KR102437157B1 - Polarizing Plate - Google Patents

Abstract

This application relates to a polarizing plate. The polarizing plate of the present application has excellent antireflection performance of external light, as well as excellent barrier performance against external environments such as moisture, and can be thinned and rolled. Such a polarizing plate may be applied to an OLED display and may be suitable for improving black visual perception, improving durability, miniaturizing a device, and implementing a rollable device.

Description

Polarizing Plate

This application relates to a polarizing plate.

An organic light emitting device (OLED) panel may reflect external light, such as sunlight and lighting, due to electrode exposure, and visibility and contrast ratio may be lowered by the reflected external light, thereby reducing display quality. In order to block the reflection of external light on the surface in the power-off state and to have a black feeling, as disclosed in Patent Document 1. A circular polarizer in which a linear polarizer and a λ/4 retardation material are combined can be attached to the viewing side of the OLED panel and used.

In addition, rollable OLED displays are continuously being developed. In order to realize a rollable display, a material that can be thinned and bendable is required. In order to protect the OLED device, which is unfavorable to moisture, a glass material with weak moisture permeability may be used as the main material in the OLED panel. In this case, it is difficult to implement a rollable display.

Korean Patent Publication No. 2009-0122138

The present application has excellent antireflection performance of external light, as well as excellent barrier performance against external environments such as moisture, and a polarizing plate that can be thinned and rolled, and improved black visual perception, durability, and device An organic light emitting diode display capable of being miniaturized and a rollable device is provided.

This application relates to a polarizing plate. 1 exemplarily shows the structure of the polarizing plate of the present application. The polarizing plate of the present application may include a polarizer 10 , a retardation layer 20 , and a barrier film 30 in sequence. The retardation layer 20 may have a λ/4 phase delay characteristic. The barrier film 30 may include a base film 300 and a first barrier layer 301 and a second barrier layer 302 laminated on the base film. The moisture permeability of the base film may be 1 g/m ² ·day to 100 g/m ² ·day. The moisture permeability of the first barrier layer and the second barrier layer may be 10 ^-4 g/m ² ·day to 10 ^-6 g/m ² ·day. The retardation layer and the barrier film may be attached to each other via the pressure-sensitive adhesive layer 40 .

Such a polarizing plate may have excellent antireflection performance of external light, excellent barrier performance against an external environment such as moisture, and may have thinning and rolling properties. Hereinafter, the polarizing plate of the present application will be described in detail.

In this specification, the terms polarizer and polarizing plate refer to objects that are distinct from each other. The term polarizer refers to a film, sheet, or device having a polarization function itself, and the term polarizing plate refers to an object including the polarizer and other elements laminated on one or both surfaces of the polarizer. In the above, other elements may include a protective film, a pressure-sensitive adhesive layer, an adhesive layer, a surface treatment layer, a retardation layer, or a barrier film of the polarizer.

The polarizer may be an absorption type polarizer. In the present specification, the absorption type polarizer refers to a device that selectively transmits and absorbs incident light. The polarizer may transmit, for example, light vibrating in one direction from incident light vibrating in multiple directions, and may absorb light vibrating in the other direction.

The polarizer may be a linear polarizer. In the present specification, the linear polarizer means a case in which selectively transmitted light is linearly polarized light vibrating in one direction and selectively absorbed light is linearly polarized light vibrating in a direction orthogonal to the vibration direction of the linearly polarized light.

The polarizer may be a polymer film containing a dichroic material. The dichroic material may be iodine or a dichroic dye. As the polymer film, a polyvinyl alcohol-based film may be used. The dichroic material may be included in the polymer film in an oriented state.

The barrier film may include a base film and a first barrier layer and a second barrier layer laminated on the base film.

The moisture permeability of the base film may be 1 g/m ² ·day to 100 g/m ² ·day. In the present specification, water vapor transmission rate (WVTR) refers to a numerical value indicating the amount of water passing through a corresponding film for a unit area and a unit time. Unless otherwise specified herein, the moisture permeability is a value measured under the conditions of 38° C. temperature and 100% relative humidity. When the moisture permeability of the base film is within the above range, it may be advantageous to improve the barrier performance of the polarizing plate against moisture by increasing the moisture permeation prevention effect.

As the base film, a plastic film may be used for rollable properties. As the plastic film, for example, PA (Polyacrylate); COP (cyclo olefin polymer); PMMA(poly(methyl methacrylate); PC(polycarbonate); PE(polyethylene); PP(polypropylene); PVA(polyvinyl alcohol); DAC(diacetyl cellulose); PES(poly ether sulfone); PEEK(polyetheretherketon); PPS(polyphenylsulfone) ), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate), etc. As a specific example, as the base film, an acrylic film or COP-based film may be used The use of such a base film may be advantageous in terms of exhibiting moisture permeability within the above range.

The base film may exhibit optical isotropy. In one example, the absolute value of the in-plane retardation value and the thickness direction retardation value with respect to a wavelength of 550 nm of the base film may be 10 nm or less, respectively. As will be described later, the polarizing plate may prevent reflection of external light due to the λ/4 phase delay characteristic of the retardation layer. It is advantageous that the base film exhibits optical isotropy so as not to impair such performance.

In the present specification, the in-plane retardation (Rin) value and the thickness direction retardation (Rth) value of the base film, the retardation layer, the liquid crystal layer, the retardation film, etc. may be calculated by the following Equations 1 and 2, respectively.

[Formula 1]

Rin = d × (nx - ny)

[Equation 2]

Rth = d × (nz - ny)

In Equations 1 and 2, nx, ny and nz mean the refractive indices in the x-axis, y-axis and z-axis directions of the base film, retardation layer, liquid crystal layer, retardation film, etc., respectively, and d is the base film, retardation layer, liquid crystal It means the thickness of a layer, retardation film, etc. The x-axis means a direction parallel to the in-plane slow axis, the y-axis means a direction parallel to the in-plane fast axis, and the z-axis means a thickness direction. The x-axis and the y-axis may be perpendicular to each other in a plane. In the present specification, while describing the Rin value, the Rth value, and the refractive index, it means the Rin value, the Rth value, or the refractive index for light having a wavelength of about 550 nm, unless otherwise specified.

The thickness of the base film may be, for example, 10 μm to 100 μm. When the thickness of the base film is within the above range, it may be advantageous for water vapor permeability of the base film, thinning of the polarizing plate, and implementation of rollable properties.

A first barrier layer and a second barrier layer may be laminated on the base film. The first barrier layer and the second barrier layer may be sequentially stacked in the opposite direction in which the retardation layer of the base film exists.

The barrier film may have a multilayer structure in which a first barrier layer and a second barrier layer are laminated, thereby improving barrier performance against an external environment such as moisture. In one example, the moisture permeability of the first barrier layer and the second barrier layer may be 10 ^-4 g/m ² ·day to 10 ^-6 g/m ² ·day. The moisture permeability may be a value measured in a state in which the first barrier layer and the second barrier layer are stacked. When the moisture permeability of the first and second barrier layers satisfies the above range, the OLED device can be effectively protected from moisture. If the moisture permeability exceeds the above range, moisture may penetrate into the OLED device and the OLED device may be damaged, resulting in deterioration of sunspots.

Each of the first barrier layer and the second barrier layer may be an inorganic thin film layer. The inorganic thin film layer may include, for example, at least one inorganic compound selected from the group consisting of oxides, nitrides, hydrides, and complex compounds. Elements constituting the inorganic compound include silicon (Si), nitrogen (N), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), zinc (Zn), tin (Sn), nickel (Ni), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), or yttrium (Y) can be exemplified.

In one example, each of the first and second barrier layers may include a SiOxNy compound. The SiOxNy compound may be suitable as a material for allowing the first barrier layer and the second barrier layer to exhibit water vapor permeability within the above range. In SiOxNy, x and y are x+y=1, and 0≤x≤1 or 0≤y≤1 may be satisfied.

Each of the first and second barrier layers may include a SiOxNy compound as a main component. For example, the first and second barrier layers may each contain the SiOxNy compound in a ratio of 80 wt% or more, 85 wt% or more, 90 wt% or more, or 95 wt% or more.

In one example, the SiOxNy compound may be polysilazane. Polysilazane is a kind of silicone compound and may refer to a polymer having a backbone of a Si-N bond. Specifically, the polysilazane may be a polymer including "-(SiR ₁ R ₂ -NR ₃ )-" as a repeating unit. The R ₁ , R ₂ , and R ₃ may each independently be a hydrogen atom, an oxygen atom, or an organic substituent. In one example, at least one of R ₁ , R ₂ , and R ₃ may include an oxygen atom in the polysilazane. In one example, each of the first and second barrier layers may include a modified SiOxNy compound, for example, plasma-treated as described below. A denaturation process, for example, a plasma process is demonstrated concretely below.

The thickness of the first barrier layer and the second barrier layer may be in the range of 50 nm to 200 nm, respectively. When the thickness of the first barrier layer and the second barrier layer is within the above range, it may be advantageous for moisture permeability within the above range, thinning the polarizing plate, and implementing rollable characteristics.

The barrier film may be formed by forming a first barrier layer on a base film and forming a second barrier layer on the first barrier layer.

In one example, the first barrier layer may be formed by forming a layer of SiOxNy on a base film. The layer of SiOxNy can be formed by coating SiOxNy on a base film. The coating process may be performed by, for example, coating a solution containing SiOxNy and a solvent. An organic solvent may be used as the solvent. As the SiOxNy, polysilazane may be used as described above. In addition, in forming the layer of SiOxNy, after the coating process, a drying process may be further included. The temperature and time conditions of the drying process are not particularly limited and may be appropriately selected within the range in which the solvent is removed. In addition, in forming the SiOxNy layer, after the drying process, a curing process may be further included. The curing may be performed by irradiation of light, for example, irradiation of ultraviolet rays or application of heat.

In one example, a denaturation treatment, for example, a plasma treatment may be further performed on the SiOxNy layer formed on the base film. Through this, it may be more advantageous to allow the first barrier layer to have moisture permeability within the above-described range. In one example, the plasma treatment may be performed by a plasma enhanced chemical vapor deposition (PECVD) method. The PECVD method may be performed by using oxygen as a reaction gas. This will be specifically described below.

On the other hand, the method of forming the second barrier layer is the same as the method of forming the first barrier layer. For example, the second barrier layer may be formed in the same manner as in the forming method of the first barrier layer, except that the second barrier layer is formed on the first barrier layer, not the base film.

Hereinafter, polysilazane as the SiOxNy compound will be used as an example, and the above-mentioned modification treatment, for example, plasma treatment will be described in detail. The polysilazane layer subjected to the modification treatment, for example, plasma treatment, may be referred to as a modified polysilazane layer.

Each of the first and second barrier layers may be formed by plasma-treating the polysilazane layer under a condition in which water vapor is present to form a modified polysilazane layer having significantly increased barrier properties. Although it is not clear why the barrier properties increase when the denaturation treatment is performed in a steam atmosphere, hydrogen radicals dissociated from water vapor in the processing space detach and combine hydrogen atoms of polysilazane to form hydrogen (H ₂ ). This is expected to be due to the increased reactivity of

For example, the modification treatment of the polysilazane layer may be performed in a state where the vapor pressure of water vapor in the processing space is maintained at 5% or more. In the present specification, the steam vapor pressure may mean a percentage of the injection flow rate of the injected water vapor to the total flow rate of the gases injected into the processing space. For example, when performing the plasma treatment while injecting water vapor, discharge gas, and reaction gas at flow rates of A sccm, B sccm, and C sccm, respectively, into a chamber that is a processing space, the water vapor vapor pressure is 100×A/(A +B+C). In another example, the water vapor vapor pressure may be about 10% or more, about 15% or more, about 20% or more, about 25% or more, or about 30% or more. The upper limit of the vapor pressure of water vapor is not particularly limited, and for example, about 90% or less, about 85% or less, about 80% or less, about 75% or less, about 70% or less, about 65% or less, about 60% or less, about 55% or less, about 50% or less, about 45% or less, about 40% or less, or about 35% or less.

A method of maintaining the water vapor vapor pressure in the processing space in the above range is not particularly limited.

For example, the transformation treatment may be performed while injecting water vapor, discharge gas, and oxygen into the processing space. In this case, the water vapor vapor pressure may be controlled by controlling the injection flow rate. In an exemplary method, the modification treatment may be performed while injecting water vapor at a flow rate of 50 sccm or more into the processing space. In another example, the injection flow rate of the water vapor is 55 sccm or more, 60 sccm or more, 65 sccm or more, 70 sccm or more, 75 sccm or more, 80 sccm or more, 85 sccm or more, 90 sccm or more, 95 sccm or more, 100 sccm or more, 105 or more. sccm or more, 110 sccm or more, 115 sccm or more, or 120 sccm or more. The upper limit of the injection flow rate is not particularly limited, and for example, the injection flow rate may be about 500 sccm or less, 400 sccm or less, 300 sccm or less, 200 sccm or less, or about 150 sccm or less.

The partial pressure of hydrogen in the processing space can be controlled by maintaining the vapor pressure of water vapor as described above in the processing space. As described above, the reason for the increase in barrier properties by the modification treatment in a water vapor atmosphere is hydrogen desorption of the polysilazane layer by hydrogen radicals generated from the water vapor, whereby the partial pressure of hydrogen in the processing space can be adjusted. . In one example, the hydrogen (H ₂ ) partial pressure in the processing space in which the denaturation treatment is performed may be about 2.00×10 ⁻⁵ Pa or more. The upper limit of the hydrogen partial pressure is not particularly limited, and for example, about 1.00×10 ^-4 Pa or less, about 9.00×10 ^-5 Pa or less, about 8.00×10 ^-5 Pa or less, about 7.00×10 ^-5 Pa or less , about 6.00×10 ^-5 Pa or less, about 5.00×10 ^-5 Pa or less, or about 4.50×10 ^-5 Pa or less. This partial pressure of hydrogen can be achieved by controlling the partial pressure of water vapor in the processing space or an injection flow rate thereof, and in this range, a barrier film having excellent barrier properties can be obtained.

Under the above conditions, polysilazane may be denatured by performing a denaturation treatment, that is, plasma treatment, and a barrier layer may be formed.

The plasma treatment may be performed by performing the plasma discharge treatment while supplying a discharge gas capable of forming a plasma state. As the discharge gas applicable to the above, nitrogen gas and/or as an atom of group 18 of the periodic table, helium, neon, argon, krypton, xenon, or radon may be used.

Accordingly, when the transformation treatment is a plasma treatment, the transformation treatment may be performed while injecting discharge gas and water vapor into the processing space. As the discharge gas, the above-mentioned kinds can be used.

When the discharge gas is injected, the ratio (H/N) of the injection flow rate (N) of the discharge gas to the injection flow rate (H) of the water vapor may be maintained at 0.4 or more. The ratio (H/N) may be maintained at about 0.45 or more or about 0.5 or more in another example. The upper limit of the ratio (H/N) is not particularly limited, and for example, about 10 or less, about 9 or less, about 8 or less, about 7 or less, about 6 or less, about 5 or less, about 4 or less, about 3 or less , about 2 or less, about 1 or less, or about 0.9 or less. The denaturation treatment can be effectively performed under this range.

The denaturation treatment may be performed while supplying oxygen having an oxidizing property as a reaction gas into the processing space. Accordingly, the denaturation treatment may be performed while injecting water vapor and oxygen into the processing space. In this case, the ratio (H/O) of the injection flow rate O of oxygen gas into the processing space and the injection flow rate H of water vapor may be about 0.4 or more. The ratio (H/O) may be maintained at about 0.45 or more or about 0.5 or more in another example. The upper limit of the ratio (H/O) is not particularly limited, and for example, about 10 or less, about 9 or less, about 8 or less, about 7 or less, about 6 or less, about 5 or less, about 4 or less, about 3 or less , about 2 or less, about 1 or less, or about 0.9 or less. The denaturation treatment can be effectively performed under this range.

As described above, the discharge conditions for the transformation treatment performed while injecting water vapor, discharge gas and/or reaction gas, that is, plasma treatment, are not particularly limited, and may be selected in consideration of process efficiency, etc. or the type or flow rate of the injected gas. have. For example, the plasma discharge treatment may be performed so that the power density per unit area of the electrode is about 0.2 W/cm ² or more. In another example, the power density may be about 0.4 W/cm ² or more, about 0.6 W/cm ² or more, about 0.8 W/cm ² or more, or about 0.9 W/cm ² or more. In addition, the power density may be about 5 W/cm ² or less, 4 W/cm ² or less, 3 W/cm ² or less, 2 W/cm ² or less, or 1.5 W/cm ² or less.

However, the range of the power density is exemplary, and the specific range may be determined depending on the desired processing energy and the configuration of the barrier film to be treated, for example, the type of the base film of the barrier film. That is, since the processing energy is determined by the product of the power density and the processing time, in order to secure the target processing energy in a short time, the power density is increased, and if the power density is decreased, the time for securing the processing energy is increased. However, if the power density is too high, damage to the base film (appearance deformation, etc.) may occur depending on the type of the base film. For example, in the case of a base film having heat resistance, etc., the processing time required to secure the target processing energy can be shortened by increasing the power density.

In addition, the treatment energy during plasma treatment can be maintained at about 2 J/cm ² or more. The treatment energy is 3 J/cm ² or more, 4 J/cm ² or more, 5 J/cm ² or more, 6 J/cm ² or more, 7 J/cm ² or more, 8 J/cm ² or more, 9 J/ cm ² or more, 10 J/cm ² or more, 11 J/cm ² or more, or 12 J/cm ² or more. The treatment energy is 30 J/cm ² or less, 28 J/cm ² or less, 26 J/cm ² or less, 24 J/cm ² or less, 22 J/cm ² or less. or less, 20 J/cm ² or less, 18 J/cm ² or less, 16 J/cm ² or less, or 14 J/cm ² or less, but is not limited thereto.

The specific range of processing energy may be changed in consideration of the state of the polysilazane layer requiring processing, for example, its thickness. In general, a larger thickness may increase the amount of processing energy because more energy is required for the reaction. However, since damage such as cracks may be induced even when the thickness of the polysilazane layer is excessively thick as described above, the processing energy may also be adjusted according to an appropriate thickness of the polysilazane layer.

The process pressure during the plasma treatment may be maintained in a range of 50 mTorr or more. The process pressure is in another example about 60 mTorr or more, 70 mTorr or more, 80 mTorr or more, 90 mTorr or more, or 100 mTorr or more, or about 500 mTorr or less, about 450 mTorr or less, about 400 mTorr or less, about 350 mTorr or less, or about It can be maintained within the range of 300 mTorr or less.

The temperature at which the plasma treatment is performed is not particularly limited, but when the temperature is increased, the reaction for forming the barrier layer may be more smoothly performed, so it may be appropriate to perform the plasma treatment at room temperature or higher. For example, the process temperature during the denaturation treatment may be 30 °C or more, 40 °C or more, 50 °C or more, 60 °C or more, 70 °C or more, or 80 °C or more. In another example, the process temperature may be about 85 °C or more, about 90 °C or more, about 95 °C or more, about 100 °C or more, about 105 °C or more, or about 110 °C or more. The process temperature is about 200 °C or less, about 190 °C or less, about 180 °C or less, about 170 °C or less, about 160 °C or less, about 150 °C or less, about 140 °C or less, about 130 °C or less or below about 120°C.

The process pressure and process temperature may be adjusted in consideration of desired barrier properties and/or process efficiency.

The plasma treatment time may be appropriately adjusted so that the barrier layer exhibits appropriate barrier properties, for example, may be performed for about 10 seconds to 10 minutes. However, the processing time is an example, and the specific processing time may be determined according to a power density according to a desired level of processing energy, as described above.

The modified polysilazane layer having barrier properties may be formed by modifying the polysilazane layer by the modification treatment under the above conditions.

The retardation layer and the barrier film may be attached via an adhesive layer. The pressure-sensitive adhesive window may be formed on one surface of the base film of the barrier film. As the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or a urethane pressure-sensitive adhesive may be used without any particular limitation.

The retardation layer may have a λ/4 phase delay characteristic. In the present specification, the term λ/n phase delay characteristic means a characteristic capable of retarding incident light by n times the wavelength of the incident light within at least a partial wavelength range. The λ/4 phase delay characteristic may be a characteristic of converting incident linearly polarized light into elliptically polarized light or circularly polarized light, and converts reversely incident elliptically polarized light or circularly polarized light into linearly polarized light. Since the retardation layer having a λ/4 phase delay characteristic can be applied to the OLED panel to prevent reflection of external light, it is possible to implement a black visual sensation when the power is off. The Rin value of the retardation layer having the λ/4 phase delay characteristic with respect to light having a wavelength of 550 nm may be in the range of 100 nm to 200 nm, 100 to 180 nm, 100 to 150 nm, or 130 nm to 150 nm.

The retardation layer may have a single-layer structure or a multi-layer structure in which two or more layers are stacked. When the retardation layer has a multilayer structure, each layer may be attached to each other through an adhesive or an adhesive, or may be laminated to each other by direct coating.

In one example, the retardation layer may have a multilayer structure in which a first liquid crystal layer and a second liquid crystal layer are stacked. In this case, the first liquid crystal layer may be disposed closer to the polarizer than the second liquid crystal layer. 2 exemplarily shows a polarizing plate in which the retardation layer 20 has a multilayer structure in which a first liquid crystal layer 201 and a second liquid crystal layer 202 are stacked. In one example, the first liquid crystal layer may have a λ/2 phase delay characteristic, and the second liquid crystal layer may have a λ/4 phase delay characteristic. The in-plane retardation value of the first liquid crystal layer with respect to a wavelength of 550 nm may be in the range of 200 nm to 300 nm. The in-plane retardation value of the second liquid crystal layer with respect to a wavelength of 550 nm may be in the range of 100 nm to 150 nm.

The first liquid crystal layer and the second liquid crystal layer may each include a liquid crystal compound. The liquid crystal compound may be a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound. When the liquid crystal layer includes the rod-shaped liquid crystal compound, the slow axis of the liquid crystal layer may refer to the direction of the long axis of the rod shape. When the liquid crystal layer includes a disk-shaped liquid crystal compound, the slow axis of the liquid crystal layer may mean a normal direction of the disk shape.

In one example, the first liquid crystal layer and the second liquid crystal layer may each include a liquid crystal compound in a horizontally aligned state. In the present specification, the horizontal alignment refers to a state in which the slow axis of the liquid crystal compound is oriented so as to be horizontal with respect to the plane of the liquid crystal layer, for example, at an angle of 0 degrees to 10 degrees, 0 degrees to 5 degrees, or 0 degrees to 3 degrees. can mean

In one example, the first liquid crystal layer having the λ/2 phase delay characteristic may include a rod-shaped liquid crystal compound. The second liquid crystal layer having the λ/4 phase delay characteristic may include a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound. An angle between the slow axis of the first liquid crystal layer and the absorption axis of the polarizer may be in the range of 0 degrees to 45 degrees. Also, the angle between the slow axis of the second liquid crystal layer and the absorption axis of the polarizer may be in the range of 45 degrees to 90 degrees. Within this angular range, the entire retardation layer may be suitable for exhibiting a λ/4 phase delay characteristic.

In another example, the first liquid crystal layer having the λ/2 phase delay characteristic may include a disk-shaped liquid crystal compound. The second liquid crystal layer having the λ/4 phase delay characteristic may include a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound. An angle between the slow axis of the first liquid crystal layer and the absorption axis of the polarizer may be in the range of 45 degrees to 90 degrees. Also, the angle between the slow axis of the second liquid crystal layer and the absorption axis of the polarizer may be in the range of 0 degrees to 45 degrees. Within this angular range, the entire retardation layer may be suitable for exhibiting a λ/4 phase delay characteristic.

In one example, the retardation layer may have a multilayer structure in which a first retardation film having an Nz value of 0.8 to 1.2 calculated by Equation 3 below and a second retardation film satisfying Equation 4 are stacked. In this case, the first retardation film may be disposed closer to the polarizer than the second retardation film. Alternatively, the second retardation film may be disposed closer to the polarizer than the first retardation film. 3 exemplarily shows a polarizing plate having a multilayer structure in which the retardation layer 20 is laminated with a first retardation film 203 and a second retardation film 204 .

[Equation 3]

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

[Equation 4]

nx ≒ ny < nz

In Equations 3 and 4, nx, ny, and nz mean the refractive index for a wavelength of 550 nm in the x-axis, y-axis and z-axis directions of the retardation film, respectively, and the definition of the x-axis, y-axis and z-axis directions is as described above. same.

The first retardation film may have a λ/4 retardation characteristic. The first retardation film may have an in-plane retardation value for light having a wavelength of 550 nm, 100 nm to 150 nm, or 130 nm to 150 nm. When the Rin value is within the above range, excellent external light reflection prevention performance may be exhibited.

An angle between the slow axis of the first retardation film and the absorption axis of the polarizer may be in the range of 40 degrees to 50 degrees. Excellent anti-reflection performance of external light may be exhibited within this angle range.

A value of the first retardation film R(450)/R(550) may be in the range of 0.6 to 1.2. In the above, R(λ) may mean an in-plane retardation value of the retardation film with respect to a wavelength of λnm. Excellent anti-reflection performance of external light may be exhibited within this dispersion value range.

The second retardation film satisfying the refractive index relationship of Equation 4 may be advantageous in that it can improve the external light reflection prevention performance from the side. The thickness direction retardation value of the second retardation film may be greater than 0 nm, specifically 30 nm to 300 nm. Within this thickness direction retardation value range, it may be advantageous to improve the anti-reflection performance of external light from the side.

Each of the first and second retardation films may be a liquid crystal film or a polymer film. For example, each of the above films may be formed by using a film obtained by stretching a light-transmitting polymer film capable of imparting optical anisotropy by stretching in an appropriate manner, or by using a liquid crystal film formed by aligning a liquid crystal compound. . In addition, an unstretched polymer film may be used as long as it has optical anisotropy.

In one example, an adhesive layer may be formed on one or both surfaces of the polarizer to attach another layer. 4 exemplarily shows a polarizing plate in which adhesive layers 50A and 50B are formed on both surfaces of the polarizer 10 and other layers 60A and 60B are formed via the adhesive layer.

The adhesive layer may be a light-curable adhesive layer or a heat-curable adhesive layer. In the present specification, the light-curable adhesive refers to an adhesive that is cured by irradiation of light, for example, ultraviolet or visible light, and the heat-curable adhesive refers to an adhesive that is cured by application of heat. In one example, an ultraviolet curable adhesive may be used as the adhesive layer, for example, an epoxy-based adhesive or an acrylic adhesive may be used. In one example, the other layer 60A that may be attached to the polarizer via the adhesive layer 50A may be a surface treatment layer.

The surface treatment layer may be attached to the opposite side of the polarizer on which the retardation layer is disposed. The surface treatment layer includes an anti-fog layer, a self-healing layer, an anti-reflection layer, an anti-finger layer, an anti-fouling layer ( It may include an anti-fouling layer, an anti-glare layer, a mirror layer, or a hardness enhancing layer. The hardness enhancing layer is also commonly referred to as a “hard coating layer” in the art. The material, formation method, physical properties, etc. of the surface treatment layer are not particularly limited, and contents known in the art may be applied.

The surface treatment layer may have a single layer structure having any one of the above types, or a multilayer structure in which two or more types of layers are stacked. According to an embodiment of the present application, the surface treatment layer may have a multilayer structure of an anti-reflection layer formed on the hard coating layer. The thickness of the hard coating layer may be, for example, in the range of 1 μm to 10 μm, but is not limited thereto. The thickness of the anti-reflection layer may be, for example, in the range of 10 nm to 500 nm, but is not limited thereto. The anti-reflection layer may be appropriately structurally designed to have low reflection properties. The anti-reflection layer may have an average reflectance for a wavelength of 380 nm to 780 nm, for example, 5% or less, 3% or less, or 1% or less, but is not limited thereto.

As another layer 60B that may be attached to the polarizer via the adhesive layer 50B, a protective film of the polarizer or a base film of the retardation layer may be exemplified. The protective film or the base film of the retardation layer may be attached to a surface on which the retardation layer is disposed in the polarizer. As the base film of the protective film or retardation layer of the polarizer, for example, a cellulose film such as a TAC (Triacetyl cellulose) film; polyester films such as PET (poly(ethylene terephthalate)) films; polycarbonate film; polyethersulfone film; An acrylic film and/or a polyethylene film, a polypropylene film, a polyolefin film including a cyclo- or norbornene structure, or a polyolefin-based film such as an ethylene-propylene copolymer film may be used, but is not limited thereto.

As described above, the polarizer and the retardation layer may be attached via the adhesive layer. When the retardation layer includes the base film for forming the aforementioned liquid crystal layer, the base film and the polarizer may be in a state in which the polarizer is attached via an adhesive layer.

The polarizing plate may further include an adhesive layer on one surface of the barrier film. 5 exemplarily shows a polarizing plate further including an adhesive layer 70 on one surface of the barrier film 30 . The pressure-sensitive adhesive layer formed on one surface of the base film of the barrier film to distinguish it from the pressure-sensitive adhesive layer present between the base film and the retardation layer of the barrier film as the first pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer formed on one side of the second barrier layer of the barrier film may be referred to as a second pressure-sensitive adhesive layer. The second pressure-sensitive adhesive layer may perform a function of attaching the polarizing plate to the OLED panel. As the second pressure-sensitive adhesive layer, a known pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or a urethane pressure-sensitive adhesive may be used without any particular limitation.

This application relates to the use of the polarizing plate. In one example, the polarizing plate may be applied to an organic light emitting diode display.

6 exemplarily shows an organic light emitting display device to which a polarizing plate is applied. As shown in FIG. 6 , the organic light emitting display device may include an organic light emitting display panel 200 and the polarizing plate 100 disposed on one surface of the organic light emitting display panel 200 . In this case, the barrier film may be disposed closer to the organic light emitting display panel than the polarizer of the polarizing plate.

The organic light emitting display panel may include a base substrate, a lower electrode, an organic light emitting layer including an organic material, and an upper electrode. If necessary, an encapsulation substrate may be additionally formed on the upper electrode. One of the lower electrode and the upper electrode may be an anode and the other may be a cathode. The anode is an electrode into which holes are injected and may be made of a conductive material having a high work function, and the cathode is an electrode into which electrons are injected and may be made of a conductive material having a low work function. At least one of the lower electrode and the upper electrode may be made of a transparent conductive material through which emitted light may come out, and may include, for example, a transparent metal oxide such as ITO or IZO. The organic emission layer may include an organic material capable of emitting light when a voltage is applied to the lower electrode and the upper electrode.

The organic light emitting display panel may further include an auxiliary layer between the lower electrode and the organic light emitting layer and between the upper electrode and the organic light emitting layer. The auxiliary layer includes a hole transporting layer, a hole injecting layer, an electron injecting layer and/or an electron transporting layer for balancing electrons and holes. can, but is not limited thereto. The encapsulation substrate may be made of glass, metal, and/or polymer, and may prevent the inflow of moisture and/or oxygen from the outside by sealing the lower electrode, the organic light emitting layer, and the upper electrode.

The polarizing plate may be disposed on a side from which light is emitted from the organic light emitting display panel. For example, in the case of a bottom emission structure in which light is emitted toward the base substrate, it may be disposed on the outside of the base substrate, and in the case of a top emission structure in which light is emitted toward the encapsulation substrate, it may be disposed outside the encapsulation substrate. have.

The polarizing plate has excellent antireflection performance of external light, excellent barrier performance against external environments such as moisture, and can be thinned and rolled, so that it is applied to an organic light emitting display device to improve black visibility and improve durability , enabling miniaturization of the device and the implementation of rollable devices.

The polarizing plate of the present application has excellent antireflection performance of external light, as well as excellent barrier performance against external environments such as moisture, and can be thinned and rolled. Such a polarizing plate may be applied to an OLED display and may be suitable for improving black visual perception, improving durability, miniaturizing a device, and implementing a rollable device.

1 to 5 exemplarily show the polarizing plate of the present application.
6 exemplarily shows the organic light emitting display device of the present application.
7 exemplarily shows the polarizing plate of Example 1.

Hereinafter, the present application will be specifically described through Examples according to the present application and Comparative Examples not according to the present application, but the scope of the present application is not limited by the Examples presented below.

Example One

A polarizing plate having the structure of FIG. 7 was manufactured according to the following method.

After coating an aryl-based hard coating layer to a thickness of 6 μm on a TAC (Tri-Acetyl Cellulose) base film having a thickness of 40 μm, an anti-reflection layer having a reflectance of 0.9% on the hard coating layer is coated to a thickness of 100 nm. (60A) was prepared.

The PVA-based polarizer 10 was prepared by a wet stretching method (using a product name M3000 machine by Nippon gosei).

A first liquid crystal layer (manufactured by Merck) 201 having a Rin value of 257 nm is formed on the TAC base film 60B having a thickness of 40 μm, and a second liquid crystal layer having a Rin value of 128 nm on the first liquid crystal layer ( Merck Co.) 202 was formed, but the retardation layer 20 having a λ/4 phase delay characteristic was prepared by forming the slow axis of the first liquid crystal layer and the slow axis of the second liquid crystal layer to form 60 degrees.

UV-curable (epoxy-based) adhesives (50A, 50B) were prepared as adhesives.

As an adhesive, an acrylic adhesive (LGC's S7 product) (40, 70) was prepared.

A COP film having a WVTR value of 5 g/m ^2· day and a thickness of 50 μm was prepared as the base film 300 .

A first barrier layer 301 including a SiOxNy compound and having a thickness of 150 nm is formed on the base film 300, and a second barrier layer including a SiOxNy compound and having a thickness of 150 nm on the first barrier layer By forming (302), the barrier film (30) was prepared. Specifically, after forming a layer of polysilazane on the base film, the first barrier layer is formed by plasma treatment using a PECVD method. PECVD process conditions are, the process pressure is 125 mTorr, the energy during plasma treatment is 20 J/cm ² , the process temperature is 100 ° C, Ar 350ccm is used as the discharge gas, O ₂ 350ccm was used as the reaction gas. . Next, after forming a layer of polysilazane on the first barrier layer, a second barrier layer is formed by plasma treatment using a PECVD method. The PECVD process conditions of the second barrier layer are the same as the PECVD process conditions of the first barrier layer. The measured WVTR value for the laminate of the first barrier layer and the second barrier layer was 10 ⁻⁵ g/m ^2· day.

The surface treatment layer 60A was attached to one side of the polarizer 10 via the adhesive 50A, and the retardation layer 20 was attached to the opposite side of the polarizer 10 via the adhesive 50B. . At this time, the base film 60B of the retardation layer was attached so as to be in contact with the polarizer 10 . At this time, the angle between the light absorption axis of the polarizer and the slow axis of the first liquid crystal layer 201 was attached to be 45 degrees.

The retardation layer 20 and the barrier film 30 were attached to each other through an adhesive 40 . At this time, the base film 300 of the barrier film 30 was attached to be in contact with the second liquid crystal layer 202 of the retardation layer. Next, an adhesive 70 was additionally formed on the second barrier layer 302 to prepare a polarizing plate.

comparative example One

Instead of the barrier film, a polarizing plate having the structure of Comparative Example 1 was prepared in the same manner as in Example 1, except that a glass having a thickness of 0.7T was attached to the retardation layer through an adhesive.

comparative example 2

As a barrier film, a polarizing plate of Comparative Example 2 was prepared in the same manner as in Example 1, except that only one barrier layer having a thickness of 150 nm and including a SiOxNy compound was formed on the base film. The method of forming the barrier layer of Comparative Example 2 is the same as the method of forming the first barrier layer of Example 1.

Measurement example 1. Water vapor permeability measurement

In the above, the water vapor permeability of the base film, the barrier layer, and the barrier film was measured by the moisture permeability method using Mokon's aquatran2 equipment at a temperature of 38° C. and 100% relative humidity.

evaluation example One. barrier performance evaluation

In order to evaluate the barrier performance against moisture of the polarizing plate, moisture vapor permeability was measured for the 0.7T glass of Comparative Example 1, the barrier film of the first barrier layer of Comparative Example 2, and the barrier film of the second barrier layer of Example 1. In order to prevent deterioration of OLED devices due to moisture, a film with WVTR 10 ^-4 g/m ^2· day or less is required. Existing 0.7T glass had a WVTR of an unmeasurable level, but it could not be rolled as in Evaluation Example 2. For rollable, it is necessary to apply a polymer film. In Comparative Example 2, rollable is possible by applying a polymer film, but since it is a barrier film of one barrier layer, it has only WVTR 10 ^-3 g/m ^{2 ·} day performance, and thus is vulnerable to OLED device protection. On the other hand, since the barrier film of the second barrier layer of Example 1 has a WVTR of 10 ^-5 g/m ^2· day or less, it is suitable for protecting an OLED device.

number of measurements
WVTR (g/m ² day) Comparative Example 1
(0.7T glass) Comparative Example 2
(Barrier 1st floor) Example 1
(Barrier 2nd floor) #One not measurable 5 x 10 ^-3 2 x 10 ^-5 #2 not measurable 3 x 10 ^-3 2 x 10 _-5 #3 not measurable 3 x 10 ^-3 3 x 10 ^-5 #4 not measurable 4 x 10 ^-3 2 x 10 ^-5 #5 not measurable 5 x 10 ^-3 3 x 10 ^-5

evaluation example 2. rollable performance evaluation

In order to evaluate the rollable performance of the polarizing plate, as shown in the schematic diagram of FIG. 8, rolling evaluation of repeating winding and unfolding for the polarizing plates of Comparative Example 1 and Example 1 (width: 1445.48mm, length: 821.02mm) was performed did. As shown in FIG. 9 , it can be seen that Comparative Example 1 is not rolled, and Example 1 is rollable. In addition, in the case of Example 1, it was confirmed that there was no problem with the product up to 51,000 times of rolling repeated evaluation.

Comparative Example 1
(0.7T glass) Example 1
(Barrier 2nd floor) Rolling availability no rolling OK for 51,000 repetitions

10: polarizer 20: retardation layer 201: first liquid crystal layer 202: second liquid crystal layer 203: first retardation film 204: second retardation film 30: barrier film 300: base film 301: first barrier layer 302: second barrier Layer 40: first pressure-sensitive adhesive layer 50A, 50B: adhesive layer 60A, 60B: another layer 70: second pressure-sensitive adhesive layer

Claims (17)

A polarizer, a retardation layer and a barrier film are sequentially included,
The retardation layer has a λ/4 phase delay characteristic,
The barrier film includes a base film, a first barrier layer formed on the base film, and a second barrier layer formed on the first barrier layer,
The absolute value of the in-plane retardation value and the thickness direction retardation value for the 550 nm wavelength of the base film is 10 nm or less, respectively,
The first barrier layer and the second barrier layer are each an inorganic thin film layer,
The moisture permeability of the base film is 1 g/m ² ·day to 100 g/m ² ·day,
The moisture vapor permeability of the first barrier layer and the second barrier layer is 10 ^-4 g/m ² ·day to 10 ^-6 g/m ² ·day,
The moisture permeability of the barrier film is 10 ^-4 g/m ² ·day or less,
A polarizing plate to which the retardation layer and the barrier film are attached via an adhesive layer. delete The polarizing plate according to claim 1, wherein the base film has a thickness of 10 µm to 100 µm. The polarizing plate according to claim 1, wherein the base film comprises an acrylic film or a COP (Cyclo-olefin polymer)-based film. The polarizing plate of claim 1 , wherein the first barrier layer and the second barrier layer each include a SiOxNy compound. The polarizing plate of claim 1 , wherein the first barrier layer and the second barrier layer each have a thickness of 50 nm to 200 nm. The λ of claim 1, wherein the retardation layer has a first liquid crystal layer having a λ/2 phase delay characteristic in which the in-plane retardation value for a wavelength of 550 nm is in the range of 200 nm to 300 nm, and the in-plane retardation value for a wavelength of 550 nm is λ in the range of 100 nm to 150 nm A polarizing plate having a multilayer structure in which a second liquid crystal layer having a /4 phase delay characteristic is laminated. The method according to claim 7, wherein the first liquid crystal layer includes a rod-shaped liquid crystal compound, and the angle between the slow axis of the first liquid crystal layer and the absorption axis of the polarizer is in the range of 0 degrees to 45 degrees, and An angle between the slow axis and the absorption axis of the polarizer is in the range of 45 degrees to 90 degrees. The method of claim 7, wherein the first liquid crystal layer comprises a disk-shaped liquid crystal compound, the angle between the slow axis of the first liquid crystal layer and the absorption axis of the polarizer is in the range of 45 degrees to 90 degrees, and the second liquid crystal layer An angle between the slow axis of and the absorption axis of the polarizer is in the range of 0 degrees to 45 degrees. The polarizing plate of claim 1 , wherein the retardation layer has a multilayer structure in which a first retardation film having an Nz value of 0.8 to 1.2 of Equation 3 and a second retardation film satisfying Equation 4 are stacked:
[Equation 3]
Nz = (nx-nz)/(nx-ny)
[Equation 4]
nx ≒ ny < nz
In Equations 3 and 4, nx, ny, and nz denote refractive indices for a wavelength of 550 nm in the x-axis, y-axis, and z-axis directions of the retardation film, respectively. The polarizing plate of claim 10 , wherein an angle between the slow axis of the first retardation film and the absorption axis of the polarizer is within a range of 40 degrees to 50 degrees. 11. The method of claim 10, wherein the R (450) / R (550) value of the first retardation film is in the range of 0.6 to 1.2, the R (450) means the in-plane retardation value of the first retardation film with respect to a wavelength of 450 nm and R (550) is a polarizing plate that means an in-plane retardation value of the first retardation film with respect to a wavelength of 550 nm. The polarizing plate of claim 10 , wherein the thickness direction retardation value of the second retardation film is 30 nm to 300 nm. The polarizing plate according to claim 1, wherein an ultraviolet curable adhesive layer is formed on one or both surfaces of the polarizer. The polarizing plate according to claim 14, further comprising a surface treatment layer attached to one surface of the polarizer via the UV curable adhesive layer. The polarizing plate according to claim 1, further comprising a second pressure-sensitive adhesive layer on one surface of the barrier film. An organic light emitting diode display comprising an organic light emitting display panel and the polarizing plate of claim 1, wherein a barrier film is disposed closer to the organic light emitting display panel than the polarizer of the polarizing plate.

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