Polarizing plate with a phase difference layer and image display device using the same

Abstract

To provide a polarization plate with a retardation layer having excellent durability even under a harsh high-temperature and high humidity environment.SOLUTION: A polarization plate with a retardation layer includes a polarization plate with a polarizer, a heat-resistant and moisture-resistant layer and a retardation layer, in this order. The retardation layer is composed of an oriented film of a resin film, and satisfies a relation of Re(450)<Re(550). The heat-resistant and moisture-resistant layer is a hardened layer or a solidified layer of a resin, and a storage modulus thereof is 100 MPa or more. Here, Re(450) and Re(550) are in-plane phase differences measured with light respectively at wavelength 450 nm and 550 nm at 23°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polarizing plate with a retardation layer and an image display device using the polarizing plate with a retardation layer.

Background Art

[0002] In recent years, image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices, inorganic EL display devices) have been rapidly spreading. Typically, a polarizing plate and a retardation plate are used in image display devices. Practically, a polarizing plate with a retardation layer in which a polarizing plate and a retardation plate are integrated is widely used (for example, Patent Document 1). In recent years, with the expansion of the applications of image display devices, various performance improvements have been demanded for the polarizing plate with a retardation layer. For example, in some cases, the durability of the polarizing plate with a retardation layer in a severe high-temperature and high-humidity environment, which has not been required conventionally, is demanded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer having excellent durability even in a severe high-temperature and high-humidity environment.

Means for Solving the Problems

[0005] The retardation film - attached polarizing plate according to an embodiment of the present invention has, in this order, a polarizing plate including a polarizer, a heat - and moisture - resistant layer, and a retardation film. The retardation film is composed of a stretched film of a resin film and satisfies the relationship Re(450)<Re(550). The heat - and moisture - resistant layer is a cured layer or a solidified layer of a resin, and its storage elastic modulus is 100 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 retardation film is 100 nm to 200 nm, and the angle formed by the slow axis of the 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 further has another retardation film on the side opposite to the polarizing plate of the retardation film, which shows the relationship of nz>nx = ny in refractive index characteristics, and another heat - and moisture - resistant layer is provided between the retardation film and the other retardation film. The other heat - and moisture - resistant layer is a cured layer or a solidified layer of a resin, and its storage elastic modulus is 100 MPa or more. In one embodiment, the other heat - and moisture - resistant layer also functions as an adhesive layer. In another embodiment, an adhesive layer is provided between the other heat - and moisture - resistant layer and the other retardation film. In one embodiment, the retardation film contains at least one bonding group selected from the group consisting of a carbonate bond and an ester bond, and at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and contains a resin having positive refractive index anisotropy:

Chemical formula

Chemical formula

Advantages of the Invention

[0006] According to the embodiment of the present invention, a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature and high-humidity environment can be realized.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Modes for Carrying Out the Invention

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

[0009] (Definitions of Terms and Symbols) The definitions of terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) “nx” is the refractive index in the direction where 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 Phase Difference (Re) “Re(λ)” is the in-plane phase difference of the film measured with light of wavelength λ nm at 23°C. For example, “Re(450)” is the in-plane phase difference of the film measured with light of wavelength 450 nm at 23°C. Re(λ) is obtained by the formula: Re = (nx - ny) × d, where d (nm) is the thickness of the film. (3) Phase Difference in the Thickness Direction (Rth) “Rth(λ)” is the phase difference in the thickness direction of the film measured with light of wavelength λ nm at 23°C. For example, “Rth(450)” is the phase difference in the thickness direction of the film measured with light of wavelength 450 nm at 23°C. Rth(λ) is obtained by the formula: Rth = (nx - nz) × d, where d (nm) is the thickness of the film. (4) Nz Coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, unless otherwise specified, the angle includes angles in both the clockwise and counterclockwise directions.

[0010] A. Overall Configuration of Polarizing Plate with Phase Difference Layer FIG. 1 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to one embodiment of the present invention. The polarizing plate 100 with a retardation layer in the illustrated example has a polarizing plate 10, a heat and moisture resistant layer 31, and a retardation layer 21 in this order. That is, in the embodiment of the present invention, the heat and moisture resistant layer 31 is provided between the polarizing plate 10 and the retardation layer 21. The polarizing plate 10 includes a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11, and a second protective layer 13 disposed on the other side of the polarizer 11. Depending on the purpose, one of the first protective layer 12 and the second protective layer 13 may be omitted. For example, since the retardation layer 21 can also function as a protective layer of the polarizer 11, the second protective layer 13 may be omitted.

[0011] The retardation layer 21 is composed of a stretched film of a resin film and satisfies the relationship of Re(450) < Re(550). The Re(550) of the retardation layer 30 is typically 100 nm to 200 nm. The angle formed by the slow axis of the 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°; alternatively, preferably 130° to 140°, more preferably 132° to 138°, still more preferably 134° to 136°, and particularly preferably about 135°.

[0012] The heat-resistant and moisture-resistant layer 31 is a cured layer or solidified layer of resin, and its storage elastic modulus is 100 MPa or more. According to an embodiment of the present invention, by providing such a heat-resistant and moisture-resistant layer between the polarizing plate and the retardation layer, a polarizing plate with a retardation layer having excellent durability even in a harsh high-temperature and high-humidity environment can be realized. Specifically, a polarizing plate with a retardation layer in which cracks and peeling are suppressed even in a harsh high-temperature and high-humidity environment can be realized. The details are as follows. The retardation layer used in the embodiment of the present invention exhibits very excellent circular polarization characteristics, so that a polarizing plate with a retardation layer (circular polarizing plate) having a very excellent antireflection function can be realized. Furthermore, by using such a retardation layer in combination with another retardation layer having a refractive index characteristic of nz > nx = ny, which will be described later, the antireflection function can be widened in the viewing angle. On the other hand, the stretched film of the resin film constituting such a retardation layer has a large heat shrinkage and a high water absorption rate, so that the reliability in a high-temperature and high-humidity environment may be insufficient. Furthermore, cracks and / or peeling may occur in a harsh high-temperature and high-humidity environment, which is becoming a new standard for characteristics in recent years. According to an embodiment of the present invention, by providing the above-described heat-resistant and moisture-resistant layer between the polarizing plate and the retardation layer, while maintaining the excellent characteristics of the retardation layer, the durability and reliability of the entire polarizing plate with a retardation layer in a harsh high-temperature and high-humidity environment can be significantly improved. As a result, a polarizing plate with a retardation layer in which cracks and peeling are suppressed even in a harsh high-temperature and high-humidity environment can be realized. Note that the above mechanism is an estimation, and the mechanism does not limit or restrict the embodiments of the present invention.

[0013] FIG. 2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention. The polarizing plate 101 with a retardation layer in the illustrated example further has another retardation layer 22 on the side opposite to the polarizing plate 10 of the retardation layer 21, and the refractive index characteristics show a relationship of nz>nx = ny. Another retardation layer 22 typically shows a relationship of nz>nx = ny in refractive index characteristics. By providing such another retardation layer, reflection in an oblique direction can be prevented well, and a wide viewing angle of the antireflection function can be achieved. In the present embodiment, another heat and moisture resistant layer 32 is further provided between the retardation layer 21 and another retardation layer 22. Another heat and moisture resistant layer 32 can function as an adhesive layer for fixing the retardation layer 21 and another retardation layer 22. When another heat and moisture resistant layer 32 does not function as an adhesive layer, an adhesive layer (not shown) can be provided between another heat and moisture resistant layer 32 and another retardation layer 22. Hereinafter, the retardation layer 21 may be referred to as the first retardation layer, and another retardation layer 22 may be referred to as the second retardation layer; the heat and moisture resistant layer 31 may be referred to as the first heat and moisture resistant layer, and another heat and moisture resistant layer 32 may be referred to as the second heat and moisture resistant layer.

[0014] The polarizing plate with a retardation layer may further have an additional retardation layer (not shown). The optical characteristics (e.g., refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, etc. of the additional retardation layer can be appropriately set according to the purpose.

[0015] The polarizing plate with a retardation layer may be in a sheet form or in a long strip form. In this specification, "long strip form" means an elongated shape where the length is sufficiently long with respect to the width, for example, including an elongated shape where the length is 10 times or more, preferably 20 times or more, the width. The long strip-shaped polarizing plate with a retardation layer can be wound into a roll.

[0016] Practically, the polarizing plate with a retardation layer has an adhesive layer (not shown) as the outermost layer on the side opposite to the polarizing plate of the retardation layer. Due to the adhesive layer, the polarizing plate with a retardation layer can be attached to the image display cell. Further, it is preferable that a release film is temporarily attached to the surface of the adhesive layer until the polarizing plate with a retardation layer is put into use. By temporarily attaching the release film, the adhesive layer is protected and the roll formation of the polarizing plate with a retardation layer becomes possible.

[0017] Hereinafter, the components of the polarizing plate with a retardation layer will be described.

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

[0019] Specific examples of the polarizer composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films, which are subjected to dyeing treatment with dichroic substances such as iodine and dichroic dyes and stretching treatment, and polyene-based oriented films such as dehydrated products of PVA and dehydrochlorinated products of polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching it is used because of its excellent optical properties.

[0020] The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment, during the dyeing, or after the stretching and then the dyeing. If necessary, the PVA-based film is subjected to swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. For example, by immersing the PVA-based film in water and washing it before dyeing, not only can the dirt and blocking inhibitor on the surface of the PVA-based film be washed, but also the PVA-based film can be swollen to prevent uneven dyeing.

[0021] Specific examples of the polarizer obtained using the above laminate of two or more layers include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate. The polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by coating on the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate and drying it to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In the present embodiment, preferably, a PVA-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. Further, stretching may further include, if necessary, air stretching the laminate at a high temperature (for example, 95 °C or higher) before stretching in the aqueous boric acid solution. In addition, in the present embodiment, preferably, the laminate is subjected to a drying shrinkage treatment in which it is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of the present embodiment includes subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, a water stretching treatment, and a drying shrinkage treatment in this order. By introducing the auxiliary stretching, even when PVA is applied on a thermoplastic resin, it is possible to increase the crystallinity of PVA and achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, problems such as a decrease in the orientation of PVA or dissolution when immersed in water in the subsequent dyeing process and stretching process can be prevented, and high optical properties can be achieved. Further, when the PVA-based resin layer is immersed in a liquid, compared with the case where the PVA-based resin layer does not contain a halide, the disorder of the orientation of polyvinyl alcohol molecules and the decrease in the orientation can be suppressed. As a result, the optical properties of the polarizer obtained through treatment steps such as a dyeing treatment and a water stretching treatment, in which the laminate is immersed in a liquid, can be improved. Furthermore, by shrinking the laminate in the width direction by the drying shrinkage treatment, the optical properties can be improved.The obtained resin substrate / polarizer laminate may be used as it is (i.e., the resin substrate may be used as the protective layer of the polarizer), and an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface obtained by peeling the resin substrate from the resin substrate / polarizer laminate, or on the surface opposite to the peeled surface. Details of such a method for producing a polarizer are described, for example, in JP-A-2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are incorporated herein by reference.

[0022] The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, still more preferably 10 μm or less, particularly preferably 8 μm or less, and especially preferably 5 μm or less. The lower limit of the thickness of the polarizer can be, for example, 1 μm. If the thickness of the polarizer is within such a range, curling during heating can be favorably suppressed, and good appearance durability during heating can be obtained.

[0023] The polarizer preferably exhibits absorption dichroism at any wavelength in the range of 380 nm to 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

[0024] C. Protective Layer The first protective layer 12 and the second protective layer 13 are each formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of the material that is the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, cyclic olefin-based (e.g., polynorbornene-based), polyolefin-based, (meth)acrylic-based, acetate-based, and other transparent resins. Also included are thermosetting resins or ultraviolet curable resins such as (meth)acrylic-based, urethane-based, (meth)acrylic urethane-based, epoxy-based, and silicone-based resins. In addition, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the above resin composition.

[0025] The first 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 environment of 85°C for 240 hours. The smaller the shrinkage rate, the more preferable it is, and the lower limit can be, for example, 0.01%. If the shrinkage rate is within such a range, cracks in the polarizer and peeling between the polarizer and the retardation layer in a harsh high-temperature and high-humidity environment can be suppressed more favorably. The first protective layer 12 is preferably composed of a triacetyl cellulose (TAC) film or a cyclic olefin-based resin film. The TAC film and the cyclic olefin-based resin film are formed into a film by extrusion or casting and do not include stretching during film formation. As a result, since the residual stress is small, the above-described desired shrinkage rate can be achieved.

[0026] The retardation film - attached polarizing plate is typically disposed on the viewing side of an image display device as described later, and the first protective layer 12 is typically disposed on the viewing side thereof. Therefore, the first protective layer 12 may be subjected to surface treatments such as hard coat treatment, antireflection treatment, anti - sticking treatment, antiglare treatment, etc., as required. Further / or, the first protective layer 12 may be subjected to a treatment (typically, imparting an (elliptical) polarization function, imparting an extremely high retardation) for improving visibility when viewing through polarized sunglasses, as required. By performing such a treatment, excellent visibility can be realized even when viewing a display screen through a polarizing lens such as polarized sunglasses. Therefore, the retardation film - attached polarizing plate can be suitably applied to an image display device that can be used outdoors.

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

[0028] In one embodiment, the second protective layer 13 is preferably optically isotropic. As used herein, "optically isotropic" means that the in - plane retardation Re(550) is 0 nm to 10 nm and the retardation in the thickness direction Rth(550) is - 10 nm to + 10 nm. As described above, the second protective layer 13 may be omitted.

[0029] D. The first retardation layer D - 1. Characteristics of the first retardation layer The in - plane retardation Re(550) of the first retardation layer 21 is 100 nm to 200 nm as described above, preferably 110 nm to 180 nm, more preferably 120 nm to 160 nm, and even more preferably 130 nm to 150 nm. That is, the first retardation layer can function as a so - called λ / 4 plate.

[0030] The first retardation layer satisfies the relation Re(450) < Re(550) as described above, and preferably further satisfies the relation Re(550) < Re(650). That is, the first retardation layer exhibits an inverse-dispersion wavelength dependence in which the retardation value increases with 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 even more preferably 0.8 to 0.9. Re(650) / Re(550) is preferably 1.0 or more and less than 1.15, more preferably 1.03 to 1.1.

[0031] Since the first retardation layer has an in-plane retardation as described above, it has a relation of nx > ny. As long as the first retardation layer has a relation of nx > ny, it exhibits any appropriate refractive index characteristics. The refractive index characteristics of the first retardation layer typically exhibit a relation 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 even more preferably 0.9 to 1.2. By satisfying such a relation, when a polarizing plate with a retardation layer is used in an image display device, a very excellent reflected hue can be achieved.

[0032] The thickness of the first retardation layer can be set so as to function most appropriately as a quarter-wave 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.

[0033] 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.

[0034] 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 due to a synergistic effect with the effect of the above shrinkage rate. In this specification, "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).

[0035] 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 a polarizing plate with a retardation layer is applied to an image display device.

[0036] D-2. Constituent Materials of the First Retardation Layer The first retardation layer typically contains a resin including at least one bonding group selected from the group consisting of carbonate bonds and ester bonds. In other words, the first retardation layer contains a polycarbonate resin, a polyester resin, or a polyester carbonate resin (hereinafter, these may be collectively simply referred to as a polycarbonate resin).

[0037] In one embodiment, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanols, di-, tri- or polyethylene glycols, and alkylene glycols or spiroglycols. Preferably, the polycarbonate resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from an alicyclic dimethanol and / or a structural unit derived from di-, tri- or polyethylene glycol; more preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di-, tri- or polyethylene glycol. The polycarbonate resin may optionally include structural units derived from other dihydroxy compounds. Details of the polycarbonate resin that can be preferably used in the present invention are described, for example, in JP-A Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, and 2015-212818, and the description is incorporated herein by reference.

[0038] In one embodiment, the polycarbonate resin contains at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2). These structural units are structural units derived from divalent oligofluorene, and may hereinafter be referred to as oligofluorene structural units. Such a polycarbonate resin has positive refractive index anisotropy.

[0039] In one embodiment, the first retardation layer may further contain an acrylic resin. The content of the acrylic resin is typically 0.5% by mass to 1.5% by mass. In the present specification, the percentage or part in the unit of "mass" is synonymous with the percentage or part in the unit of "weight".

[0040] In one embodiment, the first retardation 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 "Irganox1010" (manufactured by BASF), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene: trade name "Irganox1330" (manufactured by BASF), tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate: trade name "Irganox3114" (manufactured by BASF), stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate: trade name "Irganox1076" (manufactured by BASF), 2,2'-thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]: trade name "Irganox1035" (manufactured by BASF), N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]: trade name "Irganox1098" (manufactured by BASF), bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)]: trade name "Irganox245" (manufactured by BASF), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] trade name "Irganox259" (manufactured by BASF), 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol: trade name "Irganox565" (manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol: trade name "Adekastab LA-31" (manufactured by ADEKA), etc. The content of the antioxidant is typically 1.5% by mass to 3.5% by mass.

[0041] 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 are each independently a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and R 4 ~R 9 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group. However, R 4 ~R 9 may be the same as or different from each other, and at least two adjacent groups among R 4 ~R 9 may be bonded to each other to form a ring.

[0042] The content of the oligofluorene structural unit in the polycarbonate resin is preferably 1% by mass to 40% by mass, more preferably 10% by mass to 35% by mass, still more preferably 15% by mass to 30% by mass, and particularly preferably 18% by mass to 25% by mass with respect to the entire resin. If the content of the oligofluorene structural unit is too high, there may be problems such as the photoelastic coefficient becoming too large, the reliability becoming insufficient, and the retardation development property becoming insufficient. Furthermore, since the proportion of the oligofluorene structural unit in the resin increases, the range of molecular design becomes narrow, and it may be difficult to improve when resin modification is required. On the other hand, even if the desired inverse dispersion wavelength dependence is obtained with a very small amount of the oligofluorene structural unit, in this case, since the optical properties change sensitively according to a slight variation in the content of the oligofluorene structural unit, it may be difficult to manufacture so that various properties fall within a certain range.

[0043] Details of the oligofluorene structural unit are described, for example, in the pamphlet of International Publication No. 2015 / 159928. This publication is incorporated herein by reference.

[0044] <Other structural units> The polycarbonate resin may typically contain other structural units in addition to the oligofluorene structural unit. In one embodiment, the other structural units may preferably be derived from a dihydroxy compound or a diester compound. In order to exhibit the desired inverse dispersion wavelength property, it is necessary to incorporate a structural unit having a positive intrinsic birefringence into the polymer structure together with the oligofluorene structural unit having a negative intrinsic birefringence. Therefore, as another monomer to be copolymerized, a dihydroxy compound or a diester compound that is a raw material for a structural unit having a positive birefringence is more preferable.

[0045] Examples of the copolymerization monomer include a compound capable of introducing a structural unit containing an aromatic ring and a compound not introducing a structural unit containing an aromatic ring, that is, a compound composed of an aliphatic structure.

[0046] Specific examples of the compound composed of the aliphatic structure are listed below. Dihydroxy compounds of linear 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, 1,12-dodecanediol, etc.; Dihydroxy compounds of branched aliphatic hydrocarbons such as neopentyl glycol, hexylene glycol, etc.; Secondary alcohols and tertiary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, etc., which are dihydroxy compounds; Dihydroxy compounds that are primary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, 2,6-decalindimethanol, 1,5-decalindimethanol, 2,3-decalindimethanol, 2,3-norbornanedimethanol, 2,5-norbornanedimethanol, 1,3-adamantanedimethanol, limonene, etc., which are dihydroxy compounds derived from terpene compounds; Oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, etc.; Dihydroxy compounds having a cyclic ether structure such as isosorbide; Dihydroxy compounds having a cyclic acetal structure such as spiroglycol, dioxanglycol, etc.; Alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc.; Aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.

[0047] Specific examples of the compound capable of introducing the structural unit containing the aromatic ring 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(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, 4,4'-dihydroxydiphenylether, 4,4'-dihydroxy-3,3'-dichlorodiphenylether and other aromatic bisphenol compounds; 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, bis(4-(2-hydroxyethoxy)phenyl)sulfone and other dihydroxy compounds having an ether group bonded to an aromatic group;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, 2,6-naphthalenedicarboxylic acid, etc.;

[0048] In addition, the aliphatic dicarboxylic acid and aromatic dicarboxylic acid components listed above can be used as raw materials for the polyester carbonate as the dicarboxylic acid itself. However, depending on the production method, dicarboxylic acid esters such as methyl ester form and phenyl ester form, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

[0049] As the copolymer monomer, dihydroxy compounds having a fluorene ring such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, etc., which are conventionally known as compounds having a structural unit with negative birefringence, and dicarboxylic acid compounds having a fluorene ring can also be used in combination with oligofluorene compounds.

[0050] Among the structural units that can be introduced by the compound having the alicyclic structure, the resin used in the embodiment of the present invention preferably contains a structural unit represented by the following formula (3) as a copolymer component.

Chemical formula

[0051] Spiroglycol can be used as the dihydroxy compound for introducing the structural unit of the formula (3).

[0052] In the resin used in the embodiment of the present invention, the structural unit represented by the 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, still more preferably 20% by mass or more, and particularly preferably 25% by mass or more. If the content of the structural unit represented by the formula (3) is at least the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. Furthermore, the compatibility with the acrylic resin is improved, and the transparency of the resulting resin composition can be further improved. In addition, since spiroglycol has a relatively slow polymerization reaction rate, controlling the content to be at most the upper limit makes it easier to control the polymerization reaction.

[0053] The resin used in the present invention preferably further contains a structural unit represented by the following formula (4) as a copolymerization component.

Chemical formula

[0054] Examples of the dihydroxy compound capable of introducing the structural unit represented by the formula (4) include isosorbide (ISB), isomannide, and isoidide, which are in a stereoisomeric relationship. These may be used alone or in combination of two or more.

[0055] In the resin used in the embodiment of the present invention, the structural unit represented by the formula (4) is preferably contained in an amount of 5% by mass or more and 90% by mass or less. The upper limit is more preferably 70% by mass or less, and particularly preferably 50% by mass or less. The lower limit is more preferably 10% by mass or more, and particularly preferably 15% by mass or more. If the content of the structural unit represented by the formula (4) is at least the lower limit, sufficient mechanical properties, heat resistance, and a low photoelastic coefficient can be obtained. In addition, since the structural unit represented by the formula (4) has a characteristic of high water absorption, if the content of the structural unit represented by the formula (4) is at most the upper limit, the dimensional change of the molded body due to water absorption can be suppressed within an allowable range.

[0056] The resin used in the embodiments of the present invention may further contain another structural unit. Such a structural unit may be referred to as "other structural unit". As monomers having other structural units, it is more preferable to employ 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, 1,4-cyclohexanedicarboxylic acid (and its derivatives), and 1,4-cyclohexanedimethanol and tricyclodecanedimethanol are particularly preferable. Resins containing structural units derived from these monomers are excellent in the balance of optical properties, heat resistance, mechanical properties, etc. Further, since the polymerization reactivity of the diester compound is relatively low, from the viewpoint of enhancing the reaction efficiency, it is preferable not to use diester compounds other than the diester compound containing an oligo fluorene structural unit.

[0057] 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, still 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. When the glass transition temperature is outside the above range, the heat resistance tends to deteriorate, and dimensional changes may occur after film formation, or the quality reliability under the use conditions of the first retardation layer may deteriorate. On the other hand, when the glass transition temperature is excessively high, film thickness unevenness may occur during film formation, the film may become brittle, the stretchability may deteriorate, and the transparency of the film may be impaired.

[0058] D-2-2. Acrylic resin As the acrylic resin, an acrylic resin as a thermoplastic resin is used. Examples of the monomer that becomes the structural unit of the acrylic resin include the following compounds: methyl methacrylate, methacrylic acid, methyl acrylate, acrylic acid, benzyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, glycidyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, acrylic (meth)acrylate, 2-hydroxyethyl (meth)acrylate, succinic acid 2-(meth)acryloyloxyethyl, maleic acid 2-(meth)acryloyloxyethyl, phthalic acid 2-(meth)acryloyloxyethyl, hexahydrophthalic acid 2-(meth)acryloyloxyethyl, 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 alone or in combination of two or more. The form of using a combination of two or more monomers includes copolymerization of two or more monomers, blending of two or more homopolymers of one monomer, and combinations thereof. Further, other monomers copolymerizable with these acrylic monomers (for example, olefin monomers, vinyl monomers) may be used in combination.

[0059] The acrylic resin contains a structural unit derived from methyl methacrylate. The content of the structural unit 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, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. When it is within this range, excellent compatibility with the polycarbonate resin of the present invention can be obtained. As structural units other than methyl methacrylate, methyl acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, and styrene are preferably used. By copolymerizing methyl acrylate, the thermal stability can be improved. By using phenyl (meth) acrylate, benzyl (meth) acrylate, or styrene, the refractive index of the acrylic resin can be adjusted, and thus the transparency of the resulting resin composition can be improved by adjusting to match the refractive index of the resin to be combined. By using such an acrylic resin, a reverse dispersion retardation film excellent in stretchability and retardation expression property and having a small haze can be obtained.

[0060] The weight average molecular weight Mw of the acrylic resin is 10,000 or more and 200,000 or less. The lower limit is preferably 30,000 or more, and particularly preferably 50,000 or more. The upper limit is preferably 180,000 or less, and particularly preferably 150,000 or less. If the molecular weight is within such a range, compatibility with the polycarbonate resin can be obtained, thereby improving the transparency of the final retardation film (retardation layer) and obtaining an effect of sufficiently improving the stretchability during stretching. The above-mentioned weight average molecular weight is the molecular weight in terms of polystyrene measured by GPC. Further, from the viewpoint of compatibility, it is preferable that the acrylic resin does not substantially contain a branched structure. The absence of a branched structure can be confirmed by, for example, the GPC curve of the acrylic resin being unimodal.

[0061] D-2-3. Blend of polycarbonate resin and acrylic resin When a polycarbonate resin and an acrylic resin are used in combination, the polycarbonate resin and the acrylic resin are blended and used in a method for producing a retardation film (first retardation layer) as a resin composition (the production method will be described later in Section C-3). The polycarbonate resin and the acrylic resin can preferably be blended in a molten state. As a method for blending in a molten state, typically, melt kneading using an extruder can be mentioned. 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 such a range, pellets of a resin composition in which both resins are uniformly blended can be obtained while suppressing thermal decomposition. When the molten resin temperature in the extruder exceeds 280°C, coloring and / or thermal decomposition of the resin may occur. On the other hand, when the molten resin temperature in the extruder is below 200°C, the resin viscosity may become too high, imposing an excessive load on the extruder, or the melting of the resin may be insufficient. In addition, as the configuration of the extruder, the configuration of the screw, etc., any appropriate configuration can be adopted. In order to obtain the transparency of the resin that can withstand optical film applications, it is preferable to use a twin-screw extruder. Furthermore, since residual low-molecular components in the resin and low-molecular-weight thermal decomposition components during extrusion kneading may contaminate the cooling roll and the conveying roll in the film forming process and the stretching process, it is preferable to use an extruder equipped with a vacuum vent to remove these components.

[0062] In the resin composition (resulting in the first retardation layer), the content of the acrylic resin is 0.5% by mass or more and 2.0% by mass or less as described above. The lower limit is more preferably 0.6% by mass or more. The upper limit is preferably 1.5% by mass or less, more preferably 1.0% by weight or less, still more preferably 0.9% by weight or less, and particularly preferably 0.8% by mass or less. Thus, by blending the acrylic resin with the polycarbonate resin in a very limited ratio, the extensibility and the retardation-developing property can be significantly increased. Furthermore, haze can be suppressed. Such an effect is not theoretically obvious and is an excellent unexpected effect obtained through trial and error. Note that if the content of the acrylic resin is too small, the above effects may not be obtained. On the other hand, if the content of the acrylic resin is too large, the haze may increase. Also, the extensibility and the retardation-developing property are often insufficient or rather decreased compared to the case within the above range.

[0063] For the purpose of modifying properties such as mechanical properties and / or solvent resistance, the resin composition may be further blended with synthetic resins such as aromatic polycarbonate, aliphatic polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, acrylic, amorphous polyolefin, ABS, AS, polylactic acid, polybutylene succinate, rubber, and combinations thereof.

[0064] The resin composition may further contain additives. Specific examples of the additives include heat stabilizers, antioxidants, catalyst deactivators, ultraviolet absorbers, light stabilizers, release agents, dyes and pigments, impact modifiers, antistatic agents, lubricants, plasticizers, compatibilizers, nucleating agents, flame retardants, inorganic fillers, and foaming agents. The type, number, combination, content, etc. of the additives contained in the resin composition can be appropriately set according to the purpose.

[0065] D-3. Method for Forming the First Retardation Layer The first retardation layer is obtained by forming a film from the polycarbonate resin described in C-2 above (or the resin composition when an acrylic resin is used in combination), and further stretching the film. As the method for forming the film, any appropriate molding process can be employed. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, cast coating (e.g., casting), calender molding, hot pressing, etc. Among them, the extrusion molding method or the cast coating method, which can enhance the smoothness of the obtained film and obtain good optical uniformity, is preferred. Since there is a risk of problems caused by residual solvents in the cast coating method, the extrusion molding method is particularly preferred, and among them, the melt extrusion molding method using a T-die is preferred from the viewpoints of film productivity and ease of subsequent stretching treatment. The molding conditions can be appropriately set according to the composition and type of the resin used, the properties desired for the first retardation layer, etc. In this way, a resin film containing a polycarbonate resin and, if necessary, an acrylic resin can be obtained.

[0066] The thickness of the resin film (unstretched film) can be set to any appropriate value according to the desired thickness of the obtained first retardation layer, the desired optical properties, the stretching conditions described below, etc. Preferably, it is 50 μm to 300 μm.

[0067] For the above stretching, any appropriate stretching method and stretching conditions (e.g., stretching temperature, stretching ratio, stretching direction) can be employed. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinkage, and fixed-end shrinkage can be used alone, simultaneously, or sequentially. Regarding the stretching direction, it can be performed in various directions and dimensions such as the length direction, width direction, thickness direction, and diagonal direction.

[0068] By appropriately selecting the above stretching method and stretching conditions, a retardation layer having the above desired optical properties (e.g., refractive index property, in-plane retardation, Nz coefficient) can be obtained.

[0069] In one embodiment, the stretching temperature of the above film is preferably the glass transition temperature (Tg) of the polycarbonate resin to Tg + 30°C, more preferably Tg to Tg + 15°C, and most preferably Tg to Tg + 10°C. When an acrylic resin is used in combination, the stretching temperature is a temperature below Tg. Usually, when stretching a polycarbonate resin film, stretching is substantially impossible at a temperature below Tg because the film is in a glassy state. On the other hand, by blending a small amount of an acrylic resin (typically, polymethyl methacrylate), stretching below Tg becomes possible without substantially changing the Tg of the polycarbonate resin. Furthermore, although not clearly theoretical, by stretching below Tg, a reverse dispersion retardation film (the first retardation layer) excellent in stretchability and retardation expression and having a low haze can be realized. 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. Note that the above film can be appropriately stretched even at a temperature higher than Tg as long as it is, for example, about Tg + 5°C or, for example, up to about Tg + 2°C.

[0070] The stretched film obtained as described above is, if necessary, subjected to a heat treatment of heating at a temperature of 105°C or higher for 2 minutes or longer. By performing the heat treatment, the first retardation layer having the above 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.

[0071] If necessary, the stretched film may be subjected to a relaxation treatment. Thereby, the stress generated by stretching can be relaxed, and a retardation layer having the above-described desired shrinkage rate can be formed. As the relaxation treatment conditions, any appropriate conditions can be adopted. For example, the stretched film is shrunk at a predetermined relaxation temperature and a predetermined relaxation rate (shrinkage rate) along the stretching direction. The relaxation temperature is preferably 60°C to 150°C. The relaxation rate is preferably 3% to 6%. When the relaxation treatment is performed, the relaxation treatment can typically be performed before the above heat treatment.

[0072] In the above manner, a retardation film constituting the first retardation layer can be obtained.

[0073] E. Second Retardation Layer As described above, the second retardation layer can be a so-called positive C-plate having a refractive index characteristic of nz > nx = ny. By using a positive C-plate as the second retardation layer, reflection in the oblique direction can be satisfactorily prevented, and the viewing angle of the antireflection function can be widened. In this case, the retardation Rth(550) in the thickness direction of the second retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, still more preferably -90 nm to -200 nm, and particularly preferably -100 nm to -180 nm. 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 retardation Re(550) of the second retardation layer can be less than 10 nm.

[0074] The second retardation layer having a refractive index characteristic of nz > nx = ny can be formed of any suitable material. The second retardation layer preferably consists of a film containing a liquid crystal material fixed in a homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compounds and the method for forming the retardation layer described in paragraphs

[0020] to

[0028] of JP-A-2002-333642. In this case, the thickness of the second retardation 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.

[0075] F. Heat and moisture resistant layer Hereinafter, the first heat and moisture resistant layer 31 and the second heat and moisture resistant layer 32 will be collectively described as the heat and moisture resistant layer. The first heat and moisture resistant layer 31 and the second heat and moisture resistant layer 32 may have the same configuration or different configurations.

[0076] Typically, as described above, the heat and moisture resistant layer is a cured layer or a solidified layer of a resin. The cured layer can 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 the cured layer include, in addition to a simple cured layer, a hard coat layer, an adhesive layer composed of an active energy ray-curable adhesive, and a crosslinked layer with a crosslinking agent. The solidified layer can be, for example, a solidified layer of a coating film of an organic solvent solution of a thermoplastic resin.

[0077] The storage elastic modulus of the heat- and moisture-resistant layer is 100 MPa or more as described above, preferably 200 MPa or more, more preferably 500 MPa or more, still more preferably 800 MPa or more, particularly preferably 1200 MPa or more, even more particularly preferably 1800 MPa or more, and most preferably 2000 MPa or more. The upper limit of the storage elastic modulus can be, for example, 4000 MPa. If the storage elastic modulus is in such a range, a polarizing plate with a retardation layer having excellent durability can be realized even in a harsh high-temperature and high-humidity environment. For example, even in a HAST test (JIS C60068), which is an acceleration test regarding durability in a high-temperature and high-humidity environment, a polarizing plate with a retardation layer in which neither cracks nor peeling occur can be realized.

[0078] The heat- and moisture-resistant layer preferably has substantially optical isotropy. The in-plane retardation Re(550) of the heat- and moisture-resistant layer is preferably from 0 nm to 10 nm, more preferably from 0 nm to 5 nm, still more preferably from 0 nm to 3 nm, and particularly preferably from 0 nm to 2 nm. The retardation Rth(550) in the thickness direction of the heat- and moisture-resistant layer is preferably from -10 nm to +10 nm, more preferably from -5 nm to +5 nm, still more preferably from -3 nm to +3 nm, and particularly preferably from -2 nm to +2 nm. If the Re(550) and Rth(550) of the heat- and moisture-resistant layer are in such ranges, when a polarizing plate with an adhesive layer including the heat- and moisture-resistant layer is applied to an image display device, an adverse effect on display characteristics can be prevented.

[0079] The light transmittance at 380 nm at a thickness of 3 μm of the heat- and moisture-resistant layer is preferably as high as possible. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more. If the light transmittance is in such a range, desired transparency can be ensured. The light transmittance can be measured, for example, by a method according to ASTM-D-1003.

[0080] The lower the haze of the heat- and moisture-resistant layer, the more preferable it is. Specifically, the haze is preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, and particularly preferably 1% or less. When the haze is 5% or less, a good clear feeling can be given to the retardation film-attached polarizing plate. As a result, the display content of the image display device can be visually recognized well.

[0081] The higher the adhesion between the heat- and moisture-resistant layer and the first retardation layer, the more preferable it is. Specifically, the adhesion preferably shows a state of 2 or less, more preferably 1 or less, and particularly preferably 0 in the cross-cut peeling test described in JIS K 5600-5-6. When the adhesion is 2 or less in the cross-cut peeling test, peeling of the retardation film-attached polarizing plate in a harsh high-temperature and high-humidity environment can be suppressed well, and problems related to the appearance such as peeling during rework can be suppressed.

[0082] The heat- and moisture-resistant layer is a cured layer or solidified layer of a resin, and any appropriate configuration can be adopted as long as it has the storage elastic modulus as described above. Hereinafter, representative examples will be described.

[0083] (Hard coat layer) The hard coat layer (substantially, the composition for forming the hard coat layer) contains a curing component and typically a photoinitiator. Representative examples of the curing component include active energy ray-curable (meth)acrylates. Examples of the active energy ray-curable (meth)acrylates include ultraviolet ray-curable (meth)acrylates and electron beam-curable (meth)acrylates. Preferably, it is an ultraviolet ray-curable (meth)acrylate. This is because the hard coat layer can be efficiently formed by simple processing operations. The ultraviolet ray-curable (meth)acrylate includes ultraviolet ray-curable monomers, oligomers, polymers, etc. The ultraviolet ray-curable (meth)acrylate preferably contains a monomer component and an oligomer component having two or more, more preferably 3 to 6 ultraviolet polymerization functional groups. Specific examples of the ultraviolet ray-curable (meth)acrylate include urethane acrylate, pentaerythritol triacrylate, ethoxylated glycerin triacrylate, and polyether urethane diacrylate. In addition to these, the curing component of the active energy ray-curable adhesive described later may be used. The curing component may be used alone or in combination of two or more. The curing method may be a radical polymerization method or a cationic polymerization method. In one embodiment, an organic-inorganic hybrid material in which silica particles, polysilsesquioxane compounds, etc. are blended with (meth)acrylate may be used. The constituent materials and formation methods of the hard coat layer are described in, for example, JP-A-2011-237789, JP-A-2020-064236, JP-A-2010-152331, etc. The descriptions of these publications are incorporated herein by reference. In this specification, "(meth)acryl" means acrylic and / or methacrylic. Also, (meth)acrylic may be simply referred to as acrylic.

[0084] (Active energy ray-curable adhesive) Examples of the active energy ray-curable adhesive include, for example, an ultraviolet ray-curable adhesive and an electron beam-curable adhesive. Further, from the viewpoint of the curing mechanism, examples of the active energy ray-curable adhesive include, for example, a radical-curable type, a cation-curable type, an anion-curable type, and a hybrid of a radical-curable type and a cation-curable type.

[0085] The adhesive contains a curing component, typically a photoinitiator, similar to the composition for forming the hard coat layer. Representative examples of the curing component include monomers and / or oligomers having functional groups such as (meth)acrylate groups and (meth)acrylamide groups. Specific examples of the curing component include tripropylene glycol diacrylate, 1,6 - hexanediol diacrylate, 1,9 - nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxy diethylene glycol acrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, EO - modified diglycerin tetraacrylate, γ - butyrolactone acrylate, polyethylene glycol diacrylate, hydroxy pivalic acid neopentyl glycol acrylate adduct, 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, dicyclopentadiene - type epoxy resin. As the curing component, 2 - (3,4 - epoxycyclohexyl)ethyltrimethoxysilane, 4 - hydroxybutyl acrylate, neopentyl glycol diacrylate, EO - modified triacrylate of isocyanuric acid, etc. may be used. In addition to these, the curing components of the above - mentioned hard coat layer may be used. The curing component may be used alone or in combination of two or more. The adhesive may further contain an oligomer component in addition to the above - mentioned curing component. By using the oligomer component, the viscosity of the adhesive before curing can be reduced and the workability can be improved. Representative examples of the oligomer component include (meth)acrylic oligomers and polyurethane - based (meth)acrylic oligomers.

[0086] (Cross - linked layer by cross - linking agent) The crosslinked layer (substantially, the composition forming the crosslinked layer) contains a curing component and a crosslinking agent. Examples of the curing component include those described above with respect to the hard coat layer and the active energy ray curable adhesive. The crosslinking agent may be a thermal crosslinking agent or a photo crosslinking agent. That is, the crosslinked layer may be a thermal crosslinked layer or a photo crosslinked layer. Examples of the thermal crosslinking agent include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, and imine-based crosslinking agents. The polyfunctional metal chelate is one in which a polyvalent metal is covalently bonded or coordinately bonded to an organic compound. Examples of the photo crosslinking agent include photoacid generators. Examples of the photoacid generator include organic peroxides. The thermal crosslinking agent or the photo crosslinking agent may be used alone or in combination of two or more thereof.

[0087] (Cured layer of thermosetting resin) As the thermosetting resin, any suitable thermosetting resin can be used as long as the cured layer has the above-described desired storage elastic modulus. Representative examples of the thermosetting resin include epoxy resins, (meth)acrylic resins, unsaturated polyester resins, polyurethane resins, alkyd resins, melamine resins, urea resins, and phenol resins. The thermosetting resin may be blended with, for example, an oxetane compound (monomer, oligomer, polymer).

[0088] (Solidified layer) As described above, the solidified layer can be, for example, a solidified layer of a coating film of an organic solvent solution of a thermoplastic resin. As the thermoplasticity, any suitable thermoplastic resin can be used as long as the solidified layer has the above-described desired storage elastic modulus. Representative examples of the thermoplastic resin include (meth)acrylic resins and epoxy resins.

[0089] (Meta)acrylic resins preferably have a glass transition temperature (Tg) of 100°C to 220°C, more preferably 110°C to 200°C, and even more preferably 120°C to 160°C. The (meta)acrylic resin may have a repeating unit containing a ring structure. Examples of the repeating unit containing a ring structure include a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. Only one type of the repeating unit containing a ring structure may be included in the repeating unit of the (meta)acrylic resin, or two or more types may be included. The (meta)acrylic resin may be a copolymer of a (meta)acrylic monomer and a boron-containing monomer (boron-containing (meta)acrylic resin). The boron-containing (meta)acrylic resin may have a repeating unit containing a ring structure as described above.

[0090] As the epoxy resin, an epoxy resin having an aromatic ring is preferably used. By using an epoxy resin having an aromatic ring, the adhesion between the solidified layer and the first retardation layer can be improved. Examples of the epoxy resin 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; novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolak 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.

[0091] As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the thermoplastic resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.

[0092] The resin concentration of the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film adhered to the first retardation layer can be formed.

[0093] The thickness of the heat 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 very thin thickness, the heat and moisture resistant layer can realize a polarizing plate with a retardation layer having excellent durability even in a harsh high temperature and high humidity environment. If the thickness of the heat and moisture resistant layer is too thin, it may be difficult to form the heat and moisture resistant layer itself, or even if it is formed, the effect may be insufficient. If the thickness of the heat and moisture resistant layer is too thick, curl due to curing shrinkage may occur and it may be difficult to form the heat and moisture resistant layer itself, or there may be a problem that the heat and moisture resistant layer does not cure sufficiently and instead functions as a fragile layer.

[0094] The heat- and moisture-resistant layer is typically formed by applying a composition for forming the heat- and moisture-resistant layer to the first retardation layer and curing or solidifying the coating film. Specifically, the first heat- and moisture-resistant layer is formed by applying the composition for forming the layer to the surface of the first retardation layer on the polarizer side and curing or solidifying the coating film; the second heat- and moisture-resistant layer (if present) is formed by applying the composition for forming the layer to the surface of the first retardation layer on the side opposite to the polarizer and curing or solidifying the coating film. When the heat- and moisture-resistant layer is an active energy ray-curable layer, the coating film can be cured by irradiating the coating film with active energy rays (for example, visible light, ultraviolet rays, electron beams). When the heat- and moisture-resistant layer is a thermosetting layer, the coating film can be cured by heating the coating film. When the heat- and moisture-resistant layer is a solidified layer, the coating film can be solidified by heating the coating film.

[0095] G. Image display device The polarizer with a retardation layer described in Items A to F above can be applied to an image display device. Therefore, embodiments of the present invention also include an image display device using such a polarizer with a retardation layer. Representative examples of the image display device include a liquid crystal display device and an organic EL display device. The image display device according to an embodiment of the present invention typically includes the polarizer with a retardation layer described in Items A to F above on its viewing side.

Examples

[0096] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples are based on weight.

[0097] [Production Example 1: Preparation of a heat- and moisture-resistant layer (hard coat layer)] 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 "Biscoat #300"), 70 parts of ethoxylated glycerin triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-GLY-9E"), and 3 parts of a photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad 907") were diluted with a mixed solvent of cyclopentanone / toluene to prepare a composition for forming a hard coat layer. This composition for forming a hard coat layer was applied with a wire bar at a predetermined position (for example, the first retardation layer) such that the retardation layer-attached polarizing plate had the configuration shown in Table 1 below, so that the cured thickness would be 2 μm, heated at 60°C for 1 minute, and then irradiated with ultraviolet light so that the integrated light amount would be 250 mJ / cm 2 and a hard coat layer (thickness: 2 μm) was formed. The storage elastic modulus of the obtained hard coat layer was 300 MPa. In Table 1 below, this hard coat layer is denoted as "HC1".

[0098] [Production Example 2: Preparation of heat- and humidity-resistant layer (hard coat layer)] 80 parts of polyether urethane diacrylate (manufactured by Mitsubishi Chemical Corporation, product name "UT-7314"), 20 parts of urethane acrylate (manufactured by DIC Corporation, product name "ELS-888"), 0.1 part of a leveling agent (manufactured by Kyoeisha Chemical Co., Ltd., product name "LE-303"), and 3 parts of a photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad 907") were diluted with a mixed solvent of cyclopentanone / toluene to prepare a composition for forming a hard coat layer. This composition for forming a hard coat layer was applied with a wire bar at a predetermined position (for example, the first retardation layer) such that the retardation layer-attached polarizing plate had the configuration shown in Table 1 below, so that the cured thickness would be 2 μm, heated at 60°C for 1 minute, and then irradiated with ultraviolet light so that the integrated light amount would be 250 mJ / cm 2 and a hard coat layer (thickness: 2 μm) was formed. The storage elastic modulus of the obtained hard coat layer was 1000 MPa. In Table 1 below, this hard coat layer is denoted as "HC1".

[0099] [Production Example 3: Preparation of Heat- and Moisture-Resistant Layer (UV-Curable Adhesive Layer)] 50 parts of 3,4-epoxycyclohexenylmethyl-3’,4’-epoxycyclohexene carboxylate (manufactured by Daicel Corporation, product name “Celoxide 2021P”), 50 parts of neopentyl glycol glycidyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name “Epogose NPG(D)”), and 2.25 parts of a photopolymerization initiator (manufactured by San-Apro Ltd., product name “CPI-100P”) were blended to prepare a UV-curable adhesive. The storage elastic modulus of the cured product (adhesive layer) of this ultraviolet ray was 1800 MPa. In Table 1 described later, this adhesive layer is denoted as “UV Adhesive 1”.

[0100] [Production Example 4: Preparation of Heat- and Moisture-Resistant Layer (UV-Curable Adhesive Layer)] 10 parts of an acrylic polymer (manufactured by Toagosei Co., Ltd., product name “ARUFON UP-1190”), 12.5 parts of hydroxyethyl acrylamide, 22 parts of glycerin triacrylate (manufactured by Toagosei Co., Ltd., product name “Aronix M-5700”), 12.5 parts of neopentyl glycol hydroxypivalate acrylate adduct (manufactured by Kyoeisha Chemical Co., Ltd., product name “Light Acrylate HPP-A”), 36 parts of 1,9-nonanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., product name “Light Acrylate 1,9ND-A”), 3 parts of diethyl acrylamide, 3 parts of a photopolymerization initiator (manufactured by IGM Resins, product name “Omnirad 907”), 3 parts of a photopolymerization initiator (manufactured by Nippon Kayaku Co., Ltd., product name “KAYACURE-DETX-S”), and 4 parts of a MAAPhBA masterbatch were blended to prepare a UV-curable adhesive. The storage elastic modulus of the cured product (adhesive layer) of this ultraviolet ray was 18 MPa. In Table 1 described later, this adhesive layer is denoted as “UV Adhesive 2”.

[0101] [Production Example 5: Preparation of Heat- and Moisture-Resistant Layer (UV-Curable Adhesive Layer)] 53.3 parts of unsaturated fatty acid hydroxyalkyl ester-modified ε-caprolactone (manufactured by Daicel Corporation, product name "Placcel 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 acryloylmorpholine, 13.3 parts of an acrylic polymer (manufactured by Toagosei Co., Ltd., product name "Arufon UP-1190"), 3 parts of a photopolymerization initiator (manufactured by IGM Resins, product name "Omnirad 907"), and 3 parts of a photopolymerization initiator (manufactured by Nippon Kayaku Co., Ltd., product name "KAYACURE-DETX-S") were blended to prepare an ultraviolet curable adhesive. The storage modulus of the cured product (adhesive layer) of this ultraviolet light was 2.6 MPa. In Table 1 described later, this adhesive layer is denoted as "UV Adhesive 3".

[0102] [Production Example 6: Preparation of a heat and moisture resistant layer (ultraviolet crosslinked layer of an acrylic resin)] 50 parts of 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-HD-N"), 50 parts of trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "A-TMPT"), and 10 parts of a photo-crosslinking agent (propylene glycol monomethyl ether acetate solution of an organic peroxide, solid content 20%, manufactured by NOF Corporation, product name "BTTB") were blended to prepare an ultraviolet curable composition. This ultraviolet curable composition was applied with a wire bar at a predetermined position (for example, the first retardation layer) such that the retardation layer-attached polarizing plate has the configuration shown in Table 1 described later so that the thickness after curing becomes 2 μm, heated at 50 °C for 10 minutes, and then irradiated with ultraviolet light so that the integrated light amount becomes 900 mJ / cm 2 to form an ultraviolet crosslinked layer (thickness 2 μm). The storage modulus of the obtained ultraviolet crosslinked layer was 2000 MPa. In Table 1 described later, this ultraviolet crosslinked layer is denoted as "Acrylic Film 1".

[0103] [Production Example 7: Preparation of a heat and moisture resistant layer (cured layer of an epoxy resin)] 15 parts of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YX4000"), 10 parts of 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (manufactured by Toagosei Co., Ltd., product name "OXT-221"), 2 parts of a photoacid generator (manufactured by San-Apro Ltd., product name "CPI-100P"), and 73 parts of methyl ethyl ketone were blended to prepare an ultraviolet curable composition. This ultraviolet curable composition was applied with a wire bar at a predetermined position (for example, the first retardation layer) such that the structure of the retardation film-attached polarizing plate became as shown in Table 1 described later, and the cured thickness became 2 μm, heated at 60 °C for 3 minutes, and then irradiated with ultraviolet light so that the integrated light amount became 600 mJ / cm 2 to form a cured layer (thickness 2 μm). The storage elastic modulus of the obtained cured layer was 2200 MPa. In Table 1 described later, this cured layer is denoted as "epoxy film 1".

[0104] [Production Example 8: Preparation of a heat and moisture resistant layer (cured layer of an epoxy resin)] 30 parts of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YX7200B35") and 73 parts of methyl ethyl ketone were blended to prepare an epoxy resin solution. This epoxy resin solution was applied with a wire bar at a predetermined position (for example, the first retardation layer) such that the structure of the retardation film-attached polarizing plate became as shown in Table 1 described later, and the cured thickness became 2 μm, heated at 60 °C for 3 minutes, and a cured layer (thickness 2 μm) was formed. The storage elastic modulus of the obtained cured layer was 2800 MPa. In Table 1 described later, this cured layer is denoted as "epoxy film 2".

[0105] [Production Example 9: Preparation of a retardation film constituting the first retardation layer] (Polymerization of a polyester carbonate resin) Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100 °C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluorene-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 replacing the inside of the reactor with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the internal temperature reached 100 °C. The internal temperature reached 220 °C 40 minutes after the start of temperature increase, and while controlling to maintain this temperature, reduced pressure was started and it was set to 13.3 kPa in 90 minutes after reaching 220 °C. The phenol vapor by-produced during the polymerization reaction was led to a reflux condenser at 100 °C, the monomer components contained in a small amount in the phenol vapor were returned to the reactor, and the phenol vapor that did not condense was led to a condenser at 45 °C and recovered. Nitrogen was introduced into the first reactor to repressurize to atmospheric pressure once, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Next, heating and reduced pressure in the second reactor were started, and the internal temperature was set to 240 °C and the pressure to 0.2 kPa in 50 minutes. Thereafter, the polymerization was allowed to proceed until a predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, and the produced polyester carbonate resin was extruded into water, and the strands were cut to obtain pellets.

[0106] (Production of retardation film) The obtained polyester carbonate resin (pellets) was vacuum dried at 80°C for 5 hours, and then a film forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a chill roll (set temperature: 120 - 130°C), and a winder was used to produce a long resin film with a thickness of 135 μm. 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 retardation film with a thickness of 48 μm. The Re(550) of the obtained retardation film was 141 nm, Re(450) / Re(550) was 0.82, and the Nz coefficient was 1.12. In Table 1 described later, this retardation film is denoted as "Film 1".

[0107] [Production Example 10: Preparation of a Liquid Crystal Alignment Solidification Layer Constituting the Second Retardation Layer] 20 parts by weight of a side-chain type liquid crystal polymer represented by the following chemical formula (I) (the numbers 65 and 35 in the formula represent the molar% of the monomer units and are represented as a block polymer for convenience: weight average molecular weight 5000), 80 parts by weight of a polymerizable liquid crystal showing a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal coating solution. Then, the coating solution was coated on a PET substrate subjected to vertical alignment treatment using a bar coater, and the liquid crystal was aligned by heating and drying at 80°C for 4 minutes. Ultraviolet rays were irradiated on this liquid crystal layer to cure the liquid crystal layer, thereby forming a second retardation layer (thickness 3 μm) showing a refractive index characteristic of nz>nx = ny on the substrate. The second retardation layer is transferred to a predetermined position such that the retardation layer-attached polarizing plate has the configuration shown in Table 1 described later. [Chemical formula]

[0108] [Production Example 11: Preparation of a Polarizing Plate] (Preparation of a Polarizer) As the thermoplastic resin substrate, an amorphous isophthal copolymer polyethylene terephthalate film (thickness: 100 μm) in a long strip shape with a Tg of about 75 °C was used, and one side of the resin substrate was subjected to corona treatment. 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Gohsei Chemical Industry Co., Ltd., trade name "Gosefimer") at a ratio of 9:1, and the mixture was dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60 °C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130 °C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilization bath at a liquid temperature of 40 °C (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment). Next, the laminate was immersed in a dyeing bath at a liquid temperature of 30 °C (an aqueous iodine solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the finally obtained polarizer becomes a desired value (dyeing treatment). Next, the laminate was immersed in a crosslinking bath at a liquid temperature of 40 °C (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (crosslinking treatment). Thereafter, while the laminate was immersed in an aqueous boric acid solution at a liquid temperature of 70 °C (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%), uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds so that the total stretching ratio became 5.5 times (in-water stretching treatment). Thereafter, 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 respect to 100 parts by weight of water) (washing treatment). Thereafter, while drying in an oven maintained at about 90 °C, it was brought into contact with a SUS heating roll whose surface temperature was maintained at about 75 °C (dry shrinkage treatment). In this way, a polarizer with a thickness of about 5 μm was formed on the resin substrate, and a polarizing plate having a resin substrate / polarizer configuration was obtained.

[0109] (Production of Polarizing Plate) An HC-TAC film was bonded as a visible-side protective layer to the surface of the obtained polarizer (the surface opposite to the resin substrate) via an ultraviolet-curable adhesive. The HC-TAC film is a film in which an HC layer (thickness 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness 25 μm), and it was bonded so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off to obtain a polarizing plate P1 having an HC-TAC film (visible-side protective layer) / polarizer configuration. The HC-TAC film had a shrinkage rate of 0.03% after being placed in an environment of 85°C for 240 hours.

[0110] [Production Example 12: Production of Polarizing Plate] A polarizing plate P2 having an acrylic resin film (visible-side protective layer) / polarizer configuration was obtained in the same manner as in Production Example 11, except that an acrylic resin film (thickness 20 μm) having a glutarimide structure was used instead of the HC-TAC film as the visible-side protective layer. The acrylic resin film had a shrinkage rate of 0.07% after being placed in an environment of 85°C for 240 hours.

[0111] [Production Example 13: Production of Polarizing Plate] A polarizing plate P3 having a cycloolefin resin film (visible-side protective layer) / polarizer configuration was obtained in the same manner as in Production Example 11, except that a cycloolefin resin film (manufactured by Zeonoa Co., G+ film) was used instead of the HC-TAC film as the visible-side protective layer. The cycloolefin resin film had a shrinkage rate of 0.04% after being placed in an environment of 85°C for 240 hours.

[0112] [Examples 1 to 18 and Comparative Examples 1 to 19] A polarizing plate with a retardation layer having the configuration shown in Table 1 was fabricated. The obtained polarizing plate with a retardation layer was subjected to a HAST test, which is an accelerated test for durability in a high-temperature and high-humidity environment. The HAST test was conducted in accordance with JIS C60068. Specifically, the polarizing plate with a retardation layer was placed in an oven controlled at 110 °C and 85% RH for 36 hours for heating and humidification, and the state of the polarizing plate with a retardation layer 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): Slight cracks or peeling were observed. × (Defective): Cracks were significant and / or peeling was observed.

[0113]

Table 1

[0114] [Evaluation] As is clear from Table 1, the polarizing plate with a retardation layer of the example of the present invention suppresses cracks and peeling even in a severe high-temperature and high-humidity environment.

Industrial Applicability

[0115] The polarizing plate with a retardation layer of the present invention can be suitably used in an image display device (typically, a liquid crystal display device, an organic EL display device).

Explanation of Reference Numerals

[0116] 10 Polarizing plate 11 Polarizer 12 First protective layer 13 Second protective layer 21 First retardation layer 22 Second retardation layer 31 First heat and humidity resistant layer 32 Second heat and humidity resistant layer 100 Polarizing plate with a retardation layer 101 Polarizing plate with a retardation layer

Claims

1. A polarizing plate including a polarizer, a heat and moisture resistant layer, and a retardation layer, in this order, wherein the retardation layer is composed of a stretched film of a resin film and satisfies the relationship Re(450) < Re(550), the heat and moisture resistant layer is a cured layer or a solidified layer of a resin, the heat and moisture resistant layer contains urethane acrylate and polyether urethane diacrylate, A polarizing plate with a retardation layer: 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.

2. The polarizing plate with a retardation layer according to claim 1, wherein Re(550) of the retardation layer is 100 nm to 200 nm, and the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50° or 130° to 140°.

3. Further comprising another retardation layer having a refractive index characteristic of nz > nx = ny on the side opposite to the polarizing plate of the retardation layer, wherein another heat and moisture resistant layer is provided between the retardation layer and the other retardation layer, and the other heat and moisture resistant layer is a cured layer or a solidified layer of a resin. The polarizing plate with a retardation layer according to claim 1 or 2.

4. The polarizing plate with a retardation layer according to claim 3, wherein the other heat and moisture resistant layer also functions as an adhesive layer.

5. The polarizing plate with a retardation layer according to claim 3, wherein an adhesive layer is provided between the other heat and moisture resistant layer and the other retardation layer.

6. The polarizing plate with a retardation layer according to any one of claims 1 to 5, wherein the retardation layer contains at least one bonding group selected from the group consisting of a carbonate bond and an ester bond, and at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and contains a resin having positive refractive index anisotropy: 【Chemical 1】 【Chemical 2】 In general formulas (1) and (2), R １ ~R ３ are each independently a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, R ４ ~R ９ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 10 carbon atoms, a substituted or unsubstituted acyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted aryloxy group having 1 to 10 carbon atoms, a substituted or unsubstituted amino group, a substituted or unsubstituted vinyl group having 1 to 10 carbon atoms, a substituted or unsubstituted ethynyl group having 1 to 10 carbon atoms, a sulfur atom having a substituent, a silicon atom having a substituent, a halogen atom, a nitro group, or a cyano group; provided that R ４ ~R ９ may be the same as or different from each other, and at least two adjacent groups among R ４ ~R ９ may be bonded to each other to form a ring.

7. The polarizing plate includes a protective layer on the side opposite to the retardation layer of the polarizer, and the shrinkage rate after placing the protective layer in an environment of 85°C for 240 hours is less than 0.05%. The polarizing plate with a retardation layer according to any one of claims 1 to 6.

8. The polarizing plate with a retardation layer according to claim 7, wherein the protective layer is composed of a triacetyl cellulose film or a cyclic olefin resin film.

9. An image display device including the polarizing plate with a retardation layer according to any one of claims 1 to 8.

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