Polarizing plate with optical compensation layer, method for manufacturing same, and image display device

Abstract

Provided is a polarizing plate with an optical compensation layer in which reflection in an oblique direction in black display can be suppressed and redness of hue in the oblique direction can be suppressed. A polarizing plate with an optical compensation layer according to an embodiment of the present invention comprises a polarizer, a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer. The first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer each exhibit a refractive index characteristic satisfying nx > nz > ny, and satisfy 1.10 < Re(450) / Re(550) ≤ 1.40. The Nz coefficient of the first optical compensation layer is 0.10-0.4 or 0.65-0.85. The Nz coefficients of the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer are each 0.40-0.60.

Description

Polarizing plate with optical compensation layer, method for producing the same, and image display device

[0001] The present invention relates to a polarizing plate with an optical compensation layer, a method for producing the same, and an image display device.

[0002] In recent years, with the popularization of thin displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Since an organic EL panel has a highly reflective metal layer, it is prone to problems such as external light reflection and background reflection. Therefore, it is known that these problems can be prevented by providing a circularly polarizing plate on the viewing side. As a common circularly polarizing plate, one obtained by laminating a retardation film (typically a λ / 4 plate) such that the slow axis forms an angle of about 45° with respect to the absorption axis of the polarizer is known. In addition, in order to further improve antireflection properties, attempts have been made to laminate retardation films (optical compensation layers) having various optical properties (for example, Patent Document 1). However, in conventional circularly polarizing plates, the reflectance in an oblique direction during black display becomes excessively high, and the hue in an oblique direction may include redness.

[0003] Japanese Patent Application Laid-Open No. 2016-006543

[0004] The present invention has been made to solve the above-described conventional problems, and a main object of the present invention is to provide a polarizing plate with an optical compensation layer that can suppress reflection in an oblique direction during black display and can suppress redness of hue in an oblique direction.

[0005] [1] A polarizing plate with an optical compensation layer according to an embodiment of the present invention comprises a polarizer, a first optical compensation layer disposed adjacent to the polarizer, a second optical compensation layer disposed adjacent to the first optical compensation layer, a third optical compensation layer disposed adjacent to the second optical compensation layer, and a fourth optical compensation layer as the outermost optical compensation layer disposed adjacent to the third optical compensation layer. The first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer all exhibit refractive index characteristics of nx > nz > ny and satisfy 1.10 < Re(450) / Re(550) ≤ 1.40. The Nz coefficient of the first optical compensation layer is 0.10 or more and 0.40 or less or 0.65 or more and 0.85 or less. The Nz coefficients of the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer are all 0.40 or more and 0.60 or less. Here, Re(450) and Re(550) represent the in-plane phase difference measured with light of wavelengths of 450 nm and 550 nm at 23°C, respectively. [2] In [1] above, the polarizing plate with optical compensation layer may satisfy the following conditions for each reflected hue (x, y) at azimuth angles (φ) of 30° and 210°, and at polar angles (Θ) = 42° and 49° at 150° and 330°: 0 < x < 0.35 and 0 < y < 0.35. [3] In [1] or [2] above, the Re(550) of the first optical compensation layer is 190 nm to 310 nm, and the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is in the range of 90° ± 10° or 0° ± 10°; the Re(550) of the second optical compensation layer is 200 nm to 310 nm, and the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer The angle is 80° to 110°; the Re(550) of the third optical compensation layer is 210 nm to 270 nm, and the angle between the absorption axis of the polarizer and the slow axis of the third optical compensation layer is 100° to 130°; the Re(550) of the fourth optical compensation layer is 80 nm to 160 nm, and the angle between the absorption axis of the polarizer and the slow axis of the fourth optical compensation layer may be -20° to 25°.[4] In any of [1] to [3] above, the thickness of the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer may be 0.1 μm or more and less than 10.0 μm. [5] In any of [1] to [4] above, at least one of the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer may contain a liquid crystalline compound. [6] In [5] above, the liquid crystalline compound may contain a compound having photo-alignment properties. [7] In [6] above, the compound having photo-alignment properties may be at least one compound selected from the group consisting of cinnamic acid, cinnamic acid derivatives, azobenzene, azobenzene derivatives, coumarin, coumarin derivatives, chalcone, chalcone derivatives, stilbene, and stilbene derivatives. [8] According to another aspect of the present invention, a method for manufacturing a polarizing plate with an optical compensation layer is provided. The above manufacturing method is a method for manufacturing a polarizing plate with an optical compensation layer according to any of [1] to [7] above, and includes applying a liquid crystalline compound and irradiating the liquid crystalline compound with polarized ultraviolet light to orient it, thereby obtaining at least one of a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer. [9] In [8] above, the manufacturing method may also include bonding the polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer by roll-to-roll.

[10] According to yet another aspect of the present invention, an image display device is provided. The image display device includes a polarizing plate with an optical compensation layer according to any of [1] to [7] above.

[0006] According to embodiments of the present invention, it is possible to realize a polarizing plate with an optical compensation layer that can suppress oblique reflection in black display and suppress the reddish tint of oblique hues.

[0007] This is a schematic cross-sectional view of a polarizing plate with an optical compensation layer according to one embodiment of the present invention.

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

[0009] (Definitions of Terms and Symbols) The 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 refractive index in the plane is maximum (i.e., in the direction of the slow phase axis), "ny" is the refractive index in the direction perpendicular to the slow phase axis in the plane (i.e., in the direction of the fast phase axis), and "nz" is the refractive index in the thickness direction. A phase difference film exhibiting refractive index characteristics nx > nz > ny is called a "Z film". In this specification, a layer (film) having refractive index characteristics nx > nz > ny may also be referred to as a Z film. (2) In-Plane Phase Difference (Re) "Re(λ)" is the in-plane phase difference measured with light of wavelength λnm at 23°C. Re(λ) is calculated by the formula: Re = (nx - ny) × d, where d (nm) is the thickness of the layer (film). For example, "Re(550)" is the in-plane phase difference measured with light of a wavelength of 550 nm at 23°C. (3) Phase difference in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured with light of a wavelength of λ nm at 23°C. Rth(λ) is obtained by the formula: Rth = (nx - nz) × d, where d (nm) is the thickness of the layer (film). For example, "Rth(550)" is the phase difference in the thickness direction measured with light of a wavelength of 550 nm at 23°C. (4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Substantially orthogonal or parallel The expressions "substantially orthogonal" and "approximately orthogonal" include cases where the angle between the two directions is in the range of 90° ± 10°, preferably in the range of 90° ± 7°, and more preferably in the range of 90° ± 5°. The expressions “substantially parallel” and “approximately parallel” encompass cases where the angle between the two directions is in the range of 0° ± 10°, preferably in the range of 0° ± 7°, and more preferably in the range of 0° ± 5°. Furthermore, when “orthogonal” or “parallel” is used in this specification, it may include substantially orthogonal or substantially parallel conditions.

[0010] A. Figure 1 of the overall configuration of the polarizing plate with optical compensation layer is a schematic cross-sectional view of a polarizing plate with optical compensation layer according to one embodiment of the present invention. The polarizing plate with optical compensation layer 100 in the illustrated example comprises a polarizer 10, a first optical compensation layer 30, a second optical compensation layer 40, a third optical compensation layer 50, and a fourth optical compensation layer 60 in this order. In practice, as shown in the illustrated example, a protective layer 20 may be provided on the side of the polarizer 10 opposite to the first optical compensation layer 30. The polarizing plate with optical compensation layer may also have another protective layer (also called an inner protective layer) between the polarizer 10 and the first optical compensation layer 30. In the illustrated example, the inner protective layer is omitted. In this case, the first optical compensation layer 30 can also function as an inner protective layer. With such a configuration, further thinning of the polarizing plate with optical compensation layer can be achieved.

[0011] In embodiments of the present invention, the first optical compensation layer 30, the second optical compensation layer 40, the third optical compensation layer 50, and the fourth optical compensation layer 60 all exhibit refractive index characteristics of nx > nz > ny, and satisfy 1.10 < Re(450) / Re(550) ≤ 1.40. Therefore, in the polarizing plate with optical compensation layers according to embodiments of the present invention, the first optical compensation layer 30, the second optical compensation layer 40, the third optical compensation layer 50, and the fourth optical compensation layer 60 are all Z films and exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light. Furthermore, the Nz coefficient of the first optical compensation layer 30 is 0.10 or more and 0.40 or less or 0.65 or more and 0.85 or less, and the Nz coefficients of the second optical compensation layer 40, the third optical compensation layer 50, and the fourth optical compensation layer 60 are all 0.40 or more and 0.60 or less. In the polarizing plate with optical compensation layers according to an embodiment of the present invention, four optical compensation layers exhibiting refractive index characteristics nx > nz > ny are used, and specific wavelength dispersion characteristics and Nz coefficients are used, thereby preventing light leakage due to apparent axial misalignment of the polarizer's absorption axis when viewed from an oblique direction, while maintaining excellent anti-reflective properties due to excellent circular polarization function. Furthermore, when conventional circular polarizing plates are applied to image display devices (e.g., organic EL display devices), black displays may appear reddish. A reddish tint can excite or induce excitement, or evoke a sense of danger, and redness is an undesirable hue for black displays. In contrast, the polarizing plate with optical compensation layers according to an embodiment of the present invention can suppress visibility that would otherwise be noticeable due to redness by keeping oblique reflections in black displays low, and such oblique reflections in black displays may exhibit a bluish hue. As a result, redness in black displays can be suppressed. As described later, by forming the phase difference film using a liquid crystalline compound, a Z film exhibiting positive dispersion wavelength characteristics with Re(450) / Re(550) greater than 1.10 and 1.40 or less is particularly easily obtained. Therefore, by combining four Z films exhibiting positive dispersion wavelength characteristics with Re(450) / Re(550) greater than 1.10 and 1.40 or less, and each layer having a specific Nz coefficient, it is possible to achieve unprecedented and remarkable effects, such as suppressing oblique reflection in black display and suppressing redness in hue.

[0012] As described above, the first optical compensation layer 30, the second optical compensation layer 40, the third optical compensation layer 50, and the fourth optical compensation layer 60 each typically exhibit positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light (typically satisfying Re(450) > Re(550)). This configuration has the advantage that each optical compensation layer can be formed from the same material. Furthermore, since the four optical compensation layers exhibit the same wavelength dispersion characteristics, the material selection for each optical compensation layer becomes even easier.

[0013] The first optical compensation layer 30 has an in-plane phase difference Re(550) of preferably 190 nm to 310 nm, more preferably 200 nm to 300 nm. In one embodiment, the Nz coefficient of the first optical compensation layer is 0.10 or more and 0.40 or less, as described above, and preferably 0.20 or more and 0.30 or less. In this case, the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 are preferably substantially orthogonal. In another embodiment, the Nz coefficient of the first optical compensation layer is 0.65 or more and 0.85 or less, as described above, and preferably 0.70 or more and 0.80 or less. In this case, the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 are preferably substantially parallel.

[0014] In one embodiment, the second optical compensation layer 40 has an in-plane phase difference Re(550) preferably of 200 nm to 310 nm, more preferably of 210 nm to 300 nm. The Nz coefficient of the second optical compensation layer 40 is 0.40 or more and 0.60 or less, as described above. In this case, the angle between the slow axis of the second optical compensation layer 40 and the absorption axis of the polarizer 10 is preferably 80° to 110°.

[0015] In one embodiment, the third optical compensation layer 50 has an in-plane phase difference Re(550) preferably of 210 nm to 270 nm, more preferably of 220 nm to 260 nm. The Nz coefficient of the third optical compensation layer 50 is 0.40 or more and 0.60 or less, as described above. In this case, the angle between the slow axis of the third optical compensation layer 50 and the absorption axis of the polarizer 10 is preferably 100° to 130°.

[0016] In one embodiment, the fourth optical compensation layer 60 has an in-plane phase difference Re(550) preferably of 80 nm to 160 nm, more preferably of 90 nm to 150 nm. The Nz coefficient of the fourth optical compensation layer 60 is 0.40 or more and 0.60 or less, as described above. In this case, the angle between the slow axis of the fourth optical compensation layer 60 and the absorption axis of the polarizer 10 is preferably -20° to 25°.

[0017] In the embodiments of the present invention, the reflected hue (x,y) at azimuth angles (φ) of 30° and 210°, and at polar angles (Θ) = 42° and 49° at 150° and 330°, respectively, of the polarized plate with an optical compensation layer preferably satisfies 0 < x < 0.35 and 0 < y < 0.35, more preferably 0 < x < 0.32 and 0 < y < 0.32, and even more preferably 0 < x < 0.30 and 0 < y < 0.30. By having the reflected hue (x,y) within this range, a polarized plate with an optical compensation layer can be realized in which redness from oblique directions in black display is particularly suppressed. The reflected hue can be measured by irradiating light from the polarized plate side using a display measurement system (Konica Minolta, "DMS505").

[0018] The reflectance of the polarizing plate with an optical compensation layer according to the embodiment of the present invention is preferably 0.50% or less, more preferably 0.40% or less, and even more preferably 0.30% or less at azimuth angles (φ) of 30° and 210°, and at polar angles (Θ) of 150° and 330°, respectively. Having the reflectance within this range allows for maintaining low visibility from oblique directions in black displays (specifically, a state where the color is less noticeable), thus making the effects of the present invention more pronounced. The reflectance can be measured, similar to the reflected hue described above, by irradiating light from the polarizing plate side using a display measurement system (Konica Minolta, "DMS505"). Note that the reflectance according to this embodiment is a value calculated by dividing by the surface reflection.

[0019] In the lamination of each layer constituting the polarizing plate with optical compensation layer of the present invention, any suitable adhesive layer or bonding agent is used. Furthermore, for example, the fourth optical compensation layer 60 side of the polarizing plate with optical compensation layer 100 may have an adhesive layer (not shown) so that it can be attached to an image display panel. In this case, it is preferable that a release liner is temporarily attached to the surface of the adhesive layer until the polarizing plate with optical compensation layer is put into use. By temporarily attaching the release liner, the adhesive layer is protected and roll formation of the polarizing plate with optical compensation layer becomes possible.

[0020] A polarizing plate with an optical compensation layer may be elongated or sheet-shaped. In this specification, "elongated" means a slender shape in which the length is sufficiently longer than the width, and for example, includes a slender shape in which the length is 10 times or more, preferably 20 times or more, than the width. An elongated polarizing plate with an optical compensation layer can be wound into a roll. An elongated polarizing plate with an optical compensation layer can be manufactured, for example, by a so-called roll-to-roll process. Roll-to-roll is a method of continuously bonding elongated films together while conveying them on a roll and aligning their elongated directions. A sheet-shaped polarizing plate with an optical compensation layer may be manufactured by cutting an elongated polarizing plate with an optical compensation layer to a predetermined size (typically a size corresponding to an image display device), or by bonding together each component (each layer) that has been cut to a predetermined size.

[0021] The following describes in detail each layer that makes up the polarizing plate with an optical compensation layer.

[0022] A-1. Polarizer The polarizer 10 is typically composed 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.

[0023] The PVA resin preferably includes an acetoacetyl-modified PVA resin. With such a configuration, a polarizer with the desired mechanical strength can be obtained. The amount of acetoacetyl-modified PVA resin is preferably 5% to 20% by weight, and more preferably 8% to 12% by weight, when the total PVA resin is considered to be 100% by weight. A polarizer with even better mechanical strength can be obtained when the amount is within this range.

[0024] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as halide). Examples of iodide include potassium iodide, sodium iodide, and lithium iodide. The halide content in the polarizer is preferably 5 to 20 parts by weight, and more preferably 10 to 15 parts by weight, per 100 parts by weight of PVA resin. In the manufacturing method described later, the halide can be incorporated into the coating solution that forms the PVA resin layer, which is a precursor of the polarizer, and finally introduced into the polarizer. By introducing a halide into the polarizer, the orientation of PVA molecules in the polarizer can be increased, making it possible to realize a polarizer with excellent optical properties (typically, a combination of high polarization degree and high single-element transmittance).

[0025] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is preferably 41.0% to 46.0%, more preferably 42.0% to 45.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher. According to embodiments of the present invention, even if the transmittance of the polarizer is within the above range, the degree of polarization can be maintained within this range.

[0026] 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 thin phase difference film, it is possible to significantly reduce the thickness of the polarizing plate with an optical compensation layer. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be suppressed well, and good durability of the appearance during heating can be obtained.

[0027] Polarizers can be manufactured by any suitable method. For example, the resin film forming the polarizer may be a single layer of resin film or a laminate of two or more layers.

[0028] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with dichroic substances such as iodine or dichroic dyes and stretched, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA-based film with iodine and uniaxially stretching it are used because they have excellent optical properties.

[0029] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA-based film may be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be washed away, but the PVA-based film can also be swollen to prevent uneven dyeing.

[0030] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may further include, if necessary, air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, even when PVA is coated onto a thermoplastic resin, it is possible to increase the crystallinity of the PVA and achieve high optical properties. At the same time, by increasing the orientation of the PVA in advance, it is possible to prevent problems such as a decrease in the orientation of the PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, and to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps in which the laminate is immersed in a liquid, such as dyeing and water-based stretching, can be improved. Furthermore, by shrinking the laminate in the width direction through a drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such a polarizer manufacturing method are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0031] A-2. First Optical Compensation Layer The first optical compensation layer 30 is a Z film whose refractive index characteristics exhibit the relationship nx > nz > ny, as described above. The in-plane phase difference Re(550) of the first optical compensation layer is preferably 190 nm to 310 nm, more preferably 200 nm to 300 nm, and even more preferably 210 nm to 290 nm. If the in-plane phase difference of the first optical compensation layer is within this range, when the slow axis of the first optical compensation layer is substantially orthogonal or parallel to the absorption axis of the polarizer, the reduction in the oblique anti-reflection function caused by the apparent axial misalignment of the absorption axis of the polarizer can be further suppressed. In one embodiment, the Nz coefficient of the first optical compensation layer is typically 0.10 or more and 0.40 or less, preferably 0.20 or more and 0.30 or less, and more preferably 0.23 or more and 0.27 or less. If the Nz coefficient is within this range, then when the slow axis of the first optical compensation layer and the absorption axis of the polarizer are substantially orthogonal, better oblique anti-reflection characteristics can be achieved in combination with the effect of the in-plane phase difference described above. In another embodiment, the Nz coefficient of the first optical compensation layer is typically 0.65 or more and 0.85 or less, preferably 0.70 or more and 0.80 or less, and more preferably 0.73 or more and 0.77 or less. If the Nz coefficient is within this range, then the same effects as described above can be achieved when the slow axis of the first optical compensation layer and the absorption axis of the polarizer are substantially parallel.

[0032] As described above, the first optical compensation layer exhibits positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light, satisfying 1.10 < Re(450) / Re(550) ≤ 1.40. Furthermore, because the first optical compensation layer exhibits such wavelength dispersion characteristics, broadband operation is possible through a laminated configuration with other optical compensation layers. The Re(450) / Re(550) in the first optical compensation layer is preferably 1.11 or higher, more preferably 1.12 or higher, and even more preferably 1.13 or higher; the Re(450) / Re(550) is preferably 1.35 or lower, more preferably 1.30 or lower, even more preferably 1.20 or lower, and particularly preferably 1.15 or lower. When the above Re(450) / Re(550) is within this range, the reflectance in the oblique direction in black display can be kept low, and the redness in the oblique hue can be efficiently reduced. On the other hand, if Re(450) / Re(550) is 1.10 or less, the red hue in the diagonal direction in the black display may become stronger; if it exceeds 1.40, the reflectance in the diagonal direction in the black display may increase, making the redness of the hue more noticeable. Since the first optical compensation layer exhibits positive wavelength dispersion characteristics, it can satisfy Re(650) / Re(550) < 1. Re(650) / Re(550) is preferably 0.98 or less, more preferably 0.96 or less; Re(450) / Re(550) is preferably greater than 1.10, and more preferably 1.12 or more.

[0033] The first optical compensation layer may have any appropriate phase difference in the thickness direction. With respect to the wavelength dispersion characteristics in the thickness direction, the Rth(450) / Rth(550) of the first optical compensation layer preferably satisfies 1.00 ≤ Rth(450) / Rth(550) ≤ 1.40. The Rth(450) / Rth(550) of the first optical compensation layer is more preferably 1.00 or more, even more preferably 1.04 or more, particularly preferably 1.06 or more; more preferably 1.35 or less, even more preferably 1.30 or less, particularly preferably 1.20 or less, and most preferably 1.15 or less. When the above Rth(450) / Rth(550) is within this range, the reflectance in the oblique direction in black display can be kept lower, and the redness in the oblique hue can be reduced more efficiently.

[0034] The first optical compensation layer is typically a phase difference film (Z film) composed of any suitable material capable of achieving the above characteristics. Examples of materials for forming the phase difference film include liquid crystalline compounds and resins. The material for forming the phase difference film is preferably a liquid crystalline compound. In this specification, "compound" includes monomers and polymers. Therefore, liquid crystalline compounds include liquid crystalline monomers and liquid crystalline polymers. Polymers may also include low polymers (oligomers) with a molecular weight of 1000 or less and polymerization precursors (prepolymers). "Liquid crystalline" refers to a property that possesses both the fluidity of a liquid and the optical anisotropy of a crystal.

[0035] In one embodiment, the first optical compensation layer may preferably contain a liquid crystalline compound. The liquid crystalline compound can be any suitable compound exhibiting liquid crystalline properties. The liquid crystalline compound may preferably be polymerizable. That is, the liquid crystalline compound may preferably be a polymerizable liquid crystalline compound. A "polymerizable liquid crystalline compound" refers to a compound that has polymerizable groups and is liquid crystalline. A polymerizable group refers to a group that participates in the polymerization reaction, and includes photopolymerizable groups and thermally polymerizable groups. The polymerizable group is preferably a photopolymerizable group. Here, a photopolymerizable group refers to a group that can participate in the polymerization reaction by active radicals or acids generated from a photopolymerization initiator. If the liquid crystalline compound is polymerizable, the orientation of the molecules of the liquid crystalline compound can be fixed by oriented the molecules before polymerization. Since the orientation of the liquid crystalline layer thus formed (sometimes referred to as a liquid crystalline orientation solidification layer) is fixed by the polymerization reaction, the polymer in the liquid crystalline layer may be non-liquid crystalline. Therefore, the formed liquid crystal layer does not undergo transitions between the liquid crystal phase, glass phase, and crystalline phase due to temperature changes, which are characteristic of liquid crystal compounds. As a result, the liquid crystal layer can become an extremely stable phase difference film that is unaffected by temperature changes.

[0036] In one embodiment, the liquid crystalline compound may preferably be a photo-oriented compound (hereinafter also referred to as a photo-oriented compound). In this specification, "photo-oriented" means the property of exhibiting anisotropy upon light irradiation. If the liquid crystalline compound is a photo-oriented compound, orientation can be imparted to the phase difference film formed from the liquid crystalline compound by irradiation with light. Examples of light include ultraviolet light, visible light, and infrared light. These lights may be polarized. The irradiated light is preferably polarized ultraviolet light. If the liquid crystalline compound is a photo-oriented compound, a phase difference film exhibiting optical anisotropy can be produced without using a film such as a rubbing film to orient the liquid crystalline compound. Furthermore, by using a photo-oriented compound, it is easier to form a Z film in which the refractive index nz in the thickness direction is oriented to be relatively larger than the refractive index ny in the phase-advancing axis direction. As a result, it is easier to adjust the Nz coefficient of the Z film to a desired range. The Nz coefficient and in-plane phase difference can be adjusted by appropriately adjusting the drying conditions, film thickness, heating conditions, etc., of the phase difference film. By using the above-mentioned liquid crystalline compound, it is possible to realize a Z film that has a desired in-plane phase difference, exhibits the predetermined wavelength dispersion characteristics (1.10 < Re(450) / Re(550) ≤ 1.40), and has a very thin thickness.

[0037] Photo-orienting compounds have a molecular skeleton that exhibits photo-orienting properties. A photo-orienting molecular skeleton refers to a molecular structure that exhibits anisotropy through photoreaction upon light irradiation. Therefore, by having a photo-orienting molecular skeleton, photo-orienting compounds can undergo photodimerization and / or photoisomerization reactions. Photoisomerization reactions may include, for example, cis-trans isomerization reactions. Examples of photo-orienting compounds include compounds having any suitable photo-orienting molecular skeleton. Examples of photo-orienting molecular skeletons include cinnamoyl skeletons, azobenzene skeletons, coumarin skeletons, chalcone skeletons, stilbene skeletons, biphenylacryloyl skeletons, furylacryloyl skeletons, naphthylacryloyl skeletons, anthracene skeletons, and quinoline skeletons. In these molecular skeletons, at least one hydrogen atom on the aromatic ring and / or on the carbon that does not participate in the photoreaction of the spacer may be substituted with a substituent other than hydrogen. Substituents can be any group that does not interfere with photodimerization and photoisomerization reactions, such as alkyl groups, aryl groups, cycloalkyl groups, alkoxy groups, hydroxyl groups, halogen atoms, trifluoromethyl groups, and cyano groups. The photo-orienting compound may further have molecular skeletons other than those mentioned above. For example, the photo-orienting compound may further have a mesogenic skeleton such as a biphenyl skeleton, a terphenyl skeleton, or a phenylbenzoate skeleton.

[0038] The photo-orienting compound may preferably be at least one compound from among cinnamic acid, cinnamic acid derivatives, azobenzene, azobenzene derivatives, coumarin, coumarin derivatives, chalcone, chalcone derivatives, stilbene, and stilbene derivatives. Similar to the photo-orienting molecular skeleton described above, the aromatic ring in these photo-orienting compounds may have at least one hydrogen atom on the carbon that does not participate in the photoreaction on the aromatic ring and / or spacer substituted with a substituent other than hydrogen. The substituent should not interfere with the photodimerization and photoisomerization reactions, and examples include alkyl groups, aryl groups, cycloalkyl groups, alkoxy groups, hydroxyl groups, halogen atoms, trifluoromethyl groups, cyano groups, etc. Examples of cinnamic acid derivatives include ester derivatives obtained by the reaction of the carboxyl group of cinnamic acid with any suitable alcohol. Examples of cinnamic acid derivatives include cinnamic acid esters such as methyl cinnamate, ethyl cinnamate, propyl cinnamate, and n-butyl cinnamate. Details of such photo-oriented compounds are described, for example, in Japanese Patent Publication No. 2015-152745, Japanese Patent Publication No. 2016-4142, International Publication No. 2013-81066, and International Publication No. 2024-38887. The descriptions in said publications are incorporated herein by reference.

[0039] The material used to form the above-mentioned phase difference film may preferably be a liquid crystalline compound alone or in combination with other liquid crystalline compounds. The material used to form the phase difference film may also contain any suitable components other than the liquid crystalline compound. Therefore, the material used to form the phase difference film may consist of a composition containing a liquid crystalline compound and components other than the liquid crystalline compound. Examples of components other than the liquid crystalline compound include polymerizable compounds, polymerization initiators, crosslinking agents, solvents, and additives. The proportions of each component can be set in appropriate proportions depending on the purpose. Details of such components other than the liquid crystalline compound are described, for example, in Japanese Patent Publication No. 2015-152745 and Japanese Patent Publication No. 2016-4142. The descriptions in these publications may be incorporated herein by reference.

[0040] The birefringence Δn (nx−ny) of the retardation film is preferably 0.030 or more, more preferably 0.040 or more, and still more preferably 0.045 or more. The upper limit of the birefringence Δn can be, for example, 0.100. Having such a large birefringence Δn enables realization of a Z-film having a desired in-plane retardation with a smaller thickness. Therefore, further thickness reduction of the Z-film can be achieved. As a result, the present invention can contribute to further thickness reduction of a polarizing plate with an optical compensation layer to which the Z-film is applied.

[0041] An example of a method for producing a retardation film using a liquid crystalline compound is described below. In one embodiment, a liquid crystalline polymer may be used as the liquid crystalline compound. The liquid crystalline polymer that can be used in the production method of the present embodiment has photoalignment properties. Specifically, first, a liquid crystalline polymer is prepared. The liquid crystalline polymer may be, for example, a compound obtained by polymerizing one or two or more of the above liquid crystalline compounds. Next, a liquid crystalline polymer solution is prepared by dissolving the obtained liquid crystalline polymer in any appropriate solvent. The concentration of the liquid crystalline polymer solution can be adjusted to any appropriate concentration. Regarding the concentration of the liquid crystalline polymer solution, the amount of the liquid crystalline compound relative to the total amount of the liquid crystalline polymer solution is preferably 7% by weight or more, more preferably 10% by weight or more, and still more preferably 12% by weight or more. The upper limit of the liquid crystalline compound can be, for example, 50% by weight.

[0042] Any suitable solvent can be used as the solvent, as long as it does not impair the coating properties. By appropriately selecting the solvent, a Z film with the desired Nz coefficient can be prepared more easily. Examples of solvents include cyclopentanone, cyclohexanone, cyclohexanol, cyclopentanol, ethyl carbitol, N-methyl-2-pyrrolidone, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, hexylene glycol, propylene glycol, propylene glycol monoacetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether, dioxane, dichloroethane, toluene, o-dichlorobenzene, butyl butyrate, butyl ether, methyl cellosolve, ethyl cellosolve, diisobutyl ketone, methylcyclohexene, 3-methoxy-N,N-dimethylpropanamide, tetrahydrofurfuryl acetate, and amyl acetate. These solvents can be used individually or in combination of two or more. Furthermore, even if the solvent is difficult to dissolve the above-mentioned liquid crystalline polymer, it may be mixed with the above-mentioned organic solvent and used, as long as the resulting polymer does not precipitate.

[0043] Next, the prepared liquid crystalline compound solution is applied to any suitable support substrate to form a coating film (wet coating film). As the support substrate, for example, a glass substrate or any suitable polymer film can be used. Examples of polymer films include polyethylene terephthalate film, cellulosic films such as diacetylcellulose and triacetylcellulose, polycarbonate films such as bisphenol A carbonate copolymer, linear or branched polyolefin films such as polyethylene, polypropylene and ethylene-propylene copolymer, cyclic polyolefin films, polyamide films, imide films, and sulfone films. Any suitable method can be used to form the coating film. Examples of coating film formation methods include bar coating, spin coating, flow coating, roll coating, inkjet, and printing.

[0044] If necessary, the wet coating film is dried. Drying can be performed at an appropriate temperature at which the solvent can evaporate. The drying temperature can be, for example, 30°C to 200°C, preferably 40°C to 150°C, and more preferably 50°C to 120°C. A coating film of the liquid crystalline polymer (dry coating film) can be obtained by drying. The Nz coefficient of the Z-film can be adjusted by appropriately adjusting the drying temperature. For example, increasing the drying temperature decreases the Nz coefficient; lowering the drying temperature can increase the Nz coefficient.

[0045] Next, the coating film of the above liquid crystalline polymer is irradiated with polarized ultraviolet light. When the coating film of the liquid crystalline polymer is irradiated with polarized ultraviolet light, molecules of the liquid crystalline polymer can be induced to align in a predetermined direction. The polarized ultraviolet light can be, for example, polarized light converted by ultraviolet light emitted from a light source passing through a polarizing plate. Examples of the light source include metal halide lamps, high-pressure mercury lamps, and low-pressure mercury lamps. As the wavelength of the ultraviolet light, an appropriate wavelength can be selected according to the type of the liquid crystalline compound, the composition of the material, and the like. The wavelength can be selected, for example, within the range of 100 nm to 400 nm. Ultraviolet irradiation can be performed through any appropriate filter. As the filter, for example, a band-pass filter that transmits only light in a predetermined wavelength range can be used. Any appropriate irradiation dose can be adopted for the irradiation dose of polarized ultraviolet light according to the type of liquid crystalline compound constituting the coating film, the composition of the material, the dimensions of the coating film, and the like. The irradiation dose (integrated light amount) of polarized ultraviolet light is, for example, 50 J / cm ２ to 10000 J / cm ２ , preferably 100 J / cm ２ to 3000 J / cm ２ , more preferably 400 J / cm ２ to 1600 J / cm ２ .

[0046] In the above manufacturing method, preferably, the coating film is heated after being irradiated with polarized ultraviolet light. By heating, the orientation of the coating film in a predetermined direction (e.g., the thickness direction) is promoted, and the oriented molecules can be fixed. In embodiments of the present invention, a Z film can be obtained as a result of promoting the orientation of the liquid crystalline compound so that it can exhibit refractive index characteristics of nx > nz > ny. Heating can be carried out by any suitable heating means and method. The heating conditions can be appropriately set according to the temperature at which the liquid crystalline properties of the coating film can be exhibited. The temperature at which liquid crystalline properties can be exhibited is above the temperature at which the liquid crystalline compound undergoes a phase transition from the solid phase to the liquid crystalline phase, and below the temperature at which it undergoes a phase transition from the liquid crystalline phase to the isotropic phase. Specifically, the heating temperature may be, for example, 70°C to 160°C, preferably 90°C to 150°C, and more preferably 110°C to 140°C. The heating time may be, for example, 1 minute to 30 minutes, preferably 3 minutes to 20 minutes, and more preferably 5 minutes to 10 minutes. Details of such phase difference films are described, for example, in International Publication No. 2024-38887. The description in said publication may be incorporated herein by reference.

[0047] The method for obtaining the first optical compensation layer according to the embodiments of the present invention is not limited to the above, and the first optical compensation layer can be manufactured by any suitable method as long as it does not hinder the objective of the present invention. The first optical compensation layer may be manufactured, for example, by the method described in Japanese Patent Application Publication No. 2015-152745 and Japanese Patent Application Publication No. 2016-4142.

[0048] The thickness of the first optical compensation layer is preferably 0.1 μm or more and less than 10 μm, more preferably 1 μm or more and 8 μm or less, and even more preferably 3 μm or more and 5 μm or less. In one embodiment of the present invention, by forming a Z film using a liquid crystalline compound, an optical compensation layer having a desired in-plane phase difference can be obtained with a thinner thickness than conventional methods. As a result, the overall thinning of the polarizing plate with the optical compensation layer can be significantly improved.

[0049] A-3. Second Optical Compensation Layer The second optical compensation layer 40 may be a Z film whose refractive index characteristics exhibit the relationship nx > nz > ny, as described above. The in-plane phase difference Re(550) of the second optical compensation layer is preferably 200 nm to 310 nm, more preferably 210 nm to 300 nm, and even more preferably 210 nm to 270 nm. In one embodiment, if the in-plane phase difference of the second optical compensation layer is within this range, for example, by setting the angle between the slow axis of the second optical compensation layer and the absorption axis of the polarizer to 85° to 100°, it is possible to neutralize the reflected hue even when using a material exhibiting positive wavelength dispersion characteristics. Therefore, by doing so, it is possible to further prevent a decrease in the oblique anti-reflection function caused by the apparent misalignment of the absorption axis of the excellent polarizer.

[0050] The Nz coefficient of the second optical compensation layer is typically 0.40 to 0.60, preferably 0.42 to 0.58, more preferably 0.45 to 0.55, and even more preferably 0.48 to 0.52. The Nz coefficient of the second optical compensation layer may be, for example, 0.5. If the Nz coefficient is within this range, by setting the angle between the slow axis of the second optical compensation layer and the absorption axis of the polarizer to 80° to 110°, better oblique anti-reflection characteristics can be achieved.

[0051] As described above, the second optical compensation layer exhibits positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light, and in particular satisfies 1.10 < Re(450) / Re(550) ≤ 1.40. Furthermore, because the second optical compensation layer exhibits such wavelength dispersion characteristics, broadband operation is possible by lamination configuration with other optical compensation layers. The Re(450) / Re(550) of the second optical compensation layer is preferably 1.11 or higher, more preferably 1.12 or higher, and even more preferably 1.13 or higher; Re(450) / Re(550) is preferably 1.35 or lower, more preferably 1.30 or lower, even more preferably 1.20 or lower, and particularly preferably 1.15 or lower. When the wavelength dispersion characteristic Re(450) / Re(550) is within this range, the reflectance in the oblique direction in black display can be kept low, and the redness in the oblique hue can be efficiently reduced. On the other hand, if Re(450) / Re(550) is 1.10 or less, the red hue in the diagonal direction in the black display may become stronger; if it exceeds 1.40, the reflectance in the diagonal direction in the black display may increase, making the reddish hue more noticeable. The second optical compensation layer exhibits positive wavelength dispersion characteristics, so it can satisfy Re(650) / Re(550) < 1. Re(650) / Re(550) is preferably 0.98 or less, more preferably 0.96 or less; Re(450) / Re(550) is preferably greater than 1.10, and more preferably 1.12 or more.

[0052] The second optical compensation layer may have any appropriate phase difference in the thickness direction. With respect to the wavelength dispersion characteristics in the thickness direction, the Rth(450) / Rth(550) of the second optical compensation layer preferably satisfies 1.00 ≤ Rth(450) / Rth(550) ≤ 1.40. The Rth(450) / Rth(550) of the second optical compensation layer is more preferably 1.00 or higher, even more preferably 1.05 or higher, particularly preferably 1.09 or higher; more preferably 1.35 or lower, even more preferably 1.30 or lower, particularly preferably 1.20 or lower, and most preferably 1.15 or lower. When the wavelength dispersion characteristic Rth(450) / Rth(550) in the thickness direction is within this range, the reflectance in the oblique direction in black display can be further reduced, and the redness in the oblique hue can be further reduced more efficiently.

[0053] The angle between the slow axis of the second optical compensation layer 40 and the absorption axis of the polarizer 10 is preferably 80° to 110°, more preferably 85° to 107°, even more preferably 90° to 105°, and particularly preferably 95° to 104°. By setting this angle within this range, a synergistic effect with the in-plane phase difference and Nz coefficient of the second optical compensation layer can be achieved to obtain superior oblique anti-reflection characteristics.

[0054] The thickness of the second optical compensation layer is preferably 0.1 μm or more and less than 10 μm, more preferably 1 μm or more and 8 μm or less, and even more preferably 3 μm or more and 5 μm or less. In one embodiment of the present invention, by forming a Z film using a liquid crystalline compound, an optical compensation layer having a desired in-plane phase difference can be obtained with a thinner thickness than conventional methods. As a result, the overall thinning of the polarizing plate with the optical compensation layer can be significantly improved.

[0055] Regarding the material and method for forming the second optical compensation layer, the material and method for forming the phase difference film (Z film) described in Section A-2 above can be used with respect to the first optical compensation layer, insofar as the above characteristics can be achieved.

[0056] A-4. Third Optical Compensation Layer The third optical compensation layer 50 may be a Z film whose refractive index characteristics exhibit the relationship nx > nz > ny, as described above. The in-plane phase difference Re(550) of the third optical compensation layer is preferably 210 nm to 270 nm, and more preferably 220 nm to 260 nm.

[0057] The Nz coefficient of the third optical compensation layer is typically 0.40 to 0.60, preferably 0.42 to 0.58, more preferably 0.45 to 0.55, and even more preferably 0.48 to 0.52. The Nz coefficient of the third optical compensation layer may be, for example, 0.5. If the Nz coefficient is within this range, by setting the angle between the slow axis of the third optical compensation layer and the absorption axis of the polarizer to 100° to 130°, better oblique anti-reflection characteristics can be achieved.

[0058] As described above, the third optical compensation layer exhibits positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light, and in particular satisfies 1.10 < Re(450) / Re(550) ≤ 1.40. Furthermore, because the third optical compensation layer exhibits such wavelength dispersion characteristics, broadband operation is possible by lamination configuration with other optical compensation layers. The Re(450) / Re(550) of the third optical compensation layer is preferably 1.11 or higher, more preferably 1.12 or higher, and even more preferably 1.13 or higher; Re(450) / Re(550) is preferably 1.35 or lower, more preferably 1.30 or lower, even more preferably 1.20 or lower, and particularly preferably 1.15 or lower. When the wavelength dispersion characteristic Re(450) / Re(550) is within this range, the reflectance in the oblique direction in black display can be kept low, and the redness in the oblique hue can be efficiently reduced. On the other hand, if Re(450) / Re(550) is 1.10 or less, the red hue in the diagonal direction in the black display may become stronger; if it exceeds 1.40, the reflectance in the diagonal direction in the black display may increase, making the reddish hue more noticeable. Since the third optical compensation layer exhibits positive wavelength dispersion characteristics, it can satisfy Re(650) / Re(550) < 1. Re(650) / Re(550) is preferably 0.98 or less, more preferably 0.96 or less; Re(450) / Re(550) is preferably greater than 1.10, and more preferably 1.12 or more.

[0059] The third optical compensation layer may have any appropriate phase difference in the thickness direction. With respect to the wavelength dispersion characteristics in the thickness direction, the Rth(450) / Rth(550) of the third optical compensation layer preferably satisfies 1.00 ≤ Rth(450) / Rth(550) ≤ 1.40. The Rth(450) / Rth(550) of the third optical compensation layer is more preferably 1.00 or higher, even more preferably 1.05 or higher, particularly preferably 1.09 or higher; more preferably 1.35 or lower, even more preferably 1.30 or lower, particularly preferably 1.20 or lower, and most preferably 1.15 or lower. When the above Rth(450) / Rth(550) is within this range, the reflectance in the oblique direction in black display can be further reduced, and the redness in the oblique hue can be further reduced more efficiently.

[0060] The angle between the slow axis of the third optical compensation layer 50 and the absorption axis of the polarizer 10 is preferably 100° to 130°, and more preferably 110° to 130°. By setting this angle within this range, a synergistic effect with the in-plane phase difference and Nz coefficient of the third optical compensation layer can be achieved, resulting in superior oblique anti-reflection characteristics.

[0061] The thickness of the third optical compensation layer is preferably 0.1 μm or more and less than 10 μm, more preferably 1 μm or more and 8 μm or less, and even more preferably 3 μm or more and 5 μm or less. In one embodiment of the present invention, by forming a Z film using a liquid crystalline compound, an optical compensation layer having a desired in-plane phase difference can be obtained with a thinner thickness than conventional methods. As a result, the overall thinning of the polarizing plate with the optical compensation layer can be significantly improved.

[0062] Regarding the material and method for forming the third optical compensation layer, the material and method for forming the phase difference film (Z film) described in Section A-2 above can be used with respect to the first optical compensation layer, insofar as the above characteristics can be achieved.

[0063] A-5. The fourth optical compensation layer The fourth optical compensation layer 60 may be a Z film whose refractive index characteristics are in the relationship nx > nz > ny, as described above. The in-plane phase difference Re(550) of the fourth optical compensation layer is preferably 80 nm to 160 nm, more preferably 90 nm to 150 nm, even more preferably 100 nm to 145 nm, and particularly preferably 110 nm to 130 nm. In one embodiment, if the in-plane phase difference of the fourth optical compensation layer is within this range, it may be possible to neutralize the reflected hue even when using a material exhibiting positive wavelength dispersion characteristics.

[0064] The Nz coefficient of the fourth optical compensation layer is typically 0.40 to 0.60, preferably 0.42 to 0.58, more preferably 0.45 to 0.55, and even more preferably 0.48 to 0.52. The Nz coefficient of the fourth optical compensation layer may be, for example, 0.5. If the Nz coefficient is within this range, better oblique anti-reflection characteristics can be achieved by setting the angle between the slow axis of the fourth optical compensation layer and the absorption axis of the polarizer to -20° to 25°.

[0065] As described above, the fourth optical compensation layer exhibits positive wavelength dispersion characteristics in which the phase difference value decreases with respect to the wavelength of the measured light, and in particular satisfies 1.10 < Re(450) / Re(550) ≤ 1.40. Furthermore, because the fourth optical compensation layer exhibits such wavelength dispersion characteristics, broadband performance can be achieved by laminating it with other optical compensation layers. The Re(450) / Re(550) of the fourth optical compensation layer is preferably 1.11 or higher, more preferably 1.12 or higher, and even more preferably 1.13 or higher; Re(450) / Re(550) is preferably 1.35 or lower, more preferably 1.30 or lower, even more preferably 1.20 or lower, and particularly preferably 1.15 or lower. When the wavelength dispersion characteristic Re(450) / Re(550) is within this range, the reflectance in the oblique direction in black display can be kept low, and the redness in the oblique hue can be efficiently reduced. On the other hand, if Re(450) / Re(550) is 1.10 or less, the red hue in the diagonal direction in the black display may become stronger; if it exceeds 1.40, the reflectance in the diagonal direction in the black display may increase, making the redness of the hue more noticeable. Since the fourth optical compensation layer exhibits positive wavelength dispersion characteristics, it can satisfy Re(650) / Re(550) < 1. Re(650) / Re(550) is preferably 0.98 or less, more preferably 0.96 or less; Re(450) / Re(550) is preferably greater than 1.10, and more preferably 1.12 or more.

[0066] The fourth optical compensation layer may have any appropriate phase difference in the thickness direction. With respect to the wavelength dispersion characteristics in the thickness direction, the Rth(450) / Rth(550) of the fourth optical compensation layer preferably satisfies 1.00 ≤ Rth(450) / Rth(550) ≤ 1.40. The Rth(450) / Rth(550) of the fourth optical compensation layer is more preferably 1.00 or higher, even more preferably 1.05 or higher, particularly preferably 1.09 or higher; more preferably 1.35 or lower, even more preferably 1.30 or lower, particularly preferably 1.20 or lower, and most preferably 1.15 or lower. When the wavelength dispersion characteristic Rth(450) / Rth(550) in the thickness direction is within this range, the reflectance in the oblique direction in black display can be further reduced, and the redness in the oblique hue can be further reduced more efficiently.

[0067] The angle between the slow axis of the fourth optical compensation layer 60 and the absorption axis of the polarizer 10 is preferably -20° to 25°, more preferably -10° to 15°, even more preferably 0° to 10°, and particularly preferably 5° to 9°. By setting this angle within this range, a synergistic effect with the in-plane phase difference and Nz coefficient of the fourth optical compensation layer can be achieved to obtain superior oblique anti-reflective properties.

[0068] The thickness of the fourth optical compensation layer is preferably 0.1 μm or more and less than 10 μm, more preferably 1 μm or more and less than 8 μm, even more preferably 1 μm or more and 5 μm or less, and particularly preferably 1 μm or more and 3 μm or less. In one embodiment of the present invention, by forming a Z film using a liquid crystalline compound, an optical compensation layer having a desired in-plane phase difference can be obtained with a thinner thickness than conventional methods. As a result, the overall thinning of the polarizing plate with the optical compensation layer can be significantly improved.

[0069] Regarding the material and method for forming the fourth optical compensation layer, insofar as the above characteristics can be achieved, the material and method for forming the phase difference film (Z film) described in Section A-2 above can be used with respect to the first optical compensation layer.

[0070] A-6. Protective Layer The protective layer 20 is composed of any suitable resin film. Typical materials for the resin film include cellulosic resins such as triacetylcellulose (TAC), cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. Typical examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. From the viewpoint of ease of shaping, cellulose resins are preferred, and TAC is more preferred. From the viewpoint of obtaining polarizing plates with low moisture permeability and excellent durability, cycloolefin resins and (meth)acrylic resins are preferred.

[0071] The polarizing plate with an optical compensation layer is typically placed on the viewing side of an image display device (e.g., an organic EL display device), and the protective layer 20 is typically placed on the viewing side. Therefore, the protective layer 20 may be surface-treated as needed. Examples of surface treatments include hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating. Furthermore, the protective layer 20 may be treated as needed to improve visibility when viewed through polarized sunglasses (typically by providing (elliptic) polarization function or providing ultra-high phase difference). By applying such treatment, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with an optical compensation layer can be suitably applied to image display devices that may be used outdoors.

[0072] When an inner protective layer (not shown) is provided between the polarizer 10 and the first optical compensation layer 30, in one embodiment, the inner protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0073] The thickness of the protective layer 20 and the inner protective layer (if present) is preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm, respectively. If the protective layer 20 is surface-treated, the thickness of the protective layer 20 includes the thickness of the surface treatment layer.

[0074] B. Method for Manufacturing Polarizing Plates with Optical Compensation Layers Polarizing plates with optical compensation layers according to embodiments of the present invention can be manufactured by any suitable method. For example, a polarizing plate with optical compensation layers can be manufactured by sequentially laminating a polarizer (polarizing plate including a polarizer), a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer as described in Section A above. In one embodiment, a polarizing plate with optical compensation layers is preferably manufactured by laminating a polarizer, a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer using a roll-to-roll method. During the lamination, the layers (such as substrates) temporarily attached to the polarizer and each optical compensation layer are peeled off at any suitable time. The lamination can be carried out via any suitable adhesive layer (tack layer or adhesive layer) between each layer. In one embodiment, the order of lamination is not restricted as long as the polarizer with optical compensation layers is configured to include a polarizer, a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer in that order. For example, a laminate may be obtained by laminating the first optical compensation layer and the second optical compensation layer by roll-to-roll, the first optical compensation layer of the laminate may be laminated onto the polarizer surface, then the third optical compensation layer may be laminated onto the surface of the second optical compensation layer by roll-to-roll, and then the fourth optical compensation layer may be laminated onto the surface of the third optical compensation layer by roll-to-roll; or a laminate may be obtained by laminating the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical laminate in this order, and then the first optical compensation layer of the laminate may be laminated onto the polarizer surface by roll-to-roll. By doing so, a polarizer with optical compensation layers according to an embodiment of the present invention can be obtained.

[0075] In another example of the method for manufacturing a polarizing plate with an optical compensation layer according to an embodiment of the present invention, the polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer may be cut to a predetermined size, and the cut layers may be laminated together in the order of polarizer, first optical compensation layer, second optical compensation layer, third optical compensation layer, and fourth optical compensation layer. By doing so, a polarizing plate with an optical compensation layer according to an embodiment of the present invention can also be obtained.

[0076] C. Image Display Device The polarizing plates with optical compensation layers described in sections A and B above can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such polarizing plates with optical compensation layers. An image display device according to an embodiment of the present invention typically includes a polarizing plate with optical compensation layers described in sections A and B above on its viewing side. Typical examples of image display devices include liquid crystal displays and organic EL displays. As described above, the polarizing plates with optical compensation layers according to embodiments of the present invention can suppress reflection in oblique directions and suppress the redness of hues in oblique directions, so they can be suitably used in organic EL displays having a highly reflective metal layer. Therefore, the image display device is preferably an organic EL display device.

[0077] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows.

[0078] (1) Thickness: For thicknesses of 10 μm or less, an interferometer (MCPD9800 manufactured by Otsuka Electronics Co., Ltd.) was used for measurement; for thicknesses exceeding 10 μm, a digital micrometer was used. (2) Phase difference: 50 mm x 50 mm samples were cut from each optical compensation layer and used as measurement samples, and measured using an AxoScan manufactured by Axometrics Inc. The measurement wavelengths were 450 nm and 550 nm, and the measurement temperature was 23°C. In addition, the average refractive index was measured using a prism coupler manufactured by Metricon Inc., and the refractive indices nx, ny, and nz were calculated from the obtained phase difference values. The Nz coefficient was calculated from the phase difference values ​​and the above thickness. (3) Visual color: The obtained polarizing plates with optical compensation layers were visually inspected from oblique directions (polar angles of 42° and 49°), and the color in black display was observed. Based on the observation results, if it had a bluish tint, it was evaluated as "blue," and if it had a reddish tint, it was evaluated as "red." (4) Reflectance characteristics in oblique directions (reflection hue and reflectance) Using a display measurement system (Konica Minolta, "DMS505"), light was irradiated from the polarizer side of the evaluation panel, and the reflection hue (x, y) and reflectance were measured for polar angles of 42° and 49° at azimuth angles of 30° and 210°, and at 150° and 330°. The reflectance was calculated by dividing it by the surface reflection (reflection of the outermost HC layer). The obtained reflection hue and reflectance were evaluated according to the following criteria.・Reflectance Hue (x, y) A (Excellent): x ≤ 0.30 and y ≤ 0.30 B (Good): x ≤ 0.30 and 0.30 < y ≤ 0.37 C (Acceptable): 0.30 ≤ x ≤ 0.35 and y ≤ 0.37 D (Unacceptable): The highest value at θ in any of the φ is 0.35 ≤ x and y ≤ 0.30 E (Poor): The highest value at θ in any of the φ is 0.35 ≤ x and 0.30 ≤ y ・Reflectance Y% A (Excellent): Y ≤ 0.15 B (Good): 0.15 < Y < 25 C (Acceptable): 0.25 ≤ Y ≤ 0.35 D (Unacceptable): 0.35 < Y < 0.5 E (Poor): The highest value at θ in any of the φ is 0.50 ≤ Y

[0079] [Fabrication of Polarizing Plates] (Manufacturing Example Pol-1: Fabrication of Polarizing Plates) An amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) with a long length and a Tg of approximately 75°C was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to corona treatment. 100 parts by weight of a PVA-based resin, which was a mixture of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, was mixed with 13 parts by weight of potassium iodide, and this mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). 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-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, it was immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (a iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizer obtained would be the desired value (staining treatment). Next, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was uniaxially stretched between rolls with different peripheral speeds while immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, so that the total stretching ratio in the longitudinal direction was 5.5 times (water stretching treatment). After that, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). After that, while drying in an oven maintained at approximately 90°C, it was brought into contact with a heated roll made of stainless steel with a surface temperature maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizer configuration was obtained. The transmittance Ts of the polarizer alone was 43.3%.An HC-COP film was bonded to the surface of the obtained polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive. The HC-COP film is a cycloolefin resin (COP) film (25 μm thick) with an HC layer (4 μm thick) formed on it, and it was bonded so that the COP film was on the polarizer side. The COP film had a Re(550) of 135 nm. Next, the resin substrate was peeled off, and a triacetylcellulose (TAC) film (25 μm thick) was bonded to the peeled surface via an ultraviolet-curing adhesive. In this way, a long polarizing plate Pol-1 having the structure of HC layer / COP film (protective layer) / polarizer / TAC film (protective layer) was obtained.

[0080] [Preparation of Phase Difference Films] <Synthesis of Liquid Crystalline Compounds (Liquid Crystalline Polymers)> The abbreviations for the components and solvents used in the synthesis of the following liquid crystalline polymers are as follows: (Photo-Oriented Monomer Compounds) (Polymerization initiator) AIBN: 2,2'-azobisisobutyronitrile (Solvent, etc.) NMP: N-methyl-2-pyrrolidone CPN: Cyclopentanone HG: Hexylene glycol EC: Ethyl carbitol cHexOH: Cyclohexanol THF: Tetrahydrofuran AcAm: Amyl acetate PGMEA: Propylene glycol monomethyl ether acetate F563: Megafac F-563 (Surfactant manufactured by DIC Corporation)

[0081] (Synthesis Example P-1: Synthesis of Liquid Crystalline Polymer P-1) In a reaction vessel equipped with a stirring device, a monomer mixture was prepared by dissolving the photo-oriented monomer compound shown in formula (1-1) (2.49 g, 7.50 mmol), the photo-oriented monomer compound shown in formula (1-2) (9.96 g, 32.5 mmol), the photo-oriented monomer compound shown in formula (1-4) (4.40 g, 10.0 mmol), and AIBN (0.821 g, 5.00 mmol) in NMP (24.8 g) and dissolving them in AIBN (0.821 g, 5.00 mmol). NMP (16.5 g) was placed in another reaction vessel equipped with a stirring device, heated to 60°C, and then the monomer mixture was added dropwise over 2 hours under a nitrogen atmosphere at 60°C to obtain a reaction solution. The reaction solution was stirred for 12 hours while maintaining its temperature at 60°C. After 12 hours, the reaction solution was poured into a methanol / pure water mixed solvent to precipitate the polymer (liquid crystalline polymer). After filtering off the precipitated liquid crystalline polymer, it was washed with methanol to obtain powdered liquid crystalline polymer P-1.

[0082] (Synthesis Example P-2: Synthesis of Liquid Crystalline Polymer P-2) In a reaction vessel equipped with a stirring device, a monomer mixture solution was prepared by dissolving the photo-oriented monomer compound shown in formula (1-1) (6.48 g, 19.5 mmol), the photo-oriented monomer compound shown in formula (1-2) (27.9 g, 91.0 mmol), the photo-oriented monomer compound shown in formula (1-3) (5.70 g, 19.5 mmol), and AIBN (1.07 g, 6.50 mmol) in NMP (98.7 g) and dissolving them in AIBN (1.07 g, 6.50 mmol). In another reaction vessel equipped with a stirring device, NMP (65.8 g) was placed and heated to 60°C. After heating, the monomer mixture solution was added dropwise over 2 hours at 60°C under a nitrogen atmosphere to obtain a reaction solution. The reaction solution temperature was maintained at 60°C and stirred for 12 hours. After 12 hours, the reaction solution was poured into a methanol / pure water mixed solvent to precipitate the polymer (liquid crystalline polymer). After filtering off the precipitated liquid crystalline polymer, it was washed with methanol to obtain powdered liquid crystalline polymer P-2.

[0083] (Synthesis Example P-3: Synthesis of Liquid Crystalline Polymer Material P-3) In a reaction vessel equipped with a stirring device, a monomer mixture solution was prepared by dissolving the photo-orienting compound shown in formula (1-1) (9.97 g, 30.0 mmol), the photo-orienting monomer compound shown in formula (1-2) (52.1 g, 170 mmol), and AIBN (1.64 g, 10.0 mmol) in NMP (153 g). In another reaction vessel equipped with a stirring device, NMP (102 g) was placed and heated to 60°C. After heating, the monomer mixture solution was added dropwise over 2 hours at 60°C under a nitrogen atmosphere to prepare the reaction solution. The reaction solution temperature was maintained at 60°C and stirred for 12 hours. After 12 hours, the reaction liquid was poured into a methanol / pure water mixed solvent to precipitate the polymer. After filtering off the precipitated polymer, it was washed with methanol to obtain powdered liquid crystalline polymer P-3.

[0084] <Preparation of Liquid Crystalline Polymer Solution> (Preparation Example Q-1: Preparation of Liquid Crystalline Polymer Solution Q-1) Liquid crystalline polymer P-1 (1.80 g), solvent CPN (8.20 g), and surfactant F563 (9.0 mg) were added to a reaction vessel equipped with a stirring device, and the mixture was stirred at room temperature to dissolve the liquid crystalline polymer P-1. Next, the solution was filtered through a 5.0 μm pore size filter to separate the solid (insoluble matter) from the liquid to obtain liquid crystalline polymer solution Q-1 (polymer concentration: 18% by mass). The obtained liquid crystalline polymer solution was used as a material for forming the following phase difference films (the same applies to Preparation Examples Q-2 to Q-9 below).

[0085] (Preparation Example Q-2: Preparation of Liquid Crystalline Polymer Solution Q-2) Liquid crystalline polymer solution Q-2 was prepared in the same manner as in Preparation Example Q-1, except that the amount of solvent CPN was changed to 7.90 g and HG (0.30 g) was added as a solvent.

[0086] (Preparation Example Q-3: Preparation of Liquid Crystalline Polymer Solution Q-3) Liquid crystalline polymer solution Q-3 was obtained in the same manner as in Preparation Example Q-2, except that the amount of solvent CPN was changed to 8.00 g and the amount of solvent HG was changed to 0.20 g.

[0087] (Preparation Example Q-4: Preparation of Liquid Crystalline Polymer Solution Q-4) Liquid crystalline polymer solution Q-4 was prepared in the same manner as in Preparation Example Q-2, except that the liquid crystalline polymer was changed to P-2 (1.80 g), the amount of the solvent CPN was changed to 7.90 g, and the solvent HG was changed to EC (0.30 g).

[0088] (Preparation Example Q-5: Preparation of Liquid Crystalline Polymer Solution Q-5) Liquid crystalline polymer solution Q-5 was prepared in the same manner as in Preparation Example Q-4, except that the amount of solvent CPN was changed to 7.70 g and the solvent EC was changed to cHexOH (0.50 g).

[0089] (Preparation Example Q-6: Preparation of Liquid Crystalline Polymer Solution Q-6) Liquid crystalline polymer solution Q-6 was prepared in the same manner as in Preparation Example Q-5, except that the amount of solvent CPN was changed to 7.90 g and the solvent cHexOH was changed to EC (0.30 g).

[0090] (Preparation Example Q-7: Preparation of Liquid Crystalline Polymer Solution Q-7) Liquid crystalline polymer solution Q-7 was prepared in the same manner as in Preparation Example Q-2, except that the liquid crystalline polymer was changed to P-3 (1.80 g), the amount of solvent CPN was changed to 7.20 g, and the solvent HG was changed to AmAc (1.00 g).

[0091] (Preparation Example Q-8: Preparation of Liquid Crystalline Polymer Solution Q-8) Liquid crystalline polymer solution Q-8 was prepared in the same manner as in Preparation Example Q-7, except that the amount of solvent CPN was changed to 8.20 g and AmAc was changed to PGMEA (1.00 g).

[0092] (Preparation Example Q-9: Preparation of Liquid Crystalline Polymer Solution Q-9) Liquid crystalline polymer solution Q-9 was prepared in the same manner as in Preparation Example Q-7, except that the solvent was changed to CPN (8.20 g) only.

[0093] <Preparation of Phase Difference Film> (Production Example R-1: Preparation of Phase Difference Film R-1) Liquid crystalline polymerization solution Q-9 was applied to the COP film using a bar coater to form a wet coating in a long length. The wet coating was dried at 45°C for 5 minutes to obtain a dry coating. Polarized ultraviolet light at 365 nm was applied to the dry coating using a metal halide lamp through a 365 nm bandpass filter and a polarizing filter at a rate of 800 mJ / cm². ２The film was irradiated with the integrated light intensity. Next, the coating film after irradiation with polarized ultraviolet light was heated at 140°C for 5 minutes. This yielded a COP-equipped phase difference film comprising a COP film and a long phase difference film R-1. The phase difference film R-1 exhibited refractive index characteristics nx > nz > ny. The film thickness of the phase difference film R-1 was 5.0 μm, the in-plane phase difference Re(550) was 270 nm, and the Nz coefficient was 0.25. The Re(450) / Re(550) of the phase difference film R-1 was 1.13.

[0094] (Production Examples R-2 to R-6: Preparation of Phase Difference Films R-2 to R-6) Phase difference films with COP (phase difference films R-2 to R-6) were obtained in the same manner as in Production Example R-1, except that the liquid crystalline polymerization solution was changed to the solution of Preparation Examples Q-1, Q-7, Q-8, Q-4, or Q-5 shown in Tables 1 to 2, and the drying conditions, film thickness, and heating conditions were adjusted to obtain Re(550) as shown in Tables 1 to 2. Each phase difference film exhibited the refractive index characteristics nx > nz > ny. The Re(450) / Re(550), Nz coefficient, and film thickness of each phase difference film are as shown in Tables 1 to 2.

[0095] (Production Examples R-7 to R-10, R-13 to R-14: Preparation of phase difference films R-7 to R-10, R-13 to R-14) Drying conditions, film thickness, and heating conditions were adjusted to obtain the in-plane phase difference Re(550) shown in Tables 1 to 2, and COP-attached phase difference films were obtained in the same manner as in Production Example R-1 using the polymerizable solution of Preparation Example Q-2. Each phase difference film exhibited refractive index characteristics nx > nz > ny. The Re(450) / Re(550), Nz coefficient, and film thickness of each phase difference film are shown in Tables 1 to 2.

[0096] (Production Examples R-11, R-12: Preparation of Phase Difference Films R-11, R-12) Except for changing the liquid crystalline polymerization solution to the solution of Preparation Example Q-4 or Q-3 and adjusting the drying conditions, film thickness, and heating conditions to achieve Re(550) as shown in Tables 1 and 2, a COP-equipped phase difference film (phase difference film R-11 or phase difference film R-12) was obtained in the same manner as in Production Example R-7. Each phase difference film exhibited a refractive index characteristic of nx > nz > ny. The Re(450) / Re(550), Nz coefficient, and film thickness of each phase difference film are shown in Tables 1 and 2.

[0097] (Manufacturing Example R-15: Manufacturing of Phase Difference Film R-15) Liquid crystalline polymerization solution Q-6 was applied to a COP film using a bar coater to form a wet coating in a long length. The wet coating was dried at 45°C for 5 minutes to obtain a dry coating. The dry coating was formed in a long length. Polarized ultraviolet light at 365 nm was applied to the dry coating using a metal halide lamp through a 365 nm bandpass filter and a polarizing filter at a rate of 1600 mJ / cm². ２ The film was irradiated with the integrated light intensity. Next, the coating film after irradiation with polarized ultraviolet light was heated at 140°C for 5 minutes. This yielded a phase difference film with a COP (Cellulose Optic Spectrometer) comprising a long phase difference film R-15. The phase difference film R-15 exhibited refractive index characteristics nx > nz > ny. The film thickness of the phase difference film R-15 was 1.8 μm, the in-plane phase difference Re(550) was 130 nm, and the Nz coefficient was 0.50.

[0098] (Manufacturing Examples R-16 to R-20: Manufacturing of Phase Difference Films R-16 to R-20) Drying conditions, film thickness, and heating conditions were adjusted to achieve the in-plane phase difference Re(550) shown in Tables 1 to 2. Using the polymerizable solution of Preparation Example Q-6, COP-attached phase difference films (phase difference films R-16 to R-20) were obtained in the same manner as in Manufacturing Example R-15. Each phase difference film exhibited a refractive index characteristic of nx > nz > ny. The Re(450) / Re(550), Nz coefficient, and film thickness of each phase difference film are shown in Tables 1 to 2.

[0099] (Production Example CR-1: Preparation of Phase Difference Film CR-1) (i) Synthesis of Resin Material (Polyarylate) In a reaction vessel equipped with a stirring device, 27.0 kg of 2,2-bis(4-hydroxyphenyl)-4-methylpentane and 0.8 kg of tetrabutylammonium chloride were dissolved in 250 L of sodium hydroxide solution. To this solution, a solution of 13.5 kg of terephthalic acid chloride and 6.30 kg of isophthalic acid chloride dissolved in 300 L of toluene was added all at once while stirring, and the mixture was stirred at room temperature for 90 minutes to obtain a polycondensation solution. The polycondensation solution was then separated by standing separation to separate the toluene solution containing polyarylate. Next, the separated liquid was washed with acetic acid water, then with deionized water, and then added to methanol to precipitate polyarylate. The precipitated polyarylate was filtered and dried under reduced pressure to obtain 34.1 kg of white polyarylate (yield 92%).

[0100] (ii) Preparation of phase difference film A coating solution was prepared by dissolving 10 kg of the polyarylate obtained above in 73 kg of toluene. Then, the coating solution was directly applied to a shrinkable film (longitudinal uniaxially oriented polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name "Noblen"), and the coating film was dried at a drying temperature of 60°C for 5 minutes and then at 80°C for 5 minutes to form a laminate of shrinkable film / birefringence layer. The obtained laminate was stretched using a simultaneous biaxial stretching machine at a stretching temperature of 155°C with a shrinkage ratio of 0.70 in the MD direction and 1.15 times in the TD direction to form a phase difference film on the shrinkable film. Then, the phase difference film was peeled off the shrinkable film. This obtained the phase difference film CR-1. The phase difference film had a refractive index characteristic of nx > nz > ny. The film thickness of the phase difference film was 15.0 μm, Re(550) = 270 nm, and Nz = 0.25. The Re(450) / Re(550) ratio of the phase difference film was 1.10.

[0101] (Manufacturing Example CR-2: Preparation of Phase Difference Film CR-2) 10 kg of polyarylate synthesized in (i) above was dissolved in 73 kg of toluene to prepare a coating solution. The coating solution was then directly applied to a shrinkable film (longitudinal uniaxially oriented polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name "Noblen"), and the coating film was dried at a drying temperature of 60°C for 5 minutes and then at 80°C for 5 minutes to form a laminate of shrinkable film / birefringence layer. The obtained laminate was stretched using a simultaneous biaxial stretching machine at a stretching temperature of 155°C with a shrinkage ratio of 0.80 in the MD direction and 1.17 times in the TD direction to form a phase difference film on the shrinkable film. Next, the phase difference film was peeled off the shrinkable film. This obtained the phase difference film CR-2. The phase difference film had refractive index characteristics nx > nz > ny. The phase difference film had a thickness of 17.0 μm, Re(550) = 240 nm, and Nz = 0.50. The Re(450) / Re(550) ratio of the phase difference film was 1.10.

[0102] (Manufacturing Example CR-3: Preparation of Phase Difference Film CR-3) 10 kg of polyarylate synthesized in (i) above was dissolved in 73 kg of toluene to prepare a coating solution. Then, this coating solution was directly applied to a shrinkable film (longitudinal uniaxially oriented polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name "Noblen"), and the coating film was dried at a drying temperature of 60°C for 5 minutes and then at 80°C for 5 minutes to form a laminate of shrinkable film / birefringence layer. The obtained laminate was stretched using a simultaneous biaxial stretching machine at a stretching temperature of 155°C with a shrinkage ratio of 0.81 in the MD direction and 1.15 times in the TD direction to form a phase difference film on the shrinkable film. Next, the phase difference film was peeled off the shrinkable film. This obtained the phase difference film CR-3. The phase difference film had refractive index characteristics nx > nz > ny. The phase difference film had a thickness of 8.0 μm, Re(550) = 120 nm, and Nz = 0.50. The Re(450) / Re(550) ratio of the phase difference film was 1.10.

[0103] (Manufacturing Example CR-4: Preparation of Phase Difference Film CR-4) 10 kg of polyarylate synthesized in (i) above was dissolved in 73 kg of toluene to prepare a coating solution. The coating solution was then directly applied to a shrinkable film (longitudinal uniaxially oriented polypropylene film, manufactured by Tokyo Ink Co., Ltd., trade name "Noblen"), and the coating film was dried at a drying temperature of 60°C for 5 minutes and then at 80°C for 5 minutes to form a laminate of shrinkable film / birefringence layer. The obtained laminate was stretched using a simultaneous biaxial stretching machine at a stretching temperature of 155°C with a shrinkage ratio of 0.88 in the MD direction and 1.19 in the TD direction to form a phase difference film on the shrinkable film. Next, the phase difference film was peeled off the shrinkable film. This obtained the phase difference film CR-4. The phase difference film had refractive index characteristics nx > nz > ny. The phase difference film had a thickness of 17.0 μm, Re(550) = 270 nm, and Nz = 0.75. The Re(450) / Re(550) ratio of the phase difference film was 1.10.

[0104] [Example 1] (Preparation of polarizing plate with optical compensation layer) The TAC film was peeled off from the polarizing plate of production example Pol-1, and the phase difference film of production example R-1 was used as the first optical compensation layer and bonded to the polarizer by irradiating with an electron beam using an electron beam-curable acrylic adhesive in a roll-to-roll manner. Next, the COP film was peeled off from the first optical compensation layer, and the phase difference film R-7 of production example R-7 (opposite side from the COP film) was used as the second optical compensation layer and bonded to the first optical compensation layer by irradiating with an electron beam using an electron beam-curable acrylic adhesive in a roll-to-roll manner. Next, the COP film was peeled off from the second optical compensation layer, and the phase difference film R-7 of production example R-7 (opposite side from the COP film) was used as the third optical compensation layer and bonded to the second optical compensation layer by irradiating with an electron beam using an electron beam-curable acrylic adhesive in a roll-to-roll manner. Next, the COP film was peeled off the third optical compensation layer, and the phase difference film R-15 of manufacturing example R-15 (opposite side from the COP film) was used as the fourth optical compensation layer. The fourth optical compensation layer and the third optical compensation layer were bonded together by irradiating them with an electron beam using a roll-to-roll method via an electron beam-curable acrylic adhesive. Then, the COP film was peeled off the fourth optical compensation layer. The bonding of each layer was performed so that the angle between the absorption axis of the polarizer and the slow axis of each optical compensation layer was as shown in the "Axis Angle" column of Table 1. Specifically, in Example 1, the polarizer plate and the first optical compensation layer were bonded together such that the absorption axis of the polarizer and the slow axis of the first optical compensation layer were substantially orthogonal; the first optical compensation layer and the second optical compensation layer were bonded together such that the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer was 96°; the second optical compensation layer and the third optical compensation layer were bonded together such that the angle between the absorption axis of the polarizer and the slow axis of the third optical compensation layer was 123°; and the third optical compensation layer and the fourth optical compensation layer were bonded together such that the angle between the absorption axis of the polarizer and the slow axis of the fourth optical compensation layer was 9°. In this way, a polarizer plate with optical compensation layers was obtained having the configuration of polarizer plate (protective layer / polarizer) / first optical compensation layer / second optical compensation layer / third optical compensation layer / fourth optical compensation layer. The obtained polarizer plate with optical compensation layers was subjected to the evaluation in (3) above, and the color was confirmed by visual inspection.

[0105] (Preparation and Evaluation of Evaluation Panels) The obtained polarizing plate with optical compensation layer was cut to a predetermined size of 30 mm x 30 mm to obtain a test sample of the polarizing plate with optical compensation layer. An adhesive layer was formed on the fourth optical compensation layer side of the test sample using an acrylic adhesive. An organic EL display device (manufactured by Samsung, product number "Galaxy®-S-6") was disassembled and the organic EL panel was removed. The adhesive layer formed on the above test sample (polarizing plate with optical compensation layer) was bonded to this organic EL panel to obtain an organic EL panel (evaluation panel). The evaluation panel was subjected to the evaluation described in (4) above. The results are shown in Table 1.

[0106] [Examples 2-10] Polarizing plates with optical compensation layers were manufactured in the same manner as in Example 1, except that the first optical compensation layer, second optical compensation layer, third optical compensation layer, and fourth optical compensation layer were replaced with phase difference films from the manufacturing examples shown in Tables 1 and 2, and the axial angles of each layer were changed to the axial angles shown in Tables 1 and 2. The obtained polarizing plates with optical compensation layers were subjected to the evaluation described in (3) above, in the same manner as in Example 1, and the color was confirmed by visual inspection. The obtained polarizing plates with optical compensation layers were cut to predetermined dimensions in the same manner as in Example 1 to obtain test samples, and the third optical compensation layer side of the test samples was bonded to an organic EL panel via an adhesive layer to obtain evaluation panels. The evaluation panels were subjected to the same evaluation as in Example 1. The results are shown in Tables 1 and 2.

[0107] [Comparative Example 1] (Preparation of Polarizing Plate with Optical Compensation Layer) Using the polarizing plate of production example Pol-1, phase difference film CR-1 as the first optical compensation layer, phase difference film CR-2 as the second and third optical compensation layers, and phase difference film CR-3 as the fourth optical compensation layer, each was cut to a predetermined size, and the polarizer surface obtained by peeling the TAC film from the polarizing plate and the first optical compensation layer; the first optical compensation layer and the second optical compensation layer; the second optical compensation layer and the third optical compensation layer; and the third optical compensation layer and the fourth optical compensation layer were sequentially bonded together via an acrylic adhesive. In this way, a polarizing plate with an optical compensation layer was obtained having the configuration of polarizing plate (protective layer / polarizer) / first optical compensation layer / second optical compensation layer / third optical compensation layer / fourth optical compensation layer. Furthermore, the first optical compensation layer was cut so that the absorption axis of the polarizer and the slow axis of the first optical compensation layer were substantially orthogonal to each other in the polarizing plate with the optical compensation layer; the second optical compensation layer was cut so that the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer was 96°; the third optical compensation layer was cut so that the angle between the absorption axis of the polarizer and the slow axis of the third optical compensation layer was 123°; and the third optical compensation layer was cut so that the angle between the absorption axis of the polarizer and the slow axis of the third optical compensation layer was 9°. The obtained polarizing plates with optical compensation layers were subjected to the evaluation in (3) above in the same manner as in Example 1, and the color was confirmed by visual inspection.

[0108] (Preparation of evaluation panel) The polarizing plate with optical compensation layer obtained above was cut to a predetermined size in the same manner as in Example 1 to obtain a test sample. The third optical compensation layer side of the test sample was bonded to an organic EL panel via an adhesive layer to obtain an evaluation panel. The evaluation panel was subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0109] [Comparative Examples 2-4] Except for using the phase difference films of the manufacturing examples shown in Table 2 as the first, second, third, and fourth optical compensation layers, and changing the axial angles to the angles shown in Table 2, an optical compensation layer polarizing plate was obtained in the same manner as in Comparative Example 1, having the configuration of polarizing plate (protective layer / polarizer) / second optical compensation layer / third optical compensation layer / fourth optical compensation layer. Furthermore, an evaluation panel (organic EL panel) was prepared in the same manner as in Example 1, except that this optical compensation layer polarizing plate was used. The obtained optical compensation layer polarizing plate and organic EL panel were subjected to the same evaluation as in Example 1. The results are shown in Table 2.

[0110]

[0111]

[0112] <Evaluation of Polarizing Plate with Optical Compensation Layer by Simulation> Simulations were performed using the characteristics of a polarizing plate and a polarizing plate with optical compensation layers, which are equipped with the in-plane phase difference Re(550), Nz coefficient, axis angle, and the first, second, third, and fourth optical compensation layers having Re(450) / Re(550) in that order, as shown in Table 3. The same physical properties as those used in the above-mentioned manufacturing example Pol-1 were adopted for the polarizing plate. For the simulation, "LCD MASTER Ver. 6.084" manufactured by Syntec Corporation was used. Reflectance characteristics were simulated using the extended functions of LCD MASTER, and the reflected hue and oblique reflectance in oblique directions were evaluated. Specifically, the reflected hue (x,y) and reflectance were evaluated for azimuth angles (φ) of 30° and 210°, and for polar angles (Θ) of 42° and 49° at azimuth angles (φ) of 150° and 330°. The reflectance in oblique directions was calculated by excluding surface reflection. Based on the obtained reflectance hue and reflectance results, each was evaluated according to the following criteria. The results are shown in Table 3.・Reflectance Hue (x, y) A (Excellent): x ≤ 0.30 and y ≤ 0.30 B (Good): x ≤ 0.30 and 0.30 < y ≤ 0.37 C (Acceptable): 0.30 ≤ x ≤ 0.35 and y ≤ 0.37 D (Unacceptable): The highest value at θ in any φ is 0.35 ≤ x and y ≤ 0.30 E (Poor): The highest value at θ in any φ is 0.35 ≤ x and 0.30 ≤ y ・Reflectance Y% A (Excellent): Y ≤ 0.15 B (Good): 0.15 < Y < 25 C (Acceptable): 0.25 ≤ Y < 0.35 D (Unacceptable): 0.35 < Y < 0.5 E (Poor): The highest value at θ in any φ is 0.50 ≤ Y

[0113]

[0114] The polarizing plate with an optical compensation layer according to an embodiment of the present invention is suitably used in organic EL panels.

[0115] 10 Polarizer 20 Protective layer 30 First optical compensation layer 40 Second optical compensation layer 50 Third optical compensation layer 60 Fourth optical compensation layer 100 Polarizing plate with optical compensation layer

Claims

1. A polarizer comprising: a polarizer; a first optical compensation layer disposed adjacent to the polarizer; a second optical compensation layer disposed adjacent to the first optical compensation layer; a third optical compensation layer disposed adjacent to the second optical compensation layer; and a fourth optical compensation layer as the outermost optical compensation layer disposed adjacent to the third optical compensation layer, wherein the first, second, third, and fourth optical compensation layers all exhibit refractive index characteristics of nx > nz > ny and satisfy 1.10 < Re(450) / Re(550) ≤ 1.40, the Nz coefficient of the first optical compensation layer is 0.10 or more and 0.40 or less or 0.65 or more and 0.85 or less, and the Nz coefficients of the second, third, and fourth optical compensation layers are all 0.40 or more and 0.60 or less, a polarizer with optical compensation layers: Here, Re(450) and Re(550) represent the in-plane phase difference measured with light at wavelengths of 450 nm and 550 nm at 23°C, respectively.

2. The polarizing plate with an optical compensation layer according to claim 1, wherein the reflected hues (x, y) for azimuth angles (φ) of 30° and 210°, and for polar angles (Θ) = 42° and 49° at 150° and 330°, all satisfy 0 < x < 0.35 and 0 < y < 0.

35.

3. The Re(550) of the first optical compensation layer is 190 nm to 310 nm, and the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is in the range of 90° ± 10° or 0° ± 10°; the Re(550) of the second optical compensation layer is 200 nm to 310 nm, and the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer is 80° to 110°; the Re(550) of the third optical compensation layer is 210 nm to 270 nm, and the angle between the absorption axis of the polarizer and the slow axis of the third optical compensation layer is 100° to 130°; The polarizing plate with an optical compensation layer according to claim 1, wherein the Re(550) of the fourth optical compensation layer is 80 nm to 160 nm, and the angle between the absorption axis of the polarizer and the slow axis of the fourth optical compensation layer is -20° to 25°.

4. The polarizing plate with optical compensation layers according to claim 1, wherein the thickness of each of the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer is 0.1 μm or more and less than 10.0 μm.

5. The polarizing plate with optical compensation layers according to claim 1, wherein at least one of the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer contains a liquid crystalline compound.

6. The polarizing plate with an optical compensation layer according to claim 5, wherein the liquid crystalline compound includes a compound having photo-alignment properties.

7. The polarizing plate with an optical compensation layer according to claim 6, wherein the photo-oriented compound is at least one compound selected from the group consisting of cinnamic acid, cinnamic acid derivatives, azobenzene, azobenzene derivatives, coumarin, coumarin derivatives, chalcone, chalcone derivatives, stilbene, and stilbene derivatives.

8. A method for manufacturing a polarizing plate with an optical compensation layer according to claim 1, comprising: applying a liquid crystalline compound and irradiating the liquid crystalline compound with polarized ultraviolet light to orient it, thereby obtaining at least one of a first optical compensation layer, a second optical compensation layer, a third optical compensation layer, and a fourth optical compensation layer.

9. A method for manufacturing a polarizing plate with optical compensation layers according to claim 8, comprising bonding a polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer by roll-to-roll.

10. An image display device comprising a polarizing plate with an optical compensation layer according to any one of claims 1 to 7.

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