KR102126056B1 - Polarizing plate for light emitting display apparatus and light emitting display apparatus compsiring the same - Google Patents

Abstract

A polarizing film and a laminated retardation film formed on one surface of the polarizing film, the laminated retardation film includes a second phase difference film and a first phase difference film sequentially stacked from the polarization film, and the laminated phase difference film has a wavelength of 550 nm In the degree of biaxiality (NZ) is -0.2 to 0.2, the second phase difference film is a positive C plate, and the first phase difference film is a reverse wavelength dispersive positive A plate, including a polarizing plate for a light emitting display device and the same A light emitting display device is provided.

Description

Polarizing plate for light-emitting display device and light-emitting display device including the same {POLARIZING PLATE FOR LIGHT EMITTING DISPLAY APPARATUS AND LIGHT EMITTING DISPLAY APPARATUS COMPSIRING THE SAME}

The present invention relates to a polarizing plate for a light emitting display device and a light emitting display device comprising the same.

In the organic light emitting display device, external light is reflected by a display element inside the organic light emitting device panel. The reflected external light is mixed with light emitted from the organic light emitting device, and there is a problem in that visibility is deteriorated when viewed from the outside. In order to solve this, there is a method of preventing the incident light from coming out by linearly polarizing and circularly polarizing external light incident into the organic light emitting device using a polarizing film and a retardation layer.

The side reflectance can be lowered by combining a 1/2 retardation film and a 1/4 retardation film as a retardation layer. However, it is necessary to lower the front reflectance along with the side reflectance, and it is necessary to lower the difference between the front reflectance and the side reflectance to ensure uniform reflectance across the screen of the display device. In addition, it is necessary to lower the color shift at the side to improve the color sense of the side, and also to improve the color sense at the front.

Background art of the present invention is described in Japanese Patent Publication No. 2014-032270.

An object of the present invention is to provide a polarizing plate for a light emitting display device that can lower the front reflectance and side reflectance.

Another object of the present invention is to provide a polarizing plate for a light emitting display device that can secure a uniform reflectance across the screen of a display device by lowering the difference between front reflectance and side reflectance.

Another object of the present invention is to provide a polarizing plate for a light-emitting display device that can improve color sense on the side surface by improving side color shift.

Another object of the present invention is to provide a polarizing plate for a light emitting display device that can improve the color sense in the front.

The polarizing plate for a light emitting display device of the present invention includes a polarizing film and a laminated retardation film formed on one surface of the polarizing film, and the laminated retardation film includes a second phase difference film and a first phase difference film sequentially stacked from the polarizing film. And, the laminated retardation film has a degree of biaxiality (NZ) of -0.2 to 0.2 at a wavelength of 550 nm, the second phase difference film may be a positive C plate, and the first phase difference film may be a reverse wavelength dispersive positive A plate. .

The light emitting display device of the present invention may include a polarizing plate for a light emitting display device of the present invention.

The present invention provides a polarizing plate for a light emitting display device that can lower the front reflectance and side reflectance.

The present invention has provided a polarizing plate for a light emitting display device that can lower the difference between front reflectance and side reflectance to ensure uniform reflectance across the entire screen of the display device.

The present invention has provided a polarizing plate for a light emitting display device that can improve the color sense on the side by improving the side color shift.

The present invention has provided a polarizing plate for a light emitting display device that can improve the color sense from the front.

1 is a cross-sectional view of a polarizing plate for a light emitting display device according to an embodiment of the present invention.

Embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification.

In this specification, "upper part" and "lower part" are based on the drawings, and are not necessarily fixed to the upper part and the lower part, and "upper part" is changed to "lower part" and "lower part" is changed to "upper part" according to the viewing time. Can.

In this specification, "in-plane retardation (Re)" is represented by Equation A below, "thickness phase retardation (Rth)" is represented by Equation B below, and "degree of biaxiality (NZ)" is represented by Equation C below, These are all measured at a wavelength of 550 nm:

<Equation A>

Re = (nx-ny) x d

<Equation B>

Rth = ((nx + ny)/2-nz) x d

<Equation C>

NZ = (nx-nz)/(nx-ny)

(In the formulas A, B, and C, nx, ny, and nz are the refractive indexes in the x-axis, y-axis, and z-axis directions of the retardation film at a wavelength of 550 nm, respectively, and d is the thickness of the retardation film (unit: nm)) .

In this specification, "front", "side" is based on the horizontal direction, by (φ, θ) by a spherical coordinate system (spherical coordinate system), the front is (0 ~ 360 °, 5 °), the left When the end point is (180°, 90°) and the right end point is (0°, 90°), the side means (0~360°, 60°).

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 1.

Referring to FIG. 1, the polarizing plate 10 may include a polarizing film 300 and a laminated retardation film stacked on one surface of the polarizing film 300. The laminated retardation film may include a first phase difference film 100 and a second phase difference film 200 sequentially stacked from the polarizing film 300.

The stacked retardation film may have a degree of biaxiality (NZ) of -0.2 to 0.2 at a wavelength of 550 nm. In the above range, the front reflectance and side reflectance can be reduced, the side color shift and the front color sense can be improved, and the difference between the front reflectance and the side reflectance can be lowered to ensure uniform reflectance across the screen of the display device. . For example, the laminated retardation film may have a degree of biaxiality (NZ) of -0.1 to 0.2 and -0.1 to 0.18 at a wavelength of 550 nm. The degree of biaxiality (NZ) at a wavelength of 550 nm of the laminated retardation film is in the first phase difference film and the second phase difference film having the phase difference described below, and the thickness direction phase difference (Rth) at a wavelength of 550 nm of the second phase difference film is -190 nm to It could come out by adjusting to -110nm. When the optical display device equipped with the polarizing plate is not driven in a power-off state, the “front color improvement” may cause stains or mura on the screen or diverge reflected light even if light is irradiated to the screen of the display device from external lighting. It means improving black vision by making neutral black without losing phenomenon.

Second phase difference film

The second phase difference film 200 is formed on the lower surface of the first phase difference film 100, and can transmit a circularly polarized light emitted from the first phase difference film 100 to produce an antireflection effect. In one embodiment, the first phase difference film from the polarizing film 300 by an adhesive layer, an adhesive layer or a point adhesive layer; Adhesive layer, adhesive layer or point adhesive layer; It may be laminated in the order of the second phase difference film.

The second phase difference film 200 may be disposed on the light exit surface of the external light in the first phase difference film 100 when external light, for example, sunlight is incident on the polarizing film 300.

The second phase difference film 200 is a positive C plate and may be a uniaxial optical film having a refractive index distribution of nz>nx=ny. nx=ny means when nx and ny are completely the same and substantially the same, and nx-ny may be 0.01 or less, for example, 0 to 0.01.

The second phase difference film 200 may have an in-plane retardation (Re) of 5 nm or less at a wavelength of 550 nm, for example, 2 nm or less. In the above range, the influence on the front phase difference is low, so that the side reflectance may be improved without a decrease in the front reflectance.

The second phase difference film 200 may have a thickness direction retardation (Rth) of -190nm to -110nm at a wavelength of 550nm. In the above range, by setting the degree of biaxiality (NZ) of the laminated retardation film to be -0.2 to 0.2, the front reflectance and side reflectance can be reduced, the side color shift and the color sense at the front can be improved, and the front reflectance It is possible to secure a uniform reflectance across the entire screen of the display device by lowering the difference between the and side reflectances. For example, the second phase difference film may have a thickness direction retardation (Rth) of -150 nm to -110 nm, -140 nm to -110 nm, -130 nm to -110 nm at a wavelength of 550 nm.

The second phase difference film 200 may have a degree of biaxiality (NZ) of -300 or less at a wavelength of 550 nm, for example, -800 to -300, -800 to -550. In the above range, the Re of the second phase difference film is low, and there may be an effect of simultaneously improving the performance of the front reflectance and the performance of the side reflectance.

The second phase difference film 200 may have a thickness of 0.1 μm to 100 μm, for example, 0.1 μm to 100 μm, 0.1 μm to 70 μm, and 0.1 μm to 50 μm. In the above range, it can be used for a polarizing plate, it is possible to secure the phase difference in the thickness direction.

The second phase difference film 200 may be a laminate of one or more retardation films or two or more retardation films. A laminate of two or more sheets can be produced by laminating a retardation film with an adhesive layer, an adhesive layer, or a point adhesive layer, respectively.

The second phase difference film 200 may include at least one of an optically transparent resin film or a liquid crystal film. For example, by using a liquid crystal film as the second phase difference film, it is easy to reach the phase difference of the present invention, and the second phase difference film can be thinned.

The resin film can be produced by melting and extruding a resin and stretching it. The resin includes cyclic polyolefin-based resins, polycarbonate-based resins, polyethylene terephthalate (PET), etc., including cellulose ester-based resins including triacetyl cellulose, amorphous cyclic olefin polymers (COP), and the like. Polyacrylate-based resins, including polyester resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethylmethacrylate resins, etc. It may include one or more of polyvinyl alcohol-based resin, polyvinyl chloride-based resin, polyvinylidene chloride-based resin, acrylic resin. When the second phase difference film is a resin film, Re, Rth, and NZ can be obtained by adjusting the thickness, stretching ratio, and stretching temperature of the film before stretching.

The liquid crystal film may include a liquid crystal layer including at least one polymerizable liquid crystal compound of nematic liquid crystal or discotic liquid crystal. The liquid crystal compound may be oriented in homogeneous alignment. The homogeneous orientation means a state in which the liquid crystal compound is arranged parallel to the second phase difference film plane direction. For example, the second phase difference film may include a nematic liquid crystal compound oriented in a homogeneous orientation. When the second phase difference film is a liquid crystal film, Re, Rth, and NZ can be obtained by adjusting the degree of liquid crystal alignment. The degree of liquid crystal alignment may be adjusted by an alignment layer during liquid crystal alignment.

In one embodiment, the nematic liquid crystal compound may include a liquid crystal compound having a polymerizable functional group. The polymerizable functional group is a (meth)acryloyl group, (meth)acrylate group, cinnamoyl group, cinnamillidene group, (meth)acryloyl group-containing group, (meth)acrylate group-containing group, coumarin group, benzofe It may be a non-group, a quinone group, a cyano group, a cyanate group, an isocyanate group, and the like.

In one embodiment, the nematic liquid crystal compound may be represented by Formula 1 below, but the present invention is not limited to Formula 1 below:

<Formula 1>

Z ^1- (Y ¹ -A ¹ ) v-Y ² -M-Y ^3- (A ² -Y ⁴ )w-Z ²

(In Formula 1, Y ¹ , Y ² , Y ³ , Y ⁴ are each independently a single bond, -O-, -S-, -CO-O-, -O-CO-, -O-CO-O -, -NR ¹ -CO-O-, -O-CO-NR ¹ -or -NR ¹ -CO-NR ¹ -, where R ¹ is an alkyl group having 1 to 4 carbon atoms or hydrogen,

A ¹ and A ² are each independently an alkylene group having 1 to 10 carbon atoms,

v, w are each independently 0 or 1,

M is-(TY ⁵ )m-T-(where T is a substituted or unsubstituted alicyclic divalent organic group having 3 to 10 carbon atoms, substituted or unsubstituted aromatic divalent having 6 to 20 carbon atoms, An organic group, a substituted or unsubstituted heterocyclic divalent organic group having 3 to 10 carbon atoms, or a substituted or unsubstituted divalent organic group having 4 to 20 carbon atoms, and Y ⁵ is a single bond, -CO-O-, -O-CO-, -CH ₂ O-, -OCH ₂ -, -CO-S-, -S-CO-, -CH ₂ -S-, -S-CH ₂ -,- CH=N-, or -N=CH-, m is 1, 2, 3 or 4)

Z ¹ and Z ² are each independently a polymerizable functional group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a cyano group, and at least one of Z ¹ and Z ² is a polymerizable functional group)

The "substituted or unsubstituted" means that one or more hydrogen atoms of the functional group are substituted with an alkyl group having 1 to 10 carbon atoms or a hydroxyl group.

In another embodiment, the nematic liquid crystal compound may include, but is not limited to, one or more of the liquid crystal compounds of Formulas 11 to 20:

<Formula 11>

<Formula 12>

<Formula 13>

<Formula 14>

<Formula 15>

<Formula 16>

<Formula 17>

<Formula 18>

<Formula 19>

<Formula 20>

Liquid crystal compounds may be commercially sold or prepared by conventional methods known to those skilled in the art.

The second phase difference film is coated with a composition for a second phase difference film containing a liquid crystal compound, dried, and then irradiated with one or more of active energy rays and heat on the dried coating material, and heated and cooled by irradiating the applied coating material. Can be manufactured. After heating, the liquid crystal orientation may be further fixed. The second phase difference film may be formed without an alignment layer or may be formed by aligning a liquid crystal through an alignment layer with a rubbing agent.

The composition for the second phase difference film may be prepared by dissolving the liquid crystal in a solvent. The solvent is an aliphatic hydrocarbon such as hexane, an aromatic hydrocarbon such as toluene, xylene, benzene, monochlorobenzene, dichlorobenzene, halogenated hydrocarbons such as dichloromethane, dichloroethane, alicyclic hydrocarbons such as cyclohexane Etc., ketones such as acetone, methyl ethyl ketone, cyclohexanone, ethers such as dioxane, tetrahydrofuran, etc., amides such as dimethylformamide. The composition for the second phase difference film may be applied by a conventional method such as a spin coater, a slit coater, a spray coater, and a roll coater. The composition for the second phase difference film is applied and dried. In the drying process, the coating material is dried at 50°C to 65°C. The dried coating is irradiated with one or more of UV and heat. The irradiation may be ultraviolet (UV) infrared rays, visible light, or the like, but may be irradiated with ultraviolet rays having a wavelength of 200 nm to 500 nm and 250 nm to 400 nm, for example. The irradiated coating is heated and cooled. The heating temperature can be performed at 50°C to 150°C, for example 40°C to 100°C.

The second phase difference film 200 may further include a conventional additive in addition to at least one of an optically transparent resin and a liquid crystal compound. The additive may include, but is not limited to, one or more of heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, crosslinking agents, and thickeners.

Although not illustrated in FIG. 1, an adhesive layer is further formed on the other surface of the second phase difference film 200, so that a polarizing plate may be stacked on a panel of a light emitting display device.

First phase difference film

The first phase difference film 100 is formed on the lower surface of the polarizing film 300, and transmits linearly polarized light from the polarizing film 300, thereby providing an anti-reflective effect. The first phase difference film 100 may be disposed on the light exit surface of the external light in the polarizing film 300 when external light, for example, sunlight is incident on the polarizing film 300.

The first phase difference film 100 is a positive A plate and may have a uniaxial optical film having a refractive index distribution of nx>ny=nz. ny=nz means the case where ny and nz are completely the same, and substantially the same, and ny-nz may be 0.1 or less.

The first phase difference film 100 exhibits reverse wavelength dispersion. Through this, the phase difference value becomes constant, and light leakage of a specific wavelength is unlikely to occur, and color shift can be improved. In one embodiment, with respect to the wavelength dispersion property of the first phase difference film, the ratio of the in-plane retardation value at a wavelength of 450 nm to the in-plane retardation value at a wavelength of 550 nm (Re(450)/Re(550)) is 0.75 to 0.86, For example, it may be 0.78 to 0.85. Within this range, it is possible to ensure front reflectance.

The first phase difference film 100 may have an in-plane retardation (Re) of 130 nm to 150 nm, for example, 135 nm to 145 nm at a wavelength of 550 nm. In the above range, as the first phase difference film having reverse wavelength dispersion, an antireflection effect may be obtained.

The first phase difference film 100 may have a thickness direction retardation (Rth) of 60 nm to 80 nm, for example, 65 nm to 75 nm at a wavelength of 550 nm. In the above range, the alignment characteristics may be appropriate to have an antireflection effect.

The first phase difference film 100 may have a degree of biaxiality (NZ) of 0.9 to 1.3 at a wavelength of 550 nm, for example, 0.9 to 1.2, 0.95 to 1.2. In the above range, acting as a positive A plate may have an excellent anti-reflective effect when applied to a polarizing plate.

The first phase difference film 100 may have a thickness of 0.5 μm to 10 μm, for example, 1 μm to 6 μm, and 2 μm to 4 μm. In the above range, it can be used for a polarizing plate, it is possible to secure the phase difference in the thickness direction.

The first phase difference film 100 may be a laminate of one or more retardation films or two or more retardation films. A laminate of two or more sheets can be produced by laminating a retardation film with an adhesive layer, an adhesive layer, or a point adhesive layer, respectively.

The first phase difference film 100 may include at least one of an optically transparent resin film or a liquid crystal film. The resin film may be produced by melting and extruding the resin and stretching it, and the resin film is as described above. When the first phase difference film is a resin film, Re, Rth, and NZ can be obtained by adjusting the thickness, stretching ratio, stretching temperature, etc. of the film before stretching.

A liquid crystal film may be used as the first phase difference film. The liquid crystal film may include a liquid crystal layer in which one or more liquid crystal compounds of nematic liquid crystal and discotic liquid crystal are homeotropically aligned. The homeotropic alignment refers to a state in which the liquid crystal compounds are arranged parallel to the normal direction of the first phase difference film. For example, the first phase difference film may include a nematic liquid crystal compound oriented in a homeotropic orientation. When the first phase difference film is a liquid crystal film, Re, Rth, and NZ can be obtained by adjusting the degree of liquid crystal alignment.

The first phase difference film 100 may further include a conventional additive in at least one of an optically transparent resin and a liquid crystal compound. The additive is as described above.

Lamination Phase difference film

The laminated retardation film may include a laminate of the first phase difference film 100 and the second phase difference film 200 sequentially stacked from the polarizing film 300.

The laminated retardation film may have an in-plane retardation (Re) of 130 nm to 150 nm, for example, 135 nm to 145 nm at a wavelength of 550 nm. In the above range, an appropriate ellipticity effect is exhibited by the antireflection film, and there may be an antireflection effect.

The laminated retardation film may have a thickness retardation (Rth) of -80 nm to -45 nm at a wavelength of 550 nm, for example, -75 nm to -45 nm. In the above range, the front reflectance and side reflectance can be reduced, the side color shift can be improved, and the difference between the front reflectance and the side reflectance can be lowered to ensure uniform reflectance across the screen of the display device, and from the front Can improve the color.

Re, Rth, and NZ of the laminated retardation film can be obtained by adjusting Re, Rth, and NZ of each of the first phase difference film and the second phase difference film.

In one embodiment, the first phase difference film and the second phase difference film may be liquid crystal films, respectively, as a laminated retardation film. For example, the first phase difference film may be a nematic liquid crystal film, and the second phase difference film may be a nematic liquid crystal film.

In the laminated retardation film, the second phase difference film and the first phase difference film may be laminated by one or more of an adhesive layer, an adhesive layer, and a primer layer. Alternatively, in the laminated retardation film, the second phase difference film may be formed by directly contacting the first phase difference film without an adhesive layer, an adhesive layer, or the like.

The adhesive layer may be formed of a conventional pressure-sensitive adhesive. For example, the pressure-sensitive adhesive may include at least one of a (meth)acrylic adhesive resin, a urethane adhesive resin, and a silicone adhesive resin, and may include, for example, a (meth)acrylic adhesive resin. The primer layer may be formed of a composition containing at least one of (meth)acrylic resin, urethane resin, and urethane (meth)acrylic resin. The composition may further increase the mechanical strength of the primer layer by further including a thermal initiator.

The laminated retardation film may have a thickness of 1 μm to 100 μm, for example, 2 μm to 65 μm, and 3 μm to 50 μm. In the above range, it can be used in a polarizing plate for a light emitting display device.

The laminated retardation film may have a total light transmittance of 90% or more and a haze of 1% or less in the visible light region. In the above range, it can be used in a polarizing plate for a light emitting display device.

Polarizing film

The polarizing film 300 is formed on the upper surface of the first phase difference film 100, and linearly polarizes external light to transmit it to the first phase difference film 100, thereby providing an antireflection effect.

In one embodiment, the polarizing film may include a polyvinyl alcohol-based polarizer dyed with iodine or the like on the polyvinyl alcohol-based film or a polyene-based polarizer by dehydration of the polyvinyl alcohol-based film. The polarizer may have a thickness of 5 μm to 50 μm. It can be used for a display device in the above range.

In another embodiment, the polarizing film may include the above-described polarizer and a protective layer formed on at least one surface of the polarizer. The protective layer may include one or more of an optically transparent, protective film or protective coating layer.

The protective film may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, an additional stretching process may be added. The resin includes cyclic polyolefin-based resins, polycarbonate-based resins, polyethylene terephthalate (PET), etc., including cellulose ester-based resins including triacetyl cellulose, amorphous cyclic olefin polymers (COP), and the like. Polyacrylate-based resins, including polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethylmethacrylate resins, and the like, It may include at least one of polyvinyl alcohol-based resin, polyvinyl chloride-based resin, polyvinylidene chloride-based resin.

The protective coating layer may be formed of an active energy ray-curable resin composition comprising an active energy ray-curable compound and a polymerization initiator. The active energy ray-curable compound may include at least one of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationic polymerizable curable compound may be an epoxy-based compound having at least one epoxy group in the molecule, or an oxetane-based compound having at least one oxetane ring in the molecule. The radically polymerizable curable compound may be a (meth)acrylic compound having at least one (meth)acryloyloxy group in the molecule. The thickness of the protective layer may be 5 μm to 200 μm, specifically, 30 μm to 120 μm, for the protective film type may be 50 μm to 100 μm, and for the protective coating layer type may be 5 μm to 50 μm. It can be used for a display device in the above range. A functional coating layer such as a hard coating layer, an anti-fingerprint layer, and an anti-reflection layer may be further formed on one or both sides of the protective layer.

Although not shown in FIG. 1, the polarizing film may be laminated on the upper surface of the first phase difference film by an adhesive, an adhesive, or a point adhesive. The adhesive, pressure-sensitive adhesive, or point-adhesive can use any kind known to those skilled in the art.

The angle formed by the fast axis of the first phase difference film 100 and the absorption axis of the polarizing film 300 is -90° to 0°, for example, -70° to -30°, -60° to- It can be 40°. In the above range, antireflection characteristics may be excellent in both the front and side surfaces.

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described.

The polarizing plate of this embodiment is substantially the same as the polarizing plate of an embodiment of the present invention, except that a base film is further formed on the lower surface of the first phase difference film.

The base film is formed on the lower surface of the first phase difference film, and when the first phase difference film is a liquid crystal film, facilitates formation of an alignment film for forming the first phase difference film, and can protect the laminated retardation film. The base film may include a conventional polymer film. For example, it may be a cellulose-based film including a triacetyl cellulose (TAC) film, a polyester film such as a polyethylene terephthalate film, a polycarbonate film, and the like, but is not limited thereto. The base film can be easily released from the first phase difference film by being subjected to a release treatment.

In one embodiment, the base film may have an in-plane retardation (Re) of 5 nm or less, for example, 3 nm or less at a wavelength of 550 nm. In the above range, it may not affect the phase difference of the laminated retardation film.

The light emitting display device of the present invention may include a polarizing plate for a light emitting display device of the present invention. The light emitting display device may be a device including a light emitting element. The light emitting device includes an organic or organic-inorganic light emitting device, and means a device including a light emitting diode (LED), an organic light emitting diode (OLED), a quantum dot light emitting diode (QLED), and a phosphor. can do. For example, the light emitting display device may include an organic light emitting device display device.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is provided as a preferred example of the present invention and cannot be interpreted as limiting the present invention by any means.

Example One

The polyvinyl alcohol film was stretched 3 times at 60°C, adsorbed iodine, and then stretched 2.5 times in a boric acid aqueous solution at 40°C to prepare a polarizer. A polarizing film was prepared by bonding triacetylcellulose films (ZRG40SL, Fuji) to one side of the polarizer and the other side of the polarizer with an epoxy-based UV adhesive for a polarizing plate.

As the first phase difference film and the second phase difference film, a film having the specifications in Table 1 below was used. A laminated phase difference film was prepared by laminating the first phase difference film and the second phase difference film with an acrylic pressure-sensitive adhesive. The phase difference between the first phase difference film and the second phase difference film was measured using an Axoscan apparatus at a wavelength of 550 nm. As a liquid crystal of the second phase difference film, a liquid crystal compound composed of the liquid crystal of Formula 11 was used, and the phase difference of Table 1 was implemented by adjusting the degree of alignment.

A laminated retardation film was laminated on one side of the polarizing film with an acrylic pressure-sensitive adhesive, to prepare a polarizing plate in which a polarizing film, an acrylic pressure-sensitive adhesive layer, a first phase difference film, an acrylic pressure-sensitive adhesive layer, and a second phase difference film were sequentially stacked.

Example 2 to Example 3

A polarizing plate was manufactured in the same manner as in Example 1, except that the first phase difference film and the second phase difference film were changed as shown in Table 1 below.

Comparative example 1 to Comparative example 6

A polarizing plate was manufactured in the same manner as in Example 1, except that the first phase difference film and the second phase difference film were changed as shown in Table 2 below.

The angle formed by the absorption axis of the polarizer in the polarizing film and the fast axis of the first phase difference film was -45°.

Example 1 Example 2 Example 3 Second phase difference film Rth(nm) -110.4 -120.2 -127.6 Re(nm) 0.24 0.2 0.3 NZ -760.4 -705.4 -593.7 Liquid crystal Nematic Nematic Nematic manufacturer DNP DNP DNP First phase difference film Rth(nm) 74.3 74.3 74.3 Re(nm) 139.0 139.0 139.0 NZ 1.0 1.0 1.0 Liquid crystal Nematic Nematic Nematic Wavelength dispersion
(Re _{450 /} Re ₅₅₀ ) 0.84 0.84 0.84 Product Name/ Manufacturer RMM1640/Merck RMM1640/Merck RMM1640/Merck

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Second phase difference
film Rth(nm) -59.4 -70.1 -79.9 -87.4 -99.4 -198.0 Re(nm) 0.1 0.3 0.1 0.2 0.2 0.1 NZ -760.4 -780.7 -724.5 -597.8 -760.6 -792.1 Liquid crystal Nematic Nematic Nematic Nematic Nematic Nematic manufacturer DNP DNP DNP DNP DNP DNP First phase difference film Rth(nm) 74.3 74.3 74.3 74.3 74.3 74.3 Re(nm) 139.0 139.0 139.0 139.0 139.0 139.0 NZ 1.0 1.0 1.0 1.0 1.0 1.0 Liquid crystal Nematic Nematic Nematic Nematic Nematic Nematic Wavelength dispersion
(Re _{450 /} Re ₅₅₀ ) 0.84 0.84 0.84 0.84 0.84 0.84 Product Name/ Manufacturer RMM1640/Merck RMM1640/Merck RMM1640/Merck RMM1640/Merck RMM1641/Merck RMM1641/Merck

The following physical properties were evaluated for the laminated retardation film and the polarizing plate prepared in Examples and Comparative Examples, and the results are shown in Tables 3 and 4 below.

Property evaluation

(1) Retardation of laminated retardation film: The laminated retardation films prepared in Examples and Comparative Examples were measured using an Axoscan apparatus at a wavelength of 550 nm.

(2) Front reflectance and side reflectance: A specimen was prepared by attaching an adhesive layer to the lower surface of the second phase difference film of the polarizing plates prepared in Examples and Comparative Examples, and laminating the polarizing plate on the reflective panel via the adhesive layer. The front reflectance (0°, 5°) was measured using a spectrophotometer CM-3600d (Konica Minolta) under conditions of a light source D65 and a light receiving unit 10°. The side reflectance (0°, 60°) was measured using DMS (Instrument Systems).

(3) Color shift (Δa*b*): It measured using DMS (Instrument Systems) using the polarizing plate manufactured by the Example and the comparative example. Color shifts were calculated by measuring reflectance and color coordinates from 0.05° to 60°. The lower the color shift value, the less the difference between the reflection color observed from the front and the reflection color from the side.

(4) Front color: The polarizing plates prepared in Examples and Comparative Examples were used to measure using DMS (Instrument Systems, Inc.). The lower the front color value, the closer the neutral color to the neutral black, indicating that the front color is improved.

Example 1 Example 2 Example 3 NZ of laminated retardation film 0.167 0.057 -0.025 Rth(nm) of laminated retardation film -48.24 -52.14 -73.30 Re(nm) of laminated retardation film 139.1 139.5 139.4 Side reflectance (%) 0.9 0.87 0.82 Front reflectance (%) 0.49 0.48 0.47 Reflectance difference (%) 0.41 0.39 0.35 Color shift 2.954 2.439 2.091 Frontal color 0.8 0.41 0.09

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 NZ of laminated retardation film 0.56 0.51 0.352 0.304 0.223 -0.608 Rth(nm) of laminated retardation film -6.17 -10 -21.46 -30 -40 -141.8 Re(nm) of laminated retardation film 139.3 139.2 139.2 139.4 139.7 139.0 Side reflectance (%) 1.1 1.07 1.03 1.02 0.93 0.92 Front reflectance (%) 0.51 0.5 0.51 0.51 0.5 0.51 Reflectance difference (%) 0.59 0.57 0.52 0.51 0.43 0.41 Color shift 5.24 4.709 4.433 3.522 3.701 5.47 Frontal color 2.344 2.018 1.86 1.11 0.80 2.14

As shown in Table 3, the polarizing plate of the present invention can lower the front reflectance and the side reflectance, and lower the difference between the front reflectance and the side reflectance to reduce the difference between the uniform reflection color and the side-to-front reflectance across the screen of the display device. Can be lowered. In addition, the polarizing plate of the present invention can improve color shift and improve color sense on the entire screen of the display device by improving front color.

On the other hand, Comparative Examples 1 to 4, in which the NZ of the laminated retardation film was greater than 0.2, had a high reflectance difference between the side and the front and a poor color feeling at the side and the front. In Comparative Example 5 in which the NZ of the laminated retardation film was greater than 0.2, the side color shift was not good. In Comparative Example 6 in which the NZ of the laminated retardation film was less than -0.2, the color shift at the side was not good, and the color at the front was not good.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (14)

A polarizing plate for a light emitting display device comprising a polarizing film and a laminated retardation film formed on one surface of the polarizing film,
The laminated retardation film includes a second phase difference film and a first phase difference film sequentially stacked from the polarizing film,
The laminated retardation film has a degree of biaxiality (NZ) of Equation 1 below at a wavelength of 550 nm of -0.2 to 0.2,
[Equation 1]
NZ = (nx-nz)/(nx-ny)
(In the above formula 1, nx, ny, nz are refractive indices in the x-axis, y-axis, and z-axis directions of the laminated retardation film at a wavelength of 550 nm, respectively.
The second phase difference film is a positive C plate, and the first phase difference film is a reverse wavelength dispersive positive A plate,
The second phase difference film has a retardation (Rth) in the thickness direction of Equation 2 below at a wavelength of 550 nm is -190 nm to -110 nm,
[Equation 2]
Rth = ((nx + ny)/2-nz) xd
(In the formula 2, nx, ny, nz are the refractive index in the x-axis, y-axis, and z-axis directions of the second retardation film at a wavelength of 550 nm, d is the thickness of the second retardation film (unit: nm)),
The first phase difference film has a thickness direction retardation (Rth) of the following equation 3 at a wavelength of 550nm is 60nm to 80nm,
[Equation 3]
Rth = ((nx + ny)/2-nz) xd
(In the above formula 3, nx, ny, nz is the refractive index in the x-axis, y-axis and z-axis directions of the first retardation film at a wavelength of 550 nm, d is the thickness of the first retardation film (unit: nm)),
The first phase difference film has a degree of biaxiality (NZ) of the following formula 4 at a wavelength of 550 nm is 0.9 to 1.3, a polarizing plate for a light emitting display device:
[Equation 4]
NZ = (nx-nz)/(nx-ny)
(In the above formula 4, nx, ny, nz are refractive indexes in the x-axis, y-axis, and z-axis directions of the first retardation film at a wavelength of 550 nm, respectively).
The polarizing plate of claim 1, wherein the laminated retardation film has an in-plane retardation (Re) of 130 nm to 150 nm at a wavelength of 550 nm.
The polarizing plate of claim 1, wherein the laminated retardation film has a thickness retardation (Rth) of -80 nm to -45 nm at a wavelength of 550 nm.
delete The polarizing plate of claim 1, wherein the second phase difference film is a liquid crystal film.
The polarizing plate of claim 5, wherein the liquid crystal film includes at least one liquid crystal layer of nematic liquid crystal or discotic liquid crystal.
delete delete The polarizing plate of claim 1, wherein the first phase difference film is a liquid crystal film.
The polarizing plate of claim 9, wherein the liquid crystal film includes at least one liquid crystal layer of nematic liquid crystal or discotic liquid crystal.
The polarizing plate of claim 1, wherein the second phase difference film is a nematic liquid crystal film, and the first phase difference film is a nematic liquid crystal film.
The light emission of claim 1, wherein the first phase difference film has a ratio (Re(450)/Re(550)) of an in-plane retardation value at a wavelength of 450 nm to an in-plane retardation value at a wavelength of 550 nm. Polarizer for display devices.
The polarizing plate of claim 1, wherein an angle formed between a fast axis of the first phase difference film and an absorption axis of the phase polarizing film is −90° to 0°.
A light-emitting display device comprising the polarizing plate for a light-emitting display device of any one of claims 1 to 3, 5, 6 or 9 to 13.

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