Optical laminate and image display apparatus

Abstract

To provide an optical laminate which presents less color unevenness caused by diagonal burn-in even when kept under a high-temperature environment in a lit state for a long period of time, in a case where the laminate is applied to an image display device.SOLUTION: An optical laminate according to an embodiment of the present invention includes: a polarizing plate including a polarizer; and a retardation layer, the retardation layer having a circularly polarized light function or an elliptically polarized light function, the optical laminate satisfying the condition that, after the optical laminate is placed in an environment at 95°C for 120 hours, b*Ave, which is the average value of b values of respective hues at azimuth angles of 0°, 45°, 90°, and 135° as viewed from a polar angle of 60°, is less than 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), are rapidly becoming popular. In image display devices, in order to realize image display and improve image display performance, a color filter is disposed, a colored layer is provided on the image display panel, and / or an optical laminate including a polarizing plate and a retardation layer is widely used. However, when such an optical laminate is applied to an image display device, if the image display device is left in a high-temperature environment for a long time while being turned on, color unevenness due to image sticking may occur on the screen. Such color unevenness due to image sticking may be noticeable when viewed from an oblique direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-139865 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-149191 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide an optical laminate that, when applied to an image display device, can suppress color unevenness due to image sticking in oblique directions even when the image display device is left in a high-temperature environment for a long period of time in a turned-on state. [Means for solving the problem]

[0005] [1] An optical laminate according to an embodiment of the present invention includes a polarizing plate including a polarizer and a retardation layer. The retardation layer has a circular polarization function or an elliptically polarizing function. After the optical laminate was left in an environment at a temperature of 95°C for 120 hours, the hue b at azimuth angles of 0°, 45°, 90°, and 135° as viewed from a polar angle of 60° was measured. * The average value of b * Ave is less than 1. [2] In the above [1], the in-plane retardation Re(550) of the retardation layer is 100 nm or more and 200 nm or less, the angle between the slow axis and the absorption axis of the polarizer is 40° or more and 50° or less, and the retardation layer satisfies the relationship Re(650)>Re(550)>Re(450). [3] In the above [1], the retardation layer has a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer, wherein the first liquid crystal alignment solidified layer has an in-plane retardation Re(550) of 200 nm or more and 300 nm or less, and the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°, and the second liquid crystal alignment solidified layer has an in-plane retardation Re(550) of 100 nm or more and 200 nm or less, and the angle between its slow axis and the absorption axis of the polarizer is 70° to 80°. [4] In the above [2], the retardation layer is a stretched film. [5] In any one of [1] to [4] above, the optical laminate further comprises an optical compensation layer between the polarizing plate and the retardation layer, the optical compensation layer having a refractive index characteristic of nx=ny>nz, and a thickness direction retardation Rth(550) of the optical compensation layer being 10 nm or more. [6] In any of [1] to [5] above, after the optical laminate is placed in an environment at a temperature of 95°C for 120 hours, each hue b at azimuth angles of 0°, 45°, 90° and 135° as viewed from a polar angle of 60° * The average value of b * Ave is less than or equal to 0. [7] According to another aspect of the present invention, there is provided an image display device, comprising the optical laminate according to any one of [1] to [6] above. [Effects of the Invention]

[0006] According to an embodiment of the present invention, an optical laminate can be provided that, when applied to an image display device, can suppress color unevenness caused by oblique burn-in even when the image display device is left in a high-temperature environment for a long period of time while turned on, and an image display device using this optical laminate can be provided. [Brief explanation of the drawings]

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

[0008] Representative embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. The drawings are schematic for ease of understanding, and differ from the actual length, width, thickness, and ratios of each layer. In this specification, "A and / or B" means either "A," "B," or "A and B."

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

[0010] A. Overall structure of the optical laminate 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The illustrated optical laminate 100 includes a polarizing plate 10 including a polarizer 11 and a retardation layer 20. The polarizing plate 10 and the retardation layer 20 are bonded together via any appropriate adhesive layer (e.g., an adhesive layer or a pressure-sensitive adhesive layer; not shown). The polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one surface of the polarizer 11 (the side opposite the retardation layer 20 of the polarizer 11), and a second protective layer 13 disposed on the other surface of the polarizer 11 (the side facing the retardation layer 20). Depending on the purpose, at least one of the first protective layer 12 and the second protective layer 13 may be omitted. Therefore, the polarizing plate may be a so-called double-protected polarizing plate, a so-called single-protected polarizing plate, or may be composed of a polarizer alone. In the optical laminate 100, the side of the first protective layer 12 opposite the polarizer 11 is the viewing side. The optical laminate 100 in the illustrated example further includes a hard coat layer 14 on the side of the first protective layer 12 opposite the polarizer 11. However, the hard coat layer 14 may be omitted.

[0011] The retardation layer 20 has a circular polarization function or an elliptically polarization function. The retardation layer 20 can have a circular polarization function or an elliptically polarization function, typically by being combined with a polarizing plate (substantially a polarizer). With such a configuration, an optical laminate having good antireflection properties can be obtained.

[0012] In this embodiment, after the optical laminate was placed in an environment at a temperature of 95°C for 120 hours, the hue b * The average value of b * Ave is typically less than 1. With this configuration, when the optical laminate according to the embodiment of the present invention is applied to an image display device, color unevenness caused by image sticking from an oblique direction can be suppressed even if the image display device is left in a high-temperature environment in a turned-on state for a long period of time. More specifically, when the optical laminate is conventionally applied to a screen display device, image sticking may occur on the image display panel of the image display device if the image display device is left in a high-temperature environment (e.g., 90°C or higher) in a turned-on state for a long period of time (e.g., 100 hours or more). When image sticking occurs on the image display panel, the burned-in area appears yellowish, and the image display device has a yellowish hue. In other words, color unevenness caused by image sticking may appear. Such color unevenness caused by image sticking may be particularly noticeable when viewed from an oblique direction. Although color unevenness due to image sticking can be suppressed to some extent by providing an image display device with a color filter having a colored layer containing a pigment or by providing an organic EL element or the like of a display panel of the image display device with a light-absorbing layer (photochromic layer), it is difficult to suppress color unevenness due to image sticking in an optical laminate including a polarizing plate and a retardation layer. In contrast, the optical laminate according to the embodiment of the present invention has a hue b at azimuth angles of 0°, 45°, 90° and 135° as viewed from a polar angle of 60° after the optical laminate is placed in an environment at a temperature of 95°C for 120 hours. * The average value of b * Aveis less than 1. With this configuration, the optical laminate can have a bluish hue after being left in a high-temperature environment for a long period of time. Therefore, even if burn-in occurs on the image display panel when the image display device is left in a high-temperature environment for a long period of time while turned on, the bluish hue of the optical laminate can offset the yellowish hue caused by the burn-in. As a result, even if burn-in occurs on the image display panel, the hue of the black display of the image display device when viewed from an oblique direction can be a neutral black. Note that it is sufficient for the optical laminate to have a bluish hue after being left in a high-temperature environment for a long period of time; it may or may not have a bluish hue before being placed in the high-temperature environment.

[0013] In this specification, a polar angle of 60° refers to a direction that is 60° from the main surface (0°) when the normal direction of the optical laminate is 90°. In this specification, the direction of a polar angle of 60° may be used to mean an oblique direction. In this specification, the term "azimuth angle" refers to the angle formed between the absorption axis direction of the polarizer of the optical laminate as a reference and one direction in the main surface of the optical laminate. Hue b * The value is L * a * b * Color space b * The hue b value is measured in accordance with JIS Z 8722:2009 using an appropriate spectrophotometric measurement device such as a display measurement system or a spectrophotometer. In this specification, the term "variable hue b" refers to the value of the hue b at azimuth angles of 0°, 45°, 90°, and 135° as viewed from a polar angle of 60° after the optical laminate is left in an environment at a temperature of 95°C for 120 hours. * The "average value of hue b at a polar angle of 60°" is simply * "Average value of" or "Average value b * Ave "It is sometimes referred to as ".

[0014] Average value of optical laminate b * AveAs described above, is typically less than 1, preferably 0 or less, more preferably -1.0 or less, even more preferably -2.0 or less, particularly preferably -3.0 or less, and most preferably -4.0 or less. * Ave can be adjusted by appropriately adjusting the type of retardation film used in the retardation layer, the retardation, axial angle, and thickness of the retardation layer, and / or the type and Rth of the optical compensation layer depending on the purpose.

[0015] In one embodiment, the in-plane retardation Re(550) of the retardation layer 20 is 100 nm or more and 200 nm or less, the angle between the slow axis of the retardation layer 20 and the absorption axis of the polarizer 11 is 40° or more and 50° or less, and the retardation layer 20 satisfies the relationship Re(650)>Re(550)>Re(450). With this configuration, the retardation layer can function as a so-called λ / 4 plate and exhibit wavelength dependence of reverse dispersion (hereinafter also referred to as reverse dispersion wavelength characteristics) in which the retardation value increases depending on the wavelength of the measurement light. As a result, when the optical laminate is applied to an image display device, the optical laminate can have excellent anti-reflection performance in oblique directions and can further achieve excellent anti-reflection function in oblique directions over a very wide wavelength range. The in-plane retardation Re(550) of the retardation layer 20 is preferably 110 nm or more and 180 nm or less, more preferably 120 nm or more and 160 nm or less, and even more preferably 130 nm or more and 150 nm or less. The angle between the slow axis of the retardation layer 20 and the absorption axis of the polarizer 11 is preferably 42° or more and 48° or less, more preferably 44° or more and 46° or less. The Re(650) / Re(550) of the retardation layer is, for example, 1.0 or more and less than 1.15, preferably 1.02 or more and 1.13 or less, and more preferably 1.03 or more and 1.10 or less. The Re(450) / Re(550) is, for example, 0.7 or more and 0.95 or less, preferably 0.75 or more and 0.92 or less, and more preferably 0.8 or more and 0.9 or less. In this embodiment, the retardation layer may be a liquid crystal alignment solidified layer, or a film produced by stretching a resin film. In this specification, the term "liquid crystal alignment solidified layer" refers to a layer in which liquid crystal compounds are oriented in a predetermined direction within the layer and the alignment state is fixed. The term "liquid crystal alignment solidified layer" is a concept that encompasses an alignment hardened layer obtained by hardening a liquid crystal monomer. In this specification, a film produced by stretching a resin film may be referred to as a "stretched film."

[0016] In another embodiment, the retardation layer 20 has a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer. The in-plane retardation Re(550) of the first liquid crystal alignment solidified layer is typically 200 nm or more and 300 nm or less; the in-plane retardation Re(550) of the second liquid crystal alignment solidified layer is typically 100 nm or more and 200 nm or less. In this case, the angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer is typically 10° to 20°; the angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer is typically 70° to 80°. With this configuration, when the optical laminate is applied to an image display device, the optical laminate can have excellent anti-reflection performance in oblique directions. The in-plane retardation Re(550) of the first liquid crystal alignment solidified layer is preferably 220 nm to 290 nm, more preferably 260 nm to 280 nm; the Re(550) of the second liquid crystal alignment solidified layer is preferably 110 nm to 180 nm, more preferably 130 nm to 150 nm. The angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 12° to 18°, more preferably 14° to 16°. The angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 72° to 78°, more preferably 74° to 76°. The direction of the slow axis of the first liquid crystal alignment solidified layer can be controlled by an alignment treatment. The angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer and the angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer may be reversed.

[0017] Figure 2 is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. The optical laminate 101 in the illustrated example includes a polarizing plate 10 including a polarizer 11, an optical compensation layer 30, and a retardation layer 20 in this order. That is, the optical laminate 101 in the illustrated example further includes an optical compensation layer 30 between the polarizing plate 10 and the retardation layer 20. The polarizing plate 10 and the optical compensation layer 30, and the optical compensation layer 30 and the retardation layer 20 are bonded to each other via any appropriate adhesive layer (for example, an adhesive layer, an adhesive layer: not shown).

[0018] The polarizing plate 10 and the retardation layer 20 in the optical laminate 101 in the illustrated example may have the same configuration as the polarizing plate 10 and the retardation layer 20 in the above-described optical laminate 100.

[0019] Typically, the optical compensation layer 30 exhibits a refractive index characteristic of nx = ny > nz. A layer having a refractive index characteristic of nx = ny > nz may be referred to as a "negative C plate". Here, "nx = ny" includes not only the case where nx and ny are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, nx < ny may occur. The same applies to "ny = nz" and "nx = ny" in the relationships of nx > ny = nz and nz > nx = ny described later.

[0020] Typically, the retardation Rth(550) in the thickness direction of the optical compensation layer 30 is 10 nm or more, preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit of the retardation Rth(550) in the thickness direction of the optical compensation layer 30 may be, for example, 50 nm. In the present embodiment, after the optical laminate is left in an environment at a temperature of 95°C for 120 hours, the b value at azimuth angles of 0°, 45°, 90°, and 135° viewed from a polar angle of 60° * The average value of the values is b [[ID=​​​​The color may have a bluish hue, and the blueness of the hue itself may be improved. As a result, the above-described effects of the embodiment of the present invention may be more pronounced.

[0021] Average value b of the optical laminate according to this embodiment * Ave is preferably −1 or less, more preferably −2 or less, and even more preferably −3 or less. * Ave As described above, can be adjusted by appropriately adjusting the type of retardation film used in the retardation layer, the retardation, axial angle, and thickness of the retardation layer, and / or the type and Rth of the optical compensation layer depending on the purpose.

[0022] The optical laminate may be in a long or sheet-like shape. In this specification, "long" means an elongated shape in which the length is sufficiently longer than the width, and includes, for example, an elongated shape in which the length is 10 times or more, preferably 20 times or more, the width. A long optical laminate can be wound into a roll. A long optical laminate can be produced, for example, by a so-called roll-to-roll process. A sheet-like optical laminate may be produced by cutting a long optical laminate into a predetermined size (typically, a size corresponding to an image display device), or by bonding together each component (each layer) cut into a predetermined size.

[0023] In practice, the optical laminate has any appropriate pressure-sensitive adhesive layer (not shown) as the outermost layer on the retardation layer side (for example, on the image display panel side when applied to an image display device), and can be attached to the image display panel. It is preferable that a release liner is temporarily attached to the surface of the pressure-sensitive adhesive layer until the optical laminate is used. Temporarily attaching the release liner protects the pressure-sensitive adhesive layer and enables the optical laminate to be formed into a roll.

[0024] The components of the optical laminate will be described below. B. Polarizing plate B-1.Polarizer The polarizer 11 is typically made of a polyvinyl alcohol (PVA) resin film containing a dichroic substance (e.g., iodine). Examples of PVA resins include polyvinyl alcohol, partially formalized polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and partially saponified ethylene-vinyl acetate copolymer.

[0025] The PVA resin preferably contains an acetoacetyl-modified PVA resin. With this configuration, a polarizer having desired mechanical strength can be obtained. The amount of the acetoacetyl-modified PVA resin is preferably 5% by weight to 20% by weight, and more preferably 8% by weight to 12% by weight, based on 100% by weight of the entire PVA resin. If the amount is within this range, a polarizer having better mechanical strength can be obtained.

[0026] The polarizer preferably contains iodide or sodium chloride (sometimes collectively referred to as a halide). Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. The content of the halide in the polarizer is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, relative to 100 parts by weight of the PVA-based resin. In the manufacturing method described below, the halide is blended into a coating liquid that forms a PVA-based resin layer, which is a precursor of the polarizer, and can be finally introduced into the polarizer. Introducing a halide into the polarizer can improve the orientation of PVA molecules in the polarizer, thereby achieving a polarizer with excellent optical properties (typically, both a high degree of polarization and a high single-unit transmittance).

[0027] The polarizer preferably exhibits absorptive dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is preferably 41.0% to 46.0%, and more preferably 42.0% to 45.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more. According to an embodiment of the present invention, even if the single transmittance is within the above range, the degree of polarization can be maintained within this range.

[0028] 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 retardation layer (for example, a liquid crystal alignment solidified layer), it is possible to significantly reduce the thickness of the optical laminate. Furthermore, if the thickness of the polarizer is within the above range, curling during heating can be effectively suppressed, and good appearance durability during heating can be obtained.

[0029] The polarizer can be produced by any appropriate method. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0030] Specific examples of polarizers made of a single-layer resin film include hydrophilic polymer films such as PVA films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films that have been dyed with iodine or a dichroic substance such as a dichroic dye and stretched, and polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films. A polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching it is preferred because of its excellent optical properties.

[0031] The dyeing with iodine is carried out, for example, by immersing the PVA film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment or while dyeing. Alternatively, the PVA film may be stretched and then dyed. If necessary, the PVA film may be subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, or the like. For example, by immersing the PVA film in water and washing it before dyeing, it is possible to wash away dirt and antiblocking agents on the surface of the PVA film, and also to swell the PVA film, thereby preventing uneven dyeing.

[0032] Specific examples of polarizers obtained using laminates include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying the resin substrate to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; and then stretching and dyeing the laminate to convert the PVA-based resin layer into a polarizer. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically involves immersing the laminate in a boric acid aqueous solution and stretching it. Furthermore, the stretching may further include, if necessary, in-air stretching of the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the boric acid aqueous solution. Additionally, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment by heating while being transported in the longitudinal direction, thereby shrinking the laminate by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an auxiliary in-air stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment, in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA, even when PVA is coated on a thermoplastic resin, thereby achieving high optical properties. Furthermore, by simultaneously increasing the orientation of PVA in advance, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the subsequent dyeing or stretching steps can be prevented, thereby achieving high optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, the disordering of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through treatment steps in which the laminate is immersed in a liquid, such as a dyeing treatment and an underwater stretching treatment. Furthermore, the optical properties can be improved by shrinking the laminate in the width direction through the drying shrinkage treatment.The obtained resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or any suitable protective layer may be laminated on the surface obtained by peeling the resin substrate from the resin substrate / polarizer laminate or on the surface opposite to the peeled surface, depending on the purpose. Details of the method for producing such a polarizer are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The entire disclosures of these publications are incorporated herein by reference.

[0033] B-2.Protective layer The protective layers (first protective layer 12 and second protective layer 13) are made of any appropriate resin film. Typical materials for the resin film include cellulose-based resins such as triacetyl cellulose (TAC) and cellulose acylate, cycloolefin-based resins such as polynorbornene, (meth)acrylic resins, polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin-based resins such as polyethylene, and polycarbonate-based resins. Typical examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. Examples of (meth)acrylic resins having a lactone ring structure are described in, for example, JP 2000-230016 A, JP 2001-151814 A, JP 2002-120326 A, JP 2002-254544 A, and JP 2005-146084 A. These publications are incorporated herein by reference. From the viewpoint of ease of processing, etc., cellulose-based resins are preferred, and TAC is more preferred. From the viewpoint of obtaining a polarizing plate with low moisture permeability and excellent durability, cycloolefin-based resins and (meth)acrylic resins are preferred.

[0034] The optical laminate is typically placed on the viewing side of an image display device, and the first protective layer 12 (outer protective layer) is typically placed on the viewing side. Therefore, the first protective layer 12 may be subjected to a surface treatment as needed. Examples of surface treatments include hard coating treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment. Of these, hard coating treatment (formation of a hard coating layer) is preferred. In the illustrated example, a hard coating layer 14 is formed on the protective layer 12. The hard coating treatment may be combined with other surface treatments.

[0035] The hard coat layer 14 preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. If not formed by surface treatment, the hard coat layer 14 may be formed, for example, from any appropriate resin. The hard coat layer 14 is typically formed from an ultraviolet-curable resin. Examples of ultraviolet-curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based resins. The pencil hardness of the hard coat layer 14 can be, for example, 2H or more, preferably 3H or more, and more preferably 4H or more. The pencil hardness can be measured in accordance with JIS K 5600 5-4. The thickness of the hard coat layer 14 is, for example, 0.5 μm or more, preferably 1 μm or more, and for example, 20 μm or less, preferably 15 μm or less.

[0036] If necessary, the first protective layer 12 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, by imparting (elliptically) circular polarization or ultra-high phase difference). By performing such a treatment, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate can be suitably applied to image display devices that can be used outdoors.

[0037] In one embodiment, the second protective layer 13 (inner protective layer) is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm or more and 10 nm or less, and the retardation Rth(550) in the thickness direction is -10 nm or more and less than +10 nm.

[0038] The thickness of each of the first protective layer 12 and the second protective layer 13 is preferably 10 μm to 80 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 35 μm. If the first protective layer 12 has been surface-treated, the thickness of the protective layer 12 includes the thickness of the surface-treated layer.

[0039] C. Retardation layer C-1. Overview of the retardation layer As described above, the retardation layer has a circular polarization function or an elliptically polarization function. The retardation layer can typically have a circular polarization function or an elliptically polarization function when combined with a polarizing plate (substantially a polarizer). With such a configuration, an optical laminate having good anti-reflection properties can be obtained. The retardation layer may be any suitable single layer or may be composed of multiple layers. Regarding the description of the retardation layer in Section C, unless otherwise specified, when simply referring to the "retardation layer," it means that the retardation layer is described as a whole.

[0040] The retardation layer 20 can typically have an in-plane retardation. Therefore, the retardation layer 20 typically has a relationship of nx>ny. The retardation layer exhibits any appropriate refractive index characteristics as long as it has the relationship of nx>ny. The refractive index characteristics of the retardation layer preferably exhibit the relationship of nx>ny≧nz. The Nz coefficient of the retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and even more preferably 0.9 to 1.2.

[0041] The retardation layer may be made of any suitable material as long as it has the above-described properties as a whole. As described above, the retardation layer may be a single layer or may have multiple layers. Also, as described above, the retardation layer may be a stretched film or a liquid crystal alignment solidified layer. The specific configuration of the retardation layer will be described below.

[0042] C-2. Stretched film In one embodiment, the retardation layer is a stretched film. In this case, the retardation layer is typically a single layer, and the stretched film constituting the single layer can function as a so-called λ / 4 plate. The in-plane retardation Re(550) of the stretched film is preferably 100 nm or more and 200 nm or less, more preferably 110 nm or more and 180 nm or less, even more preferably 120 nm or more and 160 nm or less, and particularly preferably 130 nm or more and 150 nm or less. The angle between the slow axis of the stretched film and the absorption axis of the polarizer is preferably 40° or more and 50° or less, more preferably 42° or more and 48° or less, and even more preferably 44° or more and 46° or less. The Re(650) / Re(550) of the stretched film is, for example, 1.0 or more and less than 1.15, preferably 1.02 or more and 1.13 or less, and more preferably 1.03 or more and 1.10 or less. The Re(450) / Re(550) is, for example, 0.7 or more and 0.95 or less, preferably 0.75 or more and 0.92 or less, and more preferably 0.8 or more and 0.9 or less.

[0043] The thickness of the stretched film may be, for example, 5 μm or more and 200 μm or less, preferably 10 μm or more and 70 μm or less, and more preferably 20 μm or more and 60 μm or less.

[0044] Any suitable resin film can be used as the stretched film as long as the retardation layer has the above-mentioned properties. Typical examples of the resin constituting the resin film include polycarbonate-based resins and polyester carbonate-based resins (hereinafter sometimes simply referred to as polycarbonate-based resins).

[0045] Any suitable polycarbonate resin can be used as the polycarbonate resin. For example, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of an alicyclic diol, an alicyclic dimethanol, di-, tri- or polyethylene glycol, and an alkylene glycol or spiroglycol.

[0046] Preferably, the polycarbonate-based resin contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, structural units derived from an alicyclic dimethanol, and / or structural units derived from di-, tri-, or polyethylene glycol; more preferably, it contains structural units derived from a fluorene-based dihydroxy compound, structural units derived from an isosorbide-based dihydroxy compound, and structural units derived from di-, tri-, or polyethylene glycol.

[0047] The polycarbonate resin may contain structural units derived from other dihydroxy compounds as necessary. The retardation layer can be formed by stretching a film composed of the above-mentioned polycarbonate resin under any appropriate stretching conditions. Details of the polycarbonate resin and the method of forming the retardation layer are described in, for example, JP 2014-10291 A, JP 2014-26266 A, JP 2015-212816 A, JP 2015-212817 A, JP 2015-212818 A, JP 2017-54093 A, and JP 2018-60014 A. The descriptions of these publications are incorporated herein by reference.

[0048] C-3. Liquid crystal alignment solidification layer In one embodiment, the retardation layer may be a liquid crystal alignment solidified layer. When the retardation layer is a liquid crystal alignment solidified layer, a desired in-plane retardation can be achieved with a thickness that is significantly thinner than that of a stretched resin film. As a result, the optical laminate can be significantly thinner. In the liquid crystal alignment solidified layer, rod-shaped liquid crystal compounds are typically aligned in the slow axis direction of the retardation layer (homogeneous alignment).

[0049] The retardation layer may be a single layer of a liquid crystal alignment solidified layer, or may be a laminated structure of two or more layers. In one embodiment, the retardation layer has a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer. The first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer may typically be laminated via an adhesive layer. In the following, when simply referring to a "liquid crystal alignment solidified layer," this means that the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer are collectively described.

[0050] The first liquid crystal alignment solidified layer can typically function as a λ / 2 plate, and the second liquid crystal alignment solidified layer can typically function as a λ / 4 plate. As a result, the liquid crystal alignment solidified layer (a two-layer structure of the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer) can function as a λ / 4 plate as a retardation layer as a whole. As a result, the retardation layer as a whole has a circular polarization function and an elliptically polarization function. The Re(550) of the first liquid crystal alignment solidified layer is preferably 200 nm or more and 300 nm or less, more preferably 220 nm or more and 290 nm or less, and even more preferably 260 nm or more and 280 nm or less; the Re(550) of the second liquid crystal alignment solidified layer is preferably 100 nm or more and 200 nm or less, more preferably 110 nm or more and 180 nm or less, and even more preferably 130 nm or more and 150 nm or less. Both the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer have in-plane retardation and therefore exhibit a refractive index characteristic of nx>ny. The first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer typically exhibit a refractive index characteristic of nx>ny=nz (positive A plate). The Nz coefficients of the first liquid crystal alignment solidified layer and the second liquid crystal alignment solidified layer may each be 0.9 to 1.1.

[0051] As described above, the angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 10° or more and 20° or less, more preferably 12° or more and 18° or less, and even more preferably 14° or more and 16° or less; the angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 70° or more and 80° or less, more preferably 72° or more and 78° or less, and even more preferably 74° or more and 76° or less. The direction of the slow axis of the first liquid crystal alignment solidified layer can be controlled by an alignment treatment. Note that the angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer and the angle between the slow axis of the second liquid crystal alignment solidified layer and the absorption axis of the polarizer may be reversed.

[0052] The thickness of the liquid crystal alignment solidified layer can be adjusted to obtain the desired in-plane retardation. The thickness of the first liquid crystal alignment solidified layer can be, for example, 1.5 μm to 2.5 μm. With this configuration, the thickness of the first liquid crystal alignment solidified layer can be thinner than conventional layers. The thickness of the second liquid crystal alignment solidified layer can also be adjusted to obtain the desired in-plane retardation. Specifically, the thickness can be, for example, 0.8 μm to 1.5 μm.

[0053] The liquid crystal alignment solidified layer can be formed, for example, on any suitable substrate. Specifically, the liquid crystal alignment solidified layer can be formed by performing an alignment treatment on the surface of the substrate, applying a coating liquid containing a liquid crystal compound to the surface, aligning the liquid crystal compound in a direction corresponding to the alignment treatment, and fixing the alignment state. The substrate can be any suitable resin film. Preferably, a triacetyl cellulose (TAC) film can be used as the substrate.

[0054] As described above, by using a liquid crystal compound, the difference between nx and ny of the resulting liquid crystal alignment solidified layer can be made significantly larger than that of a non-liquid crystal material, and the thickness of the liquid crystal alignment solidified layer to obtain a desired in-plane retardation can be made significantly smaller, resulting in a thinner and lighter optical laminate.

[0055] Any appropriate alignment treatment can be adopted as the alignment treatment. Specific examples include mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment. Specific examples of mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique deposition and photoalignment treatment. Any appropriate treatment conditions can be adopted for the various alignment treatments depending on the purpose.

[0056] The alignment of the liquid crystal compound is achieved by treating the liquid crystal compound at a temperature at which the liquid crystal compound exhibits liquid crystallinity depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state and aligns in accordance with the alignment treatment direction of the substrate surface.

[0057] In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

[0058] Examples of liquid crystal compounds used in the liquid crystal alignment solidified layer include liquid crystal polymers and liquid crystal monomers. The liquid crystal compound is preferably polymerizable (i.e., a liquid crystal monomer). If the liquid crystal compound is polymerizable, the alignment state of the liquid crystal compound can be fixed by aligning the liquid crystal compound and then polymerizing it. Here, the polymer formed by polymerization is non-liquid crystal. Therefore, the formed liquid crystal alignment solidified layer does not undergo, for example, a transition to a liquid crystal phase, glass phase, or crystalline phase due to temperature changes, which is unique to liquid crystal compounds. As a result, the liquid crystal alignment solidified layer becomes a retardation layer that is not affected by temperature changes and has extremely excellent stability.

[0059] The liquid crystal alignment solidified layer can be formed, for example, using a composition containing any suitable polymerizable liquid crystal compound (polymerizable liquid crystal compound, i.e., liquid crystal monomer). In this specification, the polymerizable liquid crystal compound contained in the composition refers to a compound having a polymerizable group and liquid crystallinity. The polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical or acid generated from a photopolymerization initiator. Examples of liquid crystal monomers that can be used include polymerizable mesogen compounds described in JP-A-2002-533742 (WO 00 / 37585), EP 358208 (US 5,211,877), EP 66137 (US 4,388,453), WO 93 / 22397, EP 0261712, DE 19504224, DE 4408171, and GB 2280445. Specific examples of such polymerizable mesogenic compounds include LC242 (trade name) from BASF, E7 (trade name) from Merck, and LC-Sillicon-CC3767 (trade name) from Wacker-Chem.

[0060] The mechanism by which the liquid crystal compound exhibits liquid crystallinity may be thermotropic or lyotropic. The liquid crystal phase may be nematic or smectic. From the viewpoint of ease of production, the liquid crystallinity is preferably thermotropic nematic liquid crystal.

[0061] The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type of the liquid crystal monomer. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and particularly preferably 60°C to 90°C.

[0062] In another embodiment, the retardation layer may be a single layer of a liquid crystal alignment solidified layer. A single layer of a liquid crystal alignment solidified layer may typically function as a λ / 4 plate. A single layer of a liquid crystal alignment solidified layer may typically have reverse dispersion wavelength characteristics. With such a configuration, the optical laminate may have very excellent antireflection performance. The preferred optical characteristics of the single layer of a liquid crystal alignment solidified layer may be similar to those of the stretched film described in Section C-2 above. The thickness of the single layer of a liquid crystal alignment solidified layer may typically be set to a thickness that allows it to properly function as a λ / 4 plate. The angle between the slow axis of the single layer of a liquid crystal alignment solidified layer and the absorption axis of the polarizer is preferably 40° or more and 50° or less, more preferably 42° or more and 48° or less, and even more preferably 44° or more and 46° or less.

[0063] D. Positive C plate The optical laminate may further include a layer having a refractive index characteristic that satisfies the relationship nz>nx=ny in addition to the retardation layer, as long as the object of the present invention can be achieved. A layer having a refractive index characteristic that satisfies the relationship nz>nx=ny is also called a positive C plate. The positive C plate can be disposed in, for example, the stretched film. The positive C plate can also be disposed in, for example, the liquid crystal alignment solidified layer. When the optical laminate includes a positive C plate, reflections in oblique directions can be more effectively prevented, enabling the anti-reflection function to have a wider viewing angle. Note that the positive C plate is not an essential component of the optical laminate.

[0064] The positive C plate has a thickness direction retardation Rth(550) of preferably −50 nm to −300 nm, more preferably −70 nm to −250 nm, still more preferably −90 nm to −200 nm, and particularly preferably −100 nm to −180 nm. The positive C plate may have an in-plane retardation Re(550) of less than 10 nm.

[0065] The positive C plate can be formed of any appropriate material. Preferably, the positive C plate is made of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the positive C plate include those described in paragraphs

[0020] to

[0028] of JP 2002-333642 A. In this case, the thickness of the positive C plate is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0066] E. Optical compensation layer As described above, the optical compensation layer has a refractive index characteristic that satisfies the relationship nx=ny>nz, and a thickness direction retardation Rth of 10 nm or more. That is, in one embodiment, the optical compensation layer can be a negative C plate having a thickness direction retardation Rth(550) of 10 nm or more. The relationship "nx=ny" has been described above. In one embodiment, the optical compensation layer may typically be interposed between the polarizer and the retardation layer. In the embodiment of the present invention, the term "optical compensation layer" refers to a layer that is interposed between the polarizer and the retardation layer and has a function (optical compensation function) that can improve and / or enhance the optical properties of the entire optical laminate. However, this does not mean that a layer with an optical compensation function may be disposed at a position other than the above-mentioned position in the optical laminate.

[0067] As described above, the Rth(550) of the optical compensation layer is typically 10 nm or more, preferably 15 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit of Rth(550) of the optical compensation layer is, for example, 50 nm.

[0068] When an optical compensation layer is provided, the average value b * Aveis preferably 0 or less, more preferably -1.0 or less, even more preferably -2.0 or less, particularly preferably -3.0 or less, and most preferably -4.0 or less. Within such a range, the effects of the present invention can be more pronounced.

[0069] The thickness of the optical compensation layer can be set to any appropriate thickness as long as it can have the above properties. The thickness of the optical compensation layer is, for example, 1 μm to 50 μm, preferably 1 μm to 30 μm, more preferably 2 μm to 25 μm, and even more preferably 3 μm to 20 μm.

[0070] The optical compensation layer can be made of any suitable material capable of forming a negative C plate within the scope of the present invention. A preferred material for forming the negative C plate is a TAC (triacetyl cellulose) resin. The material for forming the negative C plate may be, for example, a film mainly composed of polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, or polyamide.

[0071] F. Image display device The optical laminates described in the above items A to E can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such optical laminates. Representative examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the optical laminate described in the above items A to E on its viewing side. The optical laminate is arranged so that the side of the polarizing plate opposite to the retardation layer is the viewing side. [Example]

[0072] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Measurement and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0073] (1) Thickness The thickness was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., "MCPD9800"). (2) In-plane retardation Re(λ) and thickness retardation Rth(λ) The retardation of the retardation layer and the optical compensation layer used in the examples and comparative examples was measured using Axoscan (manufactured by Axometrics) at wavelengths of 450 nm, 550 nm and 650 nm, and at a temperature of 23°C. Furthermore, Re(450) / Re(550) and Re(650) / Re(550) were calculated as indices of wavelength dispersion characteristics. (3) Hue (b * Ave ) The optical laminates obtained in the examples and comparative examples were cut to a predetermined size to serve as samples for hue measurement, and these samples for hue measurement were left standing in an environment at a temperature of 95°C for 120 hours. After 120 hours, the reflective hue of the samples for hue measurement was measured from a polar angle of 60° using a display measurement system "DMS-505" manufactured by Konica Minolta. The measurement was carried out in the azimuth angle range of 0° to 180°, and the L at each of the azimuths of 0°, 45°, 90°, and 135° was measured. * a * b * Color space b * The average value was calculated based on these values, and b * Ave It was decided. (4) Color unevenness due to burn-in (4-1) Preparation of test samples The organic EL panel (image display panel) with the polarizing film attached was removed from an organic EL display (product name "Galaxy A41" manufactured by Samsung), the polarizing film was removed, and the removed surface was cleaned. Next, the optical laminates obtained in the examples and comparative examples were cut to a predetermined size, and the retardation layer side of the optical laminate was attached to the above-mentioned cleaned organic EL panel via an adhesive to prepare an image display device, which was used as a test sample. (4-2) Test evaluation The test sample was left in a lit state for 120 hours in an environment at a temperature of 95°C. After 120 hours had passed, the light was turned off and the test sample after the test was removed and its condition (color unevenness due to burn-in) was visually observed and evaluated according to the following criteria. A: Virtually no color unevenness due to image display panel burn-in was observed. B: Slight color unevenness due to burn-in of the image display panel was observed, but was within the range acceptable for practical use. C: Color unevenness due to burn-in of the image display panel was clearly observed, and was practically unacceptable.

[0074] [Production Example 1-1: Preparation of polarizing plate] A long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin made by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFFIMER") in a 9:1 ratio, to which 13 parts by weight of potassium iodide was added, in water. The above PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment). Next, the sample was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment). Thereafter, the film was dried in an oven maintained at about 90°C, and brought into contact with a heated roll made of SUS whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate, and a long laminate having a resin substrate / polarizer configuration was obtained. The polarizer had a single transmittance Ts of 43.3%. The polarizer had an absorption axis in the longitudinal direction. Hereinafter, the absorption axis direction (longitudinal direction) will be referred to as the "0° direction," and the transmission axis direction (width direction) will be referred to as the "90° direction."

[0075] An HC-TAC film was bonded to the polarizer surface (the surface opposite to the resin substrate) of the resulting laminate via a UV-curable adhesive. The HC-TAC film was a triacetyl cellulose resin (TAC) film (thickness: 25 μm) with an HC layer (thickness: 4 μm) formed thereon, and the TAC film was bonded to the polarizer side. Next, the resin substrate was peeled off, and an acrylic film (product name RX-30 (acrylic resin), manufactured by Toyo Kohan Co., Ltd., thickness: 30 μm, Rth (550): 0 nm) was bonded to the peeled surface via a UV-curable adhesive as a protective layer (inner protective layer). In this way, a polarizing plate P1 having a configuration of HC layer / TAC film / polarizer / acrylic film was obtained.

[0076] [Production Example 1-2: Preparation of polarizing plate] A polarizing plate P2 having a structure of HC layer / TAC film / polarizer was obtained in the same manner as in Production Example 1-1, except that the protective layer (inner protective layer) was not formed.

[0077] [Manufacturing Example 2-1: Preparation of Retardation Layer] (Preparation of stretched film) Polymerization was carried out using a batch polymerization apparatus consisting of two vertical stirred reactors equipped with a stirring blade and a reflux condenser. The polymerization mixture consisted of 30.31 parts by mass (0.047 mol) of BPFM, 39.94 parts by mass (0.273 mol) of ISB, 30.20 parts by mass (0.099 mol) of SPG, 69.67 parts by mass (0.325 mol) of DPC, and 7.88 × 10 calcium acetate monohydrate as a catalyst. -4 Part of mass (4.47×10 -6 mol) was charged. After the inside of the reactor was purged with nitrogen under reduced pressure, heating was performed using a heat medium, and stirring was started when the internal temperature reached 100°C. 40 minutes after the start of the temperature increase, the internal temperature reached 220°C, and while controlling to maintain this temperature, pressure reduction was started, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 220°C. Phenol vapor, a by-product of the polymerization reaction, was introduced into a reflux condenser at 110°C, and a small amount of monomer components contained in the phenol vapor was returned to the reactor. Uncondensed phenol vapor was collected by introducing nitrogen into the first reactor and temporarily restoring the pressure to atmospheric pressure. The oligomerized reaction liquid in the first reactor was then transferred to the second reactor. Next, the temperature and pressure in the second reactor were increased, and the internal temperature reached 240°C and the pressure reached 20 kPa in 40 minutes. The pressure was then further reduced, and polymerization was allowed to proceed until the specified stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the polyester carbonate produced was extruded into water, and the strands were cut to obtain pellets. The ratio of the structural units derived from each monomer was BPFM / ISB / SPG / DPC=21.5 / 39.4 / 30.0 / 9.1% by mass. The obtained polyester carbonate was extrusion-kneaded using Dianale BR80 (Mitsubishi Chemical Corporation) as the acrylic resin. A mixture of polycarbonate pellets (99.5 parts by mass) and BR80 powder (0.5 parts by mass) was fed into a twin-screw extruder TEX30HSS (Japan Steel Works, Ltd.) using a metering feeder. The extruder cylinder temperature was set to 250°C, and extrusion was carried out at a throughput of 12 kg / hr and a screw rotation speed of 120 rpm. The extruder was also equipped with a vacuum vent, and the molten resin was extruded while being devolatilized under reduced pressure. The resin composition pellets thus obtained were vacuum-dried at 100°C for 6 hours or more, and then a film-forming device equipped with a single-screw extruder (manufactured by Isuzu Chemical Engineering Co., Ltd., screw diameter 25mm, cylinder temperature setting: 250°C), a T-die (width: 300mm, temperature setting: 220°C), a chill roll (temperature setting: 120-130°C) and a winder was used to produce a long unstretched film having a length of 3m, a width of 200mm and a thickness of 100μm. This long unstretched film was stretched at a stretching temperature of Tg and a stretch ratio of 2.2 times to obtain a stretched film having a thickness of 47μm, which was used as the retardation layer R1. The retardation layer R1 thus obtained had a Re(550) of 131 nm, a Re(450) / Re(550) ratio of 0.85, and a Re(550) / Re(650) ratio of 1.06. The retardation layer R1 satisfied the relationship Re(650)>Re(550)>Re(450). [Compound abbreviation] The abbreviations for the compounds used in the above production examples are as follows. ISB: Isosorbide [Rocket Fleuret] SPG: Spiroglycol [Mitsubishi Gas Chemical Company, Inc.] DPC: Diphenyl carbonate [Mitsubishi Chemical Corporation] BPFM: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane [ka]

[0078] [Manufacturing Example 2-2: Preparation of Retardation Layer] A stretched film was produced in the same manner as in Production Example 2-1, except that the thickness of the stretched film was changed to 49 nm. The thickness of this long unstretched film was 105 nm, and the stretching conditions were a stretching temperature of Tg and a stretching ratio of 2.2 times. The obtained stretched film was used as retardation layer R2. The retardation layer R2 obtained had a Re(550) of 137 nm, a Re(450) / Re(550) ratio of 0.85, and a Re(550) / Re(650) ratio of 1.06. The retardation layer R2 satisfied the relationship Re(650)>Re(550)>Re(450).

[0079] [Production Example 2-3: Preparation of Retardation Layer] A stretched film was produced in the same manner as in Production Example 2-1, except that the thickness of the stretched film was changed to 51 nm. The thickness of the long unstretched film was 113 nm, and the stretching conditions were a stretching temperature of Tg and a stretching ratio of 2.3 times. The obtained stretched film was used as retardation layer R3. The retardation layer R3 thus obtained had a Re(550) of 142 nm, a Re(450) / Re(550) ratio of 0.85, and a Re(550) / Re(650) ratio of 1.06. The retardation layer R3 satisfied the relationship Re(650)>Re(550)>Re(450).

[0080] [Production Example 2-4: Preparation of retardation layer] A stretched film was produced in the same manner as in Production Example 2-1, except that the thickness of the stretched film was changed to 52 nm. The thickness of the long unstretched film was 125 nm, and the stretching conditions were a stretching temperature of Tg and a stretching ratio of 2.3 times. The obtained stretched film was used as retardation layer R4. The retardation layer R4 thus obtained had a Re(550) of 144 nm, a Re(450) / Re(550) ratio of 0.85, and a Re(550) / Re(650) ratio of 1.06. The retardation layer R4 satisfied the relationship Re(650)>Re(550)>Re(450).

[0081] [Manufacturing Example 2-5: Preparation of retardation layer] A stretched film was produced in the same manner as in Production Example 2-1, except that the thickness of the stretched film was changed to 51 nm. The thickness of the long unstretched film was 125 nm, and the stretching conditions were a stretching temperature of Tg and a stretching ratio of 2.3 times. The resulting stretched film was used as retardation layer R5. The resulting retardation layer R5 had an Re(550) of 142 nm, an Re(450) / Re(550) ratio of 0.85, and an Re(550) / Re(650) ratio of 1.06. The retardation layer R5 satisfied the relationship Re(650)>Re(550)>Re(450).

[0082] [Manufacturing Example 2-6: Preparation of retardation layer] (Preparation of the first liquid crystal alignment solidified layer) A liquid crystal composition (coating liquid) was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Irgacure 907") in 40 g of toluene. [ka] The surface of a polyethylene terephthalate (PET) film substrate (thickness: 38 μm) was rubbed with a rubbing cloth to perform an alignment treatment. The direction of the alignment treatment was set to be 15° from the viewing side with respect to the direction of the absorption axis of the polarizer when it was attached to the polarizing plate. The above liquid crystal coating solution was applied to this alignment-treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was then irradiated with 1 mJ / cm using a metal halide lamp. 2 The liquid crystal layer was cured by irradiating it with light, thereby forming a first liquid crystal alignment solidified layer L1 on the PET film substrate. The first liquid crystal alignment solidified layer L1 had a thickness of 2.5 μm and an in-plane retardation Re(550) of 270 nm. Furthermore, the first liquid crystal alignment solidified layer L1 had a refractive index distribution of nx>ny=nz. (Preparation of second liquid crystal alignment solidified layer) A second liquid crystal alignment layer L2 was formed on a PET film substrate in the same manner as above, except that the coating thickness was changed and the alignment treatment direction was set to a 75° angle relative to the absorption axis of the polarizer when viewed from the viewing side. The second liquid crystal alignment layer L2 had a thickness of 1.5 μm and an in-plane retardation Re(550) of 140 nm. Furthermore, the second liquid crystal alignment layer L2 had a refractive index distribution of nx>ny=nz. (Preparation of Retardation Layer) The surface of the second liquid crystal alignment layer L2 (the side opposite the PET film substrate) was bonded to the surface of the first liquid crystal alignment layer L1 (the side opposite the PET film substrate) via an active energy ray-curable adhesive (thickness: 1 μm), thereby obtaining a laminate having a structure of substrate / first liquid crystal alignment layer L1 / adhesive layer / second liquid crystal alignment layer L2 / substrate. The outermost substrate was peeled off from this laminate to obtain a retardation layer R6. The bonding and peeling were performed using a roll-to-roll process.

[0083] [Manufacturing Example 2-7: Preparation of retardation layer] (Preparation of reverse dispersion liquid crystal film) 55 parts of a compound represented by formula (I), 25 parts of a compound represented by formula (II), and 20 parts of a compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN), heated to 60°C, and stirred to dissolve. After dissolution was confirmed, the mixture was returned to room temperature, and 3 parts of Irgacure 907 (manufactured by BASF Japan Ltd.), 0.2 parts of Megafac F-554 (manufactured by DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added and further stirred to obtain a solution. The solution was transparent and homogeneous. The resulting solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. Separately, a polyimide solution for an alignment film was applied to a 0.7 mm-thick glass substrate using a spin coating method, dried at 100°C for 10 minutes, and then baked at 200°C for 60 minutes to obtain a coating film. The resulting coating film was subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to a substrate (substantially an alignment film) by spin coating and dried for 2 minutes at 100° C. After the obtained coating film was cooled to room temperature, it was irradiated with 30 mW / cm using a high-pressure mercury lamp.2 The liquid crystal alignment layer L3 was obtained by irradiating it with ultraviolet light at an intensity of 1000 nm for 30 seconds. The in-plane retardation Re(550) of the liquid crystal alignment layer L3 was 130 nm. The Re(450) / Re(550) of the liquid crystal alignment layer L3 was 0.851, and it exhibited reverse dispersion wavelength characteristics. This liquid crystal alignment layer L3 was used as the retardation layer R7. [ka] [ka]

[0084] [Manufacturing Example 2-8: Preparation of retardation layer] A retardation layer was prepared in the same manner as in Production Example 2-6, except that the adhesive layer was replaced with a high-refractive-index adhesive (thickness: 6.0 μm). Specifically, the adhesive was disposed on the first liquid crystal alignment solidified layer L1 of a laminate of a first liquid crystal alignment solidified layer L1 / substrate. Subsequently, the second liquid crystal alignment solidified layer L2 of a laminate of a second liquid crystal alignment solidified layer L2 / substrate was disposed so that the second liquid crystal alignment solidified layer L2 overlapped the adhesive layer. In this manner, a laminate having a structure of substrate / first liquid crystal alignment solidified layer L1 / adhesive layer (high-refractive-index adhesive layer) / second liquid crystal alignment solidified layer L2 / substrate was obtained. The outermost substrate was peeled from this laminate to obtain a retardation layer R8. The Re(550) of the obtained retardation layer R8 was 140 nm. The adhesive having a high refractive index was an acrylic adhesive composition (1) prepared using an acrylic polymer prepared by the following method. <Preparation of acrylic pressure-sensitive adhesive composition (1)> A four-neck flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser was charged with 85 parts by weight of phenoxybenzyl acrylate (POB-A), 2 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 13 parts by weight of n-butyl acrylate (BA). Next, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator and ethyl acetate were added to 100 parts by weight of the mixture (monomer mixture). Nitrogen gas was introduced and replaced with nitrogen while gently stirring. The mixture was stirred for 7 hours while maintaining the liquid temperature in the flask at around 55°C. The monomer concentration during stirring was adjusted to 40% by weight. Ethyl acetate was then added to the resulting reaction solution to adjust the solids concentration to 30%. This yielded an acrylic polymer solution. The POB-A used was a commercially available monomer (Kyoeisha Chemical Co., Ltd., purity 94%) that had been further purified by adsorption. To 100 parts by weight of the solid content of the acrylic polymer, 0.3 parts by weight of an isocyanate crosslinking agent (trimethylolpropane / xylylene diisocyanate trimer adduct, Mitsui Chemicals, Takenate D-110N) was added, and ethyl acetate was added as a dilution solvent so that the total solid content was 15% by weight, followed by mixing and stirring. In this way, an acrylic pressure-sensitive adhesive composition (1) was prepared.

[0085] [Manufacturing Example 2-9: Preparation of retardation layer] A retardation layer was produced in the same manner as in Production Example 2-5, except that the adhesive layer was changed to an adhesive having a high refractive index (thickness: 1.0 μm). In this way, a retardation layer R9 having a structure of first liquid crystal alignment solidified layer L1 / adhesive layer (high refractive adhesive layer) / second liquid crystal alignment solidified layer L2 was obtained. The Re(550) of the obtained retardation layer R9 was 140 nm. The adhesive having a high refractive index was prepared by preparing an adhesive composition as follows. <Preparation of Adhesive Composition> (i) 50 wt% metal oxide particles, (ii) curable components (28.5 wt% curable component 1, 8 wt% curable component 2, 1 wt% curable component 3, and 7 wt% curable component 4), (iii) 0.5 wt% leveling agent, and (iv) photopolymerization initiators (1 wt% initiator 1, 2 wt% initiator 2, and 2 wt% initiator 3) were mixed and stirred at 50°C for 1 hour to prepare an adhesive composition. The weight proportion of each component is the proportion (wt%) when the total solid content of the adhesive composition is taken as 100 wt%. Details of components (i) to (iv) are as follows: (i) Metal oxide particles Zirconia dispersion (a dispersion of zirconium oxide with an average particle size of 8 nm dispersed in phenoxybenzyl acrylate (particle component concentration 50% by weight) (ii) Curable component Curing component 1: (meth)acrylate with an aromatic ring skeleton: phenoxybenzyl acrylate (product name "Light Acrylate POB-A" manufactured by Kyoeisha Chemical Co., Ltd.) Curing component 2: Hydroxyl group-containing (meth)acrylate (Mitsubishi Chemical Corporation product name "4HBA" (4-hydroxybutyl acrylate)) Curing component 3: 3-methacrylamidophenylboronic acid (product name "MAPBA" manufactured by Junsei Chemical Co., Ltd.) Curing component 4: Multifunctional radical polymerizable compound (triplypropylene glycol diacrylate, product name "Aronix M-220" manufactured by Toagosei Co., Ltd.) (iii) Leveling agent BYK UV-3505 (a leveling agent containing a modified isocyanurate compound with a (meth)acryloyl group and a modified polysiloxane compound with a (meth)acryloyl group) (iv) Photopolymerization initiator Initiator 1: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (product name "Omnirad 819" manufactured by IGM Resins BV) Initiator 2: 1-hydroxycyclohexyl phenyl ketone (product name "Omnirad 184" manufactured by IGM Resins BV) Initiator 3: Diethylthioxanthone (trade name "KAYACURE DETX-S" manufactured by Nippon Kayaku Co., Ltd.)

[0086] [Manufacturing example 3-1: Optical compensation layer] As the optical compensation layer, a cellulose acylate film (trade name "TK25SL" manufactured by Fujifilm Corporation, thickness: 26 μm) having refractive index characteristics satisfying the relationship nx=ny>nz was prepared. The retardation Rth in the thickness direction of the optical compensation layer was 15 nm.

[0087] [Production example 3-2: Optical compensation layer] As the optical compensation layer, a cellulose acylate film (manufactured by Fujifilm Corporation under the trade name "TG60UL", thickness: 60 μm) having a refractive index characteristic satisfying the relationship nx=ny>nz was prepared. The retardation Rth(550) in the thickness direction of the optical compensation layer was 34 nm.

[0088] [Production example 3-3: Optical compensation layer] As the optical compensation layer, a cellulose acylate film (manufactured by Fujifilm Corporation under the trade name Fujitac "TG40UL", thickness: 40 μm) having refractive index characteristics satisfying the relationship nx=ny>nz was prepared. The retardation Rth in the thickness direction of the optical compensation layer was 30 nm.

[0089] [Production Example 3-4: Comparative optical compensation layer] As an optical compensation layer, a cellulose acylate film (manufactured by Fujifilm Corporation under the trade name "0 TAC", thickness: 60 μm) having refractive index characteristics satisfying the relationship nx=ny=nz was prepared. The retardation Rth in the thickness direction of the optical compensation layer was 0 nm.

[0090] [Production example 3-5: Optical compensation layer] As the optical compensation layer, a cellulose acylate film (thickness: 25 μm) manufactured by Fujifilm Corporation under the trade name "TJ25" and having a refractive index characteristic satisfying the relationship nx=ny>nz was prepared. The retardation Rth of the optical compensation layer in the thickness direction was 9 nm.

[0091] [Manufacturing Example 4: Preparation of positive C-plate] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer of the following chemical formula (n = 0.35, shown as a block polymer for convenience), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: Paliocolor LC242 product name), and 5 parts by weight of a photopolymerization initiator (BASF: Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a PET substrate that had been subjected to a vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. The liquid crystal layer was irradiated with ultraviolet light to harden it, resulting in a long laminate having a substrate / positive C-plate C1 (thickness: 1.0 μm) configuration. [ka]

[0092] [Example 1] (Production of optical laminate) The substrate / positive C-plate C1 (thickness: 1.0 μm) of Production Example 4 was transferred onto the surface of the retardation layer R1 made of the stretched film of Production Example 2-1 via an acrylic adhesive (thickness: 1.0 μm), thereby obtaining a laminate having a configuration of retardation layer R1 (stretched film) / adhesive layer / positive C-plate C1. Next, the retardation layer R1 of the laminate obtained above was attached to the TAC film (inner protective layer) side of the polarizing plate P1 of Production Example 1-1 via an acrylic adhesive (thickness: 20 μm). At this time, it was attached so that the slow axis direction of the retardation layer R1 was at an angle of 45° with respect to the absorption axis direction of the polarizer. In this way, an optical laminate having a configuration of polarizing plate (HC layer / TAC film / polarizer / acrylic film) / adhesive layer / retardation layer (stretched film) / adhesive layer / positive C plate was obtained. The obtained optical laminate was subjected to the measurement of the hue in (3) above. * Ave The optical laminate obtained was subjected to the evaluation in (4) above. The results are shown in Table 1.

[0093] [Examples 2 to 4 and Comparative Example 1] An optical laminate was produced in the same manner as in Example 1, except that the retardation layer was changed to that of the manufacturing example shown in Table 1. In Comparative Example 1, the first liquid crystal alignment solidified layer L1 side of the retardation layer R6 was attached to the TAC film (inner protective layer) side of the polarizing plate P1. The obtained optical laminate was subjected to the hue measurement (3) above and the evaluation (4) above. The results are shown in Table 1.

[0094] [Example 5] (Production of optical laminate) The substrate was peeled off from the first liquid crystal alignment solidified layer L1 of the retardation layer R6 of Manufacturing Example 2-6, and the optical compensation layer (negative C plate) of Manufacturing Example 3-1 was bonded to the surface of the first liquid crystal alignment solidified layer L1 via an acrylic adhesive (thickness: 5 μm), thereby obtaining a laminate (laminate with an optical compensation layer) having a configuration of optical compensation layer (negative C plate) / adhesive layer / first liquid crystal alignment solidified layer L1 / adhesive layer / second liquid crystal alignment solidified layer L2 / substrate. Next, the surface (optical compensation layer side) of the laminate was bonded to the polarizer surface of the polarizing plate P2 of Production Example 1-2 via an acrylic adhesive (thickness: 5 μm). Next, the substrate of the second liquid crystal alignment solidified layer L2 was peeled off. In this way, an optical laminate having a structure of polarizing plate (HC layer / TAC film / polarizer) / adhesive layer / optical compensation layer (negative C plate) / adhesive layer / retardation layer (first liquid crystal alignment solidified layer / adhesive layer (adhesive layer) / second liquid crystal alignment solidified layer) was obtained. Note that the bonding and peeling were performed by a roll-to-roll process. In addition, when bonding the retardation layer, the angle between the absorption axis direction of the polarizer and the slow axis direction of the first liquid crystal alignment solidified layer was 15°, and the angle between the absorption axis direction of the polarizer and the slow axis direction of the second liquid crystal alignment solidified layer was 75°. The obtained optical laminate was subjected to the measurement of the hue described above in (3). b of the optical laminate * Ave The value was 0. The optical layered body thus obtained was also subjected to the evaluation in (4) above. The results are shown in Table 1.

[0095] [Examples 6, 9, 10 and Comparative Examples 2 to 3] (Production of optical laminate) An optical laminate was produced in the same manner as in Example 5, except that the retardation layer and / or the optical compensation layer were changed to those of the production examples shown in Table 1. The obtained optical laminate was subjected to the measurement of hue in (3) above and the evaluation in (4) above. The results are shown in Table 1.

[0096] [Example 7] (Production of optical laminate) The positive C plate C1 of Production Example 4 was transferred onto the surface of the retardation layer R5 of Production Example 2-5 via an ultraviolet-curable adhesive (thickness: 1.0 μm) to bond it to the surface. In this way, a laminate having a configuration of retardation layer R5 (stretched film) / adhesive layer / positive C plate was obtained. Next, the optical compensation layer (negative C plate) of Production Example 3-1 was bonded to the surface (stretched film side) of the retardation layer R5 of the above laminate via an acrylic adhesive (thickness: 5 μm), thereby obtaining a laminate (laminate with an optical compensation layer) having a configuration of optical compensation layer (negative C plate) / adhesive layer / stretched film / adhesive layer / positive C plate. Next, a polarizing plate was attached to the laminate in the same manner as in Example 5, except that the laminate provided with the optical compensation layer was changed to the one obtained above. In this way, an optical laminate having a configuration of polarizing plate (HC layer / TAC film / polarizer) / adhesive layer / optical compensation layer (negative C plate) / adhesive layer / retardation layer (stretched film) / adhesive layer / positive C plate was obtained. The obtained optical laminate was subjected to the hue measurement (3) above and the evaluation (4) above. The results are shown in Table 1.

[0097] [Example 8] (Production of optical laminate) A laminate (a laminate including an optical compensation layer) was obtained in the same manner as in Example 7, except that the retardation layer was changed to that of the manufacturing example shown in Table 1, and an optical laminate was produced in the same manner as in Example 7, except that the laminate including the optical compensation layer was changed to that obtained above. The obtained optical laminate was subjected to the measurement of hue in (3) above and the evaluation in (4) above. The results are shown in Table 1.

[0098] [Table 1] [Industrial Applicability]

[0099] The optical laminate according to the embodiment of the present invention can be suitably used in image display devices (typically, liquid crystal display devices and organic EL display devices). [Explanation of symbols]

[0100] 10 Polarizing plate 11 Polarizer 12 Protective layer (1st protective layer) 13 Protective layer (second protective layer) 20 Retardation layer 30 Optical compensation layer (negative C plate) 100,101 Optical laminate

Claims

1. An optical laminate comprising a polarizing plate including a polarizer and a retardation layer, the retardation layer has a circular polarization function or an elliptically polarization function, After the optical laminate was left in an environment at a temperature of 95°C for 120 hours, the hue b at azimuth angles of 0°, 45°, 90° and 135° as viewed from a polar angle of 60° was measured. ＊ The average value of b ＊ Ａｖｅ is less than 1, Optical laminate.

2. the retardation layer has an in-plane retardation Re(550) of 100 nm or more and 200 nm or less, the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is 40° or more and 50° or less, and the retardation layer satisfies the relationship Re(650)>Re(550)>Re(450); The optical laminate according to claim 1 .

3. the retardation layer has a first liquid crystal alignment solidified layer and a second liquid crystal alignment solidified layer, the first liquid crystal alignment solidified layer has an in-plane retardation Re(550) of 200 nm or more and 300 nm or less, and the angle between the slow axis of the first liquid crystal alignment solidified layer and the absorption axis of the polarizer is 10° to 20°; The in-plane retardation Re(550) of the second liquid crystal alignment solidified layer is 100 nm or more and 200 nm or less, and the angle between the slow axis and the absorption axis of the polarizer is 70 ° to 80 °.

4. The optical laminate according to claim 2 , wherein the retardation layer is a stretched film.

5. 2. The optical laminate according to claim 1, further comprising an optical compensation layer between the polarizing plate and the retardation layer, the optical compensation layer having a refractive index characteristic of nx = ny > nz, and a retardation Rth(550) in the thickness direction of the optical compensation layer being 10 nm or more.

6. After the optical laminate was left in an environment at a temperature of 95°C for 120 hours, the hue b at azimuth angles of 0°, 45°, 90° and 135° as viewed from a polar angle of 60° was measured. ＊ The average value of b ＊ Ａｖｅ The optical laminate according to claim 5, wherein is 0 or less.

7. The optical laminate according to any one of claims 1 to 6 is provided. Image display device.

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