Optical laminate and image display device using the optical laminate

Abstract

To provide an optical laminate in which frame-shaped display defects are suppressed. [Solution] An optical laminate according to an embodiment of the present invention comprises, in this order, a front plate, an adhesive layer, a polarizing plate, and a phase difference layer. The polarizing plate includes a polarizer and a protective layer disposed on the adhesive layer side of the polarizer. The adhesive layer is composed of a photocurable adhesive containing a compound whose absorption maximum wavelength is 200 nm to 300 nm. The transmittance of the polarizer alone is 43.3% or higher. Alternatively, the moisture permeability of the protective layer is 100 g / cm³. 2 • Less than 24 hours

Description

[Technical Field]

[0001] The present invention relates to an optical laminate and an image display device using the optical laminate. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), have become widespread. Typically, polarizing plates and phase difference plates are used in these image display devices. These polarizing plates and phase difference plates are sometimes integrated with a front plate via an adhesive layer to form an optical laminate. However, when such optical laminates are exposed to sunlight after being placed in a high-temperature, high-humidity environment, a red, frame-shaped display defect (hereinafter simply referred to as a frame-shaped display defect) visible due to reflection may occur. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-64290 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide an optical laminate in which frame-shaped display defects are suppressed. [Means for solving the problem]

[0005] An optical laminate according to an embodiment of the present invention comprises, in this order, a front plate, an adhesive layer, a polarizing plate, and a phase difference layer. The polarizing plate includes a polarizer and a protective layer disposed on the adhesive layer side of the polarizer. The adhesive layer is composed of a photocurable adhesive containing a compound whose absorption maximum wavelength is 200 nm to 300 nm. The transmittance of the polarizer alone is 43.3% or higher. Alternatively, the moisture permeability of the protective layer is 100 g / cm³.2 ·It is less than 24 hours. In one embodiment, the compound having an absorption maximum wavelength of 200 nm to 300 nm is a benzophenone compound. In one embodiment, the thickness of the polarizer is 10 μm or less, and the iodine concentration is 10 wt% or less. In one embodiment, the retardation layer has a circular polarization function or an elliptical polarization function. In one embodiment, the retardation layer is composed of a stretched film of a resin film, Re(550) thereof is 100 nm to 200 nm, it satisfies the relationship of Re(450) < Re(550), and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°. In one embodiment, the optical laminate further has another retardation layer on the side opposite to the polarizer of the retardation layer, and the refractive index characteristics thereof show the relationship of nz > nx = ny. In one embodiment, a hard coat layer is formed on the adhesive layer side of the protective layer. In one embodiment, the thickness of the adhesive layer is 50 μm to 500 μm. According to another aspect of the present invention, an image display device is provided. This image display device includes the above optical laminate.

Advantages of the Invention

[0006] According to the embodiment of the present invention, an optical laminate with suppressed frame-shaped display defects can be realized.

Brief Description of the Drawings

[0007] [Figure 1] It is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

Modes for Carrying Out the Invention

[0008] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] (Definitions of terms and symbols) The definitions of terms and symbols used in this specification are as follows: (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction where the refractive index is maximum in the plane (i.e., the slow phase axis direction), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., the fast phase axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane phase difference of a film measured with light of wavelength λnm at 23°C. For example, "Re(550)" is the in-plane phase difference of a film measured with light of wavelength 550nm at 23°C. Re(λ) can be calculated using the formula: Re=(nx-ny)×d, where d(nm) is the thickness of the film. (3) Phase difference in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction of the film measured with light of wavelength λnm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction of the film measured with light of wavelength 550nm at 23°C. Rth(λ) can be calculated using the formula: Rth = (nx - nz) × d, where d (nm) is the thickness of the film. (4) Nz coefficient The Nz coefficient is calculated using the formula Nz = Rth / Re. (5)Angle In this specification, when an angle is mentioned, unless otherwise specified, it includes angles in both clockwise and counterclockwise directions.

[0010] A. Overall configuration of the optical laminate Figure 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The illustrated optical laminate 100 has, in this order, a front plate 10, an adhesive layer 20, a polarizing plate 30, and a phase difference layer 40. That is, in the optical laminate 100, the front plate 10 and the polarizing plate 30 are laminated with the adhesive layer 20 in between. The polarizing plate 30 includes a polarizer 31 and a protective layer 32 disposed on the adhesive layer 20 side of the polarizer 31. Depending on the purpose, the polarizing plate 30 may further include another protective layer (not shown) disposed on the opposite side of the polarizer from the adhesive layer 20.

[0011] In embodiments of the present invention, the adhesive layer 20 is composed of a photocurable adhesive containing a compound whose absorption maximum wavelength is 200 nm to 300 nm. Furthermore, the transmittance of the polarizer 31 is 43.3% or higher, or the moisture permeability of the protective layer 32 is 100 g / cm³. 2 · The exposure time is 24 hours or less. If the transmittance of the polarizer alone or the moisture permeability of the protective layer is within this range, frame-shaped display defects can be suppressed in optical laminates. More specifically, the following applies. A new problem has been recognized in which frame-shaped display defects occur when an optical laminate in which the front plate is integrated with a polarizer, etc., via an adhesive layer is exposed to sunlight after being placed in a high-temperature, high-humidity environment. The inventors diligently investigated frame-shaped display defects and estimated that they are due to local anisotropic reflection of the polarizer. Based on this estimation, the inventors further investigated frame-shaped display defects and found that the cause lies in the adhesive layer, and that frame-shaped display defects occur when the adhesive layer contains a compound with an absorption maximum wavelength of 200 nm to 300 nm. Based on this finding, the inventors further investigated and found that by controlling the transmittance of the polarizer alone or the moisture permeability of the protective layer to a predetermined range, the migration and / or non-uniform distribution of the compound is suppressed, and as a result, frame-shaped display defects are suppressed, thus completing the present invention. In other words, the embodiments of the present invention solve newly discovered problems in optical laminates of a specific configuration, and the effect is an unexpectedly excellent effect. Hereinafter, "compounds with an absorption maximum wavelength of 200 nm to 300 nm" may be referred to as "absorbent compounds" for convenience.

[0012] The phase difference layer 40 typically has a circular polarization function or an elliptical polarization function. With such a configuration, an optical laminate with excellent anti-reflective properties can be obtained. In one embodiment, the phase difference layer 40 is composed of a stretched resin film. In this case, the phase difference layer 40 is typically a single layer. In another embodiment, the phase difference layer 40 is an orientation solidified layer of a liquid crystal compound (hereinafter sometimes referred to as the liquid crystal orientation solidified layer). In this case, the phase difference layer 40 may be a single layer or may have a two-layer structure consisting of a first liquid crystal orientation solidified layer and a second liquid crystal orientation solidified layer. Details of the phase difference layer 40 will be described later in section E.

[0013] In one embodiment, the optical laminate may further have another phase difference layer 50 on the opposite side of the phase difference layer 40 from the polarizer plate 30. Typically, the other phase difference layer 50 exhibits a refractive index characteristic such as nz > nx = ny. By providing such an additional phase difference layer, oblique reflections can be effectively prevented, enabling a wider viewing angle for the anti-reflective function.

[0014] In one embodiment, a hard coat layer 33 may be formed on the adhesive layer 20 side of the protective layer 32 of the polarizing plate 30. With such a configuration, the transfer of the light-absorbing compound from the adhesive layer to the polarizing plate (substantially, the polarizer) can be suppressed even more effectively. As a result, frame-shaped display defects can be suppressed even more effectively.

[0015] In practical terms, the optical laminate has another adhesive layer (not shown) as the outermost layer opposite the front plate 10, and is designed to be attachable to an image display cell. In this case, it is preferable that a release liner is temporarily attached to the surface of the other adhesive layer until the optical laminate is put into use. By temporarily attaching the release liner, the other adhesive layer is protected, and the roll formation of the optical laminate becomes possible.

[0016] The following describes the components of the optical laminate.

[0017] B. Front plate As the front panel 10, any suitable film or plate can be used depending on the purpose. For example, the front panel may be made of glass or resin. The light transmittance of the front panel at a wavelength of 550 nm is preferably 85% or more. The refractive index of the front panel at a wavelength of 550 nm is preferably 1.4 to 1.65.

[0018] Any suitable configuration can be used as the glass plate for use as the front panel of an image display device. The thickness of the glass plate is, for example, 1 mm to 10 mm. By using a glass plate as the front panel, an optical laminate with extremely excellent mechanical strength and surface hardness can be obtained. Examples of glass, according to its composition, include soda-lime glass, boric acid glass, aluminosilicate glass, and quartz glass. According to its alkali content, examples include alkali-free glass and low-alkali glass. The alkali metal content of the glass (e.g., Na2O, K2O, Li2O) is preferably 15% by weight or less, and more preferably 10% by weight or less. The density of the glass is preferably 2.3 g / cm³. 3 ~3.0g / cm 3 More preferably 2.3 g / cm³ 3 ~2.7g / cm 3 Therefore, if the density of the glass is within this range, it is possible to reduce the weight of the optical laminate.

[0019] Any suitable configuration can be used as the resin plate for use as the front panel of an image display device. Examples of materials that make up the resin plate include acrylic resin, styrene resin, acrylonitrile-styrene resin (AS resin), polycarbonate resin, polyester resin, and polyolefin resin. The thickness of the resin plate is, for example, 1 mm to 10 mm. By using a predetermined resin plate as the front panel, it is possible to achieve a surface hardness that is not problematic in practical use, and to reduce the weight compared to a glass plate. Furthermore, by using a resin with higher transparency than glass, low power consumption can be achieved.

[0020] C. Adhesive layer As described above, the adhesive layer is composed of a photocurable adhesive containing a compound (absorbent compound) whose absorption maximum wavelength is 200 nm to 300 nm. A detailed explanation follows.

[0021] C-1. Characteristics of the adhesive layer The glass transition temperature of the adhesive layer is preferably -3°C or lower, more preferably -5°C or lower, and even more preferably -6°C or lower. On the other hand, the glass transition temperature is preferably -20°C or higher, more preferably -15°C or higher, and even more preferably -13°C or higher. If the glass transition temperature is within this range, an adhesive layer with excellent impact resistance can be realized.

[0022] The peak-top value of the loss tangent tanδ of the adhesive layer (i.e., tanδ at the glass transition temperature) is preferably 1.5 or higher, more preferably 1.6 or higher, even more preferably 1.7 or higher, and particularly preferably 1.75 or higher. On the other hand, the upper limit of the peak-top value of tanδ is preferably 3.0 or lower, more preferably 2.5 or lower, and even more preferably 2.3 or lower. If the peak-top value of tanδ is within this range, the adhesive layer exhibits appropriate deformation behavior (viscoelastic behavior), so that, for example, when a deformed part such as a through hole is formed in the polarizing plate, gaps are less likely to form when filling the deformed part.

[0023] The total light transmittance of the adhesive layer is preferably 85% or more, and more preferably 90% or more. The haze value of the adhesive layer is preferably 1.5% or less, and more preferably 1.0% or less.

[0024] The thickness of the adhesive layer is preferably 50 μm to 500 μm, more preferably 70 μm to 350 μm, even more preferably 80 μm to 250 μm, and particularly preferably 100 μm to 200 μm.

[0025] C-2. Photocurable adhesive C-2-1. Characteristics of photocurable adhesives The storage elastic modulus of the photocurable adhesive at 60°C after curing is preferably 5.0×10 3 Pa to 5.0×10 5 Pa, more preferably 7.5×10 3 Pa to 4.0×10 5 Pa, and even more preferably 8.0×10 3 Pa to 3.0×10 5 Pa. If the storage elastic modulus of the photocurable adhesive after curing is within such a range, the gel elasticity of the adhesive layer becomes low and the residual stress becomes small.

[0026] The gel fraction of the photocurable adhesive after curing is preferably 50% to 95%, more preferably 55% to 93%, and even more preferably 60% to 90%. If the gel fraction of the photocurable adhesive after curing is within such a range, the front panel and the polarizing plate can be firmly fixed. The gel fraction can be determined as the insoluble content in a solvent such as ethyl acetate. Specifically, the gel fraction is determined as the weight fraction (unit: wt%) of the insoluble component after immersing the adhesive constituting the adhesive layer in ethyl acetate at 23°C for 7 days with respect to the sample before immersion. The gel fraction can be adjusted by appropriately setting the types, combinations, and blending amounts of the monomer components constituting the base polymer of the adhesive, as well as the types and blending amounts of the crosslinking agent, etc.

[0027] C-2-2. Constituent Materials of the Photocurable Adhesive As a photocurable adhesive, any suitable photocurable adhesive (which may be simply referred to as an adhesive composition in this section) can be used, as long as it has the characteristics described above. Examples of base polymers for the adhesive composition include (meth)acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy polymers, fluorine polymers, natural rubber, synthetic rubber, and other rubber polymers. Preferably, the adhesive composition contains a (meth)acrylic polymer as the base polymer. This is because it has excellent optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive properties, and also has excellent weather resistance and heat resistance. In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0028] C-2-2-1. (Meth)acrylic-based polymer (Meth)acrylic-based polymers contain alkyl (meth)acrylate as the main monomer component. Alkyl (meth)acrylates with 1 to 20 carbon atoms in the alkyl group are preferably used. The alkyl (meth)acrylate may have branched alkyl groups or cyclic alkyl groups. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isobornyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and stearyl groups. Alkyl (meth)acrylates can be used alone or in combination. Preferred alkyl groups are methyl, butyl, 2-ethylhexyl, isobornyl, and stearyl groups; more preferred alkyl groups are methyl, 2-ethylhexyl, and isobornyl groups.

[0029] Alkyl (meth)acrylate can be used in a proportion of preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and even more preferably 60 parts by weight or more, when the total amount of monomer components constituting the (meth)acrylic base polymer is 100 parts by weight.

[0030] (Meth)acrylic-based polymers may contain monomer components copolymerizable with alkyl (meth)acrylates (hereinafter referred to as copolymer monomers). Examples of copolymer monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, nitrogen atom-containing monomers, cyclopolymerizable monomers, and epoxy group-containing monomers. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. Examples of carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of nitrogen atom-containing monomers include N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and N-vinylpyrrolidone. Examples of cyclopolymerizable monomers include alkoxyalkyl acrylates. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. The type, number, combination, and amount of copolymerized monomers can be appropriately set according to the purpose.

[0031] Preferred monomer component combinations may include, for example, 2-ethylhexyl(meth)acrylate / methyl(meth)acrylate / 2-hydroxyethyl(meth)acrylate, 2-ethylhexyl(meth)acrylate / isobornyl(meth)acrylate / methyl(meth)acrylate / 2-hydroxyethyl(meth)acrylate, or butyl(meth)acrylate / cyclohexyl(meth)acrylate / stearyl(meth)acrylate / 4-hydroxybutyl(meth)acrylate / N-vinylpyrrolidone.

[0032] C-2-2-2.Light absorbing compound Absorbing compounds can typically function as photopolymerization initiators. The effects of the embodiments of the present invention are particularly pronounced in optical laminates having an adhesive layer containing such compounds. Specifically, even when the adhesive layer contains such compounds, optical laminates with suppressed frame-like display defects can be realized. Examples of such compounds include benzophenone compounds, anthraquinone compounds, and phenanthrenequinone compounds. Benzophenone compounds are preferred. The effects of the embodiments of the present invention become even more pronounced when the adhesive layer contains a benzophenone compound. Examples of benzophenone compounds include benzophenone, methylbenzophenone, trimethylbenzophenone, methyl benzoylbenzoate, 4,4'-bis(diethylamino)benzophenone, methyl-o-benzoylbenzoate, [4-(methylphenylthio)phenyl]phenylmethane, and 2,2-dimethoxy-2-phenylacetophenone. Benzophenone compounds may be used alone or in combination.

[0033] The light-absorbing compound may be included in the adhesive composition in a ratio of preferably 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.1 parts by weight, per 100 parts by weight of the base polymer.

[0034] C-2-2-3. Other components of adhesive compositions The adhesive composition (photocurable adhesive) may include, in addition to the above-mentioned base polymer and light-absorbing compound, a thermal polymerization initiator and a silane coupling agent.

[0035] Any suitable radical-type thermal polymerization initiator can be used as the thermal polymerization initiator. Specific examples include azobisisobutyronitrile and 2,2'-azobis(2,4-dimethylvaleronitrile). The thermal polymerization initiator may be included in the adhesive composition in a ratio of preferably 0.01 to 0.5 parts by weight, more preferably 0.01 to 0.1 parts by weight, per 100 parts by weight of the base polymer.

[0036] Any suitable silane coupling agent can be used. The adhesive strength of the photocurable adhesive can be adjusted by using a silane coupling agent. The content of the silane coupling agent in the adhesive composition is preferably 0.01 to 5 parts by weight, and more preferably 0.03 to 2 parts by weight, per 100 parts by weight of the base polymer.

[0037] The adhesive composition (photocurable adhesive) may further contain oligomers and / or polyfunctional compounds. Any suitable oligomer can be used as the oligomer. By using oligomers, the viscoelasticity (and therefore, fluidity, workability) and adhesive strength of the photocurable adhesive can be adjusted. The oligomer is preferably a (meth)acrylic oligomer. (Meth)acrylic oligomers can have excellent compatibility with the base polymer. The weight-average molecular weight of the oligomer is preferably about 1000 to 30000, more preferably 1500 to 10000, and even more preferably 2000 to 8000. If the weight-average molecular weight of the oligomer is within this range, excellent adhesive strength and adhesion retention can be achieved. Examples of polyfunctional compounds include compounds containing two or more polymerizable functional groups (ethylenically unsaturated groups) having unsaturated double bonds in one molecule. Polyfunctional compounds are typically photopolymerizable polyfunctional compounds. As the polyfunctional compound, polyfunctional (meth)acrylates are preferred because they readily copolymerize with monomer components of (meth)acrylic polymers. By using a polyfunctional compound, an appropriate cross-linking structure can be introduced into the resulting adhesive layer. As a result, the front plate and the polarizing plate can be firmly bonded together, and an adhesive layer with excellent impact resistance and deformability can be realized. The type, number, combination, and amount of oligomers and polyfunctional compounds can be appropriately set according to the purpose.

[0038] The adhesive composition (photocurable adhesive) may further contain any suitable additives depending on the purpose. Specific examples of additives include antioxidants, antistatic agents, rework improvers, colorants, pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, conductive agents, inorganic or organic fillers, metal powders, particulate matter, and foil-like materials. Furthermore, a redox system with a reducing agent may be adopted within a controllable range. The type, number, combination, and amount of additives can be appropriately determined depending on the purpose.

[0039] C-3. Method for forming the adhesive layer The adhesive layer can be partially cured by thermal polymerization and then fully cured by photopolymerization. Therefore, the above-mentioned light-absorbing compound can function not only as a photopolymerization initiator but also as a photocrosslinking agent. In one embodiment, the front plate and the polarizing plate can be laminated via a partially cured adhesive layer. With such a configuration, if a shape-reduced portion, such as a through-hole, is formed on the polarizing plate, the shape-reduced portion can be filled without gaps.

[0040] D. Polarizing plate D-1.Polarizer Any suitable polarizer can be used as the polarizer 31. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0041] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to dyeing and stretching treatments with dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA film with iodine and uniaxially stretching are used because they have excellent optical properties.

[0042] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA film in water and washing it before dyeing can not only clean dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film to prevent uneven dyeing.

[0043] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps in which the laminate is immersed in liquid, such as dyeing and water-based stretching, can be improved. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0044] The thickness of the polarizer is preferably 10 μm or less, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. The effects of the embodiments of the present invention are particularly noticeable in optical laminates having such very thin polarizers. More specifically, the effects are as follows: Such very thin polarizers generally have a high iodine concentration, and it is presumed that frame-shaped display defects may occur due to anisotropic reflection caused by the interaction between iodine and the above-mentioned light-absorbing compound. According to the embodiments of the present invention, by controlling the transmittance of the polarizer alone or the moisture permeability of the protective layer on the adhesive layer side, such interactions can be reduced and frame-shaped display defects can be suppressed. It should be noted that this mechanism is merely a presumption, and this presumption does not restrict the present invention or its mechanism. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0045] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer alone is 43.3% or higher, preferably 43.3% to 46.0%, and more preferably 43.3% to 45.0%, as described above. If the transmittance of the polarizer alone is within this range, the iodine concentration can be controlled to a desired range, and as a result, frame-shaped display defects can be suppressed. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher. According to embodiments of the present invention, even if the transmittance of the polarizer alone is within the above range, the degree of polarization can be maintained within this range.

[0046] The iodine concentration of the polarizer is preferably 10% by weight or less, more preferably 3% to 8% by weight, and even more preferably 5% to 7% by weight. When the iodine concentration is within this range, the interaction between iodine and the above-mentioned light-absorbing compound can be reduced, and therefore, anisotropic reflection caused by this interaction can be reduced. As a result, frame-shaped display defects can be suppressed in optical laminates having very thin polarizers. In this specification, "iodine concentration" means the total amount of iodine contained in the polarizer. More specifically, in the polarizer, iodine is I - , I2, I3 - Iodine exists in various forms, and in this specification, iodine concentration refers to the concentration of iodine encompassing all of these forms. Iodine concentration can be calculated, for example, from the fluorescence X-ray intensity obtained by fluorescence X-ray analysis and the film (polarizer) thickness.

[0047] D-2.Protective layer The protective layer 32 has a moisture permeability of 100 g / cm² as described above. 2 • Less than 24 hours, preferably 70 g / cm³ 2 • Less than 24 hours, and more preferably 50 g / cm³ 2 • Less than 24 hours, and particularly preferably 40 g / cm³ 2 • Less than 24 hours, and particularly preferably 30 g / cm³ 2 • Less than 24 hours, most preferably 25 g / cm³ 2 • Less than 24 hours. The lower limit of moisture permeability is, for example, 5 g / cm². 2 It can be 24 hours. If the moisture permeability of the protective layer is within this range, the transfer of the light-absorbing compound from the adhesive layer to the polarizing plate (essentially, the polarizer) can be effectively suppressed. As a result, frame-shaped display defects can be effectively suppressed.

[0048] The protective layer 32 is composed of any suitable resin film, provided that it can achieve the above-mentioned range of moisture permeability. Typical materials for the resin film include cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. Typical examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. The protective layer 32 is preferably composed of a cycloolefin resin or a (meth)acrylic resin.

[0049] The optical laminate is typically positioned on the viewing side of the image display device, and the protective layer 32 is typically positioned on the viewing side. Therefore, the protective layer 32 may be surface-treated as needed. Examples of surface treatments include hard coating, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment. In embodiments of the present invention, hard coating (formation of a hard coating layer) is preferred. The hard coating layer will be described later. Hard coating and other surface treatments may be applied in combination. Furthermore / or, the protective layer 32 may be treated as needed to improve visibility when viewed through polarized sunglasses (typically, by providing (elliptic) circular polarization function or providing ultra-high phase difference). By applying such treatment, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the optical laminate can be suitably applied to image display devices that can be used outdoors.

[0050] The thickness of the protective layer 32 is preferably 15 μm to 80 μm, more preferably 20 μm to 60 μm, and even more preferably 25 μm to 45 μm. If a surface treatment is applied, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0051] The additional protective layer (if any) is formed from any suitable film that can be used as a protective layer for the polarizer. Typical materials for the additional protective layer include cellulosic resins such as triacetylcellulose (TAC), cycloolefin resins, (meth)acrylic resins, polyester resins, polyolefin resins, and polycarbonate resins. The thickness of the additional protective layer can be appropriately set depending on the purpose.

[0052] In one embodiment, the other protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0053] D-3. Hard coat layer In one embodiment, as described above, a hard coat layer 33 may be formed on the adhesive layer 20 side of the protective layer 32 of the polarizing plate 30. By providing a hard coat layer, the migration of light-absorbing compounds from the adhesive layer to the polarizing plate (substantially, the polarizer) can be further suppressed due to a synergistic effect with the effect of controlling the moisture permeability of the protective layer on the adhesive layer side. As a result, frame-shaped display defects can be further suppressed. The hard coat layer 33 is typically a cured layer of any suitable active energy ray (e.g., ultraviolet light, visible light, electron beam) curable resin. Examples of active energy ray curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, epoxy resins, etc. The hard coat layer may contain any suitable additives as needed. Typical examples of such additives include inorganic fine particles and / or organic fine particles. The thickness of the hard coat layer may be, for example, 1 μm to 10 μm, or for example, 3 μm to 7 μm.

[0054] E. Retardation layer As described above, the phase difference layer 40 typically has a circular polarization function or an elliptic polarization function. Furthermore, as described above, the phase difference layer 40 may be composed of a stretched resin film or a liquid crystal alignment solidification layer. The stretched resin film and the liquid crystal alignment solidification layer will be described below.

[0055] E-1. Stretched resin film E-1-1. Characteristics If the retardation layer has such a configuration, frame display defects can be suppressed in an optical laminate having an adhesive layer containing an absorbent compound by controlling the single transmittance of the polarizer or the moisture permeability of the protective layer on the adhesive layer side. In the present embodiment, the retardation layer is typically a single layer and can function as a so-called λ / 4 plate. In this case, Re(550) of the retardation layer 40 is preferably 100 nm to 200 nm, and the retardation layer 40 preferably satisfies the relationship of Re(450) < Re(550). Further, the angle formed by the slow axis of the retardation layer 40 and the absorption axis of the polarizer 31 is preferably 40° to 50°, more preferably 42° to 48°, still more preferably 44° to 46°, and particularly preferably about 45°.

[0056] Re(550) of the retardation layer 40 is more preferably 110 nm to 180 nm, still more preferably 120 nm to 160 nm, and particularly preferably 130 nm to 150 nm.

[0057] The retardation layer typically satisfies the relationship of Re(450) < Re(550) as described above, and preferably further satisfies the relationship of Re(550) < Re(650). That is, the retardation layer exhibits 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 layer is, for example, more than 0.5 and less than 1.0, preferably 0.7 to 0.95, more preferably 0.75 to 0.92, and still more preferably 0.8 to 0.9. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

[0058] Since the retardation layer has in-plane retardation as described above, it has a relationship of nx > ny. As long as the retardation layer has a relationship of nx > ny, it exhibits any appropriate refractive index characteristics. The refractive index characteristics of the retardation layer typically show a relationship of nx > ny ≥ nz. 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. The Nz coefficient of the retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and even more preferably 0.9 to 1.2. By satisfying such a relationship, when the optical laminate is used in an image display device, a very excellent reflected hue can be achieved.

[0059] The thickness of the retardation layer can be set so that it can function most appropriately as a λ / 4 plate. In other words, the thickness can be set so that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 15 μm to 60 μm, more preferably 20 μm to 55 μm, and most preferably 25 μm to 50 μm.

[0060] E-1-2. Constituent Material of Retardation Layer The retardation layer typically contains a resin containing at least one bonding group selected from the group consisting of carbonate bonds and ester bonds. In other words, the retardation layer contains a polycarbonate resin, a polyester resin, or a polyester carbonate resin (hereinafter, these may be collectively referred to as polycarbonate resins, etc.). Polycarbonate resins, etc. contain at least one structural unit selected from the group consisting of the structural unit represented by the following general formula (1) and / or the structural unit represented by the following general formula (2). These structural units are structural units derived from divalent oligofluorene and may hereinafter be referred to as oligofluorene structural units. Such polycarbonate resins, etc. have positive refractive index anisotropy.

Chemical Formula

Chemical Formula

[0061] The phase difference layer typically further contains an acrylic resin. The acrylic resin content is 0.5% by mass to 1.5% by mass. In this specification, a percentage or part in "mass" is synonymous with a percentage or part in "weight" units.

[0062] E-1-2-1. Polycarbonate resins, etc. <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 Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C4-C10 aryl group, a substituted or unsubstituted C1-C10 acyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C1-C10 aryloxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C10 vinyl group, a substituted or unsubstituted C1-C10 ethynyl group, a substituted sulfur atom, a substituted silicon atom, a halogen atom, a nitro group, or a cyano group. 4 ~R 9 They may be the same or different from each other, R 4 ~R 9 At least two adjacent groups may be bonded to each other to form a ring.

[0063] The content of oligofluorene structural units in polycarbonate resins, etc., is preferably 1% to 40% by mass, more preferably 10% to 35% by mass, even more preferably 15% to 30% by mass, and particularly preferably 18% to 25% by mass, relative to the total resin. If the content of oligofluorene structural units is too high, problems such as excessively high photoelastic coefficient, insufficient reliability, and insufficient phase difference expression may occur. Furthermore, because the proportion of oligofluorene structural units in the resin becomes high, the range of molecular design becomes narrower, and it may become difficult to improve the resin when modification is required. On the other hand, even if the desired inverse dispersion wavelength dependence can be obtained with a very small amount of oligofluorene structural units, in this case, the optical properties change sensitively in response to slight variations in the content of oligofluorene structural units, making it difficult to manufacture the resin so that various properties fall within a certain range.

[0064] Details of the oligofluorene structural units are described, for example, in International Publication No. 2015 / 159928, which is incorporated herein by reference.

[0065] <Other structural units> Polycarbonate resins and the like typically contain other structural units in addition to oligofluorene structural units. In one embodiment, the other structural units may preferably be derived from dihydroxy compounds or diester compounds. In order to achieve the desired inverse wavelength dispersion, it is necessary to incorporate structural units having positive intrinsic birefringence into the polymer structure along with oligofluorene structural units having negative intrinsic birefringence. Therefore, dihydroxy compounds or diester compounds that serve as raw materials for structural units having positive birefringence are even more preferred as other monomers for copolymerization.

[0066] Examples of copolymer monomers include compounds into which a structural unit containing an aromatic ring can be introduced, and compounds that do not incorporate a structural unit containing an aromatic ring, i.e., compounds composed of an aliphatic structure. Specific examples of compounds composed of the aforementioned aliphatic structure are listed below: Dihydroxy compounds of straight-chain aliphatic hydrocarbons such as 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; Dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol; and 1,2-cyclohexanediol. Examples of alicyclic hydrocarbon secondary and tertiary alcohols include dihydroxy compounds such as 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc.; 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2,6-decali Dihydroxy compounds, which are primary alcohols of alicyclic hydrocarbons, are exemplified by dihydroxy compounds derived from terpene compounds such as dimethyl dimethyl, 1,5-decalindimethanol, 2,3-decalindimethanol, 2,3-norbornanedimethanol, 2,5-norbornanedimethanol, 1,3-adamantanedimethanol, and limonene; oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and polypropylene glycol; dihydroxy compounds having a cyclic ether structure such as isosorbide; dihydroxy compounds having a cyclic acetal structure such as spiroglycol and dioxane glycol; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Specific examples of compounds into which the aforementioned aromatic ring-containing structural unit can be introduced are listed below: 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(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(4-hydroxyphenyl) 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'-dihydroxydiphenylsulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4, Aromatic bisphenol compounds such as 4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether; dihydroxy compounds having an ether group bonded to an aromatic group, such as 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;Aromatic dicarboxylic acids such as 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. Furthermore, while the aliphatic dicarboxylic acid and aromatic dicarboxylic acid components listed above can be used as raw materials for the polyester carbonate as dicarboxylic acids themselves, depending on the manufacturing method, dicarboxylic acid esters such as methyl esters and phenyl esters, or dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

[0067] As copolymer monomers, dihydroxy compounds having a fluorene ring, such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, which have been conventionally known as compounds having a structural unit with negative birefringence, as well as dicarboxylic acid compounds having a fluorene ring, can also be used in combination with oligofluorene compounds.

[0068] The resin used in the present invention preferably contains, among the structural units that can be introduced by the compound having the alicyclic structure, a structural unit represented by the following formula (3) as a copolymer component. [ka]

[0069] Spiroglycol can be used as a dihydroxy compound to which the structural unit of formula (3) can be introduced.

[0070] In the resin used in the present invention, it is preferable that the structural unit represented by formula (3) is contained in an amount of 5% by mass or more and 90% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more. If the content of the structural unit represented by formula (3) is above the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Furthermore, compatibility with acrylic resins is improved, and the transparency of the resulting resin composition can be further improved. In addition, since the polymerization reaction rate of spiroglycol is relatively slow, it is easier to control the polymerization reaction by keeping the content below the upper limit.

[0071] The resin used in the present invention preferably further contains a structural unit represented by the following formula (4) as a copolymer component. [ka]

[0072] Examples of dihydroxy compounds into which the structural unit represented by formula (4) can be introduced include isosorbide (ISB), isomannide, and isoidette, which are stereoisomers of each other. These may be used individually or in combination of two or more.

[0073] In the resin used in the present invention, it is preferable that the structural unit represented by formula (4) is contained in an amount of 5% by mass or more and 90% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, and particularly preferably 15% by mass or more. If the content of the structural unit represented by formula (4) is above the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Furthermore, since the structural unit represented by formula (4) has the characteristic of high water absorption, if the content of the structural unit represented by formula (4) is below the upper limit, the dimensional change of the molded article due to water absorption can be kept within an acceptable range.

[0074] The resin used in the present invention may further contain other structural units. Such structural units may be referred to as "other structural units." As monomers having other structural units, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, and 1,4-cyclohexanedicarboxylic acid (and their derivatives) are more preferably used, with 1,4-cyclohexanedimethanol and tricyclodecanedimethanol being particularly preferred. Resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, etc. Furthermore, since the polymerization reactivity of diester compounds is relatively low, it is preferable not to use diester compounds other than those containing oligofluorene structural units from the viewpoint of improving reaction efficiency.

[0075] The glass transition temperature (Tg) of the resin used in the present invention is preferably 110°C or higher and 160°C or lower. The upper limit is more preferably 155°C or lower, even more preferably 150°C or lower, and particularly preferably 145°C or lower. The lower limit is more preferably 120°C or higher, and particularly preferably 130°C or higher. If the glass transition temperature is outside the above range, the heat resistance tends to deteriorate, which may cause dimensional changes after film formation or worsen the reliability of the quality under the usage conditions of the phase difference film. On the other hand, if the glass transition temperature is excessively high, unevenness in film thickness may occur during film formation, the film may become brittle, its stretchability may deteriorate, and the transparency of the film may be impaired.

[0076] Details regarding the composition and manufacturing methods of polycarbonate resins, etc., are described, for example, in International Publication No. 2015 / 159928 (above). This description is incorporated herein by reference.

[0077] E-1-2-2. Acrylic resin Acrylic resins used are thermoplastic acrylic resins. Examples of monomers that form the structural units of acrylic resins 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)acroyloxyethyl succinate, 2-(meth)acroyloxyethyl maleate, 2-(meth)acroyloxyethyl 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, cyclododecyl acrylate. These may be used individually or in combination of two or more types. Forms using two or more monomers in combination 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., olefin monomers, vinyl monomers) may be used in combination.

[0078] The acrylic resin contains structural units derived from methyl methacrylate. The content of structural units derived from methyl methacrylate in the acrylic resin is preferably 70% by mass or more and 100% by mass or less. The lower limit is more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Within this range, excellent compatibility with the polycarbonate resin of the present invention can be obtained. As structural units other than methyl methacrylate, it is preferable to use methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene. Thermal stability can be improved by copolymerizing methyl acrylate. By using phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene, the refractive index of the acrylic resin can be adjusted, and by matching it to the refractive index of the resin to be combined with, the transparency of the resulting resin composition can be improved. By using such an acrylic resin, an inverse dispersion phase difference film with excellent stretchability and phase difference expression, and low haze can be obtained.

[0079] The weight-average molecular weight (Mw) of the acrylic resin is between 10,000 and 200,000. The lower limit is preferably 30,000 or higher, and particularly preferably 50,000 or higher. The upper limit is preferably 180,000 or lower, and particularly preferably 150,000 or lower. Within this molecular weight range, compatibility with polycarbonate resins is achieved, improving the transparency of the final phase difference film (phase difference layer) and significantly improving the stretchability during stretching. The above weight-average molecular weight is measured by GPC and is the molecular weight in polystyrene equivalent. Furthermore, from the viewpoint of compatibility, it is preferable that the acrylic resin substantially does not contain branched structures. The absence of branched structures can be confirmed by the unimodal GPC curve of the acrylic resin.

[0080] E-1-2-3. Blends of polycarbonate resins and acrylic resins Polycarbonate resins and acrylic resins are blended and used as a resin composition in a method for manufacturing a phase difference film (phase difference layer). The content of acrylic resin in the resin composition (and consequently the phase difference layer) is 0.5% by mass or more and 2.0% by mass or less, as described above. The lower limit is more preferably 0.6% by mass or more. The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by weight or less, even more preferably 0.9% by weight or less, and particularly preferably 0.8% by mass or less. In this way, by blending acrylic resin with polycarbonate resin in a very limited ratio, the stretchability and phase difference expression can be significantly increased. Furthermore, haze can be suppressed. Such effects are not theoretically clear and are unexpected excellent effects obtained through trial and error. Note that if the acrylic resin content is too low, the above effects may not be obtained. On the other hand, if the acrylic resin content is too high, haze may become high. Furthermore, the extensibility and phase difference characteristics are often insufficient or even decreased compared to the cases within the above range.

[0081] The resin composition may be further blended with synthetic resins such as aromatic polycarbonates, aliphatic polycarbonates, aromatic polyesters, aliphatic polyesters, polyamides, polystyrene, polyolefins, acrylics, amorphous polyolefins, ABS, AS, polylactic acid, polybutylene succinate, rubber, and combinations thereof, for the purpose of modifying properties such as mechanical properties and / or solvent resistance.

[0082] The resin composition may further contain additives. Specific examples of additives include heat stabilizers, antioxidants, catalyst deactivators, ultraviolet absorbers, light stabilizers, mold release agents, dyes and pigments, impact modifiers, antistatic agents, lubricants, plasticizers, compatibilizers, nucleating agents, flame retardants, inorganic fillers, and foaming agents. The types, number, combinations, and content of additives included in the resin composition can be appropriately determined depending on the purpose.

[0083] E-1-3. Method for forming a phase difference layer The phase difference layer is obtained by forming a film from the above resin composition and then stretching the film. Since the method for forming the phase difference layer (the method for stretching the resin film) can be based on conditions well known in the industry, a detailed explanation is omitted.

[0084] E-2. Liquid crystal alignment solidification layer If the phase difference layer has such a configuration, the optical laminate can be made significantly thinner. In this case, as described above, the phase difference layer may be a single layer, or it may have a two-layer structure consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer. In this specification, "alignment solidification layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer, and this alignment state is fixed. Note that "alignment solidification layer" is a concept that includes alignment hardened layers obtained by hardening liquid crystal monomers. In the phase difference layer, typically, rod-shaped liquid crystal compounds are aligned in the direction of the slow phase axis of the phase difference layer (homogenous orientation).

[0085] Examples of liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. Preferably, the liquid crystal compound is polymerizable. If the liquid crystal compound is polymerizable, its orientation can be fixed by polymerizing it after orientation. Here, the polymer formed by polymerization is non-liquid crystal. Therefore, the formed phase difference layer does not undergo transitions to liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which are characteristic of liquid crystal compounds. As a result, the phase difference layer becomes an extremely stable phase difference layer that is unaffected by temperature changes.

[0086] In one embodiment, the phase difference layer may be formed using a composition containing a polymerizable liquid crystal compound. In this specification, a polymerizable liquid crystal compound included in the composition means a compound that has polymerizable groups and is liquid crystalline. A polymerizable group means a group that participates in the polymerization reaction, and is preferably a photopolymerizable group. Here, a photopolymerizable group means a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator.

[0087] The mechanism by which the liquid crystalline properties of a liquid crystal compound are exhibited may be thermotropic or lyotropic. Furthermore, the liquid crystal phase may be composed of either a nematic or smectic liquid crystal. From the viewpoint of ease of manufacture, a thermotropic nematic liquid crystal is preferred.

[0088] The temperature range in which liquid crystal monomers exhibit liquid crystalline properties varies depending on the type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

[0089] E-2-1. Single Layer The characteristics of the liquid crystal alignment solidification layer when it is a single layer are the same as those described in Section E-1-1 for stretched resin films, except for the thickness. The thickness of the liquid crystal alignment solidification layer when it is a single layer can be, for example, 1.0 μm to 5.0 μm, or for example, 1.0 μm to 3.0 μm.

[0090] The phase difference layer of this embodiment is formed using, for example, a composition containing a liquid crystal compound represented by the following formula (1). L 1 -SP 1 -A 1 -D 3 -G 1 -D 1 -Ar-D 2 -G 2 -D 4 -A 2 -SP 2 -L 2 (1)

[0091] L 1 and L 2 Each of these independently represents a monovalent organic group, L 1 and L 2 At least one of them represents a polymerizable group. Any suitable monovalent organic group is included. 1 and L 2Examples of polymerizable groups represented by at least one of the following are radical polymerizable groups (groups capable of radical polymerization). Any suitable radical polymerizable group can be used. Preferably, it is an acryloyl group or a methacryloyl group. The acryloyl group is preferred from the viewpoint of faster polymerization and improved productivity. The methacryloyl group can also be used similarly as a polymerizable group for high birefringence liquid crystals.

[0092] SP 1 and SP 2 Each of these independently represents a single bond, a linear or branched alkylene group, or a divalent linking group in which one or more of the -CH2- groups constituting a linear or branched alkylene group having 1 to 14 carbon atoms are substituted with -O-. Preferred examples of linear or branched alkylene groups having 1 to 14 carbon atoms include methylene, ethylene, propylene, butylene, pentylene, and hexylene groups.

[0093] A 1 and A 2 Each of these independently represents an alicyclic hydrocarbon group or an aromatic ring substituent. 1 and A 2 Preferably, it is an aromatic ring substituent having 6 or more carbon atoms or a cycloalkylene ring having 6 or more carbon atoms.

[0094] D 1 , D 2 , D 3 and D 4 Each of these independently represents a single bond or a divalent linking group. Specifically, D 1 , D 2 , D 3 and D 4 These are single bonds, -O-CO-, -C(=S)O-, and -CR bonds. 1 R 2 -, -CR 1 R 2 -CR 3 R 4 -, -O-CR 1 R 2 -, -CR 1 R 2 -O-CR 3 R4 -,-CO-O-CR 1 R 2 -,-O-CO-CR 1 R 2 -,-CR 1 R 2 -O-CO-CR 3 R 4 -,-CR 1 R 2 -CO-O-CR 3 R 4 -,-NR 1 -CR 2 R 3 -,-or-CO-NR 1 -represents.However,D 1 、D 2 、D 3 andD 4 at least one of represents -O-CO-.Among them,D 3 is preferably -O-CO-,D 3 andD 4 being -O-CO- is more preferable.D 1 andD 2 are preferably single bonds.R 1 、R 2 、R 3 andR 4 each independently represents a hydrogen atom,a fluorine atom,or an alkyl group having 1 to 4 carbon atoms.

[0095] G 1 andG 2 each independently represents a single bond or an alicyclic hydrocarbon group.Specifically,G 1 andG 2 may represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms.Also,one or more of -CH2- constituting the alicyclic hydrocarbon group may be substituted with -O-,-S- or -NH-.G 1 andG 2 preferably represent a single bond.

[0096] Ar represents an aromatic hydrocarbon ring or an aromatic heterocycle. For example, Ar represents an aromatic ring selected from the group consisting of groups represented by the following formulas (Ar-1) to (Ar-6). In the following formulas (Ar-1) to (Ar-6), *1 is D 1 This represents the bond position with, and *2 is D 2 This indicates the connection point with [the other element]. [ka]

[0097] In formula (Ar-1), Q 1 represents N or CH, and Q 2 -S-, -O-, or -N(R 5 ) represents R 5 Y represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 1 This represents an unsubstituted or substituted aromatic hydrocarbon group having 6 to 12 carbon atoms, or an aromatic heterocyclic group having 3 to 12 carbon atoms.

[0098] In equations (Ar-1) to (Ar-6), Z 1 , Z 2 and Z 3 These are, independently, a hydrogen atom, a monovalent aliphatic hydrocarbon group with 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group with 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group with 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, and -NR. 6 R 7 , or -SR 8 Represents R 6 ~R 8 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Z 1 and Z 2 These elements may bond to each other to form a ring. The ring may be alicyclic, heterocyclic, or aromatic, and is preferably an aromatic ring. The formed ring may be substituted with substituents.

[0099] In equations (Ar-2) and (Ar-3), A 3 and A 4 These are -O- and -N(R) respectively, independently. 9R represents a group selected from the group consisting of -, -S-, and -CO-. 9 R represents a hydrogen atom or substituent. 9 The substituent shown is Y in the above formula (Ar-1). 1 Examples of substituents that may be present include the same ones as those that may be present.

[0100] In formula (Ar-2), X represents a hydrogen atom or an unsubstituted or substituted nonmetal atom of Group 14 to 16. Examples of Group 14 to 16 nonmetal atoms represented by X include oxygen, sulfur, unsubstituted or substituted nitrogen, and unsubstituted or substituted carbon atoms. The substituent is Y in formula (Ar-1) above. 1 Examples of substituents that may be present include the same ones as those that may be present.

[0101] In formula (Ar-3), D 5 and D 6 These are, independently, single bonds, -O-CO-, -C(=S)O-, and -CR bonds. 1 R 2 -, -CR 1 R 2 -CR 3 R 4 -, -O-CR 1 R 2 -, -CR 1 R 2 -O-CR 3 R 4 -,-CO-O-CR 1 R 2 -, -O-CO-CR 1 R 2 -, -CR 1 R 2 -O-CO-CR 3 R 4 -, -CR 1 R 2 -CO-O-CR 3 R 4 -, -NR 1 -CR 2 R 3 -, or -CO-NR 1 - represents R 1 , R 2 , R 3 and R4 This is as stated above.

[0102] In formula (Ar-3), SP 3 and SP 4 Each of these independently represents a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a divalent linking group in which one or more of the -CH2- groups constituting a linear or branched alkylene group having 1 to 12 carbon atoms are substituted with -O-, -S-, -NH-, -N(Q)-, or -CO-, where Q represents a polymerizable group.

[0103] In formula (Ar-3), L 3 and L 4 Each of these independently represents a monovalent organic group, L 3 and L 4 Furthermore, L in formula (1) above 1 and L 2 At least one of them represents a polymerizable group.

[0104] In formulas (Ar-4) to (Ar-6), Ax represents an organic group having 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulas (Ar-4) to (Ar-6), Ax preferably has an aromatic heterocycle, and more preferably has a benzothiazole ring. In formulas (Ar-4) to (Ar-6), Ay represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms which may be unsubstituted or substituted, or an organic group having 2 to 30 carbon atoms having at least one aromatic ring selected from the group consisting of aromatic hydrocarbon rings and aromatic heterocycles. In formulas (Ar-4) to (Ar-6), Ay preferably represents a hydrogen atom.

[0105] In equations (Ar-4) to (Ar-6), Q 3 Q represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, which may be unsubstituted or substituted. In formulas (Ar-4) to (Ar-6), Q 3 This preferably represents a hydrogen atom.

[0106] Among such Ar groups, preferred examples include those represented by the above formula (Ar-4) or (Ar-6).

[0107] Liquid crystal polymers and liquid crystal monomers may be used individually or in combination. Specific examples of liquid crystal compounds are described, for example, in Japanese Patent Publication No. 2006-163343, Japanese Patent Publication No. 2006-178389, and International Publication No. 2018 / 123551. The descriptions in these publications are incorporated herein by reference.

[0108] E-2-2. Two-layer structure consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer When the phase difference layer has a two-layer structure consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer from the polarizer side, the first liquid crystal alignment solidification layer can typically function as a λ / 2 plate, and the second liquid crystal alignment solidification layer can typically function as a λ / 4 plate. Specifically, the Re(550) of the first liquid crystal alignment solidification layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm; the Re(550) of the second liquid crystal alignment solidification layer is as described in section E-1-1 with respect to the stretched film of the resin film. The thickness of the first liquid crystal alignment solidification layer can be adjusted to obtain a desired in-plane phase difference for the λ / 2 plate. Specifically, its thickness may be, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment solidification layer can be adjusted to obtain a desired in-plane phase difference for the λ / 4 plate. Specifically, its thickness may be, for example, 1.0 μm to 2.5 μm. In this embodiment, the angle between the slow axis of the first liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably 14° to 16°; the angle between the slow axis of the second liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably 74° to 76°. Note that the arrangement order of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may be reversed, and the angles between the slow axis of the first liquid crystal alignment solidification layer and the absorption axis of the polarizer and the angles between the slow axis of the second liquid crystal alignment solidification layer and the absorption axis of the polarizer may be reversed. The first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer may exhibit inverse dispersion wavelength characteristics in which the phase difference value increases with the wavelength of the measurement light, or they may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with the wavelength of the measurement light, or they may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes with the wavelength of the measurement light.

[0109] The phase difference layer of this embodiment is formed, for example, using a composition containing any suitable liquid crystal monomer. Examples of liquid crystal monomers that can be used include polymerizable mesogenic compounds described in JP 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US4388453), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445, etc. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767. As the liquid crystal monomer, nematic liquid crystal monomers are preferred.

[0110] F. Another phase difference layer Another phase difference layer 50 may be a so-called positive C plate, as described above, whose refractive index characteristics exhibit the relationship nz>nx=ny. By using a positive C plate as another phase difference layer, oblique reflections can be effectively prevented, and the anti-reflective function can be widened to a wider viewing angle. In this case, the phase difference Rth(550) in the thickness direction of the other phase difference layer is preferably -50nm to -300nm, more preferably -70nm to -250nm, even more preferably -90nm to -200nm, and particularly preferably -100nm to -180nm. Here, "nx=ny" includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the other phase difference layer may be less than 10nm.

[0111] Another phase difference layer can be formed from any suitable material. Preferably, the other phase difference layer consists of a film containing a liquid crystal material fixed in a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the phase difference layer are described in paragraphs

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642. In this case, the thickness of the other phase difference layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0112] G. Image display device The optical laminates described in items A to F above can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such optical laminates. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical laminate described in items A to F above on its viewing side. The optical laminate is arranged so that its front panel faces the viewing side. [Examples]

[0113] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0114] [Abbreviations for compounds] The abbreviations for the compounds used in the following manufacturing examples are as follows: • BPFM: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane It was synthesized by the method described in Japanese Patent Publication No. 2015-25111. [ka] • ISB: Isosorbide [manufactured by Rocket Fleuret] • SPG: Spiroglycol [Manufactured by Mitsubishi Gas Chemical Company, Inc.] • DPC: Diphenyl carbonate [manufactured by Mitsubishi Chemical Corporation]

[0115] [Manufacturing Example 1: Fabrication of the phase difference film constituting the phase difference layer] Polymerization was carried out using a batch polymerization apparatus consisting of two vertical stirred reactors equipped with stirring blades and reflux condensers. The mixture consisted of 30.31 parts by mass (0.047 mol) of BPFM, 39.94 parts by mass (0.273 mol) of ISB, 30.20 parts by mass (0.099 mol) of SPG, 69.67 parts by mass (0.325 mol) of DPC, and 7.88 × 10⁻¹⁶ calcium acetate monohydrate as a catalyst. -4 Part of mass (4.47×10 -6 A mol (mol) of polymer was added. After purging the reactor with nitrogen under reduced pressure, the reactor was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the pressure to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was directed to a reflux condenser at 110°C, and the monomer components contained in the phenol vapor were returned to the reactor. The uncondensed phenol vapor was directed to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and then the oligomerized reaction mixture in the first reactor was transferred to the second reactor. Next, heating and depressurization were started in the second reactor, and the internal temperature reached 240°C and the pressure 20 kPa in 40 minutes. After that, polymerization was continued while further reducing the pressure until the required stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate was extruded into water. The strands were then cut to obtain pellets. This resin is called "PC1". The ratio of structural units derived from each monomer is BPFM / ISB / SPG / DPC = 21.5 / 39.4 / 30.0 / 9.1 mass%. The reduced viscosity of PC1 is 0.46 dL / g, Mw is 48,000, and refractive index n D The coefficient of thermal energy is 1.526, the melt viscosity is 2480 Pa·s, the glass transition temperature is 139°C, and the photoelastic modulus is 9 × 10⁻⁶. -12 [m 2 The wavelength dispersion Re(450) / Re(550) was 0.85.

[0116] Using Dianaal BR80 (manufactured by Mitsubishi Chemical Corporation) as the acrylic resin, the obtained polyester carbonate was extruded and kneaded. A mixture of polycarbonate pellets (99.5 parts by mass) and BR80 powder (0.5 parts by mass) was fed into a twin-screw extruder TEX30HSS manufactured by Japan Steel Works Ltd. using a quantitative feeder. The extruder cylinder temperature was set to 250°C, and extrusion was performed at a processing rate of 12 kg / hr and a screw rotation speed of 120 rpm. The extruder was also equipped with a vacuum vent, and the molten resin was extruded while defolatting under reduced pressure. The resin composition pellets obtained in this manner were vacuum-dried at 100°C for more than 6 hours. Then, a long, unstretched film with a length of 3 m, a width of 200 mm, and a thickness of 100 μm was produced using a film-making apparatus equipped with a single-screw extruder (manufactured by Isuzu Chemical Machinery Co., Ltd., screw diameter 25 mm, cylinder setting temperature: 250°C), a T-die (width 300 mm, setting temperature: 220°C), a chill roll (setting temperature: 120~130°C), and a winding machine. This long, unstretched film was stretched at a stretching temperature Tg and a stretching ratio of 2.7 times to obtain a phase difference film R1 with a thickness of 37 μm. The Re(550) of the obtained phase difference film R1 was 141 nm, the Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12.

[0117] [Manufacturing Example 2: Fabrication of the phase difference film constituting the phase difference layer] A phase difference film R2 was obtained in the same manner as in Manufacturing Example 1, except that the thickness of the long unstretched film was 130 μm and the thickness of the phase difference film was 48 μm. The Re(550) of the obtained phase difference film R2 was 141 nm, the Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12.

[0118] [Manufacturing Example 3: Fabrication of the first liquid crystal alignment solidification layer and the second liquid crystal alignment solidification layer constituting the phase difference layer] A liquid crystal composition (coating solution) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (BASF: trade name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film (38 μm thick) was rubbed using a rubbing cloth to perform an orientation treatment. The orientation direction was set to 15° from the viewing side relative to the direction of the absorption axis of the polarizing film when bonded to a polarizing plate. The liquid crystal coating solution was applied to this orientation-treated surface using a bar coater and heated and dried at 90°C for 2 minutes to orient the liquid crystal compound. The liquid crystal layer thus formed was irradiated with 1 mJ / cm2 of light using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal orientation solidified layer A on the PET film. The thickness of the liquid crystal orientation solidified layer A was 2.5 μm, and the in-plane phase difference Re(550) was 270 nm. Furthermore, the liquid crystal orientation solidified layer A had a refractive index distribution of nx>ny=nz. A liquid crystal alignment solidification layer B was formed on a PET film in the same manner as described above, except that the coating thickness was changed and the orientation direction was set to 75° from the viewing side relative to the direction of the absorption axis of the polarizing film. The thickness of the liquid crystal alignment solidification layer B was 1.5 μm, and the in-plane phase difference Re(550) was 140 nm. Furthermore, the liquid crystal alignment solidification layer B had a refractive index distribution of nx>ny=nz. Liquid crystal alignment solidification layer A and liquid crystal alignment solidification layer B are transferred to the polarizing plate in this order in the optical laminate.

[0119] [Manufacturing Example 4: Fabrication of a liquid crystal alignment solidification layer that constitutes another phase difference layer] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (I) (the numbers 65 and 35 in the formula indicate the mole percent of monomer units and are conveniently represented as a block polymer: weight-average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a vertically aligned PET substrate using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. By irradiating this liquid crystal layer with ultraviolet light and curing the liquid crystal layer, another phase difference layer (thickness 3 μm) exhibiting refractive index characteristics nz>nx=ny was formed on the substrate. This other phase difference layer is transferred to the phase difference layer in the optical laminate. [ka]

[0120] [Manufacturing Example 5: Fabrication of Polarizing Plates] (Fabrication of polarizers) As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be the desired value (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the material was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on a resin substrate, and a polarizing plate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.3%.

[0121] (Fabrication of polarizing plates) An HC-TAC film was laminated to the surface of the obtained polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. The HC-TAC film is a triacetylcellulose (TAC) film (25 μm thick) with an HC layer (7 μm thick) formed on it, and it was laminated so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off to obtain a polarizer plate P1 having the structure of HC layer / TAC film (protective layer) / polarizer. The moisture permeability of the protective layer was 400 g / m². 2 It was 24 hours.

[0122] [Manufacturing Example 6: Fabrication of Polarizing Plates] A polarizing plate P2 having the configuration of HC layer / COP film (protective layer) / polarizer was obtained in the same manner as in Manufacturing Example 5, except that the transmittance Ts of the polarizer was set to 43.0% and an HC-COP film was used instead of an HC-TAC film. The HC-COP film is a film in which an HC layer (thickness 2 μm) is formed on a cycloolefin resin (COP) film (thickness 25 μm), and it was laminated so that the COP film was on the polarizer side. The moisture permeability of the protective layer was 20 g / m². 2 It was 24 hours.

[0123] [Manufacturing Example 7: Fabrication of Polarizing Plates] A polarizing plate P3 having the configuration of HC layer / COP film (protective layer) / polarizer was obtained in the same manner as in Manufacturing Example 6, except that the transmittance Ts of the polarizer alone was set to 44.0%.

[0124] [Manufacturing Example 8: Fabrication of Polarizing Plates] A polarizing plate P4 having the configuration of HC layer / TAC film (protective layer) / polarizer was obtained in the same manner as in Manufacturing Example 5, except that the transmittance Ts of the polarizer alone was set to 42.0%.

[0125] [Manufacturing Example 9: Fabrication of Polarizing Plates] A polarizing plate P5 having the configuration of HC layer / acrylic film (protective layer) / polarizer was obtained in the same manner as in Manufacturing Example 5, except that the transmittance Ts of the polarizer was set to 42.5% and an acrylic film (thickness 40 μm) was used instead of the HC-TAC film. The moisture permeability of the protective layer was 70 g / m². 2 It was 24 hours.

[0126] [Manufacturing Example 10: Fabrication of Polarizing Plates] (Fabrication of polarizers) A 12 μm thick polarizer was fabricated by uniaxially stretching a 30 μm thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") in the longitudinal direction using a roll stretching machine to 5.9 times its length, while simultaneously subjecting it to swelling, dyeing, crosslinking, and washing treatments, and finally drying. The transmittance Ts of the polarizer was 43.5%. Specifically, the swelling treatment involved stretching the material 2.2 times while treating it with pure water at 20°C. Next, the dyeing treatment involved stretching the material 1.4 times while treating it in an aqueous solution at 30°C with an iodine-to-potassium iodide weight ratio of 1:7, where the iodine concentration was adjusted so that the resulting polarizer's single-component transmittance was 43.5%. Furthermore, the cross-linking treatment employed a two-stage process. In the first stage, the material was stretched 1.2 times while treating it in an aqueous solution of boric acid and potassium iodide at 40°C. The boric acid content of the aqueous solution for the first stage was 5.0% by weight, and the potassium iodide content was 3.0% by weight. In the second stage, the material was stretched 1.6 times while treating it in an aqueous solution of boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution for the second stage was 4.3% by weight, and the potassium iodide content was 5.0% by weight. Furthermore, the washing treatment was performed with an aqueous potassium iodide solution at 20°C. The potassium iodide content of the washing solution was 2.6% by weight. Finally, the polarizer was obtained by drying at 70°C for 5 minutes.

[0127] (Fabrication of polarizing plates) An HC-TAC film was bonded to one side of the polarizer via a polyvinyl alcohol-based adhesive, and a TAC film (25 μm thick) was bonded to the other side via a polyvinyl alcohol-based adhesive to obtain a polarizing plate P6 having the structure of HC layer / TAC film (protective layer) / polarizer / TAC film (protective layer).

[0128] [Manufacturing Example 11: Preparation of Photocurable Adhesive Constituting the Adhesive Layer] A monomer mixture containing 70 parts by weight of 2-ethylhexyl acrylate (2EHA), 15 parts by weight of 2-hydroxyethyl acrylate (2HEA), and 15 parts by weight of methyl acrylate (MA) was charged. Furthermore, 0.5 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator was charged to 100 parts of the monomer mixture (solids) together with 250 parts by weight of ethyl acetate, and the mixture was stirred for 1 hour under a nitrogen atmosphere at 23°C, followed by nitrogen purging. The mixture was then reacted at 56°C for 5 hours, and then at 70°C for 3 hours to prepare a solution of acrylic-based polymer. To the above-obtained acrylic-based polymer solution, the following post-addition components were added per 100 parts of the base polymer and homogeneously mixed to prepare a photocurable adhesive. (Post-added ingredients) Dipentaerythritol hexaacrylate as a polyfunctional compound (photocuring agent): 2 parts Polypropylene glycol diacrylate (product name: APG400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., polypropylene glycol #400 (n=7) diacrylate, functional group equivalent 268 g / eq) as a polyfunctional compound (photocuring agent): 3 parts Photopolymerization initiator (4-methylbenzophenone, absorption maximum wavelength 280 nm): 0.2 parts (Preparation of adhesive sheets) A photocurable adhesive was applied to a release liner (a 75 μm thick polyethylene terephthalate (PET) film with a silicone-based release layer on its surface: "Diafoil MRF75" manufactured by Mitsubishi Chemical Corporation), heated at 100°C for 3 minutes to remove the solvent, and then the same release liner was bonded to the surface. The resulting laminate was aged at 25°C for 3 days to obtain an adhesive sheet with release liners temporarily attached to both sides. The adhesive layer was in a semi-cured state.

[0129] [Example 1] In Manufacturing Example 5, the polarizer surface of the polarizer plate P1 was bonded to the phase difference film R1 obtained in Manufacturing Example 1 via an acrylic adhesive (5 μm thick). Here, the polarizer plate P1 and the phase difference layer (phase difference film) R1 were bonded so that the absorption axis of the polarizer and the slow phase axis of the phase difference film formed a 45° angle. Furthermore, an adhesive layer was transferred from the adhesive sheet obtained in Manufacturing Example 11 to the side of the polarizer plate opposite the phase difference film, and a front plate (1.5 mm thick glass plate) was bonded via this adhesive layer. Specifically, the front plate and the polarizer plate / phase difference film (phase difference layer) were vacuum laminated via the adhesive layer, and then ultraviolet light with an integrated light intensity of 6000 mJ / cm² was applied from the front plate side. 2 The semi-cured adhesive layer was crosslinked (cured) by irradiation. The thickness of the cured adhesive layer was 150 μm. Finally, an acrylic adhesive layer (thickness 15 μm) was provided on the opposite side of the polarizer of the phase difference film to form another adhesive layer. A release liner was temporarily attached to the surface of this other adhesive layer. In this way, an optical laminate having the configuration of front plate / adhesive layer / HC layer / protective layer / polarizer / phase difference layer / another adhesive layer / release liner was obtained. The obtained optical laminate was subjected to the evaluation of the "frame-shaped display defect" described below. The results are shown in Table 1.

[0130] (Frame-shaped display defect) The obtained optical laminates were aged for 24 hours (25°C) after the adhesive layer cured. The aged optical laminates were subjected to a humidification endurance test at 60°C and 90%RH for 24 hours, and then to a humidification endurance test at 60°C and 90%RH for 72 hours. After aging (initial), after the 24-hour test, and after the 72-hour test, the optical laminates were exposed to sunlight, and the presence or absence of frame-shaped display defects was visually confirmed. Furthermore, the presence or absence of frame-shaped display defects was confirmed using a multi-angle variable automatic measuring spectrophotometer (Agilent Technologies, product name "CARY7000UMS"). When checking for frame-shaped display defects with the CARY7000UMS, the incident angle of the light source and the receiving angle of the light receiver were set to 50°. In addition, samples with frame-shaped display defects were irradiated with P-polarized and S-polarized light, respectively, and if there was a difference in the reflection spectra of the P-polarized and S-polarized light, the presence of a frame-shaped display defect was confirmed.

[0131] [Examples 2-5, Comparative Examples 1-2] An optical laminate was fabricated in the same manner as in Example 1, except that the polarizing plate and phase difference film (phase difference layer) were combined as shown in Table 1. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0132] [Table 1]

[0133] [evaluation] As is clear from Table 1, according to the embodiments of the present invention, frame-shaped display defects can be prevented in an optical laminate including an adhesive layer containing a specific light-absorbing compound. [Industrial applicability]

[0134] The optical laminate of the present invention can be suitably used in image display devices (typically liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0135] 10 Front plate 20 Adhesive layer 30 Polarizing plates 31 Polarizer 32 Protective layer 33 Hard Court Layer 40 Retardation layer 50 Another phase difference layer 100 Optical laminate

Claims

[Claim 1] It has a front panel, an adhesive layer, a polarizing plate, and a phase difference layer in this order. The polarizing plate includes a polarizer and a protective layer disposed on the adhesive layer side of the polarizer. The adhesive layer is composed of a photocurable adhesive containing a compound whose absorption maximum wavelength is 200 nm to 300 nm. The polarizer has a single-unit transmittance of 43.3% or more, or the protective layer has a moisture permeability of 100 g / cm³. ２ - Less than 24 hours Optical laminate.

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