Polarizing plate equipped with retardation layer and adhesive layer, and image display device using polarizing plate equipped with the retardation layer and adhesive layer

Abstract

To provide a polarization plate having a retardation layer and an adhesive layer, capable of realizing an image display device in which phase difference unevenness is suppressed under a high temperature environment and color unevenness and leak light are suppressed under a high temperature environment.SOLUTION: A polarization plate having a retardation layer and an adhesive layer according to the present invention includes: a polarization plate including a polarizer; a retardation layer bonded to the polarization plate interposing a first adhesive layer; and a second adhesive layer provided as an outermost layer on a side opposite to the polarization plate of the retardation layer. The retardation layer is composed of an oriented film of a resin film and satisfies a relation of Re(450)<Re(550). A glue deviation amount of the first adhesive layer after a heating test at 85°C for 500 hours is 900 μm or less. A creep value of the second adhesive layer at 85°C is 40 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a retardation layer and a pressure-sensitive adhesive layer, and an image display device using the retardation layer and the polarizing plate with a pressure-sensitive adhesive layer. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal display devices and electroluminescence (EL) display devices (e.g., organic EL display devices and inorganic EL display devices), have rapidly become widespread. Image display devices typically use a polarizing plate and a retardation plate. In practice, retardation layer-attached polarizing plates, which integrate a polarizing plate and a retardation plate, are widely used (e.g., Patent Document 1). However, retardation layer-attached polarizing plates can develop unevenness in retardation under high-temperature conditions, which can result in color unevenness and light leakage in image display devices under high-temperature conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3325560 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 a retardation layer and a polarizing plate with a pressure-sensitive adhesive layer that can realize an image display device in which retardation unevenness is suppressed in a high-temperature environment and color unevenness and light leakage are suppressed in a high-temperature environment. [Means for solving the problem]

[0005] The retardation layer and the polarizing plate with an adhesive layer according to an embodiment of the present invention include a polarizing plate containing a polarizer, a retardation layer bonded to the polarizing plate via a first adhesive layer, and a second adhesive layer provided as an outermost layer on the side of the retardation layer opposite to the polarizing plate. The retardation layer is composed of a stretched film of a resin film and satisfies the relationship Re(450) < Re(550). The amount of adhesive spread after a heat test of the first adhesive layer at 85°C for 500 hours is 900 μm or less, and the creep value of the second adhesive layer at 85°C is 40 μm or less. Here, Re(450) and Re(550) are the in-plane retardations measured with light having wavelengths of 450 nm and 550 nm at 23°C, respectively. In one embodiment, Re(550) of the retardation layer is 100 nm to 200 nm, and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50° or 130° to 140°. In one embodiment, the thickness of the retardation layer is 15 μm to 60 μm. In one embodiment, the amount of adhesive spread after a heat test of the first adhesive layer at 85°C for 500 hours is 250 μm or less. In one embodiment, the adhesive composition constituting the second adhesive layer contains 1.5 parts by weight or more of a crosslinking agent with respect to 100 parts by weight of a base polymer. In one embodiment, the adhesive composition constituting the second adhesive layer contains 5 parts by weight or more of a crosslinking agent with respect to 100 parts by weight of a base polymer. In one embodiment, the retardation layer and the polarizing plate with an adhesive layer further have another retardation layer having a refractive index characteristic showing a relationship of nz > nx = ny between the retardation layer and the second adhesive layer. In one embodiment, the retardation layer contains: a resin having positive refractive index anisotropy, which contains at least one bonding group selected from the group consisting of a carbonate bond and an ester bond, and at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2); and an acrylic resin; wherein the content of the acrylic resin is 0.5% by mass to 2.0% by mass, the acrylic resin contains 70% by mass or more of structural units derived from methyl methacrylate, and the weight average molecular weight Mw is 10,000 to 200,000: [ka] [ka] In general formulas (1) and (2), R 1 ~R 3 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group; with the proviso that R 4 ~R 9 may be the same or different, and R 4 ~R 9 At least two adjacent groups among these may be bonded to each other to form a ring. In one embodiment, the retardation layer has a dimensional change rate in the slow axis direction of 0.28% or less in a humidified TMA test in which the environment is changed in the order of 25°C / 50% RH, 60°C / 50% RH, and 60°C / 85% RH. In one embodiment, the retardation layer, with the other retardation layer bonded thereto, exhibits a dimensional change rate in the slow axis direction of 0.28% or less in a humidified TMA test in which the environment is changed in the order of 25°C / 50% RH, 60°C / 50% RH, and 60°C / 85% RH. According to another aspect of the present invention, there is provided an image display device, which includes the above-mentioned retardation layer and a pressure-sensitive adhesive layer-attached polarizing plate. [Effects of the Invention]

[0006] According to an embodiment of the present invention, in a retardation layer and a polarizing plate with a pressure-sensitive adhesive layer, by optimizing the adhesive slippage amount between the polarizer and the retardation layer and the creep value of the pressure-sensitive adhesive layer for bonding the retardation layer and the pressure-sensitive adhesive layer to an image display cell, it is possible to realize a retardation layer and a polarizing plate with a pressure-sensitive adhesive layer in which retardation unevenness is suppressed in a high-temperature environment, and as a result, it is possible to realize an image display device in which color unevenness and light leakage are suppressed in a high-temperature environment. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer and a pressure-sensitive adhesive layer according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] (Definition of terms and symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation of a film measured with light of wavelength λ nm at 23°C. For example, "Re(450)" is the in-plane retardation of a film measured with light of wavelength 450 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(450)" is the retardation in the thickness direction of a film measured with light of wavelength 450 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.

[0010] A. Overall structure of polarizing plate with retardation layer and adhesive layer Figure 1 is a schematic cross-sectional view of a retardation layer and a polarizing plate with an adhesive layer according to one embodiment of the present invention. The retardation layer and the polarizing plate 100 with an adhesive layer in the illustrated example include a polarizing plate 10, a retardation layer 30 bonded to the polarizing plate 10 via a first adhesive layer 20, and a second adhesive layer 40 provided as an outermost layer on the side opposite to the polarizing plate 10 of the retardation layer 30. The second adhesive layer 40 enables the retardation layer and the polarizing plate with an adhesive layer to be attached to an image display cell. The polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11, and a second protective layer 13 disposed on the other side of the polarizer 11. Depending on the purpose, one of the first protective layer 12 and the second protective layer 13 may be omitted. For example, since the retardation layer 30 can also function as a protective layer for the polarizer 11, the second protective layer 13 may be omitted. The angle formed by the slow axis of the retardation layer 30 and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, still more preferably 44° to 46°, and particularly preferably about 45°; alternatively, it is preferably 130° to 140°, more preferably 132° to 138°, still more preferably 134° to 136°, and particularly preferably about 135°.

[0011] The retardation layer 30 is composed of a stretched film of a resin film and satisfies the relationship of Re(450) < Re(550). The Re(550) of the retardation layer 30 is typically 100 nm to 200 nm. The amount of adhesive displacement after a heating test of 85°C and 500 hours of the first adhesive layer 20 is 900 μm or less, and the creep value of the second adhesive layer 40 at 85°C is 40 μm or less. Details of each layer constituting the retardation layer and the polarizing plate with an adhesive layer will be described later.

[0012] In one embodiment, the retardation layer and the polarizing plate with an adhesive layer may further have another retardation layer (not shown) between the retardation layer 30 and the second adhesive layer 40. Another retardation layer typically exhibits a refractive index characteristic of nz > nx = ny. By providing such another retardation layer, reflection in the oblique direction can be effectively prevented, and the anti-reflection function can be widened to a wider viewing angle.

[0013] In one embodiment, the retardation layer and the adhesive layer-attached polarizing plate may further include a conductive layer or an isotropic substrate with a conductive layer (not shown). When a conductive layer or an isotropic substrate with a conductive layer is provided, the retardation layer and the adhesive layer-attached polarizing plate can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between an image display cell (e.g., an organic EL cell) and a polarizing plate. The conductive layer or the isotropic substrate with a conductive layer is typically provided between the retardation layer 30 and the second adhesive layer 40. When another retardation layer is provided, the other retardation layer and the conductive layer or the isotropic substrate with a conductive layer are typically provided in this order from the retardation layer 30 side.

[0014] The retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate may have an additional retardation layer (not shown). The additional retardation layer may be provided in combination with another retardation layer, or may be provided alone (i.e., without providing another retardation layer). The optical properties (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the additional retardation layer may be appropriately set depending on the purpose.

[0015] The retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate may be in a sheet form or a long shape. In this specification, "long" means a long and narrow shape whose length is sufficiently longer than its width, and includes, for example, a long and narrow shape whose length is 10 times or more, preferably 20 times or more, its width. The long retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate can be wound into a roll.

[0016] Practically, it is preferable that a release film be temporarily attached to the surface of the second pressure-sensitive adhesive layer 40 until the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate are used. By temporarily attaching the release film, the second pressure-sensitive adhesive layer is protected and the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate can be formed into a roll.

[0017] The components of the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate will be described below.

[0018] B. Polarizer Any appropriate polarizer can be adopted as the polarizer 11. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

[0019] Specific examples of polarizers made of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (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, as well as polyene-based oriented films such as dehydrated PVA films and dehydrochlorinated polyvinyl chloride films. Polarizers obtained by dyeing a PVA film with iodine and uniaxially stretching it are preferred because of their excellent optical properties.

[0020] 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.

[0021] 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, stretching typically involves immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching can optionally further include in-air stretching the laminate at an elevated temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. 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 the resin substrate may be peeled off from the resin substrate / polarizer laminate and any appropriate protective layer depending on the purpose may be laminated on the peeled surface. Details of such polarizer manufacturing methods are described in, for example, JP 2012-73580 A and Japanese Patent No. 6470455 A. The descriptions of these patent documents are incorporated herein by reference.

[0022] The polarizer is preferably composed of a single-layer resin film. With such a configuration, a retardation layer and a polarizing plate with a pressure-sensitive adhesive layer can be obtained in which retardation unevenness in a high-temperature environment is suppressed due to a synergistic effect with the optimization of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

[0023] The thickness of the polarizer is preferably 15 μm or less, more preferably 1 μm to 12 μm, and even more preferably 3 μm to 12 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed and good durability of appearance during heating can be obtained. Furthermore, the thickness of the polarizer is particularly preferably 8 μm or less. When the thickness of the polarizer is equal to or less than this upper limit, peeling of the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate from the adherend and generation of bubbles in the pressure-sensitive adhesive layer can be suppressed in a high-humidity environment.

[0024] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. 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.

[0025] C. Protective layer The first protective layer 12 and the second protective layer 13 are each formed of any appropriate film that can be used as a protective layer for a polarizer. Specific examples of materials that can be the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones. Other examples include glassy polymers such as siloxane polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups in its side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups in its side chains, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0026] As described below, the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate are typically disposed on the viewing side of the image display device, and the first protective layer 12 is typically disposed on the viewing side. Therefore, the first protective layer 12 may be subjected to a surface treatment such as a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, or an anti-glare treatment, as needed. Furthermore / alternatively, the first protective layer 12 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, by imparting an (elliptical) polarization function or an ultra-high retardation), as needed. 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 retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate can be suitably applied to image display devices that can be used outdoors.

[0027] The thickness of the first protective layer is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. If a surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

[0028] In one embodiment, the second protective layer 13 is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm and the retardation Rth(550) in the thickness direction is -10 nm to +10 nm.

[0029] D. Retardation layer D-1. Characteristics of the retardation layer As described above, the in-plane retardation Re(550) of the retardation layer is 100 nm to 200 nm, preferably 110 nm to 180 nm, more preferably 120 nm to 160 nm, and further preferably 130 nm to 150 nm. That is, the retardation layer can function as a so-called λ / 4 plate.

[0030] The retardation layer satisfies the relationship of Re(450) < Re(550) as described above, and preferably further satisfies the relationship of Re(550) < Re(650). That is, the retardation layer exhibits an inverse dispersion wavelength dependence in which the retardation value increases according to the wavelength of the measurement light. Re(450) / Re(550) of the retardation film is, for example, more than 0.5 and less than 1.0, preferably 0.7 to 0.95, more preferably 0.75 to 0.92, and still more preferably 0.8 to 0.9. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

[0031] Since the retardation layer has an in-plane retardation as described above, it has a relationship of nx > ny. As long as the retardation layer has a relationship of nx > ny, it exhibits any appropriate refractive index characteristics. The refractive index characteristics of the retardation layer typically show a relationship of nx > ny ≥ nz. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny < nz may occur. The Nz coefficient of the retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and still more preferably 0.9 to 1.2. By satisfying such a relationship, when the retardation layer and the polarizing plate with an adhesive layer are used in an image display device, a very excellent reflected hue can be achieved.

[0032] The thickness of the retardation layer can be set so as to function most appropriately as a λ / 4 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 15 μm to 60 μm, more preferably 20 μm to 55 μm, and most preferably 20 μm to 50 μm.

[0033] The absolute value of the photoelastic coefficient of the retardation layer is preferably 20×10 -12 (m 2 / N) or less, more preferably 1.0×10 -12 (m 2 / N) to 15×10 -12 (m 2 / N), and more preferably 2.0 × 10 -12 (m 2 / N)~12×10 -12 (m 2 When the absolute value of the photoelastic coefficient is within such a range, display unevenness can be suppressed when the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate are applied to an image display device.

[0034] In a humidified TMA test in which the environment is changed in the order of 25°C / 50%RH, 60°C / 50%RH, and 60°C / 85%RH, the dimensional change rate of the retardation layer in the slow axis direction is preferably 0.45% or less, more preferably 0.35% or less, even more preferably 0.28% or less, and particularly preferably 0.22% or less. If the dimensional change rate of the retardation layer in the humidified TMA test is below this upper limit, peeling of the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate from the adherend in a high-humidity environment can be suppressed, and the high-humidity durability of the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate can be improved. In addition, in a humidified TMA test in which the environment is changed in the order of 25°C / 50%RH, 60°C / 50%RH, and 60°C / 85%RH, the dimensional change rate of the retardation layer in the slow axis direction is, for example, 0% or more. Furthermore, when the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate further have another retardation layer (not shown), the dimensional change rate of the retardation layer in the slow axis direction in the above-mentioned humid TMA test is measured in a state where the other retardation layer is attached to the retardation layer, and the range of the dimensional change rate is the same as that described above.

[0035] D-2. Retardation layer materials The retardation layer typically contains a resin containing at least one bond group selected from the group consisting of a carbonate bond and an ester bond. In other words, the retardation layer contains a polycarbonate-based resin, a polyester-based resin, or a polyestercarbonate-based resin (hereinafter, these may be collectively referred to as a polycarbonate-based resin, etc.). The polycarbonate-based resin, etc., contains at least one structural unit selected from the group consisting of a structural unit represented by the above general formula (1) and / or a structural unit represented by the above general formula (2). These structural units are structural units derived from divalent oligofluorene, and may be hereinafter referred to as an oligofluorene structural unit. Such polycarbonate-based resins, etc., have positive refractive index anisotropy.

[0036] In one embodiment, the retardation layer may further contain an acrylic resin. The content of the acrylic resin is 0.5% by mass to 1.5% by mass. In this specification, percentages or parts by "mass" have the same meaning as percentages or parts by "weight."

[0037] D-2-1. Polycarbonate resins, etc. <Oligofluorene structural unit> The oligofluorene structural unit is represented by the above general formula (1) or (2). In general formulas (1) and (2), R 1 ~R 3 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group, provided that R 4 ~R 9may be the same or different, and R 4 ~R 9 At least two adjacent groups among these may be bonded to each other to form a ring.

[0038] The content of oligofluorene structural units in polycarbonate-based resins and the like is preferably 1% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, even more preferably 15% by mass to 30% by mass, and particularly preferably 18% by mass to 25% by mass, based on the total resin. If the content of oligofluorene structural units is too high, problems such as an excessively high photoelastic coefficient, insufficient reliability, and insufficient retardation expression may occur. Furthermore, since the proportion of oligofluorene structural units in the resin is high, the flexibility of molecular design is narrowed, and improvements to the resin may be difficult to achieve. On the other hand, even if the desired reverse dispersion wavelength dependence is obtained with a very small amount of oligofluorene structural units, the optical properties may change sensitively depending on slight variations in the content of the oligofluorene structural units, making it difficult to manufacture the resin so that the various properties fall within a certain range.

[0039] Details of the oligofluorene structural unit are described, for example, in International Publication No. 2015 / 159928, which is incorporated herein by reference.

[0040] <Other structural units> Polycarbonate resins and the like may typically contain other structural units in addition to oligofluorene structural units. In one embodiment, the other structural units may preferably be derived from dihydroxy compounds or diester compounds. In order to achieve the desired reverse dispersion wavelength property, it is necessary to incorporate structural units having positive intrinsic birefringence into the polymer structure together with oligofluorene structural units having negative intrinsic birefringence. Therefore, as other monomers to be copolymerized, dihydroxy compounds or diester compounds, which are raw materials for structural units having positive birefringence, are more preferred.

[0041] Examples of copolymerizable monomers include compounds that can introduce a structural unit containing an aromatic ring, and compounds that do not introduce a structural unit containing an aromatic ring, that is, compounds that are composed of an aliphatic structure. Specific examples of the compound having the aliphatic structure include dihydroxy compounds of straight-chain aliphatic hydrocarbons such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol and hexylene glycol; and 1,2-cyclohexanediol. dihydroxy compounds which are secondary and tertiary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecanedimethanol, 2,6-decane dimethanol, and the like; dihydroxy compounds which are primary alcohols of alicyclic hydrocarbons, exemplified by dihydroxy compounds derived from terpene compounds such as diphenyl dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantanedimethanol, and limonene; oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and polypropylene glycol; dihydroxy compounds having a cyclic ether structure such as isosorbide; dihydroxy compounds having a cyclic acetal structure such as spiroglycol and dioxane glycol; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Specific examples of compounds into which the structural unit containing an aromatic ring can be introduced include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)propane, )methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3- ...diphenylmethane, 1,1-bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4- Bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4, Aromatic bisphenol compounds such as 4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether; dihydroxy compounds having an ether group bonded to an aromatic group such as 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, and bis(4-(2-hydroxyethoxy)phenyl)sulfone;Aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; The aliphatic dicarboxylic acid and aromatic dicarboxylic acid components listed above can be used as raw materials for the polyester carbonate as dicarboxylic acids themselves, but depending on the production method, dicarboxylic acid esters such as methyl esters and phenyl esters, or dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

[0042] As copolymerization monomers, dihydroxy compounds having a fluorene ring, such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, which are conventionally known as compounds having structural units with negative birefringence, and dicarboxylic acid compounds having a fluorene ring can also be used in combination with oligofluorene compounds.

[0043] The resin used in the present invention preferably contains a structural unit represented by the following formula (3) as a copolymerization component, among the structural units that can be introduced by the compound having an alicyclic structure. [ka]

[0044] As a dihydroxy compound capable of introducing the structural unit of the formula (3), spiroglycol can be used.

[0045] In the resin used in the present invention, the structural unit represented by formula (3) is preferably contained in an amount of 5% by mass or more and 90% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more. When the content of the structural unit represented by formula (3) is equal to or greater than the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Furthermore, compatibility with acrylic resins is improved, and the transparency of the resulting resin composition can be further improved. Furthermore, since the polymerization reaction rate of spiroglycol is relatively slow, the polymerization reaction can be easily controlled by limiting the content to the upper limit or less.

[0046] The resin used in the present invention preferably further contains a structural unit represented by the following formula (4) as a copolymerization component. [ka]

[0047] Dihydroxy compounds capable of introducing the structural unit represented by the formula (4) include isosorbide (ISB), isomannide, and isoidet, which are stereoisomers. These may be used alone or in combination of two or more.

[0048] In the resin used in the present invention, the structural unit represented by formula (4) is preferably contained in an amount of 5% by mass or more and 90% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, and particularly preferably 15% by mass or more. When the content of the structural unit represented by formula (4) is equal to or greater than the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient are obtained. Furthermore, since the structural unit represented by formula (4) has high water absorption properties, when the content of the structural unit represented by formula (4) is equal to or less than the upper limit, dimensional change of the molded article due to water absorption can be kept within an acceptable range.

[0049] The resin used in the present invention may further contain other structural units. Such structural units may be referred to as "other structural units." As monomers having other structural units, it is more preferable to use 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, and 1,4-cyclohexanedicarboxylic acid (and derivatives thereof), with 1,4-cyclohexanedimethanol and tricyclodecane dimethanol being particularly preferable. Resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, and the like. Furthermore, since the polymerization reactivity of diester compounds is relatively low, it is preferable not to use diester compounds other than those containing oligofluorene structural units, from the viewpoint of increasing reaction efficiency.

[0050] The glass transition temperature (Tg) of the resin used in the present invention is preferably 110°C or higher and 160°C or lower. The upper limit is more preferably 155°C or lower, more preferably 150°C or lower, and particularly preferably 145°C or lower. The lower limit is more preferably 120°C or higher, and particularly preferably 130°C or higher. If the glass transition temperature is outside the above range, heat resistance tends to deteriorate, which may cause dimensional changes after film formation or may reduce the reliability of the quality of the retardation film under its usage conditions. On the other hand, if the glass transition temperature is excessively high, unevenness in film thickness may occur during film formation, the film may become brittle, the stretchability may deteriorate, and the transparency of the film may be impaired.

[0051] Details of the composition and manufacturing method of polycarbonate-based resins and the like are described, for example, in International Publication No. 2015 / 159928 (cited above), the disclosure of which is incorporated herein by reference.

[0052] D-2-2. Acrylic resin As the acrylic resin, an acrylic resin as a thermoplastic resin is used. Examples of monomers that form the structural units of the acrylic resin include the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate. Acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, cyclopentyl methacrylate, cyclopentyl acrylate, cyclohexyl methacrylate, cyclohexyl acrylate, cycloheptyl methacrylate, cycloheptyl acrylate, cyclooctyl methacrylate, cyclooctyl acrylate, cyclododecyl methacrylate, and cyclododecyl acrylate. These may be used alone or in combination of two or more. The form of using two or more kinds of monomers in combination includes copolymerization of two or more kinds of monomers, blend of two or more homopolymers of one kind of monomer, and combinations thereof. Furthermore, other monomers copolymerizable with these acrylic monomers (e.g., olefinic monomers, vinylic monomers) may be used in combination.

[0053] The acrylic resin contains structural units derived from methyl methacrylate. The content of the structural units derived from methyl methacrylate in the acrylic resin is preferably 70% by mass or more and 100% by mass or less. The lower limit is more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Within this range, excellent compatibility with the polycarbonate resin of the present invention can be obtained. As structural units other than methyl methacrylate, methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene are preferably used. Copolymerization of methyl acrylate can improve thermal stability. The refractive index of the acrylic resin can be adjusted by using phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene, and by matching it to the refractive index of the resin to be combined, the transparency of the resulting resin composition can be improved. The use of such acrylic resins can produce reverse dispersion retardation films that are excellent in stretchability and retardation expression and have low haze.

[0054] The weight-average molecular weight Mw of the acrylic resin is 10,000 or more and 200,000 or less. The lower limit is preferably 30,000 or more, particularly preferably 50,000 or more. The upper limit is preferably 180,000 or less, particularly preferably 150,000 or less. When the molecular weight is within this range, compatibility with the polycarbonate resin is obtained, thereby improving the transparency of the final retardation film (retardation layer) and achieving the effect of sufficiently improving the extensibility during stretching. The weight-average molecular weight is a molecular weight measured by GPC in terms of polystyrene. Furthermore, from the viewpoint of compatibility, it is preferable that the acrylic resin does not substantially contain a branched structure. The absence of a branched structure can be confirmed by, for example, the GPC curve of the acrylic resin being unimodal.

[0055] D-2-3. Blends of polycarbonate resins and acrylic resins The polycarbonate-based resin or the like and the acrylic-based resin are blended, and the resulting resin composition is used in a method for producing a retardation film (retardation layer) (the production method will be described later in Section C-3). The polycarbonate-based resin or the like and the acrylic-based resin are preferably blended in a molten state. A typical example of a method for blending in a molten state is melt-kneading using an extruder. The kneading temperature (molten resin temperature) is preferably 200°C to 280°C, more preferably 220°C to 270°C, and even more preferably 230°C to 260°C. If the kneading temperature is within this range, pellets of a resin composition in which both resins are uniformly blended can be obtained while suppressing thermal decomposition. If the molten resin temperature in the extruder exceeds 280°C, discoloration and / or thermal decomposition of the resin may occur. On the other hand, if the molten resin temperature in the extruder is below 200°C, the resin viscosity may become too high, placing an excessive load on the extruder or the resin may not be sufficiently melted. Any appropriate configuration may be adopted for the extruder configuration, screw configuration, etc. In order to obtain a resin with transparency that can withstand optical film applications, it is preferable to use a twin-screw extruder. Furthermore, since there is a concern that residual low-molecular-weight components in the resin and low-molecular-weight thermally decomposed components during extrusion kneading may contaminate cooling rolls and conveying rolls in the film-forming process and stretching process, it is preferable to use an extruder equipped with a vacuum vent in order to remove these.

[0056] The content of the acrylic resin in the resin composition (and consequently, the retardation layer) is, for example, 0.5% by mass or more and 2.0% by mass or less. The lower limit is more preferably 0.6% by mass or more. The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.9% by mass or less, and particularly preferably 0.8% by mass or less. In this way, by blending the acrylic resin with the polycarbonate resin in a very limited ratio, it is possible to significantly increase the extensibility and retardation expression. Furthermore, it is possible to suppress haze. This effect is not theoretically clear, but is an unexpected and excellent effect obtained through trial and error. Note that if the content of the acrylic resin is too low, the above effect may not be obtained. On the other hand, if the content of the acrylic resin is too high, the haze may become high. Furthermore, the extensibility and retardation expression may be insufficient or even deteriorate compared to when the content is within the above range.

[0057] The resin composition may be further blended with synthetic resins such as aromatic polycarbonate, aliphatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, AS, polylactic acid, polybutylene succinate, rubber, or combinations thereof, for the purpose of improving mechanical properties and / or solvent resistance.

[0058] The resin composition may further contain additives. Specific examples of additives include heat stabilizers, antioxidants, catalyst deactivators, UV absorbers, light stabilizers, release agents, dyes and pigments, impact modifiers, antistatic agents, slip agents, lubricants, plasticizers, compatibilizers, nucleating agents, flame retardants, inorganic fillers, and foaming agents. The type, number, combination, and content of the additives contained in the resin composition can be appropriately set depending on the purpose.

[0059] D-3. Method for forming retardation layer The retardation layer can be obtained by forming a film from the resin composition described in Section D-2 above and then stretching the film. Any appropriate molding method can be used to form a film from the resin composition. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, cast coating (e.g., casting), calendar molding, and heat pressing. Among these, extrusion molding and cast coating are preferred, as they can improve the smoothness of the resulting film and provide good optical uniformity. Since cast coating can cause problems due to residual solvent, extrusion molding is particularly preferred, and melt extrusion molding using a T-die is particularly preferred from the perspectives of film productivity and ease of subsequent stretching. The molding conditions can be appropriately set depending on the composition and type of resin used, the properties desired for the retardation layer, and the like. In this way, a resin film containing a polycarbonate-based resin or the like and an acrylic-based resin can be obtained.

[0060] The thickness of the resin film (unstretched film) can be set to any appropriate value depending on the desired thickness of the resulting retardation layer, the desired optical properties, the stretching conditions described below, etc. It is preferably 50 μm to 300 μm.

[0061] The stretching may be performed using any suitable stretching method and conditions (e.g., stretching temperature, stretch ratio, stretching direction). Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinkage, and fixed-end shrinkage may be used alone, simultaneously, or sequentially. Stretching may be performed in various directions or dimensions, such as the length direction, width direction, thickness direction, and oblique direction.

[0062] By appropriately selecting the stretching method and stretching conditions, a retardation layer having the desired optical properties (for example, refractive index properties, in-plane retardation, Nz coefficient) can be obtained.

[0063] In one embodiment, the stretching temperature of the film is a temperature below the glass transition temperature (Tg) of the polycarbonate-based resin or the like. Usually, when stretching a film of a polycarbonate-based resin or the like, the film is in a glassy state at temperatures below Tg, making stretching substantially impossible. According to the resin film used in the embodiment of the present invention, by blending a small amount of an acrylic resin (typically, polymethyl methacrylate), stretching at a temperature below Tg becomes possible without substantially changing the Tg of the polycarbonate-based resin or the like. Furthermore, although not theoretically clear, stretching at a temperature below Tg can realize a reverse dispersion retardation film (retardation layer) that is excellent in stretchability and retardation development and has low haze. Specifically, the stretching temperature is preferably Tg to Tg - 10°C, more preferably Tg to Tg - 8°C, and even more preferably Tg to Tg - 5°C. The film can be appropriately stretched even at temperatures higher than Tg, for example, up to about Tg + 5°C or, for example, up to about Tg + 2°C.

[0064] In this manner, a retardation film constituting a retardation layer can be obtained.

[0065] In addition, a commercially available stretched film can also be used as the retardation film. The commercially available stretched film may be used as is, or may be subjected to secondary processing (for example, stretching treatment, surface treatment) depending on the purpose. A specific example of a commercially available film is "Pure Ace RM" manufactured by Teijin Limited.

[0066] E. First Adhesive Layer and Second Adhesive Layer E-1. Characteristics of the first adhesive layer and / or the second adhesive layer As described above, the first pressure-sensitive adhesive layer 20 has an adhesive slippage of 900 μm or less, preferably 600 μm or less, more preferably 500 μm or less, even more preferably 400 μm or less, particularly preferably 300 μm or less, particularly preferably 250 μm or less, and most preferably 180 μm or less after a heating test at 85°C for 500 hours. The lower limit of the adhesive slippage may be, for example, 20 μm. By using a pressure-sensitive adhesive having an adhesive slippage within this range (preferably a small adhesive slippage) to bond the polarizer and the retardation layer, a retardation layer and a pressure-sensitive adhesive layer-attached polarizing plate with reduced retardation unevenness under high-temperature conditions can be realized due to the synergistic effect of controlling the creep value of the second pressure-sensitive adhesive layer described below. In this specification, the term "adhesive slippage" refers to the length of the largest portion of the adhesive layer protruding from the edge surfaces of the polarizer and the retardation layer in the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate after a heating test.

[0067] As described above, the creep value of the second adhesive layer 40 at 85°C is 40 μm or less, preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and particularly preferably 15 μm or less. The lower limit of the creep value can be, for example, 5 μm. By using an adhesive with such a low creep value to bond the retardation layer and the adhesive layer-attached polarizing plate to the image display cell, an image display device with reduced color unevenness in a high-temperature environment can be realized due to the synergistic effect of controlling the adhesive slippage of the first adhesive layer. The creep value can be measured, for example, by the following procedure: A test sample cut from an adhesive sheet is attached to a support plate at a 10 mm x 10 mm bonding surface. In an 85°C environment, a load of 500 gf is applied vertically downward while the support plate to which the test sample is attached is fixed. The amount of slippage from the support plate is measured 1 second and 3600 seconds after applying the load, and Cr1 and Cr2 are obtained, respectively. 3600 Let Cr1 and Cr 3600 The creep value is determined as ΔCr by the following formula: Note that the creep value in this specification is a value converted into a pressure-sensitive adhesive layer thickness of 20 μm. ΔCr=Cr 3600 -Cr1

[0068] The first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer preferably have a storage modulus at 85°C of 1.0 x 10 4 Pa or more, preferably 2.0 × 10 4 Pa or more, more preferably 5.0 × 10 4 Pa or more, and more preferably 1.0 × 10 5 If the storage modulus is within this range, it is easy to achieve the desired adhesive slippage and / or creep value. On the other hand, the storage modulus is, for example, 3.0×10 6 Pa or less.

[0069] The thickness of the first pressure-sensitive adhesive layer is preferably 2 μm to 50 μm, more preferably 3 μm to 40 μm. The thickness of the second pressure-sensitive adhesive layer is preferably 4 μm to 30 μm, more preferably 5 μm to 20 μm. When the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are within these ranges, a synergistic effect with the effect of controlling the adhesive slippage and creep value can be achieved, thereby realizing a retardation layer and a pressure-sensitive adhesive layer-attached polarizing plate in which retardation unevenness in high-temperature environments is suppressed, and an image display device in which color unevenness in high-temperature environments is suppressed can be realized.

[0070] E-2. Materials for the first adhesive layer and the second adhesive layer The first and second pressure-sensitive adhesive layers may have any suitable configuration, so long as the first pressure-sensitive adhesive layer has the desired adhesive slippage and the second pressure-sensitive adhesive layer has the desired creep value. The first and second pressure-sensitive adhesive layers may be composed of the same adhesive, or different adhesives. Hereinafter, the first and second pressure-sensitive adhesive layers will be collectively referred to as the pressure-sensitive adhesive layer, and the constituent materials will be described. The adhesive slippage and / or creep value can be controlled by adjusting the composition of the adhesive constituting the pressure-sensitive adhesive layer (e.g., the type of base polymer (polarity, Tg, softness), molecular weight), crosslinking structure (e.g., the type of crosslinking agent, the distance between crosslinking points (molecular weight between crosslinking points), crosslinking density), etc.

[0071] E-2-1. Base polymer The pressure-sensitive adhesive layer is typically formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a urethane polymer, a silicone polymer, or a rubber polymer as a base polymer. When a (meth)acrylic polymer is used as the base polymer, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing, for example, a (meth)acrylic polymer (A). The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main component.

[0072] <(Meth)acrylic polymer (A)> As described above, the (meth)acrylic polymer (A) contains alkyl (meth)acrylate as a main component. From the viewpoint of improving the adhesiveness of the pressure-sensitive adhesive layer, the alkyl (meth)acrylate preferably accounts for 50% by weight or more of all monomer components forming the (meth)acrylic polymer (A), and can be arbitrarily set as the remainder of the monomers other than the alkyl (meth)acrylate. Here, (meth)acrylate refers to acrylate and / or methacrylate.

[0073] The alkyl (meth)acrylate constituting the main skeleton of the (meth)acrylic polymer (A) may be a linear or branched alkyl group having 1 to 18 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. The alkyl (meth)acrylates may be used alone or in combination. The average number of carbon atoms in the alkyl group is preferably 3 to 10.

[0074] The (meth)acrylic polymer (A) may contain, as a monomer component, a copolymerizable monomer such as a carboxyl group-containing monomer (a1) or a hydroxyl group-containing monomer (a2) in addition to the alkyl (meth)acrylate. The copolymerizable monomers may be used alone or in combination.

[0075] The carboxyl group-containing monomer (a1) is a compound containing a carboxyl group and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group in its structure. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Among these, acrylic acid is preferred from the viewpoints of copolymerizability, cost, and improving the adhesive properties of the adhesive layer. The adhesive composition constituting the first adhesive layer and / or the adhesive composition constituting the second adhesive layer may preferably contain a carboxyl group-containing monomer, more preferably acrylic acid, as a monomer component of the (meth)acrylic polymer (A) (base polymer).

[0076] When a carboxyl group-containing monomer (a1) is used as a monomer component, the content of the carboxyl group-containing monomer (a1) is usually 0.01% by weight or more and 10% by weight or less of the total monomer components forming the (meth)acrylic polymer (A).

[0077] The hydroxyl group-containing monomer (a2) is a compound containing a hydroxyl group and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group in its structure. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and (4-hydroxymethylcyclohexyl)-methyl acrylate. Among these, from the viewpoint of improving the durability of the pressure-sensitive adhesive layer, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred.

[0078] When the hydroxyl group-containing monomer (a2) is used as a monomer component, the content of the hydroxyl group-containing monomer (a2) is usually 0.01% by weight or more and 10% by weight or less of the total monomer components forming the (meth)acrylic polymer (A).

[0079] The (meth)acrylic polymer (A) preferably contains, as a monomer component, a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 0°C or higher. Examples of the monomer (a3) ​​having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 0°C or higher include alkyl (meth)acrylate monomers and (meth)acrylic acid. The monomer (a3) ​​is preferably a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 20°C or higher, and more preferably a monomer having an unsaturated carbon-carbon double bond that results in a homopolymer having a glass transition temperature of 40°C or higher.

[0080] The content of the monomer (a3) ​​in the (meth)acrylic polymer (A) is not particularly limited. The content is usually 0.1 to 40% by weight, more preferably 1 to 30% by weight. When two or more types of monomer (a3) ​​are used in combination, the content is the total content.

[0081] Examples of the monomer (a3) ​​include methyl acrylate (Tg: 8°C), methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-propyl acrylate (Tg: 3°C), n-propyl methacrylate (Tg: 35°C), n-pentyl acrylate (Tg: 22°C), n-tetradecyl acrylate (Tg: 24°C), n-hexadecyl acrylate (Tg: 35°C), n-hexadecyl methacrylate (Tg: 15°C), n-stearyl acrylate (Tg: 30°C), and n-stearyl methacrylate (Tg: 38°C). Examples of suitable alkyl (meth)acrylates include linear alkyl (meth)acrylates, branched alkyl (meth)acrylates such as t-butyl acrylate (Tg: 43° C.), t-butyl methacrylate (Tg: 48° C.), i-propyl methacrylate (Tg: 81° C.), and i-butyl methacrylate (Tg: 48° C.), cyclic alkyl (meth)acrylates such as cyclohexyl acrylate (Tg: 19° C.), cyclohexyl methacrylate (Tg: 65° C.), isobornyl acrylate (Tg: 94° C.), and isobornyl methacrylate (Tg: 180° C.), and acrylic acid (Tg: 106° C.). These may be used alone or in combination.

[0082] When the pressure-sensitive adhesive composition contains a crosslinking agent described below, the copolymerizable monomer serves as a reaction site with the crosslinking agent. Carboxyl group-containing monomers and hydroxyl group-containing monomers are highly reactive with the intermolecular crosslinking agent, and are therefore preferably used to improve the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer. In addition, carboxyl group-containing monomers are preferred in terms of achieving both durability and reworkability, and hydroxyl group-containing monomers are preferred in terms of improving reworkability.

[0083] Other copolymerizable monomers (a4) may be further used as monomer components. The other copolymerizable monomers (a4) have a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group. By using the other copolymerizable monomers (a4), the adhesive properties and heat resistance of the pressure-sensitive adhesive layer can be improved. The other copolymerizable monomers (a4) can be used alone or in combination.

[0084] The adhesiveness of the pressure-sensitive adhesive layer can be improved by using an amino group-containing monomer or an amide group-containing monomer as the other copolymerizable monomer (a4). Examples of the amino group-containing monomer include N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of the amide group-containing monomer include acrylamide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, and mercaptoethyl(meth)acrylamide; N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

[0085] The other copolymerizable monomer (a4) may be a polyfunctional monomer. The use of a polyfunctional monomer allows for adjustment of the gel fraction and control of the cohesive strength of the pressure-sensitive adhesive layer. Examples of polyfunctional monomers include polyfunctional acrylates such as hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate; and divinylbenzene. The polyfunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate.

[0086] Examples of the other copolymerizable monomers (a4), in addition to those mentioned above, include (meth)acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate; cyclopolymerizable monomers such as methyl 2-(allyloxymethyl)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; and sulfonic acid group-containing monomers such as sodium vinyl sulfonate. Examples of suitable monomers include monomers; phosphate group-containing monomers; (meth)acrylic acid esters having an alicyclic hydrocarbon group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having an aromatic hydrocarbon group such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride. The pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer and / or the pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer may preferably contain a (meth)acrylic acid ester having an aromatic hydrocarbon group, more preferably benzyl (meth)acrylate, as the monomer component of the (meth)acrylic polymer (A) (base polymer).

[0087] The content of the other copolymerizable monomer (a4) in the (meth)acrylic polymer is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and particularly preferably 5% by mass or less.

[0088] The weight-average molecular weight Mw of the (meth)acrylic polymer (A) is, for example, 200,000 to 3,000,000, preferably 1,000,000 to 2,500,000, and more preferably 1,200,000 to 2,500,000. If the weight-average molecular weight Mw is within this range, a pressure-sensitive adhesive layer with excellent durability (particularly heat resistance) can be obtained. If the weight-average molecular weight Mw exceeds 3,000,000, an increase in viscosity and / or gelation during polymer polymerization may occur.

[0089] E-2-2. Silane coupling agents containing reactive functional groups The pressure-sensitive adhesive composition may contain a reactive functional group-containing silane coupling agent. The reactive functional group of the reactive functional group-containing silane coupling agent is typically a functional group other than an acid anhydride group. Examples of functional groups other than an acid anhydride group include epoxy groups, mercapto groups, amino groups, isocyanate groups, isocyanurate groups, vinyl groups, styryl groups, acetoacetyl groups, ureido groups, thiourea groups, (meth)acrylic groups, heterocyclic groups, and combinations thereof. The reactive functional group-containing silane coupling agents may be used alone or in combination.

[0090] When a reactive functional group-containing silane coupling agent is blended into the pressure-sensitive adhesive composition, the amount of the reactive functional group-containing silane coupling agent blended is usually 0.001 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the (meth)acrylic polymer (A).

[0091] E-2-3. Crosslinking agent The pressure-sensitive adhesive composition may contain a crosslinking agent. Examples of crosslinking agents that can be used include organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Polyfunctional metal chelates are compounds in which a polyvalent metal is covalently or coordinately bonded to an organic compound. When the pressure-sensitive adhesive composition is a radiation-curable type, a polyfunctional monomer can be used as the crosslinking agent. The crosslinking agents can be used alone or in combination.

[0092] When a crosslinking agent is incorporated into the pressure-sensitive adhesive composition, the amount of crosslinking agent is typically 0.01 to 15 parts by weight per 100 parts by weight of the (meth)acrylic polymer (A) (base polymer). The pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer preferably contains 1.5 parts by weight or more, more preferably 2.0 parts by weight or more, even more preferably 2.2 parts by weight or more, and particularly preferably 5 parts by weight or more of the crosslinking agent per 100 parts by weight of the (meth)acrylic polymer (A). When the amount of crosslinking agent in the pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer is equal to or greater than this lower limit, the synergistic effect of the crosslinking agent in the pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer with the effect of controlling the adhesive slippage and creep value can stably suppress retardation unevenness of the retardation layer and the pressure-sensitive adhesive layer-attached polarizing plate in a high-temperature environment, and can stably suppress color unevenness of the image display device in a high-temperature environment.

[0093] When an isocyanate crosslinking agent is blended into the pressure-sensitive adhesive composition, the amount of the isocyanate crosslinking agent blended is usually 0.01 to 15 parts by weight per 100 parts by weight of the (meth)acrylic polymer.

[0094] When a peroxide is blended into the pressure-sensitive adhesive composition, the blending amount of the peroxide is usually 0.01 to 2 parts by weight per 100 parts by weight of the (meth)acrylic polymer. Within this range, it is easy to adjust the processability, crosslinking stability, etc.

[0095] E-2-4. Additives The pressure-sensitive adhesive composition may contain a (meth)acrylic oligomer and / or an ionic compound. The pressure-sensitive adhesive composition may also contain additives. Specific examples of additives include colorants, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, and foil-like materials. A redox system incorporating a reducing agent may also be employed within a controllable range. In one embodiment, the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer may contain a polyether compound having a reactive group (e.g., a reactive silyl group). The type, number, combination, and content of the additives may be appropriately determined depending on the purpose. The content of the additive is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and even more preferably 1 part by weight or less, per 100 parts by weight of the (meth)acrylic polymer (A).

[0096] F. Image display device The retardation layer and pressure-sensitive adhesive layer-attached polarizing plate described in the above items A to E can be applied to an image display device. Therefore, embodiments of the present invention also include image display devices using such retardation layer and pressure-sensitive adhesive layer-attached polarizing plate. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes, on its viewing side, a retardation layer and a pressure-sensitive adhesive layer-attached polarizing plate described in the above items A to E. The image display device includes an image display panel. The image display panel includes an image display cell. Note that the image display device may be referred to as an optical display device, the image display panel may be referred to as an optical display panel, and the image display cell may be referred to as an optical display cell. [Example]

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows.

[0098] (1) Amount of adhesive misalignment The polarizing plates with retardation layers and adhesive layers obtained in the Examples and Comparative Examples were cut into 13-inch pieces to prepare test samples. The test samples were subjected to a heating test at 85°C for 500 hours, and the amount of the first adhesive layer that protruded from the edge surfaces of the polarizer and retardation layer after the heating test was observed and measured using an objective lens (20x magnification). The length of the largest protruding part of the first adhesive layer was taken as the adhesive slippage. During observation, the transmitted light was set to 0 (zero) and the observation was adjusted to be performed using reflected light. (2) Creep value The polarizing plates with retardation layers and adhesive layers obtained in Examples and Comparative Examples were cut into a size of 10 mm x 30 mm to prepare test samples. The upper end of the test sample (10 mm x 10 mm) was attached to a SUS plate via a second adhesive layer, and a load of 500 gf was applied vertically downward to the lower end of the test sample. In an environment of 85°C, the amount of displacement between the test sample and the SUS plate was measured 1 second and 3600 seconds after applying the load, and the values ​​of Cr1 and Cr 3600 Cr1 and Cr 3600 The creep value was determined as ΔCr by the following formula: ΔCr=Cr 3600 -Cr1 (3) Color unevenness The polarizing plates with retardation layers and adhesive layers obtained in Examples and Comparative Examples were cut into 13-inch pieces and attached to a glass plate via a second adhesive layer to prepare test samples. The test samples were subjected to a heating test at 85°C for 500 hours, and after the heating test, they were placed on a reflective sheet (DMS vapor deposition film, manufactured by Toray Advanced Film Co., Ltd.), and the reflection hue a of the center of the sample was measured using a spectrophotometer (product name "CM-2600d" manufactured by Konica Minolta, Inc.). * C and b * C , and the reflection hue a at the sample edge * E and b * E The Δab calculated by the following formula was used as an index of color unevenness. The smaller the Δab, the better the color unevenness. Δab={(a * E -a* C ) 2 +(b * E -b * C ) 2} 1 / 2 (4) Light leakage Two polarizing plates with a retardation layer and a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples were cut into a size of 300 mm length x 185 mm width to prepare them. These were laminated to both sides of a 0.07 mm thick alkali-free glass plate in a cross-Nicol configuration using a laminator to prepare a primary sample. The primary sample was then autoclaved at 50°C and 5 atm for 15 minutes (the sample after autoclaving is referred to as the "initial secondary sample"). The initial secondary sample was then subjected to treatment at 85°C for 500 hours (the sample after heating is referred to as the "heated secondary sample"). The initial secondary sample and the heated secondary sample were placed on a 10,000 candela backlight, and light leakage was visually observed and evaluated according to the following criteria. A: No light leakage occurs. B: There is a slight amount of light leakage, but it does not occur in the display area and does not pose a problem in practical use. C: A small amount of light leakage occurs in the display area, but this does not pose a problem in practical use. D: Light leakage is noticeable in the display area, and there is a problem in practical use. (5)Durability The polarizing plates with retardation layers and adhesive layers obtained in the Examples and Comparative Examples were cut into a size of 300 mm length x 220 mm width and attached to an alkali-free glass plate via a second adhesive layer to prepare test samples. The test samples were subjected to a durability test for 240 hours under conditions of 60°C and 95% relative humidity. After the durability test, the test samples were visually observed and evaluated according to the following criteria. A: There is no change in appearance such as foaming or peeling of the adhesive layer. B: A small amount of foaming occurs at the edge of the adhesive layer, but this does not pose a problem in practical use. C: Significant peeling occurred at the edge of the adhesive layer, and there is a problem in practical use. (6) Dimensional change rate due to humidification (humidification TMA test) A retardation film laminate was obtained by laminating a second retardation film to the first retardation film obtained in the manufacturing example so as to obtain the combination of the first retardation layer and the second retardation layer shown in Table 1. The obtained laminate was cut into a size of 20 mm (the slow axis direction of the first retardation film) x 5 mm (the fast axis direction of the first retardation film) to obtain a measurement sample. In Example 9, the second retardation film was not laminated to the first retardation film, and the first retardation film was cut to obtain a measurement sample. Using a thermomechanical analyzer, the environment was changed in the order of 25 ° C. / 50% RH, 60 ° C. / 50% RH, and 60 ° C. / 85% RH, and then the dimensional change rate in the length direction of the measurement sample (the slow axis direction of the first retardation film) was measured at 60 ° C. / 85% RH. The holding time at 25°C / 50% RH was 30 minutes, the holding time at 50°C / 60% RH was 60 minutes, and the holding time at 60°C / 85% RH was 240 minutes. The temperature rise rate between 25°C / 50% RH and 60°C / 50% RH was 0.4°C / min. The results are shown in Table 1.

[0099] [Compound abbreviation] The abbreviations for the compounds used in the following production examples are as follows. BPFM: Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane It was synthesized by the method described in JP 2015-25111 A. [ka] ISB: Isosorbide [Rocket Fleuret] SPG: Spiroglycol [Mitsubishi Gas Chemical Company, Inc.] DPC: Diphenyl carbonate [Mitsubishi Chemical Corporation]

[0100] [Production Example 1: Production of first retardation film constituting first retardation layer] Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100° C. The polymerization mixture contained 29.60 parts by mass (0.046 mol) of BPFM, 29.21 parts by mass (0.200 mol) of ISB, 42.28 parts by mass (0.139 mol) of SPG, 63.77 parts by mass (0.298 mol) of DPC, and 1.19 × 10 calcium acetate monohydrate as a catalyst. -2 Part of mass (6.78×10 -5 (mol) was charged. After purging the reactor with nitrogen under reduced pressure, heating was performed using a heat transfer medium. Stirring was initiated when the internal temperature reached 100°C. Forty minutes after the start of the temperature increase, the internal temperature reached 220°C. This temperature was maintained while simultaneously reducing the pressure. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 100°C, and the 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, heating and depressurization of the second reactor were initiated, and the internal temperature reached 240°C and the pressure reached 0.2 kPa in 50 minutes. The polymerization was then 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 resin produced was extruded into water, and the strands were cut to obtain pellets.

[0101] The resulting polyester carbonate resin pellets were vacuum-dried at 80°C for 5 hours, and then a 135 μm-thick, long resin film was produced using a film-forming device equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder temperature setting: 250°C), a T-die (width: 200 mm, temperature setting: 250°C), a chill roll (temperature setting: 120-130°C), and a winder. The resulting long resin film was stretched in the width direction at a stretching temperature of 133°C and a stretch ratio of 2.8 to obtain a 48 μm-thick retardation film R1. The Re(550) of the retardation film R1 was 141 nm, the Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12.

[0102] [Production Example 2: Production of first retardation film constituting first retardation layer] 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 purging the reactor with nitrogen under reduced pressure, it was heated with a heat medium. Stirring was initiated when the internal temperature reached 100°C. Forty minutes after the start of the temperature increase, the internal temperature reached 220°C. This temperature was maintained while simultaneously reducing the pressure. 90 minutes after reaching 220°C, the pressure was reduced to 13.3 kPa. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 110°C, and the 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 increase and pressure reduction in the second reactor were initiated, reaching an internal temperature of 240°C and a pressure of 20 kPa in 40 minutes. The pressure was then further reduced, and polymerization was allowed to proceed until the specified stirring power was achieved. When the specified power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate was extruded into water, and strands were cut to obtain pellets. This resin is designated "PC1." The ratio of structural units derived from each monomer was BPFM / ISB / SPG / DPC = 21.5 / 39.4 / 30.0 / 9.1% by mass. PC1 had a reduced viscosity of 0.46 dL / g, Mw of 48,000, and a refractive index n D is 1.526, melt viscosity is 2480 Pa s, glass transition temperature is 139°C, and photoelastic coefficient is 9 × 10 -12 [m 2 / N], and the wavelength dispersion Re(450) / Re(550) was 0.85.

[0103] 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-making device equipped with a single-screw extruder (manufactured by Isuzu Chemical Engineering Co., Ltd., screw diameter 25 mm, cylinder temperature setting: 250°C), a T-die (width 300 mm, temperature setting: 220°C), a chill roll (temperature setting: 120-130°C), and a winder was used to produce a long unstretched film measuring 3 m in length, 200 mm in width, and 100 μm in thickness. This long unstretched film was stretched at a stretching temperature of Tg and a stretch ratio of 2.4 times.

[0104] In this way, a retardation film R2 constituting a retardation layer was obtained. The retardation film R2 exhibited refractive index characteristics of nx>ny>nz, Re(550) was 145 nm, and Re(450) / Re(550) was 0.85.

[0105] [Production Example 3: Production of first retardation film constituting first retardation layer] A commercially available polycarbonate resin film (stretched resin film, manufactured by Teijin Limited, product name "Pure Ace RM", thickness 50 μm) was used as retardation film R3. Re(550) of retardation film R3 was 147 nm, and Re(450) / Re(550) was 0.90.

[0106] [Production Example 4: Preparation of second retardation film constituting second retardation layer] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer (weight average molecular weight 5000) represented by the following chemical formula (I) (where 65 and 35 are the mol% of each structural unit), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name "Paliocolor LC242"), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name "Irgacure 907") in 200 parts by weight of cyclopentanone. Next, the prepared liquid crystal coating solution was applied to the surface of a norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name "Zeonex"), which is a substrate film, using a bar coater, and then heated and dried at 80 ° C for 4 minutes to align the liquid crystal contained in the coating film. Next, the coating film was cured by irradiation with ultraviolet light, and a liquid crystal solidified layer R4 (thickness 0.58 μm), which is a second retardation film, was formed on the substrate film. The in-plane retardation Re of the liquid crystal solidified layer R4 for light with a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction was −71 nm (nx=1.5326, ny=1.5326, nz=1.6550), and the liquid crystal solidified layer R4 exhibited refractive index characteristics of nz>nx=ny. [ka]

[0107] [Production Example 5: Preparation of adhesive] (Preparation of Acrylic Polymer A1) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 82.1 parts of butyl acrylate, 13 parts of benzyl acrylate, 0.1 parts of 4-hydroxybutyl acrylate, and 4.8 parts of acrylic acid. 100 parts of this monomer mixture was then charged with 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator along with 100 parts of ethyl acetate. Nitrogen gas was introduced with gentle stirring to replace the atmosphere. The temperature in the flask was maintained at around 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of acrylic polymer A1 with a weight average molecular weight (Mw) of 2.2 million and Mw / Mn = 3.0.

[0108] (Preparation of adhesive) 0.45 parts of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), 0.1 parts of peroxide crosslinking agent (benzoyl peroxide), 0.2 parts of epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403"), and 0.5 parts of polyether compound having a reactive silyl group (manufactured by Kaneka Corporation, trade name "Silyl SAT10") were blended with 100 parts of the solid content of the acrylic polymer A1 solution to obtain adhesive PSA1.

[0109] [Production Example 6: Preparation of adhesive] (Preparation of Acrylic Polymer A2) A solution of acrylic polymer A2 having Mw of 1.8 million and Mw / Mn=4.8 was prepared in the same manner as in Production Example 5, except that a monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was used.

[0110] (Preparation of adhesive) 0.1 parts of trimethylolpropane / xylylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Takenate D110N"), 0.3 parts of a peroxide crosslinking agent (benzoyl peroxide), and 0.2 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") were blended with 100 parts of the solid content of the acrylic polymer A2 solution to obtain adhesive PSA2.

[0111] [Production Example 7: Preparation of adhesive] A pressure sensitive adhesive PSA3 was obtained in the same manner as in Production Example 6, except that the amount of D110N was changed to 0.02 parts.

[0112] [Production Example 8: Preparation of adhesive] (Preparation of Acrylic Polymer A3) A solution of acrylic polymer A3 having a Mw of 2,200,000 and a Mw / Mn of 3.0 was prepared in the same manner as in Production Example 5, except that a monomer mixture containing 76.1 parts of butyl acrylate, 19 parts of benzyl acrylate, 0.1 parts of 4-hydroxybutyl acrylate, and 4.8 parts of acrylic acid was used.

[0113] (Preparation of adhesive) 2.5 parts of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L"), 0.1 parts of a peroxide crosslinking agent (benzoyl peroxide), and 0.2 parts of an epoxy group-containing oligomeric silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-41-1056") were blended with 100 parts of the solid content of the acrylic polymer A3 solution to obtain adhesive PSA4.

[0114] [Production Example 9: Preparation of adhesive] (Preparation of Acrylic Polymer A4) A solution of acrylic polymer A4 having a Mw of 2,200,000 and a Mw / Mn of 3.2 was prepared in the same manner as in Production Example 5, except that a monomer mixture containing 63.1 parts of butyl acrylate, 32 parts of benzyl acrylate, 0.1 parts of 4-hydroxybutyl acrylate, and 4.8 parts of acrylic acid was used.

[0115] (Preparation of adhesive) 2.5 parts of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L"), 0.1 parts of a peroxide crosslinking agent (benzoyl peroxide), and 0.2 parts of an epoxy group-containing oligomeric silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "X-41-1056") were blended with 100 parts of the solid content of the acrylic polymer A4 solution to obtain adhesive PSA5.

[0116] [Production Example 10: Preparation of adhesive] (Preparation of Acrylic Polymer A5) A solution of acrylic polymer A5 having a Mw of 2.2 million and a Mw / Mn of 3.9 was prepared in the same manner as in Production Example 5, except that a monomer mixture containing 94.9 parts of butyl acrylate, 0.1 parts of 2-hydroxyethyl acrylate, and 5 parts of acrylic acid was used.

[0117] (Preparation of adhesive) 100 parts of the solid content of the acrylic polymer A5 solution was mixed with 3.0 parts of a trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L"), 0.2 parts of a peroxide crosslinking agent (benzoyl peroxide), and 0.075 parts of an epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") to obtain adhesive PSA6.

[0118] [Production Example 11: Preparation of adhesive] The adhesive PSA7 was obtained in the same manner as in Production Example 6, except that 30 parts of a copolymer oligomer (Mw=4700) consisting of 94 parts of butyl acrylate, 4 parts of methyl acrylate, and 2 parts of acrylic acid were added to 100 parts of the solid content of the acrylic polymer A2 solution, the amount of D110N was changed to 0.02 parts, and the amount of silane coupling agent was changed to 0.1 parts.

[0119] [Production Example 12: Preparation of adhesive] 12.0 parts of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation, product name "Coronate L") and 0.1 parts of epoxy group-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") were blended with 100 parts of the solid content of the acrylic polymer A1 solution to obtain adhesive PSA8.

[0120] [Production Example 13: Preparation of adhesive] Pressure sensitive adhesive PSA9 was obtained in the same manner as in Production Example 12, except that the amount of Coronate L was changed to 2.5 parts.

[0121] [Production Example 14: Preparation of polarizing plate] (Fabrication of polarizer) A long roll of a 30 μm-thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") was uniaxially stretched in the longitudinal direction by 5.9 times using a roll stretching machine, while simultaneously undergoing swelling, dyeing, crosslinking, and washing processes, and finally drying, to produce a 12 μm-thick polarizer. Specifically, the film was stretched 2.2 times while being swelled in pure water at 20°C. Then, the film was stretched 1.4 times while being dyed in a 30°C aqueous solution containing iodine and potassium iodide at a weight ratio of 1:7, with the iodine concentration adjusted so that the resulting polarizer had a single transmittance of 45.0%. Furthermore, a two-stage crosslinking process was employed. In the first stage, the film was stretched 1.2 times while being treated in a 40°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the first stage was 5.0 wt % and the potassium iodide content was 3.0 wt %. In the second stage, the film was stretched 1.6 times while being treated in a 65°C aqueous solution containing boric acid and potassium iodide. The boric acid content of the aqueous solution used in the second stage was 4.3 wt % and the potassium iodide content was 5.0 wt %. The cleaning treatment was carried out with an aqueous potassium iodide solution at 20° C. The potassium iodide content of the aqueous solution used for the cleaning treatment was 2.6 wt %. Finally, the film was dried at 70° C. for 5 minutes to obtain a polarizer.

[0122] (Preparation of polarizing plate) A triacetyl cellulose film (thickness: 40 μm, manufactured by Konica Minolta, product name "KC4UYW") was attached to one side of the polarizer via a polyvinyl alcohol adhesive to obtain a polarizing plate P1 having a protective layer / polarizer configuration.

[0123] [Production Example 15: Preparation of polarizing plate] (Fabrication of polarizer) A long, amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 μm) having a Tg of about 75° C. was used as the thermoplastic resin substrate, and one side of the resin substrate was subjected to a corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin made by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFFIMER") in a 9:1 ratio, to which 13 parts by weight of potassium iodide was added, in water. The above PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm, thereby producing a laminate. The resulting laminate was uniaxially stretched 2.4 times in the machine direction (longitudinal direction) in an oven at 130°C (auxiliary in-air stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer would be a desired value (dyeing treatment). Next, the sample was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). The laminate was then immersed in a boric acid aqueous solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 70°C and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20° C. (cleaning treatment). Thereafter, the film was dried in an oven maintained at about 90°C, and brought into contact with a heated roll made of SUS whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this manner, a polarizer having a thickness of about 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizer structure was obtained.

[0124] (Preparation of polarizing plate) A cycloolefin film (ZF-12, 23 μm, manufactured by Zeon Corporation) was attached as a protective layer to the surface of the obtained polarizer (the surface opposite to the resin substrate) via a UV-curable adhesive. Specifically, the curable adhesive was applied so that the total thickness was approximately 1.0 μm, and the films were attached using a roller. The adhesive was then cured by irradiating it with UV light from the cycloolefin film side. The resin substrate was then peeled off to obtain polarizing plate P2 having a cycloolefin film (protective layer) / polarizer configuration.

[0125] (Preparation of adhesive layer) The prepared adhesive was applied to one side of a polyethylene terephthalate film (separator film, manufactured by Mitsubishi Chemical Polyester Film Corporation, MRF38) treated with a silicone-based release agent so that the adhesive layer would have a thickness of 12 μm after drying, and the adhesive coating was then dried to form a first adhesive layer. Furthermore, a second pressure-sensitive adhesive layer was formed in the same manner as the formation of the first pressure-sensitive adhesive layer, except that the coating was carried out so that the thickness of the pressure-sensitive adhesive layer after drying would be 15 μm.

[0126] [Examples 1 to 9 and Comparative Examples 1 and 2] The first pressure-sensitive adhesive layer formed on the surface of the separator film was transferred to a polarizing plate to produce a pressure-sensitive adhesive layer-attached polarizing plate, and the second pressure-sensitive adhesive layer formed on the surface of the separator film was transferred to a retardation film to produce a pressure-sensitive adhesive layer-attached retardation film. The pressure-sensitive adhesive layer-attached polarizing plate and the pressure-sensitive adhesive layer-attached retardation film were then combined in the order shown in Table 1, with the polarizing plate, first retardation film (retardation layer), second retardation film (liquid crystal solidified layer), and adhesive (first adhesive layer and second adhesive layer) being arranged in the order shown in Table 1, to produce a retardation layer and a pressure-sensitive adhesive layer-attached polarizing plate. The polarizing plate and the first retardation layer (retardation film) were attached together so that the absorption axis of the polarizer and the slow axis of the retardation film formed a 45° angle. The resulting retardation layer and pressure-sensitive adhesive layer-attached polarizing plate were then evaluated for color unevenness, light leakage, and durability. The results are shown in Table 1, along with the adhesive slippage of the first adhesive layer and the creep value of the second adhesive layer.

[0127] [Table 1]

[0128] [evaluation] As is clear from Table 1, by controlling the adhesive slippage of the first adhesive layer and the creep value of the second adhesive layer in combination, it is possible to obtain a retardation layer and a polarizing plate with an adhesive layer that can realize an image display device in which color unevenness and light leakage are suppressed in high-temperature environments. [Industrial Applicability]

[0129] The retardation layer and pressure-sensitive adhesive layer-attached polarizing plate of the present invention can be suitably used in image displays (typically, liquid crystal displays and organic EL displays). [Explanation of symbols]

[0130] 10 Polarizing plate 11 Polarizer 12 First protective layer 13 Second layer of protection 20 First adhesive layer 30 Retardation layer 40 Second adhesive layer 100 Polarizing plate with retardation layer and adhesive layer

Claims

[Claim 1] a polarizing plate including a polarizer; a retardation layer bonded to the polarizing plate via a first pressure-sensitive adhesive layer; and a second pressure-sensitive adhesive layer provided as an outermost layer on the retardation layer on the opposite side of the polarizing plate, the retardation layer is formed of a stretched resin film, and satisfies the relationship Re(450)<Re(550); the adhesive slippage of the first pressure-sensitive adhesive layer after a heating test at 85°C for 500 hours is 900 µm or less; the creep value of the second pressure-sensitive adhesive layer at 85°C is 40 µm or less; Polarizing plate with retardation layer and adhesive layer: Here, Re(450) and Re(550) are in-plane retardations measured at 23° C. using light with wavelengths of 450 nm and 550 nm, respectively.

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