Polarizing plate with phase difference layer and image display device

Abstract

To provide a polarizing plate with a phase difference layer that has excellent durability even in harsh high-temperature and high-humidity environments. [Solution] A polarizing plate with a phase difference layer according to an embodiment of the present invention comprises a first phase difference layer having a first main surface and a second main surface facing each other, a polarizer disposed on the first main surface side of the first phase difference layer, a first layer disposed on the second main surface side of the first phase difference layer, and / or a second layer disposed on the first main surface side of the first phase difference layer, wherein the first layer and the second layer are disposed in direct contact with the first phase difference layer, and the first phase difference layer is composed of a stretched film of a resin film, Re(450)

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a phase difference layer and an image display device. [Background technology]

[0002] In recent years, image display devices, such as liquid crystal displays and electroluminescent (EL) displays (e.g., organic EL displays and inorganic EL displays), have become rapidly widespread. Typically, polarizers and phase difference plates are used in image display devices. In practical terms, polarizers with an integrated phase difference layer are widely used (e.g., Patent Document 1). Recently, with the expanding applications of image display devices, there has been a demand for various performance improvements in polarizers with phase difference layers. For example, polarizers with phase difference layers may now require durability under harsh high-temperature and high-humidity environments, a requirement not previously necessary. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 3325560 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a polarizing plate with a phase difference layer that has excellent durability even under harsh high temperature and high humidity environments. [Means for solving the problem]

[0005] The retardation film - attached polarizing plate according to an embodiment of the present invention includes a first retardation film having first and second major surfaces facing each other, a polarizer disposed on the first major surface side of the first retardation film, and a first layer disposed on the second major surface side of the first retardation film. The first retardation film is composed of a stretched film of a resin film and satisfies the relationship Re(450) < Re(550). The first layer is a resin layer and has a shear fracture strength of 85 MPa or more. The retardation film - attached polarizing plate according to another embodiment of the present invention includes a first retardation film having first and second major surfaces facing each other, a polarizer disposed on the first major surface side of the first retardation film, a first layer disposed on the second major surface side of the first retardation film, and a second layer disposed on the first major surface side of the first retardation film. The first retardation film is composed of a stretched film of a resin film and satisfies the relationship Re(450) < Re(550). The first layer is a resin layer and has a shear fracture strength of 60 MPa or more. The second layer is a resin layer and has a shear fracture strength of 60 MPa or more. Here, Re(450) and Re(550) are the in - plane retardations measured with light of wavelengths 450 nm and 550 nm at 23°C, respectively. In one embodiment, Re(550) of the first retardation film is 100 nm to 200 nm, and the angle formed by the slow axis of the first retardation film and the absorption axis of the polarizer is 40° to 50° or 130° to 140°. In one embodiment, the retardation film - attached polarizing plate has a second retardation film disposed on the second major surface side of the first retardation film, and the second retardation film exhibits a refractive index characteristic of nz > nx = ny. The first layer is disposed between the first retardation film and the second retardation film. In one embodiment, the first layer functions as an adhesive layer. In one embodiment, the first retardation film contains at least one bonding group selected from the group consisting of carbonate bonds and ester bonds, 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 contains a resin having positive refractive index anisotropy: [ka] [ka] In general formulas (1) and (2), R 1 ~R 3 Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C4-C10 aryl group, a substituted or unsubstituted C1-C10 acyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C1-C10 aryloxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C10 vinyl group, a substituted or unsubstituted C1-C10 ethynyl group, a substituted sulfur atom, a substituted silicon atom, a halogen atom, a nitro group, or a cyano group; however, R 4 ~R 9 They may be the same or different from each other, R 4 ~R 9 At least two adjacent groups may be bonded to each other to form a ring. In one embodiment, the polarizing plate with a phase difference layer has a protective layer positioned on the opposite side of the polarizer from the first phase difference layer, and the shrinkage rate of the protective layer after being placed in an 85°C environment for 240 hours is less than 0.05%. In one embodiment, the protective layer is composed of a triacetylcellulose film or a cyclic olefin resin film. According to another aspect of the present invention, an image display device is provided. This image display device comprises the above-described polarizing plate with a phase difference layer. [Effects of the Invention]

[0006] According to embodiments of the present invention, a polarizing plate with a phase difference layer that has excellent durability even under harsh high-temperature and high-humidity environments can be realized. [Brief explanation of the drawing]

[0007] [Figure 1] It is a schematic cross-sectional view showing the schematic configuration of a polarizing plate with a retardation layer according to the first embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view showing the schematic configuration of a polarizing plate with a retardation layer according to the second embodiment of the present invention.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Further, for the sake of clarity of explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part compared with the embodiments, but this is merely an example and does not limit the interpretation of the present invention.

[0009] (Definition of Terms and Symbols) The definitions of the terms and symbols 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 maximum (i.e., the slow axis direction), 「ny」 is the refractive index in the direction orthogonal 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 Retardation (Re) 「Re(λ)」 is the in-plane retardation of the film measured with light of wavelength λ nm at 23°C. For example, 「Re(450)」 is the in-plane retardation of the film measured with light of wavelength 450 nm at 23°C. Re(λ) is obtained by the formula: Re = (nx - ny) × d when the thickness of the film is d (nm). (3) Retardation in the Thickness Direction (Rth) "Rth(λ)" is the phase difference in the thickness direction of the film measured with light of wavelength λnm at 23°C. For example, "Rth(450)" is the phase difference in the thickness direction of the film measured with light of wavelength 450nm at 23°C. Rth(λ) can be calculated using the formula: Rth = (nx - nz) × d, where d (nm) is the thickness of the film. (4) Nz coefficient The Nz coefficient is calculated using the formula Nz = Rth / Re. (5)Angle In this specification, when an angle is mentioned, unless otherwise specified, it includes angles in both clockwise and counterclockwise directions.

[0010] A. Polarizing plate with retardation layer Figure 1 is a schematic cross-sectional view showing the general configuration of a polarizing plate with a phase difference layer according to a first embodiment of the present invention. The polarizing plate with a phase difference layer 100 has a first phase difference layer 21 having a first main surface 21a and a second main surface 21b facing each other, a polarizing plate 10 disposed on the first main surface 21a side of the first phase difference layer 21, and a first layer 31, a second phase difference layer 22, and an adhesive layer 40 disposed on the second main surface 21b side of the first phase difference layer 21. The polarizing plate 10 includes a polarizer 11 and a protective layer 12 in that order from the first phase difference layer 21 side. No protective layer is disposed between the polarizer 11 and the first phase difference layer 21, and the first phase difference layer 21 is disposed adjacent to the polarizer 11 and can function as a protective material for the polarizer 11. Typically, the polarizing plate with a phase difference layer 100 is arranged in an image display device such that the polarizer 11 is on the viewing side of the first phase difference layer 21. A polarizing plate with a phase difference layer 100 can be obtained, for example, by laminating a polarizing plate 10, which is obtained by laminating a polarizer 11 and a protective layer 12, with other layers.

[0011] Figure 2 is a schematic cross-sectional view showing the general configuration of a polarizing plate with a phase difference layer according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that a second layer 32 is provided on the first main surface 21a side of the first phase difference layer 21. Specifically, the polarizing plate with a phase difference layer 100 further has a second layer 32 disposed between the polarizing plate 10 (polarizer 11) and the first phase difference layer 21.

[0012] In the illustrated example, the polarizing plate 10 includes a polarizer 11 and a protective layer 12 disposed on one side of the polarizer 11, but may further include a second protective layer disposed on the other side of the polarizer 11. Also, the polarizing plate 10 includes the polarizer 11 and the protective layer 12, but the protective layer 12 may be omitted.

[0013] The first retardation layer 21 is composed of a stretched film of a resin film and satisfies the relationship Re(450) < Re(550). Re(550) of the first retardation layer 21 is typically 100 nm to 200 nm. The angle formed by the slow axis of the first retardation layer 21 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°; or preferably 130° to 140°, more preferably 132° to 138°, still more preferably 134° to 136°, and particularly preferably about 135°.

[0014] Each member constituting the polarizing plate with a retardation layer can be laminated via an arbitrary appropriate adhesive layer (not shown). Specific examples of the adhesive layer include an adhesive layer and an adhesive agent layer. For example, the protective layer 12 is bonded to the polarizer 11 via an adhesive layer (preferably using an active energy ray-curable adhesive). The thickness of the adhesive layer is preferably 0.4 μm or more, more preferably 0.4 μm to 3.0 μm, and still more preferably 0.6 μm to 2.2 μm. For example, the first retardation layer 20 is bonded to the polarizing plate 10 (polarizer 11) via an adhesive agent layer (e.g., an acrylic adhesive). The thickness of the adhesive agent layer is preferably 1 μm to 10 μm.

[0015] An adhesive layer 40, positioned on the second main surface 21b side of the first phase difference layer 21, allows the polarizing plate 100 with the phase difference layer to be attached to an image display panel included in an image display device. The thickness of the adhesive layer 40 is preferably 10 μm to 20 μm. The adhesive layer 40 is composed of, for example, an acrylic adhesive. Although not shown, a release liner is practically bonded to the surface of the adhesive layer 40. The release liner can be temporarily attached until the polarizing plate with the phase difference layer is put into use. By using a release liner, for example, the adhesive layer 40 is protected and roll formation of the polarizing plate with the phase difference layer is possible.

[0016] The first layer 31 and the second layer 32 are resin layers. Specifically, the first layer 31 and the second layer 32 may each be a cured resin layer, a solidified resin layer, or a combination thereof. Preferably, the first layer 31 and the second layer 32 are arranged in direct contact with the first phase difference layer 21 (formed directly on the first phase difference layer 21). In one embodiment, the first layer 31 can function as an adhesive layer that fixes the first phase difference layer 21 to a layer arranged adjacent to the first phase difference layer 21 (for example, the second phase difference layer 22). Note that "adjacent" includes not only directly adjacent layers but also adjacent layers separated by an adhesive layer.

[0017] The shear fracture strength of the second layer 32 is preferably 60 MPa to 200 MPa, and more preferably 80 MPa to 120 MPa.

[0018] As shown in Figure 1, in a configuration in which the polarizing plate 100 with a phase difference layer does not have a second layer 32 (a configuration in which the polarizing plate 10 and the first phase difference layer 21 are arranged adjacent to each other), the shear fracture strength of the first layer 31 is greater than 80 MPa, preferably 85 MPa or more, and more preferably 90 MPa or more. On the other hand, it is preferable that the shear fracture strength of the first layer 31 is 200 MPa or less.

[0019] As shown in Figure 2, in a configuration in which the polarizing plate 100 with a phase difference layer has a second layer 32, the shear fracture strength of the first layer 31 is 40 MPa or more, preferably 50 MPa or more, and more preferably 60 MPa or more. On the other hand, the shear fracture strength of the first layer 31 is preferably 200 MPa or less, may be less than 85 MPa, or 80 MPa or less.

[0020] By providing a first layer, or a first and second layer, a polarizing plate with a phase difference layer that has excellent durability even in harsh high-temperature and high-humidity environments can be realized. Specifically, a polarizing plate with a phase difference layer that suppresses cracking and peeling even in harsh high-temperature and high-humidity environments can be realized. Details are as follows. The first phase difference layer used in the embodiment of the present invention exhibits excellent circular polarization characteristics, so a polarizing plate with a phase difference layer (circular polarizing plate) with excellent anti-reflective function can be realized. Furthermore, by using such a first phase difference layer in combination with a second phase difference layer whose refractive index characteristics, described later, show the relationship nz>nx=ny, it is possible to widen the viewing angle of the anti-reflective function. On the other hand, the stretched film of the resin film constituting the first phase difference layer has large thermal shrinkage and high water absorption, so its reliability in high-temperature and high-humidity environments may be insufficient, and furthermore, cracking and / or peeling may occur in harsh high-temperature and high-humidity environments, which are becoming a new standard for characteristics in recent years. According to embodiments of the present invention, by providing a first layer, or a first layer and a second layer, the durability and reliability of the polarizing plate with a phase difference layer as a whole can be significantly improved in harsh high-temperature and high-humidity environments while maintaining the excellent properties of the first phase difference layer. As a result, a polarizing plate with a phase difference layer that suppresses cracking and peeling even in harsh high-temperature and high-humidity environments can be realized. It should be noted that the above mechanism is a hypothesis and does not limit or restrict embodiments of the present invention.

[0021] The refractive index characteristics of the second phase difference layer 22, which may be included in a polarizing plate with a phase difference layer, typically exhibit the relationship nz > nx = ny. By providing such a phase difference layer, reflections in oblique directions can be effectively prevented, enabling a wider viewing angle for the anti-reflective function.

[0022] A polarizing plate with a phase difference layer may have a further phase difference layer (not shown). The optical properties (e.g., refractive index properties, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, placement, etc., of the further phase difference layer can be appropriately set according to the purpose.

[0023] The polarizing plate with a phase difference layer may be in the form of a single sheet or a long sheet. In this specification, "long sheet" means an elongated shape in which the length is sufficiently long relative to the width, and for example, includes an elongated shape in which the length is 10 times or more, preferably 20 times or more, relative to the width. The long polarizing plate with a phase difference layer can be wound into a roll.

[0024] B. Polarizer Any suitable polarizer can be used 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.

[0025] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to dyeing and stretching treatments with dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA film with iodine and uniaxially stretching are used because they have excellent optical properties.

[0026] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA film in water and washing it before dyeing can not only clean dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film to prevent uneven dyeing.

[0027] Specific examples of polarizers obtained using the above-mentioned laminate of two or more layers include polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or polarizers obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, preferably, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is formed on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may further include, if necessary, air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, the laminate is preferably subjected to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by heating while being transported in the longitudinal direction. Typically, the manufacturing method of this embodiment includes applying an air-assisted stretching treatment, a dyeing treatment, a water-based stretching treatment, and a drying shrinkage treatment to the laminate in this order. By introducing auxiliary stretching, it is possible to increase the crystallinity of PVA even when PVA is coated on a thermoplastic resin, making it possible to achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as a decrease in the orientation of PVA and dissolution when immersed in water in the subsequent dyeing and stretching processes, making it possible to achieve high optical properties. Furthermore, when the PVA-based resin layer is immersed in liquid, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to when the PVA-based resin layer does not contain halides. As a result, the optical properties of the polarizer obtained through processing steps in which the laminate is immersed in liquid, such as dyeing and water-based stretching, can be improved. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, the optical properties can be improved.The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or an appropriate protective layer may be laminated on the peeled surface obtained by removing the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface, depending on the purpose. Details of such polarizer manufacturing methods are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0028] The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, particularly preferably 8 μm or less, and especially preferably 5 μm or less. The lower limit of the polarizer thickness may be, for example, 1 μm. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good durability of the appearance during heating can be obtained.

[0029] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The 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 higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0030] C. Protective layer The protective layer 12 and the second protective layer (not shown) are each formed from any suitable film that can be used as a protective layer for the polarizer. Specific examples of materials that make up the main component of the film include cellulosic resins such as triacetylcellulose (TAC), and transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, cyclic olefin (e.g., polynorbornene), polyolefin, (meth)acrylic, and acetate. Thermosetting resins or UV-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone are also acceptable. In addition, glassy polymers such as siloxane polymers can also be used. Furthermore, the polymer film described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As materials for this film, for example, 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 groups and nitrile groups in its side chains can be used. Examples include a resin composition having an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the above resin composition.

[0031] The protective layer 12 preferably has a shrinkage rate of less than 0.05%, more preferably 0.04% or less, and even more preferably 0.03% or less after being placed in an 85°C environment for 240 hours. A smaller shrinkage rate is preferable, and its lower limit may be, for example, 0.01%. If the shrinkage rate is within this range, cracking of the polarizer and delamination between the polarizer and the phase difference layer can be suppressed more effectively under harsh high-temperature and high-humidity environments. The protective layer 12 is preferably composed of a triacetylcellulose (TAC) film or a cyclic olefin resin film. The TAC film and the cyclic olefin resin film are preferably manufactured by extrusion or casting and do not involve stretching during film formation. As a result, residual stress is small, making it possible to achieve the desired shrinkage rate described above.

[0032] In the polarizing plate with a phase difference layer according to an embodiment of the present invention, the protective layer 12 is typically positioned on the viewing side of an image display device. Therefore, the protective layer 12 may be subjected to surface treatments such as hard coat (HC) treatment, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment as needed. Furthermore, the protective layer 12 may be subjected to treatments that improve visibility when viewed through polarized sunglasses (typically, by providing (elliptic) circular polarization function or providing ultra-high phase difference) as needed. By applying such treatments, excellent visibility can be achieved even when viewing the display screen through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with a phase difference layer can be suitably applied to image display devices that may be used outdoors.

[0033] The thickness of the 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 protective layer includes the thickness of the surface treatment layer.

[0034] In one embodiment, the second protective layer is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0035] D. First retardation layer D-1. Characteristics of the first phase difference layer The in-plane phase difference Re(550) of the first phase difference layer 21 is 100 nm to 200 nm, preferably 110 nm to 180 nm, more preferably 120 nm to 160 nm, and even more preferably 130 nm to 150 nm, as described above. That is, the first phase difference layer can function as a so-called λ / 4 plate.

[0036] The first 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 first 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 first retardation layer is, for example, greater 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.

[0037] Since the first retardation layer has an in-plane retardation as described above, it has a relationship of nx > ny. As long as the first retardation layer has a relationship of nx > ny, it exhibits any appropriate refractive index characteristics. The refractive index characteristics of the first retardation layer typically exhibit 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 first 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 a polarizing plate with a retardation layer is used in an image display device, a very excellent reflected hue can be achieved.

[0038] The thickness of the first 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 70 μm, more preferably 20 μm to 60 μm, and most preferably 20 μm to 50 μm.

[0039] When the first retardation layer is heated at 80°C to 125°C for up to 180 minutes, the shrinkage rate in the slow axis direction is, for example, 4% or less, preferably 3.5% or less, and more preferably 3% or less. The smaller the shrinkage rate, the more preferable it is, and the lower limit can be, for example, 0.5%. If the shrinkage rate of the first retardation layer is within such a range, cracks in a harsh high-temperature and high-humidity environment can be better suppressed.

[0040] The elongation at break of the stretched film constituting the first retardation layer is preferably 200% or more, more preferably 210% or more, still more preferably 220% or more, and particularly preferably 245% or more. The upper limit of the elongation at break can be, for example, 500%. If the elongation at break of the stretched film constituting the first retardation layer is within such a range, cracks in a harsh high-temperature and high-humidity environment can be better suppressed by the synergistic effect with the effect of the above shrinkage rate. In this specification, the "elongation at break" means the elongation rate when the film breaks in uniaxial stretching with a fixed end at a predetermined stretching temperature (for example, Tg - 2°C).

[0041] The absolute value of the photoelastic coefficient of the first 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 still more preferably 2.0×10 -12 (m 2 / N) to 12×10 -12 (m 2 / N). If the absolute value of the photoelastic coefficient is within such a range, display unevenness can be suppressed when the polarizing plate with a retardation layer is applied to an image display device.

[0042] D-2. Constituent Materials of the First Retardation Layer The first phase difference layer typically contains a resin that includes at least one bonding group selected from the group consisting of carbonate bonds and ester bonds. In other words, the first phase difference layer contains a polycarbonate resin, a polyester resin, or a polyester carbonate resin (hereinafter, these may be collectively referred to simply as polycarbonate resins).

[0043] In one embodiment, the polycarbonate resin comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanol, di, tri, or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, structural units derived from alicyclic dimethanol, and / or structural units derived from di, tri, or polyethylene glycol; more preferably, it comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from di, tri, or polyethylene glycol. The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. Further details regarding polycarbonate resins suitably used in the present invention are described, for example, in Japanese Patent Publication No. 2014-10291, Japanese Patent Publication No. 2014-26266, Japanese Patent Publication No. 2015-212816, Japanese Patent Publication No. 2015-212817, and Japanese Patent Publication No. 2015-212818, and such descriptions are incorporated herein by reference.

[0044] In one embodiment, the polycarbonate resin includes at least one structural unit selected from the group consisting of structural units represented by the above general formula (1) and / or structural units represented by the above general formula (2). These structural units are derived from divalent oligofluorene and may hereafter be referred to as oligofluorene structural units. Such polycarbonate resin has positive refractive index anisotropy.

[0045] In one embodiment, the first phase difference layer may further contain an acrylic resin. The acrylic resin content is typically 0.5% by mass to 1.5% by mass. In this specification, a percentage or part in "mass" is synonymous with a percentage or part in "weight" units.

[0046] In one embodiment, the first phase difference layer may further contain an antioxidant. Any suitable compound can be used as the antioxidant. Specific examples include pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: trade name "Irganox 1010" (manufactured by BASF), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene: trade name "Irganox 1330" (manufactured by BASF), and tris(3,5-di-tert-butyl-4-hydroxybenzyl) Isocyanurate: Trade name "Irganox 3114" (manufactured by BASF), Stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: Trade name "Irganox 1076" (manufactured by BASF), 2,2'-Thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: Trade name "Irganox 1035" (manufactured by BASF), N,N'-Hexamethylenebis[3-(3,5 -di-tert-butyl-4-hydroxyphenyl)propanamide]: trade name "Irganox 1098" (manufactured by BASF), bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)]: trade name "Irganox 245" (manufactured by BASF), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] trade name " Examples include "Irganox 259" (manufactured by BASF), 4-[[4,6-bis(octylthio)-1,3,5-triazine-2-yl]amino]-2,6-di-tert-butylphenol: trade name "Irganox 565" (manufactured by BASF), and 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol: trade name "ADEKA LA-31" (manufactured by ADEKA). The antioxidant content is typically 1.5% to 3.5% by mass.

[0047] D-2-1. Polycarbonate resin <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 Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C4-C10 aryl group, a substituted or unsubstituted C1-C10 acyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C1-C10 aryloxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C10 vinyl group, a substituted or unsubstituted C1-C10 ethynyl group, a substituted sulfur atom, a substituted silicon atom, a halogen atom, a nitro group, or a cyano group. 4 ~R 9 They may be the same or different from each other, R 4 ~R 9 At least two adjacent groups may be bonded to each other to form a ring.

[0048] The content of oligofluorene structural units in polycarbonate resins is preferably 1% to 40% by mass, more preferably 10% to 35% by mass, even more preferably 15% to 30% by mass, and particularly preferably 18% to 25% by mass, relative to the total resin content. If the content of oligofluorene structural units is too high, problems such as excessively high photoelastic coefficients, insufficient reliability, and insufficient phase difference expression may occur. Furthermore, because the proportion of oligofluorene structural units in the resin becomes high, the range of molecular design becomes narrower, and it may become difficult to improve the resin when modification is required. On the other hand, even if the desired inverse dispersion wavelength dependence can be obtained with a very small amount of oligofluorene structural units, in this case, the optical properties change sensitively in response to slight variations in the content of oligofluorene structural units, making it difficult to manufacture the resin so that various properties fall within a certain range.

[0049] Details of the oligofluorene structural units are described, for example, in International Publication No. 2015 / 159928, which is incorporated herein by reference.

[0050] <Other structural units> Polycarbonate resins 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 inverse dispersion wavelength properties, it is necessary to incorporate structural units having positive intrinsic birefringence into the polymer structure along with oligofluorene structural units having negative intrinsic birefringence. Therefore, dihydroxy compounds or diester compounds that serve as raw materials for structural units having positive birefringence are even more preferred as other monomers for copolymerization.

[0051] Examples of copolymer monomers include compounds into which a structural unit containing an aromatic ring can be introduced, and compounds that do not incorporate a structural unit containing an aromatic ring, i.e., compounds composed of an aliphatic structure.

[0052] Specific examples of compounds composed of the aforementioned aliphatic structure are listed below: 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. Examples of alicyclic hydrocarbon secondary and tertiary alcohols include dihydroxy compounds such as 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc.; 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2,6-decali Dihydroxy compounds, which are primary alcohols of alicyclic hydrocarbons, are exemplified by dihydroxy compounds derived from terpene compounds such as dimethyl dimethyl, 1,5-decalindimethanol, 2,3-decalindimethanol, 2,3-norbornanedimethanol, 2,5-norbornanedimethanol, 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.

[0053] Specific examples of compounds into which the aforementioned aromatic ring-containing structural unit can be introduced are listed below: 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl )methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(4-hydroxyphenyl) 2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenylsulfone, bis(4-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.

[0054] Furthermore, while 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, depending on the manufacturing 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.

[0055] As copolymer 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 have been conventionally known as compounds having a structural unit with negative birefringence, as well as dicarboxylic acid compounds having a fluorene ring, can also be used in combination with oligofluorene compounds.

[0056] The resin used in the embodiments of the present invention preferably contains, among the structural units that can be introduced by the compound having the alicyclic structure, a structural unit represented by the following formula (3) as a copolymer component. [ka]

[0057] Spiroglycol can be used as a dihydroxy compound to which the structural unit of formula (3) can be introduced.

[0058] In the resin used in the embodiments of 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. If the content of the structural unit represented by formula (3) is above 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. In addition, since the polymerization reaction rate of spiroglycol is relatively slow, the polymerization reaction can be easily controlled by keeping the content below the upper limit.

[0059] The resin used in the embodiments of the present invention preferably further contains a structural unit represented by the following formula (4) as a copolymer component. [ka]

[0060] Examples of dihydroxy compounds into which the structural unit represented by formula (4) can be introduced include isosorbide (ISB), isomannide, and isoidette, which are stereoisomers of each other. These may be used individually or in combination of two or more.

[0061] In the resin used in the embodiments of the present invention, it is preferable that the structural unit represented by formula (4) is 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. If the content of the structural unit represented by formula (4) is above the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Furthermore, since the structural unit represented by formula (4) has the characteristic of high water absorption, if the content of the structural unit represented by formula (4) is below the upper limit, the dimensional change of the molded article due to water absorption can be kept within an acceptable range.

[0062] The resin used in the embodiments of 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, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, and 1,4-cyclohexanedicarboxylic acid (and their derivatives) are more preferably used, with 1,4-cyclohexanedimethanol and tricyclodecanedimethanol being particularly preferred. Resins containing structural units derived from these monomers have an excellent balance of optical properties, heat resistance, mechanical properties, etc. 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 improving reaction efficiency.

[0063] The glass transition temperature (Tg) of the resin used in the embodiments of the present invention is preferably 110°C or higher and 160°C or lower. The upper limit is more preferably 155°C or lower, even 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, the heat resistance tends to deteriorate, which may cause dimensional changes after film formation or worsen the reliability of the quality under the usage conditions of the first phase difference layer. 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, its stretchability may deteriorate, and the transparency of the film may be impaired.

[0064] D-2-2. Acrylic resin Acrylic resins used are thermoplastic acrylic resins. Examples of monomers that form the structural units of acrylic resins include the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, 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)acroyloxyethyl succinate, 2-(meth)acroyloxyethyl maleate, 2-(meth)acroyloxyethyl 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, cyclododecyl acrylate. These may be used individually or in combination of two or more types. Forms using two or more monomers in combination include copolymerization of two or more monomers, blends of two or more homopolymers of one monomer, and combinations thereof. Furthermore, other monomers copolymerizable with these acrylic monomers (e.g., olefin monomers, vinyl monomers) may be used in combination.

[0065] The acrylic resin contains structural units derived from methyl methacrylate. The content of structural units derived from methyl methacrylate in the acrylic resin is preferably 70% by mass or more and 100% by mass or less. The lower limit is more preferably 80% by mass or more, 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, it is preferable to use methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene. Thermal stability can be improved by copolymerizing methyl acrylate. By using phenyl (meth)acrylate, benzyl (meth)acrylate, and styrene, the refractive index of the acrylic resin can be adjusted, and by matching it to the refractive index of the resin to be combined with, the transparency of the resulting resin composition can be improved. By using such an acrylic resin, an inverse dispersion phase difference film with excellent stretchability and phase difference expression, and low haze can be obtained.

[0066] The weight-average molecular weight (Mw) of the acrylic resin is between 10,000 and 200,000. The lower limit is preferably 30,000 or higher, and particularly preferably 50,000 or higher. The upper limit is preferably 180,000 or lower, and particularly preferably 150,000 or lower. Within this molecular weight range, compatibility with polycarbonate resins is achieved, improving the transparency of the final phase difference film (phase difference layer) and significantly improving the stretchability during stretching. The above weight-average molecular weight is measured by GPC and is the molecular weight in polystyrene equivalent. Furthermore, from the viewpoint of compatibility, it is preferable that the acrylic resin substantially does not contain branched structures. The absence of branched structures can be confirmed by the unimodal GPC curve of the acrylic resin.

[0067] D-2-3. Blend of polycarbonate resin and acrylic resin When polycarbonate resin and acrylic resin are used in combination, the polycarbonate resin and acrylic resin are blended and used as a resin composition for manufacturing a phase difference film (first phase difference layer) (the manufacturing method will be described later in section D-3). The polycarbonate resin and acrylic resin can preferably be blended in a molten state. A typical 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 falls below 200°C, the resin viscosity may become too high, placing an excessive load on the extruder, or the resin may not melt sufficiently. Furthermore, any suitable configuration can be adopted for the extruder, screw configuration, etc. It is preferable to use a twin-screw extruder to obtain resin transparency suitable for optical film applications. Additionally, since residual low-molecular-weight components in the resin and low-molecular-weight thermal decomposition components during extrusion mixing may contaminate the cooling rolls and conveyor rolls during the film-forming and stretching processes, it is preferable to use an extruder equipped with a vacuum vent to remove these components.

[0068] The acrylic resin content in the resin composition (and consequently, the first phase difference layer) is 0.5% by mass or more and 2.0% by mass or less, as described above. A lower limit of 0.6% by mass or more is more preferable. An upper limit of 1.5% by mass or less is preferable, 1.0% by weight or less is more preferable, 0.9% by weight or less is even more preferable, and 0.8% by mass or less is particularly preferable. In this way, by blending acrylic resin with polycarbonate resin in a very limited ratio, the stretchability and phase difference expression can be significantly increased. Furthermore, haze can be suppressed. Such effects are not theoretically clear and are unexpected excellent effects obtained through trial and error. Note that if the acrylic resin content is too low, the above effects may not be obtained. On the other hand, if the acrylic resin content is too high, haze may increase. Also, stretchability and phase difference expression may be insufficient or even decrease compared to when within the above range.

[0069] The resin composition may be further blended with synthetic resins such as aromatic polycarbonates, aliphatic polycarbonates, aromatic polyesters, aliphatic polyesters, polyamides, polystyrene, polyolefins, acrylics, amorphous polyolefins, ABS, AS, polylactic acid, polybutylene succinate, rubber, and combinations thereof, for the purpose of modifying properties such as mechanical properties and / or solvent resistance.

[0070] The resin composition may further contain additives. Specific examples of additives include heat stabilizers, antioxidants, catalyst deactivators, ultraviolet absorbers, light stabilizers, mold release agents, dyes and pigments, impact modifiers, antistatic agents, lubricants, plasticizers, compatibilizers, nucleating agents, flame retardants, inorganic fillers, and foaming agents. The types, number, combinations, and content of additives included in the resin composition can be appropriately determined depending on the purpose.

[0071] D-3. Method for forming the first phase difference layer The first phase difference layer is obtained by forming a film from the polycarbonate resin (or resin composition when an acrylic resin is used in combination) described in section D-2 above, and then stretching the film. Any suitable molding method can be used to form the film. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, cast coating (e.g., casting), calendering, and hot pressing. Among these, extrusion molding or cast coating is preferred because it enhances the smoothness of the resulting film and provides good optical uniformity. Since problems may arise due to residual solvent in the cast coating method, extrusion molding, and especially melt extrusion molding using a T-die, is preferred from the viewpoint of film productivity and ease of subsequent stretching. The molding conditions can be appropriately set according to the composition and type of resin used, the desired properties of the first phase difference layer, etc. In this way, a resin film containing a polycarbonate resin and, if necessary, an acrylic resin can be obtained.

[0072] The thickness of the resin film (unstretched film) can be set to any appropriate value depending on the desired thickness of the first phase difference layer obtained, the desired optical properties, the stretching conditions described later, etc. Preferably, it is 50 μm to 300 μm.

[0073] The stretching described above can be carried out using any appropriate stretching method and conditions (e.g., stretching temperature, stretching ratio, stretching direction). Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinking, and fixed-end shrinking can be used individually, simultaneously, or sequentially. Regarding the stretching direction, it can be carried out in various directions and dimensions, such as the length direction, width direction, thickness direction, and diagonal direction.

[0074] By appropriately selecting the stretching method and stretching conditions described above, a phase difference layer having the desired optical properties (e.g., refractive index properties, in-plane phase difference, Nz coefficient) can be obtained.

[0075] In one embodiment, the stretching temperature of the above film is preferably between the glass transition temperature (Tg) of the polycarbonate resin and Tg+30°C, more preferably between Tg and Tg+15°C, and most preferably between Tg and Tg+10°C. When an acrylic resin is used in combination, the stretching temperature is below Tg. Normally, when stretching a polycarbonate resin film, stretching is practically impossible at temperatures below Tg because the film is in a glassy state. On the other hand, by incorporating a small amount of acrylic resin (typically polymethyl methacrylate), stretching below Tg becomes possible without substantially changing the Tg of the polycarbonate resin. Furthermore, although not theoretically clear, stretching below Tg makes it possible to realize an inverse dispersion phase difference film (first phase difference layer) with excellent stretchability and phase difference expression, and 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. However, the above film can be appropriately stretched even at temperatures higher than Tg, such as up to approximately Tg+5°C or, for example, Tg+2°C.

[0076] The stretched film obtained as described above is subjected to a heat treatment, if necessary, by heating at a temperature of 105°C or higher for 2 minutes or more. By performing the heat treatment, a first phase difference layer having the desired shrinkage rate can be formed. The heating temperature is preferably 105°C to 140°C, more preferably 110°C to 130°C, and even more preferably 115°C to 125°C. The heating time is preferably 2 minutes to 150 minutes, more preferably 3 minutes to 120 minutes, and even more preferably 5 minutes to 60 minutes.

[0077] If necessary, the stretched film may be subjected to a relaxation treatment. This can relieve the stress caused by stretching and form a phase difference layer having the desired shrinkage rate. Any suitable conditions can be used for the relaxation treatment. For example, the stretched film may be shrunk along the stretching direction at a predetermined relaxation temperature and a predetermined relaxation rate (shrinkage rate). The relaxation temperature is preferably 60°C to 150°C. The relaxation rate is preferably 3% to 6%. If a relaxation treatment is performed, it can typically be performed before the heat treatment described above.

[0078] In this way, a phase difference film constituting the first phase difference layer can be obtained.

[0079] E. Second retardation layer As described above, the second phase difference layer may be a so-called positive C plate whose refractive index characteristics exhibit the relationship nz > nx = ny. By using a positive C plate as the second phase difference layer, reflections in oblique directions can be effectively prevented, and the anti-reflective function can be widened to a wider viewing angle. In this case, the phase difference Rth(550) in the thickness direction of the second phase difference layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, even more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. Here, "nx = ny" includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. That is, the in-plane phase difference Re(550) of the second phase difference layer may be less than 10 nm.

[0080] A second phase difference layer having the refractive index characteristic nz>nx=ny can be formed from any suitable material. Preferably, the second phase difference layer consists of a film containing a liquid crystal material fixed to a homeotropic orientation. The liquid crystal material (liquid crystal compound) that can be homeotropically oriented may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the phase difference layer are described in paragraphs

[0020] to

[0028] of Japanese Patent Application Publication No. 2002-333642. In this case, the thickness of the second phase difference layer is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

[0081] F. First and second layers (heat-resistant and moisture-resistant layers) The first layer 31 and the second layer 32 can each employ any suitable configuration as long as they satisfy the above-mentioned shear fracture strength. Furthermore, the first layer 31 and the second layer 32 may have the same configuration or different configurations. As described above, by providing the first layer, or the first layer and the second layer, a polarizing plate with a phase difference layer that has excellent durability even in harsh high-temperature and high-humidity environments can be realized. Hereinafter, the first layer 31 and the second layer 32 will be described together as a heat-resistant and moisture-resistant layer.

[0082] The heat-resistant and moisture-resistant layer is preferably substantially optically isotropic. The in-plane phase difference Re(550) of the heat-resistant and moisture-resistant layer is preferably 0nm to 10nm, more preferably 0nm to 5nm, even more preferably 0nm to 3nm, and particularly preferably 0nm to 2nm. The phase difference Rth(550) in the thickness direction of the heat-resistant and moisture-resistant layer is preferably -10nm to +10nm, more preferably -5nm to +5nm, even more preferably -3nm to +3nm, and particularly preferably -2nm to +2nm. If Re(550) and Rth(550) of the heat-resistant and moisture-resistant layer are within these ranges, adverse effects on display characteristics can be prevented when applied to an image display device.

[0083] The light transmittance at 380 nm in a 3 μm thick heat-resistant and moisture-resistant layer is preferable as high as possible. Specifically, the light transmittance is preferably 85% or higher, more preferably 88% or higher, and even more preferably 90% or higher. If the light transmittance is within this range, the desired transparency can be ensured. The light transmittance can be measured, for example, by a method in accordance with ASTM-D-1003.

[0084] The haze of the heat-resistant and moisture-resistant layer should be as low as possible. Specifically, the haze is preferably 5% or less, more preferably 3% or less, even more preferably 1.5% or less, and particularly preferably 1% or less. When the haze is 5% or less, the polarizing plate with the phase difference layer can be given good clarity. As a result, the display content of the image display device can be clearly seen.

[0085] In one embodiment, the adhesion between the heat-resistant and moisture-resistant layer and the first phase difference layer is preferable as much as possible. Specifically, the adhesion is preferably 2 points or less, more preferably 1 point or less, and particularly preferably 0 points in the grid peel test described in JIS K 5600-5-6. When the adhesion is 2 points or less in the grid peel test, peeling of the polarizing plate with the phase difference layer in a harsh high-temperature and high-humidity environment can be well suppressed, and problems related to appearance such as peeling during rework can be suppressed.

[0086] As described above, the heat-resistant and moisture-resistant layer is typically a cured or solidified layer of resin. The cured layer may be, for example, a thermosetting resin, an active energy ray curable resin, or a cured layer of an active energy ray curable resin. Specific examples of cured layers include a simple cured layer, a hard coat layer, an adhesive layer composed of an active energy ray curable adhesive, and a crosslinked layer using a crosslinking agent. The solidified layer may be, for example, a solidified layer of a coating film of a thermoplastic resin in an organic solvent solution. These may constitute the heat-resistant and moisture-resistant layer individually, or two or more may be combined to form the heat-resistant and moisture-resistant layer.

[0087] (Hard coat layer) The hard coat layer (essentially, the composition forming the hard coat layer) contains a curing component and, typically, a photopolymerization initiator. A typical example of the curing component is active energy ray-curable (meth)acrylate. Examples of active energy ray-curable (meth)acrylate include ultraviolet-curable (meth)acrylate and electron beam-curable (meth)acrylate. Preferably, ultraviolet-curable (meth)acrylate is used because it allows for efficient formation of the hard coat layer with simple processing operations. The ultraviolet-curable (meth)acrylate includes ultraviolet-curable monomers, oligomers, polymers, etc. The ultraviolet-curable (meth)acrylate includes monomer components and oligomer components having preferably two or more, more preferably three to six, ultraviolet polymerization functional groups. Specific examples of ultraviolet-curable (meth)acrylate include urethane acrylate, pentaerythritol triacrylate, ethoxylated glycerin triacrylate, and polyether urethane diacrylate. In addition to these, curing components of active energy ray-curable adhesives described later may also be used. The curing component may be used alone or in combination of two or more. The curing method may be radical polymerization or cationic polymerization. In one embodiment, an organic-inorganic hybrid material may be used, which is a compound of (meth)acrylate with silica particles or a polysilsesquioxane compound. The constituent materials and formation method of the hard coat layer are described, for example, in Japanese Patent Publication No. 2011-237789, Japanese Patent Publication No. 2020-064236, Japanese Patent Publication No. 2010-152331, etc. The descriptions in these publications are incorporated herein by reference. In this specification, "(meth)acrylic" means acrylic and / or methacrylic. Also, (meth)acrylic may be simply referred to as acrylic.

[0088] (Active energy ray curing adhesive) Examples of active energy ray curing adhesives include ultraviolet curing adhesives and electron beam curing adhesives. From the perspective of curing mechanism, examples of active energy ray curing adhesives include radical curing type, cationic curing type, anionic curing type, and hybrids of radical curing type and cationic curing type.

[0089] Adhesives, like compositions that form a hard coat layer, typically contain a curing component and a photopolymerization initiator. Typical curing components include monomers and / or oligomers having functional groups such as (meth)acrylate groups and (meth)acrylamide groups. Specific examples of curing components include tripropylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, tricyclodecanedimethanol diacrylate, phenoxydiethylene glycol acrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, EO-modified diglycerin tetraacrylate, γ-butyrolactone acrylate, polyethylene glycol diacrylate, and hydroxyl dimethylolpropane triacrylate. Examples of suitable adhesives include neopentyl glycol acrylic acid adducts of roxypivalate, acryloyl morpholine, unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone, N-methylpyrrolidone, diethylacrylamide, hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate, neopentyl glycol glycidyl ether, and dicyclopentadiene-type epoxy resins. As curing components, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 4-hydroxybutyl acrylate, neopentyl glycol diacrylate, isocyanuric acid EO-modified triacrylate, etc., may also be used. In addition to these, the above-mentioned hard coat layer curing components may also be used. The curing components may be used alone or in combination of two or more. The adhesive may further contain oligomer components in addition to the above-mentioned curing components. By using oligomer components, the viscosity of the adhesive before curing can be reduced and its operability can be improved. Typical examples of oligomer components include (meth)acrylic oligomers and polyurethane-based (meth)acrylic oligomers.

[0090] (Crosslinked layer due to crosslinking agent) The crosslinked layer (substantially, the composition forming the crosslinked layer) comprises a curing component and a crosslinking agent. Examples of curing components include those described above with respect to hard coat layers and active energy ray curing adhesives. The crosslinking agent may be a thermal crosslinking agent or a photocrosslinking agent. That is, the crosslinked layer may be a thermal crosslinked layer or a photocrosslinked layer. Examples of thermal crosslinking agents 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. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of photocrosslinking agents include photoacid generators. Examples of photoacid generators include organic peroxides. The thermal crosslinking agent or the photocrosslinking agent may be used individually or in combination of two or more.

[0091] (Cured layer of thermosetting resin) Any suitable thermosetting resin can be used as the thermosetting resin, as long as the cured layer has the desired storage modulus. Typical examples of thermosetting resins include epoxy resins, (meth)acrylic resins, unsaturated polyester resins, polyurethane resins, alkyd resins, melamine resins, urea resins, and phenolic resins. For example, oxetane compounds (monomers, oligomers, polymers) may be added to the thermosetting resin.

[0092] (solidified layer) As described above, the solidified layer may be, for example, a solidified layer of a coating film of an organic solvent solution of a thermoplastic resin. As the thermoplastic, any suitable thermoplastic resin can be used as long as the solidified layer has the desired storage modulus. Typical examples of thermoplastic resins include (meth)acrylic resins and epoxy resins.

[0093] The (meth)acrylic resin has a glass transition temperature (Tg) preferably of 100°C to 220°C, more preferably of 110°C to 200°C, and even more preferably of 120°C to 160°C. The (meth)acrylic resin may have repeating units containing a ring structure. Examples of repeating units containing a ring structure include lactone ring units, glutaric acid anhydride units, glutarimide units, maleic acid anhydride units, and maleimide (N-substituted maleimide) units. Only one type of repeating unit containing a ring structure may be included in the repeating units of the (meth)acrylic resin, or two or more types may be included. The (meth)acrylic resin may be a copolymer of a (meth)acrylic monomer and a boron-containing monomer (boron-containing (meth)acrylic resin). The boron-containing (meth)acrylic resin may have repeating units containing the ring structure described above.

[0094] Preferably, an epoxy resin having an aromatic ring is used as the epoxy resin. By using an epoxy resin having an aromatic ring, the adhesion between the solidified layer and the first phase difference layer can be improved. Examples of epoxy resins having an aromatic ring include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol; naphthol type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin. Preferably, bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin are used. Only one type of epoxy resin may be used, or two or more types may be used in combination.

[0095] Any suitable organic solvent capable of dissolving or uniformly dispersing the thermoplastic resin can be used as the organic solvent. Specific examples of organic solvents include ethyl acetate, toluene, methylethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.

[0096] The resin concentration in the organic solvent solution is preferably 3 to 20 parts by weight per 100 parts by weight of solvent. With such a resin concentration, a uniform coating film that adheres closely to the first phase difference layer can be formed.

[0097] The thickness of the heat-resistant and moisture-resistant layer is preferably 500 nm to 5 μm, more preferably 800 nm to 4 μm, and even more preferably 1 μm to 3 μm. Even with such a thin thickness, a polarizing plate with a phase difference layer can be realized that has excellent durability even in harsh high-temperature and high-humidity environments. If the thickness of the heat-resistant and moisture-resistant layer is too thin, it may be difficult to form the layer itself, or even if it is formed, its effect may be insufficient. If the thickness of the heat-resistant and moisture-resistant layer is too thick, curling due to curing shrinkage may occur, making it difficult to form the layer itself, or it may not cure sufficiently, causing the heat-resistant and moisture-resistant layer to function as a weak layer.

[0098] A heat-resistant and moisture-resistant layer is typically formed by applying a composition that forms the heat-resistant and moisture-resistant layer to a first phase difference layer and curing or solidifying the coated film. Specifically, the first layer is formed by applying the layer-forming composition to the second main surface of the first phase difference layer and curing or solidifying the coated film; the second layer (if present) is formed by applying the layer-forming composition to the first main surface of the first phase difference layer and curing or solidifying the coated film. If the heat-resistant and moisture-resistant layer is an active energy ray curing layer, the coated film can be cured by irradiating it with active energy rays (e.g., visible light, ultraviolet light, electron beams). If the heat-resistant and moisture-resistant layer is a thermosetting layer, the coated film can be cured by heating it. If the heat-resistant and moisture-resistant layer is a solidification layer, the coated film can be solidified by heating it.

[0099] The surface on which the heat-resistant and moisture-resistant layer is formed (for example, the surface of the first phase difference layer) may be surface-modified beforehand. Specifically, the surface energy of the surface may be increased by surface modification. Surface modification can, for example, adjust the shear fracture strength of the resulting heat-resistant and moisture-resistant layer. It can also improve the adhesion between the heat-resistant and moisture-resistant layer and the first phase difference layer. Surface modification can be performed, for example, by corona treatment or plasma treatment. These may be used alone or in combination.

[0100] G. Image display device The polarizing plate with a phase difference layer described above can be applied to an image display device. Therefore, embodiments of the present invention also include image display devices using such a polarizing plate with a phase difference layer. Typical examples of image display devices include liquid crystal display devices and organic EL display devices. An image display device according to an embodiment of the present invention typically includes the polarizing plate with a phase difference layer described in items A to F above on its viewing side. [Examples]

[0101] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The thickness is the value measured by the measurement method described below. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. <Thickness> Thicknesses of 10 μm or less were measured using a scanning electron microscope (JEOL Ltd., product name "JSM-7100F"). Thicknesses exceeding 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C").

[0102] [Example 1] (Fabrication of polarizing plates) As a thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length with a Tg of approximately 75°C was used, and one side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizers were immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final transmittance (Ts) of the polarizers obtained would be the desired value (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4% by weight, potassium iodide concentration 5% by weight) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the material was dried in an oven maintained at approximately 90°C while being brought into contact with a SUS (stainless steel) heated roll whose surface temperature was maintained at approximately 75°C (drying shrinkage treatment). In this way, a polarizer with a thickness of approximately 5 μm was formed on the resin substrate.

[0103] An HC-TAC film was laminated to the surface of the obtained polarizer (the side opposite to the resin substrate) via an ultraviolet-curing adhesive as a protective layer on the viewing side. The HC-TAC film is a triacetylcellulose (TAC) film (25 μm thick) with a hard coat layer (7 μm thick) formed on it, and it was laminated so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off to obtain a polarizer plate having the HC-TAC film / polarizer configuration. The HC-TAC film had a shrinkage rate of 0.03% after being left in an environment of 85°C for 240 hours.

[0104] (Fabrication of the phase difference film constituting the first phase difference layer) Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻² parts by mass (6.78 × 10⁻⁵ mol) of calcium acetate monohydrate as a catalyst were charged. After purging the reactor with reduced pressure nitrogen, it was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the process to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was directed to a 100°C reflux condenser, and the monomer components contained in the phenol vapor were returned to the reactor. The uncondensed phenol vapor was then directed to a 45°C condenser for recovery. Nitrogen was introduced into the first reactor to restore pressure to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and depressurization in the second reactor were started, and the internal temperature reached 240°C and the pressure 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate resin was extruded into water. The strands were then cut to obtain pellets.

[0105] The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours. Then, a long resin film with a thickness of 135 μm was produced using a film-making apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120~130°C), and a winding machine. The obtained long resin film was stretched in the width direction at a stretching temperature of 133°C and a stretching ratio of 2.8 times to obtain a phase difference film with a thickness of 48 μm. The Re(550) of the obtained phase difference film was 141 nm, the Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12.

[0106] (Fabrication of the liquid crystal alignment solidification layer constituting the second phase difference layer) A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (I) (the numbers 65 and 35 in the formula indicate the mole percent of monomer units and are conveniently represented as a block polymer: weight-average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals: trade name Irgacure 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a vertically aligned PET substrate using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. By irradiating this liquid crystal layer with ultraviolet light to cure the liquid crystal layer, a liquid crystal alignment solidified layer (thickness 3 μm) exhibiting the refractive index characteristic nz>nx=ny was formed on the substrate. [ka]

[0107] (Preparation of UV-curing adhesive 1) 5 parts of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-303"), 35 parts of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 24 parts of neopentyl glycol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate NP-A"), 10 parts of isocyanuric acid EO-modified triacrylate (manufactured by Toagosei Co., Ltd., product name "Aronics M-315"), 5 parts of pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-TMM-3LM-N"), 15 parts of polyurethane-based acrylic oligomer (manufactured by Mitsubishi Chemical Corporation, product name "UV3000B"), and photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad"). UV-curing adhesive 1 was prepared by combining 3 parts of (184), 2 parts of a photopolymerization initiator (manufactured by Sunapro, product name "CPI-100P"), and 1 part of boric acid (manufactured by Fujifilm Wako Pure Chemical Industries).

[0108] (Fabrication of polarizing plates with phase difference layer) The liquid crystal alignment solidification layer was bonded to one side of the above-mentioned phase difference film using the above-mentioned ultraviolet-curing adhesive 1. Specifically, the ultraviolet-curing adhesive was applied to the phase difference film so that the thickness after curing would be 1 μm, and the integrated light intensity was 900 mJ / cm² under a nitrogen atmosphere. 2 The film was cured by irradiating it with ultraviolet light, and the liquid crystal alignment solidification layer was bonded to one side of the phase difference film via an adhesive layer. Next, the polarizing plate was bonded to the other side of the phase difference film via a 5 μm thick acrylic adhesive layer, thereby obtaining a polarizing plate with a phase difference layer.

[0109] [Example 2] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the coated surface of the phase difference film was subjected to corona treatment beforehand when applying the UV-curing adhesive to the phase difference film.

[0110] [Example 3] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the phase difference film was coated with the hard coat layer shown below before bonding the polarizing plate to the phase difference film.

[0111] (Preparation of the hard coat layer) A hard coat layer-forming composition was prepared by diluting 13 parts of urethane acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Oligo UA-53H"), 17 parts of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #300"), 70 parts of ethoxylated glycerin triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-GLY-9E"), and 3 parts of photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad 907") in a cyclopentanone / toluene mixed solvent. This hard coat layer-forming composition was applied to a phase difference film using a wire bar to a cured thickness of 2 μm, heated at 60°C for 1 minute, and then subjected to an integrated light intensity of 250 mJ / cm² under a nitrogen atmosphere. 2 By irradiating with ultraviolet light in this manner, a hard coat layer (HC layer) with a thickness of 2 μm was formed.

[0112] [Example 4] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 2, except that the above-mentioned HC layer was provided on the phase difference film before laminating the polarizing plate to the phase difference film.

[0113] [Example 5] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the above-mentioned HC layer was provided on the phase difference film before laminating the liquid crystal alignment solidification layer to the phase difference film, the liquid crystal alignment solidification layer was laminated using the ultraviolet curing adhesive 2 shown below instead of ultraviolet curing adhesive 1, and the above-mentioned HC layer was provided on the phase difference film before laminating the polarizing plate to the phase difference film.

[0114] (Preparation of UV-curing adhesive 2) UV-curing adhesive 2 was prepared by blending 53.3 parts of unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone (manufactured by Daicel Corporation, product name "Praxel FA-1DDM"), 6.7 parts of polyethylene glycol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Acrylate 9EG-A"), 26.7 parts of acryloyl morpholine, 13.3 parts of acrylic polymer (manufactured by Toagosei Co., Ltd., product name "ARUFON UP-1190"), 3 parts of photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad 907"), and 3 parts of photopolymerization initiator (manufactured by Nippon Kayaku Co., Ltd., product name "KAYACURE-DETX-S").

[0115] [Comparative Example 1] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the above-mentioned UV-curing adhesive 2 was used instead of UV-curing adhesive 1 to bond the liquid crystal alignment solidification layer.

[0116] [Comparative Example 2] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the above-mentioned HC layer was provided on the phase difference film before laminating the liquid crystal alignment solidification layer to the phase difference film, and the liquid crystal alignment solidification layer was laminated using the ultraviolet curing adhesive 2 shown below instead of ultraviolet curing adhesive 1.

[0117] [Comparative Example 3] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that the liquid crystal alignment solidification layer was bonded using the UV-curing adhesive 2 instead of the UV-curing adhesive 1, and the HC layer was provided on the phase difference film before bonding the polarizing plate to the phase difference film.

[0118] The following evaluations were performed on each example and comparative example. The evaluation results are summarized in Table 1. <Rating> 1. Shear failure strength For each example and comparative example, the shear fracture strength of the layers (first layer and second layer) formed on the surface of the phase difference film was measured using the "SAICAS EN" oblique cutting device manufactured by Daipla Wintes Co., Ltd. The cutting edge used for oblique cutting had a blade width of 1 mm, a rake angle of 20°, and a relief angle of 10°. The measurements were performed at 23°C in constant speed mode (horizontal speed of the cutting edge of 10 μm / sec, vertical speed of 0.1 μm / sec). The shear failure strength FS (MPa) can be calculated using the following formula from the horizontal force FH acting on the cutting edge during oblique cutting of the layer to be measured, the area D of the shear surface, and the shear angle θ. During the oblique cutting process of the layer to be measured, the maximum value of FS shown in the region from 30% to 70% depth from the surface on the cutting side (the surface opposite to the phase difference film) was taken as the shear failure strength of each layer. FS = (FH / 2D)cotθ 2. HAST test The resulting polarizing plates with phase difference layers were subjected to a HAST test, an accelerated durability test under high temperature and high humidity conditions. The HAST test was conducted in accordance with JIS C60068. Specifically, the polarizing plates with phase difference layers were heated and humidified in an oven controlled at 110°C and 85%RH for 36 hours. The condition of the polarizing plates with phase difference layers after heating and humidification was visually observed and evaluated according to the following criteria. The results are shown in Table 1. Good: No cracks or peeling were observed. Acceptable: Minor cracks or peeling observed. Defect: Significant cracking and / or peeling observed.

[0119] [Table 1]

[0120] As is clear from Table 1, the polarizing plates with phase difference layers in the examples exhibit suppressed cracking and delamination even under harsh high-temperature and high-humidity environments. In each example and comparative example, the HAST test was performed without the liquid crystal alignment solidification layer, but the results were the same as above regardless of the presence or absence of the liquid crystal alignment solidification layer. [Industrial applicability]

[0121] The polarizing plate with a phase difference layer of the present invention can be suitably used in image display devices (typically liquid crystal display devices and organic EL display devices). [Explanation of Symbols]

[0122] 10 Polarizing plates 11 Polarizer 12 Protective layer 21 First retardation layer 22 Second retardation layer 31. The First Layer 32. The Second Layer 100 Polarizing plate with retardation layer

Claims

1. A first phase difference layer having a first principal surface and a second principal surface facing each other, A polarizer disposed on the first main surface side of the first phase difference layer, The first phase difference layer comprises a first layer disposed on the second main surface side, and / or the second layer disposed on the first main surface side, The first layer and the second layer are arranged in direct contact with the first phase difference layer. The first phase difference layer is composed of a stretched resin film and satisfies the relationship Re(450) < Re(550), The first layer and the second layer have a shear fracture strength of 60 MPa or more. At least one of the first layer and the second layer has a shear fracture strength of 85 MPa or more. At least one of the first layer and the second layer is a hard coat layer. Polarizing plate with retardation layer: Here, Re(450) and Re(550) are the in-plane phase differences measured with light of wavelengths 450 nm and 550 nm at 23°C, respectively.

2. A first phase difference layer having a first principal surface and a second principal surface facing each other, A polarizer disposed on the first main surface side of the first phase difference layer, A first layer disposed on the second main surface side of the first phase difference layer, The first phase difference layer has a second layer disposed on the first main surface side, The first layer and the second layer are arranged in direct contact with the first phase difference layer. The first phase difference layer is composed of a stretched resin film and satisfies the relationship Re(450) < Re(550), The first and second layers have a shear fracture strength of 60 MPa or more. The first and second layers are hard coat layers. Polarizing plate with retardation layer: Here, Re(450) and Re(550) are the in-plane phase differences measured with light of wavelengths 450 nm and 550 nm at 23°C, respectively.

Images