KR102577329B1 - Polarizing plates and uses thereof - Google Patents

Abstract

This application relates to polarizers and uses of polarizers. The polarizer of the present application not only has excellent anti-reflection performance, but can also achieve a black visual sensation close to neutral in all directions on the side. The polarizing plate of the present application can be applied to an organic light emitting display device to improve viewing angle reflection characteristics.

Description

Polarizing plates and uses thereof}

This application relates to polarizers and uses of polarizers.

Recently, there has been a demand for lighter and thinner monitors or televisions, and in response to these demands, organic light emitting devices (OLEDs) are attracting attention. An organic light emitting device is a self-emitting display device that emits light on its own and does not require a separate backlight, so it can reduce thickness and is advantageous in implementing a flexible display device.

Meanwhile, an organic light emitting device may reflect external light by metal electrodes and metal wires formed on the organic light emitting display panel, and the reflected external light may reduce visibility and contrast ratio, resulting in poor display quality. As in Patent Document 1, by attaching a circular polarizer to one side of the organic light emitting display panel, leakage of the reflected external light can be reduced.

However, currently developed circular polarizers have a problem in that they have a strong dependence on viewing angle, so anti-reflection performance deteriorates toward the side, resulting in poor visibility.

Republic of Korea Patent Publication No. 2009-0122138

The present application provides a polarizer that not only has excellent anti-reflection performance but can also realize a black viewing sensation close to neutral in all directions from the side, and an organic light emitting display device with improved viewing angle reflection characteristics by applying the polarizer.

This application relates to a polarizer. Figure 1 exemplarily shows a polarizing plate of the present application. As shown in FIG. 1, the polarizing plate may include a polarizer 100, a dye layer 200 disposed on one side of the polarizer, and a retardation layer disposed on a side opposite to the dye layer of the polarizer. The phase difference layer may include at least a quarter wave plate 300. The dye layer may include a liquid crystal compound and a dichroic dye in a vertically aligned state. The polarizing plate of the present application not only has excellent anti-reflection performance, but also applies the above-mentioned dye layer to the top of the polarizer, so that the absorption axis of the polarizer and the absorption axis of the dye layer cross from the side, thereby increasing the reflectance. Since it can be reduced, it can be advantageous in realizing a black visual sensation close to neutral in all directions on the side.

In this application, the terms polarizer and polarizer refer to distinct objects. The term polarizer refers to a film, sheet, or device itself that has a polarizing function, and the term polarizer refers to an object that includes the polarizer and other elements laminated on one or both sides of the polarizing device. Other elements in the above may include the liquid crystal layer, a protective film of a polarizer, a retardation layer such as a 1/4 wave plate or a 1/2 wave plate, an adhesive layer, an adhesive layer, a surface treatment layer, etc., but are limited thereto. It doesn't work.

A polarizer is a functional element that can extract light vibrating in one direction from incident light vibrating in multiple directions. As a polarizer, for example, a known absorption type linear polarizer can be used. An example of such a polarizer may be a poly(vinyl alcohol) (PVA) polarizer.

In one example, the polarizer included in the polarizing plate may be a PVA film or sheet on which a dichroic dye or iodine is adsorbed and oriented. The PVA can be obtained, for example, by gelling polyvinylacetate. Examples of polyvinyl acetate include homopolymers of vinyl acetate; and copolymers of vinyl acetate and other monomers. Examples of other monomers copolymerized with vinyl acetate include one or more types of monomers such as unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfonic acid compounds, and acrylamide compounds having an ammonium group. The degree of gelation of polyvinylacetate is generally about 85 mol% to about 100 mol% or 98 mol% to 100 mol%. The degree of polymerization of the polyvinyl alcohol of the linear polarizer may generally be about 1,000 to about 10,000 or about 1,500 to about 5,000.

The transmittance or polarization degree of the polarizer can be appropriately adjusted in consideration of the purpose of the present application. For example, the transmittance of the polarizer at a wavelength of 550 nm may be in the range of 40% to 55% for single transmittance, and the degree of polarization may be in the range of 65% to 99.9997%.

The dye layer may include a liquid crystal compound and a dichroic dye in a vertically aligned state. In the present application, the vertical alignment state refers to a state in which the director of the liquid crystal compound is aligned perpendicular to the plane of the dye layer or liquid crystal layer, for example, about 85 degrees to 95 degrees, preferably about 90 degrees. You can. In the present application, the horizontal alignment state refers to a state in which the director of the liquid crystal compound is arranged parallel to the plane of the dye layer or liquid crystal layer, for example, -5 degrees to 5 degrees, preferably about 0 degrees. You can.

In the present application, the director of the liquid crystal compound may mean the long axis if the liquid crystal compound is rod-shaped, and may mean the axis in the normal direction of the disk plane if the liquid crystal compound is disk-shaped.

The dichroic dye may be aligned according to the orientation of the liquid crystal compound. Therefore, when the liquid crystal compound is included in a vertically aligned state, the dichroic dye may also be included in a vertically aligned state. If the dichroic dye is included in a vertically oriented state, it may exhibit a black appearance in all lateral directions due to its anisotropic absorption characteristics at the viewing angle.

The liquid crystal compound may be a polymerizable or curable liquid crystal compound. In the present application, a polymerizable or curable liquid crystal compound may refer to a molecule that includes a portion capable of exhibiting liquid crystallinity, for example, a mesogen skeleton, and one or more polymerizable or curable functional groups. The polymerizable or curable functional group is not particularly limited, but examples include alkenyl group, epoxy group, cyano group, carboxyl group, acryloyl group, methacryloyl group, acryloyloxy group, or methacryloyloxy group. there is.

The dye layer may include the liquid crystal compound in a cured or polymerized state. In addition, including a polymerizable liquid crystal material in a cured or polymerized state may mean that the liquid crystal compound is polymerized to form a skeleton such as the main chain or side chain of the liquid crystal polymer within the dye layer. The dye layer may include a liquid crystal compound with fixed vertical alignment. Therefore, the vertical alignment state of the liquid crystal compound in the dye layer is not switched by application of external energy such as an electric field.

In this application, “dye” may refer to a material capable of intensively absorbing and/or modifying light within at least part or the entire range of visible light, for example, within the wavelength range of 380 nm to 780 nm, and may be referred to as “exotic color.” “Dye” may refer to a material capable of anisotropic absorption of light in at least part or the entire range of the visible light region.

In the dye layer, dichroic dyes are arranged together according to the arrangement of the liquid crystal compound, and may exhibit anisotropic light absorption characteristics with respect to the alignment direction of the dichroic dye and a direction perpendicular to the alignment direction. In one example, the dichroic dye may have a rod shape. For example, a dichroic dye is a material whose light absorption rate varies depending on the polarization direction. If the absorption rate of light polarized in the major axis direction is high, it is called a p-type dye. If the absorption rate of light polarized in the minor axis direction is high, it is called an n-type dye. It can be called. In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye is absorbed, and polarized light vibrating in the short axis direction of the dye has low absorption and can be transmitted. Hereinafter, unless otherwise specified, the dichroic dye is assumed to be a p-type dye.

As the dichroic dye, for example, a known dye known to have the property of being aligned according to the orientation of the liquid crystal compound can be selected and used. Such dichroic dyes include, for example, azo-based dyes, anthraquinone-based dyes, methine-based dyes, azomethine-based dyes, oxadine-based dyes, azo-based dyes, styryl-based dyes, coumarin-based dyes, porphyrin-based dyes, and dichroic dyes. One or more dyes selected from the group consisting of benzofuranone-based dyes, thiketophyllorophyllo-based dyes, rhodamine-based dyes, xanthene-based dyes, and phyllomethene-based dyes can be used. As for the dichroic dye, one type of dye or a mixture of two or more types of dyes may be used within the range in which the dye layer exhibits the desired transmittance.

The polarizing plate of the present application can adjust reflection visibility characteristics in all lateral directions depending on the dichroic ratio of the dichroic dye. The dichroic ratio of the dichroic dye may be appropriately selected within a range that can achieve the purpose of the present application. In this application, the term "dichroic ratio" means, for example, in the case of a p-type dye, the absorption of polarized light parallel to the long axis direction of the dye divided by the absorption of polarized light parallel to the direction perpendicular to the long axis direction. You can.

For example, the dichroic dye may have a dichroic ratio of 5 or more. The dichroic ratio of the dichroic dye may be a dichroic ratio measured for a dye layer containing the dichroic dye and a liquid crystal compound. The dichroic ratio of the dye layer is the absorption rate in the lateral direction of the dye layer divided by the absorption rate in the normal direction of the dye layer, or the absorption rate of the dye layer for linearly polarized light parallel to the normal direction of the dye layer perpendicular to the normal direction of the dye layer. It can be defined as a value divided by the absorption rate of the dye layer for linearly polarized light parallel to one direction. The method of checking this dichroic ratio is known, and can be predicted, for example, through the ratio of transmittance described later. The dichroic ratio can be measured based on any wavelength within the range of 380 nm to 780 nm, the entire range, or the wavelength of a certain region within the range. In one example, the dichroic ratio introduced into the dye layer It can be measured based on the maximum absorption wavelength of the dichroic dye, or about 550 nm. The upper limit of the dichroic ratio may be, for example, 100 or less or 90 or less. The dichroic ratio of the dye layer containing the dichroic dye can be adjusted by adjusting the content of the dichroic dye or by applying a liquid crystal compound with excellent orientation characteristics (for example, smectic liquid crystal).

The content of the dichroic dye in the dye layer can be appropriately adjusted within a range that can obtain the effect of the present application. For example, the dichroic dye may be included in the dye layer in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the liquid crystal compound. When the content of the dichroic dye is within the above range, it may be more advantageous to display a black visual sensation close to neutral in all lateral directions.

The dye layer thickness may be, for example, in the range of 0.1㎛ to 20㎛. When the dye layer thickness is within the above range, the dichroic dye can be well aligned, so it can be more advantageous to display a black visual sensation close to neutral in all lateral directions.

In the present application, the in-plane retardation value can be defined by Equation 1 below, and the thickness direction retardation value can be defined by Equation 2 below.

[Formula 1]

Rin = (nx-ny) × d

[Formula 2]

Rth = (nz-ny) × d

In Equation 1, Rin refers to the in-plane retardation value, in Equation 2, Rth refers to the thickness direction retardation value, and nx, ny, and nz are the dye layer, liquid crystal layer, and quarter wave plate for a wavelength of 550 nm, respectively. , is the refractive index of the x-axis, y-axis and z-axis of the retardation layer such as a 1/2 wave plate or C plate, and d is the retardation layer such as a dye layer, liquid crystal layer, 1/4 wave plate, 1/2 wave plate or C plate. is the thickness of the layer.

In this application, the x-axis, y-axis, and z-axis of the dye layer, liquid crystal layer, and retardation layer are described, and unless otherwise specified, the x-axis is the dye layer, liquid crystal layer, 1/4 wave plate, 1/2 wave plate, or C It refers to a direction parallel to the in-plane slow axis of a retardation layer such as a plate, and the y-axis is parallel to the in-plane fast axis of a retardation layer such as a dye layer, liquid crystal layer, 1/4 wave plate, 1/2 wave plate, or C plate. It refers to the direction, and the z-axis refers to the thickness direction of the retardation layer such as a dye layer, liquid crystal layer, 1/4 wave plate, 1/2 wave plate, or C plate. The x-axis and y-axis may be perpendicular to each other in the plane. In the present application, when the dye layer, liquid crystal layer, or retardation layer includes a rod-shaped liquid crystal compound, the slow axis may refer to the long axis direction of the rod-shaped liquid crystal compound, and if the dye layer, liquid crystal layer, or retardation layer includes a disk-shaped liquid crystal compound, the slow axis may refer to the normal line of the disk shape. It can mean direction. In this application, when describing the optical axis of a retardation layer such as a dye layer, liquid crystal layer, 1/4 wave plate, 1/2 wave plate, or C plate, unless otherwise specified, it means the slow axis. In this application, unless specifically specified otherwise while describing the refractive index of the dye layer, liquid crystal layer, or retardation layer such as 1/4 wave plate, 1/2 wave plate, or C plate, it refers to the refractive index for light with a wavelength of about 550 nm. do.

The dye layer may exhibit a specific transmittance from the front and sides by including a dichroic dye in a vertically oriented state. Through this, it can be advantageous to display a black visual sensation close to neutral from all sides. The dye layer may have a transmittance ratio of Ts(50°)/Ts(0°) ((100×T(50°)/T(0°)) of 80% or less. The lower limit of the transmittance ratio is, for example, , may be 45% or more or 50% or more. In the above, Ts (0°) is the average transmittance for a wavelength of 380 nm to 780 nm measured in front of the dye layer, and Ts (50°) is based on the 50° inclination angle of the dye layer. It may mean the average transmittance for a wavelength of 380 nm to 780 nm, measured at an azimuth of 0° to 360°. At this time, the Ts (0°) value of the dye layer is 40% or more, 50% or more, 60% or more, or It may be 70% or more. The upper limit of the Ts(0°) value may be, for example, 90% or less.

The dye layer can be formed, for example, by applying a composition containing a liquid crystal compound and a dichroic dye to one surface of the base layer and then curing or polymerizing the composition.

The coating method of the composition on the base layer is not particularly limited, and includes known coating methods such as roll coating, printing method, inkjet coating, slit nozzle method, bar coating, comma coating, spin coating, or gravure coating. It can be performed by coating through.

The polymerization method of the composition is not particularly limited and may be performed by a known liquid crystal compound polymerization method. For example, the polymerization reaction can be initiated by maintaining an appropriate temperature or by irradiating appropriate active energy rays. When maintenance at an appropriate temperature and irradiation of active energy rays are required simultaneously, the above processes may be carried out sequentially or simultaneously. In the above, irradiation of active energy rays can be performed using, for example, a high-pressure mercury lamp, an electrodeless lamp, or a xenon lamp, and the conditions such as wavelength, luminous intensity, or amount of irradiated active energy rays are as described above. It may be selected within a range that allows proper polymerization of the polymerizable liquid crystal compound.

As the base layer, known materials can be used without particular restrictions. For example, inorganic films such as glass films, crystalline or non-crystalline silicon films, quartz or ITO (Indium Tin Oxide) films, or plastic films can be used. As the base layer, an optically isotropic base layer or an optically anisotropic base layer such as a retardation layer can be used. Plastic films include TAC (triacetyl cellulose); COP (cyclo olefin copolymer) such as norbornene derivatives; PMMA (poly(methyl methacrylate); PC(polycarbonate); PE(polyethylene); PP(polypropylene); PVA(polyvinyl alcohol); DAC(diacetyl cellulose); Pac(Polyacrylate); PES(poly ether sulfone); PEEK(polyetheretherketone) ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate); or a base layer containing an amorphous fluororesin can be used. It is not limited to this. If necessary, the base layer may include a coating layer of a silicon compound such as gold, silver, silicon dioxide, or silicon monoxide, or a coating layer such as an anti-reflection layer.

A vertical alignment layer may be formed on the base layer to vertically align the liquid crystal compound. As the alignment layer, for example, an alignment layer known to be a contact type alignment layer such as a rubbing alignment layer or a photo-alignment layer compound and capable of exhibiting alignment characteristics by a non-contact method such as irradiation of linearly polarized light can be used. You can.

The retardation layer may be disposed on a side opposite to the dye layer of the polarizer. The retardation layer may include at least a quarter wave plate. The 1/4 wave plate may have an in-plane retardation value in the range of 100 nm to 180 nm or 100 nm to 150 nm. The 1/4 wave plate refers to a phase difference layer with 1/4 wave phase retardation characteristics. In this application, the term n-wavelength phase retardation characteristic refers to a characteristic that can retard the phase of incident light by n times the wavelength of the incident light, within at least some wavelength range. The 1/4 wavelength phase retardation characteristic may be a characteristic that converts incident linearly polarized light into elliptically polarized light or circularly polarized light, and conversely converts incident elliptically polarized light or circularly polarized light into linearly polarized light. A phase difference layer with a 1/4 wavelength phase retardation characteristic can be applied to the OLED panel to prevent reflection of external light, creating a black visual experience when the power is off.

The quarter wave plate may be a liquid crystal film or a polymer film. In the case of a liquid crystal film, it can be manufactured by including a polymerizable or curable liquid crystal compound in a polymerized or cured state. In the case of polymer films, polymer films include, for example, polyolefin films such as polyethylene films or polypropylene films, cyclic olefin polymer (COP: Cycloolefin polymer) films such as polynorbornene films, polyvinyl chloride films, and polyacrylic films. Examples include cellulose ester-based polymer films such as nitrile films, polysulfone films, polyacrylate films, polyvinyl alcohol films, or TAC (Triacetyl cellulose) films, and copolymer films of two or more types of monomers among the monomers forming the polymers. You can.

The polarizing plate of the present application may be more advantageous in improving lateral omnidirectional reflection characteristics by including at least the quarter wave plate as a retardation layer and further including another retardation film. When the retardation layer has a multi-layer structure, each layer may be attached via a pressure sensitive adhesive or adhesive, or may be laminated on each other by direct coating.

In one example, as shown in FIG. 2, the retardation layer may further include a C plate 400 on one side of the quarter wave plate 300. The C plate may be placed on the side opposite to the polarizer of the quarter wave plate.

In the present specification, the C plate may refer to a retardation layer having a thickness direction retardation value greater than 0 nm and a plane direction retardation value within the range of -10 nm to 10 nm, -5 nm to 5 nm, and -1 nm to 1 nm. For example, the thickness direction retardation value of the C plate may be in the range of 20 nm to 200 nm. Within this range, it may be more advantageous to improve side omnidirectional reflection visibility.

The C plate may include a vertically aligned liquid crystal compound. Regarding the liquid crystal compound, the contents of the liquid crystal compound described in the section on the dye layer can be applied in the same way. However, the C plate differs from the dye layer in that it does not contain dichroic dye. As will be described later when the C plate contains a dichroic dye, when a polarizer is applied to an OLED panel, the dichroic dye layer is disposed between the polarizer and the OLED panel, thereby increasing the reflectance at the viewing angle. Therefore, the C plate located inside the polarizer does not contain dichroic dye.

When the polarizer further includes a C plate, the angle between the slow axis of the quarter wave plate and the absorption axis of the polarizer may be in the range of 40 degrees to 50 degrees. Through this, excellent reflective properties can be obtained not only from the front but also from the sides.

When the polarizer further includes a C plate, the quarter wave plate may satisfy Equation 3 below. The polarizing plate of the present application may be advantageous in obtaining excellent reflection characteristics not only from the front but also from the side within the dispersion value range of Equation 3 below.

[Formula 3]

0.6 < R(450)/R(550) < 1.2

In Equation 3, R(λ) is the in-plane retardation value for the λnm wavelength of the 1/4 wave plate.

The R(450)/R(550) value may specifically be 0.60 or more, 0.65 or more, 0.70 or more, 0.75 or more, 0.80 or more, or 0.85 or more, and may be 1.20 or less, 1.15 or less, 1.10 or less, or 1.05 or less.

R(650)/R(550) of the 1/4 wave plate can be appropriately selected considering the desired dispersion characteristics. In general, if the following general formula 1 is satisfied, it can be called an inverse dispersion characteristic, if the general formula 2 is satisfied, it can be called a normal dispersion characteristic, and if the general formula 3 is satisfied, it can be called a flat dispersion characteristic.

[General Formula 1]

R(450)/R(550) < R(650)/R(450)

[General Formula 2]

R(450)/R(550) > R(650)/R(450)

[General Formula 3]

R(450)/R(550)≒ R(650)/R(450)

In General Formulas 1 to 3, R(λ) is the in-plane retardation value for the λnm wavelength of the 1/4 wave plate.

The quarter wave plate may have inverse dispersion characteristics, positive dispersion characteristics, or flat dispersion characteristics. In one example, if the quarter wave plate has inverse dispersion characteristics, it may be more advantageous to obtain excellent reflection characteristics not only from the front but also from the side.

In the present specification, the phase difference layer having inverse dispersion characteristics may have R(450)/R(550) of 0.60 or more, 0.65 or more, 0.70 or more, 0.75 or more, 0.80 or more, or 0.85 or more, and the upper limit may be 0.99 or less, 0.95 or less, or It may be less than 0.92. In the phase difference layer having the inverse dispersion characteristic, the value of R(650)/R(550) may be 1.01 or more, and the upper limit may be 1.2 or less, 1.15 or less, 1.10 or less, or 1.05 or less.

In the present specification, the phase difference layer having positive dispersion characteristics, R (450) / R (550) is 1.01 to 1.19, 1.02 to 1.18, 1.03 to 1.17, 1.04 to 1.16, 1.05 to 1.15, 1.06 to 1.14, 1.07 to 1.13 or It may be 1.08 to 1.12, and R(650)/R(550) may be about 0.81 to 0.99, 0.82 to 0.98, 0.83 to 0.97, 0.84 to 0.96, 0.85 to 0.95, or 0.86 to 0.94.

In the present specification, the phase difference layer with flat dispersion characteristics has a difference between R (450) / R (550) and R (650) / R (550) within 1, within 0.7, within 0.5, within 0.2, within 0.1 or substantially. It can be 0. In one example, the phase difference layer having the flat dispersion characteristic may have R(450)/R(550) of 0.99 to 1.01 and R(650)/R(550) of 0.99 to 1.01.

In another example, as shown in FIG. 3, the retardation layer may further include a 1/2 wave plate 500 on one side of the 1/4 wave plate 300. The 1/2 wave plate may be placed on the side facing the polarizer of the 1/4 wave plate. The 1/2 wave plate may have an in-plane retardation value in the range of 220 nm to 300 nm for a wavelength of 550 nm.

In the example of FIG. 3, the quarter wave plate and the half wave plate may each independently have reverse wavelength dispersion characteristics, forward wavelength dispersion characteristics, or flat wavelength dispersion characteristics. The dispersion value of R(450)/(550) to R(650)/(550) of the dispersion characteristic may be within the above-mentioned range.

In one example, one of the 1/4 wave plate and the 1/2 wave plate is a liquid crystal layer containing a calamitic liquid crystal compound, and the other is a liquid crystal layer containing a discotic liquid crystal compound. You can. The slow axis of the liquid crystal layer containing the calamitic liquid crystal compound may be 10 to 30 degrees from the absorption axis of the polarizer, and the slow axis of the liquid crystal layer containing the discotic liquid crystal compound may be 60 degrees from the absorption axis of the polarizer. It can be from 1 to 90 degrees. Within this angular range, the entire phase difference layer exhibits the inverse dispersion characteristic of Equation 3 and can be advantageous in exhibiting λ/4 phase retardation characteristics.

The dye layer, polarizer, 1/4 wave plate, 1/2 wave plate to C plate of the polarizer may be attached to each other through an adhesive or adhesive, or may be laminated to each other by direct coating. An optically transparent adhesive or adhesive may be used as the adhesive or adhesive.

Since the polarizing plate of the present application can prevent reflection of external light, visibility of the organic light emitting display device can be improved. Incident unpolarized light (hereinafter referred to as “extraneous light”) incident from the outside passes through the polarizer, and only one polarization orthogonal component out of the two polarization orthogonal components, that is, the first polarization orthogonal component, is transmitted, and the polarized light is transmitted. The light may be converted into circularly polarized light while passing through the first retardation film. As the circularly polarized light is reflected from the organic light emitting display panel including the substrate and electrode, the rotation direction of the circularly polarized light changes, and as the circularly polarized light passes again through the retardation layer including at least the quarter wave plate, two Another one of the two polarization orthogonal components is converted into a second polarization orthogonal component. Since the second polarization orthogonal component does not pass through the polarizer and thus light is not emitted to the outside, it may have an effect of preventing reflection of external light.

The polarizer of the present application can effectively prevent reflection of external light incident from the side, thereby improving side visibility of the organic light emitting display device. For example, reflection of external light incident from the side can be effectively prevented through the viewing angle polarization compensation principle.

The polarizer of the present application can be applied to an organic light emitting display device. Figure 4 is a cross-sectional view illustrating an organic light emitting display device to which the optical filter of the present application is applied. Referring to FIG. 4 , the organic light emitting device may include an organic light emitting display panel and a polarizing plate disposed on one side of the organic light emitting display panel, and a quarter wave plate 300 of the polarizing plate is applied to the dye layer 200. In comparison, it can be placed closer to the organic light emitting display panel 600.

The organic light emitting display panel may include a base substrate, a lower electrode, an organic light emitting layer, an upper electrode, and an encapsulation substrate. 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 can be made of a conductive material with a high work function, and the cathode is an electrode into which electrons are injected and can be made of a conductive material with 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 can exit, for example, ITO or IZO. The organic light-emitting layer may include an organic material that can emit light when voltage is applied to the lower electrode and the upper electrode.

An auxiliary layer may be further included between the lower electrode and the organic light-emitting layer and between the upper electrode and the organic light-emitting layer. The auxiliary layer may include a hole transporting layer, a hole injecting layer, an electron injecting layer, and an electron transporting layer to balance electrons and holes. However, it is not limited to this. The encapsulation substrate may be made of glass, metal, and/or polymer, and can prevent moisture and/or oxygen from entering from the outside by encapsulating the lower electrode, organic light-emitting layer, and upper electrode.

The polarizer may be placed on the side where light comes from in the organic light emitting display panel. For example, in the case of a bottom emission structure where light emits toward the base substrate, it can be placed outside the base substrate, and in the case of a top emission structure where light emits toward the encapsulation substrate, it can be placed outside the encapsulation substrate. there is. A polarizer can improve the display characteristics of an organic light emitting device by preventing external light from being reflected by a reflective layer made of metal, such as electrodes and wiring of an organic light emitting display panel, and exiting the organic light emitting device. Additionally, as described above, the polarizer can exhibit an anti-reflection effect not only from the front but also from the side, thereby improving side visibility.

By applying the polarizing plate of the present application, the organic light emitting display device can achieve a uniform, near-neutral black perspective in all lateral directions, thereby improving viewing angle reflection characteristics. The method of constructing the organic light emitting display device as described above is not particularly limited, and any conventional method may be applied as long as the polarizer is used.

This application relates to polarizers and uses of polarizers. The polarizer of the present application not only has excellent anti-reflection performance, but can also achieve a black visual sensation close to neutral in all directions on the side. The polarizing plate of the present application can be applied to an organic light emitting display device to improve viewing angle reflection characteristics.

Figure 1 exemplarily shows a polarizing plate of the present application.
Figure 2 exemplarily shows a polarizer of the present application.
Figure 3 exemplarily shows a polarizer of the present application.
Figure 4 exemplarily shows an organic light emitting display device of the present application.
Figure 5 shows the transmittance measurement results of Measurement Example 1.
Figure 6 is a graph to explain the color area.
Figure 7 shows the color coordinate measurement results of Comparative Examples 1 to 2 and Examples 1 to 9.
Figure 8 shows the color coordinate measurement results of Comparative Examples 3 to 4 and Examples 10 to 18.

Hereinafter, the present application will be described in detail 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 1 to 9

To evaluate reflection characteristics, a polarizer including a dichroic dye layer, a polarizer, a quarter wave plate, and a C plate in that order was prepared.

The polarizer has an absorption axis in one direction and has a single transmittance (Ts) of 42.5%.

The dichroic dye layer includes a calamitic liquid crystal compound and a dichroic dye in a vertically aligned state, and has a thickness of 0.7㎛. am. Examples 1 to 9 were prepared according to the dichroic ratio of the dichroic dye as shown in Table 1 below.

The quarter wave plate is a liquid crystal film with an in-plane retardation value of 140 nm for a wavelength of 550 nm, an R(450)/R(550) value of 0.86, and an R(650)/R(550) value of 1.02. The slow axis of the quarter wave plate is at an angle of 45 degrees clockwise with the absorption axis of the polarizer.

The C plate includes a calamitic liquid crystal compound in a vertically aligned state, and has a thickness direction retardation value of 70 nm for a wavelength of 550 nm.

Comparative example One

A polarizing plate was prepared in the same manner as Example 1 except that a TAC film was applied instead of the dichroic dye layer.

Comparative example 2

A polarizing plate was prepared in the same manner as in Example 1, except that an isotropic dye layer was applied instead of the dichroic dye layer.

Example 10 to 18

To evaluate reflection characteristics, a polarizer including a dichroic dye layer, a polarizer, a 1/2 wave plate, and a 1/4 wave plate in that order was prepared.

The polarizer has an absorption axis in one direction and has a single transmittance (Ts) of 42.5%.

The dichroic dye layer includes a calamitic liquid crystal compound and a dichroic dye in a vertically aligned state, and has a thickness of 0.7㎛. Examples 10 to 18 were prepared according to the dichroic ratio of the dichroic dye as shown in Table 2 below.

The 1/2 wave plate includes a discotic liquid crystal compound in a horizontal orientation, and has an in-plane retardation value of 240 nm for a wavelength of 550 nm. The slow axis of the 1/2 wave plate is 75 degrees clockwise with the absorption axis of the polarizer.

The quarter wave plate includes a calamitic liquid crystal compound in a horizontal orientation, and has an in-plane retardation value of 120 nm for a wavelength of 550 nm. The slow axis of the 1/2 wave plate is 15 degrees clockwise from the absorption axis of the polarizer.

Comparative example 3

A polarizing plate was prepared in the same manner as Example 10, except that a TAC film was applied instead of the dichroic dye layer.

Comparative example 4

A polarizing plate was prepared in the same manner as Example 10, except that an isotropic dye layer was applied instead of the dichroic dye layer.

Comparative example 5 to 13

In Examples 1 to 9, polarizer plates were prepared in the same manner as Examples 1 to 9, except that the arrangement order of the polarizer was changed to the order of polarizer, dichroic dye layer, quarter wave plate, and C plate.

Measurement example One. dichroism dye layer Transmittance characteristics such as

The single transmittance of the TAC layer used in Comparative Examples 1 and 3, the isotropic dye layer used in Comparative Examples 2 and 4, and the dichroic dye layer according to the dichroic ratio used in Examples 1 to 18 were measured (Axometrics Axoscan), and the results are shown in Tables 1 and 2 and Figure 5. The transmittance is the average transmittance for wavelengths from 380 nm to 780 nm. In Tables 1 and 2, Ts(0°) is the average transmittance for a wavelength of 380 nm to 780 nm measured in front of the layer, and Ts(50°) is an azimuth of 0° to 360° based on a 50° tilt angle of the layer. It means the average transmittance for wavelengths from 380 nm to 780 nm, measured in . Ts(50°)/Ts(0°) is the ratio of Ts(50°) to Ts(0°). Tables 1 and 2 list the Ts(50°)/Ts(0°)×100 values. The dichroic ratio of the dichroic dye can be predicted from the value of Ts(50°)/Ts(0°)×100, and in Example 1, the above value is about 78.3%, from which the dichroic ratio is expected to be about 5 You can.

Test example 1. Evaluation of frontal characteristics

The polarizers of Examples and Comparative Examples were attached to an OLED panel (55% reflectance for a 550 nm wavelength) so that the 1/4 wave plate was closer to the OLED panel than the polarizer, and then the luminance and reflectance were measured from the front. The results are shown in Tables 1 and 2. Brightness was measured using TOPCON's SR-UL2 equipment. Reflectance was measured using Konica Minolta's CM-2600D equipment. The reflectance is the average reflectance for wavelengths from 380 nm to 780 nm. The luminance is based on 100% of the luminance value of Comparative Example 1. Reflectance is based on 100% White Standard (standard sample - Calibrator).

Test example 2. Evaluation of side characteristics

The polarizers of examples and comparative examples were attached to an OLED panel (55% reflectance for a 550 nm wavelength) so that the 1/4 wave plate was closer to the OLED panel than the polarizer, and then the color area and dE were measured from the side (50°). max was measured, and the results are shown in Tables 1 and 2. Color area and dE max were measured using Eldim's EZContrast MS-80 equipment.

The color area plots a ^* b ^* color coordinates at 5-degree intervals at azimuth angles of 0 degrees to 360 degrees based on an inclination angle of 50 degrees, then sets the maximum and minimum values of a ^* as the vertical sides, and b ^* It is defined as the area of a rectangle (e.g., the rectangle in FIG. 6) with the maximum and minimum values as horizontal sides. The smaller the color area, the more uniform the color of reflection in all directions from the side. Figures 7 and 8 show a*b* color coordinate plot results, respectively.

dE max is defined as the maximum value among the following color deviation (ΔE ^* _ab ) values measured at 5-degree intervals at azimuth angles of 0 degrees to 360 degrees based on an inclination angle of 50 degrees.

In the above formula, (L ^* ₁ ,a ^* ₁ ,b ^* ₁ ) means the reflected color value at the front (tilt angle 0°, azimuth angle 0°), and (L ^* ₂ ,a ^* ₂ ,b ^* ₂ ) means This refers to the reflected color value from the side (specific inclination and azimuth angles). The smaller the de max value, the more uniform the color of reflection in all directions from the side.

heterogeneous ratio Transmittance characteristics frontal characteristics Lateral characteristics (50°) Ts(0°) Ts(50°)/Ts(0°) Luminance reflectivity Color area dE max Comparative Example 1 - 91.4 96.6 100.0 4.25 2.08 6.78 Comparative Example 2 0 70.4 85.5 76.2 4.12 0.69 6.06 Example 1 5 71.3 78.3 77.3 4.14 0.40 5.48 Example 2 10 79.7 13.4 86.4 4.18 0.41 5.47 Example 3 20 85.5 67.5 92.7 4.22 0.33 5.44 Example 4 30 87.7 63.1 95.1 4.23 0.30 5.41 Example 5 40 88.6 59.5 96.0 4.24 0.28 5.38 Example 6 50 88.9 56.6 96.4 4.24 0.26 5.36 Example 7 60 89.0 54.5 96.5 4.24 0.24 0.34 Example 8 70 89.0 53.0 96.5 4.24 0.23 5.33 Example 9 88 88.9 51.6 96.5 4.25 0.21 5.32

heterogeneous ratio Transmittance characteristics frontal characteristics Lateral characteristics (50°) Ts(0°) Ts(50°)/Ts(0°) Luminance reflectivity Color area dE max Comparative Example 3 - 91.4 96.6 103.9 4.25 28.67 8.65 Comparative Example 4 0 70.4 85.5 79.2 4.13 5.07 6.70 Example 10 5 71.3 78.3 80.3 4.14 3.85 5.81 Example 11 10 79.7 13.4 89.8 4.19 4.76 5.79 Example 12 20 85.5 67.5 96.4 4.22 4.34 5.82 Example 13 30 87.7 63.1 98.8 4.24 3.53 5.84 Example 14 40 88.6 59.5 99.8 4.24 2.89 5.83 Example 15 50 88.9 56.6 100.2 4.25 2.57 5.82 Example 16 60 89.0 54.5 100.3 4.25 2.45 5.80 Example 17 70 89.0 53.0 100.3 4.25 2.37 5.78 Example 18 88 88.9 51.6 100.3 4.25 2.30 5.74

This unique ratio Transmittance characteristics frontal characteristics Lateral characteristics (50°) Ts(0°) Ts(50°)/Ts(0°) Luminance reflectivity
(%) Color area dE max Comparative Example 5 5 71.3 78.3 77.0 4.14 7.05 7.11 Comparative Example 6 10 79.7 13.4 86.2 4.18 10.41 7.80 Comparative Example 7 20 85.5 67.5 92.3 4.21 15.33 8,92 Comparative Example 8 30 87.7 63.1 95.3 4.22 21.96 10.12 Comparative Example 9 40 88.6 59.5 96.1 4.22 29.13 11.40 Comparative Example 10 50 88.9 56.6 96.3 4.22 36.61 12.74 Comparative Example 11 60 89.0 54.5 96.5 4.22 43.36 14.05 Comparative Example 12 70 89.0 53.0 96.5 4.22 49.98 15.27 Comparative Example 13 88 88.9 51.6 96.5 4.22 61.17 17.18

100: Polarizer, 200: Dye layer, 300: 1/4 wave plate, 400: C plate, 500: 1/2 wave plate, 600: Organic light emitting display panel.

Claims (15)

Comprising an organic light emitting display panel and a polarizing plate disposed on one side of the organic light emitting display panel,
The polarizing plate includes a polarizer, a dye layer disposed on one side of the polarizer and including a liquid crystal compound and a dichroic dye in a vertically aligned state, and a retardation layer disposed on a side opposite to the dye layer of the polarizer,
The retardation layer includes a 1/4 wave plate having an in-plane retardation value in the range of 100 nm to 180 nm in Equation 1 below, and a C plate disposed on a side opposite to the polarizer of the 1/4 wave plate,
The dye layer has a transmittance ratio of Ts(50°)/Ts(0°) ((100×T(50°)/T(0°)) of 80% or less, and the Ts(0°) value of the dye layer is 80% or less. is 40% or more, where Ts (0°) is the average transmittance for a wavelength of 380 nm to 780 nm measured in front of the dye layer, and Ts (50°) is 0° to 0° based on the 50° inclination angle of the dye layer. Means the average transmittance for wavelengths from 380 nm to 780 nm, measured at 360° azimuth,
A quarter wave plate of the polarizer is disposed closer to the organic light emitting display panel than the dye layer,
The dichroic ratio of the dichroic dye is in the range of 20 to 100,
The C plate does not contain a dichroic dye, and the organic light emitting display device has a thickness direction retardation value in the range of 20 nm to 200 nm in Equation 2 below:
[Formula 1]
Rin = (nx-ny) × d
In Equation 1, Rin means the in-plane retardation value, nx and ny are the refractive indices of the x-axis and y-axis of the quarter wave plate for a wavelength of 550 nm, respectively, and d is the thickness of the quarter wave plate.
[Formula 2]
Rth = (nz-ny) × d
In Equation 2, Rth means the thickness direction retardation value, ny and nz are the refractive indices of the y-axis and z-axis of the C plate for a wavelength of 550 nm, respectively, and d is the thickness of the C plate. The organic light emitting display device of claim 1, wherein the dye layer includes a liquid crystal compound in a cured state. The organic light emitting display device of claim 1, wherein the dye layer has a thickness in the range of 0.1 ㎛ to 20 ㎛. delete The organic light emitting display device of claim 1, wherein the dichroic dye is included in the dye layer in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the liquid crystal compound. delete delete delete delete The organic light emitting display device of claim 1, wherein the quarter wave plate satisfies Equation 3 below:
[Formula 3]
0.6 < R(450)/R(550) < 1.2
In Equation 3, R(λ) is the in-plane retardation value of the 1/4 wave plate for the λnm wavelength. The organic light emitting display device of claim 1, wherein an angle between the slow axis of the quarter wave plate and the absorption axis of the polarizer is within a range of 40 degrees to 50 degrees. delete delete delete delete

Images