Optical laminate, and image display device using the same

Abstract

To provide an optical laminate that can achieve a superior black display and white display upon applying to an image display device.SOLUTION: An optical laminate according to an embodiment of the present invention has, in following order,: a polarizing plate that includes a polarizer; a first phase difference layer; and a second phase difference layer. Re (550) of the first phase difference layer is 200 nm to 300 nm, an angle formed with a slow axis of the first phase difference layer and an absorption axis of the polarizer is 10° to 20°, and the first phase difference layer has a relation of Re(450)>Re(550)>Re(650). Re(550) of the second phase difference layer is 100 nm to 200 nm, an angle formed with a slow axis of the second phase difference layer and the absorption axis of the polarizer is 70°to 80°, and the second phase difference layer has a relation of Re(450)≒Re(550)≒Re(650). In one embodiment, the first phase difference layer and / or the second phase difference layer include / includes a pigment compound that exists in a wavelength area equal to or less than 450 nm of a maximum absorption wavelength of an absorption spectrum. In a different embodiment, a color adjustment layer is provided that includes the pigment compound.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices, inorganic EL display devices), have rapidly become widespread. Image display devices often use optical laminates containing a retardation film (e.g., an antireflection film formed by integrating a polarizing plate and a retardation film). When such optical laminates are applied to image display devices, the black display and / or white display may be insufficient. Specifically, the black display may appear reddish or bluish (e.g., purple); and / or the white display may appear greenish, or the brightness of the white display may be insufficient. Therefore, there is a continuing demand for optical laminates that can achieve excellent black display and white display when applied to image display devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-076920 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide an optical laminate that can realize excellent black display and white display when applied to an image display device. [Means for solving the problem]

[0005] [1] An optical laminate according to one embodiment of the present invention comprises, in this order, a polarizing plate including a polarizer, a first retardation layer, and a second retardation layer; the first retardation layer has Re(550) of 200 nm to 300 nm, the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°, and the relationship of Re(450)>Re(550)>Re(650) is satisfied; the second retardation layer has Re(550) of 100 nm to 200 nm, the angle between its slow axis and the absorption axis of the polarizer is 70° to 80°, and the relationship of Re(450)≒Re(550)≒Re(650) is satisfied; and the first retardation layer and / or the second retardation layer contains a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength region of 450 nm or less. [2] Another embodiment of the optical laminate of the present invention includes a polarizing plate including a polarizer, a first retardation layer, a second retardation layer, and a color-adjusting layer; the first retardation layer has Re(550) of 200 nm to 300 nm, the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°, and the relationship of Re(450)>Re(550)>Re(650) is satisfied; the second retardation layer has Re(550) of 100 nm to 200 nm, the angle between its slow axis and the absorption axis of the polarizer is 70° to 80°, and the relationship of Re(450)≒Re(550)≒Re(650) is satisfied; and the color-adjusting layer includes a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength region of 450 nm or less. [3] In the above [2], the optical laminate has the polarizing plate, the color-adjusting layer, the first retardation layer, and the second retardation layer in this order. [4] In the above [2], the optical laminate has the polarizing plate, the first retardation layer, the second retardation layer, and the color-adjusting layer in this order. [5] In the above [2], the optical laminate has the color-adjusting layer, the polarizing plate, the first retardation layer, and the second retardation layer in this order. [6] In any one of the above [1] to [5], the first retardation layer is a liquid crystal alignment solidified layer, and the second retardation layer is a stretched resin film. [7] In any of the above [1] to [6], the maximum ellipticity of the optical laminate in the wavelength range of 380 nm to 780 nm is E MAX , the minimum ellipticity is E MIN When the above optical laminate satisfies the following formula: E MAX / E MIN >3.0. [8] In [7] above, the minimum ellipticity E MIN exists in the wavelength range of 380 nm to 450 nm. [9] According to another aspect of the present invention, there is provided an image display device, which includes the optical laminate according to any one of [1] to [8] above. [Effects of the Invention]

[0006] According to the embodiment of the present invention, an optical laminate that can realize excellent black display and white display when applied to an image display device can be realized. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. [Figure 3] FIG. 10 is a schematic cross-sectional view of an optical laminate according to yet another embodiment of the present invention. [Figure 4] FIG. 10 is a schematic cross-sectional view of an optical laminate according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] (Definition of terms and symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation of a film measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation of a film measured with light of wavelength 550 nm at 23°C. Re(λ) is calculated by the formula: Re=(nx-ny)×d, where d(nm) is the thickness of the film. (3) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction of a film measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction of a film measured with light of wavelength 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth=(nx-nz)×d, where d (nm) is the thickness of the film. (4) Nz coefficient The Nz coefficient is calculated by Nz=Rth / Re. (5)Angle When angles are referred to herein, unless otherwise specified, the angles include angles in both clockwise and counterclockwise directions, for example, "45°" means ±45°.

[0010] A. 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 polarizing plate 10, a first retardation layer 21, and a second retardation layer 22, in this order from the top of the drawing. The top of the drawing is the viewing side, and the bottom of the drawing is the image display panel side. The polarizing plate 10 typically includes a polarizer 11 and protective layers 12 and 13 disposed on both sides of the polarizer 11. Depending on the purpose, at least one of the protective layers 12 and 13 may be omitted. Therefore, the polarizing plate may be a so-called double-protected polarizing plate, a so-called single-protected polarizing plate, or may be composed of a polarizer alone. The layers constituting the optical laminate are laminated via an adhesive layer (e.g., an adhesive layer or a pressure-sensitive adhesive layer; not shown).

[0011] The first retardation layer 21 can typically function as a λ / 2 plate. The Re(550) of the first retardation layer is typically 200 nm to 300 nm, preferably 220 nm to 290 nm, more preferably 240 nm to 280 nm, and even more preferably 260 nm to 275 nm. The angle between the slow axis of the first retardation layer 21 and the absorption axis of the polarizer 11 (hereinafter sometimes referred to as the slow axis angle) is typically 10° to 20°, preferably 12° to 18°, more preferably 13° to 17°, and even more preferably 14° to 16°. Furthermore, the first retardation layer typically exhibits positive wavelength dispersion characteristics in which the retardation value decreases depending on the wavelength of the measurement light. Therefore, the first retardation layer has the relationship Re(450)>Re(550)>Re(650). The first retardation layer is typically a liquid crystal alignment solidified layer. In this specification, the term "liquid crystal alignment solidified layer" refers to a layer in which liquid crystal compounds are aligned in a predetermined direction within the layer and the alignment state is fixed. The term "liquid crystal alignment solidified layer" is a concept that encompasses an alignment hardened layer obtained by hardening a liquid crystal monomer. The specific structure of the first retardation layer will be described in Section C below.

[0012] The second retardation layer 22 can typically function as a λ / 4 plate. Re(550) of the second retardation layer is typically 100 nm to 200 nm, preferably 110 nm to 180 nm, more preferably 120 nm to 170 nm, and still more preferably 130 nm to 150 nm. The slow axis angle of the second retardation layer 22 is typically 70° to 80°, preferably 72° to 78°, more preferably 73° to 77°, and still more preferably 74° to 76°. Further, the second retardation layer typically exhibits flat wavelength dispersion characteristics in which the retardation value hardly changes depending on the wavelength of the measurement light. Therefore, the second retardation layer has a relationship of Re(450) ≒ Re(550) ≒ Re(650). The second retardation layer is typically a stretched film of a resin film. The specific configuration of the second retardation layer will be described in Section D below.

[0013] The first retardation layer and the second retardation layer each having the in-plane retardation and the slow axis direction as described above, as a laminate thereof, can exhibit a circular polarization function or an elliptical polarization function in combination with a polarizer, and can show a relationship of Re(450) < Re(550) < Re(650). Therefore, the optical laminate can function as an antireflection film for an image display device. Note that the arrangement order of the first retardation layer and the second retardation layer may be reversed, and the angle formed by the slow axis of the first retardation layer and the absorption axis of the polarizer and the angle formed by the slow axis of the second retardation layer and the absorption axis of the polarizer may be reversed.

[0014] In the present embodiment, the first retardation layer and / or the second retardation layer contains a dye compound (hereinafter sometimes simply referred to as a dye compound) whose maximum absorption wavelength of the absorption spectrum exists in a wavelength region of 450 nm or less.

[0015] In an embodiment of the present invention, instead of incorporating a dye compound into the first retardation layer and / or the second retardation layer, a color-adjusting layer containing a dye compound may be provided. The color-adjusting layer may be provided at an appropriate position depending on the purpose. For example, the optical stack 101 in FIG. 2 has a polarizing plate 10, a color-adjusting layer 30, a first retardation layer 21, and a second retardation layer 22, in this order from the viewing side; the optical stack 102 in FIG. 3 has a polarizing plate 10, a first retardation layer 21, a second retardation layer 22, and a color-adjusting layer 30, in this order from the viewing side; and the optical stack 103 in FIG. 4 has a color-adjusting layer 30, a polarizing plate 10, a first retardation layer 21, and a second retardation layer 22, in this order from the viewing side.

[0016] According to an embodiment of the present invention, an optical laminate having a first retardation layer exhibiting positive wavelength dispersion characteristics and capable of functioning as a λ / 2 plate and a second retardation layer exhibiting flat wavelength dispersion characteristics and capable of functioning as a λ / 4 plate can be realized by introducing a dye compound into the first retardation layer and / or the second retardation layer, or by providing a color-adjusting layer containing a dye compound. This optical laminate can achieve excellent black and white display when applied to an image display device. More specifically, this is as follows. By combining a first retardation layer exhibiting positive wavelength dispersion characteristics with a second retardation layer exhibiting flat wavelength dispersion characteristics, the degree of deviation from perfect circular polarization increases toward shorter wavelengths due to the combined wavelength dispersion characteristics. As a result, it is possible to intentionally design wavelengths in the short wavelength range (e.g., 450 nm or shorter) that significantly deviate from circular polarization and increase light leakage. This design concept differs from conventional design concepts. In other words, conventional design concepts are designed to create a state as close to circular polarization as possible (ideal reverse-dispersion wavelength dispersion characteristics) across the entire visible light wavelength range. In reality, even based on such a design concept, it is difficult to realize ideal wavelength dispersion characteristics of reverse dispersion, and black display is often insufficient (for example, a reddish or purplish bluish color). Attempting to address this problem may result in a problem of white display being insufficient (for example, a greenish color or insufficient brightness). In contrast, according to an embodiment of the present invention, by intentionally designing a wavelength in the short wavelength region that significantly deviates from circular polarization and increases light leakage, and further introducing the above-mentioned specific dye compound into the components of the optical laminate (substantially the first retardation layer and / or the second retardation layer, or the color-adjusting layer), it is possible to effectively suppress light leakage in the short wavelength region, and as a result, it is possible to achieve excellent black display and white display.

[0017] As described above, the first retardation layer is typically a liquid crystal alignment solidified layer, and the second retardation layer is typically a stretched resin film. This configuration can provide the following advantages: (i) Because a liquid crystal alignment solidified layer exhibiting flat wavelength dispersion characteristics has not yet been put to practical use, using a stretched resin film for the second retardation layer can achieve a combination of a first retardation layer exhibiting positive wavelength dispersion characteristics and a second retardation layer exhibiting flat wavelength dispersion characteristics. Furthermore, compared to a configuration in which both the first retardation layer and the second retardation layer are liquid crystal alignment solidified layers, the following advantages can be achieved: (ii) The occurrence of cracks in the optical laminate (particularly the first retardation layer and the second retardation layer) can be significantly suppressed. (iii) Interference at the interface between the first retardation layer and the adhesive layer and at the interface between the second retardation layer and the adhesive layer, both of which are caused by the thickness and refractive index of the liquid crystal alignment solidified layer, is significantly suppressed, resulting in an optical laminate with excellent appearance.

[0018] In one embodiment, the maximum ellipticity of the optical laminate in the wavelength range of 380 nm to 780 nm is E MAX , the minimum ellipticity is E MIN When the above optical laminate is set as above, it is preferable that the following formula is satisfied. E MAX / E MIN >3.0 E MAX / E MIN is preferably 3.1 or more, more preferably 3.2 or more, even more preferably 3.3 or more, and particularly preferably 3.4 or more. MAX / E MIN According to an embodiment of the present invention, by combining a first retardation layer exhibiting a positive wavelength dispersion characteristic with a second retardation layer exhibiting a flat wavelength dispersion characteristic and intentionally designing a wavelength that is significantly deviated from circularly polarized light in the short wavelength region, such E MAX / E MIN can be realized. E MIN is present in the wavelength range of preferably 380 nm to 450 nm, more preferably 380 nm to 430 nm, and even more preferably 380 nm to 410 nm. MINIf the wavelength is longer than the wavelength range, the desired white display may not be achieved when the optical laminate is applied to an image display device. In this specification, "ellipticity" is an index that indicates whether light (polarized light) is close to circularly polarized light or linearly polarized light. An ellipticity of 1 essentially means circularly polarized light, and the smaller the ellipticity, the more elongated the ellipsoidal polarized light becomes, and an ellipticity of 0 essentially means linearly polarized light.

[0019] In practice, the optical laminate has a pressure-sensitive adhesive layer (not shown) as the outermost layer on the second retardation layer side (image display panel side), so that it can be attached to the image display panel. In this case, it is preferable that a release liner is temporarily attached to the surface of the pressure-sensitive adhesive layer until the optical laminate is used. Temporarily attaching the release liner protects the pressure-sensitive adhesive layer and enables the optical laminate to be formed into a roll.

[0020] The components of the optical laminate will be specifically described below.

[0021] B. Polarizing plate B-1.Polarizer The polarizer 11 is typically made of a polyvinyl alcohol (PVA) resin film containing a dichroic substance (e.g., iodine). Examples of PVA resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0022] The PVA resin preferably contains an acetoacetyl-modified PVA resin. With this configuration, a polarizer having desired mechanical strength can be obtained. The amount of the acetoacetyl-modified PVA resin is preferably 5% by weight to 20% by weight, and more preferably 8% by weight to 12% by weight, based on 100% by weight of the entire PVA resin. If the amount is within this range, a polarizer having better mechanical strength can be obtained.

[0023] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as a halide). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The content of the halide in the polarizer is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of the PVA-based resin. In the manufacturing method described below, the halide is blended into a coating liquid that forms a PVA-based resin layer, which is a precursor of the polarizer, and can be finally introduced into the polarizer. Introducing a halide into the polarizer can improve the orientation of PVA molecules in the polarizer, thereby achieving a polarizer with excellent optical properties (typically, both a high degree of polarization and a high single-unit transmittance).

[0024] The polarizer preferably exhibits absorptive dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is preferably 41.0% to 46.0%, and more preferably 42.0% to 45.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. According to an 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.

[0025] The thickness of the polarizer is, for example, 12 μm or less, preferably 10 μm or less, more preferably 1 μm to 8 μm, and even more preferably 3 μm to 7 μm. By combining such a thin polarizer with a liquid crystal alignment solidified layer, it is possible to significantly reduce the thickness of the optical laminate. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be effectively suppressed and good appearance durability during heating can be obtained.

[0026] The polarizer can be produced by any appropriate method. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0027] Specific examples of polarizers made of a single-layer resin film include hydrophilic polymer films such as PVA films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with iodine or a dichroic substance such as a dichroic dye and stretched, and polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films. A polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred because of its excellent optical properties.

[0028] The dyeing with iodine is carried out, for example, by immersing the PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA film may be stretched and then dyed. If necessary, the PVA film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA film in water and washing it before dyeing, it is possible to wash away dirt and antiblocking agents on the surface of the PVA film, and also to swell the PVA film, thereby preventing uneven dyeing.

[0029] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in a boric acid aqueous solution and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment by heating while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA, even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through treatment steps in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through the drying shrinkage treatment.The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or any suitable protective layer may be laminated on the surface obtained by peeling the resin substrate from the resin substrate / polarizer laminate or on the surface opposite to the peeled surface, depending on the purpose. Details of the method for producing such a polarizer are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0030] B-2.Protective layer The protective layers 12 and 13 are made of any suitable resin film. Typical materials for the resin film include cellulose-based resins such as triacetyl cellulose (TAC), cycloolefin-based resins such as polynorbornene, (meth)acrylic resins, polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin-based resins such as polyethylene, and polycarbonate-based resins. A typical example of a (meth)acrylic resin is a (meth)acrylic resin having a lactone ring structure. Examples of (meth)acrylic resins having a lactone ring structure are described in, for example, JP 2000-230016 A, JP 2001-151814 A, JP 2002-120326 A, JP 2002-254544 A, and JP 2005-146084 A. These publications are incorporated herein by reference. From the viewpoint of ease of processing into modified shapes, etc., cellulose-based resins are preferred, and TAC is more preferred. From the viewpoint of obtaining a polarizing plate with low moisture permeability and excellent durability, cycloolefin-based resins and (meth)acrylic resins are preferred.

[0031] The optical laminate is typically disposed on the viewing side of an image display device, and the protective layer 12 is typically disposed on the viewing side. Therefore, the protective layer 12 may be subjected to a surface treatment as needed. Examples of surface treatments include hard coating, anti-reflection, anti-sticking, and anti-glare treatments. Additionally / alternatively, the protective layer 12 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, by imparting an (elliptical) polarization function or an ultra-high phase difference) as needed. By performing such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the optical laminate may also be suitably applied to image display devices that can be used outdoors.

[0032] In one embodiment, the protective layer 13 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the retardation Rth(550) in the thickness direction is -10 nm to +10 nm.

[0033] The thickness of each of the protective layers 12 and 13 is preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm. If the protective layer 12 has been surface-treated, the thickness of the protective layer 12 includes the thickness of the surface-treated layer.

[0034] C. First retardation layer As described above, the first retardation layer 21 can typically function as a λ / 2 plate. The Re(550) and slow axis angle of the first retardation layer are as explained in Section A above. Furthermore, as described above, the first retardation layer typically exhibits positive wavelength dispersion characteristics. The Re(450) / Re(550) of the first retardation layer is preferably 1.04 to 1.20, more preferably 1.08 to 1.16, and even more preferably 1.10 to 1.14. The Re(650) / Re(550) is preferably 0.85 to 0.98, and more preferably 0.91 to 0.95.

[0035] As described above, the first retardation layer is typically a liquid crystal alignment solidified layer. Examples of liquid crystal compounds used in the liquid crystal alignment solidified layer include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable (i.e., a liquid crystal monomer). 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 crystal. Therefore, the formed liquid crystal alignment solidified layer does not undergo, for example, a transition to a liquid crystal phase, a glass phase, or a crystalline phase due to temperature changes, which is unique to liquid crystal compounds. As a result, the liquid crystal alignment solidified layer becomes a retardation layer that is not affected by temperature changes and has extremely excellent stability.

[0036] In one embodiment, the liquid crystal alignment solidified layer can be formed using a composition containing a polymerizable liquid crystal compound (polymerizable liquid crystal compound, i.e., liquid crystal monomer). In this specification, the polymerizable liquid crystal compound contained in the composition refers to a compound having a polymerizable group and liquid crystallinity. The polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical or acid generated from a photopolymerization initiator. Examples of liquid crystal monomers that can be used include polymerizable mesogen compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US Pat. No. 5,211,877), EP 66137 (US Pat. No. 4,388,453), WO 93 / 22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) from BASF, E7 (trade name) from Merck, and LC-Sillicon-CC3767 (trade name) from Wacker-Chem.

[0037] The mechanism by which the liquid crystal compound exhibits liquid crystallinity may be thermotropic or lyotropic. The liquid crystal phase may be nematic or smectic. From the viewpoint of ease of production, the liquid crystallinity is preferably thermotropic nematic liquid crystal.

[0038] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type of the liquid crystal monomer. 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.

[0039] The birefringence Δn of the liquid crystal alignment solidified layer is preferably 0.06 or more, more preferably 0.08 or more, even more preferably 0.09 or more, and particularly preferably 0.10 or more. The upper limit of Δn may be, for example, 0.13, or may be, for example, 0.12. If Δn is within this range, the desired in-plane retardation can be achieved with a very thin thickness. As a result, the liquid crystal alignment solidified layer and the optical laminate can be made even thinner, which can ultimately contribute to significantly thinner image display devices.

[0040] The thickness of the first retardation layer can be adjusted to obtain an in-plane retardation sufficient to function as a λ / 2 plate. By configuring the first retardation layer using a liquid crystal alignment solidified layer, the thickness required to obtain a desired in-plane retardation can be significantly reduced compared to using a stretched resin film. Since a λ / 2 plate is thicker than a λ / 4 plate, configuring the λ / 2 plate using a liquid crystal alignment solidified layer significantly contributes to thinner screens. Therefore, the combined use of a liquid crystal alignment solidified layer (positive wavelength dispersion characteristics) and a stretched resin film (flat wavelength dispersion characteristics) can contribute to thinner screens while maintaining the above-described effects. In one embodiment, the thickness of the first retardation layer can be, for example, 2.0 μm to 4.0 μm. In another embodiment, the thickness of the first retardation layer is preferably 1.7 μm or less, more preferably 1.6 μm or less, and even more preferably 1.5 μm or less. In this case, the thickness of the first retardation layer can be, for example, 1.3 μm or more. As described above, according to the embodiment of the present invention, it is possible to realize an optical laminate that can realize excellent black display and white display when applied to an image display device, while making the thickness of the first retardation layer thinner than that of a conventional liquid crystal alignment solidified layer.

[0041] D.Second retardation layer As described above, the second retardation layer 22 can typically function as a λ / 4 plate. The Re(550) and slow axis angle of the second retardation layer are as described in Section A above. Furthermore, as described above, the second retardation layer typically exhibits flat wavelength dispersion characteristics. The Re(450) / Re(550) of the second retardation layer is preferably 0.98 to 1.02, more preferably 0.99 to 1.01. The Re(650) / Re(550) is preferably 0.98 to 1.02, more preferably 0.99 to 1.01.

[0042] As described above, the second retardation layer is typically a stretched resin film. As the resin constituting the resin film, any suitable resin can be used as long as it can satisfy the above-mentioned characteristics. Typical examples of such resins include cyclic olefin resins and polycarbonate resins. These resins can exhibit flat wavelength dispersion characteristics.

[0043] Cyclic olefin resin is a general term for resins polymerized using cyclic olefins as polymerization units, and examples thereof include those described in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. Specific examples include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins with α-olefins such as ethylene and propylene, graft-modified products of these copolymers modified with unsaturated carboxylic acids or their derivatives, and hydrogenated products thereof. Specific examples of cyclic olefins include norbornene-based monomers. Examples of norbornene-based monomers include those described in JP-A-2015-210459. Various cyclic olefin-based resin products are commercially available. Specific examples include Zeon Corporation's trade names "Zeonex" and "Zeonor," JSR Corporation's trade name "Arton," TICONA Corporation's trade name "Topas," and Mitsui Chemicals' trade name "APEL."

[0044] Any suitable polycarbonate resin can be used as the polycarbonate resin as long as the effects of the present invention can be achieved. Preferably, the polycarbonate resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri-, or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol, and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds as needed. Details of polycarbonate resins that can be suitably used in the present invention are described in, for example, JP-A Nos. 2014-10291 and 2014-26266, the disclosures of which are incorporated herein by reference.

[0045] The second retardation layer can be obtained by forming a film from the above-mentioned resin and then stretching the film.By appropriately adjusting the type, number, combination and compounding ratio of the monomer components of the above-mentioned resin, stretching method (for example, free-end uniaxial stretching, fixed-end uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, oblique stretching), and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction), the second retardation layer can be obtained with desired optical properties (for example, refractive index properties, in-plane retardation, slow axis angle).

[0046] The thickness of the second retardation layer can be adjusted so as to obtain an in-plane retardation that enables it to function as a λ / 4 plate. The thickness of the second retardation layer is preferably 15 μm to 60 μm, more preferably 20 μm to 55 μm, and most preferably 25 μm to 50 μm.

[0047] E. Pigment Compounds In an embodiment of the present invention, as described above, the first retardation layer and / or the second retardation layer may contain a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength region of 450 nm or less. According to an embodiment of the present invention, by incorporating such a dye compound into an optical laminate including a first retardation layer exhibiting positive wavelength dispersion characteristics and a second retardation layer exhibiting flat wavelength dispersion characteristics, an optical laminate that can achieve excellent black and white display when applied to an image display device can be obtained. The dye compound may be a compound having an absorption spectrum with a specific half-width in a specific wavelength region of 450 nm or less, or may be a compound that absorbs light over the entire wavelength region of 450 nm or less (essentially, an ultraviolet absorber). Therefore, in this specification, the term "dye compound" encompasses ultraviolet absorbers. For convenience, in the following description of Section E, a compound having an absorption spectrum with a specific half-width in a specific wavelength region of 450 nm or less will be described as a dye compound, followed by a description of ultraviolet absorbers. Meanwhile, throughout this specification, as described above, the term "dye compound" encompasses ultraviolet absorbers.

[0048] The dye compound has an absorption spectrum with a maximum absorption wavelength preferably in the wavelength range of 380 nm to 430 nm, more preferably in the wavelength range of 390 nm to 410 nm. By using such a dye compound, the above-described effects of the embodiment of the present invention can be enhanced. Furthermore, the dye compound can sufficiently absorb light in a range that does not affect image display (for example, the self-emission of an organic EL panel, or image display by a backlight and a liquid crystal panel). As a result, the degradation of the first retardation layer and the second retardation layer can be suppressed without adversely affecting image display performance.

[0049] The half-width of the dye compound is preferably 80 nm or less, more preferably 5 nm to 70 nm, and even more preferably 10 nm to 60 nm. A half-width within this range allows sufficient absorption of light in a range that does not affect image display, while allowing sufficient transmission of light on the long wavelength side required for image display devices. The half-width of the dye compound can be measured from the transmission absorption spectrum of a solution of the dye compound using an ultraviolet-visible spectrophotometer (U-4100, manufactured by Hitachi High-Tech Science Corporation) under the following conditions. Typically, the half-width of the dye compound is determined by adjusting the concentration so that the absorbance at the maximum absorption wavelength is 1.0, and the wavelength interval (full width at half maximum) between two points at 50% of the peak value is taken as the half-width of the dye compound. (Measurement conditions) Solvent: toluene or chloroform Cell: Quartz cell Optical path length: 10mm

[0050] Any suitable dye compound may be used as long as the maximum absorption wavelength of the absorption spectrum is within the above wavelength range. Examples of the dye compound include organic dye compounds and inorganic dye compounds. Organic dye compounds are preferred. Organic dye compounds can have excellent dispersibility and transparency.

[0051] Examples of organic dye compounds include azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, and porphyrin compounds.

[0052] As the organic dye compound, commercially available products can be suitably used. Specific examples of the indole-based compound include BONASORB UA3911 (trade name, absorption spectrum: maximum absorption wavelength: 398 nm, half-width: 48 nm, manufactured by Orient Chemical Industrial Co., Ltd.) and BONASORB UA3912 (trade name, absorption spectrum: maximum absorption wavelength: 386 nm, half-width: 53 nm, manufactured by Orient Chemical Industrial Co., Ltd.); an example of the cinnamic acid-based compound is SOM-5-0106 (trade name, absorption spectrum: maximum absorption wavelength: 416 nm, half-width: 50 nm, manufactured by Orient Chemical Industrial Co., Ltd.); and an example of the porphyrin-based compound is FDB-001 (trade name, absorption spectrum: maximum absorption wavelength: 420 nm, half-width: 14 nm, manufactured by Yamada Chemical Industry Co., Ltd.).

[0053] Any suitable ultraviolet absorber can be used as the ultraviolet absorber. Specific examples include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. These can be used alone or in combination of two or more. Among these, triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred. At least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having two or less hydroxyl groups per molecule and benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton per molecule is preferred because it has good solubility in the monomers used to form the acrylic pressure-sensitive adhesive composition and has high ultraviolet absorption ability at a wavelength of around 380 nm.

[0054] The dye compound or the UV absorber may be used alone or in combination of two or more. The dye compound and the UV absorber may be used in combination. The content of the dye compound and / or the UV absorber in the first retardation layer or the second retardation layer is preferably 0.1 to 80 parts by weight relative to 100 parts by weight of the liquid crystal compound. When the dye compound is contained in both the first retardation layer and the second retardation layer, the total content may be within the above range.

[0055] F. Color adjustment layer In an embodiment of the present invention, instead of introducing a dye compound into the first retardation layer and / or the second retardation layer as described above, a color-adjusting layer containing a dye compound may be provided. The color-adjusting layer may have any appropriate configuration as long as it contains the dye compound described in Section E above and can achieve the effects of the embodiment of the present invention. For example, the color-adjusting layer may be made of a resin film, a pressure-sensitive adhesive, or an active energy ray-curable adhesive.

[0056] When the color-adjusting layer is made of a resin film, it typically contains a binder resin (film-forming component) and the above-mentioned dye compound. Typical examples of binder resins include polycarbonate-based resins, cyclic olefin-based resins, cellulose-based resins, polyester-based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, and acrylic-based resins. In this embodiment, the color-adjusting layer can be formed, for example, by applying and drying a solution or dispersion containing the binder resin and the dye compound.

[0057] When the color-adjusting layer is made of an adhesive, the color-adjusting layer can typically be made of an adhesive containing the above-mentioned dye compound. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these, acrylic-based adhesives containing a (meth)acrylic polymer as a base polymer are preferably used.

[0058] The (meth)acrylic polymer contains alkyl (meth)acrylate as a main component as a monomer unit. Examples of alkyl (meth)acrylate include those having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal. The number of carbon atoms in the alkyl group is preferably 2 to 18, more preferably 3 to 10, and even more preferably 4 to 8. The alkyl (meth)acrylate can be used alone or in combination of two or more. Note that "alkyl (meth)acrylate" refers to alkyl acrylate and / or alkyl methacrylate.

[0059] The alkyl (meth)acrylate preferably accounts for 40% by weight or more, more preferably 50% by weight or more, and even more preferably 60% by weight or more, of the total amount of monomer components forming the (meth)acrylic polymer.

[0060] The monomer component may include a copolymerizable monomer copolymerizable with the alkyl (meth)acrylate. The copolymerizable monomer can be used as the remainder of the alkyl (meth)acrylate in the monomer component. Examples of the copolymerizable monomer include carboxyl group-containing monomers, hydroxyl group-containing monomers, monomers having a cyclic ether group, cyclic nitrogen-containing monomers, amino group-containing monomers, amide group-containing monomers, polyfunctional monomers, cyclopolymerizable monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, (meth)acrylic acid esters having an alicyclic hydrocarbon group, (meth)acrylic acid esters having an aromatic hydrocarbon group, vinyl esters, aromatic vinyl compounds, olefins, dienes, and vinyl ethers. The copolymerizable monomers may be used alone or in combination of two or more.

[0061] The weight-average molecular weight of the (meth)acrylic polymer is preferably 500,000 to 3,000,000, more preferably 700,000 to 2,700,000, and even more preferably 800,000 to 2,500,000. With this configuration, a color-adjusting layer with excellent durability (particularly heat resistance) can be obtained. The weight-average molecular weight is measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

[0062] The adhesive may further contain a crosslinking agent, and may further contain a silane coupling agent and / or additives as needed. Specific examples of additives include colorants, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particulates, and foil-like materials. Furthermore, a redox system may be used by adding a reducing agent within a controllable range. The type, number, combination, and compounding ratio of the crosslinking agent, silane coupling agent, and additives may be appropriately determined depending on the purpose.

[0063] By adjusting the types, numbers, combinations and compounding ratios of the base polymers that form the adhesive, as well as the types, numbers, combinations and compounding ratios of the crosslinking agent, silane coupling agent and additives, a color-adjusting layer having the desired properties according to the purpose can be obtained.

[0064] When the color-adjusting layer is composed of an active energy ray-curable adhesive, the color-adjusting layer may typically be composed of an active energy ray-curable adhesive containing the above-mentioned dye compound. Examples of active energy ray-curable adhesives include radical-curable adhesives, cation-curable adhesives, anion-curable adhesives, and hybrids of radical-curable adhesives and cation-curable adhesives. The active energy ray-curable adhesive typically contains a monofunctional component, a polyfunctional component, and a photopolymerization initiator. The monofunctional component and the polyfunctional component are typically radically polymerizable compounds. Preferred examples of the monofunctional component and the polyfunctional component include an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, an oxetanyl group, and derivatives thereof.

[0065] The content of the dye compound in the color-adjusting layer is preferably 0.01 to 100 parts by weight relative to 100 parts by weight of the base polymer or binder resin. If the content of the dye compound is too low, the effects of the present invention may not be fully achieved. If the content of the dye compound is too high, the white display may appear greenish or the brightness of the white display may be insufficient.

[0066] The thickness of the color-adjusting layer is preferably 5 μm to 20 μm, more preferably 6 μm to 15 μm, and even more preferably 8 μm to 12 μm.

[0067] G. Image display device The optical laminates described in the above items A to F can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such optical laminates. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical laminates described in the above items A to F on the viewing side. [Example]

[0068] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Measurement and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0069] (1) Hue The optical film on the viewing side of a commercially available organic EL display device (manufactured by Samsung, product name "GALAXY S5") was removed, and the removed surface was cleaned. The optical laminates obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were then bonded via an adhesive to obtain an organic EL display device. The optical laminates of Examples 5 to 8 were bonded via a color adjustment layer to obtain an organic EL display device. The obtained organic EL display device was used as a test sample. The test sample was measured for a black display and a white display in the SCE method using a spectrophotometer (manufactured by Konica Minolta, product name "CM-2600d") * value and b * The values ​​were measured, and the display state was also visually observed.

[0070] (2) Brightness A test sample was obtained in the same manner as in "(1) Hue" above. The front luminance of the test sample in black display and white display was measured using a spectroradiometer manufactured by TOPCON Corporation (product name "SR-UL1R").

[0071] (3) Ellipticity The optical laminates obtained in the examples and comparative examples were measured using a polarization / phase difference measurement system (manufactured by Axometrics, product name "AxoScan"). Measurements were performed every 10 nm in the wavelength range of 380 nm to 780 nm, and the maximum ellipticity E MAX and the minimum ellipticity E MIN Furthermore, the minimum ellipticity E MIN The measurement wavelength was determined.

[0072] [Production Example 1: Preparation of Liquid Crystal Alignment Solidified Layer A Constituting First Retardation Layer] A photopolymerizable liquid crystal compound exhibiting a nematic liquid crystal phase (BASF "Paliocolor LC242"; chemical formula below) was dissolved in cyclopentanone to prepare a solution with a solids concentration of 30 wt%. A surfactant (BYK-Chemie "BYK-360") and a photopolymerization initiator (IGM Resins "Omnirad907") were added to the solution to prepare a liquid crystal composition solution. The surfactant and initiator were added in amounts of 0.01 and 3 wt%, respectively, per 100 wt parts of the photopolymerizable liquid crystal compound. A biaxially stretched norbornene-based film (Zeon Corporation "ZEONOR Film"; thickness: 33 μm, Re(550) = 135 nm) was prepared as a substrate. The liquid crystal composition was applied to the substrate using a bar coater to achieve a Re(550) of 270 nm and then heated at 100°C for 3 minutes to align the liquid crystal. After cooling to room temperature, the device was irradiated with an integrated light dose of 400 mJ / cm under a nitrogen atmosphere. 2 The layer was then photocured by irradiating it with ultraviolet light, yielding a laminate having a substrate / solidified liquid crystal alignment layer A. The liquid crystal alignment layer A was homogeneously oriented, exhibited a refractive index characteristic of nx>ny=nz, and had a thickness of 3.2 μm. The Re(450) / Re(550) of the liquid crystal alignment layer A was 1.08, and the Re(650) / Re(550) was 0.95, indicating positive wavelength dispersion characteristics. [ka]

[0073] [Production Example 2: Production of Retardation Film B Constituting Second Retardation Layer] A commercially available cycloolefin resin film (Kaneka Corporation, product name "UTZ-Film #140") was used as is as retardation film B. The Re(550) of retardation film B was 140 nm. The Re(450) / Re(550) of the obtained retardation film B was 0.98, and the Re(650) / Re(550) was 0.99, indicating flat wavelength dispersion characteristics.

[0074] [Production Example 3: Preparation of Liquid Crystal Alignment Solidified Layer C] A laminate having a substrate / liquid crystal alignment solidified layer C was obtained in the same manner as in Manufacturing Example 4 of JP 2020-3650 A. The discotic liquid crystal compound in liquid crystal alignment solidified layer C was vertically aligned, exhibiting a refractive index characteristic of nx = nz > ny, Re(550) of 270 nm, and a thickness of 2.2 μm. Furthermore, the Re(450) / Re(550) of liquid crystal alignment solidified layer D was 1.09, and the Re(650) / Re(550) was 0.96, indicating positive wavelength dispersion characteristics.

[0075] [Production Example 4: Preparation of Liquid Crystal Alignment Solidified Layer D] A laminate having a substrate / liquid crystal alignment solidified layer D structure was obtained in the same manner as in Production Example 1, except that the coating thickness was changed so that Re(550) was 140 nm. The liquid crystal alignment solidified layer D was homogeneously oriented, exhibited a refractive index characteristic of nx>ny=nz, and had a thickness of 1.7 μm. Furthermore, the Re(450) / Re(550) of the liquid crystal alignment solidified layer D was 1.08, and the Re(650) / Re(550) was 0.95, indicating positive wavelength dispersion characteristics.

[0076] [Production Example 5: Preparation of Liquid Crystal Alignment Solidified Layer E] A laminate having a substrate / liquid crystal alignment solidified layer E structure was obtained in the same manner as in Production Example 1, except that the coating thickness was changed so that Re(550) was 220 nm. The liquid crystal alignment solidified layer E was homogeneously oriented, exhibited a refractive index characteristic of nx>ny=nz, and had a thickness of 2.6 μm. The liquid crystal alignment solidified layer E also had Re(450) / Re(550) of 1.08 and Re(650) / Re(550) of 0.95, indicating positive wavelength dispersion characteristics.

[0077] [Production Example 6: Production of Retardation Film F] A commercially available cycloolefin resin film (manufactured by Kaneka Corporation, product name "UTZ-Film #110") was used as the retardation film F. The Re(550) of the retardation film F was 110 nm. The Re(450) / Re(550) of the retardation film F was 0.98, and the Re(650) / Re(550) was 0.99, indicating flat wavelength dispersion characteristics.

[0078] [Production Example 7: Preparation of Liquid Crystal Alignment Solidified Layer G] A laminate having a substrate / liquid crystal alignment solidified layer G structure was obtained in the same manner as in Manufacturing Example 5 of JP 2020-3650 A. The nematic liquid crystal compound in the liquid crystal alignment solidified layer G was horizontally aligned, exhibiting a refractive index characteristic of nx>ny=nz, Re(550) of 140 nm, and a thickness of 1.2 μm. Furthermore, the Re(450) / Re(550) of the liquid crystal alignment solidified layer G was 1.09, and the Re(650) / Re(550) was 0.95, indicating positive wavelength dispersion characteristics.

[0079] [Production Example 8: Preparation of Color Adjusting Layer I] A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 94.9 parts of butyl acrylate, 5 parts of acrylic acid, and 0.1 parts of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts of ethyl acetate were charged to 100 parts of this monomer mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere, and the temperature in the flask was maintained at around 55°C for 8 hours to carry out a polymerization reaction, producing an acrylic polymer solution with a weight-average molecular weight (Mw) of 2.2 million. A dye compound-containing adhesive was obtained by blending 15 parts of a dye compound (Yamada Chemical Co., Ltd., product name "FDB-009": absorption spectrum maximum absorption wavelength 402 nm, half-width 45 nm), 0.6 parts of an isocyanate-based crosslinking agent (trimethylolpropane / tolylene diisocyanate adduct: Tosoh Corporation, product name "Coronate L"), 0.2 parts of a peroxide crosslinking agent (benzoyl peroxide: Nippon Oil & Fats Corporation, product name "Niper BMT"), and 0.2 parts of an epoxy group-containing silane coupling agent (Shin-Etsu Chemical Co., Ltd., product name "KBM-403") per 100 parts of the solid content of the acrylic polymer solution. The resulting dye compound-containing adhesive was applied to a release liner and dried to prepare a color-adjusting layer I having a thickness of 10 μm.

[0080] [Production Example 9: Preparation of Color Adjusting Layer II] A color-adjusting layer II having a thickness of 10 μm was formed on a release liner in the same manner as in Production Example 8, except that the amount of the dye compound was changed from 15 parts to 45 parts.

[0081] [Production Example 10: Preparation of color-adjusting layer III] A color adjustment layer III having a thickness of 10 μm was prepared on a release liner in the same manner as in Production Example 8, except that 5 parts of an ultraviolet absorber (manufactured by BASF, product name "Tinuvin 970") was used instead of 15 parts of the dye compound.

[0082] [Production Example 11: Preparation of color-adjusting layer IV] A color-adjusting layer IV having a thickness of 10 μm was formed on a release liner in the same manner as in Production Example 10, except that the blending amount of the ultraviolet absorber was changed from 5 parts to 15 parts.

[0083] [Production Example 12: Preparation of Color Adjusting Layer V] A color adjustment layer V having a thickness of 10 μm was prepared on a release liner in the same manner as in Production Example 8, except that the dye compound used was "FDB-005" manufactured by Yamada Chemical Co., Ltd. (maximum absorption wavelength of 452 nm, half-width of 64 nm in the absorption spectrum) instead of "FDB-009."

[0084] [Production Example 13: Preparation of color-adjusting layer VI] A color adjustment layer VI having a thickness of 10 μm was prepared on a release liner in the same manner as in Production Example 8, except that the dye compound used was "FDR-003" manufactured by Yamada Chemical Co., Ltd. (maximum absorption wavelength of 699 nm, half-width of 100 nm in the absorption spectrum) instead of "FDB-009."

[0085] [Example 1] 1. Preparation of Polarizing Plates 1-1. Preparation of polarizer A long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin made by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFFIMER") in a 9:1 ratio, to which 13 parts by weight of potassium iodide was added, in water. The above PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment). Next, the sample was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment). Thereafter, the film was dried in an oven maintained at about 90°C, and brought into contact with a heated roll made of SUS whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this way, a polarizer having a thickness of about 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizer structure was obtained. The single transmittance Ts of the polarizer was 43.3%.

[0086] 1-2. Preparation of polarizing plates An HC-COP film was attached to the surface of the obtained polarizer (the surface opposite to the resin substrate) via a UV-curable adhesive. The HC-COP film was a film in which an HC layer (4 μm thick) was formed on a cycloolefin resin (COP) film (25 μm thick), and the COP film was attached to the polarizer side. Next, the resin substrate was peeled off to obtain a polarizing plate having a configuration of HC layer / COP film (protective layer) / polarizer.

[0087] 2. Preparation of optical laminates The color-adjusting layer I from Production Example 8 was transferred to the polarizer surface of the resulting polarizing plate. The liquid crystal alignment solidified layer A from Production Example 1 was then transferred (laminated) through the color-adjusting layer I. The retardation film B from Production Example 2 was then laminated onto the surface of the liquid crystal alignment solidified layer A via a standard acrylic adhesive (15 μm thick). The lamination was performed so that the slow axis direction of the liquid crystal alignment solidified layer A was oriented at 15° to the absorption axis direction of the polarizer, and the slow axis direction of the retardation film B was oriented at 75° to the absorption axis direction of the polarizer. In this way, an optical laminate was prepared having a polarizing plate / color-adjusting layer I / first retardation layer (liquid crystal alignment solidified layer A) / second retardation layer (retardation film B) configuration (configuration shown in Figure 2). The resulting optical laminate was evaluated for the above-mentioned "hue," "brightness," and "ellipticity." The results are shown in Table 1.

[0088] [Examples 2 to 4 and Comparative Examples 1 to 6] An optical laminate was obtained in the same manner as in Example 1, except that the configuration of each layer was changed as shown in Table 1. The obtained optical laminate was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0089] [Example 5] A polarizing plate having a structure of HC layer / COP film (protective layer) / polarizer was obtained in the same manner as in Example 1. The liquid crystal alignment solidified layer A of Production Example 1 was transferred (laminated) onto the polarizer surface of the obtained polarizing plate via a UV-curable adhesive (thickness: 1 μm). The retardation film B of Production Example 2 was laminated onto the surface of the liquid crystal alignment solidified layer A via a conventional acrylic pressure-sensitive adhesive (thickness: 15 μm). The lamination was performed so that the slow axis direction of the liquid crystal alignment solidified layer A was oriented at 15° to the absorption axis direction of the polarizer, and the slow axis direction of the retardation film B was oriented at 75° to the absorption axis direction of the polarizer. Furthermore, the color adjustment layer I of Production Example 8 was transferred onto the surface of the liquid crystal alignment solidified layer A to prepare an optical laminate having a structure of polarizing plate / first retardation layer (liquid crystal alignment solidified layer A) / second retardation layer (retardation film B) / color adjustment layer I (the structure shown in FIG. 3). The obtained optical laminate was subjected to evaluation in the same manner as in Example 1. The results are shown in Table 1.

[0090] [Examples 6 to 8] An optical laminate was obtained in the same manner as in Example 5, except that the configuration of each layer was changed as shown in Table 1. The obtained optical laminate was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[0091] [Table 1]

[0092] [evaluation] As is clear from Table 1, the examples of the present invention provide optical laminates that can achieve excellent black and white display when applied to image display devices. Comparative Example 1, which has a configuration corresponding to the examples of the present invention except for the absence of a dye compound, exhibits a bluish (purple) black display. Comparative Example 2, in which the maximum absorption wavelength of the dye compound is on the long wavelength side, exhibits a greenish white display. Comparative Example 3, in which light leakage occurs on the long wavelength side, exhibits a reddish black display; Comparative Example 4, in which a dye compound is introduced to suppress light leakage, exhibits insufficient brightness in the white display. Comparative Example 5, in which both the first and second retardation layers are formed from liquid crystal alignment solidified layers (positive wavelength dispersion characteristics), exhibits a bluish (purple) black display; and Comparative Example 6, in which a dye compound is introduced into the configuration of Comparative Example 5, exhibits a greenish white display and insufficient brightness. [Industrial Applicability]

[0093] The optical laminate according to the embodiment of the present invention can be suitably used in image display devices (typically, liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0094] 10 Polarizing plate 11 Polarizer 12 Protective layer 13 Protective layer 21 1st retardation layer 22 Second retardation layer 30 color adjustment layer 100 Optical laminate 101 Optical laminate 102 Optical laminate 103 Optical laminate

Claims

1. a polarizing plate including a polarizer, a first retardation layer, and a second retardation layer in this order; The first retardation layer has an Re(550) of 200 nm to 300 nm, an angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is 10° to 20°, and has a relationship of Re(450)>Re(550)>Re(650), The second retardation layer has an Re(550) of 100 nm to 200 nm, an angle between the slow axis of the second retardation layer and the absorption axis of the polarizer is 70° to 80°, and has a relationship of Re(450)≒Re(550)≒Re(650), the first retardation layer and / or the second retardation layer contains a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength region of 450 nm or less; Optical laminate.

2. a polarizing plate including a polarizer, a first retardation layer, a second retardation layer, and a color-adjusting layer; The first retardation layer has an Re(550) of 200 nm to 300 nm, an angle between the slow axis of the first retardation layer and the absorption axis of the polarizer is 10° to 20°, and has a relationship of Re(450)>Re(550)>Re(650), The second retardation layer has an Re(550) of 100 nm to 200 nm, an angle between the slow axis of the second retardation layer and the absorption axis of the polarizer is 70° to 80°, and has a relationship of Re(450)≒Re(550)≒Re(650), the color-modulating layer contains a dye compound whose absorption spectrum has a maximum absorption wavelength in a wavelength region of 450 nm or less; Optical laminate.

3. The optical laminate according to claim 2 , comprising the polarizing plate, the color-adjusting layer, the first retardation layer, and the second retardation layer in this order.

4. The optical laminate according to claim 2 , comprising the polarizing plate, the first retardation layer, the second retardation layer, and the color-adjusting layer in this order.

5. The optical laminate according to claim 2 , comprising the color-adjusting layer, the polarizing plate, the first retardation layer, and the second retardation layer in this order.

6. 3. The optical laminate according to claim 1, wherein the first retardation layer is a liquid crystal alignment solidified layer, and the second retardation layer is a stretched resin film.

7. The maximum ellipticity of the optical laminate in the wavelength range of 380 nm to 780 nm is E ＭＡＸ , the minimum ellipticity is E ＭＩＮ 3. The optical laminate according to claim 1 or 2, which satisfies the following formula: E ＭＡＸ / E ＭＩＮ >3.0。

8. The minimum ellipticity E ＭＩＮ The optical laminate according to claim 7, wherein the wavelength of the light is in the range of 380 nm to 450 nm.

9. An image display device comprising the optical laminate according to claim 1 or 2.

Images