TW201940904A - Phase difference plate, polarizing plate having optical compensation layer, image display device, and image display device having touch panel - Google Patents

Abstract

Provided is a phase difference plate whereby an image display device having a neutral hue in an oblique direction can be realized. In this phase difference plate, the in-plane retardation Re satisfies the expressions 100 nm ≤ Re(550) ≤ 160 nm, Re(450)/Re(550) ≤ 1, and Re(650)/Re(550) ≥ 1, and the Nz coefficient satisfies the expressions Nz(550) < 1, 0 ≤ |Nz(450) - Nz(550)| ≤ 0.1, and 0 ≤ |Nz(650) - Nz(550)| ≤ 0.1.

Description

Phase difference plate, polarizing plate with optical compensation layer, image display device, and image display device with touch panel

The invention relates to a phase difference plate, a polarizing plate with an optical compensation layer, an image display device, and an image display device with a touch panel.

In recent years, with the spread of thin displays, image display devices (organic EL display devices) equipped with organic EL panels have been proposed. The organic EL panel has a highly reflective metal layer, which easily causes problems such as external light reflection or background reflection. Therefore, it is known to prevent such problems by providing a polarizing plate (circular polarizing plate) with an optical compensation layer on the viewing side. It is also known to improve the viewing angle by providing a polarizing plate with an optical compensation layer on the viewing side of the liquid crystal display panel. As a general polarizing plate with an optical compensation layer, it is known to laminate a retardation film and a polarizing element so that their retardation axis and absorption axis form a specific angle (for example, 45 °) corresponding to the application. However, in the case of the prior retardation film used in a polarizing plate with an optical compensation layer, there is a problem that the hue in the oblique direction may produce an undesired coloration.
[Prior technical literature]
[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2016-42185

[Problems to be solved by the invention]

The present invention has been made in order to solve the foregoing problems, and its main object is to provide a retardation plate of an image display device capable of achieving a neutral hue in the oblique direction, and an optical compensation layer with the retardation plate. Polarizing plate, image display device, and touch panel device.
[Technical means to solve the problem]

Regarding the retardation plate of the present invention, the in-plane retardation Re satisfies 100 nm ≦ Re (550) ≦ 160 nm, Re (450) / Re (550) ≦ 1, and Re (650) / Re (550) ≧ 1, Nz The coefficients satisfy Nz (550) <1, 0 ≦ | Nz (450) −Nz (550) | ≦ 0.1 and 0 ≦ | Nz (650) −Nz (550) | ≦ 0.1.
In one embodiment, a laminated structure including a first retardation layer and a second retardation layer is provided, and the in-plane retardation Re of the first retardation layer satisfies Re (450) / Re (550) ≦ 1 and Re (650) / Re (550) ≧ 1, the refractive index characteristics satisfy nx> ny ≧ nz, and the thickness phase retardation Rth of the second phase difference layer satisfies Rth (450) / Rth (550) ≦ 1 and Rth (650) / Rth (550) ≧ 1, and the refractive index characteristics satisfy nz> nx ≧ ny.
Another aspect of the present invention is to provide a polarizing plate with an optical compensation layer. The polarizing plate with an optical compensation layer has an optical compensation layer and a polarizing element composed of the retardation plate, and an angle formed by the late phase axis of the optical compensation layer and an absorption axis of the polarizing element is 35 ° to 55 °.
In one embodiment, the polarizing plate with an optical compensation layer has a conductive layer on the opposite side of the optical compensation layer from the polarizing element.
Another aspect of the present invention provides an image display device. This image display device includes the above-mentioned polarizing plate with an optical compensation layer.
Another aspect of the present invention is to provide an image display device with a touch panel. The image display device with a touch panel includes the polarizing plate with an optical compensation layer, and the conductive layer functions as a touch panel sensor.
[Effect of the invention]

According to the present invention, the in-plane retardation Re of the retardation plate satisfies 100 nm ≦ Re (550) ≦ 160 nm, Re (450) / Re (550) ≦ 1, and Re (650) / Re (550) ≧ 1 , Nz coefficient satisfies Nz (550) <1, 0 ≦ ｜ Nz (450) －Nz (550) ｜ ≦ 0.1 and 0 ≦ ｜ Nz (650) －Nz (550) | ≦ 0.1, and it is used for the optical compensation In the case of a polarizing plate, a polarizing plate with an optical compensation layer having a neutral hue in the oblique direction can be realized.

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

(Definition of terms and signs)
Definitions of terms and symbols in this specification are as follows.
(1) refractive index (nx, ny, nz)
"Nx" refers to the refractive index in the direction where the refractive index in the plane becomes the largest (that is, the direction of the late phase axis), and "ny" refers to the refractive index in the plane that is orthogonal to the late phase axis (that is, the direction of the phase axis), "Nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re (λ)" is the in-plane phase difference measured at 23 ° C under light with a wavelength of λ nm. For example, "Re (550)" is the in-plane phase difference measured at 23 ° C under light with a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), Re (λ) can be obtained by the formula: Re = (nx-ny) × d.
(3) Phase difference in thickness direction (Rth)
"Rth (λ)" is the phase difference in the thickness direction measured at 23 ° C under light with a wavelength of λ nm. For example, "Rth (550)" is the phase difference in the thickness direction measured at 23 ° C under light with a wavelength of 550 nm. When the thickness of the layer (film) is set to d (nm), Rth (λ) can be obtained by the formula: Rth = (nx−nz) × d.
(4) Nz coefficient
The Nz coefficient can be obtained by Nz = Rth / Re.

A. Phase difference plate With respect to the phase difference plate 10 of the present invention, the in-plane phase difference Re satisfies 100 nm ≦ Re (550) ≦ 160 nm, Re (450) / Re (550) ≦ 1, and Re (650) / Re ( 550) ≧ 1, and the Nz coefficient satisfies Nz (550) <1, 0 ≦ | Nz (450) −Nz (550) | ≦ 0.1 and 0 ≦ | Nz (650) −Nz (550) | ≦ 0.1 That is, the above retardation plate exhibits a reverse dispersion wavelength characteristic in which the retardation value becomes larger as the wavelength of the measurement light becomes larger, and the wavelength dependency of the Nz coefficient is small. For measurement light in a wide wavelength range, the refractive index characteristic The relationship of nx>nz> ny is shown. Therefore, when the phase difference plate is used for a polarizing plate with an optical compensation layer, the polarizing plate with an optical compensation layer having a neutral hue in the oblique direction can be realized. The retardation plate may be a single piece or a long shape.

FIG. 1 is a schematic cross-sectional view of a retardation plate 10 according to an embodiment of the present invention. Typically, the retardation plate 10 has a laminated structure in which a first retardation layer 11 and a second retardation layer 12 are laminated. In this case, the in-plane retardation Re of the first retardation layer 11 satisfies Re (450) / Re (550) ≦ 1 and Re (650) / Re (550) ≧ 1, and the refractive index characteristic satisfies nx> ny ≧ nz, the thickness direction retardation Rth of the second retardation layer 12 satisfies Rth (450) / Rth (550) ≦ 1 and Rth (650) / Rth (550) ≧ 1, and the refractive index characteristics satisfy nz> nx ≧ ny.

The in-plane retardation Re (550) of the retardation plate is preferably 120 nm to 150 nm, and more preferably 130 nm to 145 nm. If the in-plane phase difference of the retardation plate is within the above range, the angle formed by the retardation plate and the polarizing element with the retardation axis direction of the retardation plate and the absorption axis direction of the polarizing element becomes about 45 ° or about 135 ° The polarizing plate with an optical compensation layer obtained by laminating in this manner can be used as a circular polarizing plate capable of achieving excellent anti-reflection characteristics.

Regarding the in-plane phase difference of the retardation plate, the value of Re (450) / Re (550) is preferably 0.80 to 0.90, more preferably 0.80 to 0.88, and still more preferably 0.80 to 0.86. The value of Re (650) / Re (550) is preferably 1.01 to 1.20, more preferably 1.02 to 1.15, and even more preferably 1.03 to 1.10. Thereby, the retardation plate can achieve a more excellent reflection hue.

As described above, the Nz coefficient of the retardation plate satisfies Nz (550) <1, 0 ≦ | Nz (450) -Nz (550) | ≦ 0.1 and 0 ≦ | Nz (650) -Nz (550) | ≦ 0.1. Nz (550) is preferably 0.3 to 0.7, more preferably 0.4 to 0.6, still more preferably 0.45 to 0.55, and even more preferably about 0.5. If the Nz coefficient is in this range, the relationship between refractive index characteristics of nx> nz> ny for measured light in a wide range of wavelengths can be achieved, thereby achieving a neutral hue in the oblique direction and an excellent wide viewing angle. Characteristics of polarizing plate with optical compensation layer.

A-1. The first retardation layer is as described above. The in-plane retardation Re of the first retardation layer satisfies Re (450) / Re (550) ≦ 1 and Re (650) / Re (550) ≧ 1, and is refracted. The rate characteristic satisfies nx> ny ≧ nz. The in-plane retardation Re (550) of the first retardation layer is preferably 100 nm to 170 nm, more preferably 110 nm to 160 nm, and even more preferably 120 nm to 150 nm.

Regarding the in-plane phase difference of the first retardation layer, the value of Re (450) / Re (550) is preferably 0.80 to 0.90, more preferably 0.80 to 0.88, and even more preferably 0.80 to 0.86. The value of Re (650) / Re (550) is preferably 1.01 to 1.20, more preferably 1.02 to 1.15, and even more preferably 1.03 to 1.10.

The first retardation layer is typically a retardation film formed of any appropriate resin capable of achieving the above-mentioned characteristics. The retardation film can be obtained by stretching any suitable resin film capable of achieving the above characteristics under any suitable stretching conditions. The above-mentioned stretching may adopt any suitable stretching method and stretching conditions (for example, stretching temperature, stretching magnification, and stretching direction). By appropriately selecting the stretching method and the stretching conditions described above, a stretched film having the desired optical characteristics (for example, refractive index characteristics, in-plane retardation, and Nz coefficient) can be obtained.

The photoelastic coefficient (absolute value) of the retardation film is preferably 14 × 10 ^-12 Pa ^-1 or less. The photoelastic coefficient of the retardation film is preferably 1 × 10 ^-12 Pa ^-1 to 14 × 10 ^-12 Pa ^-1 , and more preferably 2 × 10 ^-12 Pa ^-1 to 12 × 10 ^-12 Pa ^-1 . If the absolute value of the photoelastic coefficient is in this range, the change in the phase difference value can be suppressed even in a high-temperature and high-humidity environment, and excellent reliability can be achieved. In addition, even when the thickness is small, sufficient phase difference can be ensured and the bendability of the image display device (especially the organic EL panel) can be maintained. Furthermore, the change in phase difference caused by the stress during bending can be further suppressed (resulting in Color change of organic EL panel).

The retardation film preferably has a water absorption of 3% or less, more preferably 2.5% or less, and even more preferably 2% or less. By satisfying such a water absorption, it is possible to suppress the change of the display characteristics with time. The water absorption can be determined in accordance with JIS K 7209.

The retardation film preferably has barrier properties against moisture and gases (for example, oxygen). The stretched film at 40 ℃, water vapor permeability (moisture permeability) under the conditions of 90% RH is preferably less than ^{1.0 × 10 -1 g / m 2} /24 hr. From the standpoint of barrier properties, the lower the lower limit of the moisture permeability, the better. The stretched film at 60 ℃, the gas barrier properties under conditions of 90% RH is preferably ^{1.0 × 10 -7 g / m 2} /24 hr ~ 0.5 g / m 2/24 hr, more preferably 1.0 × 10 ^-7 g / ^{m 2/24 hr ~ 0.1 g} / m 2/24 hr. If the moisture permeability and gas barrier properties are within this range, when the polarizing plate with an optical compensation layer is bonded to the organic EL panel, the organic EL panel can be well protected from moisture and oxygen in the air. In addition, both moisture permeability and gas barrier properties can be measured in accordance with JIS K 7126-1.

Examples of the resin constituting the retardation film include polyarylate, polyimide, polyimide, polyester, polyvinyl alcohol, polyfumarate, norylene resin, polycarbonate resin, Cellulose resin, cyclic olefin resin, and polyurethane. These resins can be used alone or in combination. Polycarbonate resin is preferred. Specific examples of the resin are described as, for example, thermoplastic resins in Japanese Patent Laid-Open No. 2015-212828. The entire description of this bulletin is incorporated by reference in this specification.

The glass transition temperature of the polycarbonate resin is preferably 110 ° C or higher and 180 ° C or lower, and more preferably 120 ° C or higher and 165 ° C or lower. If the glass transition temperature is too low, heat resistance tends to deteriorate, dimensional changes may occur after the film is formed, and the image quality of the obtained organic EL panel may be reduced. If the glass transition temperature is too high, the forming stability at the time of film formation may be deteriorated, and the transparency of the film may be impaired. The glass transition temperature can be determined in accordance with JIS K 7121 (1987).

Examples of the extending method include lateral uniaxial extension, free-end uniaxial extension, fixed-end biaxial extension, fixed-end uniaxial extension, and successive biaxial extension. Preferably, the fixed end is uniaxially extended. As a specific example of the uniaxial extension of the fixed end, a method of extending the resin film in the width direction (lateral direction) while moving the resin film in the length direction can be cited. The stretching ratio is preferably 1.1 to 3.5 times. The elongation temperature is preferably Tg-30 ° C to Tg + 60 ° C, and more preferably Tg-10 ° C to Tg + 50 ° C relative to the glass transition temperature (Tg) of the resin film. As another stretching method, a method of continuously extending the elongate resin film obliquely in a direction at a specific angle with respect to the longitudinal direction may be mentioned. Examples of the method of oblique extension include Japanese Patent Laid-Open No. Sho 50-83482, Japanese Patent Laid-Open No. 2-113920, Japanese Patent Laid-Open No. 3-182701, and Japanese Patent Laid-Open No. 2000-9912 The methods described in Japanese Patent Laid-Open No. 2002-86554, Japanese Patent Laid-Open No. 2002-22944, and the like.

The thickness of the retardation film (first retardation layer) is preferably 10 μm to 150 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 70 μm. With such a thickness, the above-mentioned desired in-plane phase difference and Nz coefficient can be obtained.

A-2. As described above, the second retardation layer has a thickness direction retardation Rth that satisfies Rth (450) / Rth (550) ≦ 1 and Rth (650) / Rth (550) ≧ 1, and is refracted. The rate characteristics satisfy nz> nx ≧ ny. The phase difference Rth (550) in the thickness direction of the second retardation layer is preferably -30 nm to -200 nm, more preferably -35 nm to -180 nm, and even more preferably -40 nm to -160 nm.

Regarding the retardation in the thickness direction of the second retardation layer, the value of Rth (450) / Rth (550) is preferably 0.70 to 0.90, more preferably 0.72 to 0.88, and even more preferably 0.74 to 0.86. The value of Rth (650) / Rth (550) is preferably 1.01 to 1.20, more preferably 1.02 to 1.15, and even more preferably 1.03 to 1.10.

The second retardation layer is typically composed of an alignment cured layer of a liquid crystal compound capable of achieving the above-mentioned characteristics. In this specification, the "alignment-cured layer" refers to a layer in which a liquid crystal compound is aligned in a specific direction within the layer, and the alignment state is fixed. In one embodiment, the second retardation layer may include a liquid crystal material that is preferably fixed in a vertical alignment state. The liquid crystal material (liquid crystal compound) capable of vertical alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the method for forming the liquid crystal compound and the retardation layer are described in, for example, Japanese Patent No. 5826759. The entire description of this bulletin is incorporated by reference in this specification. In addition, as other specific examples, it is described in Japanese Patent Publication No. 5401032, Japanese Patent Laid-Open Publication No. 2015-200861, and Japanese Patent Laid-Open Publication No. 2015-169875. The entire description of these publications is for reference. Referenced by this manual. The thickness of the second retardation layer is preferably 0.5 μm to 50 μm, more preferably 0.5 μm to 40 μm, and still more preferably 0.5 μm to 30 μm.

B. Polarizing Plate with Optical Compensation Layer FIG. 2 is a schematic cross-sectional view of a polarizing plate with an optical compensation layer according to an embodiment of the present invention. The polarizing plate 100 with an optical compensation layer in this embodiment includes a polarizing element 20 and an optical compensation layer 10A. The optical compensation layer 10A includes the retardation plate described in the above item A. In one embodiment, the angle formed by the retardation axis of the optical compensation layer and the absorption axis of the polarizing element is 35 ° -55 °. In terms of practicality, a protective layer 30 may be provided on the opposite side of the polarizing element 20 from the optical compensation layer 10A as shown in the example. Further, the polarizing plate with an optical compensation layer may be provided with another protective layer (also referred to as an inner protective layer) between the polarizing element 20 and the optical compensation layer 10A. The inner protective layer is omitted in the illustration. In this case, the optical compensation layer 10A can also function as an inner protective layer. With such a configuration, it is possible to further reduce the thickness of the polarizing plate with an optical compensation layer. Furthermore, if necessary, a conductive layer and a substrate (neither of which is shown) may be sequentially disposed on the optical compensation layer 10A on the opposite side of the polarizing element 20 (that is, outside the optical compensation layer 10A). The substrate is closely laminated on the conductive layer. In the present specification, the “adhesive build-up layer” refers to a direct and fixed build-up layer without an adhesive layer (for example, an adhesive layer or an adhesive layer) interposed between the two layers. The conductive layer and the substrate are typically introduced into the polarizing plate 100 with an optical compensation layer in the form of a laminated body of the substrate and the conductive layer. By further providing a conductive layer and a substrate, the polarizing plate 100 with an optical compensation layer can be preferably used for an image display device with a touch panel.

B-1. Polarizing Element As the polarizing element 20, any suitable polarizing element can be adopted. For example, the resin film forming the polarizing element may be a single-layer resin film, or may be produced using a laminate of two or more layers.

Specific examples of the polarizing element composed of a single-layer resin film include a polyvinyl alcohol (PVA) film, a partially formalized PVA film, and ethylene-acetic acid using a dichroic substance such as iodine or a dichroic dye. Vinyl ester copolymers are obtained by dyeing and extending treatment of hydrophilic polymer films such as partially saponified films; polyene-based alignment films such as dehydrated products of PVA or dehydrochlorinated products of polyvinyl chloride. In terms of excellent optical characteristics, it is preferable to use a polarizing element obtained by dyeing a PVA-based film with iodine and performing uniaxial stretching.

The above-mentioned dyeing with iodine can be performed, for example, by immersing a PVA-based film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Elongation can be performed after the dyeing treatment or simultaneously with the dyeing. Alternatively, dyeing may be performed after stretching. The PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment, and the like, as necessary. For example, by immersing the PVA-based film in water and washing it before dyeing, not only the dirt or anti-blocking agent on the surface of the PVA-based film can be washed, but also the PVA-based film can be swelled to prevent uneven dyeing.

Specific examples of the polarizing element obtained by using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and coating. A polarizing element obtained by laminating a PVA-based resin layer on the resin substrate. A polarizing element obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced, for example, by coating the resin substrate with a PVA-based resin solution and drying it. A PVA-based resin layer is formed on a resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is extended and dyed to make the PVA-based resin layer into a polarizing element. In this embodiment, stretching typically includes immersing a laminate in a boric acid aqueous solution to perform stretching. Further, if necessary, stretching may further include performing air stretching at a high temperature (for example, 95 ° C. or higher) of the laminate before stretching in a boric acid aqueous solution. The obtained laminate of the resin substrate / polarizing element can be used directly (that is, the resin substrate is used as a protective layer of the polarizing element), or the resin substrate can be peeled from the laminate of the resin substrate / polarizing element and peeled off at this stage. Any suitable protective layer can be used for lamination according to the purpose. A detailed description of a method of manufacturing such a polarizer is described in, for example, Japanese Patent Laid-Open No. 2012-73580. The entire description of this bulletin is incorporated by reference in this specification.

The thickness of the polarizing element is preferably 25 μm or less, more preferably 1 μm to 12 μm, still more preferably 3 μm to 12 μm, and even more preferably 3 μm to 8 μm. When the thickness of the polarizing element is within this range, it is possible to satisfactorily suppress curling during heating and obtain good appearance durability during heating.

The polarizing element preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. As described above, the single transmittance of the polarizing element is 43.0% to 46.0%, preferably 44.5% to 46.0%. The degree of polarization of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

B-2. Protective layer The protective layer 30 is formed of any suitable film that can be used as a protective layer of a polarizing element. Specific examples of the material of the main component of the film include cellulose-based resins such as triethylammonium cellulose (TAC), or polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, and poly- Transparent resins such as fluorene imide, polyether fluorene, polyfluorene, polystyrene, polynorylene, polyolefin, (meth) acrylic, and acetate. In addition, thermosetting resins such as (meth) acrylic, urethane, urethane, (meth) acrylic, epoxy, and polysiloxane, or ultraviolet curable can also be mentioned. Resin, etc. In addition, a glassy polymer such as a siloxane polymer may be mentioned. In addition, a polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01 / 37007) may be used. As the material of the film, for example, a resin combination containing a thermoplastic resin having a substituted or unsubstituted fluorene imine group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain can be used Examples of the resin include a resin composition containing an alternating copolymer of isobutylene and N-methylcis butylene diimide, and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

If necessary, the protective layer 30 may be subjected to a surface treatment such as a hard coating treatment, an anti-reflection treatment, an anti-sticking treatment, and an anti-glare treatment. Furthermore, if necessary, the protective layer 30 may be subjected to a process for improving the visibility when viewed through polarized sunglasses (typically, (i) a circular polarizing function is provided, and an ultra-high phase difference is provided). By implementing such processing, even when the display screen is viewed through a polarizing lens such as polarized sunglasses, excellent visibility can be achieved. Therefore, the polarizing plate with an optical compensation layer can also be preferably used for an image display device that can be used outdoors.

The thickness of the protective layer 30 is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm. When the surface treatment is performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

When an inner protective layer is provided between the polarizing element 20 and the optical compensation layer 10A, the inner protective layer is preferably optically isotropic. In this specification, the "optical isotropy" means that the in-plane retardation Re (550) is 0 nm to 10 nm, and the retardation Rth (550) in the thickness direction is -10 nm to +10 nm. The inner protective layer may be composed of any suitable material as long as it is optically isotropic. This material can be appropriately selected from, for example, the materials described above with respect to the protective layer 30.

The thickness of the inner protective layer is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 15 μm to 95 μm.

B-3. Conductive layer or conductive layer with substrate The conductive layer can be patterned if necessary. The conductive portion and the insulating portion can be formed by patterning. As a result, an electrode can be formed. The electrodes can function as touch sensor electrodes that sense contact with the touch panel. The shape of the pattern is preferably a pattern that functions well as a touch panel (for example, a capacitive touch panel). Specific examples include Japanese Patent Publication No. 2011-511357, Japanese Patent Publication No. 2010-164938, Japanese Patent Publication No. 2008-310550, Japanese Patent Publication No. 2003-511799, and Japanese Patent Publication No. The pattern described in 2010-541109.

The conductive layer can be formed on any suitable substrate by any suitable film-forming method (for example, vacuum evaporation method, sputtering method, CVD (Chemical Vapor Deposition) method, ion plating method, spray method, etc.). A metal oxide film is formed on the material. After film formation, heat treatment (for example, 100 ° C to 200 ° C) may be performed as necessary. The amorphous film can be crystallized by performing a heat treatment. Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Indium oxide may be doped with a divalent metal ion or a tetravalent metal ion. Indium-based composite oxides are preferred, and indium-tin composite oxides (ITO) are more preferred. The indium-based composite oxide has the characteristics of high transmittance (for example, 80% or more) in the visible light region (380 nm to 780 nm) and low surface resistance per unit area.

When the conductive layer includes a metal oxide, the thickness of the conductive layer is preferably 50 nm or less, and more preferably 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The surface resistance value of the conductive layer is preferably 300 Ω / □ or less, more preferably 150 Ω / □ or less, and even more preferably 100 Ω / □ or less.

Regarding the conductive layer, the conductive layer can be transferred from the above substrate to the optical compensation layer, and the conductive layer alone can be used as the constituent layer of the polarizing plate with the optical compensation layer, or it can be in the form of a laminated body (conductive layer with the substrate) Laminated on the optical compensation layer. Typically, as described above, the conductive layer and the substrate may be introduced into the polarizing plate with an optical compensation layer in the form of a conductive layer with a substrate.

As a material constituting the substrate, any appropriate resin can be cited. A resin having excellent transparency is preferred. Specific examples include cyclic olefin resins, polycarbonate resins, cellulose resins, polyester resins, and acrylic resins.

Preferably, the substrate is optically isotropic, so the conductive layer can be used as a conductive layer with an isotropic substrate for a polarizing plate with an optical compensation layer. Examples of the material constituting the optically isotropic substrate (isotropic substrate) include a material having no conjugated resin such as a norborne resin or an olefin resin as a main skeleton, and an acrylic resin. Materials having a cyclic structure such as a lactone ring or a glutaridine imine ring in the main chain. If such a material is used, when forming an isotropic substrate, the phase difference that occurs with the alignment of the molecular chain can be suppressed to a low degree.

The thickness of the substrate is preferably 10 μm to 200 μm, and more preferably 20 μm to 60 μm.

B-4. Any appropriate adhesive layer or adhesive layer may be used as the laminated layer of the other layers constituting the polarizing plate with an optical compensation layer of the present invention. The adhesive layer is typically formed of an acrylic adhesive. The adhesive layer is typically formed of a polyvinyl alcohol-based adhesive.

Although not shown, an adhesive layer may be provided on the optical compensation layer 10A side of the polarizing plate 100 with an optical compensation layer. By providing an adhesive layer in advance, it can be easily bonded to other optical members (for example, an organic EL unit). Moreover, it is preferable that a release film is stuck on the surface of this adhesive layer before use.

C. Image display device The image display device of the present invention includes a display unit and a polarizing plate with an optical compensation layer as described in the above item B provided on the viewing side of the display unit. The polarizing plate with an optical compensation layer is laminated so that the optical compensation layer becomes the display unit side (the way the polarizing element becomes the viewing side). An image display device having a polarizing plate with a conductive layer and an optical compensation layer functions as a touch panel sensor through the conductive layer, and can be formed in a display unit (such as a liquid crystal cell, an organic EL unit) and a polarizing element. The so-called image display device with a touch panel is incorporated into the touch sensor.
[Example]

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited to these examples. The measurement method of each characteristic is as follows. In addition, unless otherwise stated, "part" and "%" in an Example and a comparative example are a weight basis.
(1) The thickness was measured using a dial gauge (manufactured by PEACOCK, product name "DG-205 type pds-2").
(2) Phase difference A 50 mm × 50 mm sample was cut out from each phase difference plate as a measurement sample, and was measured using Axoscan manufactured by Axometrics. The measurement wavelengths were 450 nm, 550 nm, and 650 nm, and the measurement temperature was 23 ° C.
The average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive index nx, ny, nz, and Nz coefficients were calculated from the obtained phase difference values.

[Example 1]
1. Production of polycarbonate resin Polymerization was carried out using a batch polymerization device comprising two vertical reactors with stirring wings and a reflux cooler controlled at 100 ° C. Added bis [9- (2-phenoxycarbonylethyl) fluorene-9-yl] methane (compound 3) 29.60 parts by mass (0.046 mol), ISB 29.21 parts by mass (0.200 mol), SPG 42.28 parts by mass (0.139 mol ), DPC 63.77 parts by mass (0.298 mol), and calcium acetate monohydrate 1.19 × 10 ^-2 parts by mass (6.78 × 10 ^-5 mol). After replacing the inside of the reactor with nitrogen under reduced pressure, the reactor was heated with a heating medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature reached 220 ° C 40 minutes after the start of the temperature increase, and the temperature was controlled to maintain the temperature. At the same time, the pressure was reduced. After reaching 220 ° C, it became 13.3 kPa in 90 minutes. The phenol vapor co-produced together with the polymerization reaction was introduced into a reflux cooler at 100 ° C, and a certain amount of monomer components contained in the phenol vapor was returned to the reactor. The uncondensed phenol vapor was introduced to 45 ° C. The condenser is recycled. After introducing nitrogen into the first reactor and temporarily repressing the pressure to atmospheric pressure, the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Subsequently, the temperature rise and pressure reduction in the second reactor were started, and the temperature became 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Thereafter, polymerization is performed until a specific stirring power is obtained. When a specific power is reached, nitrogen is introduced into the reactor, the pressure is repeated, the generated polyester carbonate is extruded into water, and the strand is cut to obtain pellets.
The glass transition temperature of the obtained polycarbonate resin was 130 ° C.
2. Production of phase difference plate
(1) The production of the retardation film used as the first retardation layer is equipped with a single-shaft extruder (manufactured by Isuzu Chemical Machinery, screw diameter 25 mm, cylinder set temperature: 220 ° C), T-die (width 300 mm, set temperature: 220 ° C), cooling roll (set temperature: 120-130 ° C), and film forming device of the winder. The obtained polycarbonate resin is used to make a length of 3 m, a width of 300 mm, and a thickness of 120 μm. Polycarbonate resin film. The obtained polycarbonate film was cut into a length of 150 mm and a width of 120 mm, and Labostretcher KARO IV (manufactured by Bruckner) was used to uniaxially extend the fixed end at a temperature of 134 ° C at a magnification of 2.8 times to obtain a retardation film. (Thickness: 47 μm).
The obtained retardation film exhibited a refractive index characteristic of nx>ny> nz, with Re (450) of 119 nm, Re (550) of 139 nm, Re (650) of 147 nm, Nz (450) of 1.08, and Nz (550) was 1.13 and Nz (650) was 1.15.
Further, Re (450) / Re (550) of the obtained retardation film was 0.86, and Re (650) / Re (550) was 1.06.
(2) Preparation of liquid crystal cured layer used as second retardation layer A liquid crystal coating liquid was prepared according to Example 2 of Japanese Patent No. 5401032, and a liquid crystal cured layer (thickness: 0.9 μm) was formed on a substrate.
The obtained liquid crystal cured layer had Re (550) of 0 nm and Rth (550) of -45 nm, and exhibited a refractive index characteristic of nz> nx = ny. The Rth (450) / Rth (550) of the liquid crystal cured layer was 0.79, and Rth (650) / Rth (550) was 1.07.
(3) Preparation of retardation plate After the retardation film is bonded to the liquid crystal cured layer through an acrylic adhesive, the substrate film is removed, and a retardation film obtained by transferring the liquid crystal cured layer on the retardation film is obtained. (Thickness: 48 μm).
Re (450) of the obtained retardation plate was 120 nm, Re (550) was 141 nm, Re (650) was 150 nm, Nz (450) was 0.76, Nz (550) was 0.79, and Nz (650) was 0.81.
3. Production of conductive layer On the surface of the liquid crystal cured layer side of the above-mentioned retardation plate, a transparent conductive layer (thickness 20 nm) containing indium-tin composite oxide was formed by sputtering, and a retardation film / liquid crystal cured layer / Laminated body of conductive layer. The specific steps are as follows: Under a vacuum environment (0.40 Pa) in which Ar and O ₂ (flow ratio Ar: O ₂ = 99.9: 0.1) are introduced, 10% by weight of tin oxide and 90% by weight of indium oxide are used as a sintered body. Target, and an RF superimposed DC magnetron sputtering method with a film temperature of 130 ° C. and a horizontal magnetic field of 100 mT (discharge voltage 150 V, RF frequency 13.56 MHz, ratio of RF power to DC power (RF power / DC power) is 0.8). The obtained transparent conductive layer was heated in a 150 ° C warm air oven to perform a crystal conversion treatment.
4. Production of polarizing element A roll stretcher was used to roll a strip of polyvinyl alcohol (PVA) -based resin film (manufactured by Kuraray, product name "PE3000") with a thickness of 30 μm so as to be 5.9 times in the longitudinal direction. Uniaxial extension is performed in the length direction, and swelling, dyeing, cross-linking, and washing processes are simultaneously performed, and finally a drying process is performed to produce a polarizing element having a thickness of 12 μm.
Specifically, the swelling treatment is stretched 2.2 times while being treated with pure water at 20 ° C. Next, the dyeing treatment was extended to 1.4 times while adjusting the concentration of iodine in such a way that the single-plate transmittance of the obtained polarizing element became 45.0% and the weight ratio of iodine to potassium iodide was 1: 7 in a 30 ° C aqueous solution. . Furthermore, the cross-linking treatment is a two-stage cross-linking treatment. The first-stage cross-linking treatment is extended to 1.2 times while being treated in an aqueous solution in which boric acid and potassium iodide are dissolved at 40 ° C. The boric acid content of the cross-linked aqueous solution in the first stage was set to 5.0% by weight and the potassium iodide content was set to 3.0% by weight. The cross-linking treatment in the second stage was extended to 1.6 times while being treated in an aqueous solution of boric acid and potassium iodide dissolved at 65 ° C. The boric acid content of the cross-linked aqueous solution in the second stage was set to 4.3% by weight and the potassium iodide content was set to 5.0% by weight. The washing treatment was performed with a potassium iodide aqueous solution at 20 ° C. The potassium iodide content of the rinsed aqueous solution was set to 2.6% by weight. Finally, the drying process was performed at 70 ° C. for 5 minutes to obtain a polarizing element.
5. Production of a polarizing plate with an optical compensation layer A triethyl cellulose film (thickness 40 μm, manufactured by Konica Minolta, trade name "KC4UYW") was attached to one side of the above polarizing element through a polyvinyl alcohol-based adhesive. "). The retardation film side of the retardation plate was bonded to the other side of the polarizing element via a polyvinyl alcohol-based adhesive. Here, the retardation film is bonded so that the retardation axis of the retardation film is 45 ° in the counterclockwise direction with respect to the absorption axis of the polarizing element.
In this way, a polarizing plate with an optical compensation layer having a laminated structure of a protective layer / polarizing element / a retardation film / a liquid crystal cured layer / a conductive layer was obtained.
6. Production of Substitute for Image Display Device Substitute for the organic EL display device was produced as follows. An aluminum vapor-deposited film (manufactured by Toray Advanced Film Co., Ltd., with a trade name of "DMS vapor deposition X-42", thickness 50 μm) was laminated on a glass plate with an adhesive to produce a substitute for organic EL display devices. On the conductive layer side of the obtained polarizing plate with an optical compensation layer, an adhesive layer was formed with an acrylic adhesive, and cut into a size of 50 mm × 50 mm, and then mounted on an organic EL display device substitute.

[Example 2]
In the manufacturing step of the retardation plate, a retardation plate was obtained in the same manner as in Example 1 except that a liquid crystal cured layer formed by setting the thickness of the liquid crystal cured layer to 1.1 μm was used.
Re (550) of the liquid crystal cured layer is 0 nm, Rth (550) is -55 nm, Rth (450) / Rth (550) is 0.80, and Rth (650) / Rth (550) is 1.03.
Re (450) of the obtained retardation plate was 120 nm, Re (550) was 141 nm, Re (650) was 150 nm, Nz (450) was 0.71, Nz (550) was 0.74, and Nz (650) was 0.76.
Except for using the above-mentioned retardation plate, a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

[Example 3]
In the step of manufacturing the retardation plate, a retardation plate was obtained in the same manner as in Example 1 except that a liquid crystal cured layer formed by setting the thickness of the liquid crystal cured layer to 1.3 μm was used.
The Re (550) of the liquid crystal cured layer is 0 nm, Rth (550) is -65 nm, Rth (450) / Rth (550) is 0.80, and Rth (650) / Rth (550) is 1.03.
Re (450) of the obtained retardation plate was 120 nm, Re (550) was 141 nm, Re (650) was 150 nm, Nz (450) was 0.66, Nz (550) was 0.67, and Nz (650) was 0.70.
Except for using the above-mentioned retardation plate, a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

[Example 4]
In the manufacturing step of the retardation plate, a retardation plate was obtained in the same manner as in Example 1 except that a liquid crystal cured layer formed by setting the thickness of the liquid crystal cured layer to 1.7 μm was used.
The Re (550) of the liquid crystal cured layer is 0 nm, Rth (550) is -80 nm, Rth (450) / Rth (550) is 0.80, and Rth (650) / Rth (550) is 1.03.
Re (450) of the obtained retardation plate was 121 nm, Re (550) was 142 m, Re (650) was 150 nm, Nz (450) was 0.59, Nz (550) was 0.60, and Nz (650) was 0.62 .
Except for using the above-mentioned retardation plate, a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

[Example 5]
In the manufacturing step of the retardation plate, a retardation plate was obtained in the same manner as in Example 1 except that a liquid crystal cured layer formed by setting the thickness of the liquid crystal cured layer to 1.9 μm was used.
Re (550) of the liquid crystal cured layer is 0 nm, Rth (550) is -90 nm, Rth (450) / Rth (550) is 0.80, and Rth (650) / Rth (550) is 1.03.
Re (450) of the obtained retardation plate was 120 nm, Re (550) was 141 m, Re (650) was 149 nm, Nz (450) was 0.47, Nz (550) was 0.48, and Nz (650) was 0.50 .
Except for using the above-mentioned retardation plate, a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

[Comparative Example 1]
Let the weight of the side-chain liquid crystal polymer represented by the following chemical formula (I) (the numbers 65 and 35 in the formula represent the mole% of the monomer unit, expressed as a block polymer for convenience: weight average molecular weight 5000) Parts, 80 parts by weight of a polymerizable liquid crystal (manufactured by BASF, trade name "PaliocolorLC242") and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name "Irgacure 907") were dissolved. A liquid crystal coating liquid was prepared at 200 parts by weight of cyclopentanone. Next, the coating solution was applied to a substrate film (norylene resin film: manufactured by Japan Zeon Corporation, trade name "ZEONEX") with a bar coater, and then dried by heating at 80 ° C for 4 minutes. This aligns the liquid crystal. The liquid crystal layer is irradiated with ultraviolet rays to harden the liquid crystal layer, thereby forming a liquid crystal cured layer (thickness: 1 μm) as a second retardation layer on the substrate. This layer has Re (550) of 0 nm and Rth (550) of -100 nm (nx: 1.5326, ny: 1.5326, nz: 1.6550), and exhibits a refractive index characteristic of nz> nx = ny.
[Chemical 1]

A phase difference plate was obtained in the same manner as in Example 1 except that the above-mentioned liquid crystal cured layer was used.
Re (450) of the obtained retardation plate was 119 nm, Re (550) was 139 nm, Re (650) was 147 nm, Nz (450) was 0.31, Nz (550) was 0.52, and Nz (650) was 0.60.
Except for using the above-mentioned retardation plate, a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

[Comparative Example 2]
A retardation film produced in the same manner as in Example 1 was used as a retardation film, and a polarizing plate with an optical compensation layer and an organic EL display device substitute were obtained in the same manner as in Example 1.

＜ Evaluation ＞
The following evaluations were performed on the organic EL display device substitutes of Examples and Comparative Examples. The evaluation results are shown in Table 1.
(1) Reflectivity and reflection hue Using a replacement organic EL display device as a sample, the frontal reflectance and frontal reflection hue were measured using a spectrophotometer CM-2600d manufactured by Konica Minolta Co., Ltd. Frontal reflectance is measured by the SCI (Specular Component Included) method. The front reflection hue was evaluated as a ^* b ^{* on the} chromaticity diagram from the distance Δa ^* b ^* from the achromatic color.
(2) Reflectivity and reflection hue in the oblique direction Using a substitute for an organic EL display device as a sample, DMS 505 manufactured by Konica Minolta Co., Ltd. was used to measure the reflectance and reflection hue in the oblique direction. The reflectance in the oblique direction was evaluated as the average value of the apparent reflectance Y at four points: polar angle 60 °, azimuth angles 0 °, 45 °, 90 °, and 135 °. The reflection hue in the oblique direction is the two points of the reflection hue in the oblique direction when the axial phase reference is tilted by 60 ° on the a ^* b ^* chromaticity diagram and the reflection hue when the retarded axial reference angle is 60 ° in the measurement. The distance Δa ^* b ^* was evaluated.

[Table 1]

Compared with the organic EL display device substitute of the comparative example, the organic EL display device substitute of the example has lower reflection strength and better reflection hue.
[Industrial availability]

The polarizing plate with an optical compensation layer provided with the retardation plate of the present invention is suitable for use in an image display device such as an organic EL panel.

10‧‧‧ retardation plate

10A‧‧‧Optical compensation layer

11‧‧‧The first phase difference layer

12‧‧‧ 2nd phase difference layer

20‧‧‧ polarizing element

30‧‧‧ protective layer

100‧‧‧ polarizing plate with optical compensation layer

FIG. 1 is a schematic cross-sectional view of a retardation plate according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a polarizing plate with an optical compensation layer according to an embodiment of the present invention.

Claims (6)

A retardation plate whose in-plane retardation Re satisfies 100 nm ≦ Re (550) ≦ 160 nm, Re (450) / Re (550) ≦ 1, and Re (650) / Re (550) ≧ 1, The Nz coefficient satisfies Nz (550) <1, 0 ≦ | Nz (450) -Nz (550) | ≦ 0.1 and 0 ≦ | Nz (650) -Nz (550) | ≦ 0.1, Here, Re (450), Re (550), and Re (650) represent the in-plane phase differences measured at 23 ° C under light with a wavelength of 450 nm, 550 nm, and 650 nm, respectively. Nz (450), Nz (550) and Nz (650) represent the Nz coefficients measured at 23 ° C under light with a wavelength of 450 nm, 550 nm, and 650 nm, respectively. For example, the retardation plate of claim 1 has a laminated structure in which a first retardation layer and a second retardation layer are laminated, The in-plane retardation Re of the first retardation layer satisfies Re (450) / Re (550) ≦ 1 and Re (650) / Re (550) ≧ 1, and the refractive index characteristic satisfies nx> ny ≧ nz, The thickness retardation Rth of the second retardation layer satisfies Rth (450) / Rth (550) ≦ 1 and Rth (650) / Rth (550) ≧ 1, and the refractive index characteristic satisfies nz> nx ≧ ny, Here, Rth (450), Rth (550), and Rth (650) represent thickness direction phase differences measured at 23 ° C under light having a wavelength of 450 nm, 550 nm, and 650 nm, respectively. A polarizing plate with an optical compensation layer having an optical compensation layer and a polarizing element composed of a retardation plate as in claim 1 or 2, and The angle formed by the retardation axis of the optical compensation layer and the absorption axis of the polarizing element is 35 ° to 55 °. For example, the polarizing plate with an optical compensation layer in claim 3 has a conductive layer on the opposite side of the optical compensation layer from the polarizing element. An image display device having a polarizing plate with an optical compensation layer as claimed in claim 3. An image display device with a touch panel having a polarizing plate with an optical compensation layer as in claim 4; The conductive layer functions as a touch panel sensor.