KR20210028876A - Circularly polarizing plate - Google Patents

Abstract

The present application relates to a circularly polarizing plate. The present application provides the circularly polarizing plate, which uses a retardation film having reverse dispersion characteristics to neutralize the reflected color of an OLED panel, so as to improve reflective luminance, and an OLED device including the circularly polarizing plate.

Description

Circularly polarizing plate

This application relates to a circularly polarizing plate.

A so-called circularly polarizing plate that basically includes a polarizer and a retardation film can be used to lower surface reflection in the Off state of the OLED panel. For example, Patent Document 1 discloses a method of arranging a circularly polarizing plate on the side of a transparent electrode in an organic light emitting device.

Japanese Patent Laid-Open No. Hei 8-321381

The present application provides a circularly polarizing plate capable of improving reflective color by using a retardation film having reverse dispersion characteristics, and an OLED device including the circularly polarizing plate.

This application relates to a circularly polarizing plate. 1 shows an exemplary circularly polarizing plate of the present application. As shown in FIG. 1, the circularly polarizing plate 100 of the present application may sequentially include an antireflection film 10, a polarizer 20, a retardation film 30, and an adhesive layer 40. The retardation film may have reverse dispersion characteristics. In the circularly polarizing plate, the retardation film may have a Rin(450)/Rin(550) value of 0.9 or more to less than 1, and the lowest reflection wavelength of the antireflection film may be 520 nm or less.

The present application can improve the reflection visibility by neutralizing the reflection color of the OLED panel through such a circular polarizing plate. Hereinafter, the circularly polarizing plate of the present application will be described in detail.

The reflectance of the antireflection film may be adjusted within a range such that the reflectance measured with the circularly polarizing plate attached to an OLED panel to be described later is about 1.5% or less. The reflectance of the antireflection film for a wavelength of 550 nm may be in the range of 0.6% to 1.2% or 0.6% to 1.0%. In addition, the reflectance of the antireflection film for a wavelength of 430 nm may also be in the range of 0.6% to 1.2% or 0.6% to 1.0%.

Transmittance of the antireflection film to light having a wavelength of 380 nm to 780 nm may be 90% or more or 95% or more. The haze of the antireflection film may be 1% or less.

^{The anti-reflection film may satisfy L *} a ^* b ^* color coordinate criteria b ^* >-4 determined according to the method defined in CIE 1976. b ^* may be specifically -3 or more, -2.5 or more, 0.05 or more, and its upper limit may be 10 or less, 8 or less, or 6 or less.

^{The anti-reflection film may satisfy L *} a ^* b ^* color coordinate criteria a ^* >0 determined according to the method defined in CIE 1976. Specifically, a ^* may be 0.5 or more, 1 or more, 1.5 or more, or 2 or more, and the upper limit thereof may be, for example, 5 or less.

The antireflection film may satisfy ^{a *} <b ^* or a ^* >b ^*. In one example, when the reflection color of the antireflection film ^{satisfies b *} ≥ 2.0, a ^* <b ^* can be satisfied. In another example, when the reflection color of the antireflection film ^{satisfies b *} <2.0, a ^* <b ^* may be satisfied. In addition, the anti-reflection film may ^{satisfy a reflection color of 0.5 <L *} <13. The L ^* may specifically be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, and may be 13 or less, 12 or less, 11 or less, 10 or less, or 9 or less. By neutralizing the reflective color of the OLED panel through the use of such an antireflection film, it may be more advantageous in improving the reflective visibility.

The antireflection film may have a minimum reflection wavelength of 520 nm or less. In the present specification, the lowest reflection wavelength may mean a wavelength at a point at which the reflectance is the lowest in the reflectance spectrum with respect to the wavelength of the antireflection film. The lowest reflection wavelength may be, for example, 390 nm or more, 395 nm or more, 400 nm or more, 405 nm or more, 410 nm or more, 415 nm or more, or 420 nm or more. The antireflection film may have a minimum reflectance of 1.0% or less. In the present specification, the lowest reflectance may mean a reflectance at a point at which reflectance is the lowest in the reflectance spectrum for the wavelength of the antireflection film.

The anti-reflection film may exhibit a U-shaped graph of a reflectance spectrum with respect to a wavelength. Fig. 2(a) exemplarily shows a U-shaped graph, and Fig. 2(b) exemplarily shows a W-shaped graph. FIG. 2 is a diagram for explaining a U-shaped graph as an example, and the scope of the present application is not limited to FIG. 2. The antireflection film may have one reflection band showing the lowest reflectance within a wavelength range of 380 nm to 780 nm, for example, a wavelength band having a reflectance of 1% or less (region R1 in FIG. 2(a)). Such a U-shaped graph may be a concept distinguished from a W-shaped graph in which two areas (R1 and R2 in FIG. 2(b)) have reflection bands representing the lowest reflectance within a wavelength range of 380 nm to 780 nm. Through the use of such an anti-reflection film, it may be more advantageous to improve the reflective color by using a retardation film having a reverse dispersion characteristic in which Rin (450) / Rin (550) values are above a certain level.

When the optical properties of the antireflection film are within the above range, a material may be appropriately selected. For example, the antireflection film may include a low refractive index layer. It is known to adjust the optical properties of the antireflection film within the above range. For example, the lowest reflection wavelength of the antireflection film tends to move to a longer wavelength as the thickness of the low refractive index layer is increased, and tend to move to a shorter wavelength as the thickness of the low refractive index layer is decreased. In addition, the lowest reflectivity of the antireflection film may be determined by a low refractive index material. For example, the lowest reflectivity of the antireflection film tends to decrease as the refractive index of the low refractive material decreases.

The low refractive layer may include a low refractive material. In one example, the low refractive material may be a low refractive inorganic particle. The low refractive inorganic particles may have a refractive index with respect to a wavelength of 550 nm, for example, 1.5 or less, 1.45 or less, or 1.40 or less. The lower limit of the refractive index may be, for example, 1.0 or more, 1.1 or more, 1.2 or more, or 1.3 or more.

In one example, the low refractive inorganic particles may be silica-based particles. The silica-based particles may be, for example, hollow silica, mesoporous silica, or the like. In another example, magnesium fluoride (MgF ₂ ) may be used as the inorganic nanoparticle.

In one example, the low refractive inorganic particles may be nano-sized particles. The average particle diameter of the low refractive inorganic particles may be, for example, in the range of 10 nm to 700 nm, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm.

The thickness of the low refractive layer may be appropriately adjusted in consideration of the purpose of the present application. The thickness of the low refractive layer may be, for example, in the range of 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, 50 nm to 200 nm, or 100 nm to 200 nm. As described above, since the minimum reflection wavelength of the antireflection film can be adjusted according to the thickness of the low refractive layer, the thickness of the low refractive convex layer can be appropriately adjusted within the above range in consideration of the desired minimum reflection wavelength.

The low refractive layer may further include a binder resin. The low refractive inorganic particles may exist in a dispersed state in the binder resin.

The low refractive layer may include 30 to 600 parts by weight of low refractive inorganic particles relative to 100 parts by weight of the binder resin. Specifically, the low refractive inorganic particles may be included in a range of 30 to 500 parts by weight, 30 to 400 parts by weight, 30 to 300 parts by weight, 30 to 200 parts by weight, or 100 to 200 parts by weight based on 100 parts by weight of the binder resin. When the content of the low-refractive inorganic particles is excessive, reflectance may be increased, and surface irregularities may be excessively generated, thereby deteriorating surface properties such as scratch resistance and antifouling properties.

The binder resin may be, for example, a photopolymerizable compound. Specifically, the photopolymerizable compound may include a monomer or oligomer including a (meth)acrylate or vinyl group. More specifically, the photopolymerizable compound may include a monomer or oligomer including one or more, or two or more, or three or more (meth)acrylate or vinyl groups.

Specific examples of the monomer or oligomer including the (meth)acrylate include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate. )Acrylate, tripentaerythritol hepta(meth)acrylate, triethylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylic Rate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, butanediol dimethacrylate, hexaethyl methacrylate, butyl methacrylate, or a mixture of two or more thereof, or urethane-modified acrylate oligomer, epoxide Side acrylate oligomers, ether acrylate oligomers, dendritic acrylate oligomers, or mixtures of two or more thereof. At this time, the molecular weight of the oligomer is preferably 1,000 to 10,000.

Specific examples of the monomer or oligomer including the vinyl group may include divinylbenzene, styrene, or paramethylstyrene.

Meanwhile, the photopolymerizable compound may further include a fluorine-based (meth)acrylate-based monomer or oligomer in addition to the above-described monomer or oligomer. When the fluorine-based (meth)acrylate-based monomer or oligomer is further included, the weight ratio of the fluorine-based (meth)acrylate-based monomer or oligomer to the monomer or oligomer containing the (meth)acrylate or vinyl group is 0.1% to It can be 10%.

The antireflection film may further include a base layer, and a low refractive index layer may be formed on one surface of the base layer.

The base layer may include a light-transmitting resin. Therefore, the substrate layer may be a light-transmitting substrate. The base layer may have a transmittance of 90% or more for light having a wavelength of 380 nm to 780 nm, for example. The base layer may have a haze of 1% or less for light having a wavelength of 380 nm to 780 nm, for example. Through the use of such a base layer, it may be more advantageous to provide an antireflection film capable of lowering reflectance while maintaining high transmittance.

The base layer is in the group consisting of a triacetyl cellulose (TAC) film, a cycloolefin polymer film, a poly(meth)acrylate film, a polycarbonate film, a polynorbornene film, and a polyester film. It may include at least one selected. The thickness of the base layer may be 10 μm to 300 μm in consideration of productivity, etc., but is not limited thereto.

The low refractive layer may be prepared by coating and curing a composition for forming a low refractive layer on a substrate layer. The composition for forming a low refractive layer may include low refractive inorganic particles, and may further include a binder resin. As described later, when the hard coating layer is formed on the substrate layer, the low refractive index layer may be formed by coating and curing the composition for forming the low refractive index layer on the hard coating layer.

The method of coating the composition for forming the low refractive index layer is not particularly limited, and may be performed by a known coating method such as spin coating, bar coating, roll coating, gravure coating, or blade coating.

A method of curing the composition for forming the low refractive index layer is not particularly limited, and may be performed, for example, by irradiation of light or application of heat. Photocuring the composition for forming the low refractive index layer may be performed by irradiating ultraviolet or visible light having a wavelength of 200 nm to 400 nm. In addition, the exposure amount during light irradiation may be in the range of 100 mJ/cm 2 to 4,000 mJ/cm 2. The exposure time is also not particularly limited, and can be appropriately changed according to the exposure apparatus used, the wavelength of the irradiated light, or the amount of exposure.

The antireflection film may further include a hard coating layer. The hard coating layer may exist between the base layer and the low refractive layer. The hard coating layer can improve the hardness of the antireflection film. Through this, the anti-reflection film can be used as an optical film, that is, a window film positioned on the outermost side of the display device.

The refractive index range of the hard coating layer may be appropriately selected within a range that does not impair the purpose of the present application. The hard coating layer may have, for example, a refractive index for a wavelength of 550 nm of 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, or 1.5 or less. The lower limit of the refractive index may be, for example, 1.0 or more, 1.1 or more, or 1.2 or more.

As the hard coating layer, a commonly known hard coating layer may be used without great limitation. The hard coating layer may include, for example, a photocurable resin. The photocurable resin may be a light-transmitting resin. The photocurable resin included in the hard coating layer is a polymer of a photocurable compound capable of causing a polymerization reaction when light such as ultraviolet rays is irradiated, and may be conventional in the art. Specifically, the photocurable resin is a reactive acrylate oligomer group consisting of urethane acrylate oligomer, epoxide acrylate oligomer, polyester acrylate, and polyether acrylate; And dipentaerythritol hexaacrylate, dipentaerythritol hydroxy pentaacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylene propyl triacrylate, propoxylated glycerol triacrylate, trimethylpropane ethoxy tri At least one selected from the group of polyfunctional acrylate monomers consisting of acrylate, 1,6-hexanediol diacrylate, propoxylated glycero triacrylate, tripropylene glycol diacrylate, and ethylene glycol diacrylate It may include.

The hard coating layer may further include organic or inorganic fine particles dispersed in the photocurable resin. In addition, a specific example of the organic or inorganic fine particles included in the hard coating layer is not limited, for example, the organic or inorganic fine particles are organic fine particles composed of an acrylic resin, a styrene resin, an epoxide resin, and a nylon resin, or silicon oxide, It may be inorganic fine particles composed of titanium dioxide, indium oxide, tin oxide, zirconium oxide and zinc oxide. The organic or inorganic fine particles are not specifically limited in particle diameter, for example, the organic fine particles may have a particle diameter of 1 to 10 µm, and the inorganic particles may have a particle diameter of 1 nm to 500 nm, or 1 nm to 300 nm. I can have it. The particle diameter of the organic or inorganic fine particles may be defined as a volume average particle diameter.

The hard coating layer may have a thickness of 0.1 μm to 100 μm. The pencil hardness of the antireflection film to which the hard coating layer is applied may be, for example, 2H or more or 4H or more. Within this range, even when the antireflection film is used as the outermost window film of the display device, it may be advantageous to protect the transparent display device from the outside.

The hard coating layer may be prepared, for example, by coating and curing a composition for forming a hard coating layer on a substrate layer. The composition for forming a hard coating layer may include the photocurable resin, and may further include organic or inorganic fine particles if necessary.

The method of curing the composition for forming the hard coating layer is not particularly limited, and may be performed, for example, by irradiation of light or application of heat. Photocuring the composition for forming the hard coating layer may be performed by irradiating ultraviolet or visible light having a wavelength of 200 nm to 400 nm. In addition, the exposure amount during light irradiation may be in the range of 100 mJ/cm 2 to 4,000 mJ/cm 2. The exposure time is also not particularly limited, and can be appropriately changed according to the exposure apparatus used, the wavelength of the irradiated light, or the amount of exposure.

The composition for forming the low refractive layer or the composition for forming the hard coating layer may further include a solvent. The solvent may be an organic solvent. As the organic solvent, a hydrocarbon-based, halogenated hydrocarbon-based, or ether-based solvent may be used. Examples of hydrocarbons include pentane, hexane, heptane, cyclohexane, n-decane, n-dodecane, benzene, toluene, xylene, and methoxybenzene. Examples of halogenated hydrocarbons include carbon tetrachloride, chloroform, 1,2-dichloroethane, dichloromethane, and chlorobenzene. Examples of the ether system include tetrahydrofuran, dioxane, and propylene glycol monomethyl ether acetate.

The composition for forming a low refractive index layer or the composition for forming a hard coating layer may further include an optional additive. Such additives include, for example, curing agents or catalysts that assist the curing of the curable resin, initiators such as radical initiators or cationic initiators, thixotropy imparting agents, leveling agents, antistatic agents, antifoaming agents, antioxidants, radical generating substances, presence or absence Group pigments, dyes, dispersants, various fillers such as thermally conductive fillers or insulating fillers, functional polymers, light stabilizers, etc. may be exemplified, but are not limited thereto.

In the present specification, the term polarizer means a film, sheet, or device having a polarizing function. The polarizer is a functional device capable of extracting light vibrating in one direction from incident light vibrating in various directions.

In the present specification, the terms polarizer and polarizer refer to objects that are distinguished from each other. The term polarizer means a film, sheet, or element itself having a polarizing function, and the term polarizing plate means an object including the polarizer and other elements laminated on one or both surfaces of the polarizing element. Other factors in the above may include, but are not limited to, a protective film of a polarizer, an antireflection film, a retardation film, an adhesive layer, an adhesive layer, and a surface treatment layer. According to the circular polarizing plate of the present application, a protective film attached to one or both sides of the polarizer may or may not be included. Even if a separate protective film attached to one or both sides of the polarizer is not included, an antireflection film and/or a retardation film may serve as a protective substrate for the polarizer.

As a polarizer in the present application, an absorption type linear polarizer may be used. As such a polarizer, a PVA (poly(vinyl alcohol)) polarizer is known. Basically, in the present application, a known polarizer may be used as the polarizer. In one example, as a known PVA (poly(vinyl alcohol)) polarizer, a polarizer having the following characteristics may be applied.

Transmittance of the polarizer for a wavelength of 550 nm may be in the range of 40% to 50%. Specifically, the transmittance may be in the range of 42% to 43% or 43.5% to 44.5%. The transmittance may mean a single transmittance of a polarizer for a wavelength of 550 nm. The single transmittance of the polarizer can be measured using, for example, a spectrometer (V7100, manufactured by Jasco). For example, with a polarizer sample (not including the upper and lower protective films) mounted on the device, air is set as the base line, and the transmittance of each polarizer sample is aligned vertically and horizontally with the axis of the reference polarizer. After measurement, the single transmittance can be calculated.

In general, a PVA (poly(vinyl alcohol))-based linear absorption polarizer exhibits the above single transmittance, and in this application, such a PVA-based linear absorption polarizer may be applied, but as long as it exhibits the above single transmittance, a polarizer that can be applied. The type of is not limited to the above.

The PVA polarizer generally includes a PVA film or sheet and an anisotropically absorbing material such as a dichroic dye or iodine adsorbed and oriented on the PVA film or sheet.

A PVA film or sheet can be obtained by gelling polyvinyl acetate, for example. As polyvinyl acetate, a homopolymer of vinyl acetate; And copolymers of vinyl acetate and other monomers. Other monomers copolymerized with vinyl acetate may include one or more types of 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 polyvinyl acetate 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 be generally about 1,000 to about 10,000 or about 1,500 to about 5,000.

The PVA polarizer is manufactured through a dyeing process and a stretching process to a PVA film or sheet. If necessary, the manufacturing process of the polarizer may further include swelling, crosslinking, washing and/or drying processes.

For example, the dyeing process in the above is a process for adsorbing iodine, which is an anisotropic absorbent material, to a PVA film or sheet, and can be performed by immersing the PVA film or sheet in a treatment bath containing iodine and potassium iodide. In the process, the single transmittance can be adjusted by controlling the concentrations of iodine and potassium iodide in the treatment tank.

In the dyeing process, the PVA film or sheet is _{immersed in a dyeing solution or crosslinking solution containing iodine (I 2} ), iodide such as KI and/or a boric acid compound (boric acid or borate), and in this process, anisotropic absorption of iodine, etc. The material is adsorbed onto the PVA film or sheet. Accordingly, in the above process, the type or amount of the anisotropic absorbing material adsorbed to the polarizer is determined according to the concentration of the compound in the dyeing solution, and accordingly, the absorption rate and transmittance of the polarizer for light of a specific wavelength may be determined.

For example, the species of an iodine compound which may be present in the staining solution is iodide might be a ^- a I derived from the iodine _{^{(I 2) -, I 2}} , I 3 - or I ₅ (M ⁺ I) have. By the way, in the compounds, I ⁻ has an absorption wavelength range of about 190 nm to 260 nm, color effect is not large, I ₂ has an absorption wavelength range of about 400 nm to 500 nm, and color is mainly red, I ₃ ^- is the absorption wavelength range of about 250 nm to 400 nm, the color is mainly yellow, and I ₅ ^- of the linear structure is not observed, the color effect is not large, and I of the curved structure ₅ ^- has an absorption wavelength range of about 500 nm to 900 nm, and the color is mainly blue.

The retardation film may have reverse dispersion characteristics. In the present specification, the inverse dispersion characteristic may mean a characteristic in which a retardation value increases as a wavelength increases. In the reverse dispersion characteristic, a value of Rin(450)/Rin(550) of the retardation film may be less than 1. The retardation film may have a Rin(450)/Rin(550) value of 0.9 or more. When a circularly polarizing plate including a retardation film having reverse dispersion characteristics is applied to an OLED panel, if the Rin(450)/Rin(550) value of the retardation film is low, for example, if it is less than 0.9, the reflective color is good, If the Rin (450) / Rin (550) value is higher than a certain level, for example, 0.9 or higher, the reflective color tends to be poor. According to the present invention, by controlling the transmittance of the lowest reflection wavelength of the antireflection film and the 430 nm wavelength of the circularly polarizing plate, even if a retardation film having a reverse dispersion characteristic having a Rin (450) / Rin (550) value of at least a certain level is used, By neutralizing the reflective color of the OLED panel, it is possible to improve the reflective visibility.

In addition, depending on the reverse dispersion characteristics, the value of Rin (650) / Rin (550) of the retardation film may be greater than 1 to 1.2 or less. In the above, Rin(λ) may mean an in-plane retardation value with respect to a λnm wavelength.

In the present specification, the in-plane retardation value may be calculated according to Equation 1 below, and the thickness direction retardation value may be calculated according to Equation 2 below.

[Equation 1]

Rin = d × (nx-ny)

[Equation 2]

Rth = d × [(nx + ny)/2-nz]

In Equations 1 and 2, Rin is the in-plane retardation, Rth is the retardation in the thickness direction, nx, ny, and nz are respectively the refractive index of the retardation film in the x-axis direction, the y-axis direction, and the z-axis direction, d Is the thickness of the retardation film. Unless otherwise specified, these definitions may be equally applied in the present specification. In the above, the x-axis direction means the in-plane slow axis direction of the retardation film, the y-axis direction means the in-plane direction (fast axis direction) perpendicular to the x-axis, and the z-axis direction is the x-axis and y-axis It may mean a direction of a normal to a plane formed by, for example, a thickness direction. In the present specification, the slow axis may mean an axis parallel to the direction in which the refractive index appears highest based on the plane direction of the retardation film. Unless otherwise specified while referring to the refractive index in the present specification, the refractive index is the refractive index for light having a wavelength of about 550 nm.

The in-plane retardation value for the 550 nm wavelength of the retardation film may be in the range of 130 nm to 150 nm, or 130 nm to 140 nm. The retardation value of the retardation film in the thickness direction with respect to the wavelength of 550 nm may be in the range of 65 nm to 140 nm. When the retardation value of the retardation film satisfies the above range, it may be advantageous in improving the reflective visibility by neutralizing the reflective color of the OLED panel.

The circularly polarizing plate, the retardation film the difference between four times the value (4Rin) and minimum reflection wavelength of the anti-reflection film (AR _min) of Rin (550) (4Rin - AR min) is at least 20 nm, at least 40 nm, 60 nm It may be at least 80 nm, at least 100 nm, at least 120 nm, at least 140 nm, or at least 150 nm. Through this, by neutralizing the reflective color of the OLED panel, it may be more advantageous to improve the reflective visibility. The upper limit of the difference (4Rin-AR _min ) may be, for example, 150 nm or less.

A method of adjusting an in-plane retardation value or a retardation value in the thickness direction of a retardation film is known. In one example, when the retardation film is a polymer stretched film, the retardation value may be adjusted by adjusting the material, thickness, and stretch ratio of the polymer film. In another example, when the retardation film is a liquid crystal polymerization film, the in-plane retardation value may be adjusted by adjusting the thickness of the liquid crystal layer and the birefringence value of the liquid crystal.

The angle formed by the slow axis of the retardation film and the absorption axis of the polarizer may be in the range of 40 degrees to 50 degrees, 43 degrees to 47 degrees, or 44 degrees to 46 degrees. Through this, by neutralizing the reflective color sense of the OLED panel, it may be advantageous to improve the reflective visibility.

The angle formed by the slow axis of the retardation film and the machine direction (MD) axis of the retardation film may be appropriately selected within a range such that the angle formed by the slow axis of the retardation film and the absorption axis of the polarizer satisfies the above range. In the present specification, the MD direction of the retardation film may mean the length direction of the retardation film. The slow axis of the retardation film and the MD axis of the retardation film may form an angle within a range of, for example, 0 degrees to 90 degrees. In one example, the slow axis of the retardation film and the MD axis of the retardation film may be parallel to each other, perpendicular to each other, or at an angle within a range of 40 degrees to 50 degrees, and according to an embodiment of the present application, 40 degrees to 50 degrees You can achieve an angle within the range. All. Through this, by neutralizing the reflective color sense of the OLED panel, it may be advantageous to improve the reflective visibility.

In the present specification, the angle formed by the A-axis with respect to the B-axis may be meant to include both an angle formed by the A-axis in a clockwise direction and an angle formed by the A-axis in a counterclockwise direction based on the B-axis at 0 degrees.

The thickness of the retardation film may be, for example, 10 μm to 100 μm in the case of a polymer stretched film. In another example, when the retardation film is a liquid crystal film, the thickness of the retardation film may be, for example, 0.1 µm to 5 µm.

The retardation film may be a liquid crystal polymer film or a polymer stretched film. Specifically, as the retardation film, a stretched polymer layer or a liquid crystal layer obtained by stretching a polymer film capable of imparting optical anisotropy by stretching in an appropriate manner may be used. As the liquid crystal layer, a liquid crystal polymer layer or a cured layer of a polymerizable liquid crystal compound can be used.

The liquid crystal polymerized film may include a substrate layer and a liquid crystal layer on one surface of the substrate layer. As for the base layer of the liquid crystal polymerized film, the contents of the base layer of the antireflection film may be equally applied. Therefore, a light-transmitting substrate can also be used for the substrate layer of the liquid crystal polymerized film. The liquid crystal layer may include a polymerizable liquid crystal compound in a polymerized state. In the present specification, the term "polymerizable liquid crystal compound" may mean a compound including a moiety capable of displaying liquid crystallinity, for example, a mesogen skeleton, and including at least one polymerizable functional group. . These polymerizable liquid crystal compounds are variously known under the name of so-called RM (Reactive Mesogen). The polymerizable liquid crystal compound may be polymerized in the cured layer, that is, contained in the aforementioned polymerization unit, which is polymerized to form a skeleton such as a main chain or a side chain of a liquid crystal polymer in the cured layer. It can mean the state you are doing.

The polymerizable liquid crystal compound may be a monofunctional or multifunctional polymerizable liquid crystal compound. In the above, the monofunctional polymerizable liquid crystal compound is a compound having one polymerizable functional group, and the polyfunctional polymerizable liquid crystal compound may mean a compound containing two or more polymerizable functional groups. In one example, the multifunctional polymerizable liquid crystal compound has 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, 2 to 3 polymerizable functional groups Or it may include two or three.

The curing in which birefringence is expressed by curing a polymerizable liquid crystal composition prepared by mixing the polymerizable liquid crystal compound as described above with other components such as an initiator, a stabilizer and/or a non-polymerizable liquid crystal compound, in an aligned state on an alignment film. It is known to form a layer. The retardation film having reverse dispersion characteristics may be prepared by including a polymerizable liquid crystal compound having reverse dispersion characteristics.

In the above, the polymeric stretched film is, for example, one type from the group consisting of a polyurethane-based polymer, a cellulose-based polymer, a polycarbonate-based polymer, a polyester-based polymer, a polyolefin-based polymer, a polyamide-based polymer, and a polyvinyl alcohol-based polymer. It may include more than one.

The method of obtaining the polymeric stretched film is not particularly limited. For example, it can be obtained by molding the polymer material into a film form and then stretching it. The method of forming the film in the form of a film is not particularly limited, and it is possible to form a film by known methods such as sheet forming, blow molding, extrusion molding, and cast molding. Among them, extrusion molding and cast molding are preferably used. At this time, for example, the unstretched film may be extruded using an extruder equipped with a T-die, a circular die, or the like. In the case of obtaining a molded article by extrusion molding, if a material obtained by melt-kneading various resin components, additives, and the like in advance may be used, it may be molded through melt-kneading at the time of extrusion molding. Further, after dissolving various resin components using a solvent common to various resin components, for example, a solvent such as chloroform or methylene dichloride, the unstretched film can be cast-molded by cast drying and solidifying.

The polymeric stretched film is uniaxially stretched in the mechanical flow direction (MD; Mechanical Direction, longitudinal direction or longitudinal direction), 1 in a direction perpendicular to the mechanical flow direction (TD; Transverse Direction, transverse direction, or width direction). It can be uniaxially stretched in axial stretching, mechanical flow direction and inclined direction, and is biaxially stretched by sequential biaxial stretching method of roll stretching and tenter stretching, simultaneous biaxial stretching method by tenter stretching, biaxial stretching method by tubular stretching, etc. You can also manufacture a stretched film.

Control of the retardation value of the polymeric stretched film can be generally performed by controlling stretching conditions such as the thickness of the film fabric and the stretching temperature and stretching ratio of the film. This is because the retardation value is determined by the thickness of the film itself and the orientation degree of the constituent polymer due to the stretching of the film.

The pressure-sensitive adhesive layer may perform a function of attaching the circularly polarizing plate to the display panel. The pressure-sensitive adhesive layer may include an adhesive resin. As the adhesive resin, for example, a light-transmitting adhesive resin may be used. For example, it is possible to use a pressure-sensitive adhesive resin such that the transmittance of the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive layer to a wavelength of 380 nm to 780 nm is about 80% or more, 85% or more, 90% or more, or 95% or more. The transmittance may mean a percentage of the amount of light that passes through the pressure-sensitive adhesive layer with respect to the amount of light incident on the pressure-sensitive adhesive layer. Such adhesive resin may include, for example, any one or more selected from the group consisting of acrylic resins, silicone resins, ester resins, urethane resins, amide resins, ether resins, fluorine resins and rubber resins. .

The thickness of the pressure-sensitive adhesive layer may be, for example, in the range of 15 μm to 30 μm.

The method of forming the pressure-sensitive adhesive layer on one surface of the retardation film is not particularly limited. In one example. After forming a pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition including the pressure-sensitive adhesive resin to a release film, the pressure-sensitive adhesive layer may be transferred to one surface of the retardation film and then the release film may be removed. In another example, the pressure-sensitive adhesive layer may be formed by directly applying the pressure-sensitive adhesive composition to one surface of the retardation film.

The circularly polarizing plate may have a transmittance of 35% or less, 30% or less, 25% or less, or 20% or less for a wavelength of 430 nm. Since the circularly polarizing plate satisfies such a transmittance range, it can contribute to a neutral reflective color, so even if a retardation film having a reverse dispersion characteristic having a Rin (450)/Rin (550) value equal to or higher than a certain level is used, reflection visibility can be improved. The lower limit of the transmittance of the circularly polarizing plate to a wavelength of 430 nm may be 4% or more. When the transmittance is too low, the color change of white light emitted from the OLED becomes too large, and the lower limit of the transmittance of the pressure-sensitive adhesive layer including the dye is preferably within the above range.

More specifically, the circularly polarizing plate may have a transmittance of 35% or more or 40% or more for wavelengths of 460 nm and 550 nm, respectively.

The circularly polarizing plate may include a dye. The dye functions to control the transmittance of the circularly polarizing plate. In the present specification, the dye may mean a material capable of intensively absorbing and/or modifying light in at least a part or the entire range in a visible light region, for example, in a wavelength range of 380 nm to 780 nm.

The dye may be appropriately selected within a range that allows the circularly polarizing plate to exhibit the transmittance characteristics. The dye may be, for example, a dye exhibiting absorption in the blue region. The dye may exhibit a maximum absorbance in the blue region. In the present specification, the absorption to absorbance of the dye may be determined from a transmittance spectrum measured for a layer formed by mixing the dye with a light-transmitting resin. In the present specification, the light-transmitting resin may mean a layer having a transmittance of about 80% or more, 85% or more, 90% or more, or 95% or more for a wavelength of 380 nm to 780 nm, measured for a layer formed by the resin alone. .

A dye having the above absorption characteristics may be abbreviated as a blue cut dye in the present specification. The blue region may be in a wavelength range of 370 nm to 430 nm, for example. Accordingly, the circularly polarizing plate including the dye may also exhibit a maximum absorbance within a range of 370 nm to 430 nm of a wavelength range of 380 nm to 780 nm. Since the dye absorbs the blue region, it can exhibit a yellow color. The dye may be a single dye or a mixture of two or more dyes within a range in which the circularly polarizing plate exhibits the transmittance characteristics.

The dyes include anthraquinone-based dyes, methine-based dyes, azomethine-based dyes, oxadine-based dyes, azo-based dyes, styryl-based dyes, coumarin-based dyes, porphyrin-based dyes, dibenzofuranone-based dyes, tiketophylophilol-based dyes. One or more dyes selected from the group consisting of dyes, rhodamine-based dyes, xanthene-based dyes, and pilomethene-based dyes may be used.

The dye may be included in any layer included in the circular polarizing plate within a range that allows the circular polarizing plate to exhibit the transmittance.

For example, the dye may be included in one or more of the antireflection film, retardation film, and pressure-sensitive adhesive layer. In one example, the dye may be included in the antireflection film. As described above, the antireflection film may include a base layer and a low refractive index layer on one surface of the base layer. In this case, the dye may be included in the base layer of the antireflection film. Alternatively, as described above, the antireflection film may further include a hard coating layer between the base layer and the low refractive layer. In this case, the dye may be included in the hard coating layer of the antireflection film. In one example, the dye may be included in the retardation film. As described above, when the retardation film is a liquid crystal polymerized film, the retardation film may include a substrate layer and a liquid crystal layer on one surface of the substrate layer. In this case, the dye may be included in the base layer of the retardation film. Meanwhile, when the retardation film is a polymer stretched film, the dye may be included in the polymer stretched film. In one example, the dye may be included in the pressure-sensitive adhesive layer.

In another example, the circularly polarizing plate may further include a separate layer for use for including a dye, in addition to the antireflection film, the retardation film, and the pressure-sensitive adhesive layer. Such a separate layer may also include the dye, while including the light-transmitting resin as a main component. The position of the separate layer is not particularly limited, and may be formed on one or both sides of an antireflection film, a polarizer, a retardation film, or an adhesive layer. However, since the pressure-sensitive adhesive layer is used for attaching the circularly polarizing plate to the panel, it may be preferable that the pressure-sensitive adhesive layer is not present on the adhesion surface of the pressure-sensitive adhesive layer.

The layer including the dye may have a transmittance of 90% or less, 85% or less, 80% or less, or 70% or less for a wavelength of 430 nm. Since the layer containing the dye can contribute to a neutral reflective color by satisfying this transmittance range, even if a retardation film having a reverse dispersion characteristic having a Rin (450) / Rin (550) value of more than a certain level is used, the reflection visibility can be improved. I can. More specifically, the layer including the dye may have a transmittance of 90% or more for wavelengths of 460 nm and 550 nm, respectively. The lower limit of the transmittance for the 430 nm wavelength of the layer containing the dye may be 10% or more. When the transmittance is too low, the color change of white light emitted from the OLED becomes too large, and the lower limit of the transmittance of the layer containing the dye is preferably within the above range.

The content of the dye in the layer containing the dye may be appropriately selected in consideration of the purpose of the present application. As described above, the layer containing the dye includes a light-transmitting resin as a main component, and may further include the dye. In the layer containing the dye, the content of the dye may be included in the range of, for example, 0.5 parts by weight to 10 parts by weight based on 100 parts by weight of the light-transmitting resin. When the content of the dye is within the above range, it may be appropriate to improve the reflection visibility of the circularly polarizing plate, and as the content of the dye increases within the above range, the desired reflective color may be approached. However, if the content of the dye is too high, precipitation may occur due to insufficient solubility of the dye and may affect the physical properties of each layer, so it may be preferable to adjust within the above range.

When the weight of the dye is the same in the layer containing the dye, the same transmittance characteristics can be obtained even if the thickness of the layer containing the dye is changed. Therefore, in the case of increasing the transmittance of the layer containing the dye within the above-described range, the thickness of the layer containing the dye is fixed and the weight of the dye is reduced to reduce the concentration of the dye, or a dye having the same dye concentration. There is a method of lowering the weight of the dye by lowering the thickness of the layer containing.

The present application also relates to a display device including the circularly polarizing plate. As the display device, an OLED (Organic Light Emitting Diode) device may be exemplified.

3 illustrates an OLED device of the present application by way of example. As shown in FIG. 3, the OLED device may include an OLED panel 200 and a circularly polarizing plate 100 disposed on one surface of the OLED panel. The OLED panel and the circularly polarizing plate may be attached through the pressure-sensitive adhesive layer 40 as a medium.

The OLED panel may sequentially include a substrate, a lower electrode, an organic emission layer, and an upper electrode. 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. 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. In general, a transparent metal oxide layer such as ITO or IZO having a large work function may be used as the anode, and a metal electrode having a low work function may be used as the cathode. In general, since the organic emission layer is transparent, a transparent display can be implemented when the upper and lower electrodes are made transparent. In one example, when the thickness of the metal electrode is made very thin, a transparent display can be implemented.

The OLED panel may further include an encapsulation substrate functioning to prevent the inflow of moisture and/or oxygen from the outside on the upper electrode. An auxiliary layer may be further included between the lower electrode and the organic emission layer and between the upper electrode and the organic emission layer. The auxiliary layer may include a hole transporting layer, a hole injecting layer, an electron injecting layer, and an electron transporting layer for balancing electrons and holes. However, it is not limited thereto.

The circular polarizing plate may be disposed on the side from which light is emitted from the OLED device. For example, in the case of a bottom emission structure that emits light toward the base substrate, it may be disposed on the outside of the base substrate, and in the case of a top emission structure that emits light toward the encapsulation substrate, it may be disposed outside the encapsulation substrate. have. The circularly polarizing plate can improve visibility and display performance by preventing external light from being reflected by a reflective layer made of metal such as electrodes and wirings of the OLED panel and coming out of the OLED panel.

In one example, the OLED panel may further include a substrate on which a color filter is formed. The substrate on which the color filter is formed may be disposed on the opposite side of the OLED panel on which the metal electrode is disposed. In this case, the OLED panel may have a structure including a substrate on which a color filter is formed, a transparent metal oxide electrode (anode), a light emitting layer, a metal electrode (cathode), and a base substrate in sequence. The color filter may include red, green, and blue regions, and may further include a black matrix for classifying the regions. When the color filter is present on the substrate of the OLED panel, it may exhibit a lower reflectance than when the color filter is not present. Specifically, when the red, green, and blue color filters are located in front of the emission layer of the OLED, it is because they reduce the high reflectance at the metal electrode located on the back side of the emission layer.

As the OLED panel, a panel having an average reflectance of 45% or less in a region of 410 nm to 500 nm may be used. Meanwhile, the average reflectance of the OLED panel in a region of 410 nm to 500 nm may be 20% or more. In addition, as the OLED panel, an OLED panel having an average reflectance of 50% or less in a region of 600 nm to 650 nm may be used. Meanwhile, as the OLED panel, an OLED panel having an average reflectance of 20% or more in a region of 600 nm to 650 nm may be used. Through the application of such an OLED panel, it may be more advantageous to improve reflection visibility while using a retardation film having a reverse dispersion characteristic having a Rin(450)/Rin(550) value of at least a certain level.

As described above, an OLED device in which the circularly polarizing plate of the present application is applied to an OLED panel can exhibit excellent reflection visibility. In one example, the reflectance of 550 nm of the OLED panel to which the circularly polarizing plate is attached may be 1.5% or less. The reflectance may be specifically 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, or 1.0% or less. The lower the reflectance of the OLED panel to which the circularly polarizing plate is attached, the better the reflective luminance is, and the lower limit is not particularly limited, but may be, for example, 0.1% or more.

In one example, the reflective color of the OLED panel to which the circularly polarizing plate is attached may satisfy Equation 3 or Equation 4 below based on ^{L *} a ^* b ^{* color coordinates.} The circularly polarizing plate may satisfy either Equation 3 or 4, or both.

[Equation 3]

< 8

<8

[Equation 4]

0 <a ^* <6 and -6 <b ^* <0

When the reflectance and the reflective color of the OLED panel with the circularly polarizing plate satisfy the above conditions, it can be said that the reflection visibility is excellent. In addition, among the a ^* and b ^* values, ^{the range of a *} value may be more important, because in general, the reflective color of red light more deteriorates the viewer's sense of sight than blue light. In addition, when the reflectance of the OLED panel with respect to the 550 nm wavelength is in the above range, ^{even if the absolute values of a *} and b ^* increase, it feels darker, so it may be more advantageous in improving reflection visibility.

The present application may provide a circularly polarizing plate capable of improving reflection visibility and an OLED device including the circularly polarizing plate by neutralizing the reflective color of the OLED panel by using a retardation film having reverse dispersion characteristics.

1 shows an exemplary circularly polarizing plate of the present application.
2 shows an exemplary reflectance spectrum of an antireflection film.
3 illustrates an OLED device of the present application by way of example.
4 is a reflectance spectrum of an antireflection film.
5 is a transmittance spectrum of a blue cut die and a polarizer.
6 is a reflectance spectrum of an OLED panel.

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.

Preparation Example 1. Preparation of retardation film

Polyurethane resin A was prepared by bulk polymerization. More specifically, after melting 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene at 170°C, the temperature was lowered to 140°C. Then, 1,6-hexamethylene diisocyanate and 4,4-methylenedicyclohexyl diisocyanate were mixed in a molar ratio of 2:1, and 9,9-bis[4-(2-hydroxyethoxy) in a molten state Into phenyl]fluorene and stirred. At this time, the equivalent ratio of the fluorene-based monomer and the isocyanate-based monomer was 1.03 (that is, the ratio of the isocyanate group and the hydroxy group was 1.03:1). Finally, the agitated product was cured at 150° C. for 18 hours to prepare a polyurethane-based resin A. On the other hand, the glass transition temperature of the polyurethane-based resin A measured using DSC was 125°C.

The prepared polyurethane resin A is pulverized with a grinder to prepare a powdery raw material, melted in a twin screw extruder, passed through a coat hanger type Tdie, and passed through a chrome plated casting roll to a film having a certain thickness. The fabric was prepared. This film fabric was stretched at a rate of twice at a constant temperature using an experimental film stretching equipment to prepare a retardation film. The retardation film of Preparation Example 1 had a Rin (450)/Rin (550) value of 0.92. At this time, the Rin (550) value was adjusted by adjusting the thickness and stretching temperature conditions of the raw film as shown in Table 1 below.

Preparation Example 2. Preparation of retardation film

Polyurethane resin B was prepared by bulk polymerization. More specifically, after melting 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene at 170°C, the temperature was lowered to 140°C. Then, 1,6-hexamethylene diisocyanate was added to 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene in a molten state, and stirred. At this time, the equivalent ratio of the fluorene-based monomer and the isocyanate-based monomer was 1.03 (that is, the ratio of the isocyanate group and the hydroxy group was 1.03:1). Finally, the agitated product was cured at 150° C. for 18 hours to prepare a polyurethane-based resin B. On the other hand, the glass transition temperature of the polyurethane-based resin B measured using DSC was 108°C. The retardation film of Preparation Example 2 had a Rin(450)/Rin(550) value of 0.87. At this time, the Rin (550) value was adjusted by adjusting the thickness and stretching temperature conditions of the raw film as shown in Table 1 below.

Suzy
Rin(450)/Rin(550) Tg(℃) Fabric thickness (㎛) Stretching temperature (℃) Film thickness (㎛) Rin(nm) Suzy A
0.92 123 93 113 65 144 101 116 71 141 112 118 79 139 128 121 90 137.5 147 123 104 135 Suzy B
0.87 108 136 98 96 144 148 101 105 141 165 103 117 139 188 106 133 137.5 217 108 153 135

Examples 1 to 30, Comparative Examples 1 to 10 and Reference Examples 1 to 40

Circular polarizer

A circularly polarizing plate including an antireflection film, a polarizer, a retardation film, and an adhesive layer in sequence was prepared.

The antireflection film is coated with a hard coating layer having a thickness of about 3 μm and a refractive index of 1.5 for a wavelength of 550 nm on a triacetylcellulose (TAC) base film, and then coating a low refractive index layer on the hard coating layer. Was prepared. The low refractive layer is a low refractive material and includes hollow silica nanoparticles having a refractive index of 1.32 for a wavelength of 550 nm. The lowest reflected wavelength of the antireflection film controls the thickness of the low refractive layer, so that the lowest reflected wavelength of the antireflection film moves to a longer wavelength as the thickness of the low refractive layer increases, and moves to a shorter wavelength as the thickness of the low refractive layer decreases. Examples, Comparative Examples, and Reference Examples include anti-reflection films in which the lowest reflection wavelength is adjusted as shown in Tables 5 to 8, respectively. The reflection color and reflectance of the antireflection film may vary depending on the lowest reflection wavelength, which is specifically described in Evaluation Example 1 below.

The retardation film is a stretched film of a polyurethane-based resin, and in Examples, Comparative Examples, and Reference Examples, the Rin (450) / Rin (550) values and the Rin (550) values are respectively used as shown in Tables 5 to 8 below. Includes. As for the slow axis of the retardation film, the angle made with respect to the MD axis of the retardation film is 45 degrees, and the angle made with respect to the light absorption axis of the polarizer is 45 degrees.

As the polarizer, a PVA-based polarizer having a transmittance of 44.5% for a wavelength of 550 nm was used. The transmittance spectrum of the polarizer was specifically described in Evaluation Example 2 below.

A commercially available acrylic adhesive for polarizing plate is used as an adhesive layer, and a product coated with an adhesive between release films is used to laminate the surface of the retardation film. The thickness of the pressure-sensitive adhesive is 20 μm. The pressure-sensitive adhesive layer contains a blue cut die (Eutec Chemical Co., Ltd. Eusorb UV-1990) in an amount of 4 pt based on the solid content of the pressure-sensitive adhesive. The transmittance spectrum of the pressure-sensitive adhesive including the blue cut die was specifically described in Evaluation Example 2 below.

Evaluation Example 1. Evaluation of reflection color and reflectance of antireflection film

Table 2 below shows the lowest reflection wavelength and thickness of the antireflection film, reflection color (L ^* a ^* b ^* color coordinate) and reflectance evaluation results.

The reflectance of the antireflection film was measured by measuring the mirror reflectance of the surface layer of the antireflection coating layer using the Minolta CM-2600d equipment after attaching Black Tape that absorbs light to the back of the antireflection coating layer of the substrate. Specifically, the reflectance is a result of subtracting a Specular Component Excluded (SCE) value from a Specular Component Included (SCI) value among the measured values of the equipment. ^{Simultaneously with the above measurement, CIE 1976 L *} a ^* b ^* can be obtained under the D65 light source condition in the measuring equipment. Since most of the SCE values are reflected from the black tape attached to the back side, not the anti-reflection film, the SCE value was subtracted to determine the reflective characteristics of the anti-reflective film.

Figure 4 shows the reflectance spectrum of the anti-reflective film having the lowest reflection wavelength of 420 nm, 500 nm and 550 nm, respectively, and Table 2 shows the L ^* a ^* b ^* color coordinate of the anti-reflection film, luminous reflectance (Y), 550 nm and 430 nm. Indicates the reflectivity for.

Anti-reflection film Minimum reflected wavelength (nm) thickness
(nm) Reflective color
(D65, CIE 1976 L ^* a ^* b ^* ) reflectivity L ^* a ^* b ^* Y 550nm 430nm One 420 80 8.96 2.49 5.40 1.00% 0.98% 0.6% 2 440 84 8.25 2.84 4.57 0.91% 0.89% 0.6% 3 460 88 7.57 3.15 3.40 0.84% 0,81% 0.6% 4 480 91.5 6.98 3.32 1.91 0.77% 0.74% 0.7% 5 500 95.5 6.50 3.42 0.08 0.72% 0.67% 0.8% 6 520 99.5 6.18 3.48 -2.11 0.68% 0.63% 1.0% 7 540 103.2 6.05 3.46 -4.66 0.67% 0.60% 1.2% 8 550 105 5.72 3.57 -5.46 0.63% 0.56% 1.2%

Evaluation Example 2. Evaluation of transmission color and transmittance of pressure-sensitive adhesive and polarizing plate

Table 3 below shows the results of evaluating the transmittance and transmittance of the pressure-sensitive adhesive including the blue cut die and the polarizer before and after adhesion of the pressure-sensitive adhesive. As the pressure-sensitive adhesive including the blue-cut die, a pressure-sensitive adhesive having a thickness of about 20 μm was applied to which 4 pt of a blue-cut die (UV1990, manufactured by Eutec Chemical Co., Ltd.) was added based on the solid content of the optical pressure-sensitive adhesive.

The transmittance of the pressure-sensitive adhesive including the blue cut die was measured using Shimadzu UV-3600. Specifically, after attaching a pressure-sensitive adhesive including a blue cut die to a glass substrate, a transparent PET film was measured using a sample attached to the exposed pressure-sensitive adhesive surface again. When setting the baseline of the equipment before measuring the sample, the sample was loaded with a sample in which a transparent adhesive was introduced instead of the adhesive that has the same structure as the measurement sample and includes a blue cut die. As a result, it was measured under the condition that reflectance was not included in the transmittance of the measured sample, and thus the transmittance of the wavelength band without absorption of the die was 100%. The transmittance color of the adhesive was calculated using the transmittance data for each wavelength obtained using the Shimadzu UV-3600 equipment.

The transmittance of the polarizer was measured using a Jasco's V-7100 Spectrophotometer, and the transmittance was calculated using the previously obtained data.

5 shows the transmittance spectra of Samples 1 to 3 below.

Transmissive color
(D65, CIE 1976 L ^* a ^* b ^* ) Transmittance L ^* a ^* b ^* Y 550nm 430nm Sample 1 99.63 -7.43 15.31 99.0% 99.6% 44.4% Sample 2 72.35 -1.45 4.82 44.2% 44.5% 38.0% Sample 3 72.10 -6.11 15.02 43.8% 44.3% 16.9% Sample 1: adhesive with blue cut die
Sample 2: Polarizer without the adhesive of Sample 1 attached
Sample 3: Polarizer with adhesive of Sample 1

Evaluation Example 3. Evaluation of reflection color and reflectance of OLED panel

As an OLED panel, we prepared an OLED TV of the manufacturer LGD's model name OLED55B7K. For the OLED panel, the reflectance was measured using the Minolta's CM-2600d equipment. After removing the circularly polarizing plate from the OLED TV, the reflectance of the surface of the OLED panel was measured. 6 shows the reflectance spectrum of the OLED panel, and Table 4 shows the reflection color (L ^* a ^* b ^* color coordinate) and reflectance evaluation results of the OLED panel.

Reflective color
(D65, CIE 1976 L ^* a ^* b ^* ) reflectivity L ^* a ^* b ^* Y 550nm 430nm OLED panel 72.65 0.20 4.12 44.6% 44.2% 40.0%

Evaluation Example 4. Evaluation of OLED panel reflection color according to the structure of the circularly polarizing plate

For the OLED panel to which the circularly polarizing plate was attached, the reflective color was evaluated according to the structure of the circularly polarizing plate, and the results are shown in Tables 5 to 8 below. Using Minolta's CM-2600d equipment, a circular polarizing plate is attached to the OLED panel and the reflectance and reflection color of the CIE 1964/10° standard are measured under the condition of the D65 light source. At this time, the OLED panel is in the off state. ^{Specifically, L *} a ^* b ^* color coordinates were measured for the OLED panel to which the circularly polarizing plate was attached. In the D65 light source environment, if L ^* a ^* b ^* color coordinate criteria △a ^* b ^* <8 or 0<a ^* <6 and -6<b ^* <0 are satisfied, reflection visibility can be evaluated as excellent. .

로 계산되는 값을 의미한다. 평가 결과 실시예는 OLED 패널의 반사색이 △a^*b^* < 8를 만족하거나 또는 0 < a^* < 6 및 -6 < b^* < 0을 만족함으로써 우수한 반사색을 나타내는 것을 알 수 있다. AR _min means the lowest reflected wavelength of the antireflection film, Rin(450)/Rin(550) means the ratio of the in-plane retardation value to the 450 nm wavelength to the in-plane retardation value to the 550 nm wavelength of the retardation film. , Rin means the in-plane retardation value for _{the 550 nm wavelength of the retardation film, and 4Rin-AR min} means the value obtained by subtracting the lowest reflected wavelength of the antireflection film from the four times the in-plane retardation value for the 550 nm wavelength of the retardation film. And Y means luminous reflectance (%), and △a ^* b ^* is

It means the value calculated as. As a result of the evaluation, it can be seen that the reflective color of the OLED panel ^{satisfies Δa *} b ^* <8 or 0 <a ^* <6 and -6 <b ^* <0, thereby exhibiting excellent reflective colors.

[Table 5]

[Table 6]

[Table 7]

[Table 8]

10: anti-reflection film, 20: polarizer, 30: retardation film 40: pressure-sensitive adhesive layer
100: circularly polarizing plate 200: OLED panel

Claims (14)

A circular polarizing plate sequentially including an antireflection film, a polarizer, a retardation film having a Rin(450)/Rin(550) value of 0.9 or more and less than 1, and an adhesive layer, wherein the lowest reflection wavelength of the antireflection film is 520 nm or less, A circularly polarizing plate having a transmittance of 35% or less for a wavelength of 430 nm of the circularly polarizing plate (Rin(λ) is an in-plane retardation value with respect to a wavelength of λ nm). The circularly polarizing plate according to claim 1, wherein the lowest reflection wavelength of the antireflection film is 390 nm or more. The circularly polarizing plate of claim 1, wherein the antireflection film has a minimum reflectance of 1% or less, and has one wavelength band having a reflectance of 1% or less within a wavelength range of 380 nm to 780 nm. The circularly polarizing plate of claim 1, wherein the reflection color of the antireflection film satisfies a color coordinate criterion ^{of L *} a ^* b ^{* b * >0.} The circularly polarizing plate according to claim 1, wherein the transmittance of the polarizer to a wavelength of 550 nm is in the range of 40% to 50%. The polarizing plate of claim 1, wherein the retardation film has an in-plane retardation value in the range of 130 nm to 150 nm with respect to a wavelength of 550 nm calculated by Equation 1 below:
[Equation 1]
Rin = d × (nx-ny)
In Equation 1, Rin means the in-plane retardation, d is the thickness of the retardation film, nx is the refractive index in the in-plane slow axis direction of the retardation film, and ny is the refractive index in the in-plane fast axis direction of the retardation film. The polarizing plate of claim 1, wherein the retardation film has a retardation value in a thickness direction of 65 nm to 140 nm for a wavelength of 550 nm calculated by Equation 2 below:
[Equation 2]
Rth = d × [(nx + ny)/2-nz]
In Equation 2, Rth is the retardation in the thickness direction, d is the thickness of the retardation film, nx is the refractive index in the in-plane slow axis direction of the retardation film, ny is the refractive index in the in-plane fast axis direction of the retardation film, and nz is the retardation. It is the refractive index in the thickness direction of a film. The circularly polarizing plate according to claim 1, wherein an angle formed by the slow axis of the retardation film with the absorption axis of the polarizer is in the range of 43 degrees to 47 degrees. The method of claim 1, wherein the retardation film is at least one selected from the group consisting of a polyurethane-based polymer, a cellulose-based polymer, a polycarbonate-based polymer, a polyester-based polymer, a polyolefin-based polymer, a polyamide-based polymer, and a polyvinyl alcohol-based polymer. Circular polarizing plate comprising a. The circularly polarizing plate of claim 1, wherein the circularly polarizing plate has a transmittance of 4% or more for a wavelength of 430 nm, and a transmittance of 40% or more for a wavelength of 460 nm and 550 nm, respectively. The circularly polarizing plate of claim 1, wherein the circularly polarizing plate further comprises a dye exhibiting a maximum absorbance in the range of 370 nm to 430 nm. An OLED device comprising an OLED (Organic light emitting diode) panel and the circularly polarizing plate of claim 1 disposed on one surface of the OLED panel. The OLED device of claim 12, wherein the OLED panel has an average reflectance of 45% or less in a region of 410 nm to 500 nm, and an average reflectance of 50% or less in a region of 600 nm to 650 nm. The OLED device according to claim 12, wherein the reflective color of the OLED panel to which the circularly polarizing plate is attached ^{satisfies the L *} a ^* b ^* color coordinate standard, Equation 3 or 4:
[Equation 3]

[Equation 4]
0 <a ^* <6 and -6 <b ^* <0.

Images