass, and examples of thin glass include those described in <<2-6. First Optical Member>>.

[0161] Another embodiment of the second optical member is a protective film. Examples of the protective film include those described in Section 2-6. First Optical Member. In one embodiment of the present invention, the protective film serving as the second optical member contains a (meth)acrylic resin, and preferably contains a (meth)acrylic resin having a glutarimide structure.

[0162] Another embodiment of the second optical member is a functional film, such as a brightness enhancement film or a touch sensor film.

[0163] 2-8. Third optical member Any appropriate optical member can be used as the third optical member as long as it does not impair the effects of the present invention. Examples of the third optical member include an anti-glare laminate and an anti-sunglasses laminate.

[0164] The thickness of the third optical member is typically 20 μm to 60 μm, and preferably 30 μm to 50 μm.

[0165] One embodiment of the third optical member is an anti-glare laminate. The anti-glare laminate includes an anti-glare layer and a second substrate disposed on the viewing side of the anti-glare layer. The anti-glare layer is supported by the second substrate. The anti-glare layer is in contact with a third adhesive sheet and is pressure-sensitively adhered to the third adhesive sheet. The second substrate is located on the opposite side of the anti-glare layer from the third adhesive sheet. The second substrate is in contact with the second adhesive sheet and is pressure-sensitively adhered to the second adhesive sheet.

[0166] <2-8-a. Anti-glare layer> The anti-glare layer is provided to prevent reflections of the face of a user of the image display device, the keyboard of the image display device, external light (e.g., fluorescent light), etc. In one embodiment of the present invention, the anti-glare layer is a layer of a liquid crystal compound with a fixed orientation. In this specification, the term "fixed orientation layer" refers to a layer in which the liquid crystal compound is oriented in a predetermined direction within the layer and the orientation state is fixed. The term "fixed orientation layer" encompasses a hardened orientation layer obtained by hardening a liquid crystal monomer. The liquid crystal compound may be a rod-shaped liquid crystal compound, a discotic (discotic) liquid crystal compound, or a combination thereof.

[0167] In one embodiment of the present invention, the anti-glare layer contains a discotic liquid crystal compound. More specifically, the anti-glare layer is a layer in which the discotic liquid crystal compound is fixed in a state where it is aligned in a predetermined direction. A discotic liquid crystal compound generally refers to a liquid crystal compound having a discotic molecular structure in which a cyclic core such as benzene, 1,3,5-triazine, or calixarene is located at the center of the molecule and linear alkyl groups, alkoxy groups, substituted benzoyloxy groups, or the like are radially substituted as side chains. Representative examples of discotic liquid crystals include benzene derivatives, triphenylene derivatives, truxene derivatives, and phthalocyanine derivatives described in the research report by C. Destrade et al., Mol. Cryst. Liq. Cryst., Vol. 71, p. 111 (1981); cyclohexane derivatives described in the research report by B. Kohne et al., Angew. Chem., Vol. 96, p. 70 (1984); and azacrown and phenylacetylene macrocycles described in the research report by J. M. Lehn et al., J. Chem. Soc. Chem. Commun., p. 1794 (1985) and the research report by J. Zhang et al., J. Am. Chem. Soc., Vol. 116, p. 2655 (1994). Further specific examples of discotic liquid crystal compounds include compounds described in JP-A-2006-133652, JP-A-2007-108732, JP-A-2010-244038, and JP-A-2014-214177. The descriptions in the above documents and publications are incorporated herein by reference. An antiglare layer containing a discotic liquid crystal compound can typically be a so-called negative A plate having a refractive index characteristic of nx = nz > ny.

[0168] In another embodiment, the anti-glare layer contains a rod-shaped liquid crystal compound. More specifically, the anti-glare layer is oriented (homogeneous orientation) with the rod-shaped liquid crystal compounds aligned in a predetermined direction (typically, the slow axis direction). Examples of rod-shaped liquid crystal compounds include liquid crystal compounds having a nematic liquid crystal phase (nematic liquid crystals). Examples of such liquid crystal compounds that can be used include liquid crystal polymers and liquid crystal monomers. The mechanism by which the liquid crystal compound exhibits liquid crystallinity may be either lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used alone or in combination. Any appropriate liquid crystal monomer may be used as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445 can be used. Specific examples of such polymerizable mesogenic compounds include BASF's LC242 (trade name), Merck's E7 (trade name), and Wacker-Chem's LC-Sillicon-CC3767 (trade name). Nematic liquid crystal monomers are preferred as liquid crystal monomers. Specific examples of liquid crystal compounds are described in JP-A-2006-163343, for example. The disclosures of these publications are incorporated herein by reference. The anti-glare layer containing a rod-like liquid crystal compound can be typically a so-called positive A plate having refractive index characteristics of nx>ny=nz.

[0169] The anti-glare layer can typically function as a λ / 2 plate. When the anti-glare layer functions as a λ / 2 plate, glare can be effectively prevented by controlling its orientation angle (or slow axis direction). The in-plane retardation Re(550) of such an anti-glare layer is 220 nm to 320 nm, more preferably 240 nm to 300 nm, and even more preferably 250 nm to 280 nm.

[0170] The angle formed by the slow axis of the anti-glare layer and the absorption axis of the polarizer is preferably 35° to 55°, more preferably 40° to 50°, and even more preferably about 45°. By arranging the anti-glare layer, which functions as a λ / 2 plate, at such an axis angle, it is possible to effectively prevent glare.

[0171] The thickness of the anti-glare layer is preferably 1 μm to 5 μm, and more preferably 1 μm to 3 μm.

[0172] When an alignment film is used to align the liquid crystal compound, the anti-glare laminate further includes an alignment film between the anti-glare layer and the second substrate. That is, the anti-glare laminate may be composed of an anti-glare layer, an alignment film, and a second substrate. The alignment film generally contains a polymer material as a main component. Representative examples of polymer materials include polyvinyl alcohol, polyimide, and their derivatives. In one embodiment of the present invention, modified or unmodified polyvinyl alcohol is preferred. For example, the modified polyvinyl alcohol described in WO 01 / 88574 A1 and Japanese Patent No. 3907735 can be used as the alignment film. The alignment film is typically subjected to an alignment treatment. Representative examples of alignment treatment include rubbing treatment and photo-alignment treatment. Since rubbing treatment is well known in the art, a detailed description will be omitted. Examples of photo-aligned alignment films (photo-alignment films) include those described in WO 2005 / 096041 and the product LPP-JP265CP manufactured by Rolic Technologies. The thickness of the alignment film is, for example, 0.01 μm to 10 μm, preferably 0.01 μm to 1 μm, and more preferably 0.01 μm to 0.5 μm.

[0173] The anti-glare layer can be formed, for example, by the following procedure. First, a coating liquid for forming an alignment film is applied to a second substrate and dried to form a coating film. This coating film is rubbed in a predetermined direction to form an alignment film on the second substrate. This predetermined direction may correspond to the slow axis direction of the resulting anti-glare layer. Next, a coating liquid for forming an anti-glare layer (e.g., a solution containing a liquid crystal compound and, if necessary, a crosslinkable monomer) is applied to the formed alignment film and heated. Heating removes the solvent from the coating liquid and promotes the alignment of the liquid crystal compound. Heating can be performed in a single step or in multiple steps at different temperatures. Next, ultraviolet light is irradiated to crosslink (or polymerize) the crosslinkable (or polymerizable) monomer, thereby fixing the alignment of the liquid crystal compound. In this way, an anti-glare layer is formed on the second substrate (substantially, on the alignment film). A method for aligning discotic liquid crystal compounds is described, for example, in JP 2014-214177 A, and a method for aligning rod-shaped liquid crystal compounds is described, for example, in JP 2006-163343 A. The descriptions of these publications are incorporated herein by reference. The alignment film may be omitted depending on the desired alignment state and the type of liquid crystal compound.

[0174] <2-8-b.Second base material> The second substrate may be used to form an anti-glare layer.

[0175] Any suitable resin film can be used as the second substrate. Examples of materials for forming the resin film include polyester resins such as polyethylene terephthalate (PET), cycloolefin resins such as norbornene resins, resins (COC) obtained by addition polymerization of cycloolefins (e.g., norbornene) and α-olefins (e.g., ethylene), and cellulose resins such as triacetyl cellulose (TAC). In one embodiment of the present invention, the second substrate includes a cellulose resin such as TAC.

[0176] The thickness of the second substrate can be appropriately set depending on the purpose. The thickness of the second substrate is typically 20 μm to 200 μm, preferably 25 μm to 100 μm, and more preferably 30 μm to 50 μm.

[0177] ≪2-9. Polarizing film≫ A polarizing film typically includes a polarizer and a protective layer disposed on the viewing side of the polarizer. The protective layer is typically attached to the polarizer via any appropriate adhesive layer. That is, the polarizing film may be composed of a polarizer, an adhesive layer, and a protective layer.

[0178] 6, the protective layer is located between the polarizer and the first adhesive sheet 10A and is in contact with the first adhesive sheet 10A. The protective layer may be pressure-sensitively adhered to the first adhesive sheet 10A. The polarizing film may further include a second protective layer, and the polarizer may be located between the protective layer and the second protective layer.

[0179] <2-9-a. Polarizer> Any appropriate polarizer can be used as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0180] Specific examples of polarizers composed of a single-layer resin film include PVA-based resin films that have been subjected to a dyeing treatment with iodine and a stretching treatment (typically, uniaxial stretching). Dyeing with iodine is performed, for example, by immersing the PVA-based resin film in an aqueous iodine solution. The stretching ratio is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, the film may be dyed after stretching. If necessary, the PVA-based resin film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA-based resin film in water and washing it before dyeing, it is possible to clean off stains and antiblocking agents on the surface of the PVA-based resin film and also to swell the PVA-based resin film, thereby preventing uneven dyeing and the like.

[0181] Specific examples of polarizers composed of a laminate of two or more layers include a polarizer composed of a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer composed of a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer composed of a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In a preferred embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may optionally further involve in-air stretching the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. Additionally, in a preferred embodiment, the laminate is subjected to a drying shrinkage treatment in which the laminate is heated while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the laminate is subjected to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of the PVA, even when the PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of the PVA in advance, problems such as a decrease in the orientation or dissolution of the PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through treatment steps in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment. Furthermore, the drying shrinkage treatment causes the laminate to shrink in the width direction, thereby improving the optical properties.The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such a method for producing a polarizer are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0182] The polarizer is preferably composed of a laminate of two or more layers, and more preferably composed of a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate.

[0183] The thickness of the polarizer may be any appropriate thickness as long as the effects of the present invention are not impaired. In terms of further exhibiting the effects of the present invention, the thickness of the polarizer is preferably 1 μm to 15 μm, more preferably 2 μm to 12 μm, even more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm.

[0184] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0185] <2-9-b. Protective layer> The protective layer may be formed of any suitable film that can be used as a protective layer for a polarizer. Examples of materials that form the main component of the film include transparent resins such as cellulose resins (e.g., triacetyl cellulose (TAC)), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, (meth)acrylic resins, and acetate resins. Examples of materials that form the main component of the film include thermosetting or ultraviolet-curing resins (e.g., (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins). Other examples of materials that form the main component of the film include glassy polymers (e.g., siloxane polymers) and polymer films described in JP 2001-343529 A (WO 01 / 37007). Furthermore, the main component of the film may be, for example, a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in the side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in the side chains. For example, a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer may be used. The film may be, for example, an extrusion molded product of such a resin composition.

[0186] In one embodiment, the protective layer contains a (meth)acrylic resin. For example, a (meth)acrylic resin having a glutarimide structure is used as the (meth)acrylic resin. Examples of (meth)acrylic resins having a glutarimide structure are described in JP 2006-309033 A, JP 2006-317560 A, JP 2006-328329 A, JP 2006-328334 A, JP 2006-337491 A, JP 2006-337492 A, JP 2006-337493 A, JP 2006-337569 A, JP 2007-009182 A, JP 2009-161744 A, and JP 2010-284840 A. These descriptions are incorporated herein by reference.

[0187] The thickness of the protective layer may be any appropriate thickness as long as it does not impair the effects of the present invention. In order to further exhibit the effects of the present invention, the thickness of the protective layer is typically 300 μm or less, preferably 3 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. In addition, when the protective layer is subjected to a surface treatment, the thickness of the protective layer includes the thickness of the layer formed by the surface treatment (surface treatment layer).

[0188] 2-10. First Phase Difference Film The first retardation film may be composed of a retardation film having any appropriate optical and / or mechanical properties depending on the purpose. The first retardation film is located on the side opposite the viewing side of the polarizing film. The first retardation film is typically attached to the side opposite the viewing side of the polarizing film via any appropriate adhesive layer. The first retardation film may also serve as a protective layer on the side opposite the viewing side of the polarizer.

[0189] The thickness of the first retardation film is preferably 10 μm to 60 μm, and more preferably 30 μm to 50 μm.

[0190] The in-plane retardation Re(550) of the first retardation film is preferably 80 nm to 150 nm, more preferably 90 nm to 140 nm, and further preferably 100 nm to 130 nm.

[0191] The first retardation film preferably has refractive index characteristics that satisfy the relationship nx>ny>nz. The Nz coefficient of the first retardation film is preferably 1.1 to 3.0, and more preferably 1.3 to 2.7.

[0192] The first retardation film can preferably be arranged so that its slow axis is substantially parallel to the absorption axis of the polarizer. In this specification, the terms "substantially parallel" and "almost parallel" include the case where the angle between the two directions is 0°±7°, preferably 0°±5°, and more preferably 0°±3°. The terms "substantially orthogonal" and "almost orthogonal" include the case where the angle between the two directions is 90°±7°, preferably 90°±5°, and more preferably 90°±3°. Furthermore, in this specification, when simply referring to "orthogonal" or "parallel," it can include a substantially orthogonal or substantially parallel state.

[0193] The absolute value of the photoelastic coefficient of the first retardation film is preferably 2×10 -11 m 2 The absolute value of the photoelastic coefficient is preferably 2.0×10 -13 m 2 / N~1.5×10 -11 m 2 / N, and more preferably 1.0 × 10 -12 m 2 / N~1.2×10 -11 m 2 / N. By appropriately adjusting the photoelastic coefficient of the first retardation film, an optical laminate suitable for suppressing display defects can be obtained even when a small object collides with or presses the screen over a small contact area. If the absolute value of the photoelastic coefficient is within this range, phase difference change is unlikely to occur when shrinkage stress occurs during heating. Therefore, by forming the first retardation film using a resin having such an absolute value of the photoelastic coefficient, thermal unevenness can be effectively prevented when the optical laminate is applied to an image display device.

[0194] The first retardation film may exhibit a reverse wavelength dispersion characteristic in which the retardation value increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the retardation value decreases with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the retardation value changes little with the wavelength of the measurement light. The first retardation film preferably exhibits a flat wavelength dispersion characteristic. Specifically, the Re(450) / Re(550) of the first retardation film is preferably 0.99 to 1.03, and the Re(650) / Re(550) is preferably 0.98 to 1.02. By arranging a λ / 2 plate (first retardation film) and a λ / 4 plate (second retardation film) having flat wavelength dispersion characteristics at a predetermined axial angle, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, resulting in excellent antireflection properties.

[0195] The first retardation film may be made of any suitable resin film that satisfies the above-mentioned characteristics. Typical examples of such resins include cyclic olefin resins, polycarbonate resins, cellulose resins, polyester resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. Among these, cyclic olefin resins are preferably used. The first retardation film can be obtained, for example, by stretching a film formed from the above-mentioned resin. Details of cyclic olefin resins and methods for stretching resin films (methods for forming retardation films) are described, for example, in JP 2015-210459 A and JP 2016-105166 A. The disclosures of these publications are incorporated herein by reference.

[0196] 2-11. Second Phase Difference Film The second retardation film may be composed of a retardation film having any suitable optical and / or mechanical properties depending on the purpose. The second retardation film is located on the opposite side of the first retardation film from the viewing side. The second retardation film is typically attached to the opposite side of the first retardation film from the viewing side via any suitable adhesive layer.

[0197] The thickness of the second retardation film is preferably 10 μm to 50 μm, and more preferably 20 μm to 40 μm.

[0198] The in-plane retardation Re(550) of the second retardation film is preferably 10 nm to 60 nm, more preferably 20 nm to 50 nm, and further preferably 30 nm to 40 nm.

[0199] The second retardation film preferably has refractive index characteristics that satisfy the relationship nz>nx>ny. The Nz coefficient of the second retardation film is preferably from -10 to -0.1, and more preferably from -5 to -1.

[0200] The second retardation film can be preferably disposed so that its slow axis is substantially perpendicular to the absorption axis of the polarizer.

[0201] The second retardation film may be composed of any appropriate resin film that can satisfy the above-mentioned characteristics. Such a resin may typically be a polymer having negative intrinsic birefringence. A polymer having negative intrinsic birefringence refers to a polymer in which, when oriented by stretching or the like, the refractive index in the orientation direction becomes relatively small. Examples of polymers having negative intrinsic birefringence include those in which a chemical bond or functional group with large polarization anisotropy, such as an aromatic or carbonyl group, is introduced into the side chain of the polymer. Specific examples include modified polyolefin-based resins (e.g., modified polyethylene-based resins), acrylic-based resins, styrene-based resins, maleimide-based resins, and fumaric acid ester-based resins. The second retardation film may be obtained, for example, by appropriately stretching a film formed from the above-mentioned resin.

[0202] In one embodiment of the present invention, the optical stack includes a first retardation film and a second retardation film, but the optical stack does not necessarily include the first retardation film and / or the second retardation film.

[0203] ≪≪3. Image display device≫≫ The optical laminate according to the embodiment of the present invention can be applied to an image display device. Therefore, one embodiment of the present invention also includes an image display device using such an optical laminate. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. The image display device according to the embodiment of the present invention is preferably an organic EL display device. In other words, the pressure-sensitive adhesive sheet or optical laminate according to the embodiment of the present invention is preferably a component used in an organic EL display device.

[0204] An image display device according to an embodiment of the present invention typically includes an optical laminate according to an embodiment of the present invention on its viewing side. The image display device includes an image display panel. The image display panel includes an image display cell. Note that the image display device may be referred to as an optical display device, the image display panel may be referred to as an optical display panel, and the image display cell may be referred to as an optical display cell. [Example]

[0205] The present invention will be specifically described below using examples, but the present invention is not limited to these examples. The test and evaluation methods used in the examples are as follows. The term "parts" means "parts by weight" unless otherwise specified, and the term "%" means "% by weight" unless otherwise specified.

[0206] <Production of Photocurable Composition (I-1)> 83.3 parts by weight of n-butyl acrylate (BA), 4.2 parts by weight of acrylic acid (AA), 12.5 parts by weight of N-acryloylmorpholine (ACMO), and 0.2 parts by weight of 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (trade name "Omnirad127D", IGM Resins BV) as a photopolymerization initiator were placed in a four-neck flask and irradiated with UV light under a nitrogen atmosphere to obtain a partially photopolymerized monomer syrup (photocurable composition (I-1)). UV irradiation was continued until the viscosity of the liquid in the flask reached approximately 20 Pa·s. The viscosity was measured using a BH viscometer No. 5 rotor at 10 rpm and a measurement temperature of 30°C.

[0207] <Production of Photocurable Compositions (I-2) to (I-6)> Photocurable compositions (I-2) to (I-6) were produced in the same manner as for photocurable composition (I-1), except that the type and content of the monomers were changed as shown in Table 1 and that a crosslinking agent was further added after the formation of the monomer syrup.

[0208] [Gel fraction G1] The gel fraction G1 of the prepared photocurable composition (I) after curing was measured by the following method. First, the photocurable composition (I) was applied with an applicator onto the release-treated surface of a first release liner (trade name "Diafoil MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side, to form a coating layer. Next, the release-treated surface of a second release liner (trade name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the coating layer formed on the first release liner. Next, an LED (peak wavelength 340 nm, illuminance 9 mW / cm) was irradiated onto the coating layer between the release liners from the first release liner side. 2 , cumulative light intensity 2700mJ / cm 2 ) was irradiated with light. As a result, the coating layer was sufficiently cured to obtain a cured layer.

[0209] The gel fraction of the resulting cured product layer was calculated by the method described above, and the calculated value was identified as the gel fraction G1 of the photocurable composition (I) after curing.

[0210] [Table 1]

[0211] The abbreviations in Table 1 are as follows: BA: n-butyl acrylate AA: acrylic acid ACMO: acryloylmorpholine NVP: N-vinylpyrrolidone BzA: benzyl acrylate NDDA: 1,9-nonanediol diacrylate Omnirad127D:2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one (product name "Omnirad127D", manufactured by IGM Resins BV)

[0212] <Production of Photocurable Composition (II-1)> A photocurable composition (II-1) was prepared by mixing 100 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent (photopolymerizable compound), 3.0 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad819", manufactured by IGM Resins BV) as a photopolymerization initiator, and 103 parts by weight of ethyl acetate as a solvent.

[0213] <Production of Photocurable Composition (II-2)> A photocurable composition (II-2) was prepared by mixing 100 parts by weight of n-butyl acrylate (BA), 0.05 parts by weight of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent, 3.0 parts by weight of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad819", manufactured by IGM Resins BV) as a photopolymerization initiator, and 103 parts by weight of ethyl acetate as a solvent.

[0214] [Gel fraction G2] The gel fraction G2 after curing of the prepared photocurable composition (II) was determined by the following method. First, a composition was prepared having the same composition as the above-mentioned photocurable composition (II-1) or photocurable composition (II-2), except that it did not contain a solvent. The composition was applied with an applicator to the release-treated surface of a first release liner (trade name "Diafoil MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side, to form a coating layer. Next, the release-treated surface of a second release liner (trade name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the coating layer formed on the first release liner. Next, a black light (manufactured by Toshiba, wavelength 320 nm to 400 nm, illuminance 2.5 mW / cm) was applied to the coating layer between the release liners from the first release liner side. 2 , cumulative light intensity 2400mJ / cm 2 ) was irradiated with light. As a result, the coating layer was sufficiently cured to obtain a cured layer.

[0215] The gel fraction of the resulting cured product layer was calculated by the method described above, and the calculated value was identified as the gel fraction G2 of the photocurable composition (II) after curing.

[0216] [Table 2]

[0217] The abbreviations in Table 2 are as follows: BA: n-butyl acrylate NDDA: 1,9-nonanediol diacrylate Omnirad819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Omnirad819", manufactured by IGM Resins BV)

[0218] Example 1 First, a photocurable composition (I-1) was applied with an applicator to the release-treated surface of a first release liner (trade name "Diafoil MRF", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side, to form a coating layer. Next, the release-treated surface of a second release liner (trade name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the coating layer formed on the first release liner. Next, an LED (peak wavelength 340 nm, illuminance 9 mW / cm) was applied to the coating layer between the release liners from the first release liner side. 2 , cumulative light intensity 2700mJ / cm 2 ) was irradiated with light. As a result, the coating layer was photocured, and a laminate composed of the first release liner / cured product layer (thickness 80 μm) / second release liner was formed.

[0219] Next, the second release liner was peeled off from the resulting laminate, and a photocurable composition (II-1) was applied to the exposed surface of the cured layer. The amount of photocurable composition (II-1) applied was determined so that the total solids content excluding the solvent in the photocurable composition (II-1) was 20 parts by weight relative to 80 parts by weight of the photocurable composition (I-1) used to form the cured layer, resulting in a coating thickness of approximately 40 μm. Next, the laminate was dried for 3 minutes in a dryer at 110°C. The application and drying processes allowed the photocurable composition (II-1) to penetrate into the cured layer and also evaporated the solvent. This resulted in a precursor layer of a pressure-sensitive adhesive sheet.

[0220] Next, the release-treated surface of a third release liner (product name "Diafoil MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the precursor layer on the first release liner. Next, a black light (manufactured by Toshiba, wavelength 320 nm to 400 nm, illuminance 2.5 mW / cm) was irradiated onto the precursor layer between the release liners from the side of the first release liner. 2 , cumulative light intensity 2400mJ / cm 2 ) was irradiated with light. This photocured the precursor layer, forming the pressure-sensitive adhesive sheet (thickness 100 μm) of Example 1. In detail, a laminate composed of a first release liner / pressure-sensitive adhesive sheet (thickness 100 μm) / third release liner was formed.

[0221] (Examples 2 to 5 and Comparative Examples 1 and 2) Pressure-sensitive adhesive sheets of Examples 2 to 5 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the types of photocurable compositions (I) and (II) were changed as shown in Table 3. In Comparative Example 1, the photocurable composition (II) was not applied to the cured product layer, and the cured product layer of the photocurable composition (I) was regarded as the pressure-sensitive adhesive sheet.

[0222] [Piercing test] The produced adhesive sheet was subjected to a puncture test using the following method (Figure 7). First, the third release liner was peeled off from a laminate consisting of a first release liner / adhesive sheet 10 / third release liner, and a Prescale 1 (manufactured by Fujifilm Corporation, medium pressure (MS), thickness 100 μm) was attached to the exposed surface of the adhesive sheet 10. The Prescale is a pressure measurement film configured to color areas where a specific pressure (10 to 50 MPa) is applied. Next, the Prescale 1 was brought into contact with a 1.2 mm thick glass plate 5, and the first release liner was peeled off to obtain a laminate S consisting of the glass plate 5 / Prescale 1 / adhesive sheet 10.

[0223] The obtained laminate S was placed on the stage of a measuring device (manufactured by Instron, product name "5581") equipped with a piercing jig 6. The radius of curvature R of the tip of the piercing jig 6 was 550 μm. A piercing test was carried out using the piercing jig 6 to pierce the laminate S from the pressure-sensitive adhesive sheet 10 side at room temperature (23°C ± 3°C) at a piercing speed of 0.9 mm / min until a load of 0.2 kgf was reached. In the piercing test, the piercing jig 6 continued to pierce the laminate S so that the load was maintained for 20 seconds after the load reached 0.2 kgf.

[0224] After the puncture test, the prescale 1 was removed from the laminate S, and the surface of the prescale 1 at the position where the load was applied by the puncture jig 6 was observed with an optical microscope (Keyence Corporation, VHX-8000). The observation with the optical microscope was performed under conditions of a magnification of 300x and a field of view of 840 μm × 1120 μm. Next, the microscope image showing the field of view was converted to an HSB Stack image type using software (ImageJ) and binarized. In the binarization process, the minimum darkness value was set to 0, the maximum darkness value to 255, and the darkness threshold value was set to 30. Specifically, areas of the microscope image with a darkness value of less than 30 were converted to white areas (darkness 0), and areas with a darkness value of 30 or more were converted to black areas (darkness 255). Next, from the image after binarization, the areas that were colored (black areas) due to the load applied to the prescale 1 in the puncture test were identified, and their area (colored area) (μm 2 ) was calculated. Furthermore, the area of ​​the visual field range (940800 μm 2 ) to colored area (μm 2 ) ratio (coloring ratio) was identified.

[0225] [Table 3]

[0226] As can be seen from Table 3, the adhesive sheet of the example prepared by combining the photocurable compositions (I) and (II) in which the gel fraction G1 and the gel fraction G2 satisfy X < Y had a lower coloring ratio of the press scale in the piercing test than the comparative example. From this result, it is presumed that the adhesive sheet of the example is suitable for dispersing stress when a local load is applied. That is, it can be said that the adhesive sheet of the example is suitable for suppressing damage to the image display panel due to a local load.

Industrial Applicability

[0227] The adhesive sheet according to an embodiment of the present invention can be suitably used for an image display device (typically, a liquid crystal display device, an organic EL display device).

Explanation of Signs

[0228] 10 Adhesive sheet 30 First optical member 31 Second optical member 32 Third optical member 100, 110, 120, 130 Optical laminate

Claims

1. a polymer P1 formed from a photocurable composition (I) having a gel fraction G1 of X (%) after curing; a polymer P2 formed from a photocurable composition (II) having a gel fraction G2 of Y (%) after curing; Including, The gel fraction G1 and the gel fraction G2 satisfy X<Y. Adhesive sheet.

2. The pressure-sensitive adhesive sheet according to claim 1 , wherein the gel fraction G1 and the gel fraction G2 satisfy 0.01≦X / Y<1.

0.

3. The pressure-sensitive adhesive sheet according to claim 1 , wherein the gel fraction G1 satisfies 1.0%≦X≦90%.

4. The pressure-sensitive adhesive sheet according to claim 1 , wherein the gel fraction G2 satisfies 60%≦Y≦99.9%.

5. The pressure-sensitive adhesive sheet according to claim 1 , wherein the photocurable composition (I) contains a monomer component.

6. The pressure-sensitive adhesive sheet according to claim 5 , wherein the monomer component comprises at least one selected from the group consisting of an acidic group-containing monomer and a nitrogen atom-containing monomer.

7. The pressure-sensitive adhesive sheet according to claim 5 , wherein the photocurable composition (I) further contains a crosslinking agent.

8. The pressure-sensitive adhesive sheet according to claim 1 , wherein the photocurable composition (II) contains a polyfunctional (meth)acrylate.

9. The pressure-sensitive adhesive sheet according to claim 1 , wherein the photocurable composition (I) and the photocurable composition (II) do not contain an ultraviolet absorber.

10. The pressure-sensitive adhesive sheet according to claim 1 , obtained by adding the photocurable composition (II) to a cured layer formed from the photocurable composition (I) and curing the resulting mixture.

11. A method for producing the pressure-sensitive adhesive sheet according to any one of claims 1 to 10, comprising: The production method is a method for producing a pressure-sensitive adhesive sheet, comprising the steps of adding the photocurable composition (II) to a cured layer formed from the photocurable composition (I) and curing the composition.

12. An optical laminate comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 10 and an optical member.

13. An image display device comprising the optical laminate according to claim 12.

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