JP2021173831A - Circularly polarizing plate with anti-reflection layer and image display device using the same - Google Patents

Abstract

To provide a circularly polarizing plate with an anti-reflection layer, which allows for producing an image display device that offers suppressed hue unevenness.SOLUTION: A circularly polarizing plate with an anti-reflection layer according to the present invention comprises a polarizer, an anti-reflection layer provided on one side of the polarizer, and a retardation layer provided on the other side of the polarizer. The anti-reflection layer has a refractive index in a range of 1.29-1.38, a thickness in a range of 70-120 nm, and a minimum reflectance wavelength in a range of 400-600 nm for a 380-780 nm range. The retardation layer has Re(550) in a range of 136-200 nm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a circularly polarizing plate with an antireflection layer and an image display device using the circularly polarizing plate with an antireflection layer.

In recent years, image display devices represented by liquid crystal displays and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have rapidly become widespread. In the image display device, a circular polarizing plate including a polarizing plate and a retardation plate may be used. However, when the circularly polarizing plate is applied to an image display device having a low reflectance (particularly, an organic EL display device), there is a problem that hue unevenness is easily visually recognized.

Patent No. 5876441 Japanese Unexamined Patent Publication No. 2014-0262666

The present invention has been made to solve the above-mentioned conventional problems, and a main object thereof is to provide a circularly polarizing plate with an antireflection layer capable of realizing an image display device in which hue unevenness is suppressed.

The circularly polarizing plate with an antireflection layer according to the embodiment of the present invention includes a polarizing element, an antireflection layer arranged on one side of the polarizer, and a retardation layer arranged on the other side of the polarizer. And have. The antireflection layer has a refractive index of 1.29 to 1.38, a thickness of 70 nm to 120 nm, and a wavelength in the wavelength range of 380 nm to 780 nm at which the lowest reflectance is obtained in the wavelength range of 400 nm to 600 nm. Exists in. The Re (550) of the retardation layer is 136 nm to 200 nm.
In one embodiment, the antireflection layer has a reflectance of 1.5% or less.
In one embodiment, the angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is 40 ° to 50 ° or 130 ° to 140 °.
In one embodiment, the retardation layer is composed of a stretched film of a resin film, and Re (450) / Re (550) is 0.97 to 1.03. Here, Re (450) and Re (550) are in-plane phase differences measured with light having wavelengths of 450 nm and 550 nm at 23 ° C., respectively.
According to another aspect of the present invention, an image display device is provided. This image display device includes the above-mentioned circularly polarizing plate with an antireflection layer on the viewing side. The circularly polarizing plate with an antireflection layer is arranged so that the antireflection layer is on the viewing side. The reflectance of the image display device is 40% or less.
In one embodiment, the image display device is an organic electroluminescence display device.

According to the embodiment of the present invention, in the circular polarizing plate, an antireflection layer is provided on the side that becomes a visible side when applied to an image display device, and the refractive index, thickness, and visible light region of the antireflection layer are provided. A circular polarizing plate with an antireflection layer that can realize an image display device in which hue unevenness is suppressed by optimizing the in-plane phase difference of the retardation layer by combining and optimizing the wavelengths at which the minimum reflectance can be obtained. Can be obtained. Further, the circularly polarizing plate with an antireflection layer can realize high transmittance in addition to the above effects.

It is schematic cross-sectional view of the circularly polarizing plate with an antireflection layer according to one Embodiment of this invention.

Hereinafter, typical embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and “ny” is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, 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 having a wavelength of λ nm at 23 ° C. For example, "Re (450)" is an in-plane phase difference of a film measured with light having a wavelength of 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 a phase difference in the thickness direction of the film measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (450)" is a phase difference in the thickness direction of a film measured with light having a wavelength of 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 the present specification, the angle includes an angle in both clockwise and counterclockwise directions unless otherwise specified.

A. Overall Configuration of Circularly Polarized Plate with Antireflection Layer FIG. 1 is a schematic cross-sectional view of a circularly polarizing plate with an antireflection layer according to one embodiment of the present invention. The circularly polarizing plate 100 with an antireflection layer in the illustrated example is arranged on one side of the polarizing plate 10 and the polarizing plate 10 (for example, the side opposite to the image display cell when applied to an image display device, that is, the visual recognition side). The antireflection layer 30 is provided, and the retardation layer 40 is arranged on the other side of the polarizing plate 10 (for example, the image display cell side when applied to an image display device). The antireflection layer 30 and the retardation layer 40 are attached to the polarizing plate 10 via any suitable adhesive layer or adhesive layer (not shown), respectively. The polarizing plate 10 is provided on the polarizing element 11, the first protective layer 12 arranged on one side of the polarizing element 11 (antireflection layer side), and on the other side (phase difference layer side) of the polarizing element 11. Includes a second protective layer 13 arranged. Depending on the purpose, one or both of the first protective layer 12 and the second protective layer 13 may be omitted. For example, since the retardation layer 30 can also function as a protective layer for the polarizer 11, the second protective layer 13 may be omitted. Further, for example, when the antireflection layer is typically formed on a base material as described later, the laminate of the base material / antireflection layer may function as a protective layer. In this case, the first protective layer 12 may be omitted. The base material / antireflection layer laminate may further include a hard coat layer. Therefore, in the polarizing plate with a reflective layer, both protective layers are omitted, and the polarizing element 11, the antireflection layer 30 arranged on one side of the polarizer 11, and the polarizing element 11 are arranged on the other side. It may be configured to include the retarded retardation layer 40 (such a configuration includes a configuration in which one or both of the polarizers include a protective layer). Practically, an arbitrary appropriate adhesive layer 50 is provided on the opposite side of the retardation layer 40 from the polarizing plate 10 as an outermost layer, and the circularly polarizing plate with an antireflection layer can be attached to an image display cell. ing.

In embodiments of the present invention, the antireflection layer has a refractive index of 1.29 to 1.38, a thickness of 70 nm to 120 nm, and a wavelength at which the lowest reflectance is obtained in the wavelength range of 380 nm to 780 nm. (Hereinafter, it may be referred to as a bottom wavelength) exists in the range of 400 nm to 600 nm. By optimizing the combination of the refractive index, the thickness, and the bottom wavelength of the antireflection layer in this way, it is possible to realize an image display device in which hue unevenness is suppressed. Details of the antireflection layer will be described later in Section E.

The retardation layer 40 is typically composed of a stretched film of a resin film. The Re (550) of the retardation layer 40 is typically 136 nm to 200 nm. The Re (450) / Re (550) of the retardation layer is preferably 0.97 to 1.03. The angle formed by 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 °, and even more preferably 44 ° to 46 °. Yes, particularly preferably about 45 °; or preferably 130 ° to 140 °, more preferably 132 ° to 138 °, still more preferably 134 ° to 136 °, particularly preferably about 135 °. °.

In one embodiment, the antireflection layered circularly polarizing plate may further have another retardation layer (not shown) between the retardation layer 40 and the pressure-sensitive adhesive layer 50. Another retardation layer typically exhibits a relationship in which the refractive index characteristic is nz> nz = ny. By providing such another retardation layer, it is possible to satisfactorily prevent reflection in the oblique direction, and it is possible to widen the viewing angle of the antireflection function.

In one embodiment, the anti-reflection layered circularly polarizing plate may further have a conductive layer or an isotropic substrate with a conductive layer (not shown). When an isotropic base material with a conductive layer or a conductive layer is provided, the circularly polarizing plate with an antireflection layer is a so-called inner touch panel in which a touch sensor is incorporated between an image display cell (for example, an organic EL cell) and the polarizing plate. It can be applied to type input display devices. The conductive layer or the isotropic base material with the conductive layer is typically provided between the retardation layer 40 and the pressure-sensitive adhesive layer 50. When another retardation layer is provided, the other retardation layer and the conductive layer or the isotropic base material with the conductive layer are typically provided in this order from the retardation layer 40 side.

The circularly polarizing plate with an antireflection layer may have an additional retardation layer (not shown). The additional retardation layer may be provided in combination with another retardation layer, or may be provided alone (ie, without providing another retardation layer). The optical characteristics (for example, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of the further retardation layer can be appropriately set according to the purpose.

The circularly polarizing plate with an antireflection layer may be single-wafered or elongated. As used herein, the term "long" means an elongated shape having a length sufficiently long with respect to the width, and for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width. include. The elongated circularly polarizing plate with an antireflection layer can be wound in a roll shape.

Practically, it is preferable that a release film is temporarily attached to the surface of the pressure-sensitive adhesive layer 50 until a circularly polarizing plate with an antireflection layer is used. By temporarily attaching the release film, the pressure-sensitive adhesive layer can be protected and a roll of a circularly polarizing plate with an antireflection layer can be formed.

Hereinafter, the components of the circularly polarizing plate with the antireflection layer will be described.

B. Polarizer As the polarizer 11, any suitable polarizer can be adopted. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is used.

The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, it may be stretched and then dyed. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt and blocking inhibitor on the surface of the PVA-based film, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. The polarizer obtained by using the laminate of the resin base material and the PVA-based resin layer coated and formed on the resin base material is, for example, a resin base material obtained by applying a PVA-based resin solution to the resin base material and drying the resin base material. It is produced by forming a PVA-based resin layer on the PVA-based resin layer to obtain a laminate of a resin base material and a PVA-based resin layer; stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Further, stretching may further include, if necessary, stretching the laminate in the air at a high temperature (eg, 95 ° C. or higher) prior to stretching in boric acid aqueous solution. The obtained resin substrate / polarizer laminate may be used as it is (that is, the resin substrate may be used as a protective layer for the polarizer), and the resin substrate is peeled off from the resin substrate / polarizer laminate. Then, an arbitrary appropriate protective layer according to the purpose may be laminated on the peeled surface. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The description of these patent documents is incorporated herein by reference.

The polarizer may preferably be composed of a single layer resin film. With such a configuration, a circularly polarizing plate with an antireflection layer in which phase difference unevenness is suppressed in a high temperature environment due to a synergistic effect with optimization of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer can be obtained. Can be obtained.

The thickness of the polarizer is preferably about 1 μm to 30 μm, more preferably about 5 μm to 25 μm. In particular, in order to obtain a polarizer having a thickness of 10 μm or less, a film is formed on a thermoplastic resin substrate as the polyvinyl alcohol-based film disclosed in JP2012-73580A, Patent No. 6470455, etc. A method for producing a thin polarizer using a laminate containing a polyvinyl alcohol-based film can be applied. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance 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 further preferably 99.9% or more.

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 the polarizer. Specific examples of the material that is the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based. , Polyester-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, acetate-based transparent resins and the like. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, 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, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

As will be described later, the circularly polarizing plate with the antireflection layer is typically arranged on the visual side of the image display device, and the first protective layer 12 is typically arranged on the visual side. Therefore, the first protective layer 12 may be subjected to surface treatment such as hard coat treatment, antireflection treatment, anti-sticking treatment, and anti-glare treatment, if necessary. Further / or, if necessary, the first protective layer 12 is provided with a process for improving visibility when visually recognizing through polarized sunglasses (typically, a (elliptical) circularly polarized light function is imparted. (Giving an ultra-high phase difference) may be applied. By performing such processing, excellent visibility can be realized even when the display screen is visually recognized through a polarized lens such as polarized sunglasses. Therefore, the circularly polarizing plate with an antireflection layer can be suitably applied to an image display device that can be used outdoors.

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 the surface treatment is applied, the thickness of the outer protective layer is the thickness including the thickness of the surface treatment layer.

The second protective layer 13 is preferably optically isotropic in one embodiment. As used herein, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is -10 nm to +10 nm. say.

D. In-plane retardation Re (550) of the retardation layer is typically 136 nm to 200 nm, preferably 136 nm to 180 nm, more preferably 136 nm to 160 nm, and even more preferably 136 nm to 200 nm as described above. It is 136 nm to 150 nm. That is, the retardation layer can function as a so-called λ / 4 plate. Further, when the Re (550) of the retardation layer is 136 nm or more, it is possible to realize an image display device having a very excellent reflection hue and a small visual reflectance (Y value).

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

Since the retardation layer has an in-plane retardation as described above, it has a relationship of nx> ny. The retardation layer exhibits any suitable refractive index characteristic as long as it has a relationship of nx> ny. The refractive index characteristics of the retardation layer typically show a relationship of nx> ny ≧ nz. Here, "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effect of the present invention is not impaired. The Nz coefficient of the retardation layer is preferably 0.9 to 2.0, more preferably 0.9 to 1.5, and even more preferably 0.9 to 1.2. By satisfying such a relationship, when a circularly polarizing plate with an antireflection layer is used in an image display device, a very excellent reflection hue can be achieved.

The thickness of the retardation layer can be set to best function as a λ / 4 plate. In other words, the thickness can be set to obtain the desired in-plane phase difference. Specifically, the thickness is preferably 70 μm or less, preferably 45 μm to 60 μm. When the thickness of the retardation layer is within such a range, it is possible to satisfactorily adjust the curl at the time of bonding while satisfactorily suppressing the curl at the time of heating.

The absolute value of the photoelastic coefficient of the retardation layer is preferably 20 × 10 ^-12 (m ² / N) or less, and more preferably 1.0 × 10 ^-12 (m ² / N) to 15 × 10. ^{It is -12} (m ² / N), more preferably 2.0 × 10 ^-12 (m ² / N) to 12 × 10 ^-12 (m ² / N). When the absolute value of the photoelastic coefficient is in such a range, display unevenness can be suppressed when the circularly polarizing plate with an antireflection layer is applied to an image display device.

The retardation layer may be composed of any suitable resin film that can satisfy the above characteristics. Typical examples of such resins are polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, and polyamide resins. , Polyethylene resin, polyether resin, polystyrene resin, acrylic resin and the like. These resins may be used alone or in combination (eg, blending, copolymerizing). The retardation layer may be typically composed of a cyclic olefin resin, a polycarbonate resin, or a polyester carbonate resin (hereinafter, may be simply referred to as a polycarbonate resin).

A typical example of the cyclic olefin resin is a norbornene resin. The norbornene-based resin is a resin that is polymerized using a norbornene-based monomer as a polymerization unit. Examples of the norbornene-based monomer include norbornene and its alkyl and / or alkylidene substituents, for example, 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl. Polar group substituents such as these halogens such as -2-norbornene, 5-ethylidene-2-norbornene; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene. Substitutes and polar group substituents such as halogen, such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4 4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-Cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1, 4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1, 4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octa Hydronaphthalene, etc .; 3-4 weights of cyclopentadiene, eg, 4,9: 5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoinden, 4, Examples thereof include 11: 5, 10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentadianthracene and the like. The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.

As the polymerization unit in the norbornene-based resin, other cycloolefins capable of ring-opening polymerization can be used in combination. Specific examples of such cycloolefins include compounds having one reactive double bond, such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

The cyclic olefin resin preferably has a number average molecular weight (Mn) of 25,000 to 200,000, more preferably 30,000 to 100, measured by a gel permeation chromatography (GPC) method using a toluene solvent. 000, most preferably 40,000 to 80,000. When the number average molecular weight is in the above range, it is possible to obtain a product having excellent mechanical strength, good solubility, moldability, and operability of casting.

A commercially available film may be used as the cyclic olefin resin film. Specific examples include Zeon Corporation's product names "Zeonex" and "Zeonoa", JSR's product name "Arton", TICONA's product name "Topus", and Mitsui Chemicals' product name. "APEL" can be mentioned.

The polycarbonate-based resin typically contains a structural unit derived from a dihydroxy compound having a bonding structure represented by the following formula (I).

Examples of the dihydroxy compound include a compound represented by the following formula (II). Examples of such dihydroxy compounds include isosorbide, isomannide, and isoidet, which are in a stereoisomeric relationship. These may be used alone or in combination of two or more.

The above dihydroxy compound and another dihydroxy compound may be used in combination. As another dihydroxy compound, for example, an alicyclic dihydroxy compound represented by the following formula (III) can be mentioned.
HOCH _2- R ^1- CH ₂ OH ... (III)
In formula (III), R ¹ represents a cycloalkylene group having 4 to 20 carbon atoms. The alicyclic dihydroxy compound can be, for example, tricyclodecanedimethanol, pentacyclopentadecanedimethanol. These include ^{R 1} in formula (III) is the following formula (IV) (wherein, n represents 0 or 1) the various isomers represented by.

In one embodiment, the polycarbonate resin contains a structural unit represented by the following formula (V). That is, the polycarbonate resin can be a copolymer of diphenyl carbonate, isosorbide, and tricyclodecanedimethanol.

Details of such a polycarbonate resin are described in, for example, Japanese Patent Application Laid-Open No. 2012-031370, and the description of the publication is incorporated herein by reference.

The glass transition temperature of the polycarbonate resin is preferably 110 ° C. or higher and 250 ° C. or lower, and more preferably 120 ° C. or higher and 230 ° C. or lower. If the glass transition temperature is excessively low, the heat resistance tends to deteriorate, which may cause a dimensional change after film molding. If the glass transition temperature is excessively high, the molding stability during film molding may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature is determined according to JIS K 7121 (1987).

The molecular weight of the polycarbonate resin can be expressed by the reduced viscosity. The reduced viscosity is measured by using methylene chloride as a solvent, precisely adjusting the resin concentration to 0.6 g / dL, and using an Ubbelohde viscous tube at a temperature of 20.0 ° C. ± 0.1 ° C. The lower limit of the reduction viscosity is usually preferably 0.30 dL / g, more preferably 0.35 dL / g or more. The upper limit of the reduction viscosity is usually preferably 1.20 dL / g, more preferably 1.00 dL / g, and further preferably 0.80 dL / g. If the reduced viscosity is smaller than the lower limit, there may be a problem that the mechanical strength of the molded product is reduced. On the other hand, if the reduced viscosity is larger than the upper limit value, the fluidity at the time of molding is lowered, and there may be a problem that the productivity and the moldability are lowered.

A commercially available film may be used as the polycarbonate resin film. Specific examples of commercially available products include the product names "Pure Ace WR-S", "Pure Ace WR-W", "Pure Ace WR-M" manufactured by Teijin Limited, and the product name "NRF" manufactured by Nitto Denko. Be done.

The retardation layer can be obtained, for example, by stretching a film formed of the above resin. As a method for forming the resin film, any suitable molding processing method can be adopted. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (for example, a casting method), a calendar molding method, and a hot press. Law etc. can be mentioned. Extrusion molding method or cast coating method is preferable. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the retardation layer, and the like. As described above, since many resin film products are commercially available, the commercially available film may be subjected to the stretching treatment as it is.

The thickness of the resin film (unstretched film) can be set to an arbitrary appropriate value according to a desired thickness of the retardation layer, desired optical characteristics, stretching conditions described later, and the like. It is preferably 50 μm to 300 μm.

Any suitable stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching direction) can be adopted for the stretching. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, and fixed-end contraction can be used alone or simultaneously or sequentially. As for the stretching direction, it can be performed in various directions and dimensions such as a length direction, a width direction, a thickness direction, and an oblique direction. The stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C, relative to the glass transition temperature (Tg) of the resin film.

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

In one embodiment, the retardation film is made by uniaxially stretching or fixed end uniaxially stretching the resin film. Specific examples of the fixed-end uniaxial stretching include a method of stretching the resin film in the width direction (lateral direction) while running the resin film in the longitudinal direction. The draw ratio is preferably 1.1 times to 3.5 times.

In another embodiment, the retardation film can be made by continuously obliquely stretching a long resin film in the direction of the above angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of an angle θ with respect to the longitudinal direction of the film (a slow axis in the direction of the angle θ) can be obtained. Roll-to-roll is possible, and the manufacturing process can be simplified. The angle θ may be an angle formed by the absorption axis of the polarizing film and the slow axis of the retardation layer in the polarizing plate with a retardation layer. As described above, the angle θ is preferably 40 ° to 50 °, more preferably 42 ° to 48 °, and even more preferably about 45 °.

Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force, a pulling force, or a pulling force at different speeds in the horizontal and / or vertical directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as the long resin film can be continuously and diagonally stretched.

By appropriately controlling the left and right velocities in the stretching machine, a retardation layer having the desired in-plane phase difference and having a slow phase axis in the desired direction (substantially long). (Phase difference film) can be obtained.

The stretching temperature of the film can change depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably Tg-30 ° C to Tg + 30 ° C, more preferably Tg-15 ° C to Tg + 20 ° C, and most preferably Tg-10 ° C to Tg + 15 ° C. By stretching at such a temperature, a retardation layer having appropriate characteristics in the present invention can be obtained. Tg is the glass transition temperature of the constituent material of the film.

E. Antireflection layer The antireflection layer 30 is typically a cured layer of an ionizing radiation curable resin composition. By providing the antireflection layer, it is possible to realize a high transmittance which is difficult to realize by the circularly polarizing plate alone.

The refractive index of the antireflection layer is 1.29 to 1.38 as described above, preferably 1.30 to 1.37, and more preferably 1.30 to 1.36. If the refractive index of the antireflection layer is within such a range, an image display device in which hue unevenness is suppressed can be realized by optimizing the combination of the thickness and the bottom wavelength.

The thickness of the antireflection layer is 70 nm to 120 nm, preferably 75 nm to 110 nm, and more preferably 75 nm to 100 nm as described above. When the thickness of the antireflection layer is within such a range, an image display device in which hue unevenness is suppressed can be realized by optimizing the combination of the refractive index and the bottom wavelength. If the thickness of the antireflection layer is too large, the reflected hue becomes too blue and / or the visual reflectance (Y value) becomes too large when the circularly polarizing plate with the antireflection layer is applied to an image display device. In some cases.

The antireflection layer has a bottom wavelength in the range of 400 nm to 600 nm, preferably in the range of 410 nm to 580 nm, and more preferably in the range of 420 nm to 550 nm as described above. If the bottom wavelength of the antireflection layer is within such a range, it is possible to realize an image display device in which hue unevenness is suppressed by optimizing the combination of thickness and refractive index. If the bottom wavelength is out of range, the reflected hue may become too blue and / or the visual reflectance (Y value) may become too large when the circularly polarizing plate with an antireflection layer is applied to an image display device. be.

The reflectance of the antireflection layer at the bottom wavelength is preferably 1.5% or less, more preferably 1.3% or less, still more preferably 1.0% or less. The smaller the reflectance, the more preferable, and the lower limit thereof can be, for example, 0.2%. When the reflectance is in such a range, it is possible to prevent reflection of external light and the like.

The ionizing radiation curable resin composition contains an ionizing radiation curable resin. The ionizing radiation curable resin composition may further contain a reactive diluent, a fluorine element-containing additive, hollow particles, and / or solid particles, depending on the purpose.

Typical examples of the ionizing radiation curable resin include a thermosetting resin, an ultraviolet curable resin, a light (visible light) curable resin, and an electron beam curable resin. For example, examples of the ionizing radiation curable resin include silicone resin, polyester resin, polyether resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, and polythiol polyene resin. Further, for example, the ionizing radiation curable resin can be a curable compound having an acrylate group and / or a methacrylate group that is cured by heat, light (ultraviolet rays, etc.), an electron beam, or the like. Specific examples include oligomers or prepolymers such as acrylates and / or methacrylates of polyfunctional compounds such as polyhydric alcohols. The ionizing radiation curable resin may be used alone or in combination of two or more.

The ionizing radiation curable resin may have a weight average molecular weight before curing, for example, 100 or more, 300 or more, 500 or more, 1000 or more, or 2000 or more, and 100,000 or less, 70,000 or less, 50,000 or less, 30,000 or less, Alternatively, it may be 10,000 or less. If the weight average molecular weight before curing is large, the hardness tends to decrease, but cracks tend to be less likely to occur when bent. If the weight average molecular weight before curing is small, the intermolecular crosslink density tends to be improved and the hardness tends to be high.

Reactive diluents typically include an acrylate group and / or a methacrylate group. As the reactive diluent, for example, the reactive diluent described in JP-A-2008-88309 can be used. Specific examples of the reactive diluent include monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, and polyfunctional methacrylate. Preferably, it is a trifunctional or higher functional acrylate or a trifunctional or higher functional methacrylate. Examples of the reactive diluent include butanediol glycerin ether diacrylate, isocyanuric acid acrylate, and isocyanuric acid methacrylate. The reactive diluent may be used alone or in combination of two or more.

Any suitable compound can be used as the fluorine element-containing additive. The fluorine element-containing additive can be, for example, an organic compound or an inorganic compound containing fluorine in the molecule. Examples of the organic compound include a fluorine-containing antifouling coating agent, a fluorine-containing acrylic compound, and a fluorine / silicon-containing acrylic compound. As the organic compound, a commercially available product may be used. Specific examples include the product name "KY-1203" manufactured by Shin-Etsu Chemical Co., Ltd. and the product name "Mega Fuck" manufactured by DIC Corporation. As the inorganic compound, any suitable fluorine-containing inorganic compound can be used.

The blending amount of the fluorine element-containing additive is, for example, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, 0.20 parts by weight with respect to 100 parts by weight of the ionizing radiation curable resin. It may be more than or equal to 0.25 parts by weight or more, and may be 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less.

As the hollow particles, any suitable hollow particles can be used. Specific examples include silica particles, acrylic particles, and acrylic-styrene copolymer particles. Commercially available products may be used as the hollow particles. Specific examples of commercially available silica particles include the trade names "Thruria 5320" and "Thruria 4320" manufactured by JGC Catalysts and Chemicals Co., Ltd. The weight average particle size of the hollow particles may be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, and is 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. May be good. Any suitable shape can be adopted as the shape of the hollow particles. The shape of the hollow particles may be, for example, a bead-shaped substantially spherical shape, or an irregular shape such as powder. It is preferably substantially spherical, more preferably substantially spherical with an aspect ratio of 1.5 or less, and even more preferably substantially true spherical. By blending the hollow particles, an antireflection layer having a low refractive index and good antireflection characteristics can be obtained. The amount of the hollow particles to be blended may 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 more with respect to 100 parts by weight of the ionizing radiation curable resin. It may be 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, 200 parts by weight or less, or 180 parts by weight or less. When the blending amount is in such a range, an antireflection layer having excellent mechanical properties and a low refractive index can be obtained.

As the solid particles, any suitable solid particles can be used. Specific examples include silica particles, zirconium oxide particles, and titanium particles. Commercially available products may be used as the solid particles. Specific examples of commercially available silica particles include trade names "MEK-2140Z-AC", "MIBK-ST", and "IPA-ST" manufactured by Nissan Chemical Industries, Ltd. The weight average particle size of the solid particles may be, for example, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, or 25 nm or more, and is 3300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. You may. Any suitable shape can be adopted as the shape of the solid particles. The shape of the solid particles may be, for example, a bead-shaped substantially spherical shape, or an amorphous shape such as powder. It is preferably substantially spherical, more preferably substantially spherical with an aspect ratio of 1.5 or less, and even more preferably substantially true spherical. By blending the solid particles, the fluorine element-containing additive tends to be unevenly distributed on the surface of the antireflection layer, and as a result, an antireflection layer having a low refractive index and good antireflection characteristics can be obtained. The blending amount of the solid particles is, 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 with respect to 100 parts by weight of the ionizing radiation curable resin. It may be 150 parts by weight or less, 120 parts by weight or less, 100 parts by weight or less, 100 parts by weight or less, or 80 parts by weight or less. When the blending amount is in such a range, an antireflection layer having an excellent balance of mechanical properties, refractive index and transparency can be obtained.

The antireflection layer can be typically formed by the following manufacturing method: a coating solution for forming an antireflection layer obtained by diluting an ionizing radiation curable resin composition with a diluting solvent is applied; and the coating film is dried. And cure the dry coating film.

As the diluting solvent, any suitable solvent can be used depending on the ionizing radiation curable resin. Examples of the diluting solvent include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, TBA (terrary butyl alcohol) and 2-methoxyethanol; and ketones such as acetone, methyl ethyl ketone, MIBK (methyl isobutyl ketone) and cyclopentanone. Classes; esters such as methyl acetate, ethyl acetate, butyl acetate, PMA (propylene glycol monomethyl ether acetate); ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; ethyl cellosolve, butyl cellosolve Such as cellosolves; aliphatic hydrocarbons such as hexane, heptane and octane; aromatic hydrocarbons such as benzene, toluene and xylene. The diluting solvent may be used alone or in combination of two or more. The polarity can be adjusted by mixing a plurality of solvents at an arbitrary appropriate ratio according to the purpose.

The diluting solvent can be, for example, a mixed solvent containing MIBK and PMA. The mixing ratio in this case can be appropriately set according to the purpose. The mixing ratio may 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 more, and 400 parts by weight or more, with respect to 100 parts by weight of MIBK. Hereinafter, it may be 350 parts by weight or less, 300 parts by weight or less, or 250 parts by weight or less.

The diluting solvent can be, for example, a mixed solvent containing TBA in addition to MIBK and PMA. The mixing ratio in this case can also be appropriately set according to the purpose. The mixing ratio may 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, and 200 parts by weight or more, with respect to 100 parts by weight of MIBK. Hereinafter, it may be 180 parts by weight or less, 150 parts by weight or less, 130 parts by weight or less, or 110 parts by weight or less; the TBA is, for example, 10 parts by weight or more, 30 parts by weight or more, 50 parts by weight or more, 80 parts by weight. It may be 2 parts or more, 100 parts by weight or more, 200 parts by weight or less, 180 parts by weight or less, 150 parts by weight or less, 130 parts by weight or less, or 110 parts by weight or less.

The solid content concentration of the coating liquid should be, 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 more. It may be 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. When the solid content concentration is within such a range, it is possible to achieve both coatability (for example, wetness and leveling) and prevention of poor appearance of the coating film (for example, air-drying unevenness and whitening).

A curing agent may be added to the coating liquid, if necessary. As the curing agent, any suitable polymerization initiator (for example, thermal polymerization initiator, photopolymerization initiator, etc.) can be used. The amount of the curing agent added is, for example, 0.5 parts by weight or more, 1.0 part by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or more than 100 parts by weight of the ionizing radiation curable resin. It may be 2.5 parts by weight or more, 15 parts by weight or less, 13 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less.

The antireflection layer is typically formed on any suitable substrate and then laminated onto a polarizer or polarizing plate via any suitable adhesive layer or pressure-sensitive adhesive layer. First, the coating liquid is applied onto the base material. As the coating method, any suitable method can be adopted. Specific examples include a fanten coating method, a die coating method, a spin coating method, a spray coating method, a gravure coating method, a roll coating method, and a bar coating method. The amount of the coating liquid applied can be appropriately set according to the thickness of the antireflection layer to be formed. The thickness of the antireflection layer formed may 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, and may be 50 μm or less, 40 μm or less, 30 μm. Hereinafter, it may be 20 μm or less, or 10 μm or less.

Next, the coated coating liquid is dried to form a coating film. The drying temperature can be set appropriately according to the purpose. The drying temperature may be, for example, 30 ° C. or higher, 40 ° C. or higher, 50 ° C. or higher, 60 ° C. or higher, 70 ° C. or higher, 80 ° C. or higher, 90 ° C. or higher, or 100 ° C. or higher, 200 ° C. or lower, 190 ° C. or higher. Hereinafter, it may be 180 ° C. or lower, 170 ° C. or lower, 160 ° C. or lower, 150 ° C. or lower, 140 ° C. or lower, 135 ° C. or lower, 130 ° C. or lower, 120 ° C. or lower, or 110 ° C. or lower. The drying time can also be set appropriately according to the purpose. The drying time may be, for example, 30 seconds or more, 40 seconds or more, 50 seconds or more, or 60 seconds or more, and may be 150 seconds or less, 130 seconds or less, 110 seconds or less, or 90 seconds or less.

Next, the coating film is cured. Curing can be performed by, for example, heating, light irradiation, or the like. The light used for light irradiation may be, for example, ultraviolet light or visible light. The light source for light irradiation can be, for example, a high pressure mercury lamp. The amount of irradiation with the energy radiation source in the ultraviolet curing of accumulative exposure at an ultraviolet wavelength of ^{365nm, 50mJ / cm 2 ~500mJ /} cm 2 is preferred. When the irradiation amount is 50 mJ / cm ² or more, the curing tends to proceed sufficiently, and the hardness of the formed antireflection layer tends to increase. When the irradiation amount is 500 mJ / cm ² or less, coloring of the formed antireflection layer can be prevented.

F. Image display device The circularly polarizing plate with an antireflection layer according to the above items A to E can be applied to an image display device. Therefore, the embodiment of the present invention also includes an image display device using such a circularly polarizing plate with an antireflection layer. The image display device according to the embodiment of the present invention typically includes the circularly polarizing plate with an antireflection layer according to the above items A to E on the visible side thereof. The circularly polarizing plate with an antireflection layer is arranged so that the antireflection layer is on the viewing side. The reflectance of the image display device is preferably 40% or less. In an image display device having such a reflectance, the effect of the circularly polarizing plate with an antireflection layer according to the above items A to E becomes remarkable. Specifically, it is as follows. If the reflectance of the image display device is low, the reflection of the displayed image can be reduced, but the hue unevenness can be easily visually recognized. According to the embodiment of the present invention, by optimizing the configuration of the circularly polarizing plate with the antireflection layer, it is possible to realize an image display device in which reflection of the displayed image is small and hue unevenness is suppressed. .. Typical examples of the image display device include a liquid crystal display device and an organic electroluminescence (EL) display device. An organic EL display device is preferable.

The visual reflectance of the image display device is preferably 1.5% or less, more preferably 1.2% or less. The visual reflectance is the reflectance of the Y value of the XYZ color system, and is the reflectance measured according to JIS Z 8722. ^{The reflected hue b *} value of the image display device is preferably -15 to -6, and more preferably -14 to -8. The reflection hue ^{b * values,} L ^* a * ^{b *} a ^{b *} value of the color system, JIS Z 8722: is measured according to 2009 (spectrophotometer). By using the circularly polarizing plate with the antireflection layer according to the above items A to E, such a visual reflectance and a reflected hue can be realized.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method of each characteristic is as follows.

(1) Reflectance The front reflectance of the antireflection layer used in Examples and Comparative Examples was measured using a spectrocolorimeter "CM-2600d" manufactured by Konica Minolta. The front reflectance was measured by the SCI method. The wavelength of the measurement light was changed from 380 nm to 780 nm, and the wavelength at which the lowest reflectance was observed was defined as the bottom wavelength, and the reflectance at the bottom wavelength was defined as the bottom reflectance.
(2) Thickness Measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000").
(3) Refractive index Measured using a prism coupler SPA-4000 (manufactured by Cylon Technology).
(4) In-plane phase difference Measured using Axoscan (manufactured by Axometrics). The measurement temperature was 23 ° C. Further, Re (450) / Re (550) was calculated as an index of the wavelength dispersion characteristic.
(5) Hue unevenness The circularly polarizing plate with an antireflection layer obtained in Examples and Comparative Examples was cut out to a predetermined size and bonded to a non-alkali glass plate via an acrylic pressure-sensitive adhesive layer to prepare a test sample. This test sample was placed on an organic EL device substitute so that the glass plate surfaces faced each other, and hue unevenness (sujimura) was visually observed under a fluorescent lamp and evaluated according to the following criteria.
A substitute for the organic EL display device was produced as follows. Metal wiring was printed on an acrylic plate so as to have a predetermined reflectance, and this was used as a substitute for an organic EL display device. The metal wiring was printed so that the reflectance of the organic EL display device substitute was 21.88% or 40.34%.
A: Hue unevenness was not substantially observed B: Hue unevenness was observed but was within a practically acceptable range C: Hue unevenness was remarkable and practically unacceptable (6) b ^* Value The test sample prepared in the same manner as in (5) above was placed on an organic EL device substitute so that the glass plate surfaces faced each other, and a spectrophotometer "CM-2600d" manufactured by Konica Minolta Co., Ltd. was used. Was measured.
(7) Y value The test sample prepared in the same manner as in (5) above was placed on an organic EL device substitute so that the glass plate surfaces faced each other, and the spectrocolorimeter "CM-2600d" manufactured by Konica Minolta Co., Ltd. Was measured by a method according to JIS Z 8722.

[Manufacturing Example 1: Fabrication of Polarizer]
A polyvinyl alcohol film having an average degree of polymerization of 2400 and a degree of polymerization of 99.9 mol% and a thickness of 45 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Then, the film was dyed by immersing it in an aqueous solution having a concentration of iodine / potassium iodide (weight ratio = 1/7) at a concentration of 0.3% and stretching it up to 2.6 times. Then, stretching was carried out in a 4 wt% boric acid aqueous solution at 65 ° C. so that the total stretching ratio was 6 times. After stretching, it was dried in an oven at 55 ° C. for 1 minute to obtain a PVA-based polarizer. The thickness of this polarizer was 18 μm, and the water content was 15% by weight.

[Manufacturing Example 2: Fabrication of a retardation film constituting a retardation layer]
[Manufacturing Example 2-1]
To 81.98 parts by mass of isosorbide (hereinafter sometimes abbreviated as "ISB"), 47.19 parts by mass of tricyclodecanedimethanol (hereinafter sometimes abbreviated as "TCDDM") and diphenyl carbonate (hereinafter "" 175.1 parts by mass (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 put into the reaction vessel, and the first stage of the reaction was carried out under a nitrogen atmosphere. As the step of, the heating tank temperature was heated to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes). Next, the pressure was changed from normal pressure to 13.3 kPa, and the generated phenol was extracted from the reaction vessel while raising the heating tank temperature to 190 ° C. in 1 hour. After holding the entire reaction vessel at 190 ° C. for 15 minutes, as the second step, the pressure inside the reaction vessel is set to 6.67 kPa, the heating tank temperature is raised to 230 ° C. in 15 minutes, and the generated phenol is generated. It was taken out of the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250 ° C. in 8 minutes, and the pressure in the reaction vessel was brought to 0.200 kPa or less in order to remove the generated phenol. After reaching a predetermined stirring torque, the reaction was terminated, and the produced reaction product was extruded into water to obtain pellets of a polycarbonate copolymer.

After vacuum-drying the obtained pellets at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 ° C.), T-die (width 200 mm, set temperature: 250 ° C.), chill roll (setting). A resin film was prepared using a film forming apparatus equipped with a temperature (120 to 130 ° C.) and a winder. The obtained long resin film was stretched to obtain a retardation film. By changing the stretching conditions, a retardation film having a Re (550) of 135 nm, 140 nm or 144 nm was obtained. Re (450) / Re (550) was 1.02 for all the retardation films.

[Manufacturing Example 2-2]
A commercially available cycloolefin resin film (manufactured by Zeon Corporation, product name "ZEONORE") was stretched to obtain a retardation film. By changing the stretching conditions, a retardation film having a Re (550) of 140 nm or 144 nm was obtained. Re (450) / Re (550) was 1.02 for all the retardation films.

[Manufacturing Example 3: Preparation of Antireflection Layer]
[Production Example 3-1: Preparation of hard coat layer]
As a resin contained in the hard coat layer, 100 parts by weight of an ultraviolet curable urethane acrylate resin (manufactured by DIC Corporation, trade name "Unidic 17-806", solid content 80%) was prepared. 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), leveling agent (manufactured by DIC Corporation, trade name "GRANDIC PC4100", solid content 10) per 100 parts by weight of the resin solid content of the resin. %) Was mixed by 0.01 parts by weight. This mixture was diluted with a butyl acetate / cyclopentanone mixed solvent (weight ratio 80/20) so that the solid content concentration became 40% to prepare a hard coat layer forming material (coating liquid). The coating liquid was applied to the surface of a base material (TAC film having a thickness of 60 μm) with a wire bar. The coated coating liquid was heated at 80 ° C. for 1 minute and dried to form a coating film. The dried coating film was irradiated with ultraviolet rays having an integrated light intensity of 300 mJ / cm ² with a high-pressure mercury lamp to cure the coating film, and a hard coat film (hard coat layer) was obtained on the substrate.

[Manufacturing Example 3-2: Preparation of Antireflection Layer]
Polyfunctional acrylate containing pentaeristol 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, hollow nanosilica particles (Nikki Catalyst Kasei Kogyo Co., Ltd.) Made by, trade name "Thruria 5320", solid content 20% by weight, weight average particle diameter 75 nm) 100 parts by weight, solid nanosilica particles (manufactured by Nissan Chemical Industry Co., Ltd., trade name "MEK-2140Z-AC", solid content 30 40 parts by weight, weight average particle size 10 nm), 12 parts by weight of fluorine element-containing additive (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KY-1203", solid content 20% by weight), and photopolymerization initiator ( 3 parts by weight of IGM Resins B.V., trade name "Omnirad 907", solid content 100% by weight) was mixed. To the mixture is added a mixed solvent in which TBA (terrific butyl alcohol), MIBK (methyl isobutyl ketone) and PMA (propylene glycol monomethyl ether acetate) are mixed at a ratio of 60:25:15 as a diluting solvent, and the whole solid is added. A coating liquid for forming an antireflection layer was prepared by stirring so that the content was 4% by weight.

The coating liquid for forming the antireflection layer was coated on the surface of the hard coat layer of the laminate of the base material / hard coat layer obtained in Production Example 3-1 with a wire bar. The coated coating liquid was heated at 80 ° C. for 1 minute and dried to form a coating film. The dried coating film was cured by irradiating the dried coating film with ultraviolet rays having an integrated light amount of 300 mJ / cm ² with a high-pressure mercury lamp to form an antireflection layer having a refractive index of 1.36. In this way, a laminate of a base material / hard coat (HC) layer / antireflection layer was produced.
Further, the blending amount of the hollow nanosilica particles was changed to form an antireflection layer having a refractive index of 1.34 or 1.30. Further, the coating thickness of the coating liquid was changed to change the thickness of the antireflection layer formed. An antireflection layer having the refractive index and thickness shown in Table 1 described later was formed.

[Production Example 4: Preparation of active energy ray-curable adhesive]
Radical polymerizable compound (a) 12 parts by weight, radical polymerizable compound (b) 35 parts by weight, radical polymerizable compound (c) 40 parts by weight, oligomer compound (d) 10 parts by weight, photopolymerization initiator (e) 2 The mixture was mixed at a ratio of 1 part by weight and 1 part by weight of the photosensitizer (f) and stirred at 50 ° C. for 1 hour to obtain an active energy ray-curable adhesive. The radically polymerizable compound (a) is HEAA (hydroxyethylacrylamide) (manufactured by KJ Chemicals); the radically polymerizable compound (b) is ACMO (acroylmorpholin) (manufactured by KJ Chemicals); Compound (c) is light acrylate 1,9ND-A (1,9-nonanediol diacrylate) (manufactured by Kyoeisha Chemical Co., Ltd.); Synthetic Co., Ltd.); The photopolymerization initiator (e) is Omnirad907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one) (IGM Resins VV); The sensitizer (f) was KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.).

[Example 1]
The active energy ray-curable adhesive obtained in Production Example 4 was applied to the surface of the substrate of the laminate obtained in Production Example 3 and to one surface of the retardation film obtained in Production Example 2-1. Using a coater (manufactured by Fuji Kikai Co., Ltd.) (cell shape: honeycomb, number of gravure rolls: 1000 lines / inch, rotation speed 140% / pair of line speeds), coating is performed so that the thickness is 0.7 μm, and a manufacturing example. It was attached to both sides of the polarizer obtained in 1 by roll-to-roll. Next, the active energy ray-curable adhesive is cured by irradiating visible light from both sides with an active energy ray irradiator, and then dried with hot air at 70 ° C. for 3 minutes to prevent reflection layer / HC layer / base material / polarized light. A circularly polarizing plate with an antireflection layer having a child / retardation layer configuration was produced. An acrylic pressure-sensitive adhesive layer (23 μm) was provided on the surface of the retardation layer (opposite to the polarizer) of the circularly polarizing plate with an antireflection layer. The obtained circularly polarizing plate with an antireflection layer was placed on an organic EL display device substitute having the reflectance shown in Table 1 and subjected to the evaluations (5) to (7) above. The results are shown in Table 1.

[Examples 2 to 6 and Comparative Examples 1 to 7]
A circularly polarizing plate with an antireflection layer was obtained in the same manner as in Example 1 except that the antireflection layer and the retardation layer were combined as shown in Table 1. The obtained circularly polarizing plate with an antireflection layer was placed on an organic EL display device substitute having the reflectance shown in Table 1 and subjected to the evaluations (5) to (7) above. The results are shown in Table 1.

[evaluation]
As is clear from Table 1, the circularly polarizing plate with an antireflection layer according to the embodiment of the present invention is excellent in all of ^{hue unevenness, b * value and Y value.} If either the bottom wavelength or thickness of the antireflection layer or the Re (550) of the retardation layer is outside the scope of the embodiment of the present invention ^{, at least one of hue unevenness, b *} value and Y value is insufficient. .. As described above, it can be seen that the circularly polarizing plate with an antireflection layer according to the embodiment of the present invention can realize an image display device in which hue unevenness is suppressed. Furthermore, it can be seen that such an effect can be obtained in an image display device having a low reflectance.

The circularly polarizing plate with an antireflection layer of the present invention can be suitably used for an image display device (typically, a liquid crystal display device or an organic EL display device).

10 Polarizing plate 11 Polarizer 12 First protective layer 13 Second protective layer 30 Antireflection layer 40 Phase difference layer 100 Circularly polarizing plate with antireflection layer

Claims (6)

It has a polarizer, an antireflection layer arranged on one side of the polarizer, and a retardation layer arranged on the other side of the polarizer.
The antireflection layer has a refractive index of 1.29 to 1.38, a thickness of 70 nm to 120 nm, and a wavelength in the wavelength range of 380 nm to 780 nm at which the lowest reflectance is obtained in the wavelength range of 400 nm to 600 nm. Exists in
The Re (550) of the retardation layer is 136 nm to 200 nm.
Circularly polarizing plate with antireflection layer. The circularly polarizing plate with an antireflection layer according to claim 1, wherein the reflectance of the antireflection layer is 1.5% or less. The circularly polarizing plate with an antireflection layer according to claim 1 or 2, wherein 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 °. The antireflection layer according to any one of claims 1 to 3, wherein the retardation layer is made of a stretched film of a resin film, and Re (450) / Re (550) is 0.97 to 1.03. Circularly polarizing plate:
Here, Re (450) and Re (550) are in-plane phase differences measured with light having wavelengths of 450 nm and 550 nm at 23 ° C., respectively. The circularly polarizing plate with an antireflection layer according to any one of claims 1 to 4 is provided on the viewing side.
The antireflection layer of the circularly polarizing plate with an antireflection layer is arranged on the viewing side.
Reflectance is 40% or less,
Image display device. The image display device according to claim 5, which is an organic electroluminescence display device.

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