KR102620956B1 - Polarizing plate and optical display apparatus comprising the same - Google Patents

Abstract

polarizer; and a first retardation layer and a second retardation layer sequentially stacked on the lower surface of the polarizer, wherein the first retardation layer has constant wavelength dispersion and has a refractive index relationship of Equation 5, and the second retardation layer It has constant wavelength dispersion and has a refractive index relationship of Equation 8, and the first phase difference layer has a slow axis direction of the first phase difference layer in an inclined direction compared to the width direction of the laminate of the first phase difference layer and the second phase difference layer. is oriented, and the polarizer has a polarization degree of 99% or more and a single light transmittance (Ts) of 44% or more. A polarizing plate and an optical display device including the same are provided.

Description

Polarizing plate and optical display device including the same {POLARIZING PLATE AND OPTICAL DISPLAY APPARATUS COMPRISING THE SAME}

The present invention relates to a polarizing plate and an optical display device including the same. More specifically, the present invention relates to a polarizer capable of significantly lowering the side reflectance and front reflectance in the entire polar angle (θ) range of 5° to 60°, and an optical display device including the same.

Organic EL panels include a highly reflective metal electrode layer. Therefore, the visibility of the organic EL panel deteriorates due to reflection of external light. This worsening of visibility is being improved by attaching a circular polarizer to the organic EL panel.

Circular polarizers are generally manufactured by laminating a quarter phase plate to a polarizer. Since retardation plates made of COP (cyclic olefin polymer)-based resin have so-called flat wavelength dispersion characteristics in which the retardation value is almost constant without depending on the wavelength of the measurement light, there is a problem in that excellent reflected color is not obtained when applied. In order to improve the shortcomings of the flat wavelength dispersion, a circular polarizer including a retardation film of PC (polycarbonate)-based resin with reverse wavelength dispersion in which the retardation value increases depending on the wavelength of the measurement light has been proposed. However, these circular polarizers greatly improve external light reflection and reflected color in the front direction, but when the panel is viewed from an angle, a color different from the color in the front direction is obtained, causing a color difference problem.

The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2016-0107114, etc.

An object of the present invention is to provide a polarizer that significantly reduces side reflectance.

Another object of the present invention is to provide a polarizing plate that has a thinning effect and a process improvement effect.

One aspect of the present invention is a polarizer.

1.Polarizer is a polarizer; And a first phase difference layer and a second phase difference layer sequentially stacked on the lower surface of the polarizer,

The first phase difference layer has constant wavelength dispersion and has a refractive index relationship of the following equation 5:

[Equation 5]

nx > ny ≒ nz

(In Equation 5, nx, ny, and nz are the refractive indices of the first phase difference layer in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm),

The second phase difference layer has constant wavelength dispersion and has a refractive index relationship of the following equation 8:

[Equation 8]

nx ≒ nz > ny

(In Equation 8, nx, ny, and nz are the refractive indices of the second phase difference layer in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm),

The first phase difference layer has a slow axis direction of the first phase difference layer oriented in an inclined direction relative to the transverse direction (TD) of the laminate of the first phase difference layer and the second phase difference layer, and the first phase difference layer The laminate of the layer and the second phase difference layer has reverse wavelength dispersion, and the polarizer has a polarization degree of 99% or more and a single light transmittance (Ts) of 44% or more.

In 2.1, the laminate of the first phase difference layer and the second phase difference layer may be a one-sheet type film.

In 3.1-2, the laminate of the first phase difference layer and the second phase difference layer may have an in-plane retardation (Re) of 140 nm to 200 nm at a wavelength of 550 nm.

In 4.1-3, the laminate of the first phase difference layer and the second phase difference layer may satisfy Equation 1 and Equation 2 below:

[Equation 1]

0.8 ≤ Re(450)/Re(550) < 1.0

[Equation 2]

1.0 < Re(650)/Re(550) ≤ 1.2

(In Equations 1 and 2 above, Re (450), Re (550), and Re (650) are the in-plane retardation at the wavelengths of 450 nm, 550 nm, and 650 nm of the laminate of the first phase difference layer and the second phase difference layer, respectively).

In 5.1-4, the slow axis direction of the first phase difference layer may be 70° ± 10° compared to the TD of the laminate of the first phase difference layer and the second phase difference layer.

In 6.1-5, the slow axis direction of the second phase difference layer may be 0° ± 20° (except 0°) compared to the TD of the laminate of the first phase difference layer and the second phase difference layer. .

In 7.1-6, the angle formed by the slow axis direction of the first retardation layer with respect to the absorption axis of the polarizer may be 10° to 30°.

In 8.1-7, the angle formed by the slow axis direction of the second retardation layer with respect to the absorption axis of the polarizer may be 70° to 90°.

In 9.1-8, the first phase difference layer may be a positive A phase difference layer, and the second phase difference layer may be a negative A phase difference layer.

In 10.1-9, the first phase difference layer is a cyclic olefin polymer such as norbornene polymer; Polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyvinyl alcohol; polyvinyl chloride; polyarylsulfone; Polyolefins such as polyethylene and polypropylene; polyarylate; It may include a film containing one or more types of rod-shaped liquid crystal polymers.

11.1-10, the second phase difference layer is a homopolymer of styrene or a styrene derivative, a polystyrene-based polymer including a copolymer between styrene or a styrene derivative and a comonomer, a polyacrylonitrile polymer, a polymethyl methacrylate copolymer, It may include a coating layer containing one or more types of cellulose-based copolymers such as cellulose ester.

12.1-11, the first phase difference layer may have an in-plane retardation of 220 nm to 280 nm at a wavelength of 550 nm, and the second phase difference layer may have an in-plane retardation of 85 nm to 145 nm at a wavelength of 550 nm.

13.1-12, the polarizer may have an orthogonal light transmittance of 0.001% to 0.7%.

14.1-13, the second phase difference layer may be formed directly on the first phase difference layer.

15.1-14, a protective layer may be further laminated on the upper surface of the polarizer.

The optical display device of the present invention includes the polarizing plate of the present invention.

The present invention provides a polarizer that significantly reduces side reflectance.

The present invention provides a polarizing plate having a thinning effect and an improvement in processability.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.
Figure 2 shows the slow axis direction of each of the first phase difference layer and the second phase difference layer in Figure 1.
FIG. 3 shows the slow axis directions of each of the first phase difference layer and the second phase difference layer with respect to the absorption axis of the polarizer in FIG. 1.

Hereinafter, embodiments of the present application will be described in more detail with reference to the attached drawings. However, the technology disclosed in this application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced here are provided to ensure that the disclosed content is thorough and complete and that the spirit of the present application can be sufficiently conveyed to those skilled in the art. In order to clearly express the components of each device in the drawings, the sizes of the components, such as the width and thickness, are shown somewhat enlarged. In the present invention, the sizes of the components, such as the width and thickness, are limited to the scope of the present invention. It doesn't work. In a plurality of drawings, like symbols refer to substantially the same components.

In this specification, “upper” and “lower” are defined based on the drawings, and depending on the viewing perspective, “upper” may be changed to “lower” and “lower” may be changed to “upper”, and “on” or What is referred to as “on” may include not only directly above but also cases where other structures are interposed. On the other hand, what is referred to as “directly on” or “directly on” or “directly formed” indicates that there is no intervening other structure such as an intermediate.

In this specification, “in-plane retardation (Re)” is expressed by the following formula A, “thickness direction retardation (Rth)” is expressed by the following formula B, and “biaxiality degree (NZ)” is expressed by the following formula C:

[Formula A]

Re = (nx - ny) x d

[Formula B]

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

[Formula C]

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

(In the above formulas A to C, nx, ny, and nz are the refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element. (Unit: nm).

In the above formulas A to C, “optical element” means a first phase difference layer, a second phase difference layer, or a laminate of the first phase difference layer and the second phase difference layer. In Formulas A to C, “measurement wavelength” may mean a wavelength of 450 nm, 550 nm, or 650 nm.

As used herein, “(meth)acrylic” means acrylic and/or methacrylic.

In this specification, when describing a numerical range, “X to Y” means more than X and less than Y (X≤ and ≤Y).

In this specification, when describing a numerical range, “X ± Y” means “X + Y” to “X - Y”.

The inventor of the present invention stacks a laminate of a first phase difference layer and a second phase difference layer, in which a first phase difference layer described in detail below and a second phase difference layer described in detail below, is formed on the lower surface of a polarizer, and the polarization degree of the polarizer and the single light By setting the transmittance to a specific range, it was confirmed that when the polarizing plate was applied to an optical display device, the side reflectance was significantly lowered, especially in the entire polar angle (θ) range of 5° to 60°, and the present invention was completed. The inventor of the present invention was able to significantly lower the side reflectance by going further than adjusting the phase difference of the retardation layer and controlling the polarization degree and single light transmittance of the polarizer together.

Hereinafter, a polarizing plate of an embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3.

Referring to FIG. 1, the polarizer includes a protective layer 400, a polarizer 300, a first phase difference layer 110, and a second phase difference layer 210. The protective layer 400 is laminated on the upper surface of the polarizer 300, and the first phase difference layer 110 and the second phase difference layer 210 are sequentially laminated on the lower surface of the polarizer 300. The first phase difference layer 110 and the second phase difference layer 210 are stacked without an adhesive layer (or adhesive layer). Through this, the polarizer can achieve a thinning effect.

[Laminate of first phase difference layer and second phase difference layer]

The laminate of the first phase difference layer 110 and the second phase difference layer 210 exhibits wavelength dispersion in which the in-plane phase difference Re decreases from a long wavelength to a short wavelength. That is, the laminate of the first phase difference layer and the second phase difference layer exhibits reverse wavelength dispersion. Through this, the polarizer can improve screen quality when applied to an optical display device. Specifically, the laminate of the first phase difference layer and the second phase difference layer may satisfy Equation 1 and Equation 2 below:

[Equation 1]

0.8 ≤ Re(450)/Re(550) < 1.0

[Equation 2]

1.0 < Re(650)/Re(550) ≤ 1.2

(In Equations 1 and 2 above, Re (450), Re (550), and Re (650) are the in-plane retardation at the wavelengths of 450 nm, 550 nm, and 650 nm of the laminate of the first phase difference layer and the second phase difference layer, respectively).

For example, the laminate of the first phase difference layer and the second phase difference layer may have Re(450)/Re(550) of 0.8 to 0.99, specifically 0.81 to 0.95. The laminate of the first phase difference layer and the second phase difference layer may have Re(650)/Re(550) greater than 1.0 but less than 1.2, 1.01 to 1.15, specifically 1.04 to 1.13. In the above range, screen quality can be improved and side reflectance can be significantly lowered.

In one embodiment, the laminate of the first phase difference layer and the second phase difference layer may have an in-plane phase difference of 140 nm to 200 nm, specifically 140 nm to 195 nm, more specifically 140 nm to 190 nm, and more specifically 150 nm to 190 nm at a wavelength of 550 nm. there is. Within the above range, the side reflectance can be lowered.

In one embodiment, the laminate of the first phase difference layer and the second phase difference layer may have an in-plane phase difference of 130 nm to 190 nm, specifically 135 nm to 185 nm, and more specifically 140 nm to 180 nm at a wavelength of 450 nm. In the above range, an ideal circular polarization effect can be expected by reaching the above-mentioned wavelength dispersion, and there can be an effect of preventing the display panel from appearing blue. In one embodiment, the laminate of the first phase difference layer and the second phase difference layer may have an in-plane phase difference of 150 nm to 210 nm, specifically 155 nm to 205 nm, and more specifically 160 nm to 200 nm at a wavelength of 650 nm. In the above range, the above-mentioned wavelength dispersion can be reached and there can be an effect of preventing the display panel from appearing red.

The laminate of the first phase difference layer and the second phase difference layer may have a thickness of more than 0 μm and 70 μm or less, specifically 5 μm to 60 μm, and more specifically 10 μm to 60 μm. Within the above range, it can be used in a polarizing plate.

The second phase difference layer is formed directly on the first phase difference layer. The term “directly formed” means that no adhesive layer, adhesive layer, or adhesive layer is formed on the second phase difference layer and the first phase difference layer. The second phase difference layer is formed by applying the composition for the second phase difference layer to the first phase difference layer, drying and/or curing it, and then stretching it. Therefore, the laminate of the first phase difference layer and the second phase difference layer is a single-layer film. Through this, the polarizing plate of the present invention enables roll-to-roll lamination when the laminate of the first retardation layer and the second retardation layer is adhered to the polarizer, thereby improving processability and improving yield by reducing defects. Although the first phase difference layer and the second phase difference layer have different phase differences, by being formed directly, the effect of thinning the polarizer and improving processability is obtained.

Hereinafter, the first phase difference layer and the second phase difference layer will be described.

[First phase difference layer]

The first phase difference layer 110 exhibits wavelength dispersion in which the in-plane phase difference increases from a long wavelength to a short wavelength. That is, the first phase difference layer exhibits constant wavelength dispersion. In this way, in the polarizing plate, a first retardation layer having constant wavelength dispersion is formed on the lower surface of the polarizer, and then a second retardation layer having constant wavelength dispersion is laminated on the lower surface of the first retardation layer. Through this, the polarizer can improve screen quality when applied to an optical display device.

Specifically, the first phase difference layer may satisfy Equation 3 and Equation 4 below:

[Equation 3]

1.0 < Re(450)/Re(550) ≤ 1.1

[Equation 4]

0.9 ≤ Re(650)/Re(550) < 1.0

(In Equations 3 and 4 above, Re(450), Re(550), and Re(650) are the in-plane retardation at the wavelengths of 450nm, 550nm, and 650nm, respectively, of the first phase difference layer).

In one embodiment, the first phase difference layer may have Re(450)/Re(550) greater than 1.0 and less than or equal to 1.05. In one embodiment, the first phase difference layer may have Re(650)/Re(550) of 0.95 or more and less than 1.0. In the above range, the effect of reducing front and side reflectance can be excellent.

In one embodiment, the first phase difference layer may have an in-plane retardation of 220 nm to 280 nm, specifically 225 nm to 275 nm, and more specifically 230 nm to 270 nm at a wavelength of 550 nm. Within the above range, the side reflectance can be lowered.

In one embodiment, the first phase difference layer may have an in-plane retardation of 220 nm to 280 nm, specifically 225 nm to 275 nm, and more specifically 230 nm to 270 nm at a wavelength of 450 nm. In the above range, the above-mentioned wavelength dispersion can be reached, and the front and side reflectances can be lowered. In one embodiment, the first phase difference layer may have an in-plane retardation of 220 nm to 280 nm, specifically 225 nm to 275 nm, and more specifically 230 nm to 270 nm at a wavelength of 650 nm. In the above range, the above-mentioned wavelength dispersion can be reached, and the front and side reflectances can be lowered.

The first phase difference layer has a refractive index relationship of the following equation 5: Through this, the side reflectance reduction effect of the present invention can be improved:

[Equation 5]

nx > ny ≒ nz

(In Equation 5, nx, ny, and nz are the refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the first phase difference layer, respectively, at a wavelength of 550 nm).

In one embodiment, the first retardation layer is a positive A retardation layer. Through this, the side reflectance reduction effect of the present invention can be improved.

The first phase difference layer includes a film formed of a composition containing a resin with positive intrinsic birefringence. Therefore, it is possible to easily manufacture a first phase difference layer in which the refractive index in the stretching direction is greater than the refractive index perpendicular to the stretching direction.

Resins with positive intrinsic birefringence include polymers with positive intrinsic birefringence. Polymers with positive intrinsic birefringence include, for example, cyclic olefin polymers such as norbornene polymers; Polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyvinyl alcohol; polyvinyl chloride; polyarylsulfone; Polyolefins such as polyethylene and polypropylene; polyarylate; It may contain one or more types of rod-shaped liquid crystal polymers. Specifically, polycarbonate with excellent retardation properties and elongation at low temperatures, polyolefin-based and cyclic olefin-based copolymers with excellent mechanical properties, heat resistance, transparency, and dimensional stability are preferred. Polymers with positive intrinsic birefringence may be included alone or in combination of two or more types.

The first phase difference layer may further include common additives in addition to the resin having positive intrinsic birefringence. For example, additives may include, but are not limited to, pigments, anti-coloring agents such as dyes, heat stabilizers, light stabilizers, UV absorbers, antistatic agents, antioxidants, particulates, surfactants, etc.

The slow axis direction of the first phase difference layer is oriented in an inclined direction with respect to the transverse direction (TD) of the laminate of the first phase difference layer and the second phase difference layer. The “inclined direction” refers to a direction within the plane of the first phase difference layer, which is neither parallel nor perpendicular to the width direction of the laminate of the first phase difference layer and the second phase difference layer. Since the slow axis direction of the first phase difference layer is oriented in an oblique direction relative to the TD of the laminate of the first phase difference layer and the second phase difference layer, a roll-to-roll method of lamination with a polarizer is possible and the yield may not be reduced. .

In one embodiment, referring to FIG. 2, the slow axis direction (SA ₁₁₀ ) of the first phase difference layer 110 is 70° compared to the TD of the laminate of the first phase difference layer 110 and the second phase difference layer 210. It may be ± 10°, specifically 70° ± 5°, and more specifically 70° ± 3°. In this range, there may be a frontal and side reflection reduction effect.

The first phase difference layer 110 may have a thickness of 5㎛ to 100㎛, specifically 5㎛ to 60㎛. Within the above range, it can be used in a polarizing plate.

The first phase difference layer can be manufactured by producing an unstretched film of a composition containing the above-mentioned positive intrinsic birefringence resin by melt molding, injection molding, or press molding, and stretching the unstretched film in an oblique direction. The stretch ratio may be 1.1 times or more and 4.0 times or less, specifically 1.3 times or more and 3.0 times or less. Within the above range, the slow axis direction of the first phase difference layer can be controlled, and the refractive index in the stretching direction can be increased. The stretching temperature may be a temperature higher than the glass transition temperature (Tg) of the unstretched film + 2°C or higher and lower than Tg+30°C. The stretching direction may be smaller than the angle formed by the slow axis direction of the first retardation layer compared to the TD of the above-described laminate of the first and second retardation layers compared to the width direction of the unstretched film. For example, the stretching direction may be greater than 15° but less than 50°, specifically, greater than 17° and less than 48° compared to the TD of the unstretched film.

The first phase difference layer may be included in the polarizing plate as the first phase difference layer itself, but the adhesion between the first phase difference layer and the second phase difference layer can be increased by further forming a primer layer on the first phase difference layer. The primer layer may include, but is not limited to, one or more of acrylic resin, urethane resin, acrylic urethane resin, ester resin, and ethylene imine resin.

[Second phase difference layer]

The second phase difference layer 210 exhibits wavelength dispersion in which the in-plane phase difference increases from a long wavelength to a short wavelength. That is, the second phase difference layer exhibits constant wavelength dispersion. Through this, the polarizer can improve screen quality when applied to an optical display device. Specifically, the second phase difference layer can satisfy Equation 6 and Equation 7 below:

[Equation 6]

1.0 < Re(450)/Re(550) ≤ 1.2

[Equation 7]

0.9 ≤ Re(650)/Re(550) < 1.0

(In Equations 6 and 7 above, Re(450), Re(550), and Re(650) are the in-plane retardation at the wavelengths of 450nm, 550nm, and 650nm, respectively, of the second phase difference layer).

In one embodiment, the second phase difference layer may have Re(450)/Re(550) of 1.05 to 1.15, more specifically 1.1 to 1.15. In one embodiment, the second phase difference layer may have Re(650)/Re(550) greater than 0.9 and less than or equal to 0.95. In the above range, the effect of reducing front and side reflectance can be excellent.

In one embodiment, the second phase difference layer may have an in-plane retardation of 85 nm to 145 nm, specifically 90 nm to 140 nm, and more specifically 95 nm to 135 nm at a wavelength of 550 nm. Within the above range, front and side reflectance can be significantly lowered.

In one embodiment, the second phase difference layer may have an in-plane retardation of 100 nm to 160 nm, specifically 105 nm to 155 nm, and more specifically 110 nm to 150 nm at a wavelength of 450 nm. In the above range, the above-mentioned wavelength dispersion can be reached, and there can be an effect of reducing front and side reflectance. In one embodiment, the second phase difference layer may have an in-plane retardation of 80 nm to 140 nm, specifically 85 nm to 135 nm, and more specifically 90 nm to 130 nm at a wavelength of 650 nm. In the above range, the above-mentioned wavelength dispersion can be reached, and there can be an effect of reducing front and side reflectance.

The second phase difference layer has a refractive index relationship of the following equation 8: Through this, the side reflectance reduction effect of the present invention can be improved:

[Equation 8]

nx ≒ nz > ny

(In Equation 8 above, nx, ny, and nz are the refractive indices of the second phase difference layer in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm).

In one embodiment, the second retardation layer is a negative A retardation layer. Through this, the side reflectance reduction effect of the present invention can be improved.

The second phase difference layer is formed of a composition containing a resin with negative intrinsic birefringence.

Resins with negative intrinsic birefringence include polymers with negative intrinsic birefringence. Polymers with a negative intrinsic birefringence include, for example, homopolymers of styrene or styrene derivatives, polystyrene-based polymers including copolymers between styrene or styrene derivatives and comonomers, polyacrylonitrile polymers, polymethylmethacrylate copolymers, cellulose esters. It may include one or more types of cellulose-based copolymers, but is not limited thereto. The comonomer may include one or more of acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene. Specifically, preferably, the second phase difference layer may include one or more of a polystyrene-based polymer and a cellulose-based copolymer, and more preferably, a polystyrene-based polymer.

The second phase difference layer may further include common additives in addition to the resin with negative intrinsic birefringence. For example, additives may include, but are not limited to, plasticizers, pigments, anti-coloring agents such as dyes, heat stabilizers, light stabilizers, UV absorbers, antistatic agents, antioxidants, particulates, surfactants, etc.

The slow axis direction of the second phase difference layer is oriented in an inclined direction relative to the transverse direction (TD) of the laminate of the first phase difference layer and the second phase difference layer. The “inclined direction” refers to a direction within the plane of the second phase difference layer, which is neither parallel nor perpendicular to the width direction of the laminate of the first phase difference layer and the second phase difference layer. Since the slow axis direction of the second phase difference layer is oriented in the oblique direction compared to the width direction of the laminate of the first phase difference layer and the second phase difference layer, a roll-to-roll method of lamination with a polarizer is possible and the yield is not reduced. there is.

In one embodiment, referring to FIG. 2, the slow axis direction (SA 210 ) of the second phase difference layer 210 relative to the TD of the laminate of the first phase difference layer 110 and the second phase difference layer ₂₁₀ is 0°. ± 20° (but excluding 0°), specifically 0° ± 10° (but excluding 0°), and more specifically 0° ± 5° (but excluding 0°). there is. In the above range, there may be an effect of improving frontal reflectance.

The second phase difference layer may have a thickness direction retardation of -110 nm to -50 nm, specifically -105 nm to -60 nm, and more specifically -100 nm to -70 nm at a wavelength of 550 nm. Within the above range, there may be an effect of improving front reflectance and side reflectance.

The second phase difference layer may have a degree of biaxiality of -1.0 to 0.5 at a wavelength of 550 nm. Within the above range, there may be an effect of improving front reflectance and side reflectance.

The second phase difference layer may have a thickness of 2㎛ to 15㎛, specifically 3㎛ to 10㎛. Within the above range, it can be used in a polarizing plate.

The second phase difference layer is a coating layer formed of a composition containing a resin with negative intrinsic birefringence.

A laminate of a first phase difference layer and a second phase difference layer can be manufactured by coating the first phase difference layer with a composition for the second phase difference layer, drying it, and then simultaneously stretching it. Through the stretching, the slow axis direction of the first phase difference layer is adjusted, the slow axis direction of the second phase difference layer appears, and the phase difference targeted by the first phase difference layer and the second phase difference layer can be realized.

Specifically, the stretching may be 0° ± 20°, specifically 0° ± 15°, and more specifically 5° ± 15° with respect to the TD of the first phase difference layer and the coating layer. Most preferably, it may be stretched at 90° with respect to the TD of the first phase difference layer and the coating layer, that is, in the longitudinal direction. In this case, the slow axis directions of the first phase difference layer and the second phase difference layer can be easily controlled. The stretching ratio may be 1.1 to 2.0 times, specifically 1.2 to 1.8 times.

[Polarizer]

The polarizer 300 is laminated on the upper surface of the first phase difference layer and can linearly polarize external light or light incident from the first phase difference layer, thereby lowering the reflectance from the side.

The polarizer 300 may have a polarization degree of 99% or more and a single light transmittance (Ts) of 44% or more. The polarizer satisfies the polarization degree and single light transmittance simultaneously, so that when laminated on the above-described laminate of the first and second retardation layers, the side reflectance can be significantly lowered, especially in the entire polar angle (θ) range of 5° to 60°. there is. The “single light transmittance” refers to the single light transmittance (Ts) measured in the visible light region, for example, at a wavelength of 400 nm to 700 nm, and can be measured by a common method known to those skilled in the art.

The “polarization degree” can be measured by a common method known to those skilled in the art. Specifically, the degree of polarization may be 99% to 99.9999%, and the light transmittance may be 44% to 50%.

The polarizer 300 may have an orthogonal light transmittance (Tc) of 0.001% to 0.7%, specifically 0.01% to 0.2%, and more specifically 0.05% to 0.2% at a wavelength of 380 nm to 780 nm. In the above range, there may be an anti-reflection effect on the sides, especially in the entire polar angle (θ) range of 5° to 60°.

The polarizer 300 is laminated roll-to-roll on a laminate of the first retardation layer and the second retardation layer. Accordingly, the laminate of the first retardation layer and the second retardation layer functions as a lower protective film of the polarizer, so there is no need to laminate a separate protective film on the lower surface of the polarizer, making it possible to thin the polarizer.

Referring to FIG. 3, the slow axis direction (SA 110 ) of the first phase difference layer ₁₁₀ and the slow axis direction (SA 210 ) of the second phase difference layer ₂₁₀ intersect each other, and the absorption axis of the polarizer 300 ( The angle formed by the slow axis direction (SA ₁₁₀ ) of the first phase difference layer 110 with respect to A ₃₀₀ ) is 10° to 30°, specifically 15° to 30°, and the absorption axis (A ₃₀₀ ) of the polarizer 300 The angle formed by the slow axis direction (SA ₂₁₀ ) of the second phase difference layer 210 with respect to may be 70° to 90°, specifically 80° to 90°, and more specifically 80° to 90°. In the above range, there may be a frontal reflectance reduction effect.

The absorption axis of the polarizer is the MD (machine direction) of the polarizer, which may be the stretching direction when manufacturing the polarizer.

The polarizer 300 may have a thickness of 5㎛ to 40㎛. Within the above range, it can be used in a polarizing plate.

The polarizer 300 may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film.

In one embodiment, the polarizer may be manufactured by dyeing, stretching, crosslinking, and color correction processes of a polyvinyl alcohol-based film. A polarizer having both the above-described polarization degree and light transmittance can be achieved by appropriately changing the conditions in the above-described dyeing, stretching, crosslinking, and color correction processes.

Although not shown in FIG. 1, an adhesive layer, an adhesive layer, a point adhesive layer, or a protective layer described in detail below may be further formed between the polarizer 300 and the first retardation layer 110.

[Protective layer]

The protective layer 400 may be laminated on the upper surface of the polarizer to protect the polarizer. The protective layer can protect the polarizing film to increase the reliability of the polarizing plate and increase the mechanical strength of the polarizing plate.

Protective layer 400 may include one or more of an optically transparent protective film or protective coating layer. The protective film includes a cellulose ester-based resin including triacetylcellulose (TAC), a cyclic polyolefin-based resin including amorphous cyclic polyolefin (COP), a polycarbonate-based resin, and polyethylene terephthalate (PET). Poly(meth)acrylate-based resins, including polyester-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins, etc. It may include, but is not limited to, a film formed of one or more of resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin. The protective coating layer may be formed of an active energy ray curable resin composition containing an active energy ray curable compound and a polymerization initiator. The active energy ray-curable compound may include one or more of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin.

Although not shown in FIG. 1, a functional coating layer may be additionally formed on the upper surface of the protective layer. The functional coating layer may include, but is not limited to, one or more of a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low-reflection layer, and an ultra-low-reflection layer.

Although not shown in FIG. 1, an adhesive layer is further formed on the lower surface of the second retardation layer, so that the polarizing plate can be laminated on the optical display device.

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

The polarizing plate includes a protective layer, a polarizer, a first phase difference layer, and a second phase difference layer. A protective layer is laminated on the upper surface of the polarizer, and a first phase difference layer and a second phase difference layer are sequentially laminated on the lower surface of the polarizer. The polarizer of FIG. 1 is substantially the same as the polarizer of an embodiment of the present invention, except that the first and second retardation layers described in detail below are laminated instead of the first and second retardation layers.

The first phase difference layer and the second phase difference layer are the same as those described in FIG. 1 except for the details described below.

In one embodiment, the slow axis direction of the first phase difference layer relative to the TD of the laminate of the first phase difference layer and the second phase difference layer 220 is 22.5° ± 15°, specifically 22.5° ± 10°, and more specifically 22.5°. ° can be ± 5°. Within the above range, there may be an effect of increasing circular polarization.

In one embodiment, the slow axis direction of the second phase difference layer relative to the TD of the laminate of the first phase difference layer and the second phase difference layer is 90° ± 25°, specifically 90° ± 20°, and more specifically 90° ± 10°. It can be °. Within the above range, there may be an effect of increasing circular polarization.

Hereinafter, the optical display device of the present invention will be described.

The optical display device of the present invention may include one or more of the polarizers of the present invention. In one embodiment, the optical display device may include a liquid crystal display device, a light emitting display device, and preferably a light emitting device display device. The liquid crystal display device may include a liquid crystal display device having a liquid crystal for IPS (In Place Switching). The light emitting device display device includes an organic or inorganic light emitting device, and includes light emitting materials such as, for example, LED (light emitting diode), OLED (organic light emitting diode), QLED (quantum dot light emitting diode), and phosphor. It may mean a light emitting device.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example One

A polyvinyl alcohol film was stretched 3 times at 60°C, iodine was adsorbed, and then stretched 2.5 times in an aqueous boric acid solution at 40°C to prepare a polarizer (thickness: 12㎛). The single light transmittance and orthogonal light transmittance of the polarizer were measured at a wavelength of 380 nm to 780 nm using a spectrophotometer V-7100 from JASCO. The polarization degree of the polarizer was measured using JASCO's V-7100.

A triacetylcellulose (TAC) film (KA25-HC, Konica Minolta Opto, Inc., thickness: 32㎛) with a hard coating layer formed on the upper surface of the polarizer was attached.

On the lower surface of the polarizer, the first phase difference layer [constant wavelength dispersion, +A plate, polyolefin-based, Re (450) = 253 nm, Re (550) = 251 nm, Re (650) = 250 nm] and the second phase difference layer [ Forward wavelength dispersion, -A plate, polystyrene-based, Re (450) = 129 nm, Re (550) = 116 nm, Re (650) = 110 nm] is a one-sheet type film laminated on each other without an adhesive layer [reverse wavelength dispersion, Triacetylcellulose (TAC) film with a hard coating layer formed by adhering [Re(450)/Re(550)= 0.91, Re(650)/Re(550)= 1.06] - Polarizer - 1st phase difference layer - 2nd phase difference A polarizing plate in which the layers were sequentially stacked was manufactured.

The one-sheet type film is manufactured by obliquely stretching a resin containing a polyolefin-based copolymer at a predetermined stretching ratio and coating a polystyrene-based copolymer on one side of the film of the obliquely stretched polyolefin-based copolymer, and manufacturing the laminate. This is a film manufactured by stretching again to a predetermined stretching ratio.

Example 2 to Example 3

In Example 1, a polarizer was manufactured in the same manner as in Example 1, except that a film having the specifications of Table 1 below was used as the single-sheet film or the polarization degree and light transmittance of the polarizer were changed as shown in Table 1 below. did.

Comparative example One

In Example 2, the single-sheet film was used in the same manner as in Example 2, except that a film having the specifications in Table 1 below was used and a polarizer whose polarization degree was changed to 98.0% and light transmittance to 44.5% was used. A polarizing plate was manufactured.

Comparative example 2

In Example 2, a film having the specifications shown in Table 1 below was used as the single-sheet film, and a polarizer whose polarization degree was changed to 99.0% and light transmittance to 43.5% was used in the same manner as Example 2. A polarizing plate was manufactured.

Table 1 below shows specific specifications of the polarizers of Examples and Comparative Examples.

polarizer Phase contrast laminate orientation angle The angle formed between the absorption axis of the polarizer and the slow axis of the first phase difference layer (°) The angle formed between the absorption axis of the polarizer and the slow axis of the second phase difference layer (°) Polarization
(%) single light
Transmittance
(Ts, %) orthogonal light
Transmittance
(Tc, %) Re(550)
(nm) Example 1 99.5 44.5 0.20 150 70 20 84 Example 2 99.5 44.5 0.20 170 70 20 84 Example 3 99.5 44.5 0.20 190 70 20 84 Comparative Example 1 98.0 44.5 0.35 170 70 20 84 Comparative example 2 99.0 43.5 0.25 170 70 20 84

*Orientation angle: The angle formed by the slow axis direction of the first phase difference layer with the width direction (TD) of the laminate of the first phase difference layer and the second phase difference layer.

The reflectance (unit: %) according to the side angle of the polarizers manufactured in Examples and Comparative Examples was evaluated, and the results are shown in Table 2 below. The reflectance is SCE (specular component excluded) reflectance data measured with a DMS803 (Instrument Systems, Germany) equipment by attaching the polarizing film of Table 1 to the Galaxy S7 panel.

Viewing angle (°) 5 10 20 30 40 50 60 Example 1 0.36 0.36 0.39 0.47 0.60 0.81 0.99 Example 2 0.33 0.34 0.36 0.43 0.57 0.76 0.93 Example 3 0.39 0.39 0.42 0.50 0.65 0.86 1.03 Comparative Example 1 0.48 0.48 0.51 0.58 0.72 0.91 1.06 Comparative example 2 0.45 0.45 0.50 0.56 0.70 0.91 1.06

As shown in Table 2 above, the polarizer of the present invention significantly lowered the side reflectance.

On the other hand, Comparative Example 1, in which the polarization degree of the polarizer was less than 99.0%, had a side reflectance higher than that of the Example, and although not shown in Table 2, a front reflectance was higher than that of the Example. Comparative Example 2, in which the transmittance of the polarizer was less than 44%, also had a higher side reflectance than the Example, and although not shown in Table 2, the front reflectance was also higher than the Example.

Simple modifications or changes to the present invention can be easily implemented 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 (16)

polarizer; And a first phase difference layer and a second phase difference layer sequentially stacked on the lower surface of the polarizer,
The first phase difference layer has constant wavelength dispersion and has a refractive index relationship of the following equation 5:
[Equation 5]
nx > ny ≒ nz
(In Equation 5, nx, ny, and nz are the refractive indices of the first phase difference layer in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm),
The second phase difference layer has constant wavelength dispersion and has a refractive index relationship of the following equation 8:
[Equation 8]
nx ≒ nz> ny
(In Equation 8, nx, ny, and nz are the refractive indices of the second phase difference layer in the slow axis direction, fast axis direction, and thickness direction, respectively, at a wavelength of 550 nm),
The first phase difference layer satisfies Equation 3 below:
[Equation 3]
1.0 < Re(450)/Re(550) ≤ 1.05
(In Equation 3 above, Re (450) and Re (550) are the in-plane retardation at the wavelengths of 450 nm and 550 nm of the first phase difference layer, respectively),
The first phase difference layer has a slow axis direction of the first phase difference layer oriented in an inclined direction relative to the width direction (TD) of the laminate of the first phase difference layer and the second phase difference layer,
The laminate of the first phase difference layer and the second phase difference layer has reverse wavelength dispersion,
The polarizer has a polarization degree of 99% or more, a single light transmittance (Ts) of 44% or more, and an orthogonal light transmittance of 0.001% to 0.7%.
The polarizing plate of claim 1, wherein the laminate of the first retardation layer and the second retardation layer is a one-sheet type film.
The polarizing plate of claim 1, wherein the laminate of the first phase difference layer and the second phase difference layer has an in-plane retardation (Re) of 140 nm to 200 nm at a wavelength of 550 nm.
The polarizing plate of claim 1, wherein the laminate of the first phase difference layer and the second phase difference layer satisfies the following equations 1 and 2:
[Equation 1]
0.8 ≤ Re(450)/Re(550) < 1.0
[Equation 2]
1.0 < Re(650)/Re(550) ≤ 1.2
(In Equations 1 and 2 above, Re (450), Re (550), and Re (650) are the in-plane retardation at the wavelengths of 450 nm, 550 nm, and 650 nm of the laminate of the first phase difference layer and the second phase difference layer, respectively).
The polarizing plate of claim 1, wherein the slow axis direction of the first phase difference layer is 70° ± 10° compared to the TD of the laminate of the first phase difference layer and the second phase difference layer.
The method of claim 5, wherein the slow axis direction of the second phase difference layer is 0° ± 20° (except 0°) compared to the TD of the laminate of the first phase difference layer and the second phase difference layer. , polarizer.
The polarizing plate of claim 1, wherein an angle formed by the slow axis direction of the first retardation layer with respect to the absorption axis of the polarizer is 10° to 30°.
The polarizing plate of claim 1, wherein an angle formed by the slow axis direction of the second retardation layer with respect to the absorption axis of the polarizer is 70° to 90°.
The polarizing plate of claim 1, wherein the first phase difference layer is a positive A phase difference layer, and the second phase difference layer is a negative A phase difference layer.
The method of claim 1, wherein the first phase difference layer is a cyclic olefin polymer such as norbornene polymer; Polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyvinyl alcohol; polyvinyl chloride; polyaryl sulfone; polyolefins such as polyethylene and polypropylene; polyarylate; A polarizer comprising a film containing at least one type of rod-shaped liquid crystal polymer.
The method of claim 1, wherein the second phase difference layer is a homopolymer of styrene or a styrene derivative, a polystyrene-based polymer including a copolymer between styrene or a styrene derivative and a comonomer, a polyacrylonitrile polymer, or a polymethyl methacrylate copolymer. A polarizing plate comprising a coating layer containing at least one type of cellulose-based copolymer such as cellulose ester.
The polarizing plate of claim 1, wherein the first phase difference layer has an in-plane retardation of 220 nm to 280 nm at a wavelength of 550 nm, and the second phase difference layer has an in-plane retardation of 85 nm to 145 nm at a wavelength of 550 nm.
delete The polarizing plate of claim 1, wherein the second retardation layer is formed directly on the first retardation layer.
The polarizing plate of claim 1, wherein a protective layer is further laminated on the upper surface of the polarizer.
An optical display device comprising the polarizer of any one of claims 1 to 12, 14, and 15.