JP2023128380A - Optical laminated body and image display device using the same - Google Patents

Abstract

To provide an optical laminated body in which frame-like display defects are suppressed.SOLUTION: An optical laminated body according to an embodiment of the present invention includes a front plate, 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 an adhesive layer side of the polarizer. The adhesive layer is composed of a photocurable adhesive containing a compound having a maximum absorption wavelength at 200nm to 300nm. A single transmittance of the polarizer is 43.3% or more. Alternatively, moisture permeability of the protective layer is 100 g/cm2 24hr or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical laminate and an image display device using the optical laminate.

In recent years, image display devices typified by liquid crystal display devices and electroluminescent (EL) display devices (eg, organic EL display devices and inorganic EL display devices) have rapidly become popular. Polarizing plates and retardation plates are typically used in image display devices. The polarizing plate and the retardation plate may be integrated with the front plate via an adhesive layer to form an optical laminate. However, when such an optical laminate is 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) that is visible due to reflection occurs. ) may occur.

JP2020-64290A

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to provide an optical laminate in which frame-like display defects are suppressed.

The optical laminate according to the embodiment of the present invention includes a front plate, an adhesive layer, a polarizing plate, and a retardation 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 having a maximum absorption wavelength of 200 nm to 300 nm. The single transmittance of the polarizer is 43.3% or more. Alternatively, the moisture permeability of the protective layer is 100 g/cm ² ·24 hr or less.
In one embodiment, the compound having a maximum absorption wavelength of 200 nm to 300 nm is a benzophenone compound.
In one embodiment, the polarizer has a thickness of 10 μm or less and an iodine concentration of 10% by weight 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 made of a stretched resin film, and its Re (550) is 100 nm to 200 nm, satisfying the relationship Re (450) < Re (550), The angle between 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 includes another retardation layer having a refractive index characteristic of nz>nx=ny on the opposite side of the retardation layer from the polarizing plate.
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 optical laminate described above.

According to the embodiments of the present invention, it is possible to realize an optical laminate in which frame-like display defects are suppressed.

FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention.

Hereinafter, typical embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., slow axis direction), and "ny" is the direction perpendicular to the slow axis in the plane (i.e., fast axis direction) "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" is the in-plane retardation of the film measured with light having a wavelength of λ nm at 23°C. For example, "Re(550)" is the in-plane retardation of the film measured with light having a wavelength of 550 nm at 23°C. Re(λ) is determined by the formula: Re=(nx−ny)×d, where d (nm) is the thickness of the film.
(3) Phase difference in thickness direction (Rth)
"Rth (λ)" is the retardation in the thickness direction of the film measured with light having a wavelength of λ nm at 23°C. For example, "Rth (550)" is the retardation in the thickness direction of the film measured with light having a wavelength of 550 nm at 23°C. Rth (λ) is determined by the formula: Rth=(nx-nz)×d, where d (nm) is the thickness of the film.
(4) Nz coefficient The Nz coefficient is determined by Nz=Rth/Re.
(5) Angle When an angle is referred to herein, unless otherwise specified, the angle includes angles in both clockwise and counterclockwise directions.

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

In the embodiment of the present invention, the adhesive layer 20 is made of a photocurable adhesive containing a compound having a maximum absorption wavelength of 200 nm to 300 nm. Further, the single transmittance of the polarizer 31 is 43.3% or more, or the moisture permeability of the protective layer 32 is 100 g/cm ² ·24 hr or less. If the single transmittance of the polarizer or the moisture permeability of the protective layer is within such a range, frame-like display defects can be suppressed in the optical laminate. More details are as follows. A problem in which frame-shaped display defects occur when an optical laminate in which the front plate is integrated with a polarizing plate etc. via an adhesive layer is exposed to sunlight after being placed in a high temperature and high humidity environment. was newly recognized. As a result of intensive studies on frame-like display defects, the inventors of the present invention estimated that frame-like display defects are caused by local anisotropic reflection of a polarizing plate. The inventors of the present invention further investigated the frame display defect based on the above estimation, and found that the cause of the defect is in the adhesive layer, and that when the adhesive layer contains a compound with a maximum absorption wavelength of 200 nm to 300 nm. It has been found that a frame-like display defect occurs. As a result of further studies based on this knowledge, the present inventors found that by controlling the single transmittance of the polarizer of the polarizing plate or the moisture permeability of the protective layer within a predetermined range, the migration of the compound and/or non-uniform It was discovered that the distribution was suppressed, and as a result, frame-like display defects were suppressed, and the present invention was completed. That is, the embodiments of the present invention solve a newly discovered problem in an optical laminate having a specific configuration, and the effect is unexpectedly excellent. Hereinafter, a "compound having a maximum absorption wavelength of 200 nm to 300 nm" may be referred to as a "light-absorbing compound" for convenience.

The retardation layer 40 typically has a circular polarization function or an elliptical polarization function. With such a configuration, an optical laminate having excellent antireflection properties can be obtained. In one embodiment, the retardation layer 40 is made of a stretched resin film. In this case, the retardation layer 40 is typically a single layer. In another embodiment, the retardation layer 40 is an alignment fixed layer of a liquid crystal compound (hereinafter sometimes referred to as a liquid crystal alignment fixed layer). In this case, the retardation layer 40 may be a single layer, or may have a two-layer structure of a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer. Details of the retardation layer 40 will be described later in Section E.

In one embodiment, the optical laminate may further include another retardation layer 50 on the opposite side of the retardation layer 40 to the polarizing plate 30. Another retardation layer 50 typically exhibits a refractive index characteristic of nz>nx=ny. By providing such another retardation layer, reflection in oblique directions can be effectively prevented, and the antireflection function can provide a wide viewing angle.

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, it is possible to better suppress the transfer of the light-absorbing compound from the adhesive layer to the polarizing plate (substantially, the polarizer). As a result, frame-like display defects can be suppressed even better.

Practically, the optical laminate has another adhesive layer (not shown) as the outermost layer on the side opposite to the front plate 10, so that it can be attached to an image display cell. In this case, it is preferable that a release liner is temporarily attached to the surface of the other pressure-sensitive adhesive layer until the optical laminate is used. Temporarily attaching a release liner protects another adhesive layer and enables roll formation of the optical laminate.

Hereinafter, the constituent elements of the optical laminate will be explained.

B. Front Board As the front board 10, any appropriate film or board may be employed depending on the purpose. For example, the front plate may be made of glass or resin. The light transmittance of the front plate at a wavelength of 550 nm is preferably 85% or more. The refractive index of the front plate at a wavelength of 550 nm is preferably 1.4 to 1.65.

Any suitable structure that can be used as a front plate of an image display device may be adopted as the glass plate. The thickness of the glass plate is, for example, 1 mm to 10 mm. By using a glass plate as the front plate, an optical laminate having extremely excellent mechanical strength and surface hardness can be obtained. Classified by composition, examples of the glass include soda lime glass, boric acid glass, aluminosilicate glass, and quartz glass. Furthermore, according to classification based on alkali components, alkali-free glass and low-alkali glass can be mentioned. The content of alkali metal components (eg, Na ₂ O, K ₂ O, Li ₂ O) in the glass is preferably 15% by weight or less, more preferably 10% by weight or less. The density of the glass is preferably 2.3 g/cm ³ to 3.0 g/cm ³ , more preferably 2.3 g/cm ³ to 2.7 g/cm ³ . If the density of the glass is within this range, it is possible to reduce the weight of the optical laminate.

Any suitable configuration that can be used as a front plate of an image display device may be adopted as the resin plate. Examples of the material constituting 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 plate, it is possible to achieve a surface hardness that poses no problem in practical use, and to achieve a reduction in weight compared to a glass plate. Furthermore, low power consumption can be achieved by using a resin that is more transparent than glass.

C. Adhesive Layer As described above, the adhesive layer is composed of a photocurable adhesive containing a compound (light-absorbing compound) having a maximum absorption wavelength of 200 nm to 300 nm. This will be explained in detail below.

C-1. Properties of 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 still more preferably -13°C or higher. When the glass transition temperature is within this range, it is possible to realize an adhesive layer having excellent impact resistance.

The peak top value of the loss tangent tan δ (that is, tan δ at the glass transition temperature) of the adhesive layer is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. , particularly preferably 1.75 or more. On the other hand, the upper limit of the peak top value of tan δ is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. If the peak top value of tan δ is in this range, the adhesive layer exhibits appropriate deformation behavior (viscoelastic behavior), so it can be used, for example, when irregularly shaped parts such as through holes are formed on the polarizing plate. , gaps are less likely to be formed when filling the irregularly shaped part.

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

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, particularly preferably 100 μm to 200 μm.

C-2. Photocurable adhesive C-2-1. Properties of photocurable adhesive The storage 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, more preferably 8.0 × 10 ³ Pa to 3.0 × 10 ⁵ Pa. If the storage modulus of the photocurable adhesive after curing is within this range, the gel elasticity of the adhesive layer will be low and the residual stress will be small.

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 after curing of the photocurable adhesive is within such a range, the front plate and the polarizing plate can be firmly fixed to each other. The gel fraction can be determined as the insoluble content in a solvent such as ethyl acetate. Specifically, the gel fraction is the weight fraction (unit: weight %) of insoluble components after immersing the adhesive constituting the adhesive layer in ethyl acetate at 23°C for 7 days relative to the sample before immersion. It is required as. The gel fraction can be adjusted by appropriately setting the type, combination and amount of monomer components constituting the base polymer of the adhesive, and the type and amount of the crosslinking agent.

C-2-2. Constituent materials of photocurable adhesive The photocurable adhesive may be any suitable photocurable adhesive (in this section, it may be simply referred to as an adhesive composition) as long as it has the above characteristics. ) can be used. Examples of the base polymer of the adhesive composition include (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate/vinyl chloride copolymer, modified polyolefin, epoxy polymer, fluorine polymer, Examples include rubber polymers such as natural rubber and synthetic rubber. Preferably, it is a (meth)acrylic adhesive composition containing a (meth)acrylic polymer as a base polymer. This is because it has excellent optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness, and adhesiveness, and is also excellent in weather resistance, heat resistance, and the like. In this specification, "(meth)acrylic" means acrylic and/or methacryl.

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

The alkyl (meth)acrylate is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, 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. can be used in a proportion of

The (meth)acrylic base polymer may contain a monomer component copolymerizable with an alkyl (meth)acrylate (hereinafter referred to as a copolymerizable monomer). Examples of copolymerizable monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, nitrogen atom-containing monomers, cyclization polymerizable 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, and 8-hydroxyoctyl ( Examples thereof include meth)acrylate, 10-hydroxydecyl(meth)acrylate, 12-hydroxylauryl(meth)acrylate, and (4-hydroxymethylcyclohexyl)-methylacrylate. 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, Examples include N-diethyl (meth)acrylamide and N-vinylpyrrolidone. Examples of the cyclization polymerizable monomer include alkoxyalkyl acrylate. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. The type, number, combination, amount, etc. of copolymerizable monomers can be appropriately set depending on the purpose.

Preferred combinations of monomer components include, for example, 2-ethylhexyl (meth)acrylate/methyl (meth)acrylate/2-hydroxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate/isobornyl (meth)acrylate//methyl (meth)acrylate. ) acrylate/2-hydroxyethyl (meth)acrylate, or butyl (meth)acrylate/cyclohexyl (meth)acrylate/stearyl (meth)acrylate/4-hydroxybutyl (meth)acrylate/N-vinylpyrrolidone.

C-2-2-2. Light Absorbing Compound A light absorbing compound can typically function as a photoinitiator. In an optical laminate having an adhesive layer containing such a compound, the effects of the embodiments of the present invention are remarkable. Specifically, even when the adhesive layer contains such a compound, it is possible to realize an optical laminate in which frame-like display defects are suppressed. Examples of such compounds include benzophenone compounds, anthraquinone compounds, and phenanthrenequinone compounds. Preferably, it is a benzophenone compound. When the adhesive layer contains a benzophenone compound, the effects of the embodiments of the present invention become even more remarkable. Examples of benzophenone compounds include benzophenone, methylbenzophenone, trimethylbenzophenone, methyl benzoylbenzoate, 4,4'-bis(diethylamino)benzophenone, methyl-o-benzoylbenzoate, [4-(methylphenylthio)phenyl]- Examples include phenylmethane and 2,2-dimethoxy-2-phenyl acetophenone. The benzophenone compounds may be used alone or in combination.

The light-absorbing compound is contained in the adhesive composition at a ratio of preferably 0.01 part to 0.5 part by weight, more preferably 0.01 part to 0.1 part by weight, based on 100 parts by weight of the base polymer. can be done.

C-2-2-3. Other Components of the Adhesive Composition The adhesive composition (photocurable adhesive) may contain a thermal polymerization initiator and a silane coupling agent in addition to the above-mentioned base polymer and light-absorbing compound.

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 is added to the adhesive composition at a ratio of preferably 0.01 part to 0.5 part by weight, more preferably 0.01 part to 0.1 part by weight, based on 100 parts by weight of the base polymer. may be contained in

Any suitable silane coupling agent may be used as the silane coupling agent. By using a silane coupling agent, the adhesive strength of the photocurable adhesive can be adjusted. The content of the silane coupling agent in the adhesive composition is preferably 0.01 parts by weight to 5 parts by weight, more preferably 0.03 parts by weight to 2 parts by weight, based on 100 parts by weight of the base polymer. be.

The adhesive composition (photocurable adhesive) may further contain an oligomer and/or a polyfunctional compound. Any suitable oligomer can be used as the oligomer. By using an oligomer, the viscoelasticity (therefore, fluidity and workability) and adhesive strength of the photocurable adhesive can be adjusted. The oligomer is preferably a (meth)acrylic oligomer. (Meth)acrylic oligomers may have excellent compatibility with the base polymer. The weight average molecular weight of the oligomer is preferably about 1,000 to 30,000, more preferably 1,500 to 10,000, and still more preferably 2,000 to 8,000. When the weight average molecular weight of the oligomer is within this range, excellent adhesive strength and adhesive retention can be achieved. Examples of the polyfunctional compound include compounds containing two or more polymerizable functional groups (ethylenic unsaturated groups) having an unsaturated double bond in one molecule. The polyfunctional compound is typically a photopolymerizable polyfunctional compound. As the polyfunctional compound, polyfunctional (meth)acrylate is preferred because it can be easily copolymerized with the monomer component of the (meth)acrylic polymer. By using a polyfunctional compound, an appropriate crosslinked structure can be introduced into the resulting adhesive layer. As a result, the front plate and the polarizing plate can be firmly fixed to each other, and an adhesive layer having excellent impact resistance and deformability can be realized. The type, number, combination, blending amount, etc. of oligomers and polyfunctional compounds can be appropriately set depending on the purpose.

The adhesive composition (photocurable adhesive) may further contain any suitable additive depending on the purpose. Examples of additives include antioxidants, antistatic agents, rework improvers, colorants, pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, and aging agents. Examples include inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, conductive agents, inorganic or organic fillers, metal powders, particles, and foils. Further, within a controllable range, a redox system may be employed in which a reducing agent is added. The type, number, combination, amount, etc. of additives can be appropriately set depending on the purpose.

C-3. Method for Forming Adhesive Layer The adhesive layer can be semi-cured by thermal polymerization and then finally cured by photopolymerization. Therefore, the light-absorbing compound described above can function not only as a photopolymerization initiator but also as a photocrosslinking agent. In one embodiment, a front plate and a polarizing plate may be laminated via a semi-cured adhesive layer. With such a configuration, for example, when an irregularly shaped part such as a through hole is formed on the polarizing plate, the irregularly shaped part can be filled without any gaps.

D. Polarizing plate D-1. Polarizer As the polarizer 31, any suitable polarizer may be employed. For example, the resin film forming the polarizer may be a single layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of single-layer resin films include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films. Examples include those that have been dyed with dichroic substances such as iodine and dichroic dyes and stretched, and polyene-based oriented films such as dehydrated PVA and dehydrochloric acid treated polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because it has excellent optical properties.

The above-mentioned staining with iodine is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing process or may be performed while dyeing. Alternatively, it may be dyed after being stretched. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing a PVA film in water and washing it with water before dyeing, you can not only wash dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film and prevent uneven dyeing. It can be prevented.

Specific examples of polarizers obtained using a laminate include a laminate of a resin base material and a PVA resin layer (PVA resin film) laminated on the resin base material, or a laminate of a resin base material and the resin Examples include polarizers obtained using a laminate with a PVA-based resin layer coated on a base material. A polarizer obtained using a laminate of a resin base material and a PVA-based resin layer coated on the resin base material can be obtained by, for example, applying a PVA-based resin solution to the resin base material and drying it. Forming a PVA-based resin layer thereon to obtain a laminate of a resin base material and the PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In this embodiment, preferably, a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin is formed on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, the stretching may further include stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the boric acid aqueous solution, if necessary. In addition, in the present embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process in this order. By introducing auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it becomes possible to improve the crystallinity of PVA and achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when it is immersed in water during the subsequent dyeing and stretching processes, resulting in high optical properties. becomes possible to achieve. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance in the orientation of polyvinyl alcohol molecules and deterioration of orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. Thereby, the optical properties of a polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Furthermore, optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin base material/polarizer laminate may be used as is (that is, the resin base material may be used as a protective layer for the polarizer), or the resin base material may be peeled from the resin base material/polarizer laminate. Any appropriate protective layer may be laminated on the peeled surface or on the surface opposite to the peeled surface depending on the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

The thickness of the polarizer is preferably 10 μm or less, more preferably 1 μm to 8 μm, and still more preferably 3 μm to 7 μm. In an optical laminate having such a very thin polarizer, the effects of the embodiments of the present invention are remarkable. More details are as follows. Such very thin polarizers generally have a high iodine concentration, and it is presumed that frame-like display defects may occur due to anisotropic reflection caused by the interaction between iodine and the above-mentioned light-absorbing compound. According to an embodiment of the present invention, by controlling the single transmittance of the polarizer or the moisture permeability of the protective layer on the pressure-sensitive adhesive layer side, such interaction can be reduced and frame-like display defects can be suppressed. Note that this mechanism is just an estimate, and the present invention and its mechanism are not restricted by this estimate. In addition, if the thickness of the polarizer is within the above range, curling during heating can be suppressed well, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at a wavelength of 380 nm to 780 nm. As mentioned above, the single transmittance of the polarizer is 43.3% or more, preferably 43.3% to 46.0%, more preferably 43.3% to 45.0%. If the single transmittance of the polarizer is within such a range, the iodine concentration can be controlled within a desired range, and as a result, frame-like display defects can be suppressed. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more. According to the embodiment of the present invention, even if the single transmittance is within the above range, the degree of polarization can be maintained within this range.

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. If 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 the interaction can be reduced. As a result, frame-like display defects can be suppressed in an optical laminate having a very thin polarizer. Note that in this specification, "iodine concentration" means the total amount of iodine contained in the polarizer. More specifically, iodine exists in the form of ^I- , _I2 , _I3- ^, etc. in the polarizer, and the iodine concentration in this specification means the concentration of iodine including all of these forms. . The iodine concentration can be calculated, for example, from the fluorescent X-ray intensity determined by fluorescent X-ray analysis and the film (polarizer) thickness.

D-2. Protective layer The protective layer 32 has a moisture permeability of 100 g/cm ^2.24 hr or less, preferably 70 g/cm ^2.24 hr or less, more preferably 50 g/ ^cm 2.24 hr or less, particularly preferably is 40 g/cm ² ·24 hr or less, particularly preferably 30 g/cm ² ·24 hr or less, and most preferably 25 g/cm ² ·24 hr or less. The lower limit of moisture permeability may be, for example, 5 g/cm ² ·24 hr. If the moisture permeability of the protective layer is within this range, it is possible to satisfactorily suppress the transfer of the light-absorbing compound from the adhesive layer to the polarizing plate (substantially, the polarizer). As a result, frame-like display defects can be effectively suppressed.

The protective layer 32 is made of any suitable resin film as long as it can achieve moisture permeability within the above range. Materials constituting the resin film typically include cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, etc. Examples include polyolefin resins and polycarbonate resins. A typical example of the (meth)acrylic resin is a (meth)acrylic resin having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are disclosed in, for example, JP-A Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005. It is described in the publication No.-146084. These publications are incorporated herein by reference. The protective layer 32 is preferably made of cycloolefin resin or (meth)acrylic resin.

The optical laminate is typically placed on the viewing side of the image display device, and the protective layer 32 is typically placed on the viewing side. Therefore, the protective layer 32 may be subjected to surface treatment if necessary. Examples of the surface treatment include hard coat treatment, antireflection treatment, antisticking treatment, and antiglare treatment. In the embodiment of the present invention, hard coat treatment (formation of a hard coat layer) is preferred. The hard coat layer will be described later. A combination of hard coat treatment and other surface treatments may be applied. Additionally/or, the protective layer 32 may be treated as necessary to improve visibility when viewed through polarized sunglasses (typically, imparting (elliptical) circular polarization function, ultra-high retardation ) may be applied. By performing such processing, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the optical laminate can also be suitably applied to image display devices that can be used outdoors.

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. In addition, when surface treatment is performed, the thickness of the protective layer is the thickness including the thickness of the surface treatment layer.

Another protective layer (if present) is formed of any suitable film that can be used as a protective layer for a polarizer. Materials constituting another protective layer typically include cellulose resins such as triacetyl cellulose (TAC), cycloolefin resins, (meth)acrylic resins, polyester resins, polyolefin resins, and polycarbonate resins. Examples include resin. The thickness of another protective layer can be appropriately set depending on the purpose.

The further protective layer is preferably optically isotropic in one embodiment. In this specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. say.

D-3. Hard Coat Layer In one embodiment, the hard coat layer 33 may be formed on the adhesive layer 20 side of the protective layer 32 of the polarizing plate 30 as described above. By providing a hard coat layer, a synergistic effect with the moisture permeability control effect of the protective layer on the adhesive layer side allows the transition of light-absorbing compounds from the adhesive layer to the polarizing plate (substantially, a polarizer). can be suppressed even better. As a result, frame-like display defects can be suppressed even better. The hard coat layer 33 is typically a cured layer of any suitable active energy ray (eg, ultraviolet ray, visible light, electron beam) curable resin. Examples of active energy ray-curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain any appropriate additives as necessary. Representative examples of the additive 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.

E. Retardation Layer As described above, the retardation layer 40 typically has a circular polarization function or an elliptical polarization function. Furthermore, as described above, the retardation layer 40 may be composed of a stretched resin film or may be a liquid crystal alignment solidified layer. Hereinafter, each of the stretched resin film and the liquid crystal alignment solidified layer will be explained.

E-1. Stretched resin film E-1-1. Characteristics If the retardation layer has such a configuration, by controlling the single transmittance of the polarizer or the moisture permeability of the protective layer on the adhesive layer side, it is possible to form a frame shape in an optical laminate having an adhesive layer containing a light-absorbing compound. Display defects can be suppressed. In this 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 Re(450)<Re(550). Further, the angle between 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°, and even more preferably 44° to 48°. 46°, particularly preferably about 45°.

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

The retardation layer typically satisfies the relationship Re(450)<Re(550) as described above, and preferably further satisfies the relationship Re(550)<Re(650). That is, the retardation layer exhibits wavelength dependence of inverse dispersion in which the retardation value increases depending on 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, 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.

Since the retardation layer has an in-plane retardation as described above, it has a relationship of nx>ny. The retardation layer exhibits any appropriate refractive index characteristics as long as it has the relationship nx>ny. The refractive index characteristic of the retardation layer typically shows the relationship nx>ny≧nz. Note that "ny=nz" here includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, there may be a case where ny<nz within a range that does not impair the effects of the present invention. 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, an extremely excellent reflected hue can be achieved.

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 to obtain a desired in-plane retardation. 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.

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

The retardation layer typically further contains an acrylic resin. The content of acrylic resin is 0.5% by mass to 1.5% by mass. In addition, in this specification, the percentage or part of the unit of "mass" is synonymous with the percentage or part of the unit of "weight."

E-1-2-1. Polycarbonate resin 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 to R ³ are each independently a direct bond, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R ⁴ to R ⁹ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, and a substituted or unsubstituted aryl group having 1 to 10 carbon atoms; Substituted alkoxy group having 1 to 10 carbon atoms, substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, substituted or unsubstituted amino group, substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, substituted or An unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group. However, R ⁴ to R ⁹ may be the same or different, and at least two adjacent groups among R ⁴ to R ⁹ may be bonded to each other to form a ring.

The content of oligofluorene structural units in the polycarbonate resin etc. is preferably 1% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, and even more preferably 15% by mass, based on the entire resin. % to 30% by weight, particularly preferably 18% to 25% by weight. When the content of oligofluorene structural units is too large, problems such as an excessively large photoelastic coefficient, insufficient reliability, and insufficient retardation development may occur. Furthermore, since the proportion of oligofluorene structural units in the resin increases, the range of molecular design becomes narrower, which may make it difficult to modify the resin when it is required. On the other hand, even if the desired inverse dispersion wavelength dependence could be obtained with a very small amount of oligofluorene structural units, in this case the optical properties would be sensitive to slight variations in the content of oligofluorene structural units. Therefore, it may be difficult to manufacture products so that the various properties fall within a certain range.

Details of the oligofluorene structural unit are described in, for example, International Publication No. 2015/159928 pamphlet. This publication is incorporated herein by reference.

<Other structural units>
Polycarbonate resins and the like may typically contain other structural units in addition to oligofluorene structural units. In one embodiment, the other structural units may preferably be derived from dihydroxy or diester compounds. In order to achieve the desired reverse wavelength dispersion, it is necessary to incorporate into the polymer structure a structural unit with positive intrinsic birefringence along with an oligofluorene structural unit with negative intrinsic birefringence. The monomer is more preferably a dihydroxy compound or a diester compound that serves as a raw material for a structural unit having positive birefringence.

Examples of copolymerizable monomers include compounds into which a structural unit containing an aromatic ring can be introduced, and compounds which do not introduce a structural unit containing an aromatic ring, that is, compounds having an aliphatic structure.
Specific examples of the compounds constituted by the aliphatic structure are listed below. Ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexane dihydroxy compounds of linear aliphatic hydrocarbons such as diol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol; dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol, hexylene glycol, etc. Compounds; exemplified by 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc. , secondary alcohols of alicyclic hydrocarbons, and dihydroxy compounds that are tertiary alcohols; 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, Pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3- Dihydroxy compounds that are primary alcohols of alicyclic hydrocarbons, such as dihydroxy compounds derived from terpene compounds such as adamantane dimethanol and limonene; diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene Oxyalkylene glycols such as glycol; dihydroxy compounds having a cyclic ether structure such as isosorbide; dihydroxy compounds having a cyclic acetal structure such as spiroglycol and dioxane glycol; 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, Alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; 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 structural unit containing the aromatic ring 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(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-hydroxy phenyl) sulfide, bis(4-hydroxy-3-methylphenyl) sulfide, bis(4-hydroxyphenyl) disulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether, etc. Aromatic bisphenol compounds; 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxy) Dihydroxy compounds having an ether group bonded to an aromatic group such as ethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, bis(4-(2-hydroxyethoxy)phenyl)sulfone; terephthalic acid, phthalate Acid, isophthalic acid, 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, 4,4'-diphenyl sulfone Aromatic dicarboxylic acids such as dicarboxylic acid and 2,6-naphthalene dicarboxylic acid.
The aliphatic dicarboxylic acid and aromatic dicarboxylic acid components mentioned above can be used as dicarboxylic acids themselves as raw materials for the polyester carbonate, but depending on the manufacturing method, dicarboxylic acids such as methyl esters and phenyl esters may be used. Esters and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

As copolymerization monomers, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and 9,9-bis(4- Dihydroxy compounds having a fluorene ring, such as hydroxyphenyl)fluorene and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and dicarboxylic acid compounds having a fluorene ring can also be used in combination with the oligofluorene compound.

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

Spiroglycol can be used as the dihydroxy compound into which the structural unit of formula (3) can be introduced.

In the resin used in the present invention, the structural unit represented by the formula (3) is preferably 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, 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, particularly preferably 25% by mass or more. If the content of the structural unit represented by the formula (3) is equal to or higher than the lower limit, sufficient mechanical properties, heat resistance, and low photoelastic coefficient can be obtained. Furthermore, the compatibility with the acrylic resin is improved, and the transparency of the resulting resin composition can be further improved. Furthermore, since the speed of the polymerization reaction of spiroglycol is relatively slow, the polymerization reaction can be easily controlled by suppressing the content below the above-mentioned upper limit.

It is preferable that the resin used in the present invention further contains a structural unit represented by the following formula (4) as a copolymerization component.

Examples of the dihydroxy compound into which the structural unit represented by the formula (4) can be introduced include isosorbide (ISB), isomannide, and isoidet, which are stereoisomers. These may be used alone or in combination of two or more.

In the resin used in the present invention, the structural unit represented by formula (4) is preferably 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, particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, particularly preferably 15% by mass or more. If the content of the structural unit represented by the formula (4) is equal to or higher than the lower limit, sufficient mechanical properties, heat resistance, and low photoelastic coefficient can be obtained. Furthermore, since the structural unit represented by the above formula (4) has a property of high water absorption, if the content of the structural unit represented by the above formula (4) is below the above upper limit, the molded product will not absorb water due to water absorption. Dimensional changes can be suppressed within an acceptable range.

The resin used in the present invention may further contain another structural unit. Note that such structural units may be referred to as "other structural units." As monomers having other structural units, it is more preferable to employ 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, 1,4-cyclohexanedicarboxylic acid (and derivatives thereof), and 1,4-cyclohexanedicarboxylic acid (and its derivatives). Particularly preferred are methanol and tricyclodecane dimethanol. Resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, etc. Moreover, since the polymerization reactivity of diester compounds is relatively low, from the viewpoint of increasing reaction efficiency, it is preferable not to use diester compounds other than diester compounds containing oligofluorene structural units.

The glass transition temperature (Tg) of the resin used in the present invention is preferably 110°C or more and 160°C or less. The upper limit is more preferably 155°C or lower, more preferably 150°C or lower, particularly preferably 145°C or lower. The lower limit is more preferably 120°C or higher, particularly preferably 130°C or higher. If the glass transition temperature is outside the above range, the heat resistance tends to deteriorate, and there is a possibility that dimensional changes may occur after the film is formed, and the reliability of quality under the usage conditions of the retardation film may deteriorate. On the other hand, if the glass transition temperature is too high, uneven film thickness may occur during film forming, the film may become brittle, and stretchability may deteriorate, and the transparency of the film may be impaired.

Details of the structure and manufacturing method of the polycarbonate resin etc. are described in, for example, International Publication No. 2015/159928 pamphlet (above). This description is incorporated herein by reference.

E-1-2-2. Acrylic Resin As the acrylic resin, an acrylic resin as a thermoplastic resin is used. Examples of monomers that serve as 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, hydroxy Propyl (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, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acrylic succinate yloxyethyl, 2-(meth)acryoyloxyethyl maleate, 2-(meth)acryoyloxyethyl phthalate, 2-(meth)acryoyloxyethyl 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 alone or in combination of two or more. Examples of forms in which two or more types of monomers are used in combination include copolymerization of two or more types of monomers, blends of two or more homopolymers of one type of monomer, and combinations thereof. Furthermore, other monomers copolymerizable with these acrylic monomers (for example, olefin monomers, vinyl monomers) may be used in combination.

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, further preferably 90% by mass or more, 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, so by adjusting the refractive index of the resin to be combined, the resulting resin composition can be made transparent. can improve sex. By using such an acrylic resin, it is possible to obtain a reverse dispersion retardation film that is excellent in stretchability and retardation development and has low haze.

The weight average molecular weight Mw of the acrylic resin is 10,000 or more and 200,000 or less. The lower limit is preferably 30,000 or more, particularly preferably 50,000 or more. The upper limit is preferably 180,000 or less, particularly preferably 150,000 or less. If the molecular weight is in this range, it is possible to improve the transparency of the final retardation film (retardation layer) by obtaining compatibility with the polycarbonate resin, and it is possible to improve the transparency during stretching. The effect of sufficiently improving sex can be obtained. In addition, the above-mentioned weight average molecular weight is a polystyrene equivalent molecular weight measured by GPC. Further, from the viewpoint of compatibility, it is preferable that the acrylic resin does not substantially contain a branched structure. The fact that the acrylic resin does not contain a branched structure can be confirmed by the fact that the GPC curve of the acrylic resin is unimodal.

E-1-2-3. Blend of polycarbonate resin etc. and acrylic resin Polycarbonate resin etc. and acrylic resin are blended and used as a resin composition in a method for producing a retardation film (retardation layer). The content of the acrylic resin in the resin composition (as a result, the retardation 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 weight or less, more preferably 1.0% by weight or less, further preferably 0.9% by weight or less, particularly preferably 0.8% by weight or less. In this way, by blending the acrylic resin with the polycarbonate resin in a very limited ratio, the extensibility and retardation development property can be significantly increased. Furthermore, haze can be suppressed. Such an effect is not theoretically obvious, but is an unexpectedly excellent effect obtained through trial and error. Note that if the content of the acrylic resin is too small, the above effects may not be obtained. On the other hand, if the content of the acrylic resin is too high, the haze may become high. In addition, the extensibility and retardation properties are often insufficient or even lower than those within the above ranges.

The resin composition is made of aromatic polycarbonate, aliphatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, acrylic, amorphous polyolefin, etc. for the purpose of modifying properties such as mechanical properties and/or solvent resistance. Synthetic resins such as ABS, AS, polylactic acid, polybutylene succinate, rubber, and combinations thereof may be further blended.

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, lubricants, and plasticizers. agent, compatibilizer, nucleating agent, flame retardant, inorganic filler, and blowing agent. The type, number, combination, content, etc. of additives contained in the resin composition can be appropriately set depending on the purpose.

E-1-3. Method for Forming Retardation Layer The retardation layer is obtained by forming a film from the resin composition and then stretching the film. As the method for forming the retardation layer (method for stretching the resin film), conditions well known in the industry may be employed, and detailed description thereof will be omitted.

E-2. Liquid crystal alignment solidified layer If the retardation layer has such a configuration, the optical laminate can be made significantly thinner. In this case, as described above, the retardation layer may be a single layer or may have a two-layer structure of the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer. As used herein, the term "orientation-fixed layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction and the orientation state is fixed. Note that the term "alignment hardened layer" is a concept that includes an orientation hardened layer obtained by curing a liquid crystal monomer. In the retardation layer, rod-shaped liquid crystal compounds are typically aligned in the slow axis direction of the retardation layer (homogeneous alignment).

Examples of liquid crystal compounds include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable. If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it. Here, the polymer formed by polymerization is non-liquid crystalline. Therefore, the formed retardation layer does not undergo transition to a liquid crystal phase, a glass phase, or a crystalline phase due to a temperature change, which is characteristic of liquid crystal compounds, for example. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

In one embodiment, the retardation layer may be formed using a composition containing a polymerizable liquid crystal compound (polymerizable liquid crystal compound). In this specification, the polymerizable liquid crystal compound contained in the composition refers to a compound that has a polymerizable group and has liquid crystallinity. A polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by active radicals, acids, etc. generated from a photopolymerization initiator.

The mechanism for developing liquid crystallinity of the liquid crystal compound may be thermotropic or lyotropic. Furthermore, the structure of the liquid crystal phase may be nematic liquid crystal or smectic liquid crystal. From the viewpoint of ease of manufacture, thermotropic nematic liquid crystal is preferred.

The temperature range in which a liquid crystal monomer exhibits liquid crystallinity differs depending on its 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.

E-2-1. Single layer When the liquid crystal alignment solidified layer is a single layer, the characteristics except for the thickness are as explained in Section E-1-1 regarding the stretched film of the resin film. When the liquid crystal alignment solidified layer is a single layer, the thickness may be, for example, 1.0 μm to 5.0 μm, or, for example, 1.0 μm to 3.0 μm.

The retardation 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)

L ¹ and L ² each independently represent a monovalent organic group, and at least one of L ¹ and L ² represents a polymerizable group. The monovalent organic group includes any suitable group. The polymerizable group represented by at least one of L ¹ and L ² includes a radically polymerizable group (radically polymerizable group). Any suitable radically polymerizable group can be used as the radically polymerizable group. Preferably it is an acryloyl group or a methacryloyl group. An acryloyl group is preferred from the viewpoint of high polymerization rate and improved productivity. A methacryloyl group can similarly be used as a polymerizable group for highly birefringent liquid crystals.

SP ¹ and SP ² each independently constitute a single bond, a linear or branched alkylene group, or a linear or branched alkylene group having 1 to 14 carbon atoms -CH ₂ One or more of - represents a divalent linking group substituted with -O-. Preferable examples of the linear or branched alkylene group having 1 to 14 carbon atoms include methylene group, ethylene group, propylene group, butylene group, pentylene group and hexylene group.

A ¹ and A ² each independently represent an alicyclic hydrocarbon group or an aromatic ring substituent. A ¹ and A ² are preferably aromatic ring substituents having 6 or more carbon atoms or cycloalkylene rings having 6 or more carbon atoms.

D ¹ , D ² , D ³ and D ⁴ each independently represent a single bond or a divalent linking group. Specifically, D ¹ , D ² , D ³ and D ⁴ are single bonds, -O-CO-, -C(=S)O-, -CR 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. However, at least one of D ¹ , D ² , D ³ and D ⁴ represents -O-CO-. Among these, it is preferable that D ³ is -O-CO-, and it is more preferable that D ³ and D ⁴ are -O-CO-. D ¹ and D ² are preferably single bonds. R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms.

G ¹ and G ² each independently represent a single bond or an alicyclic hydrocarbon group. Specifically, G ¹ and G ² may represent an unsubstituted or substituted divalent alicyclic hydrocarbon group having 5 to 8 carbon atoms. Furthermore, one or more of -CH ₂ - constituting the alicyclic hydrocarbon group may be substituted with -O-, -S- or -NH-. G ¹ and G ² preferably represent a single bond.

Ar represents an aromatic hydrocarbon ring or an aromatic heterocycle. Ar represents, for example, 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 represents the bonding position with D ¹ and *2 represents the bonding position with D ² .

In formula (Ar-1), Q ¹ represents N or CH, and Q ² represents -S-, -O-, or -N(R ⁵ )-. R ⁵ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y ¹ 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.

In formulas (Ar-1) to (Ar-6), Z ¹ , Z ² and Z ³ each independently represent a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, or a C 3 Represents a monovalent alicyclic hydrocarbon group having ~20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitro group, -NR ⁶ R ⁷ , or -SR ⁸ . R ⁶ to R ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z ¹ and Z ² may be bonded to each other to form a ring. The ring may be an alicyclic ring, a heterocyclic ring, or an aromatic ring, and is preferably an aromatic ring. The formed ring may be substituted with a substituent.

In formulas (Ar-2) and (Ar-3), A ³ and A ⁴ are each independently a group consisting of -O-, -N(R ⁹ )-, -S-, and -CO- R ⁹ represents a hydrogen atom or a substituent. Examples of the substituent represented by R ⁹ include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In formula (Ar-2), X represents a hydrogen atom or a non-metal atom of Groups 14 to 16 which is unsubstituted or has a substituent. Examples of the Group 14 to Group 16 nonmetal atom represented by X include an oxygen atom, a sulfur atom, a nitrogen atom that is unsubstituted or has a substituent, and a carbon atom that is unsubstituted or has a substituent. Examples of the substituent include the same substituents that Y ¹ in the above formula (Ar-1) may have.

In formula (Ar-3), D ⁵ and D ⁶ each independently represent a single bond, -O-CO-, -C(=S)O-, -CR 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 R ⁴ are as described above.

In formula (Ar-3), SP ³ and SP ⁴ are each independently a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms, or a straight chain having 1 to 12 carbon atoms. A divalent compound in which one or more of -CH ₂ - constituting a shaped or branched alkylene group is substituted with -O-, -S-, -NH-, -N(Q)-, or -CO- represents a connecting group, and Q represents a polymerizable group.

In formula (Ar-3), L ³ and L ⁴ each independently represent a monovalent organic group, and at least one of L ³ and L ⁴ and L ¹ and L ² in the above formula (1) is Represents a polymerizable group.

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

In formulas (Ar-4) to (Ar-6), Q ³ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may be unsubstituted or have a substituent. In formulas (Ar-4) to (Ar-6), Q ³ preferably represents a hydrogen atom.

Among such Ar, preferable examples include groups (atomic groups) represented by the above formula (Ar-4) or the above formula (Ar-6).

The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination. Specific examples of liquid crystal compounds are described in, for example, JP-A No. 2006-163343, JP-A No. 2006-178389, and International Publication No. 2018/123551. The descriptions of these publications are incorporated herein by reference.

E-2-2. Two-layer structure of a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer When the retardation layer has a two-layer structure of a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer from the polarizing plate side, the first The liquid crystal alignment fixed layer can typically function as a λ/2 plate, and the second liquid crystal alignment fixed layer can typically function as a λ/4 plate. Specifically, Re (550) of the first liquid crystal alignment and solidification layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and still more preferably 250 nm to 280 nm; Re(550) is as explained in Section E-1-1 regarding the stretched resin film. The thickness of the first liquid crystal alignment solidified layer can be adjusted so as to obtain a desired in-plane retardation of the λ/2 plate. Specifically, the thickness may be, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment solidified layer can be adjusted so as to obtain a desired in-plane retardation of the λ/4 plate. Specifically, the 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 solidified layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and Preferably it is 14° to 16°; the angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°. and more preferably 74° to 76°. Note that the arrangement order of the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer may be reversed, and the angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer and the second liquid crystal The angle between the slow axis of the alignment solidified layer and the absorption axis of the polarizer may be reversed. The first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer may exhibit inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light, and the retardation value decreases according to the wavelength of the measurement light. It may exhibit a positive wavelength dispersion characteristic, or it may exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light.

The retardation layer of this embodiment is formed using, for example, a composition containing any suitable liquid crystal monomer. Examples of liquid crystal monomers include Japanese Patent Application Publication No. 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB22. The polymerizable mesogenic compounds described in 80445 etc. Can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's product name LC242, Merck's product name E7, and Wacker-Chem's product name LC-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

F. Another Retardation Layer The other retardation layer 50 may be a so-called positive C plate whose refractive index characteristics exhibit the relationship nz>nx=ny, as described above. By using a positive C plate as another retardation layer, reflection in an oblique direction can be effectively prevented, and the antireflection function can provide a wide viewing angle. In this case, the retardation Rth (550) in the thickness direction of another retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm. The wavelength is particularly preferably -100 nm to -180 nm. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. That is, the in-plane retardation Re(550) of another retardation layer may be less than 10 nm.

Another retardation layer may be formed of any suitable material. The further retardation layer preferably consists of a film containing liquid crystal material fixed in a homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of JP-A No. 2002-333642. In this case, the thickness of the other retardation 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.

G. Image Display Device The optical laminate described in items A to F above can be applied to an image display device. 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. The image display device according to the embodiment of the present invention typically includes the optical laminate described in Sections A to F above on its viewing side. The optical laminate is arranged with the front plate facing the viewing side.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

・ＩＳＢ：イソソルビド［ロケットフルーレ社製］
・ＳＰＧ：スピログリコール［三菱ガス化学（株）製］
・ＤＰＣ：ジフェニルカーボネート［三菱ケミカル（株）製］ [Compound abbreviation]
The abbreviations of compounds used in the following production examples are as follows.
- BPFM: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane Synthesized by the method described in JP-A-2015-25111.

・ISB: Isosorbide [manufactured by Roquette Fleuret]
・SPG: Spiroglycol [manufactured by Mitsubishi Gas Chemical Co., Ltd.]
・DPC: Diphenyl carbonate [manufactured by Mitsubishi Chemical Corporation]

[Production Example 1: Production of retardation film constituting the retardation layer]
Polymerization was carried out using a batch polymerization apparatus consisting of two vertical stirring reactors equipped with a stirring blade and a reflux condenser. 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 ⁻⁴ parts by mass (4.47×10 ⁻⁶ mol) of calcium acetate monohydrate as a catalyst were charged. After the inside of the reactor was replaced with nitrogen under reduced pressure, it was heated with a heating medium, and when the internal temperature reached 100°C, stirring was started. 40 minutes after the start of temperature rise, the internal temperature was controlled to reach 220°C, and at the same time, pressure reduction was started to maintain this temperature, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 220°C. Phenol vapor produced as a by-product during the polymerization reaction was led to a 110°C reflux condenser, a small amount of monomer component contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was led to a 45°C condenser for recovery. After nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 240° C. and the pressure was 20 kPa in 40 minutes. Thereafter, while lowering the pressure further, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, the produced polyester carbonate was extruded into water, and the strands were 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% by mass. The reduced viscosity of PC1 is 0.46 dL/g, Mw is 48,000, refractive index _nD is 1.526, melt viscosity is 2480 Pa·s, glass transition temperature is 139°C, and photoelastic coefficient is 9×10 ⁻¹² [ m ² /N], and the wavelength dispersion Re(450)/Re(550) was 0.85.

Using Dianal BR80 (manufactured by Mitsubishi Chemical Corporation) as the acrylic resin, extrusion kneading with the obtained polyester carbonate was performed. A mixture of polycarbonate pellets (99.5 parts by mass) and BR80 powder (0.5 parts by mass) was charged into a twin-screw extruder TEX30HSS manufactured by Japan Steel Works, Ltd. using a quantitative feeder. The extruder cylinder temperature was set at 250° C., and extrusion was performed at a throughput of 12 kg/hr and a screw rotation speed of 120 rpm. Further, the extruder was equipped with a vacuum vent, and the molten resin was extruded while being devolatilized under reduced pressure. After vacuum drying the pellets of the resin composition obtained in this way at 100°C for 6 hours or more, a single screw extruder (manufactured by Isuzu Kakoki Co., Ltd., screw diameter 25 mm, cylinder temperature setting: 250°C), A long film with a length of 3 m, width of 200 mm, and thickness of 100 μm is produced using a film forming apparatus equipped with a T-die (width: 300 mm, set temperature: 220 °C), chill roll (set temperature: 120 to 130 °C), and winder. An unstretched film was produced. This long unstretched film was stretched at a stretching temperature of Tg and a stretching ratio of 2.7 times to obtain a retardation film R1 having a thickness of 37 μm. Re (550) of the obtained retardation film R1 was 141 nm, Re (450)/Re (550) was 0.82, and Nz coefficient was 1.12.

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

ポリエチレンテレフタレート（ＰＥＴ）フィルム（厚み３８μｍ）表面を、ラビング布を用いてラビングし、配向処理を施した。配向処理の方向は、偏光板に貼り合わせる際に偏光膜の吸収軸の方向に対して視認側から見て１５°方向となるようにした。この配向処理表面に、上記液晶塗工液をバーコーターにより塗工し、９０℃で２分間加熱乾燥することによって液晶化合物を配向させた。このようにして形成された液晶層に、メタルハライドランプを用いて１ｍＪ/ｃｍ２の光を照射し、当該液晶層を硬化させることによって、ＰＥＴフィルム上に液晶配向固化層Ａを形成した。液晶配向固化層Ａの厚みは２．５μｍ、面内位相差Ｒｅ（５５０）は２７０ｎｍであった。さらに、液晶配向固化層Ａは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。
塗工厚みを変更したこと、および、配向処理方向を偏光膜の吸収軸の方向に対して視認側から見て７５°方向となるようにしたこと以外は上記と同様にして、ＰＥＴフィルム上に液晶配向固化層Ｂを形成した。液晶配向固化層Ｂの厚みは１．５μｍ、面内位相差Ｒｅ（５５０）は１４０ｎｍであった。さらに、液晶配向固化層Ｂは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。
液晶配向固化層Ａおよび液晶配向固化層Ｂは、光学積層体においてこの順に偏光板に転写される。 [Production Example 3: Production of the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer constituting the retardation layer]
10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, product name "Paliocolor LC242", represented by the following formula) and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, product name "Irgacure 907") ) was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed using a rubbing cloth to perform orientation treatment. The direction of the alignment treatment was set to be 15° when viewed from the viewing side with respect to the direction of the absorption axis of the polarizing film when bonding to the polarizing plate. The above-mentioned liquid crystal coating solution was applied to this alignment-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90° C. for 2 minutes. The thus formed liquid crystal layer was irradiated with light of 1 mJ/cm 2 using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal alignment solidified layer A on the PET film. The thickness of the liquid crystal alignment solidified layer A was 2.5 μm, and the in-plane retardation Re (550) was 270 nm. Furthermore, the liquid crystal alignment solidified layer A had a refractive index distribution of nx>ny=nz.
The coating was applied on the PET film in the same manner as above, except that the coating thickness was changed and the orientation treatment direction was set at 75° when viewed from the viewing side with respect to the direction of the absorption axis of the polarizing film. A liquid crystal alignment solidified layer B was formed. The thickness of the liquid crystal alignment solidified layer B was 1.5 μm, and the in-plane retardation Re (550) was 140 nm. Furthermore, the liquid crystal alignment solidified layer B had a refractive index distribution of nx>ny=nz.
The liquid crystal alignment solidified layer A and the liquid crystal alignment solidified layer B are transferred to the polarizing plate in this order in the optical laminate.

[Production Example 4: Production of liquid crystal alignment solidified layer constituting another retardation layer]
20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (I) (numbers 65 and 35 in the formula indicate mol% of monomer units, and are conveniently expressed as a block polymer: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name Paliocolor LC242) and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name Irgacure 907) were dissolved in 200 parts by weight of cyclopentanone. A liquid crystal coating solution was prepared. Then, the coating solution was applied to a PET substrate subjected to vertical alignment treatment using a bar coater, and then heated and dried at 80° C. for 4 minutes to align the liquid crystal. By irradiating this liquid crystal layer with ultraviolet rays and curing the liquid crystal layer, another retardation layer (thickness: 3 μm) having a refractive index characteristic of nz>nx=ny was formed on the base material. Another retardation layer is transferred to the retardation layer in the optical stack.

[Manufacture example 5: Preparation of polarizing plate]
(Preparation of polarizer)
As the thermoplastic resin base material, a long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of approximately 75° C. was used, and one side of the resin base material was subjected to corona treatment.
100 parts by weight of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name "Gosefaimer") at a ratio of 9:1. to which 13 parts by weight of potassium iodide was added was dissolved in water to prepare a PVA aqueous solution (coating solution).
The PVA aqueous solution was applied to the corona-treated surface of the resin base material and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.
The obtained laminate was uniaxially stretched 2.4 times in the vertical direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed for 30 seconds in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40° C. (insolubilization treatment).
Next, the final polarizer was added to a dyeing bath (an aqueous iodine solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C. The sample was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) became a desired value (staining treatment).
Next, it was immersed for 30 seconds in a crosslinking bath (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C. (Crosslinking treatment).
Thereafter, while immersing the laminate 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, the laminate was completely rolled in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven kept at about 90°C, it was brought into contact with a SUS heating roll whose surface temperature was kept at about 75°C (drying shrinkage treatment).
In this way, a polarizer having a thickness of about 5 μm was formed on the resin base material, and a polarizing plate having a resin base material/polarizer configuration was obtained. The single transmittance Ts of the polarizer was 43.3%.

(Preparation of polarizing plate)
An HC-TAC film was attached to the surface of the obtained polarizer (the surface opposite to the resin base material) via an ultraviolet curable adhesive. Note that the HC-TAC film is a film in which an HC layer (7 μm thick) is formed on a triacetyl cellulose (TAC) film (25 μm thick), and the TAC film is attached to the polarizer side. Next, the resin base material was peeled off to obtain a polarizing plate P1 having a structure of HC layer/TAC film (protective layer)/polarizer. The moisture permeability of the protective layer was 400 g/m ² ·24 hr.

[Production Example 6: Production of polarizing plate]
The HC layer/COP film (protective A polarizing plate P2 having a structure of layer)/polarizer was obtained. Note that 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 the COP film is attached to the polarizer side. The moisture permeability of the protective layer was 20 g/m ² ·24 hr.

[Production Example 7: Production of polarizing plate]
A polarizing plate P3 having a configuration of HC layer/COP film (protective layer)/polarizer was obtained in the same manner as Production Example 6 except that the single transmittance Ts of the polarizer was 44.0%.

[Production Example 8: Production of polarizing plate]
A polarizing plate P4 having a configuration of HC layer/TAC film (protective layer)/polarizer was obtained in the same manner as Production Example 5 except that the single transmittance Ts of the polarizer was 42.0%.

[Production Example 9: Production of polarizing plate]
The HC layer/acrylic film was prepared in the same manner as in Production Example 5 except that the single transmittance Ts of the polarizer was 42.5% and that an acrylic film (thickness 40 μm) was used instead of the HC-TAC film. A polarizing plate P5 having a structure of (protective layer)/polarizer was obtained. The moisture permeability of the protective layer was 70 g/m ² ·24 hr.

[Production Example 10: Production of polarizing plate]
(Preparation of polarizer)
A long roll of polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") with a thickness of 30 μm was simultaneously uniaxially stretched in the longitudinal direction to a length of 5.9 times using a roll stretching machine. A polarizer with a thickness of 12 μm was produced by performing swelling, dyeing, crosslinking, washing, and finally drying. The single transmittance Ts of the polarizer was 43.5%.
Specifically, in the swelling treatment, the film was stretched 2.2 times while being treated with pure water at 20°C. Next, the dyeing treatment was carried out in an aqueous solution at 30 °C in which the weight ratio of iodine and potassium iodide was 1:7, and the iodine concentration was adjusted so that the single transmittance of the obtained polarizer was 43.5%. However, it was stretched 1.4 times. Furthermore, a two-stage crosslinking process was adopted for the crosslinking process, and the first crosslinking process was performed in an aqueous solution containing boric acid and potassium iodide at 40°C, and was stretched to 1.2 times. The boric acid content of the aqueous solution for the first stage crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. In the second stage of crosslinking treatment, the film was stretched to 1.6 times while being treated in an aqueous solution containing boric acid and potassium iodide at 65°C. The boric acid content of the aqueous solution for the second stage crosslinking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight. Further, the cleaning treatment was performed using a potassium iodide aqueous solution at 20°C. The potassium iodide content of the aqueous solution for cleaning treatment was 2.6% by weight. Finally, the drying process was performed at 70° C. for 5 minutes to obtain a polarizer.

(Preparation of polarizing plate)
An HC-TAC film is attached to one side of the above polarizer via a polyvinyl alcohol adhesive, and a TAC film (thickness 25 μm) is attached to the other side via a polyvinyl alcohol adhesive. A polarizing plate P6 having a structure of (protective layer)/polarizer/TAC film (protective layer) was obtained.

[Production 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, to 100 parts of the monomer mixture (solid content), 0.5 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator was charged together with 250 parts by weight of ethyl acetate. The mixture was stirred for 1 hour under a nitrogen atmosphere and replaced with nitrogen. Thereafter, the mixture was reacted at 56° C. for 5 hours, and then at 70° C. for 3 hours to prepare an acrylic base polymer solution. To the solution of the acrylic base polymer obtained above, the following post-addition components were added to 100 parts of the base polymer and mixed uniformly to prepare a photocurable adhesive.
(Post-added ingredients)
Dipentaerythritol hexaacrylate as a polyfunctional compound (photo curing agent): 2 parts Polypropylene glycol diacrylate (trade name: APG400, manufactured by Shin Nakamura Chemical Industry Co., Ltd., polypropylene glycol #400 ( n=7) diacrylate, functional group equivalent 268 g/eq): 3 parts Photopolymerization initiator (4-methylbenzophenone, maximum absorption wavelength 280 nm): 0.2 part (preparation of adhesive sheet)
A photocurable adhesive was applied to a release liner (75 μm thick polyethylene terephthalate (PET) film with a silicone release layer on the surface: “Diafoil MRF75” manufactured by Mitsubishi Chemical Corporation) and heated at 100°C for 3 minutes. After removing the solvent, the same release liner as above was attached to the surface. The thus obtained 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.

[Example 1]
The retardation film R1 obtained in Production Example 1 was bonded to the polarizer surface of the polarizing plate P1 obtained in Production Example 5 via an acrylic adhesive (thickness: 5 μm). Here, the polarizing plate P1 and the retardation layer (retardation film) R1 were bonded together so that the absorption axis of the polarizer and the slow axis of the retardation film formed an angle of 45°. Furthermore, an adhesive layer was transferred from the adhesive sheet obtained in Production Example 11 to the opposite side of the polarizing plate from the retardation film, and a front plate (glass plate with a thickness of 1.5 mm) was attached via the adhesive layer. Pasted together. Specifically, a front plate and a polarizing plate/retardation film (retardation layer) are vacuum laminated via an adhesive layer, and then ultraviolet rays are irradiated from the front plate side with an integrated light amount of 6000 mJ/cm ² to make a half-layer. The cured adhesive layer was crosslinked (cured). The thickness of the adhesive layer after curing was 150 μm. Finally, an acrylic adhesive layer (thickness: 15 μm) was provided on the opposite side of the retardation film to the polarizing plate to form another adhesive layer. A release liner was temporarily attached to the surface of the other pressure-sensitive adhesive layer. In this way, an optical laminate having the structure of front plate/adhesive layer/HC layer/protective layer/polarizer/retardation layer/another adhesive layer/release liner was obtained. The obtained optical laminate was subjected to the following evaluation of "frame-like display defects". The results are shown in Table 1.

(Frame display defect)
The obtained optical laminate was aged for 24 hours (25° C.) after the adhesive layer was cured. The aged optical laminate was subjected to a 24-hour humidification durability test at 60°C and 90% RH, and further subjected to a 72-hour humidification durability test at 60°C and 90%RH. The optical laminates after aging (initial stage), after 24 hours of testing, and after 72 hours of testing were exposed to sunlight, and the presence or absence of frame-like display defects was visually confirmed. Furthermore, the presence or absence of a frame-shaped display defect was confirmed using a multi-angle variable automatic measurement spectrophotometer (manufactured by Agilent Technologies, product name "CARY7000UMS"). When confirming frame-shaped display defects using CARY7000UMS, the incident angle of the light source was 50°, and the light receiving angle of the light receiver was 50°. In addition, a sample with a frame-like display defect was irradiated with P-polarized light and S-polarized light, and if a difference appeared in the reflection spectra of P-polarized light and S-polarized light, it was determined that there was a frame-like display defect.

[Examples 2-5, Comparative Examples 1-2]
An optical laminate was produced in the same manner as in Example 1 except that the polarizing plate and the retardation film (retardation 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.

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

The optical laminate of the present invention can be suitably used for image display devices (typically, liquid crystal display devices and organic EL display devices).

10 Front plate 20 Adhesive layer 30 Polarizing plate 31 Polarizer 32 Protective layer 33 Hard coat layer 40 Retardation layer 50 Another retardation layer 100 Optical laminate

Claims (9)

It has a front plate, an adhesive layer, a polarizing plate, and a retardation 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 having a maximum absorption wavelength of 200 nm to 300 nm,
The single transmittance of the polarizer is 43.3% or more, or the moisture permeability of the protective layer is 100 g/cm ^2.24 hr or less,
Optical laminate. The optical laminate according to claim 1, wherein the compound having a maximum absorption wavelength of 200 nm to 300 nm is a benzophenone compound. The optical laminate according to claim 1 or 2, wherein the polarizer has a thickness of 10 μm or less and an iodine concentration of 10% by weight or less. The optical laminate according to any one of claims 1 to 3, wherein the retardation layer has a circularly polarizing function or an elliptically polarizing function. The retardation layer is made of a stretched resin film, and its Re(550) is 100 nm to 200 nm, satisfying the relationship Re(450)<Re(550), and the retardation layer has a slow phase. The optical laminate according to claim 4, wherein the angle between the axis and the absorption axis of the polarizer is 40° to 50°:
Here, Re(450) and Re(550) are in-plane retardations measured with light having wavelengths of 450 nm and 550 nm at 23° C., respectively. The optical laminate according to claim 5, further comprising another retardation layer having a refractive index characteristic of nz>nx=ny on a side opposite to the polarizing plate of the retardation layer. The optical laminate according to any one of claims 1 to 6, wherein a hard coat layer is formed on the pressure-sensitive adhesive layer side of the protective layer. The optical laminate according to claim 1, wherein the adhesive layer has a thickness of 50 μm to 500 μm. An image display device comprising the optical laminate according to claim 1.

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