Circularly polarizing plate with antireflection layer and image display device using the same

Abstract

The present application relates to a circularly polarizing plate with an antireflection layer and an image display device using the same. Provided is a circularly polarizing plate with an antireflection layer, which can realize an image display device in which color hue unevenness is suppressed. The circularly polarizing plate with an antireflection layer of the present application has: a polarizing plate including a polarizing member, an antireflection layer disposed on one side of the polarizing plate, and a phase difference layer disposed on the other side of the polarizing plate. The refractive index of the antireflection layer is 1.29-1.38, the thickness is 70 nm-120 nm, and in the range of wavelengths of 380 nm-780 nm, the wavelength at which the lowest reflectance is obtained exists in the range of 400 nm-600 nm. The Re(550) of the phase difference layer is 136 nm-200 nm.

Description

Technical Field

[0001] The present invention relates to a circular polarizer with an anti-reflective layer and an image display device using the circular polarizer with the anti-reflective layer. Background Technology

[0002] In recent years, image display devices, represented by liquid crystal displays and electroluminescent (EL) displays (such as organic EL displays and inorganic EL displays), have been rapidly gaining popularity. In image display devices, circular polarizers, which include polarizing plates and retardation plates, are sometimes used. However, when circular polarizers are applied to low-reflectivity image display devices (especially organic EL displays), there is a problem of easily visually identifiable color unevenness.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 5876441

[0006] Patent Document 2: Japanese Patent Application Publication No. 2014-026266 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The present invention was made to solve the above-mentioned problems, and its main objective is to provide a circular polarizer with an anti-reflective layer for an image display device that can suppress hue asymmetry.

[0009] Solution for solving the problem

[0010] The circular polarizing plate with an anti-reflective layer according to an embodiment of the present invention comprises: a polarizing element, an anti-reflective layer disposed on one side of the polarizing element, and a phase retardation layer disposed on the other side of the polarizing element. The anti-reflective layer has a refractive index of 1.29 to 1.38, a thickness of 70 nm to 120 nm, and the wavelength at which the lowest reflectivity is obtained exists in the range of 400 nm to 600 nm within the wavelength range of 380 nm to 780 nm. The Re(550) of the phase retardation layer is 136 nm to 200 nm.

[0011] In one embodiment, the reflectivity of the anti-reflective layer is less than 1.5%.

[0012] In one embodiment, the angle between the slow axis of the phase difference layer and the absorption axis of the polarizer is 40° to 50° or 130° to 140°.

[0013] In one embodiment, the phase retardation layer is composed of a stretched film of resin film, with Re(450) / Re(550) being 0.97 to 1.03. Here, Re(450) and Re(550) are the in-plane phase differences measured at 23°C using light with wavelengths of 450 nm and 550 nm, respectively.

[0014] According to another aspect of the present invention, an image display device is provided. This image display device includes the aforementioned circular polarizer with an anti-reflective layer on the visual recognition side. The circular polarizer with the anti-reflective layer is configured such that the anti-reflective layer becomes the visual recognition side. The reflectivity of the image display device is 40% or less.

[0015] In one embodiment, the image display device is an organic electroluminescent display device.

[0016] The effects of the invention

[0017] According to an embodiment of the present invention, when a circular polarizer is applied to an image display device, by providing an anti-reflective layer on the side that serves as the visual recognition side, and by combining and optimizing the refractive index, thickness, and wavelength that achieves the lowest reflectivity in the visible light region of the anti-reflective layer, thereby optimizing the in-plane phase difference of the phase difference layer, a circular polarizer with an anti-reflective layer capable of suppressing hue asymmetry in an image display device can be obtained. Furthermore, this circular polarizer with an anti-reflective layer can also achieve high transmittance in addition to the aforementioned effects. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view of a circular polarizing plate with an anti-reflective layer according to one embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] 10 polarizing plates

[0021] 11 polarizer

[0022] 12 First protective layer

[0023] 13 Second protective layer

[0024] 30 Anti-reflective layer

[0025] 40 phase difference layers

[0026] 100 Circular polarizing plate with anti-reflective layer Detailed Implementation

[0027] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0028] (Definitions of terms and symbols)

[0029] The definitions of terms and symbols in this specification are as follows.

[0030] (1) Refractive index (nx, ny, nz)

[0031] “nx” is the refractive index in the direction where the refractive index reaches its maximum in the plane (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.

[0032] (2) In-plane phase difference (Re)

[0033] “Re(λ)” is the in-plane phase difference of a thin film measured at 23°C using light with a wavelength of λ nm. For example, “Re(450)” is the in-plane phase difference of a thin film measured at 23°C using light with a wavelength of 450 nm. When the thickness of the thin film is denoted as d (nm), Re(λ) is obtained by the formula Re = (nx - ny) × d.

[0034] (3) Phase difference (Rth) in the thickness direction

[0035] “Rth(λ)” is the phase difference in the thickness direction of the thin film measured at 23℃ using light with a wavelength of λnm. For example, “Rth(450)” is the phase difference in the thickness direction of the thin film measured at 23℃ using light with a wavelength of 450nm. When the thickness of the thin film is denoted as d (nm), Rth(λ) is obtained by the formula Rth=(nx-nz)×d.

[0036] (4) Nz coefficient

[0037] The Nz coefficient is obtained by Nz = Rth / Re.

[0038] (5) Angle

[0039] When an angle is mentioned in this manual, unless otherwise specified, the angle includes both clockwise and counterclockwise directions.

[0040] A. The overall structure of a circular polarizing plate with an anti-reflective layer

[0041] Figure 1This is a schematic cross-sectional view of a circular polarizer with an anti-reflective layer according to an embodiment of the present invention. The circular polarizer 100 with an anti-reflective layer shown in the figure includes: a polarizer 10, an anti-reflective layer 30 disposed on one side of the polarizer 10 (e.g., the side opposite to the image display unit, i.e., the visual recognition side, when applied to an image display device), and a phase retardation layer 40 disposed on the other side of the polarizer 10 (e.g., the image display unit side, when applied to an image display device). The anti-reflective layer 30 and the phase retardation layer 40 are respectively adhered to the polarizer 10 by any suitable adhesive layer or bonding agent layer (not shown). The polarizer 10 includes: a polarizer 11, a first protective layer 12 disposed on one side of the polarizer 11 (the anti-reflective layer side), and a second protective layer 13 disposed on the other side of the polarizer 11 (the phase retardation layer side). Depending on the purpose, one or both of the first protective layer 12 and the second protective layer 13 may be omitted. For example, the phase retardation layer 30 can also function as a protective layer for the polarizer 11, thus the second protective layer 13 can be omitted. Furthermore, when the anti-reflective layer is typically formed on the substrate as described later, the substrate / anti-reflective layer laminate sometimes functions as a protective layer. In this case, the first protective layer 12 can be omitted. The substrate / anti-reflective layer laminate may further include a hard coating. Therefore, a polarizer with an anti-reflective layer can be configured to omit the two protective layers and have a polarizer 11, an anti-reflective layer 30 disposed on one side of the polarizer 11, and a phase retardation layer 40 disposed on the other side of the polarizer 11 (this configuration includes configurations where protective layers are included on one or both sides of the polarizer). In practical terms, an appropriate adhesive layer 50 is provided as the outermost layer on the side of the phase retardation layer 40 opposite to the polarizer 10, allowing the circular polarizer with the anti-reflective layer to be adhered to the image display unit.

[0042] In embodiments of the present invention, the antireflective layer has a refractive index of 1.29 to 1.38, a thickness of 70 nm to 120 nm, and a wavelength (hereinafter sometimes referred to as the bottom wavelength) with the lowest reflectivity in the wavelength range of 380 nm to 780 nm exists in the range of 400 nm to 600 nm. By combining and optimizing the refractive index, thickness, and bottom wavelength of the antireflective layer in this way, an image display device in which hue asymmetry is suppressed can be realized. Details regarding the antireflective layer are described below in section E.

[0043] The retardation layer 40 is typically composed of a stretched film of resin film. The Re(550) of the retardation layer 40 is typically 136 nm to 200 nm. The Re(450) / Re(550) ratio of the retardation layer is preferably 0.97 to 1.03. The angle between the slow axis of the retardation layer and the absorption axis of the polarizer 11 is preferably 40° to 50°, more preferably 42° to 48°, even more preferably 44° to 46°, and particularly preferably about 45°; or, preferably 130° to 140°, more preferably 132° to 138°, even more preferably 134° to 136°, and particularly preferably about 135°.

[0044] In one embodiment, the circular polarizer with the anti-reflective layer may further have an additional phase retardation layer (not shown) between the phase retardation layer 40 and the adhesive layer 50. This additional phase retardation layer is characterized by a refractive index characteristic showing a relationship of nz > nx = ny. By providing this additional phase retardation layer, oblique reflections can be effectively prevented, achieving a wide viewing angle for the anti-reflective function.

[0045] In one embodiment, the circular polarizer with an anti-reflective layer may further have a conductive layer or an isotropic substrate (not shown) with a conductive layer. When a conductive layer or an isotropic substrate with a conductive layer is provided, the circular polarizer with an anti-reflective layer can be applied to a so-called inner touch panel type input display device in which a contact sensor is assembled between an image display unit (e.g., an organic EL unit) and the polarizer. The conductive layer or isotropic substrate with a conductive layer is typically disposed between the phase retardation layer 40 and the adhesive layer 50. When other phase retardation layers are provided, the other phase retardation layers and the conductive layer or isotropic substrate with a conductive layer are typically disposed sequentially from the phase retardation layer 40 side.

[0046] A circular polarizer with an anti-reflective layer can have a further retardation layer (not shown). This further retardation layer can be combined with other retardation layers or set alone (i.e., without other retardation layers). The optical properties (e.g., refractive index, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, and placement of the further retardation layer can be appropriately set according to the purpose.

[0047] The circular polarizer with an anti-reflective layer can be a single sheet or a strip. In this specification, "strip" refers to a long, slender shape whose length is sufficiently long relative to its width, for example, including a long, slender shape whose length is 10 times or more, preferably 20 times or more, than its width. The strip-shaped circular polarizer with the anti-reflective layer can be rolled into a roll.

[0048] In practice, it is preferable to temporarily attach a release film to the surface of the adhesive layer 50 until the circular polarizer with the anti-reflective layer is ready for use. By temporarily attaching the release film, a roll of the circular polarizer with the anti-reflective layer can be formed while protecting the adhesive layer.

[0049] The following describes the components of a circular polarizing plate with an anti-reflective layer.

[0050] B. Polarizing components

[0051] As the polarizing element 11, any suitable polarizing element can be used. For example, the resin film forming the polarizing element can be a single-layer resin film or a laminate of two or more layers.

[0052] Specific examples of polarizers composed of a single-layer resin film include: polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films using dichroic substances such as iodine and dichroic dyes; and polyene-oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA films with iodine and uniaxially stretching them are preferred.

[0053] The aforementioned iodine-based dyeing is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or during dyeing. Alternatively, dyeing can be performed after stretching. Depending on the needs, the PVA-based film may undergo swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. For example, by immersing the PVA-based film in water for washing before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA-based film be removed, but the PVA-based film can also swell to prevent uneven dyeing.

[0054] Specific examples of polarizing elements obtained using a laminate include: polarizing elements obtained using a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizing element obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured by the following steps: for example, coating a PVA-based resin solution onto a resin substrate, allowing it to dry to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizing element from the PVA-based resin layer. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and then stretching it. Furthermore, if necessary, stretching may also include air stretching the laminate at a high temperature (e.g., above 95°C) before stretching in the aqueous boric acid solution. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface for use. Details of this method for manufacturing polarizers are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The descriptions in these patent documents are incorporated herein by reference.

[0055] The polarizing element is preferably composed of a single-layer resin film. With this configuration, a circular polarizer with an anti-reflective layer can be obtained through optimized synergistic effects with the first and second adhesive layers, suppressing phase difference unevenness under high-temperature conditions.

[0056] The thickness of the polarizing element is preferably about 1 μm to 30 μm, more preferably about 5 μm to 25 μm. In particular, to obtain a polarizing element with a thickness of 10 μm or less, a manufacturing method for a thin polarizing element disclosed in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455, which uses a polyvinyl alcohol-based film containing a film formed on a thermoplastic resin substrate as a laminate of the aforementioned polyvinyl alcohol-based film, can be applied. If the thickness of the polarizing element is within this range, warping during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0057] The polarizer preferably exhibits absorption dichroism at any wavelength within the range of 380 nm to 780 nm. The transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0058] C. Protective layer

[0059] The first protective layer 12 and the second protective layer 13 are each formed from any suitable thin film that can be used as a protective layer for a polarizing element. Specific examples of materials that are the main components of the thin film include cellulose resins such as cellulose triacetate (TAC); transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic acid, and acetate. Furthermore, thermosetting or UV-curing resins such as (meth)acrylic acid, urethane, (meth)acrylate urethane, epoxy, and silicone resins can also be used. In addition, glassy polymers such as siloxane polymers can also be used. Furthermore, polymer films described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As the material for this film, resin compositions can be used, for example, thermoplastic resins containing substituted or unsubstituted imide groups on the side chains and thermoplastic resins containing substituted or unsubstituted phenyl and nitrile groups on the side chains. Examples include resin compositions having alternating copolymers formed from isobutylene and N-methylmaleimide, and acrylonitrile-styrene copolymers. The polymer film can be, for example, an extruded product of the above-described resin compositions.

[0060] The circular polarizer with an anti-reflective layer, as described below, is typically disposed on the visual recognition side of an image display device, and the first protective layer 12 is typically disposed on its visual recognition side. Therefore, the first protective layer 12 can be subjected to surface treatments such as hard coating, anti-reflective treatment, anti-adhesion treatment, and anti-glare treatment as needed. Furthermore / or, the first protective layer 12 can be subjected to treatments to improve visual recognition when viewed through polarized sunglasses (typically, imparting (elliptical) polarization or ultra-high phase difference). By implementing such treatments, excellent visual recognition can be achieved even when viewing the displayed image through polarized lenses such as polarized sunglasses. Therefore, the circular polarizer with an anti-reflective layer can also be suitable for use in image display devices that can be used outdoors.

[0061] 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. It should be noted that, when surface treatment is performed, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

[0062] In one embodiment, the second protective layer 13 is preferably optically isotropic. In this specification, "being 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.

[0063] D. Retardation layer

[0064] The in-plane retardation Re(550) of the retardation layer is as described above, and is typically 136 nm to 200 nm, preferably 136 nm to 180 nm, more preferably 136 nm to 160 nm, and still more preferably 136 nm to 150 nm. That is, the retardation layer can function as a so-called λ / 4 plate. Further, by making Re(550) of the retardation layer 136 nm or more, an image display device having a very excellent reflected hue and a small light reflectance (Y value) can be realized.

[0065] The retardation layer typically shows a flat wavelength dependence in which the retardation value is substantially constant regardless of the wavelength of the measurement light. Re(450) / Re(550) of the retardation layer is preferably 0.97 to 1.03, more preferably 0.98 to 1.02. Re(650) / Re(550) of the retardation layer is preferably 0.97 to 1.03, more preferably 0.98 to 1.02.

[0066] The retardation layer has an in-plane retardation as described above, and thus has a relationship of nx > ny. As long as the retardation layer has a relationship of nx > ny, it shows any appropriate refractive index characteristics. The refractive index characteristics of the retardation layer typically show a relationship of nx > ny ≥ nz. It should be noted that "ny = nz" here includes not only the case where ny and nz are exactly equal, but also the case where they are substantially equal. Therefore, within the range that does not impair the effects of the present invention, there may be a case where ny < nz. The Nz coefficient of the retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and still more preferably 0.9 to 1.2. By satisfying this relationship, when a circular polarizing plate with an antireflection layer is used for an image display device, a very excellent reflected hue can be realized.

[0067] The thickness of the retardation layer can be set in such a way that it can function most appropriately as a λ / 4 plate. In other words, the thickness can be set in such a way as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 70 μm or less, and preferably 45 μm to 60 μm. If the thickness of the retardation layer is within this range, warping during heating can be well suppressed, and warping during bonding can be well adjusted.

[0068] The absolute value of the photoelastic coefficient of the retardation layer is preferably 20×10 -12 (m2 / N) or less, more preferably 1.0×10 -12 (m 2 / N)~15×10 -12 (m 2 / N), further preferably 2.0×10 -12 (m 2 / N)~12×10 -12 (m 2 / N). If the absolute value of the photoelastic coefficient is within this range, then when a circular polarizer with an anti-reflective layer is applied to an image display device, display unevenness can be suppressed.

[0069] The retardation layer can be composed of any suitable resin film capable of satisfying the above-mentioned characteristics. Representative examples of such resins include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyaryl ester resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, and acrylic resins. These resins can be used alone or in combination (e.g., blending, copolymerizing). The retardation layer can typically be composed of cyclic olefin resins, polycarbonate resins, or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins).

[0070] As a representative example of cyclic olefin resins, norbornene resins can be cited. Norbornene resins are resins polymerized by polymerizing norbornene monomers as polymerization units. Examples of such norbornene monomers include, for instance, norbornene and its alkyl and / or alkylidene substituted derivatives, such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethide-2-norbornene, and their halogenated or other polar group substituted derivatives; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc.; dimethyl octahydronaphthalene, etc. Alkyl and / or alkylidene substituted derivatives, and polar group substituted derivatives such as halogens, for example, 6-methyl-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethidene-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a- Octahydronaphthalene, 6-chloro-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:5,8-dimethyl- 1,4,4a,5,6,7,8,8a-octahydronaphthalene, etc.; 3- to 4-polymers of cyclopentadiene, such as 4,9:5,8-dimethyl-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzo[a]indene, 4,11:5,10:6,9-trimethyl-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecylhydro-1H-cyclopentanethracene, etc. The above norbornene-based resins can be copolymers of norbornene monomers with other monomers.

[0071] As a polymerization unit in norbornene resins, other cyclic olefins capable of ring-opening polymerization can be used in combination. Specific examples of such cyclic olefins include compounds with one reactive double bond, such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

[0072] The number-average molecular weight (Mn) of the aforementioned cyclic olefin resin, as determined by gel permeation chromatography (GPC) using toluene solvent, is preferably 25,000 to 200,000, more preferably 30,000 to 100,000, and most preferably 40,000 to 80,000. If the number-average molecular weight is within the above range, excellent mechanical strength, good solubility, good formability, and good casting operability can be achieved.

[0073] Commercially available films can be used as the aforementioned cyclic olefin resin films. Specific examples include the products manufactured by ZEON Corporation under the trade names "ZEONEX" and "ZEONOR"; JSR Corporation under the trade name "Arton"; TICNA Corporation under the trade name "TOPAS"; and Mitsui Chemicals Corporation under the trade name "APEL".

[0074] The polycarbonate resins described above are representative of those containing structural units derived from dihydroxy compounds having the bonding structure shown in formula (I).

[0075]

[0076] Examples of dihydroxy compounds include those represented by formula (II) below. Examples of such dihydroxy compounds include isosorbide, isomannitol, and ISOIDET, which are stereoisomers. They can be used alone or in combination of two or more.

[0077]

[0078] The above-mentioned dihydroxy compounds can be used in combination with other dihydroxy compounds. Examples of other dihydroxy compounds include, for instance, alicyclic dihydroxy compounds represented by formula (III) below.

[0079] HOCH2-R 1 -CH2OH···(III)

[0080] In equation (III), R 1 This indicates a cycloalkylene group with 4 to 20 carbon atoms. Alicyclic dihydroxy compounds can be, for example, tricyclic decanediethanol or pentacyclic pentadecanediethanol. They include R in formula (III). 1 The various isomers are represented by the following formula (IV) (where n represents 0 or 1).

[0081]

[0082] In one embodiment, the polycarbonate resin comprises the structural unit shown in formula (V). That is, the polycarbonate resin may be a copolymer of diphenyl carbonate, isosorbide, and tricyclodecanediethanol.

[0083]

[0084] Details of such polycarbonate resins are described, for example, in Japanese Patent Application Publication No. 2012-031370, the contents of which are incorporated herein by reference.

[0085] The glass transition temperature of polycarbonate resins is preferably 110°C or higher and 250°C or lower, more preferably 120°C or higher and 230°C or lower. If the glass transition temperature is too low, the heat resistance tends to deteriorate, and dimensional changes may occur after film formation. If the glass transition temperature is too high, the forming stability of the film during forming may sometimes deteriorate, and in addition, the transparency of the film may be impaired. It should be noted that the glass transition temperature is determined according to JIS K 7121 (1987).

[0086] The molecular weight of polycarbonate resins can be expressed using reduced viscosity. Reduced viscosity is measured using a Ubbelohde viscometer at a temperature of 20.0℃ ± 0.1℃, with the resin concentration precisely adjusted to 0.6 g / dL using dichloromethane as a solvent. The lower limit of reduced viscosity is typically preferably 0.30 dL / g, more preferably 0.35 dL / g or higher. The upper limit of reduced viscosity is typically preferably 1.20 dL / g, more preferably 1.00 dL / g, and even more preferably 0.80 dL / g. If the reduced viscosity is less than the aforementioned lower limit, the mechanical strength of the molded article may decrease. On the other hand, if the reduced viscosity is greater than the aforementioned upper limit, reduced flowability, lower productivity, and reduced formability during molding may occur.

[0087] As a polycarbonate resin film, commercially available films can be used. Specific examples of commercially available products include "PUREACE WR-S", "PUREACE WR-W", and "PUREACE WR-M" manufactured by Teijin Corporation; and "NRF" manufactured by Nitto Denko Corporation.

[0088] The retardation layer is obtained, for example, by stretching a film formed from the aforementioned resin. Any suitable forming process can be used to form the resin film. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, casting coating (e.g., tape casting), calendering, and hot pressing. Extrusion molding or casting coating is preferred because it improves the smoothness of the resulting film and achieves good optical uniformity. The forming conditions can be appropriately set according to the composition and type of the resin used, and the desired characteristics of the retardation layer. It should be noted that, as mentioned above, various resin film products are commercially available; therefore, these commercially available films can also be directly subjected to stretching processing.

[0089] The thickness of the resin film (unstretched film) can be set to any appropriate value based on the desired thickness of the retardation layer, desired optical properties, stretching conditions (described later), etc. Preferably, it is 50 μm to 300 μm.

[0090] The stretching described above can be performed using any appropriate stretching method and conditions (e.g., stretching temperature, stretching ratio, stretching direction). Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinkage, and fixed-end shrinkage can be used individually, or 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 oblique direction. The stretching temperature relative to the glass transition temperature (Tg) of the resin film is preferably Tg-30℃ to Tg+60℃, more preferably Tg-10℃ to Tg+50℃.

[0091] By appropriately selecting the stretching method and stretching conditions described above, it is possible to obtain a phase difference film with the desired optical properties (e.g., refractive index characteristics, in-plane phase difference, Nz coefficient).

[0092] In one embodiment, the phase retardation film can be fabricated by unidirectional stretching of a resin film or unidirectional stretching at a fixed end. A specific example of unidirectional stretching at a fixed end is a method in which the resin film is moved along its length while being stretched along its width (lateral direction). The stretching ratio is preferably 1.1 to 3.5 times.

[0093] In another embodiment, the retardation film can be manufactured by continuously stretching a strip-shaped resin film obliquely along an angle θ relative to its long side. By employing oblique stretching, a strip-shaped stretched film with an orientation angle θ relative to the long side of the film (having a slow axis in the direction of angle θ) can be obtained. For example, when laminating with a polarizing film, roll-to-roll lamination can be used, simplifying the manufacturing process. It should be noted that angle θ can be the angle between the absorption axis of the polarizing film and the slow axis of the retardation layer in the polarizing plate with the retardation layer. As described above, angle θ is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°.

[0094] Tensioning machines used for oblique stretching can be categorized as, for example, tenter-type stretching machines capable of applying conveying, stretching, or traction forces at different speeds in the transverse and / or longitudinal directions. Tensioning machines include transverse unidirectional stretching machines and simultaneous bidirectional stretching machines; any suitable stretching machine can be used as long as it can continuously stretch long strips of resin film obliquely.

[0095] By appropriately controlling the left and right speeds in the stretching machine, a phase difference layer (essentially a strip-shaped phase difference film) with the desired in-plane phase difference and a slow axis in the desired direction can be obtained.

[0096] The stretching temperature of the aforementioned film can be varied depending on the desired in-plane phase difference value and thickness of the retardation layer, the type of resin used, the film thickness, and the stretching ratio. Specifically, the stretching temperature is preferably Tg-30℃ to Tg+30℃, more preferably Tg-15℃ to Tg+20℃, and most preferably Tg-10℃ to Tg+15℃. By stretching at this temperature, a retardation layer with suitable characteristics as described in this invention can be obtained. It should be noted that Tg is the glass transition temperature of the constituent material of the film.

[0097] E. Anti-reflective layer

[0098] The anti-reflective layer 30 is typically a cured layer of an ionizing radiation-curing resin composition. By incorporating the anti-reflective layer, high transmittance that is difficult to achieve with a circular polarizer alone can be obtained.

[0099] The refractive index of the antireflective layer is, as described above, 1.29 to 1.38, preferably 1.30 to 1.37, and more preferably 1.30 to 1.36. If the refractive index of the antireflective layer is within this range, an image display device in which hue asymmetry is suppressed can be achieved by combining and optimizing the thickness and bottom wavelength.

[0100] The thickness of the anti-reflective layer is, as described above, 70 nm to 120 nm, preferably 75 nm to 110 nm, and more preferably 75 nm to 100 nm. If the thickness of the anti-reflective layer is within this range, an image display device with suppressed hue asymmetry can be achieved by combining and optimizing the refractive index and bottom wavelength. If the thickness of the anti-reflective layer is too large, when a circular polarizer with an anti-reflective layer is applied to an image display device, sometimes the reflected hue becomes too blue, and / or the light reflectance (Y value) becomes too large.

[0101] The bottom wavelength of the antireflective layer, as described above, exists in the range of 400nm to 600nm, preferably in the range of 410nm to 580nm, and more preferably in the range of 420nm to 550nm. If the bottom wavelength of the antireflective layer is within this range, an image display device in which hue asymmetry is suppressed can be achieved by combining and optimizing the thickness and refractive index. If the bottom wavelength deviates from the range, when a circular polarizer with an antireflective layer is applied to an image display device, the reflected hue sometimes becomes too blue, and / or the light reflectance (Y value) becomes too large.

[0102] The reflectivity of the antireflective layer at the bottom wavelength is preferably 1.5% or less, more preferably 1.3% or less, and even more preferably 1.0% or less. Lower reflectivity is preferred, with a lower limit of, for example, 0.2%. If the reflectivity is within this range, it is possible to prevent the reflection of external light.

[0103] The ionizing radiation-curing resin composition comprises an ionizing radiation-curing resin. The ionizing radiation-curing resin composition may further comprise, depending on the purpose, a reactive diluent, a fluorine-containing additive, hollow particles, and / or solid particles.

[0104] Representative examples of ionizing radiation-curing resins include thermosetting resins, ultraviolet-curing resins, light (visible light)-curing resins, and electron beam-curing resins. Examples of ionizing radiation-curing resins include silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiol polyene resins. Furthermore, ionizing radiation-curing resins can be curable compounds containing acrylate and / or methacrylate groups that cure by heat, light (ultraviolet light, etc.), or electron beams. Specific examples include oligomers or prepolymers of acrylates and / or methacrylates, which are polyfunctional compounds such as polyols. Ionizing radiation-curing resins can be used alone or in combination of two or more.

[0105] The weight-average molecular weight of ionizing radiation-cured resins before curing can be, for example, 100 or more, 300 or more, 500 or more, 1000 or more, or 2000 or more, or below 100,000, 70,000, 50,000, 30,000, or 10,000. If the weight-average molecular weight before curing is high, the hardness will decrease; on the other hand, it tends to be less prone to cracking when bent. If the weight-average molecular weight before curing is low, there is a tendency for increased intermolecular cross-linking density and higher hardness.

[0106] Reactive diluents are typically those containing acrylate groups and / or methacrylate groups. For example, the reactive diluent described in Japanese Patent Application Publication No. 2008-88309 can be used. Specific examples of reactive diluents include monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, and polyfunctional methacrylates. Trifunctional or higher acrylates and methacrylates are preferred. Examples of reactive diluents include, for example, butanediol glycerol ether diacrylate, isocyanuric acid acrylate, and isocyanuric acid methacrylate. Reactive diluents can be used alone or in combination of two or more.

[0107] As a fluorine-containing additive, any suitable compound can be used. The fluorine-containing additive can be, for example, an organic compound or an inorganic compound containing fluorine in its molecule. Examples of organic compounds include, for example, fluorine-containing antifouling coatings, fluorine-containing acrylic compounds, and fluorine / silicone-containing acrylic compounds. Commercially available organic compounds can be used. Specific examples include "KY-1203" manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "MEGAFAC" manufactured by DIC Co., Ltd. As an inorganic compound, any suitable fluorine-containing inorganic compound can be used.

[0108] The amount of fluorine-containing additives relative to 100 parts by weight of the ionizing radiation-cured resin can be, for example, more than 0.05 parts by weight, more than 0.1 parts by weight, more than 0.15 parts by weight, more than 0.20 parts by weight, or more than 0.25 parts by weight, or less than 20 parts by weight, less than 15 parts by weight, less than 10 parts by weight, less than 5 parts by weight, or less than 3 parts by weight.

[0109] As hollow particles, any suitable hollow particles can be used. Specific examples include silica particles, acrylic particles, and acrylic-styrene copolymer particles. Commercially available hollow particles can be used. Specific examples of commercially available silica particles include those manufactured by Nippon Kaisha Chemical Industry Co., Ltd. under the trade names "THRULYA 5320" and "THRULYA 4320". The weight-average particle size of the hollow particles can be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, or 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. As for the shape of the hollow particles, any suitable shape can be adopted. The shape of the hollow particles can be, for example, a generally spherical shape in the form of beads, or an irregular shape such as powder. A generally spherical shape is preferred, a generally spherical shape with an aspect ratio of 1.5 or less is more preferred, and a substantially perfect sphere shape is even more preferred. By blending hollow particles, an antireflective layer with low refractive index and good antireflective properties can be obtained. The amount of hollow particles blended relative to 100 parts by weight of the ionizing radiation-curing resin can be, for example, 30 parts by weight or more, 50 parts by weight or more, 70 parts by weight or more, 90 parts by weight or more, or 100 parts by weight or less, or less than 300 parts by weight, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or less than 180 parts by weight. If the blending amount is within this range, an antireflective layer with excellent mechanical properties and low refractive index can be obtained.

[0110] As solid particles, any suitable solid particles can be used. Specific examples include silica particles, zirconium oxide particles, and titanium particles. Commercially available products can be used as solid particles. Specific examples of commercially available silica particles include those manufactured by Nissan Chemical Industries, Ltd. under the trade names "MEK-2140Z-AC," "MIBK-ST," and "IPA-ST." The weight-average particle size of the solid particles can be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, or it can be 3300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. As for the shape of the solid particles, any suitable shape can be adopted. The shape of the solid particles can be, for example, a generally spherical bead shape, or an irregular shape such as powder. A generally spherical shape is preferred, a generally spherical shape with an aspect ratio of 1.5 or less is more preferred, and a substantially perfect sphere shape is even more preferred. By blending solid particles, the fluorine-containing additives tend to be more concentrated on the surface of the antireflective layer, resulting in an antireflective layer with low refractive index and good antireflective properties. The amount of solid particles relative to 100 parts by weight of the ionizing radiation-curing resin can be, for example, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more, or it can be less than 150 parts by weight, less than 120 parts by weight, less than 100 parts by weight, or less than 80 parts by weight. If the blending amount is within this range, an antireflective layer with an excellent balance of mechanical properties, refractive index, and transparency can be obtained.

[0111] An antireflective layer can be typically formed by the following manufacturing method: applying an antireflective layer forming coating liquid obtained by diluting an ionizing radiation curable resin composition with a diluent solvent; drying the coating film; and curing the dried coating film.

[0112] As a diluent, any suitable solvent can be used depending on the ionizing radiation curing resin. Examples of diluents include alcohols such as methanol, ethanol, isopropanol, butanol, TBA (tert-butanol), and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, MIBK (methyl isobutyl ketone), and cyclopentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, and PMA (propylene glycol monomethyl ether acetate); ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolvers such as ethyl cellosolvers and butyl cellosolvers; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. Diluents can be used alone or in combination of two or more. By mixing multiple solvents in any suitable ratio appropriate to the purpose, the polarity can be adjusted.

[0113] The diluent can be, for example, a mixed solvent containing MIBK and PMA. The mixing ratio can be appropriately set according to the purpose. Regarding the mixing ratio, relative to 100 parts by weight of MIBK, the amount of PMA can be, for example, 20 parts by weight or more, 50 parts by weight or more, 100 parts by weight or more, 150 parts by weight or more, or 200 parts by weight or less, or less than 400 parts by weight, less than 350 parts by weight, less than 300 parts by weight, or less than 250 parts by weight.

[0114] The diluent can be, for example, a mixture of MIBK and PMA containing TBA. The mixing ratio can be appropriately set according to the purpose. Regarding the mixing ratio, relative to 100 parts by weight of MIBK, PMA can be, for example, 10 parts by weight or more, 30 parts by weight or more, 50 parts by weight or more, 80 parts by weight or more, or 100 parts by weight or more, or it can be less than 200 parts by weight, less than 180 parts by weight, less than 150 parts by weight, less than 130 parts by weight, or less than 110 parts by weight; TBA can be, for example, 10 parts by weight or more, 30 parts by weight or more, 50 parts by weight or more, 80 parts by weight or more, or it can be less than 200 parts by weight, less than 180 parts by weight, less than 150 parts by weight, less than 130 parts by weight, or less than 110 parts by weight.

[0115] The concentration of solids in the coating solution can be set to, for example, 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, 1.0% by weight or more, or 1.5% by weight or less, or 20% by weight or less, 15% by weight or less, 10% by weight or less, 5% by weight or less, or 3% by weight or less. If the concentration of solids is within this range, both coatability (e.g., wetting, leveling) and poor appearance of the coating film (e.g., uneven drying, whitening) can be prevented.

[0116] A curing agent may be added to the coating solution as needed. Any suitable polymerization initiator (e.g., thermal polymerization initiator, photopolymerization initiator, etc.) may be used as the curing agent. The amount of curing agent added relative to 100 parts by weight of the ionizing radiation curable resin may be, for example, 0.5 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight or more, or less than 15 parts by weight, less than 13 parts by weight, less than 10 parts by weight, less than 7 parts by weight, or less than 5 parts by weight.

[0117] A typical anti-reflective layer is formed on any suitable substrate and then laminated onto a polarizing element or polarizing plate using any suitable adhesive or bonding agent layer. First, a coating liquid is applied to the substrate. Any suitable method can be used for coating. Specific examples include fountain coat method, mold coating, spin coating, spray coating, gravure coating, roller coating, and bar coating. The amount of coating liquid applied can be appropriately set according to the desired thickness of the anti-reflective layer. The resulting anti-reflective layer thickness can be, for example, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, or less than 50 μm, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less.

[0118] Next, the applied coating liquid is dried to form a coating film. The drying temperature can be appropriately set according to the purpose. For example, the drying temperature can be above 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, or below 200°C, 190°C, 180°C, 170°C, 160°C, 150°C, 140°C, 135°C, 130°C, 120°C, or 110°C. Furthermore, the drying time can also be appropriately set according to the purpose. For example, the drying time can be above 30 seconds, 40 seconds, 50 seconds, or 60 seconds, or below 150 seconds, 130 seconds, 110 seconds, or 90 seconds.

[0119] Next, the coating is cured. Curing can be carried out by, for example, heating or light irradiation. The light used for irradiation can be, for example, ultraviolet light or visible light. The light source for irradiation can be, for example, a high-pressure mercury lamp. The irradiation dose of the energy source in ultraviolet curing, measured by the cumulative exposure at an ultraviolet wavelength of 365 nm, is preferably 50 mJ / cm². 2 ~500mJ / cm 2 If the radiation dose is 50 mJ / cm 2 The above conditions facilitate thorough curing, resulting in a higher hardness of the anti-reflective layer. If the irradiation dose is 500 mJ / cm²,... 2 The following can prevent the formation of color in the anti-reflective layer.

[0120] F. Image display device

[0121] The circular polarizer with an anti-reflective layer described in items A to E above can be applied to image display devices. Therefore, embodiments of the present invention also include image display devices using such a circular polarizer with an anti-reflective layer. A representative example of the image display device described in the embodiments of the present invention is that it has the circular polarizer with an anti-reflective layer described in items A to E above on its visual recognition side. The circular polarizer with the anti-reflective layer is configured such that the anti-reflective layer is on the visual recognition side. The reflectivity of the image display device is preferably 40% or less. In an image display device with such reflectivity, the effect of the circular polarizer with an anti-reflective layer described in items A to E above becomes significant. Specifically, as shown below. If the reflectivity of the image display device is low, reflections of the displayed image can be reduced; on the other hand, color unevenness is easily visually discernible. According to embodiments of the present invention, by optimizing the configuration of the circular polarizer with an anti-reflective layer, an image display device with low reflections of the displayed image and suppressed color unevenness can be achieved. Representative examples of image display devices include liquid crystal display devices and organic electroluminescent (EL) display devices. Organic EL display devices are preferred.

[0122] The light reflectance of the image display device is preferably 1.5% or less, more preferably 1.2% or less. Light reflectance refers to the reflectance of the Y value in the XYZ chromaticity system, measured according to JIS Z 8722. The reflected hue b of the image display device... * The preferred value is -15 to -6, more preferably -14 to -8. Reflected hue b * The value refers to L * a * b * b in the color system * The value is determined according to JIS Z 8722:2009 (spectrophotometer). This light reflectance and reflected hue can be achieved by using the circular polarizing plate with an anti-reflection layer described in items A to E above.

[0123] Example

[0124] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. It should be noted that the methods for measuring each characteristic are as follows.

[0125] (1) Reflectivity

[0126] For the antireflective layer used in the examples and comparative examples, the frontal reflectance was measured using a spectrophotometer "CM-2600d" manufactured by KONICA MINOLTA. The frontal reflectance was measured using the SCI method. The wavelength of the measurement light was varied between 380 nm and 780 nm, and the wavelength at which the lowest reflectance was observed was taken as the bottom wavelength, and the reflectance at the bottom wavelength was taken as the bottom reflectance.

[0127] (2) Thickness

[0128] The measurements were performed using an interferometric film thickness gauge (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000").

[0129] (3) Refractive index

[0130] Measurements were performed using a prism coupler SPA-4000 (manufactured by Sailun Technology).

[0131] (4) In-plane phase difference

[0132] The measurements were performed using an Axoscan (manufactured by Axometrics). The measurement temperature was 23°C. Furthermore, Re(450) / Re(550) was used as an indicator of wavelength dispersion characteristics and calculated.

[0133] (5) Uneven hue

[0134] The circular polarizing plates with anti-reflective layers obtained through the examples and comparative examples were cut to specified dimensions and adhered to alkali-free glass plates using an acrylic adhesive layer to prepare test samples. These test samples were placed face-to-face in an organic EL device substitute, and hue unevenness (stripe unevenness) was visually observed under fluorescent light and evaluated according to the following criteria.

[0135] It should be noted that the OLED display device alternative is manufactured as follows: Metal wiring is printed on an acrylic sheet to achieve a specified reflectivity, thus serving as the OLED display device alternative. The metal wiring is printed to achieve a reflectivity of 21.88% or 40.34% for the OLED display device alternative.

[0136] A: In essence, no hue unevenness was detected.

[0137] B: Uneven hue has been identified, but it is within a practically acceptable range.

[0138] C: The uneven hue is obvious and unacceptable in practical use.

[0139] (6)b * value

[0140] The test sample, prepared in the same manner as in (5) above, was placed on an organic EL device substitute with the glass plates facing each other, and measured using a spectrophotometer "CM-2600d" manufactured by KONICA MINOLTA.

[0141] (7) Y value

[0142] The test sample, prepared in the same manner as in (5) above, was placed on an organic EL device substitute with the glass plates facing each other, and the determination was performed using a spectrophotometer "CM-2600d" manufactured by KONICA MINOLTA, using a method based on JIS Z 8722.

[0143] [Manufacturing Example 1: Fabrication of Polarizing Components]

[0144] A polyvinyl alcohol (PVA) film with an average degree of polymerization of 2400, a saponification degree of 99.9 mol%, and a thickness of 45 μm was immersed in warm water at 30°C for 60 seconds to allow it to swell. Next, it was immersed in a 0.3% aqueous solution of iodine / potassium iodide (weight ratio = 1 / 7) and stretched to 2.6 times while being dyed. Subsequently, it was stretched in a 4% boric acid aqueous solution at 65°C with a total stretch ratio of 6 times. After stretching, it was dried in an oven at 55°C for 1 minute to obtain a PVA-based polarizing element. This polarizing element had a thickness of 18 μm and a moisture content of 15% by weight.

[0145] [Manufacturing Example 2: Fabrication of the Phase Retardation Thin Film Constituting the Phase Retardation Layer]

[0146] [Manufacturing Example 2-1]

[0147] Relative to 81.98 parts by mass of isosorbide (hereinafter sometimes abbreviated as "ISB"), 47.19 parts by mass of tricyclodecanediethanol (hereinafter sometimes abbreviated as "TCDDM"), 175.1 parts by mass of diphenyl carbonate (hereinafter sometimes abbreviated as "DPC"), and 0.979 parts by mass of a 0.2% by mass aqueous solution of cesium carbonate as a catalyst were added to a reaction vessel. As the first stage of the reaction, under a nitrogen atmosphere, the temperature of the heating tank was raised to 150°C, and the raw materials were dissolved by stirring as needed (approximately 15 minutes). Next, the pressure was changed from atmospheric pressure to 13.3 kPa, and the temperature of the heating tank was raised to 190°C over 1 hour while the generated phenol was discharged from the reaction vessel. After maintaining the entire reaction vessel at 190°C for 15 minutes, as the second stage, the pressure inside the reaction vessel was set to 6.67 kPa, and the temperature of the heating tank was raised to 230°C over 15 minutes, during which the generated phenol was discharged from the reaction vessel. As the stirring torque of the mixer gradually increases, the temperature is raised to 250°C over 8 minutes. To remove the generated phenol, the pressure inside the reaction vessel is brought down to below 0.200 kPa. After reaching the specified stirring torque, the reaction is terminated, and the resulting reactants are extruded into water to obtain polycarbonate copolymer granules.

[0148] The obtained granules were vacuum dried at 80°C for 5 hours, and then a resin film was made using a film forming apparatus equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., barrel setting temperature: 250°C), a T-die (width: 200mm, setting temperature: 250°C), a cooling roller (setting temperature: 120~130°C), and a winding machine. The resulting elongated resin film was stretched to obtain a phase difference film. By changing the stretching conditions, phase difference films with Re(550) of 135nm, 140nm, or 144nm were obtained. The Re(450) / Re(550) ratio of any phase difference film was 1.02.

[0149] [Manufacturing Example 2-2]

[0150] A commercially available cyclic olefin resin film (manufactured by ZEON Corporation, Japan, product name "ZEONORE") was stretched to obtain a phase retardation film. By changing the stretching conditions, phase retardation films with Re(550) of 140 nm or 144 nm were obtained. The Re(450) / Re(550) ratio of any phase retardation film was 1.02.

[0151] [Manufacturing Example 3: Fabrication of an Anti-reflective Layer]

[0152] [Manufacturing Example 3-1: Preparation of Hard Coating]

[0153] As a resin included in the hard coating, 100 parts by weight of a UV-curable urethane acrylate resin (manufactured by DIC, trade name "UNIDIC 17-806", 80% solids content) was prepared. Relative to the 100 parts by weight of the aforementioned resin solids content, 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907") and 0.01 parts by weight of a leveling agent (manufactured by DIC, trade name "GRANDIC PC4100", 10% solids content) were mixed. This mixture was diluted with a butyl acetate / cyclopentanone mixed solvent (weight ratio 80 / 20) to a solids content concentration of 40% to prepare a hard coating forming material (coating liquid). The coating liquid was applied to the surface of a substrate (a 60 μm thick TAC film) using a wire rod. The coated coating liquid was heated at 80°C for 1 minute to dry and form a coating film. The dried coating film was irradiated with a high-pressure mercury lamp, accumulating a light intensity of 300 mJ / cm². 2 The substrate is cured by ultraviolet light to obtain a hard coating film (hard coating layer).

[0154] [Manufacturing Example 3-2: Fabrication of an Anti-reflective Layer]

[0155] The following ingredients were prepared: 100 parts by weight of a multifunctional acrylate with pentaerythritol triacrylate as the main component (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #300", solid content 100% by weight); 100 parts by weight of hollow nano-silica particles (manufactured by Nichibukai Chemical Industry Co., Ltd., trade name "THRULYA 5320", solid content 20% by weight, weight average particle size 75nm); 40 parts by weight of solid nano-silica particles (manufactured by Nissan Chemical Industry Co., Ltd., trade name "MEK-2140Z-AC", solid content 30% by weight, weight average particle size 10nm); 12 parts by weight of an additive containing fluorine (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KY-1203", solid content 20% by weight); and a photopolymerization initiator (IGM Resins). Three parts by weight of a product manufactured by BV (trade name "Omnirad 907", solid content 100% by weight) were mixed. A mixed solvent, obtained by mixing TBA (tert-butanol), MIBK (methyl isobutyl ketone), and PMA (propylene glycol monomethyl ether acetate) in a weight ratio of 60:25:15, was added to this mixture as a diluent, bringing the total solid content to 4% by weight. The mixture was stirred to prepare a coating liquid for forming an antireflective layer.

[0156] The antireflective coating solution was applied to the surface of the hard coating layer of the substrate / hard coating laminate obtained in Example 3-1 using a wire rod. The applied coating solution was heated at 80°C for 1 minute to dry and form a coating film. The dried coating film was irradiated with a high-pressure mercury lamp, and the cumulative light intensity was 300 mJ / cm². 2 The material is subjected to ultraviolet light for curing, forming an anti-reflective layer with a refractive index of 1.36. This process is repeated to create a laminate of substrate / hard coating (HC) layer / anti-reflective layer.

[0157] Furthermore, by changing the mixing ratio of hollow nano-silica particles, an antireflective layer with a refractive index of 1.34 or 1.30 is formed. Furthermore, by changing the coating thickness of the coating liquid, the thickness of the formed antireflective layer is changed. An antireflective layer with the refractive index and thickness shown in Table 1 below is formed.

[0158] [Manufacturing Example 4: Preparation of Active Energy Ray Curable Adhesive]

[0159] The following mixtures were prepared: 12 parts by weight of free radical polymerizable compound (a), 35 parts by weight of free radical polymerizable compound (b), 40 parts by weight of free radical polymerizable compound (c), 10 parts by weight of oligomer compound (d), 2 parts by weight of photopolymerization initiator (e), and 1 part by weight of photosensitizer (f). The mixture was stirred at 50°C for 1 hour to obtain an active energy radiation-cured adhesive. It should be noted that the free radical polymerizable compound (a) is HEAA (hydroxyethyl acrylamide) (manufactured by KJ Chemicals); the free radical polymerizable compound (b) is ACMO (acryloylmorpholine) (manufactured by KJ Chemicals); the free radical polymerizable compound (c) is Light Acrylate 1,9ND-A (1,9-nonanediol diacrylate) (manufactured by Kyoeisha Chemical Co., Ltd.); the oligomer compound (d) is ARUFON UG-4010 (epoxy-modified acrylic oligomer) (manufactured by Toa Synthetic Co., Ltd.); the photopolymerization initiator (e) is Omnirad907 (2-methyl-1-(4-methylthiophene)-2-morpholinopropane-1-one) (manufactured by IGMresins BV); and the photosensitizer (f) is KAYACURE DETX-S (2,4-diethylthioxanone) (manufactured by Nippon Kayaku Co., Ltd.).

[0160] [Example 1]

[0161] Using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd.) (unit shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed: 140% / relative to linear speed), the active energy radiation-curable adhesive obtained in Manufacturing Example 4 was coated to a thickness of 0.7 μm onto the surface of the substrate of the laminate obtained in Manufacturing Example 3 and one surface of the phase retardation film obtained in Manufacturing Example 2-1, respectively. The adhesive was then bonded to both sides of the polarizer obtained in Manufacturing Example 1 using a roller-to-roll method. Next, the active energy radiation-curable adhesive was cured by irradiating visible light from both sides using an active energy radiation irradiation device. After curing, it was dried with hot air at 70°C for 3 minutes to produce a circular polarizer with an anti-reflective layer, consisting of an anti-reflective layer / HC layer / substrate / polarizer / phase retardation layer. It should be noted that an acrylic adhesive layer (23 μm) is provided on the surface of the phase retardation layer of the circular polarizer with the anti-reflective layer (on the side opposite to the polarizer). The resulting circular polarizing plate with an anti-reflective layer was placed on an organic EL display device alternative having the reflectivity shown in Table 1 and evaluated in (5) to (7) above. The results are shown in Table 1.

[0162] [Examples 2-6 and Comparative Examples 1-7]

[0163] Except that the anti-reflective layer and the phase détramorphic layer are configured as shown in Table 1, the same procedure as in Example 1 is followed to obtain a circular polarizer with an anti-reflective layer. The obtained circular polarizer with an anti-reflective layer is placed on an organic EL display device alternative having the reflectivity shown in Table 1 and evaluated in (5) to (7) above. The results are shown in Table 1.

[0164] [Table 1]

[0165]

[0166] [evaluate]

[0167] Table 1 clearly shows that the hue unevenness and b of the circular polarizer with anti-reflective layer in the embodiments of the present invention are... * Both the chromaticity and Y value are excellent. If either the bottom wavelength or thickness of the antireflective layer, or the Re(550) of the phase retardation layer, deviates from the range of the embodiments of the present invention, hue inhomogeneity and b will occur. * At least one of the chromatic aberration value and the Y value is insufficient. Thus, it can be seen that the circular polarizer with an anti-reflective layer in the embodiments of the present invention can achieve an image display device in which hue unevenness is suppressed. Furthermore, it can be seen that this effect can be obtained in an image display device with low reflectivity.

[0168] Industrial availability

[0169] The circular polarizer with an anti-reflective layer of the present invention can be suitably used in image display devices (such as liquid crystal display devices and organic EL display devices).

Claims

1. A circular polarizer with an anti-reflective layer, comprising: a polarizer, an anti-reflective layer disposed on one side of the polarizer, and a phase retardation layer disposed on the other side of the polarizer. The antireflective layer has a refractive index of 1.29–1.38 and a thickness of 70 nm–120 nm. Furthermore, within the wavelength range of 380 nm–780 nm, the wavelength range of 400 nm–600 nm provides the lowest reflectivity. The Re(550) of this phase difference layer is 136 nm to 200 nm. The angle between the slow axis of the phase difference layer and the absorption axis of the polarizer is 40° to 50° or 130° to 140°.

2. The circular polarizing plate with an anti-reflective layer according to claim 1, wherein, The reflectivity of the anti-reflective layer is less than 1.5%.

3. The circular polarizing plate with an anti-reflective layer according to claim 1 or 2, wherein, The phase retardation layer is composed of a stretched film of resin film, with Re(450) / Re(550) ranging from 0.97 to 1.

03. Here, Re(450) and Re(550) are the in-plane phase differences measured at 23°C using light with wavelengths of 450 nm and 550 nm, respectively.

4. An image display device, comprising, on the visual recognition side, a circular polarizing plate with an anti-reflective layer as described in any one of claims 1 to 3. The anti-reflective layer of the circular polarizing plate is disposed on the visual recognition side. The reflectivity of the image display device is less than 40%.

5. The image display device according to claim 4, wherein it is an organic electroluminescent display device.

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