Optical laminate, image display device, and method for manufacturing optical laminate

Abstract

To provide an optical laminate body with an improved resistance to impact and an improved adhesion.SOLUTION: The optical laminate body includes a phase difference film, an anchor layer, and an adhesive sheet. The optical laminate body has a structure in which the phase difference film, the anchor layer, and the adhesive sheet are laminated in this order. The phase difference film includes a polycarbonate resin. The anchor layer includes a polymer C. The anchor layer has a thickness of 15nm to 28nm, both inclusive. The polymer C may include at least one selected from the group of a polyoxy-alkylene group-containing polymer and a polyurethane polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical laminate, an image display device, and a method for manufacturing an optical laminate. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. These various image display devices typically have a laminated structure of an image-forming layer, such as a liquid crystal layer or an EL light-emitting layer, and an optical laminate including an optical film and a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet is mainly used for bonding between films included in the optical laminate, or for bonding between the image-forming layer and the optical laminate.

[0003] Patent Document 1 describes a polycarbonate resin laminate that includes a film layer containing at least a polycarbonate resin (A) and a substrate containing a polycarbonate resin (B) different from the polycarbonate resin (A), in which the film layer is a surface layer, and the polycarbonate resin-containing film layer satisfies certain conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-181785 Summary of the Invention [Problem to be solved by the invention]

[0005] The optical laminate includes, for example, an optical film such as a retardation film and an adhesive sheet. In the manufacturing process of an image display device, the optical laminate is sometimes positioned such that its side faces are aligned with alignment members such as rods and pins in order to be positioned at a predetermined position. In this case, contact with the alignment members may cause chipping of the adhesive at the edge of the optical laminate. The chipping of the adhesive can cause display defects in the image display device.

[0006] Therefore, an object of the present invention is to provide an optical laminate having improved impact resistance and adhesion. [Means for solving the problem]

[0007] The present invention provides An optical laminate comprising a retardation film containing a polycarbonate-based resin, an anchor layer containing polymer C, and a pressure-sensitive adhesive sheet, wherein the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order, The present invention provides an optical laminate, wherein the anchor layer has a thickness of 15 nm or more and 28 nm or less.

[0008] Furthermore, the present invention provides An image display device is provided, which includes the optical laminate and an image forming layer.

[0009] Furthermore, the present invention provides A method for producing an optical laminate comprising a retardation film containing a polycarbonate-based resin, an anchor layer containing polymer C, and a pressure-sensitive adhesive sheet, wherein the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order, applying an anchor layer coating solution containing a solvent S containing an organic solvent and a polymer C to the retardation film to form a coating film having a thickness of T (μm); and drying the coating film; In the anchor layer coating liquid, the weight ratio Wc of the polymer C to 100 weight parts of the solvent S is 0.01 or more and 0.5 or less, The method for producing an optical laminate is provided, wherein the equivalent thickness of the coating film calculated by the following formula (1) is 2 μm or more and 10 μm or less. Equivalent thickness of coating film = T × Wc / 0.1 (1) [Effects of the Invention]

[0010] According to the present invention, an optical layered body having improved impact resistance and adhesion can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of the optical laminate of the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of the optical laminate. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an example of the image display device of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The optical laminate according to the first aspect of the present invention is An optical laminate comprising a retardation film containing a polycarbonate-based resin, an anchor layer containing polymer C, and a pressure-sensitive adhesive sheet, wherein the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order, The anchor layer has a thickness of 15 nm or more and 28 nm or less.

[0013] In a second aspect of the present invention, for example, in the optical laminate according to the first aspect, the polymer C contains at least one selected from the group consisting of polyoxyalkylene group-containing polymers and polyurethane-based polymers.

[0014] In a third aspect of the present invention, for example, in the optical laminate according to the first or second aspect, the anchor layer has a thickness of 15 nm or more and 23 nm or less.

[0015] In a fourth aspect of the present invention, for example, in the optical layered body according to any one of the first to third aspects, the pressure-sensitive adhesive sheet has a storage modulus at 25° C. of 0.05 MPa or more.

[0016] In a fifth aspect of the present invention, for example, in the optical layered body according to any one of the first to fourth aspects, the pressure-sensitive adhesive sheet has a storage modulus at 25° C. of 0.15 MPa or more.

[0017] An image display device according to a sixth aspect of the present invention comprises the optical laminate according to any one of the first to fifth aspects and an image forming layer.

[0018] A method for producing an optical laminate according to a seventh aspect of the present invention includes: A method for producing an optical laminate comprising a retardation film containing a polycarbonate-based resin, an anchor layer containing polymer C, and a pressure-sensitive adhesive sheet, wherein the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order, applying an anchor layer coating solution containing a solvent S containing an organic solvent and a polymer C to the retardation film to form a coating film having a thickness of T (μm); and drying the coating film; In the anchor layer coating liquid, the weight ratio Wc of the polymer C to 100 weight parts of the solvent S is 0.01 or more and 0.5 or less, The equivalent thickness of the coating film calculated by the following formula (1) is 2 μm or more and 10 μm or less. Equivalent thickness of coating film = T × Wc / 0.1 (1)

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, but is not limited to the following embodiments.

[0020] The optical laminate according to this embodiment includes a retardation film, an anchor layer, and a pressure-sensitive adhesive sheet. The optical laminate has a structure in which the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order. The retardation film includes a polycarbonate resin. The anchor layer includes polymer C. The anchor layer has a thickness of 15 nm or more and 28 nm or less.

[0021] The formation of an anchor layer is a means that can achieve both chip prevention and adhesion of the pressure-sensitive adhesive sheet. However, according to the studies of the present inventors, it has been found that when an anchor layer is laminated on a retardation film containing a polycarbonate-based resin, a brittle layer is formed on the surface of the retardation film on which the anchor layer is formed. The brittle layer develops specifically when a retardation film containing a polycarbonate-based resin is used. Although the details are not clear, it is presumed that the brittle layer is formed when the organic solvent contained in the coating solution for forming the anchor layer partially reacts with or partially alters the polycarbonate-based resin contained in the retardation film. The formation of the brittle layer reduces the adhesion between the pressure-sensitive adhesive sheet and the retardation film, i.e., the anchoring force. As a result of further studies, it has been found that in order to prevent chipping of the pressure-sensitive adhesive sheet while mitigating the influence of the brittle layer, it is effective to form the anchor layer with an appropriate thickness.

[0022] 1 is a cross-sectional view schematically showing an example of an optical laminate of the present embodiment. The optical laminate 1A includes a retardation film 2, an anchor layer 3, and a pressure-sensitive adhesive sheet 4. The optical laminate 1A has a structure in which the retardation film 2, the anchor layer 3, and the pressure-sensitive adhesive sheet 4 are laminated in this order.

[0023] The anchor layer 3 is formed on the retardation film 2. The anchor layer 3 is in contact with the retardation film 2. The anchor layer 3 is formed on one main surface of the retardation film 2. In FIG. 1, the anchor layer 3 is formed on the entire one main surface of the retardation film 2. However, the anchor layer 3 may be formed on only a part of one main surface of the retardation film 2. In this specification, the "main surface" means the surface of a film or layer having the largest area.

[0024] The adhesive sheet 4 is formed in contact with the anchor layer 3. The adhesive sheet 4 is formed on one main surface of the anchor layer 3. Specifically, the adhesive sheet 4 is formed on the main surface of the anchor layer 3 on which the retardation film 2 is not formed. In FIG. 1 , the adhesive sheet 4 is formed on the entire one main surface of the anchor layer 3. However, the adhesive sheet 4 may be formed on only a part of the one main surface of the anchor layer 3.

[0025] [Adhesive sheet] The pressure-sensitive adhesive sheet is formed from, for example, the pressure-sensitive adhesive composition (I). Details of the pressure-sensitive adhesive composition (I) are described below.

[0026] [Adhesive composition (I)] Examples of adhesives that constitute the adhesive sheet include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine-based adhesives, epoxy adhesives, and polyether adhesives. The adhesives that constitute the adhesive sheet are used alone or in combination of two or more. However, from the viewpoints of transparency, processability, durability, adhesion, etc., it is preferable to use an acrylic adhesive (composition) containing a (meth)acrylic polymer alone. In other words, it is preferable that the adhesive sheet contains a (meth)acrylic polymer. In this specification, "(meth)acrylic" means acrylic and methacrylic. Furthermore, "(meth)acrylate" means acrylate and methacrylate.

[0027] [(Meth)acrylic polymer (A)] The (meth)acrylic polymer (A) may have, as a main unit, a structural unit derived from a (meth)acrylic monomer having an alkyl group having 1 to 30 carbon atoms on the side chain. The alkyl group may be linear or branched. The (meth)acrylic polymer (A) may have one or more structural units derived from a (meth)acrylic monomer (A1). Examples of the (meth)acrylic monomer (A1) include methyl (meth)acrylate, ethyl (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, and isoheptyl (meth)acrylate. acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate (lauryl(meth)acrylate), n-tridecyl(meth)acrylate, and n-tetradecyl(meth)acrylate. In this specification, the term "main unit" refers to a unit that accounts for, for example, 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, particularly preferably 80% by weight or more, and even more preferably 90% by weight or more of all the structural units contained in the polymer.

[0028] The (meth)acrylic polymer (A) may have a structural unit derived from a (meth)acrylic monomer (A1) which, when made into a homopolymer, has a glass transition temperature (Tg) in the range of −70 to −20° C. An example of the monomer (A1) is n-butyl acrylate.

[0029] The (meth)acrylic polymer (A) may contain a structural unit other than the structural unit derived from the (meth)acrylic monomer (A1). The structural unit is derived from a monomer (A2) copolymerizable with the (meth)acrylic monomer (A1). The (meth)acrylic polymer (A) may contain one or more types of such structural units.

[0030] An example of the monomer (A2) is an aromatic ring-containing monomer. The aromatic ring-containing monomer may be an aromatic ring-containing (meth)acrylic monomer. Examples of the aromatic ring-containing monomer include phenyl(meth)acrylate, phenoxyethyl(meth)acrylate, benzyl(meth)acrylate, phenoxydiethylene glycol(meth)acrylate, ethylene oxide-modified nonylphenol(meth)acrylate, hydroxyethylated β-naphthol(meth)acrylate, and biphenyl(meth)acrylate. The content of the structural unit derived from the aromatic ring-containing monomer in the (meth)acrylic polymer (A) is, for example, 0 to 50 wt%, or may be 1 to 30 wt%, 5 to 25 wt%, or even 8 to 20 wt%. Increasing the amount of the crosslinking agent (B) in the pressure-sensitive adhesive composition (I) may result in the formation of a self-polymer of the crosslinking agent (B). The presence of a structural unit derived from an aromatic ring-containing monomer in the (meth)acrylic polymer (A) improves the compatibility of the (meth)acrylic polymer (A) with the crosslinking agent (B) and its self-polymerization. Improved compatibility can contribute to improved uniformity of the PSA sheet, for example, by suppressing precipitation of the self-polymerization.

[0031] Another example of the monomer (A2) is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a hydroxyl group-containing (meth)acrylic monomer. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, as well as (4-hydroxymethylcyclohexyl)-methyl acrylate. The hydroxyl group can react with various crosslinking agents. From the viewpoint of increasing the uniformity of the crosslinked structure to be formed, the content of the structural unit derived from the hydroxyl group-containing monomer in the (meth)acrylic polymer (A) may be 1% by weight or less, 0.5% by weight or less, or even 0.1% by weight or less, or may even be 0% by weight (no such structural unit may be contained).

[0032] Monomer (A2) may be a carboxyl group-containing monomer, an amino group-containing monomer, or an amide group-containing monomer. Examples of the carboxyl group-containing monomer are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the amino group-containing monomer are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(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-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. The (meth)acrylic polymer (A) having a structural unit derived from a carboxyl group-containing monomer, particularly acrylic acid, can, for example, enhance the self-polymerization property of the crosslinking agent (B). The improved self-polymerization property of the crosslinking agent (B) can contribute to suppressing peeling of the PSA sheet, particularly in a humid environment, and stabilizing the physical properties of the PSA sheet in a system with a high content of the crosslinking agent (B).

[0033] Monomer (A2) may be a polyfunctional monomer. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. The polyfunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate.

[0034] The total content of structural units derived from carboxyl group-containing monomers, amino group-containing monomers, amide group-containing monomers, and polyfunctional monomers in the (meth)acrylic polymer (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 8% by weight or less. When the (meth)acrylic polymer (A) contains these structural units, the total content is, for example, 0.01% by weight or more, and may be 0.05% by weight or more. The (meth)acrylic polymer (A) does not necessarily have to contain structural units derived from polyfunctional monomers.

[0035] Examples of other monomers (A2) include (meth)acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; vinyl sulfonate; (meth)acrylic acid esters having an alicyclic hydrocarbon group, such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; vinyl esters, such as vinyl acetate and vinyl propionate; aromatic vinyl compounds, such as styrene and vinyl toluene; olefins or dienes, such as ethylene, propylene, butadiene, isoprene, and isobutylene; vinyl ethers, such as vinyl alkyl ether; and vinyl chloride.

[0036] The total content of the structural units derived from the other monomers (A2) in the (meth)acrylic polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, or may be 0% by weight (not including the structural units).

[0037] The (meth)acrylic polymer (A) can be formed by polymerizing one or more of the above-mentioned monomers by a known method. A monomer and a partial polymer of the monomer may also be polymerized. The polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. Solution polymerization and active energy ray polymerization are preferred because they allow the formation of a pressure-sensitive adhesive sheet with excellent optical transparency. The polymerization is preferably carried out while avoiding contact between the monomer and / or the partial polymer and oxygen. For this purpose, for example, polymerization in an inert gas atmosphere such as nitrogen, or polymerization in a state where oxygen is blocked by a resin film or the like, can be employed. The (meth)acrylic polymer (A) formed may be in any form, such as a random copolymer, a block copolymer, or a graft copolymer.

[0038] The polymerization system for forming the (meth)acrylic polymer (A) may contain one or more polymerization initiators. The type of polymerization initiator can be selected depending on the polymerization reaction, and may be, for example, a thermal polymerization initiator or a photopolymerization initiator.

[0039] Examples of solvents used in solution polymerization include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

[0040] Examples of polymerization initiators used in solution polymerization include azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Examples of peroxide polymerization initiators include dibenzoyl peroxide and t-butyl permaleate. Among these, the azo polymerization initiators disclosed in JP-A-2002-69411 are preferred. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, or may be 0.1 to 0.3 parts by weight, per 100 parts by weight of the total amount of monomers.

[0041] The active energy rays used in the active energy ray polymerization include, for example, ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams, as well as ultraviolet rays. The active energy ray is preferably ultraviolet rays. Polymerization by irradiation with ultraviolet rays is also called photopolymerization. The polymerization system for the active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for the active energy polymerization are not limited as long as a (meth)acrylic polymer (A) is formed.

[0042] Examples of the photopolymerization initiator include a benzoin ether-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, an aromatic sulfonyl chloride-based photopolymerization initiator, a photoactive oxime-based photopolymerization initiator, a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator, although the photopolymerization initiator is not limited to the above examples.

[0043] Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. An example of a photoactive oxime-based photopolymerization initiator is 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. An example of a benzoin-based photopolymerization initiator is benzoin. An example of a benzyl-based photopolymerization initiator is benzil. An example of a benzophenone-based photopolymerization initiator is benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, or α-hydroxycyclohexyl phenyl ketone. An example of a ketal-based photopolymerization initiator is benzil dimethyl ketal. An example of a thioxanthone-based photopolymerization initiator is thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, or dodecylthioxanthone.

[0044] The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

[0045] The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) is, for example, 1,000,000 to 2,800,000, and from the viewpoint of the durability and heat resistance of the PSA sheet, may be 1,200,000 or more, or even 1,400,000 or more. The weight average molecular weight (Mw) of the polymer and oligomer in this specification is a value (polystyrene equivalent) based on measurement by GPC (gel permeation chromatography).

[0046] The content of the (meth)acrylic polymer (A) in the pressure-sensitive adhesive composition (I) may be, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, or even 85% by weight or more, in terms of solid content. The upper limit of the content may be, for example, 99.5% by weight, 99% by weight, 97% by weight, 95% by weight, 93% by weight, or even 90% by weight.

[0047] [Crosslinking agent (B)] The crosslinking agent (B) is typically a polyfunctional crosslinking agent having two or more crosslinking reactive groups per molecule. The crosslinking agent (B) may also be a trifunctional or higher crosslinking agent having three or more crosslinking reactive groups per molecule. The upper limit of the number of crosslinking reactive groups per molecule is, for example, five.

[0048] The crosslinking agent (B) is, for example, an isocyanate-based crosslinking agent. The isocyanate-based crosslinking agent contains an isocyanate group as a crosslinking reactive group. The isocyanate-based crosslinking agent (B) may be an aromatic isocyanate compound, an alicyclic isocyanate compound, or an aliphatic isocyanate compound. An isocyanate-based crosslinking agent (particularly a trifunctional isocyanate-based crosslinking agent) is preferred in terms of durability.

[0049] Examples of aromatic isocyanate compounds that can be used in the crosslinking agent (B) 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.

[0050] Examples of the alicyclic isocyanate compound that can be used in the crosslinking agent (B) 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.

[0051] Examples of aliphatic isocyanate compounds that can be used in the crosslinking agent (B) are trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0052] The crosslinking agent (B) may be a derivative of the isocyanate compound. Examples of the derivative include multimers (dimers, trimers, pentamers, etc.), adducts obtained by addition 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 addition to polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.

[0053] The crosslinking agent (B) is preferably an aromatic isocyanate compound or a derivative thereof, more preferably tolylene diisocyanate or a derivative thereof (i.e., a tolylene diisocyanate (TDI) crosslinking agent). TDI crosslinking agents have better reaction uniformity than xylylene diisocyanate or a derivative thereof (i.e., a xylylene diisocyanate (XDI) crosslinking agent). An example of a TDI crosslinking agent is an adduct of tolylene diisocyanate and a polyfunctional alcohol, and a more specific example is a trimethylolpropane / tolylene diisocyanate trimer adduct.

[0054] Commercially available products can be used for the crosslinking agent (B). Examples of commercially available products include Millionate MT, Millionate MTL, Millionate MR-200, Millionate MR-400, Coronate L, Coronate HL, and Coronate HX (all manufactured by Tosoh Corporation; all trade names), as well as Takenate D-101E, Takenate D-102, Takenate D-103, Takenate D-110N, Takenate D-120N, Takenate D-140N, Takenate D-160N, Takenate D-165N, Takenate D-170HN, Takenate D-178N, Takenate 500, and Takenate 600 (all manufactured by Mitsui Chemicals, Inc.; all trade names). Takenate D-101E is preferably used for the crosslinking agent (B).

[0055] The isocyanate-based crosslinking agent may be used alone or in combination of two or more. The amount of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition (I) may be, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, or even 2.3 parts by weight or more, per 100 parts by weight of the (meth)acrylic polymer (A). The upper limit of the amount may be, for example, 30 parts by weight or less, 28 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, or even 3 parts by weight or less.

[0056] The pressure-sensitive adhesive composition (I) may contain a crosslinking agent other than an isocyanate-based crosslinking agent. Examples of crosslinking agents other than an isocyanate-based crosslinking agent include peroxide-based crosslinking agents, epoxy-based crosslinking agents, imine-based crosslinking agents, and polyfunctional metal chelates. The amount of the crosslinking agent other than an isocyanate-based crosslinking agent may be, for example, 2 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.28 parts by weight or less, 0.25 parts by weight or less, 0.2 parts by weight or less, or even 0.15 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer (A). The lower limit of the amount is, for example, 0 parts by weight. The crosslinking agent (B) may contain an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent. From the viewpoint of durability of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition (I) may be substantially free of other crosslinking agents, particularly epoxy-based crosslinking agents.

[0057] [Additives] The pressure-sensitive adhesive composition (I) may contain other additives. Examples of additives include silane coupling agents, polyfunctional alcohols, colorants such as pigments and dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, softeners, antioxidants, antiaging agents, light stabilizers, UV absorbers, polymerization inhibitors, antistatic agents (such as alkali metal salts, ionic liquids, and ionic solids, which are ionic compounds), inorganic fillers, organic fillers, powders such as metal powders, particles, and foil-like materials. The additives can be blended in an amount of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, and more preferably 1.5 parts by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0058] Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

[0059] When the pressure-sensitive adhesive composition (I) contains a silane coupling agent, the blending amount thereof is, for example, 5 parts by weight or less, and may be 3 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, or even 0.05 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer (A). The pressure-sensitive adhesive composition (I) does not necessarily contain a silane coupling agent.

[0060] The pressure-sensitive adhesive composition (I) may contain a polyfunctional alcohol. The molecular weight of the polyfunctional alcohol is, for example, 240 or less, and may be 230 or less, 220 or less, 210 or less, 200 or less, 190 or less, 180 or less, 170 or less, 160 or less, or even 150 or less. The lower limit of the molecular weight is, for example, 60 or more, 80 or more, 90 or more, or even 100 or more.

[0061] Examples of polyfunctional alcohols include alkylene glycols such as ethylene glycol and propylene glycol and polymers thereof, ether glycols such as diethylene glycol and polymers thereof, trimethylolethane, trimethylolpropane, glycerin, and sugar alcohols such as pentaerythritol and sorbitol. The polyfunctional alcohol is preferably trimethylolpropane, glycerin, or diethylene glycol and polymers thereof, more preferably trimethylolpropane.

[0062] The polyfunctional alcohol may be trifunctional or higher. Examples of trifunctional polyfunctional alcohols are trimethylolpropane and glycerin.

[0063] The polyfunctional alcohol may have a reactive group other than the hydroxyl group that is reactive with the crosslinking agent (B). The reactive group is, for example, at least one selected from an amino group, a carboxyl group, and an epoxy group, and is particularly an amino group.

[0064] The amount of the polyfunctional alcohol in the pressure-sensitive adhesive composition (I) is, for example, 0.5 to 20 parts by weight per 100 parts by weight of the (meth)acrylic polymer (A), and the upper limit of the amount may be 15 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, or even 3 parts by weight or less.

[0065] The pressure-sensitive adhesive composition (I) may not contain a crosslinking accelerator such as a catalyst. Examples of crosslinking accelerators include polyethers, polyether polyols, and phosphate esters having a reactive group reactive with the crosslinking agent (B). The reactive group is, for example, at least one selected from a hydroxyl group, an amino group, a carboxyl group, and an epoxy group, and is particularly a hydroxyl group or an amino group. The pressure-sensitive adhesive composition (I) may not contain a polyether polyol having an amino group, or a phosphate ester having a hydroxyl group.

[0066] The pressure-sensitive adhesive composition (I) may be, for example, an emulsion type, a solvent type (solution type), an active energy ray curable type (photocurable type), or a hot melt type (hot melt type). From the viewpoint of forming a pressure-sensitive adhesive sheet with superior durability, the pressure-sensitive adhesive composition (I) may be a solvent type. The solvent-type pressure-sensitive adhesive composition (I) may not contain a photocuring agent such as an ultraviolet curing agent.

[0067] [Manufacturing method of adhesive sheet] The pressure-sensitive adhesive sheet 4 is formed from the pressure-sensitive adhesive composition (I). The pressure-sensitive adhesive sheet 4 contains, for example, a crosslinked product of the (meth)acrylic polymer (A). The pressure-sensitive adhesive sheet 4 can be formed from the pressure-sensitive adhesive composition (I) by the following method.

[0068] The method for producing the pressure-sensitive adhesive sheet 4 includes, for example, applying a pressure-sensitive adhesive composition (I) containing a (meth)acrylic polymer (A) and a crosslinking agent to a substrate to form a coating film, and drying the resulting coating film.

[0069] The substrate can be, for example, a release film. The pressure-sensitive adhesive sheet 4 formed on the release film can be transferred to, for example, an optical film. The substrate may be an optical film. In this case, the first pressure-sensitive adhesive sheet can be formed on the optical film, and an optical film with the first pressure-sensitive adhesive sheet can be obtained.

[0070] After the adhesive sheet 4 is transferred to the anchor layer 3, the release film can be used as a separator until the adhesive sheet 4 is put to practical use, thereby simplifying the process.

[0071] Examples of materials constituting the release film include suitable thin sheets such as porous materials such as plastic film, paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof, but plastic film is preferably used because of its excellent surface smoothness.

[0072] The plastic film is not particularly limited, and examples thereof include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, and ethylene-vinyl acetate copolymer film.

[0073] The thickness of the release film is usually 5 to 200 μm, and preferably about 5 to 100 μm. The release film is subjected to a release treatment such as a silicone-based, fluorine-based, or long-chain alkyl-based treatment. The release film may be subjected to a release and antifouling treatment using a fatty acid amide-based release agent, silica powder, or the like, or an antistatic treatment such as a coating-type, kneading-type, or vapor deposition-type.

[0074] A solution (adhesive solution) containing the adhesive composition (I) may be applied to the substrate. The solid content of the adhesive solution is, for example, 5 to 50 wt %, and preferably 10 to 40 wt %. The adhesive solution can be prepared by appropriately adding the same solvent as the polymerization solvent or a different solvent to the adhesive composition (I) depending on the polymerization form of the (meth)acrylic polymer (A).

[0075] Various methods can be used to apply the pressure-sensitive adhesive composition (I) to a substrate, including, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater, etc. The amount of pressure-sensitive adhesive composition (I) to be applied can be adjusted appropriately depending on the desired thickness of the pressure-sensitive adhesive sheet 4.

[0076] The coating film is dried to harden it and form the adhesive sheet 4. The drying temperature for the coating film is not particularly limited and is, for example, 130°C or lower, preferably 125°C or lower, more preferably 120°C or lower, even more preferably 110°C or lower, and particularly preferably 100°C or lower. The drying temperature for the coating film may be 60°C or higher, or may be 80°C or higher. When the drying temperature is 60°C or higher, for example, the reaction of the isocyanate-based crosslinking agent proceeds smoothly, the cohesive strength of the adhesive sheet 4 can be improved, and display unevenness of the image display device tends to be reduced. When the drying temperature is 130°C or lower, for example, the reaction rate of the isocyanate-based crosslinking agent can be appropriately adjusted, and transparency tends to be ensured.

[0077] The drying time of the coating film can be adjusted appropriately depending on the composition of the pressure-sensitive adhesive composition (I), and is preferably 30 to 300 seconds, more preferably 40 to 240 seconds, and particularly preferably 60 to 180 seconds.

[0078] The thickness of the pressure-sensitive adhesive sheet 4 is not particularly limited and may be 2 to 150 μm, 2 to 100 μm, or 5 to 50 μm. By appropriately adjusting the thickness of the pressure-sensitive adhesive sheet 4, it is possible to improve the adhesion between the retardation film 2 and the pressure-sensitive adhesive sheet 4. In addition, by appropriately adjusting the thickness of the pressure-sensitive adhesive sheet 4, it is possible to prevent the pressure-sensitive adhesive sheet 4 from peeling off from an adherend such as glass or an image display device.

[0079] The storage modulus G' of the pressure-sensitive adhesive sheet 4 at 25°C may be 0.05 MPa or more, 0.08 MPa or more, 0.10 MPa or more, 0.12 MPa or more, 0.13 MPa or more, or even 0.15 MPa or more. The upper limit of the storage modulus G' of the pressure-sensitive adhesive sheet 4 at 25°C may be 5 MPa or less, 4 MPa or less, 3 MPa or less, 2 MPa or less, 1 MPa or less, 0.5 MPa or less, 0.3 MPa or less, 0.25 MPa, or even 0.20 MPa or less.

[0080] A high storage modulus G' is suitable for suppressing shrinkage of the PSA sheet when heated, known as thermal unevenness. However, an excessively high storage modulus G' can cause a decrease in adhesion between the PSA and the substrate.

[0081] Anchor layer The anchor layer 3 containing the polymer C can be formed from an anchor layer coating liquid. The anchor layer coating liquid contains the polymer C and a solvent S containing an organic solvent.

[0082] (Solvent S containing organic solvent) The solvent S includes an organic solvent. The solvent S may be an organic solvent or a mixed solvent of an organic solvent and water. The organic solvent may be a polar organic solvent such as alcohol. The solvent S may contain water and alcohol. The solvent S may be a mixed solvent containing 65% to less than 100% by weight of water and more than 0% to 35% by weight of alcohol, or a mixed solvent containing 0% to 35% by weight of water and 65% to 100% by weight of alcohol. By appropriately adjusting the water and alcohol contents in the mixed solvent, the dispersion stability of the solute contained in the anchor layer coating liquid can be improved, thereby suppressing the generation of foreign matter in the anchor layer. In particular, a mixed solvent containing 65% to less than 100% by weight of water and more than 0% to 35% by weight of alcohol (hereinafter referred to as a "water-rich mixed solvent") can sufficiently improve the dispersibility of polythiophene-based polymers, which have conductivity suitable as binder components. As a result, the conductive performance of the anchor layer obtained after coating and drying the anchor layer coating liquid is further improved.

[0083] On the other hand, when a mixed solvent containing 0% by weight or more and 35% by weight or less of water and 65% by weight or more and 100% by weight or less of alcohol (hereinafter referred to as an "alcohol-rich mixed solvent") is used, the compatibility of the anchor layer coating liquid, the wettability to the retardation film, the adhesion between the retardation film and the anchor layer, and the coating appearance of the anchor layer can be further improved.

[0084] The alcohol may be miscible with water in any ratio at room temperature (25°C). The alcohol may be an alcohol having 1 to 6 carbon atoms, an alcohol having 1 to 4 carbon atoms, or an alcohol having 1 to 3 carbon atoms. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropyl alcohol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol. Ethanol and isopropyl alcohol are preferred, and isopropyl alcohol is more preferred. The alcohol may be used alone or in combination of two or more selected from the above compounds. Two or more alcohols may be mixed in any ratio. For example, a mixed alcohol obtained by mixing ethanol and isopropanol in any ratio may be used as the alcohol.

[0085] Solvent S may contain a mixed solvent of water and alcohol as a main component. This can further improve the optical properties of the optical film. In addition, by containing a mixed solvent of water and alcohol as a main component, the durability of the optical laminate in high-temperature and high-humidity environments can be further improved. In this specification, "main component" means the component that is contained in the largest amount by weight. The total amount of water and alcohol contained in solvent S may be 90% by weight or more, 95% by weight or more, 99% by weight or more, or even 100% by weight.

[0086] (Polymer C) The anchor layer coating liquid contains polymer C. Polymer C may contain at least one selected from the group consisting of polyoxyalkylene group-containing polymers and polyurethane polymers. These polymers are described in detail below.

[0087] (Polyoxyalkylene group-containing polymer) An example of the polyoxyalkylene group-containing polymer is a polyoxyalkylene group-containing poly(meth)acrylate. The polyoxyalkylene group-containing poly(meth)acrylate has a structure in which the main chain is a poly(meth)acrylate polymer and the side chain contains polyoxyalkylene groups such as polyoxyethylene groups and polyoxypropylene groups. The polyoxyalkylene group-containing polymer may be a polyoxyethylene group-containing poly(meth)acrylate.

[0088] In the anchor layer coating liquid, the weight ratio of the polyoxyalkylene group-containing polymer to 100 weight parts of the solvent S may be 0.005 to 5, 0.01 to 3, 0.01 to 1, or 0.01 to 0.5.

[0089] (Polyurethane polymer) Examples of polyurethane-based polymers include water-soluble polyurethane resin-based binders and water-dispersible polyurethane resin-based binders. In this specification, "water-soluble" means that the solubility of the solute in 100 g of water is 5 g or more.

[0090] The polyurethane polymer can contribute to improving the anchoring power of the pressure-sensitive adhesive sheet, for example. In particular, when the polymer C contains a polyurethane polymer, the adhesion between the retardation film 2 and the pressure-sensitive adhesive sheet 4 can be improved.

[0091] In the anchor layer coating liquid, the weight ratio of the polyurethane polymer to 100 weight parts of the solvent S may be 0.005 to 5, 0.01 to 3, 0.01 to 1, or 0.01 to 0.5.

[0092] (Oxazoline group-containing polymer) Polymer C may contain an oxazoline group-containing polymer. The oxazoline group-containing polymer has a main chain composed of an acrylic skeleton or a styrene skeleton. In addition, the oxazoline group-containing polymer has oxazoline groups on side chains. The oxazoline group-containing polymer may be an oxazoline group-containing acrylic polymer that has a main chain composed of an acrylic skeleton and has oxazoline groups on side chains of the main chain.

[0093] Examples of the oxazoline group are a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. The oxazoline group may be a 2-oxazoline group.

[0094] The number average molecular weight of the oxazoline group-containing polymer may be 5,000 or more, or may be 10,000 or more. The upper limit of the number average molecular weight of the oxazoline group-containing polymer is not particularly limited, and is, for example, 1,000,000. By appropriately adjusting the number average molecular weight of the oxazoline group-containing polymer, the anchor layer can have the desired strength.

[0095] The oxazoline value of the oxazoline group-containing polymer may be 1500 g solid / eq. or less, 1200 g solid / eq. or less, 1000 g solid / eq. or less, 500 g solid / eq. or less, or 300 g solid / eq. or less. The oxazoline group reacts with functional groups such as carboxyl groups and hydroxyl groups contained in the pressure-sensitive adhesive composition (I) at relatively low temperatures. Therefore, by including an oxazoline group-containing polymer in the anchor layer, the adhesion between the anchor layer and the pressure-sensitive adhesive sheet can be improved.

[0096] Examples of the oxazoline group-containing polymer are oxazoline group-containing acrylic polymers and oxazoline group-containing acrylic / styrene polymers. Examples of the oxazoline group-containing acrylic polymer are EPOCROS WS-300, EPOCROS WS-500, and EPOCROS WS-700 manufactured by Nippon Shokubai Co., Ltd. Examples of the oxazoline group-containing acrylic / styrene polymer are EPOCROS K-1000 series and EPOCROS K-2000 series manufactured by Nippon Shokubai Co., Ltd. The oxazoline group-containing polymer may be used alone or in combination of two or more selected from the above polymers.

[0097] (Other polymers) Polymer C may contain other polymers such as epoxy resin binders, isocyanate resin binders, and polyester resin binders. In addition, Polymer C may contain resins (polymers) having organic reactive groups, such as polymers containing amino groups in the molecule and acrylic resin binders containing oxazoline groups or the like.

[0098] (Polythiophene-based polymer) Polymer C may further contain a polythiophene-based polymer to improve the conductive performance of the anchor layer and the optical properties of the optical laminate.

[0099] Examples of polythiophene-based polymers include water-soluble polythiophene-based polymers and water-dispersible polythiophene-based polymers. The weight-average molecular weight of the polythiophene-based polymer, calculated as polystyrene, may be 400,000 or less, or may be 300,000 or less. By appropriately adjusting the weight-average molecular weight, the polythiophene-based polymer can be water-soluble or water-dispersible. By preparing an anchor layer coating solution using a water-soluble polythiophene-based polymer or a water-dispersible polythiophene-based polymer, the anchor layer coating solution can have an appropriate viscosity, making it possible to form an anchor layer with a uniform film thickness.

[0100] The solubility of the water-soluble polythiophene-based polymer in 100 g of water may be 20 to 30 g.

[0101] A water-dispersible polythiophene polymer refers to a polythiophene polymer dispersed in water in the form of fine particles. A water dispersion containing a water-dispersible polythiophene polymer can have low viscosity, making it easy to apply the anchor layer coating solution to a substrate. Additionally, the use of such a water dispersion allows the anchor layer to have a uniform film thickness. The size of the fine particles is not limited to a specific value, and is, for example, 1 μm or less.

[0102] The water-soluble polythiophene-based polymer and the water-dispersible polythiophene-based polymer may have a hydrophilic functional group in the molecule. Examples of the hydrophilic functional group include a sulfone group, an amino group, an amide group, an imino group, a quaternary ammonium base, a hydroxyl group, a mercapto group, a hydrazino group, a carboxyl group, a sulfate ester group, a phosphate ester group, and salts thereof. The presence of a hydrophilic functional group in the molecule improves the solubility in water and makes it easier to disperse in water in the form of fine particles. In addition, the presence of a hydrophilic functional group in the molecule makes it easier to prepare a water-soluble polythiophene-based polymer and a water-dispersible polythiophene-based polymer.

[0103] A specific example of the water-soluble polythiophene-based polymer and the water-dispersible polythiophene-based polymer is Denatron P-580W manufactured by Nagase Chemtec Corporation.

[0104] In the anchor layer coating solution, the weight ratio Wc of polymer C to 100 weight parts of solvent S may be 0.01 to 0.5, 0.03 to 0.3, 0.05 to 0.2, or 0.08 to 0.15. By appropriately adjusting Wc, the thickness of the anchor layer can be appropriately adjusted and the decrease in adhesion between the polycarbonate resin-containing retardation film and the anchor layer can be suppressed. In this specification, Wc may be referred to as the base concentration.

[0105] The anchor layer coating solution may contain additives as needed. Examples of additives include leveling agents, antifoaming agents, thickeners, antioxidants, etc. The proportion of these additives may usually be about 0.01 to 500 parts by weight, 0.1 to 300 parts by weight, or 1 to 100 parts by weight, per 100 parts by weight of polymer C.

[0106] The anchor layer 3 can be formed, for example, by applying an anchor layer coating liquid to a retardation film and drying it. Details of a method for producing the anchor layer 3 will be described later. The anchor layer 3 contains a polymer C. The polymer C may contain at least one selected from the group consisting of a polyoxyalkylene group-containing polymer and a polyurethane-based polymer.

[0107] The thickness of the anchor layer 3 is 15 nm or more and 28 nm or less. This makes it possible to obtain an optical laminate 1 with improved adhesion and impact resistance. The thickness of the anchor layer 3 may be 16 nm or more, or 17 nm or more. The upper limit of the thickness of the anchor layer 3 may be 27 nm or less, 26 nm or less, 25 nm or less, 24 nm or less, 23.5 nm or less, 23 nm, or even 22.5 nm or less. The thickness of the anchor layer 3 can be specified by its average thickness. The average thickness of the anchor layer can be measured by the method described in the Examples section.

[0108] [Retardation film] The retardation film contains a polycarbonate-based resin. The retardation film is, for example, composed of a stretched resin film. The retardation film may contain a polycarbonate-based resin as a main component. The content of the polycarbonate-based resin in the retardation film is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 80% by weight or more, or even 85% by weight or more. The upper limit of the content may be 99.5% by weight or less, 99% by weight or less, 97% by weight or less, 95% by weight or less, 93% by weight or less, or even 90% by weight or less. The retardation film may contain only a polycarbonate-based resin as a resin.

[0109] The polycarbonate resin has carbonate bonds that bond structural units together. The polycarbonate resin may have ester bonds in addition to carbonate bonds as bonds between structural units. In other words, the polycarbonate resin may contain a polyester carbonate resin.

[0110] The polycarbonate-based resin may contain at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and structural units represented by the following general formula (2). These structural units are structural units derived from divalent oligofluorene, and may be referred to as oligofluorene structural units hereinafter. Such polycarbonate-based resins and the like have positive refractive index anisotropy.

[0111] [ka]

[0112] [ka]

[0113] <Oligofluorene structural unit> The oligofluorene structural unit is represented by the above general formula (1) or (2). In general formulas (1) and (2), R 1 ~R 3 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group, provided that R 4 ~R 9 may be the same or different, and R 4 ~R 9 At least two adjacent groups among these may be bonded to each other to form a ring.

[0114] The content of the oligofluorene structural unit in the polycarbonate resin may be 1 wt % to 40 wt %, 10 wt % to 35 wt %, 15 wt % to 30 wt %, or 18 wt % to 25 wt % based on the total resin. By appropriately adjusting the content of the oligofluorene structural unit, the absolute value of the photoelastic coefficient can be adjusted to a desired range, reliability can be improved, and retardation expression can be improved. By appropriately adjusting the content of the oligofluorene structural unit, a retardation film having desired properties can be produced.

[0115] <Other structural units> The polycarbonate resin may contain other structural units in addition to the oligofluorene structural unit. Examples of the other structural units may be derived from dihydroxy compounds or diester compounds. For example, in order to exhibit reverse dispersion wavelength properties, it is necessary to incorporate a structural unit having positive intrinsic birefringence into the polymer structure together with an oligofluorene structural unit having negative intrinsic birefringence. Therefore, the other structural unit (monomer) to be copolymerized may be a dihydroxy compound or diester compound that is a raw material for the structural unit having positive birefringence.

[0116] Examples of copolymerizable monomers include compounds into which a structural unit containing an aromatic ring can be introduced, and compounds into which a structural unit containing an aromatic ring cannot be introduced, that is, compounds constituted by an aliphatic structure.

[0117] Examples of compounds having an aliphatic structure include dihydroxy compounds of straight-chain aliphatic hydrocarbons, dihydroxy compounds of branched aliphatic hydrocarbons, secondary alcohols of alicyclic hydrocarbons, tertiary alcohols of alicyclic hydrocarbons, primary alcohols of alicyclic hydrocarbons, oxyalkylene glycols, dihydroxy compounds having a cyclic ether structure, dihydroxy compounds having a cyclic acetal structure, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids. Specific examples of dihydroxy compounds of straight-chain aliphatic hydrocarbons include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. Specific examples of dihydroxy compounds of branched aliphatic hydrocarbons include neopentyl glycol and hexylene glycol. Specific examples of secondary alicyclic hydrocarbon alcohols include 1,2-cyclohexanediol, 1,4-cyclohexanediol, and hydrogenated bisphenol A. Specific examples of tertiary alicyclic hydrocarbon alcohols include 1,3-adamantanediol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Specific examples of primary alicyclic hydrocarbon alcohols include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecanedimethanol, 2,6-decalindimethanol, 1,5-decalindimethanol, 2,3-decalindimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, and 1,3-adamantanedimethanol. Another specific example of primary alicyclic hydrocarbon alcohols is a dihydroxy compound derived from a terpene compound, such as limonene. Specific examples of oxyalkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and polypropylene glycol. A specific example of a dihydroxy compound having a cyclic ether structure is isosorbide. Specific examples of a dihydroxy compound having a cyclic acetal structure are spiroglycol and dioxane glycol.Specific examples of alicyclic dicarboxylic acids are 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.Specific examples of aliphatic dicarboxylic acids are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0118] Examples of compounds that can introduce a structural unit containing an aromatic ring include aromatic bisphenol compounds, dihydroxy compounds having an ether group bonded to an aromatic group, and aromatic dicarboxylic acids. Specific examples of aromatic bisphenol compounds include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis( bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenyl ether, and 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether.Specific examples of dihydroxy compounds having an ether group bonded to an aromatic group include 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, and bis(4-(2-hydroxyethoxy)phenyl)sulfone. Specific examples of aromatic dicarboxylic acids include terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid.

[0119] The above-described aliphatic dicarboxylic acids and aromatic dicarboxylic acids can be used as raw materials for polyester carbonate resins as dicarboxylic acids themselves, but depending on the production method, dicarboxylic acid esters such as methyl esters and phenyl esters, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

[0120] As a copolymerization monomer, a compound known as a compound having a structural unit with negative birefringence may be used in combination with an oligofluorene compound.Examples of such compounds are dihydroxy compounds having a fluorene ring and dicarboxylic acid compounds having a fluorene ring.Examples of dihydroxy compounds having a fluorene ring are 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene.

[0121] The polycarbonate resin may contain a structural unit represented by the following formula (3) as a copolymerization component, among structural units that can be introduced by a compound having an alicyclic structure.

[0122] [ka]

[0123] An example of a dihydroxy compound into which the structural unit represented by formula (3) can be introduced is spiroglycol.

[0124] In the polycarbonate resin, the content of the structural unit represented by formula (3) may be 5% by weight or more and 90% by weight or less. The upper limit of the content may be 70% by weight or 50% by weight. The lower limit of the content may be 10% by weight, 20% by weight, or 25% by weight. When the content of the structural unit represented by formula (3) is 5% by weight or more, it is possible to improve mechanical properties and heat resistance, and to obtain a low photoelastic coefficient. Furthermore, compatibility with acrylic resins is improved, and the transparency of the resulting resin composition can be further improved. Furthermore, when the content is 90% by weight or less, the polymerization reaction of the spiro glycol is relatively slow, making it easier to control the polymerization reaction.

[0125] The polycarbonate resin may further contain a structural unit represented by the following formula (4) as a copolymerization component.

[0126] [ka]

[0127] Dihydroxy compounds capable of introducing the structural unit represented by formula (4) include isosorbide (ISB), isomannide, and isoidet, which are stereoisomers. These may be used alone or in combination of two or more.

[0128] In the polycarbonate resin, the content of the structural unit represented by formula (4) may be 5% by weight or more and 90% by weight or less. The upper limit of the content may be 70% by weight or less, or 50% by weight or less. The lower limit of the content may be 10% by weight or more, or 15% by weight or more. By appropriately adjusting the content of the structural unit represented by formula (4), it is possible to improve mechanical properties and heat resistance, and to obtain a low photoelastic coefficient. In addition, by appropriately adjusting the content of the structural unit represented by formula (4), it is possible to suppress dimensional changes of the molded body due to water absorption by the resin within an acceptable range.

[0129] The polycarbonate resin may further contain other structural units. Such structural units are referred to as "other structural units." Monomers having other structural units include 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, and 1,4-cyclohexanedicarboxylic acid, as well as derivatives thereof. The other structural units may be 1,4-cyclohexanedimethanol and tricyclodecane dimethanol. Resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, and the like. Note that, since the polymerization reactivity of diester compounds is relatively low, diester compounds other than diester compounds containing oligofluorene structural units may not be used in order to increase reaction efficiency.

[0130] The glass transition temperature (Tg) of the polycarbonate-based resin is, for example, 110°C or higher and 160°C or lower. The glass transition temperature may be 155°C or lower, 150°C or lower, or even 145°C or lower. The glass transition temperature may be 120°C or higher, or 130°C or higher. When the glass transition temperature is within the above range, the heat resistance of the polycarbonate-based resin can be improved. As a result, dimensional change when the film is molded can be suppressed, and the quality reliability of the optical laminate under use conditions can be improved. In addition, when the glass transition temperature is within the above range, stretchability and transparency can be improved.

[0131] Details of the oligofluorene structural unit, as well as the structure and production method of the polycarbonate resin, are described in, for example, WO 2015 / 159928.

[0132] <Acrylic resin> The retardation film may further contain an acrylic resin, the content of which is, for example, 0.5% by weight to 1.5% by weight.

[0133] As the acrylic resin, an acrylic resin as a thermoplastic resin is used. Examples of monomers that form the structural units of the acrylic resin include the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate. Acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, cyclopentyl methacrylate, cyclopentyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, cycloheptyl methacrylate, cycloheptyl acrylate, cyclooctyl methacrylate, cyclooctyl acrylate, cyclododecyl methacrylate, and cyclododecyl acrylate. These may be used alone or in combination of two or more. Examples of the use of a combination of two or more monomers include copolymerization of two or more monomers, blends of two or more homopolymers of one monomer, and combinations thereof. Furthermore, other monomers copolymerizable with these acrylic monomers (e.g., olefinic monomers, vinylic monomers) may be used in combination.

[0134] The acrylic resin contains a structural unit derived from methyl methacrylate. The content of the structural unit derived from methyl methacrylate in the acrylic resin may be 70% by mass or more and 100% by mass or less. The content may be 80% by mass or more, 90% by mass or more, or even 95% by mass or more. Within this range, excellent compatibility with the polycarbonate resin of the present invention is obtained. As structural units other than methyl methacrylate, methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene are preferably used. Copolymerization of methyl acrylate can improve thermal stability. The refractive index of the acrylic resin can be adjusted by using phenyl (meth)acrylate, benzyl (meth)acrylate, or styrene. Therefore, by matching the refractive index to that of the resin to be combined, the transparency of the resulting resin composition can be improved. By using such an acrylic resin, a reverse dispersion retardation film with excellent stretchability and retardation expression and low haze can be obtained.

[0135] The weight-average molecular weight Mw of the acrylic resin is, for example, 10,000 or more and 200,000 or less. The weight-average molecular weight may be 30,000 or more, or 50,000 or more. The weight-average molecular weight may be 180,000 or less, or 150,000 or less. When the weight-average molecular weight is within this range, compatibility with the polycarbonate resin is obtained. As a result, the transparency of the final retardation film can be improved, and the stretchability during stretching can be sufficiently improved. The weight-average molecular weight of the acrylic resin is the molecular weight measured by GPC in terms of polystyrene. From the viewpoint of compatibility, it is preferable that the acrylic resin does not substantially contain a branched structure. The absence of a branched structure can be confirmed by the GPC curve of the acrylic resin being unimodal.

[0136] As described above, the retardation film is composed of, for example, a stretched film of a resin film. The retardation film satisfies, for example, Re(450) < Re(550). The retardation film may further satisfy Re(550) < Re(650). The retardation film may exhibit an inverse dispersion wavelength dependence in which the retardation value increases according to the wavelength of the measurement light. Re(450) / Re(550) of the retardation film is, for example, more than 0.5 and less than 1.0, preferably 0.7 or more and 0.95 or less, more preferably 0.75 or more and 0.92 or less, and still more preferably 0.8 or more and 0.9 or less. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 or more and 1.1 or less.

[0137] Re(450) means the in-plane retardation of the film measured with light of a wavelength of 450 nm at 23°C. Re(550) means the in-plane retardation of the film measured with light of a wavelength of 550 nm at 23°C. Re(λ) is obtained by Re = (nx - ny) × d when the film thickness is d (nm). "nx" means the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction). "ny" means the refractive index in the direction orthogonal to the slow axis in the plane (i.e., the fast axis direction).

[0138] The in-plane retardation Re(550) of the retardation film may be 100 nm or more and 200 nm or less, may be 110 nm or more and 180 nm or less, may be 120 nm or more and 160 nm or less, or may be 130 nm or more and 150 nm or less. The retardation film may function as a so-called λ / 4 plate.

[0139] The retardation film has, for example, in-plane retardation. Therefore, the retardation film may have a relationship of nx > ny. As long as the retardation film has a relationship of nx > ny, it exhibits any appropriate refractive index characteristics. The refractive index characteristics of the retardation film typically show a relationship of nx > ny ≧ nz. "nz" means the refractive index in the thickness direction. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny < nz may occur.

[0140] The Nz coefficient of the retardation film may be 0.9 or more and 2.0 or less, may be 0.9 or more and 1.5 or less, or may be 0.9 or more and 1.2 or less. By satisfying such a relationship, when an optical laminate including the retardation film is used in an image display device, a very excellent reflected hue can be achieved. Here, the "Nz coefficient" is a coefficient obtained by Nz = Rth / Re. "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(450)" is the retardation in the thickness direction of the film measured with light of wavelength 450 nm at 23°C. "Rth(550)" is the retardation in the thickness direction of the film measured with light of wavelength 550 nm at 23°C. Rth(λ) is obtained by Rth = (nx - nz) × d when the thickness of the film is d (nm).

[0141] The thickness of the retardation film can be set so as to function most appropriately as a λ / 4 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. Specifically, the thickness may be 15 μm or more and 80 μm or less, may be 20 μm or more and 70 μm or less, or may be 30 μm or more and 60 μm or less.

[0142] The absolute value of the photoelastic coefficient of the retardation film is 20×10 -12 (m 2 / N) or less, may be 1.0×10 -12 (m 2 / N) to ~15×10 -12 (m 2 / N), and may be 2.0 × 10 -12 (m 2 / N)~12×10 -12 (m 2 When the absolute value of the photoelastic coefficient is within such a range, display unevenness can be suppressed when an optical laminate including the retardation film is applied to an image display device.

[0143] The main surface of the retardation film 2 on which the anchor layer 3 is formed may be subjected to a surface modification treatment. By performing the surface modification treatment, the adhesive strength between the retardation film 2 and the anchor layer 3 can be further improved. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, and flame treatment. The main surface of the retardation film 2 on which the anchor layer 3 is formed may be subjected to corona treatment and / or plasma treatment, or may be subjected to plasma treatment as the surface modification treatment.

[0144] The plasma treatment conditions are expressed in terms of the discharge amount, for example, 0.5 to 100 kJ / m 2 The discharge amount is 1kJ / m 2 More than 2kJ / m 2 or more, and even 5kJ / m 2 The upper limit of the discharge amount is 50 kJ / m 2 , 40kJ / m 2 , 30kJ / m 2 , 20kJ / m 2 , and even 10 kJ / m 2 By appropriately adjusting the amount of discharge in the plasma treatment, the adhesive strength between the retardation film 2 and the anchor layer 3 can be further improved.

[0145] The optical laminate may further include a polarizing film and a surface protective film. An example of such an optical film is shown in Fig. 2. Fig. 2 is a schematic cross-sectional view showing another example of the optical laminate. The optical laminate 1B in Fig. 2 has a laminated structure in which an adhesive sheet 4, an anchor layer 3, a retardation film 2A, an interlayer adhesive sheet 5, a polarizing film 6, and a surface protective film 7 are laminated in this order.

[0146] A known adhesive can be used for the interlayer adhesive sheet 5. The adhesive sheet 4 may be used as the interlayer adhesive sheet 5.

[0147] The polarizing film 6 includes a polarizer. The polarizing film 6 typically includes a polarizer and a protective film (transparent protective film). The protective film is disposed, for example, in contact with the main surface of the polarizer. The polarizer may be disposed between two protective films. The protective film may be disposed on at least one surface of the polarizer.

[0148] The polarizer is not particularly limited, and examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye; and oriented polyene films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Polarizers typically consist of a polyvinyl alcohol film (including partially saponified ethylene-vinyl acetate copolymer films) and a dichroic substance such as iodine.

[0149] The thickness of the polarizer is not particularly limited and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the polarizer thickness is not particularly limited and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, a thickness of 20 μm or less) is suppressed in dimensional change and can contribute to improving the durability of the optical laminate, particularly durability at high temperatures.

[0150] The material for the protective film may be, for example, a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material for the protective film may be a thermosetting resin or an ultraviolet-curable resin such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone-based resin. When the polarizing film has two protective films, the materials of the two protective films may be the same or different. For example, a protective film made of a thermoplastic resin may be bonded to one main surface of a polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curable resin may be bonded to the other main surface of the polarizer. The protective film may contain one or more optional additives, such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

[0151] The thickness of the protective film can be determined as appropriate, but is generally about 10 to 200 μm in terms of strength, workability such as handleability, thinness, and the like.

[0152] The polarizer and the protective film are usually adhered to each other via an aqueous adhesive or the like. Examples of aqueous adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex, aqueous polyurethane, and aqueous polyester. Examples of adhesives other than the above-mentioned adhesives include ultraviolet-curable adhesives and electron beam-curable adhesives. Electron beam-curable polarizing plate adhesives exhibit suitable adhesive properties for various protective films. The adhesive may contain a metal compound filler.

[0153] In the polarizing film 6, a retardation film or the like can be formed on the polarizer instead of a protective film. Another protective film or a retardation film or the like can be further provided on the protective film.

[0154] The protective film may have a hard coat layer on the surface opposite to the surface bonded to the polarizer, and may also be subjected to treatments for the purposes of anti-reflection, anti-sticking, diffusion, anti-glare, etc.

[0155] The polarizing film 6 may be a circular polarizing film.

[0156] The surface protective film 7 functions to protect the polarizing film 6, which is the outermost layer, during distribution and storage of the optical laminate 1B and when the optical laminate 1B is incorporated into an image display device. Furthermore, the surface protective film 7 may also be a protective film that functions as a window to the external space when incorporated into an image display device. The surface protective film 7 is typically a resin film. Examples of resins constituting the surface protective film 7 include polyesters such as PET, polyolefins such as polyethylene and polypropylene, acrylics, cycloolefins, polyimides, and polyamides, with polyesters being preferred. However, the surface protective film 7 is not limited to the above examples. The surface protective film 7 may also be a glass film or a laminate film including a glass film. The surface protective film 7 may be subjected to surface treatments such as anti-glare, anti-reflection, and anti-static.

[0157] The surface protection film 7 may be bonded to the polarizing film 6 with any adhesive. Bonding with an adhesive sheet 4 is also possible.

[0158] The optical laminate of this embodiment is typically used in image display devices, such as liquid crystal displays, organic EL displays, and inorganic EL displays.

[0159] (Method of manufacturing optical laminate) The method for producing an optical laminate according to this embodiment includes applying an anchor layer coating solution containing a solvent S containing an organic solvent and a polymer C to a retardation film to form a coating film having a thickness of T (μm), and drying the coating film. Here, the optical laminate includes a retardation film, an anchor layer, and a pressure-sensitive adhesive sheet. The optical laminate is an optical laminate in which a retardation film, an anchor layer, and a pressure-sensitive adhesive sheet are laminated in this order. The retardation film includes a polycarbonate resin. The anchor layer includes polymer C. In the anchor layer coating solution, the weight ratio Wc of polymer C relative to 100 weight parts of solvent S is 0.01 or more and 0.5 or less. In addition, the equivalent thickness of the coating film calculated by the following formula (1) is 2 μm or more and 10 μm or less. This equivalent thickness is a value converted to the thickness when a coating solution with Wc of 0.1 weight parts is used. Equivalent thickness of coating film = T × Wc / 0.1 (1)

[0160] The method for producing the optical laminate includes forming an anchor layer 3 on a retardation film 2 and forming a pressure-sensitive adhesive sheet 4 on the anchor layer 3.

[0161] Forming the anchor layer 3 on the retardation film 2 includes applying an anchor layer coating liquid to the retardation film 2 to form a coating film with a thickness of T (μm), and drying the obtained coating film.

[0162] Examples of a method for applying the anchor layer coating liquid to the retardation film 2 include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater. The amount of the anchor layer coating liquid to be applied can be appropriately adjusted depending on the desired thickness of the anchor layer 3.

[0163] The thickness of the coating film obtained by applying the anchor layer coating solution to the retardation film 2, i.e., T (μm), may be 1 μm or more and 20 μm or less, 2 μm or more and 10 μm or less, or 2.5 μm or more and 8 μm or less. By appropriately adjusting T (μm), the coating appearance of the resulting anchor layer 3 is improved. The method for measuring T (μm) is described in the Examples section.

[0164] The equivalent thickness of the coating film represented by the above formula (1) is 2 μm or more and 10 μm or less, and may be 4 μm or more and 8 μm or less.

[0165] The coating film is dried to harden the coating film, thereby forming the anchor layer 3. The drying temperature of the coating film is, for example, 100°C or lower, and may be 90°C or lower, 80°C or lower, 70°C or lower, or even 60°C or lower. The drying temperature of the coating film may be room temperature (25°C), 30°C or higher, 40°C or higher, or 45°C or higher.

[0166] The drying time of the coating film can be adjusted appropriately depending on the composition of the anchor layer 3, and may be 5 to 100 seconds, 5 to 70 seconds, or 10 to 35 seconds. By appropriately adjusting the drying time of the coating film, the coating appearance of the anchor layer 3 can be improved.

[0167] After forming the anchor layer 3 on the retardation film 2, the optical laminate 1 can be produced by forming the adhesive sheet 4 on the anchor layer 3. For example, the adhesive sheet 4 can be formed on the anchor layer 3 by transferring the adhesive sheet 4 formed on a release sheet to the anchor layer 3.

[0168] In the method of transferring the adhesive sheet 4 formed on the release sheet to the anchor layer 3, first, the adhesive sheet 4 is formed on the release sheet. The method of forming the adhesive sheet 4 on the release sheet is as explained above in the section [Method of manufacturing adhesive sheet].

[0169] Next, the adhesive sheet 4 is transferred onto the anchor layer 3, whereby the optical laminate 1 can be obtained.

[0170] [Image display device] The image display device includes, for example, an optical laminate and an image forming layer. FIG. 3 is a schematic cross-sectional view showing an example of an image display device according to this embodiment. The image display device 11 in FIG. 3 includes a substrate 9, an image forming layer (e.g., an organic EL layer or a liquid crystal layer) 8, and an optical laminate 1A. In detail, the image display device 11 has a layered structure in which the substrate 9, the image forming layer 8, an adhesive sheet 4, an anchor layer 3, and a retardation film 2 are layered in this order. The image display device 11 may include the optical laminate 1B of FIG. 2 instead of the optical laminate 1A. The substrate 9 and the image forming layer 8 may have the same configurations as the substrate and the image forming layer, respectively, of known image display devices.

[0171] The image display device 11 in Fig. 3 may be an organic EL display or a liquid crystal display. However, the image display device 11 is not limited to this example. The image display device 11 may also be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), or the like. The image display device 11 may be used for home appliances, in-vehicle applications, public information displays (PID), and the like. [Example]

[0172] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the examples shown below.

[0173] [Storage modulus G' (25℃)] The storage modulus G' of the pressure-sensitive adhesive sheet at 25°C was evaluated by the following method. First, a measurement sample was prepared. The measurement sample was a disc-shaped punched out of a laminate in which multiple pressure-sensitive adhesive sheets were laminated. The diameter of the bottom of the measurement sample was 8 mm, and the thickness of the measurement sample was 1 mm. Next, dynamic viscoelasticity measurement was carried out on the measurement sample. ARES-G2 manufactured by TA Instruments was used for the dynamic viscoelasticity measurement. The storage modulus G' of the pressure-sensitive adhesive sheet at 25°C was determined from the results of the dynamic viscoelasticity measurement. The conditions for the dynamic viscoelasticity measurement were as follows: Measurement conditions Frequency: 1Hz Deformation mode: Torsion Measurement temperature: -70℃~150℃ Heating rate: 5°C / min

[0174] [Measurement of coating thickness T (μm)] The thickness T (μm) of the coating film obtained by applying the anchor layer coating solution to the retardation film was measured by the following method. The anchor layer coating solution was applied to the retardation film using a gravure coater under conditions of 23°C and 55% RH, and then the thickness T (μm) of the coating film was immediately measured using a reflection spectroscopic interference film thickness meter (manufactured by Ocean Insight). Additionally, the equivalent thickness of the coating film was calculated using the following formula (1) when the weight parts Wc of polymer C relative to 100 weight parts of solvent S was set to 0.1. Equivalent thickness of coating film = T × Wc / 0.1 (1)

[0175] [Normal adhesion] The substrate-attached optical laminates of each Example and Comparative Example were cut to a size of 25 cm x 25 cm. Next, the substrate was peeled from the substrate-attached optical laminate to expose the adhesive sheet, thereby producing an optical laminate. The optical laminate was then bonded to an ITO film via the adhesive sheet of the optical laminate, using a 2 kg roller to roll it back and forth once. Within one minute, the optical laminate was peeled from the ITO film using a tensile tester (manufactured by Minebea Co., Ltd., product name: TG-1KN) at a peel angle of 180° and a peel speed of 300 mm / min, and the peel force was measured. Normal adhesion was evaluated according to the following criteria. The ITO film used was a polyethylene terephthalate film "125 Tetolite OES" (manufactured by Oike Kogyo Co., Ltd.) that had been vapor-deposited with SiO2. The adhesive sheet was attached to the surface on which SiO2 had been vapor-deposited. A: Peeling force is 20N or more B: Peeling force is 15N or more and less than 20N C: Peeling force is greater than 10N and less than 15N D: Peeling force is 10N or less

[0176] [Promotes adhesion] The optical laminates with a substrate according to each example and comparative example were stored for at least three days under an environment of 40°C and 92% RH. After storage, the optical laminates with a substrate were removed and allowed to stand at room temperature for one hour. The optical laminates with a substrate were then cut into pieces measuring 25 cm x 25 cm. Next, the substrate was peeled from the optical laminate with a substrate to expose the adhesive sheet, thereby producing an optical laminate. The optical laminate was then bonded to an ITO film via the adhesive sheet of the optical laminate, using a 2 kg roller and rolling it back and forth once. Within one minute, the optical laminate was peeled from the ITO film using the tensile tester at a peel angle of 180° and a peel speed of 300 mm / min, and the peel force was measured. Accelerated adhesion was evaluated according to the following criteria. The ITO film used was the polyethylene terephthalate film "125 Tetolite OES" vapor-deposited with SiO2. The adhesive sheet was attached to the SiO2-deposited surface. A: Peeling force is 20N or more B: Peeling force is 15N or more and less than 20N C: Peeling force is greater than 10N and less than 15N D: Peeling force is 10N or less

[0177] [Impact resistance] An optical laminate with a substrate for impact resistance evaluation was produced by laminating an interlayer adhesive sheet, a polarizing plate, and a surface protective film in that order to the retardation film of the optical laminate with a substrate according to each example and comparative example.

[0178] (Preparation of interlayer adhesive sheet) <Preparation of Acrylic Polymer A1> A four-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser was charged with a monomer mixture containing 82.1 parts butyl acrylate, 13 parts benzyl acrylate, 0.1 parts 4-hydroxybutyl acrylate, and 4.8 parts acrylic acid. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts ethyl acetate were charged to 100 parts of this monomer mixture, and nitrogen gas was introduced to replace the atmosphere with nitrogen while gently stirring. The temperature in the flask was then maintained at around 55°C for 8 hours to produce a solution of acrylic polymer A1 with a weight average molecular weight (Mw) of 2.2 million and Mw / Mn = 3.0.

[0179] An interlayer adhesive composition was obtained by blending 100 parts of the solid content of the acrylic polymer A1 solution with 0.45 parts of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L"), 0.1 parts of a peroxide crosslinking agent (benzoyl peroxide), 0.2 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403"), and 0.25 parts of a polyether compound having a reactive silyl group (manufactured by Kaneka Corporation, product name "Silyl SAT10").

[0180] The interlayer adhesive composition was uniformly applied to the surface of a polyethylene terephthalate film (release film) treated with a silicone-based release agent using a fountain coater to obtain a coating film, which was then dried for 2 minutes in an air-circulating thermostatic oven at 155°C to form an interlayer adhesive sheet with a thickness of 20 μm on the surface of the release film.

[0181] (Preparation of polarizing plate P1) To prepare a polarizing plate, a polarizer was first prepared as follows. A long polyvinyl alcohol (PVA) resin film (manufactured by Kuraray Co., Ltd., product name "PE3000," thickness 30 μm) was uniaxially stretched in the longitudinal direction (total stretching ratio 5.9 times) using a roll stretching machine. At the same time, the resin film was subjected to the following treatments in order: swelling, dyeing, crosslinking, washing, and drying, to prepare a 12 μm-thick polarizer. In the swelling treatment, the resin film was stretched 2.2 times while being treated with pure water at 20°C. In the dyeing treatment, the resin film was stretched 1.4 times while being treated with an aqueous solution at 30°C containing iodine and potassium iodide in a weight ratio of 1:7. The iodine concentration in the aqueous solution was adjusted so that the single transmittance of the prepared polarizer would be 45.0%. A two-stage crosslinking treatment was used. In the first crosslinking step, the resin film was stretched 1.2 times while being treated with a 40°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the first crosslinking step was 5.0 wt %, and the potassium iodide content was 3.0 wt %. In the second crosslinking step, the resin film was stretched 1.6 times while being treated with a 65°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the second crosslinking step was 4.3 wt %, and the potassium iodide content was 5.0 wt %. A 20°C aqueous potassium iodide solution was used for the washing step. The potassium iodide content of the aqueous solution used for the washing step was 2.6 wt %. The drying step was carried out at 70°C for 5 minutes.

[0182] A triacetyl cellulose (TAC) film (Konica Minolta, product name "KC2UA", thickness 25 μm) was attached to each main surface of the prepared polarizer using a polyvinyl alcohol adhesive. However, the TAC film attached to one main surface had a hard coat (thickness 7 μm) formed on the main surface opposite the polarizer side. In this way, a polarizing plate P1 having a configuration of protective layer with hard coat / polarizer / protective layer (without hard coat) was obtained.

[0183] (Preparation of an optical laminate with a substrate for impact resistance evaluation) An interlayer adhesive sheet formed on the surface of a release film was transferred to the surface on which the retardation film was formed of the substrate-attached optical laminate of each Example and Comparative Example, to produce an optical laminate with an interlayer adhesive sheet. The release film of the optical laminate with the interlayer adhesive sheet was peeled off, and a polarizing plate P1 and a surface protective film were laminated in this order. In this way, an optical laminate with a substrate for impact resistance evaluation was produced. The optical laminate with a substrate for impact resistance evaluation had a structure in which the substrate, adhesive sheet, anchor layer, retardation film, interlayer adhesive sheet, polarizing plate P1, and surface protective film were laminated in this order. For the surface protective film, a surface protective film for electronic and engineering components (PET material, product name: E-MASK RP109F) manufactured by Nitto Denko Corporation was used.

[0184] (End processing) Edge treatment was performed on an optical laminate with a substrate for impact resistance evaluation. First, a laminate was produced by stacking 100 optical laminates with a substrate for impact resistance evaluation. The laminate was held in a pressurized state from above and below with a vise-like jig in the stacking direction of the laminate. Next, edge treatment was performed by cutting 1.0 mm inward from the edge of the laminate in a direction perpendicular to the stacking direction of the laminate using a rotary blade. This produced a sample for impact resistance evaluation.

[0185] [Impact resistance evaluation method] Adhesive tape (Sekisui Cellotape, No. 252) was wrapped around a metal rod with a diameter of approximately 4 mm via double-sided tape. This metal rod was then pushed into the edge of the impact resistance evaluation sample. Specifically, the metal rod was first positioned so that its longitudinal axis was aligned with the lamination direction of the impact resistance evaluation sample and in contact with the edge of the impact resistance evaluation sample. Next, the metal rod was pushed approximately 5 mm inward from the edge of the impact resistance evaluation sample in a direction perpendicular to the lamination direction of the impact resistance evaluation sample. While maintaining contact between the metal rod and the edge of the impact resistance evaluation sample, the metal rod was pulled from the surface protective film of the impact resistance evaluation sample toward the substrate. In this way, the edge of the impact resistance evaluation sample was rubbed with the metal rod. Thereafter, the rubbed portion was observed using an optical microscope (differential interference microscope; manufactured by Nikon Corporation) for chipping of the adhesive from the edge of the impact resistance evaluation sample, and the impact resistance was evaluated according to the following criteria. Here, "depth from the edge of the adhesive chip" means the maximum distance in the direction of the adhesive sheet that is missing from the edge of the sample for impact resistance evaluation to the inside of the surface direction in the missing part of the adhesive sheet. A: The depth from the edge of the adhesive chip is less than 100 μm B: The depth from the edge of the adhesive chip is 100 μm or more

[0186] [Anchor layer thickness measurement] In each example and comparative example, a retardation film with an anchor layer was dyed with a 2% ruthenic acid aqueous solution for 2 minutes to prepare a sample. The sample was then embedded in epoxy resin and cut to a thickness of approximately 80 nm using an ultramicrotome (Ultracut S, manufactured by Leica) to prepare a film slice for measurement. The cross section of the film slice for measurement was then observed using a TEM (Hitachi H-7650, accelerating voltage 100 kV). The "thickness of the anchor layer" was defined as the average value of the minimum thickness of the anchor layer obtained by measurement and the maximum thickness of the anchor layer obtained by measurement.

[0187] [Preparation of optical laminate with substrate] Example 1 <Preparation of Pressure-Sensitive Adhesive Composition> A reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer was charged with 76.1 parts by weight of butyl acrylate, 0.1 parts by weight of 4-hydroxybutyl acrylate, and 2,2-azobisisobutyronitrile (0.3 parts by weight per 100 parts by weight of monomer (solid content)) together with ethyl acetate, and the mixture was reacted under a nitrogen gas stream at 60°C for 4 hours to prepare a reaction solution. Ethyl acetate was then added to this reaction solution to obtain polymer solution A containing an acrylic polymer with a weight-average molecular weight of 2.2 million. 2.5 parts by weight of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D101E"), 0.04 parts by weight of epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"), and 1 part by weight of polyether compound having a reactive silyl group (manufactured by Kaneka Corporation, trade name "Silyl SAT10") were blended with 100 parts by weight of the solid content of acrylic polymer solution A to obtain pressure-sensitive adhesive composition PSA1.

[0188] <Preparation of anchor layer coating solution> An anchor layer coating solution was prepared by adding a solution containing 50% or more by weight of a polyurethane polymer (manufactured by Nagase ChemteX Corporation, product name "Denatron B-510C") and a solution containing 10 to 70% by weight of an oxazoline group-containing acrylic polymer and 10 to 70% by weight of a polyoxyethylene group-containing methacrylate (manufactured by Nippon Shokubai Co., Ltd., product name "Epocross WS-700") to a mixed solvent containing 35% by weight of water and 65% by weight of isopropyl alcohol (IPA). The anchor layer coating solution contained a polyurethane polymer, an oxazoline group-containing acrylic polymer, and a polyoxyethylene group-containing methacrylate as polymer C. In the anchor layer coating solution, the weight ratio of the polyurethane polymer to 100 parts by weight of the mixed solvent was 0.017. The total weight ratio of the oxazoline group-containing acrylic polymer and the polyoxyethylene group-containing methacrylate to 100 parts by weight of the mixed solvent was 0.033. In the anchor layer coating solution, the weight ratio Wc of polymer C relative to 100 weight parts of the mixed solvent was 0.05.

[0189] <Preparation of retardation film with anchor layer> The retardation film with an anchor layer was produced by the roll-to-roll method. One side of a retardation film (polycarbonate resin film, product name: Pure Ace RM-147) manufactured by Teijin Ltd. was plasma-treated on the production line (discharge amount: 5.83 kJ / m). 2 ) was carried out. Then, using a gravure coater, the anchor layer coating liquid was applied to the plasma-treated surface of the retardation film to form a coating film with a thickness of 5 μm. The coating film was then dried at 50°C to produce a retardation film with an anchor layer. This film was wound up in a long length.

[0190] <Preparation of optical laminate with substrate> The pressure-sensitive adhesive composition PSA1 was uniformly applied to the surface of a polyethylene terephthalate film (substrate) treated with a silicone-based release agent using a fountain coater to obtain a coating film. The coating film was then dried for 2 minutes in an air-circulating thermostatic oven at 155°C to form a pressure-sensitive adhesive sheet on the surface of the substrate. The thickness of the pressure-sensitive adhesive sheet was 15 μm. The storage modulus G' of the pressure-sensitive adhesive sheet at 25°C was 0.180 MPa.

[0191] Next, the pressure-sensitive adhesive sheet formed on the surface of the substrate was transferred to the surface of the anchor layer of the anchor layer-attached retardation film to produce an optical laminate with a substrate according to Example 1. The optical laminate with a substrate had the substrate, pressure-sensitive adhesive sheet, anchor layer, and retardation film laminated in this order.

[0192] (Example 2 7. Reference Examples 1-2 and Comparative Examples 1 to 5) table 1 The same method as in Example 1 was used except that the conditions were changed as described in Example 2 to Example 3. 7. Reference Examples 1-2 Optical laminates with a substrate according to Comparative Examples 1 to 5 were produced.

[0193] [Table 1]

[0194] As shown in Table 1, the optical laminates according to the examples were superior in impact resistance and adhesion to the optical laminates according to the comparative examples. [Industrial Applicability]

[0195] The optical layered body of the present invention can be used, for example, in an image display device. [Explanation of symbols]

[0196] 1A, 1B Optical laminate 2 Phase difference film 2A Retardation Film 3 Anchor layer 4 adhesive sheets 5 Interlayer adhesive sheet 6. Polarizing film 7 Surface protection film 8. Image forming layer 9 Substrate 11 Image display devices

Claims

1. An optical laminate comprising a retardation film containing a polycarbonate-based resin, an anchor layer containing polymer C, and a pressure-sensitive adhesive sheet, wherein the retardation film, the anchor layer, and the pressure-sensitive adhesive sheet are laminated in this order, the polymer C contains a polyoxyalkylene group-containing polymer and a polyurethane-based polymer, the anchor layer has a thickness of 15 nm or more and 23 nm or less; the pressure-sensitive adhesive sheet is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, The pressure-sensitive adhesive sheet has a storage modulus of 0.15 MPa or more at 25°C.

2. An image display device comprising the optical laminate according to claim 1 and an image forming layer.

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