KR20210077214A - Polarizing plate - Google Patents

Abstract

This application is applied to an OLED panel, particularly a WRGB type OLED panel, and provided is a polarizing plate, so that 10000k white can be realized while minimizing driving energy for blue, red and/or green devices, and an OLED device can exhibit high luminance and excellent color reproducibility. The polarizing plate includes: a polarizer; a retardation layer formed under the polarizer; and a pressure-sensitive adhesive layer formed under the retardation layer.

Description

Polarizing plate

This application relates to a polarizer and an OLED device.

OLED (Organic Light Emitting Diode) panels are being applied to various uses such as large TVs, mobile devices, and lighting.

An OLED panel, particularly an OLED panel applied to a display, is divided into a so-called RGB method and a WRGB method (also called an RGBW method) according to the structure of sub-pixels. WRGB type OLED panel is also called white OLED panel. The RGB method is a method in which red, green, and blue elements are repeatedly arranged in order, and in the WRGB method, white elements are added to red, green, and blue elements. added method.

A polarizing plate is usually attached to an OLED panel on the viewer side to prevent reflection due to an internal structure and to secure a sense of black visibility.

The brightness of the OLED panel to which the polarizer is attached can be represented by the performance of displaying so-called 10000k white, that is, white having a color temperature of 10000k. White with a color temperature of 10000k is a bluish white that is somewhat blue.

In order to realize the 10000k white color, a combination of blue, red and/or green elements, which are sub-pixels in the pixels of the OLED panel, is used, and in the WRGB method, white elements are also used. do.

In the WRGB type OLED panel, since a color filter is used for the blue, red, and/or green elements, the efficiency is lowered, and this low efficiency causes a decrease in luminance and/or excessive driving of the device. It causes problems such as energy consumption.

This application relates to a polarizing plate. The present application is applied to an OLED panel, particularly a WRGB type OLED panel, so that 10000k white can be realized while minimizing driving energy for blue, red and/or green devices, and OLED device One object of the present invention is to provide a polarizing plate capable of exhibiting high luminance and excellent color reproducibility.

An exemplary polarizing plate includes a polarizer, a retardation layer, and an adhesive layer. The retardation layer may be stacked under the polarizer, and the pressure-sensitive adhesive layer may be stacked under the retardation layer. 1 is a cross-sectional view of a polarizing plate sequentially including the polarizer 100 , the retardation layer 200 , and the pressure-sensitive adhesive layer 300 .

The term "lower" refers to a direction from the polarizer toward the retardation layer, and the term "upper" refers to a direction opposite to the lower portion. The upward direction may be a direction in which light from the OLED panel travels when the polarizer of the present application is applied to the OLED panel. That is, when the polarizer of the present application is applied to an OLED panel, light generated from the OLED panel may transmit the pressure-sensitive adhesive layer, the retardation layer, and the polarizer in the above order.

In the present application, the transmission spectrum or absorption spectrum of the polarizing plate is controlled to a predetermined level. Such a polarizing plate enables an OLED device (especially a device including a WRGB-type OLED panel) to realize 10000k white while minimizing driving energy for blue, red and/or green elements. and high luminance and excellent color reproducibility.

Currently, a combination of a white element, a red element, and a blue element is applied to realize 10000k white in the WRGB type OLED panel. In contrast, the OLED panel to which the polarizing plate of the present application is applied realizes the 10000k white color only by a combination of a white element and a blue element, or a white element, a red element, and a blue color element. Even when a combination of devices is applied, the 10000k white can be realized while minimizing energy consumed for driving the red and/or blue devices. Accordingly, the OLED panel to which the polarizing plate is applied can realize 10000k white color even with low power consumption, and also exhibit high luminance and excellent color reproducibility.

The polarizing plate of the present application may exhibit, for example, a spectrum satisfying the following formula A.

[Formula A]

100 ≤ 100×I ₅₅₀ /I ₄₅₀ < 107

In Equation A, I ₅₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 550 nm, and I ₄₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 450 nm.

100×I ₅₅₀ /I ₄₅₀ in Formula A may be 101 or more, 102 or more, or 103 or more in another example, or about 106 or less, 105 or less, or 104.5 or less in another example.

The polarizing plate of the present application may exhibit, for example, a spectrum satisfying the following formula B.

[Formula B]

90 ≤ 100×I ₆₀₀ /I ₅₅₀ < 115

In Equation B, I ₅₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 550 nm, and I ₆₀₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 600 nm.

100×I ₆₀₀ /I ₅₅₀ of Formula B is 91 or more, 92 or more, 93 or more, 94 or more, 95 or more, 96 or more, 97 or more, 98 or more, 99 or more, 100 or more, 101 or more, 102 or more, 103 or more or 104 or more, and in other examples 114 or less, 113 or less, 112 or less, 111 or less, 110 or less, 109 or less, 108 or less, 107 or less, 106 or less, 105 or less, 104 or less, 103 or less, 102 or less, 101 or less, 100 or less, or 99 or less.

The polarizing plate of the present application may exhibit, for example, a spectrum satisfying the following Equation C.

[Formula C]

95 ≤ 100×I ₆₅₀ /I ₆₀₀ < 115

In Equation C, I ₆₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 650 nm, and I ₆₀₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 600 nm.

100×I ₆₅₀ /I ₆₀₀ of Formula C may be 96 or more, 97 or more, 98 or more, 99 or more, 100 or more, 101 or more, 102 or more, or 103 or more in another example, and 114 or less, 113 or less, 112 or more in another example It may be 111 or less, 110 or less, 109 or less, 108 or less, 107 or less, 106 or less, 105 or less, 104 or less, 103 or less, 102 or less, 101 or less, or 100 or less.

It is possible to provide a polarizing plate capable of satisfying the object of the present application in relation to the transmittance as described above. The method for adjusting the transmittance spectrum of the polarizing plate to the above range is not particularly limited, and for example, a method of including a dye capable of absorbing light of a predetermined range of wavelengths at an appropriate position of the polarizing plate in an appropriate ratio, as will be described later. this can be used

The specific range of each transmittance in Formulas A to C is not particularly limited. _{For example, the transmittance (I 450} ) of the polarizing plate for light having a wavelength of 450 nm in the above may be in the range of about 30% to 50%. The transmittance (I ₄₅₀ ) is 31% or more, 32% or more, 33% or more, 34% or more, 35% or more, 36% or more, 37% or more, 38% or more, or 39% or more, or 49% or less in another example. , 48% or less, 47% or less, 46% or less, 45% or less, 44% or less, 43% or less, 42% or less, or 41% or less.

_{The transmittance (I 450} , I ₅₅₀ , I ₆₀₀ , I ₆₅₀ ) of the polarizing plate with respect to the light of each wavelength is the transmittance when the light of each corresponding wavelength is incident and transmitted to the pressure-sensitive adhesive layer side of the polarizing plate, and a known measuring device, e.g. For example, it can be measured using Shimadzu's UV-36007 equipment.

The types of specific components applied to the polarizing plate of the present application are not particularly limited. In the present application, commonly applied components may be applied.

The polarizer applied to the polarizing plate of the present application is a film, sheet, or device having a polarization function. A polarizer is a functional element capable of extracting light vibrating in one direction from incident light vibrating in multiple directions.

As the polarizer, an absorption type linear polarizer can 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.

For example, a polarizer having a single transmittance (Ts) of 20% or more or 60% or less for light having a wavelength of 390 nm may be used as the polarizer. In another example, the transmittance of the polarizer with respect to the 390 nm wavelength light is 59% or less, 58% or less, 57% or less, 56% or less, 55% or less, 54% or less, 53% or less, 52% or less, 51% or less. or less, 50% or less, 49% or less, 48% or less, 47% or less, 46% or less, 45% or less, 44% or less, 43% or less, 42% or less, 41% or less, or 40% or less, or 21% or more , 22% or more, 23% or more, 24% or more, or 25% or more. The single transmittance of the polarizer can be measured using, for example, a spectrometer (V7100, manufactured by Jasco). For example, set air as the base line while the polarizer sample (without the upper and lower protective films are not included) mounted on the device, and measure the transmittance of the polarizer sample while aligning the axis of the polarizer sample vertically and horizontally with the axis of the reference polarizer. After the measurement, the single transmittance can be calculated.

Typically, a PVA (poly(vinyl alcohol))-based linear absorption type polarizer exhibits the above-mentioned single transmittance, and in the present application, such a PVA-based linear absorption type polarizer may be applied. is not limited to the above.

The PVA polarizer generally includes a PVA film or sheet and an anisotropic absorptive material such as a dichroic dye or iodine adsorbed and oriented to the PVA film or sheet, and in the present application, such a conventional PVA polarizer may also be applied. That is, the polarizer applied in the present application may include a PVA film or sheet and an anisotropic absorbent material adsorbed on the PVA film or sheet. In the above, the anisotropic absorbent material may be iodine, and this polarizer may be referred to as an iodine-based PVA polarizer in the present application.

In the polarizing plate, a retardation layer is present under the polarizer. The retardation layer may be, for example, a layer having a refractive index relationship according to any one of Equations 1 to 3 below.

[Formula 1]

nx > ny = nz

[Formula 2]

nx > ny > nz

[Equation 3]

nx > ny and nz > ny

In Equations 1 to 3, nx, ny, and nz are the refractive index in the x-axis direction (slow axis direction), the refractive index in the y-axis direction (fast axis direction), and the refractive index in the z-axis direction (thickness direction), respectively. Unless otherwise specified, the same may be applied herein. In the above, the x-axis direction, for example, as shown in FIG. 2, means a slow axis direction on the plane of the retardation layer 100 in the form of a film or sheet, and the y-axis direction is a plane direction perpendicular to the x-axis. (fast axis direction), and the z-axis direction may mean a direction of a normal line of a plane formed by the x-axis and the y-axis, for example, a thickness direction.

Unless otherwise specified, the term refractive index herein refers to the refractive index for light having a wavelength of about 550 nm.

The retardation layer may have, for example, an in-plane retardation within a range that may have a quarter-wave retardation characteristic. As used herein, the term n-wavelength phase retardation characteristic refers to a characteristic capable of retarding incident light by n times the wavelength of the incident light within at least part of a wavelength range. The quarter-wave phase delay characteristic may be a characteristic of converting incident linearly polarized light into elliptically polarized light or circularly polarized light, and converts reversely incident elliptically polarized light or circularly polarized light into linearly polarized light. In one example, the retardation layer may have an in-plane retardation of light with a wavelength of 550 nm in a range of 90 nm to 300 nm. The in-plane retardation may be 100 nm or more, 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, or 130 nm or more in another example. In addition, the in-plane retardation is 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, or 145 nm or less.

In the present specification, the term in-plane retardation is a value determined according to Equation 4 below, and the thickness direction retardation is a value determined according to Equation 5 below.

[Equation 4]

Rin = d Х (nx - ny)

[Equation 5]

Rth = d Х (nz - ny)

In Equations 4 and 5, Rin is the in-plane retardation, Rth is the thickness direction retardation, nx, ny, and nz are as defined in Equations 1 to 3, and d is the thickness of the retardation layer.

The range of the retardation in the thickness direction obtained according to Equation 5 for the retardation layer is not particularly limited, and may be, for example, in the range of about -200 nm to 200 nm. In another example, the thickness direction retardation is -190 nm or more, -180 nm or more, -170 nm or more, -160 nm or more, -150 nm or more, -140 nm or more, -130 nm or more, -120 nm or more, -110 nm or more, -100 nm or more, -90 nm or more, -80 nm or more, -70 nm or more, -60 nm or more, -50 nm or more, -40 nm or more, -30 nm or more, -20 nm or more, or -10 nm or larger. In addition, the thickness direction retardation in another example is 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less.

In one example, the retardation layer may be a layer satisfying Equation 6 below.

[Equation 6]

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

In Equation 6, R(450) is the in-plane retardation of the retardation layer with respect to light of a wavelength of 450 nm, R(550) is the in-plane retardation of the retardation layer with respect to light of a wavelength of 550 nm, R(650) is 650 It is the in-plane retardation of the retardation layer with respect to the light of the wavelength of nm.

Each of the in-plane retardation is according to Equation 4, except that the in-plane retardation for the light of the 450 nm wavelength is nx and ny in Equation 4, the refractive index for the light of the 450 nm wavelength is applied, and the in-plane retardation for the light of the 550 nm wavelength As nx and ny in Equation 4, the refractive index for light with a wavelength of 550 nm is applied, and the in-plane retardation for light with a wavelength of 650 nm is nx and ny in Equation 4, and the refractive index for light with a wavelength of 650 nm is applied.

The retardation layer satisfying Equation 6 is a retardation layer having so-called reverse wavelength dispersion. Such a retardation layer may exhibit a designed phase delay characteristic in a wide wavelength range.

By adjusting R(450)/R(550) and/or R(650)/R(550) in the retardation layer satisfying Equation 6, a polarizing plate having a better effect may be provided. In one example, R(450)/R(550) in Equation 6 may be in the range of 0.6 to 0.99. R (450) / R (550) is, in another example, 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.69 or more, 0.70 or more, 0.71 or more, 0.72 or more, 0.73 or more, 0.74 or higher, 0.75 or higher, 0.76 or higher, 0.77 or higher, 0.78 or higher, 0.79 or higher, 0.80 or higher, 0.81 or higher, 0.82 or higher, 0.83 or higher, 0.84 or higher, 0.85 or higher, 0.86 or higher, 0.87 or higher, 0.88 or higher, 0.89 or higher, or 0.90 or higher can In another example, R(450)/R(550) is 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less , 0.86 or less or 0.85 or less. R(650)/R(550) in Equation 6 may be in the range of 1.00 to 1.19. The R(650)/R(550) may be 1.18 or less, 1.17 or less, 1.16 or less, 1.15 or less, 1.14 or less, 1.13 or less, 1.12 or less, 1.11 or less, 1.1 or less, or 1.08 or less. R(650)/R(550) of Equation 6 may be 1.01 or more, 1.02 or more, 1.03 or more, 1.04 or more, 1.05 or more, 1.06 or more, 1.07 or more, 1.08 or more, or 1.09 or more in another example.

The method of adjusting R (450) / R (550) and / or R (650) / R (550) of the retardation layer in the above range is not particularly limited, but in the present application, the ultraviolet absorber or the light stabilizer is not included. Even in this case, in order to secure the desired UV blocking ability, the reverse wavelength characteristics as described above can be implemented using two different polymerizable liquid crystal compounds.

The retardation layer may be laminated on one side of the polarizer such that its slow axis and the absorption axis of the polarizer form an angle within the range of about 30 degrees to 60 degrees. The angle may be 35 degrees or more or 40 degrees or more in another example, and may be 55 degrees or less or 50 degrees or less.

As the retardation layer, a known material may be used without particular limitation as long as it has the above characteristics.

For example, 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.

As the stretched polymer layer in the above, for example, polyolefin such as polyethylene or polypropylene, cycloolefin polymer (COP) such as polynorbornene, polyvinyl chloride, polyacrylonitrile, polysulfone, acrylic resin , Polycarbonate, polyester such as polyethylene terephthalate, polyacrylate, polyvinyl alcohol, or cellulose ester-based polymer such as TAC (Triacetyl cellulose) or a copolymer of two or more monomers among the monomers forming the polymer, etc. A polymer layer may be used.

In addition, a known material that can exhibit the above properties can be applied to the liquid crystal polymer layer or the cured layer of the polymerizable liquid crystal compound.

In one example, a liquid crystal polymer layer or a cured layer of a polymerizable liquid crystal composition may be applied as the retardation layer. For example, a cured layer of a polymerizable liquid crystal composition including a polymerizable liquid crystal compound having reverse wavelength characteristics may be applied. For example, the retardation layer may include a polymerization unit of a normal dispersion polymerizable liquid crystal compound and a polymerization unit of a reverse dispersion polymerizable liquid crystal compound. In the above, the polymerization unit means a unit formed by polymerization or curing of each of the polymerizable liquid crystal compounds.

For example, in the present application, a retardation layer may be prepared by mixing two or more polymerizable liquid crystal compounds to satisfy the properties of Equation 6, for example, R(450)/R(550) is a low value. The properties of Equation 6 may be satisfied by combining the polymerizable liquid crystal compound represented by the polymerizable liquid crystal compound and the polymerizable liquid crystal compound having a high R(450)/R(550) value.

The term "polymerizable liquid crystal compound" may refer to a compound including a moiety capable of exhibiting liquid crystallinity, for example, a mesogen skeleton, and 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 included in the polymerized form in the cured layer, that is, as the above-described polymerized unit, which forms a backbone such as a main chain or side chain of the liquid crystal polymer in the cured layer by polymerization of the liquid crystal compound. It can mean a state of being.

The polymerizable liquid crystal compound may be a monofunctional or polyfunctional polymerizable liquid crystal compound. In the above, the monofunctional polymerizable liquid crystal compound may be a compound having one polymerizable functional group, and the polyfunctional polymerizable liquid crystal compound may mean a compound including two or more polymerizable functional groups. In one example, the polyfunctional 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 two or three.

The cured layer in which birefringence is expressed by curing the polymerizable liquid crystal compound prepared by mixing the polymerizable liquid crystal compound with other components such as, for example, an initiator, a stabilizer and/or a non-polymerizable liquid crystal compound, aligned on an alignment film Formation is known.

In the present application, among the reverse wavelength polymerizable liquid crystal compounds, R(450)/R(550) of Equation 6 may be applied to a liquid crystal compound in the range of 0.6 to 0.99. R (450) / R (550) of the inverse dispersion polymerizable liquid crystal compound is, in another example, 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.69 or more, 0.70 or more, 0.71 or more or more, 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, 0.78 or more, 0.79 or more, 0.80 or more, 0.81 or more, 0.82 or more, 0.83 or more, 0.84 or more, 0.85 or more, 0.86 or more, 0.87 or more, 0.88 or greater, 0.89 or greater, or 0.90 or greater. In another example, R(450)/R(550) is 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less , 0.86 or less or 0.85 or less. In addition, in the reverse wavelength polymerizable liquid crystal compound, R(650)/R(550) of Equation 6 may be in the range of 1.00 to 1.19. The R(650)/R(550) may be about 1.18 or less, 1.17 or less, 1.16 or less, 1.15 or less, 1.14 or less, 1.13 or less, 1.12 or less, 1.11 or less, 1.1 or less, or 0.08 or less. The R(650)/R(550) may be about 1.01 or more, 1.02 or more, 1.03 or more, 1.04 or more, 1.05 or more, 1.06 or more, 1.07 or more, 1.08 or more, or 1.09 or more in another example. In the case of a polymerizable liquid crystal compound having a value within the range of R (450)/R (550) as described above, when blended with a normal dispersion polymerizable liquid crystal compound, a retardation layer having desired properties can be effectively formed. The R (450) / R (550) is 0.6 or more, 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.68 or more, 0.69 or more, 0.70 or more, 0.71 or more, 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, or 0.78 or more.

In the industry, various reverse wavelength polymerizable liquid crystal compounds having the above characteristics are known, and in the present application, the retardation layer may be formed using such a known polymerizable liquid crystal compound.

The polymerized unit of the reverse wavelength polymerizable liquid crystal compound may be included in the cured layer (liquid crystal layer) in an amount of 40 wt% or more based on the weight of the total polymerizable liquid crystal compound in the cured layer (liquid crystal layer). In another example, the ratio is about 45 wt% or more, 50 wt% or more, 55 wt% or more, 60 wt% or more, 65 wt% or more, 70 wt% or more, 75 wt% or more, 80 wt% or more, 85 wt% or more. or more, 80% by weight or more, or 95% by weight or more. The proportion may be less than or equal to 100% by weight or less than 100% by weight.

The polymerizable liquid crystal composition and/or the cured layer (liquid crystal layer) has R (450) / R (550) of 1.04 to 1.25, 1.04 to 1.15, or 1.06 to 1.15 in Equation 1 in addition to the reverse dispersion polymerizable liquid crystal compound. It may further include a polymerizable liquid crystal compound within the range (hereinafter, a normal dispersion polymerizable liquid crystal compound). The overall optical properties may be adjusted by adding a polymerizable liquid crystal compound having an R (450)/R (550) value within the above range in the polymerizable liquid crystal composition and/or the cured layer. In the normal dispersion liquid crystal compound, R(650)/R(550) in Equation 6 may be in the range of about 0.8 to 0.99, about 0.85 to 0.99, about 0.9 to 0.99, or about 0.91 to 0.99.

Various well-dispersion polymerizable liquid crystal compounds having the above properties are known in the industry, and in the present application, the retardation layer may be formed using such a known polymerizable liquid crystal compound.

The ratio of the positively dispersed polymerizable liquid crystal compound in the cured layer (liquid crystal layer) is as long as optical properties such as the R (450)/R (550) value of the cured layer (the entire liquid crystal layer) can be maintained in a desired range. It is not particularly limited.For example, the normal dispersion polymerizable liquid crystal compound may be included in a ratio of 0 to 60% by weight or more than 0% by weight and not more than 60% by weight. 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or It may be about 5% by weight or less.In this range, the cured layer (liquid crystal layer) can exhibit suitable reverse dispersion characteristics and transmittance characteristics.Therefore, the proportion of the normal dispersion polymerizable liquid crystal compound in the polymerizable liquid crystal composition is formed It may be within a range in which the above-mentioned positively dispersed polymerizable liquid crystal compound may be present in the above-mentioned range in the cured layer.

In the polarizing plate, a pressure-sensitive adhesive layer is present under the retardation layer. The pressure-sensitive adhesive layer may be used to attach the polarizing plate to a device, for example, an OLED panel. As the pressure-sensitive adhesive layer, various types of pressure-sensitive adhesives known for optics or polarizing plates may be used without limitation. This type of pressure-sensitive adhesive layer usually includes a base polymer and a crosslinking agent that crosslinks the base polymer, and is either a thermosetting type or a photocuring type. In general, as the base polymer for optics or polarizing plates, a pressure-sensitive adhesive layer including acrylic polymer, polyurethane, silicone polymer, rubber-based resin, or EVA-based resin is applied. may be selected and used.

The thickness of the polarizer, the retardation layer, and the pressure-sensitive adhesive layer, which are components of the polarizing plate of the present application described above, is not particularly limited, and an appropriate thickness may be selected from a known thickness range.

At least one of the components of the polarizing plate of the present application may include a dye. In the present specification, the term dye is meant to include a known coloring material as a so-called dye, pigment or pigment, and may be included in an appropriate position of the polarizing plate to control the absorption to transmittance spectrum of the polarizing plate in the above-described range. In view of the convenience of application, the dye may be included in the pressure-sensitive adhesive layer, but the location of the dye is not limited thereto. The type of dye that can be applied in the present application is not particularly limited, but a dye having a maximum absorption wavelength in the range of 500 nm to 700 nm from the viewpoint of the above-mentioned transmittance control may be applied. In another example, the maximum absorption wavelength is 510 nm or more, 520 nm or more, 530 nm or more, 540 nm or more, 550 nm or more, 560 nm or more, 570 nm or more, 580 nm or more, 590 nm or more, 600 nm or more, 610 nm or more, 620 nm or more, or 630 nm or more, or 690 nm or less. , 680 nm or less, 670 nm or less, 660 nm or less, 650 nm or less, 640 nm or less, 630 nm or less, 620 nm or less, 610 nm or less, 600 nm or less, 590 nm or less, 580 nm or less, or 570 nm or less. In one example, the maximum absorption wavelength of the dye may be in the range of 530 nm to 570 nm, 600 nm to 660 nm, or 630 nm to 660 nm. In the present application, azo-based dyes or pigments, metal-containing azo-based dyes or pigments, quinoline-based dyes or pigments, methine-based dyes or pigments, coumarin-based dyes or pigments, porphyrin-based dyes or pigments, azaporphyrin-based dyes or pigments, phthalocyanine Known as dyes or pigments, anthraquinone dyes or pigments, perylene dyes or pigments, squarylium dyes or pigments, benzoazole dyes or pigments, aminostyryl dyes or pigments, or disulfone dyes or pigments, etc. It is possible to select and use a dye or pigment having the maximum absorption wavelength from among the existing dyes or pigments.

The ratio of the dye may be selected at an appropriate level in consideration of a position to which the dye is applied or a desired absorption or transmittance spectrum of the polarizing plate. For example, when the dye is applied to the pressure-sensitive adhesive layer, the proportion of the dye may be about 0.001 to 5% by weight in the pressure-sensitive adhesive, but is not limited thereto. In another example, the ratio is 0.003 wt% or more, 0.005 wt% or more, 0.007 wt% or more, 0.009 wt% or more, or 0.01 wt% or more, or 4.8 wt% or less, 4.6 wt% or less, 4.4 wt% or less, 4.2 wt% or less, 4 wt% or less, 3.8 wt% or less, 3.6 wt% or less, 3.4 wt% or less, 3.2 wt% or less, 3 wt% or less, 2.8 wt% or less, 2.6 wt% or less, 2.4 wt% or less, 2.2 wt% or less or less, 2 wt% or less, 1.8 wt% or less, 1.6 wt% or less, 1.4 wt% or less, 1.2 wt% or less, 1 wt% or less, or 0.8 wt% or less wt% or less, 0.6 wt% or less wt%, 0.4 wt% % or less, 0.2 wt% or less, 0.1 wt% or less, 0.08 wt% or less, 0.06 wt% or less, or 0.05 wt% or less.

The polarizing plate may have various other structures as long as it basically includes the polarizer, the retardation layer, and the pressure-sensitive adhesive layer.

For example, the polarizing plate may include an additional layer (hereinafter, an outer layer) laminated on the upper side of the polarizer, that is, on a surface opposite to the surface of the polarizer facing the retardation layer.

The type of the outer layer may include, but is not limited to, a polarizer protective film, a hard coating layer, a retardation film, an antireflection layer, or a liquid crystal coating layer. As the outer layer, for example, various types of films used to constitute an optical film such as a polarizing plate in the industry may be used without limitation.

For example, the outer layer may be an optical film having an in-plane retardation of 10 nm or less with respect to a wavelength of 550 nm. The optical film may be a protective film of the polarizer. As the protective film, various films known in the art may be applied.

The outer layer may also be a retardation layer having a quarter-wave phase retardation characteristic. Such a retardation layer may be configured by using a retardation film or a liquid crystal coating layer among the above-described outer layers. Therefore, the polarizing plate is laminated on the opposite surface of the surface facing the retardation layer of the polarizer, and the in-plane retardation with respect to the 550 nm wavelength may further include an optical film (retardation layer) in the range of 90 nm to 300 nm have. In another example, the in-plane retardation of the retardation layer may be 100 nm or more, 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, or 130 nm or more. In addition, the in-plane retardation is 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, or 145 nm or less.

The above-mentioned outer layer may be a single layer or a multilayer structure. As an example of the single-layer structure, a single-layer structure of the polarizer protective film or a single-layer structure of a retardation film that is a retardation layer having the quarter-wave retardation characteristic may be exemplified, and the multilayer structure includes the polarizer protective film and / or a structure in which a hard coating layer, a liquid crystal coating layer and/or an anti-reflection layer having a quarter-wave retardation characteristic are formed on the retardation film may be exemplified, and the hard coating layer, liquid crystal having a quarter-wave retardation characteristic Any one of the coating layer and the antireflection layer may be present, or two or more layers may be present in multiple layers.

The polarizing plate may further include an additional layer (hereinafter, referred to as a lower layer) under the retardation layer, for example, between the retardation layer and the pressure-sensitive adhesive layer. In a state in which the lower layer is present, an outer layer such as a hard coating layer or a low reflection layer may be present on the upper portion of the polarizer, and a protective film may be present on one side or both sides of the polarizer.

As the type of the lower layer, a retardation layer may be exemplified.

When the retardation layer is used as the lower layer, a layer satisfying the refractive index relationship of Equation 7 or 8 below may be applied as the layer. Due to the addition of such a layer, the polarizing plate may exhibit desired characteristics even with respect to light incident in an oblique direction.

[Equation 7]

nx = ny < nz

[Equation 8]

nx > ny and nz > ny

In Equations 7 and 8, nx, ny and nz are as defined in Equations 1 to 3.

The polarizing plate may further include an optical film, which is a retardation layer, which is the lower layer, is present under the retardation layer and has a thickness direction retardation within a range of 10 to 400 nm. The optical film may be a retardation layer satisfying the refractive index relationship of Equation 7 or 8 above.

The upper limit of the thickness direction retardation of the optical film is 370 nm or less, 350 nm or less, 330 nm or less, 300 nm or less, 270 nm, 250 nm, 240 nm, 230 nm, 220 nm, 200 nm, 190 nm, 180 in another example. nm, 170 nm, 160 nm, 155 nm, 150 nm, 130 nm, 120 nm, 110 nm, 100 nm, 80 nm or 70 nm. In addition, the lower limit of the thickness direction retardation of the optical film may be 5 nm, 10 nm, 20 nm, 40 nm, 50 nm, 90 nm, 100 nm, 110 nm, 120 nm or 150 nm in another example. By adjusting the retardation in the thickness direction of the optical film as described above, it is possible to provide a polarizing plate having excellent reflection characteristics and luminous characteristics, particularly, reflective characteristics and luminous characteristics at an inclination angle.

When the optical film is an optical film satisfying Equation 8, the in-plane retardation is, for example, more than 0 nm, 300 nm or less, 290 nm or less, 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, 240 nm or less, 230 nm or less, 220 nm or less, 210 nm or less, 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, 160 nm or less, 150 nm or less, 140 nm or less, 130 nm or less can be 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less have.

When the optical film is an optical film satisfying Equation 8, the optical film may be disposed such that its slow axis is perpendicular or horizontal to the absorption axis of the polarizer. As used herein, the terms vertical, orthogonal, horizontal or parallel mean substantially vertical, orthogonal, horizontal or parallel in a range that does not impair the desired effect. Accordingly, each of the above terms may include, for example, an error within ±15 degrees, within ±10 degrees, within ±5 degrees, or within ±3 degrees.

In another example, when the optical film is an optical film satisfying Equation 8, the slow axis may be arranged such that the absorption axis of the polarizer forms an angle within the range of about 30 degrees to 60 degrees. The angle may be 35 degrees or more or 40 degrees or more in another example, and may be 55 degrees or less or 50 degrees or less.

In the polarizing plate, a separate layer may or may not exist between the polarizer and the retardation layer.

In the case where there is no separate layer between the polarizer and the retardation layer, the polarizer and the retardation layer are directly attached. In this case, a layer for bonding the polarizer and the retardation layer, for example, an adhesive layer , there may be no other layers except for the adhesive layer and/or the primer layer. Even when a separate layer exists or does not exist between the polarizer and the retardation layer, at least a birefringence layer may not exist between the polarizer and the retardation layer. In this case, the birefringent layer means a layer having at least one of in-plane retardation and thickness-direction retardation of 10 nm or more. For example, the polarizing plate is present between the polarizer and the retardation layer, the in-plane retardation with respect to the 550 nm wavelength is 5 nm or less, and the thickness direction retardation with respect to the 550 nm wavelength is in the range of -60 nm to 0 nm. It may further include a film, and such an optical film may be, for example, a protective film of a polarizer.

In the present application, there is no particular limitation on the thickness of the outer layer or the lower layer, and a thickness within an appropriate range may be selected according to the purpose.

The application also relates to a display device. An exemplary display device may include the polarizing plate.

In one example, the display may be an organic light emitting diode (OLED) display, and in this case, the display may include an OLED panel and the polarizing plate attached to the OLED panel. The polarizing plate may be attached to the light exit surface of the OLED panel. The polarizing plate may be attached to the OLED panel by an adhesive layer included in the polarizing plate.

The type of the OLED panel is not particularly limited, but a WRGB type OLED panel may be applied as the OLED panel in that a polarizing plate may be applied to exhibit optimal performance.

The specific structure of the display device is not particularly limited as long as the above-described polarizing plate of the present application is applied, and a known OELD panel may be applied.

The present application is applied to an OLED panel, particularly a WRGB type OLED panel, so that 10000k white can be realized while minimizing driving energy for blue, red and/or green devices, and OLED device It is possible to provide a polarizing plate capable of exhibiting high luminance and excellent color reproducibility.

1 is an exemplary cross-sectional view of a polarizing plate of the present application.
2 is a diagram for explaining the x-axis, y-axis, and z-axis of the retardation layer.

Hereinafter, the present application will be described in detail through Examples and Comparative Examples, but the scope of the present application is not limited by the following variable transmittance device.

1. Method of measuring transmittance of a polarizing plate

The transmittance for each wavelength of the polarizing plate was evaluated by applying Shimadzu's UV-3600 equipment and scanning at a medium speed for a wavelength range of 380 to 780 nm.

2. Method of measuring the maximum absorption wavelength of a dye

The maximum absorption wavelength of the dye was evaluated by measuring the transmittance of the wavelength in the 380 nm to 780 nm range by applying Shimadzu's UV-3600 equipment.

3. How to evaluate the luminance of a display

The luminance of the OLED panel to which the polarizing plate of Examples or Comparative Examples is attached is determined by applying SPTEC's Spectroradiometer equipment (product name: ELABO-605L) in the state that the device displays 10000k of white color. were evaluated accordingly.

4. Evaluation method of color reproducibility

The color gamut of the OLED panel to which the polarizing plate of the Example or Comparative Example is attached was evaluated according to the color measurement method at the time of RGB monochromatic output by applying ELABO-605L equipment of SP Tech.

Example 1.

A polarizer was manufactured by using a poly(vinyl alcohol) (PVA) film (Nippon Synthetic Co., Ltd., M4504L) having a thickness of about 45 μm as a raw film. First, a swelling treatment was performed on the raw film. The swelling treatment was performed by immersing the raw film in pure water at a temperature of 25° C. for 30 seconds. In the process of swelling treatment, stretching was performed so as to be stretched to about 28% of the final draw ratio. Then, a dyeing treatment was performed using a dye solution in which iodine (I2) and potassium iodide (KI) were dissolved in pure water at concentrations of 0.2 wt% and 2.5 wt%, respectively. The dyeing treatment was performed by immersing the raw film in the dyeing solution at 28° C. for about 2 minutes. In this process, stretching was carried out so as to be stretched to about 40% of the final stretch ratio. Thereafter, the dyed PVA film was immersed in an aqueous solution (crosslinking solution) at 35° C. containing 1% by weight of boron and 3% by weight of potassium iodide for 60 seconds for crosslinking treatment. Then, the raw film was stretched. Stretching was performed in an aqueous solution (treatment solution) containing about 3 wt% of boric acid and potassium iodide, respectively. The temperature of the treatment liquid was about 50°C. Then, the stretched film was washed with an aqueous solution. At this time, the temperature of the aqueous solution was about 25° C., and the washing treatment was performed within 1 minute. Thereafter, the film was dried to prepare a PVA polarizer (thickness: 27 μm, total draw ratio: 5.4 times).

A TAC (triacetyl cellulose) protective film was attached to one side of the PVA polarizer with an adhesive, and a retardation layer and an adhesive layer were sequentially formed on the other side of the PVA polarizer. As the retardation layer, a COP (cycloolefin polymer) film having an in-plane retardation of about 137.5 nm for light having a wavelength of 550 nm was applied, and as the pressure-sensitive adhesive layer, a conventional acrylic adhesive for optics was applied. The acrylic pressure-sensitive adhesive includes a hydroxyl group-containing acrylic polymer and an isocyanate crosslinking agent.

As a dye in the acrylic pressure-sensitive adhesive, an azo dye (manufacturer: Meghmani Dyes and Intermediates Ltd, product name: Pink 5BLG) having a maximum absorption wavelength in the range of about 530 nm to 570 nm was included in a ratio of about 0.0153 wt%. The dye is diluted in a solvent (ethyl acetate) to contain the dye in the above ratio, mixed with the adhesive coating solution and defoamed, and then the mixture is coated on the release-treated surface of the release film (release PET film), dried and cured to form an adhesive layer was formed. A polarizing plate was manufactured by attaching the COP retardation layer to one surface of a PVA polarizer and to a surface to which the TAC protective film is not attached, and laminating the pressure-sensitive adhesive layer to one surface thereof. In the above process, the slow axis of the COP retardation layer and the absorption axis of the polarizer formed an angle of approximately 45 degrees.

Example 2.

As a dye in the acrylic pressure-sensitive adhesive layer, a pigment having a maximum absorption wavelength in the range of about 530 nm to 570 nm (Manufacturer: Wooksung Chemical, Product Name: Pink CP1122) is included in the same as Example 1, except that about 0.6375 wt% A polarizing plate was manufactured.

Example 3.

As a dye in the acrylic pressure-sensitive adhesive layer, an anthraquinone-based dye (manufacturer: Yedam Chemical, product name: Blue S-3R) having a maximum absorption wavelength in the range of about 600 nm to 660 nm is included in a ratio of about 0.0331 wt%, except that A polarizing plate was prepared in the same manner as in Example 1.

Comparative Example 1.

A polarizing plate was prepared in the same manner as in Example 1, except that an acrylic pressure-sensitive adhesive layer to which no dye was applied was used.

The transmittance of each wavelength of the polarizing plate of Examples and Comparative Examples is summarized in Table 1 below.

450nm 550nm 600nm 650nm Example 1 40.6 42.0 43.4 44.4 Example 2 40.5 41.9 43.6 44.4 Example 3 40.8 42.5 41.9 43.3 Comparative Example 1 40.8 43.8 43.8 44.4

While the polarizing plates of Examples and Comparative Examples were respectively attached to the light exit surface of the WRGB type OLED panel, 10000k white was displayed, and the luminance was measured and summarized in Table 2 below.

Example 1 Example 2 Example 3 Comparative Example 1 luminance 102.5% a.u. 101.9% a.u. 102.3% a.u. 100% a.u.

From the results in Table 2, it can be confirmed that higher luminance can be secured during 10000k white display through the application of the polarizing plate of the embodiment of the present application. In particular, in the case of Comparative Example 1, a white device, a blue device, and a red or white device, a blue device, and a green device of the WRGB type OLED panel was simultaneously driven to display the 10000k white color, but in the case of the embodiment, only white and blue devices were applied to display the 10000k white color even under much lower driving energy. In addition, in the case of Examples 1 to 3, it was confirmed that all of them exhibited the same color gamut based on DCI or a level of a decrease of 0.1%, so that the color gamut could also be stably secured.

100: polarizer
200: retardation layer
300: adhesive layer

Claims (15)

polarizer; a retardation layer formed under the polarizer; and a pressure-sensitive adhesive layer formed under the retardation layer, the polarizing plate satisfying the following formula A:
[Formula A]
100 ≤ 100×I ₅₅₀ /I ₄₅₀ < 107
In Equation A, I ₅₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 550 nm, and I ₄₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 450 nm. The polarizing plate according to claim 1, further satisfying the following formula B:
[Formula B]
90 ≤ 100×I ₆₀₀ /I ₅₅₀ < 115
In Equation B, I ₅₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 550 nm, and I ₆₀₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 600 nm. According to claim 1, wherein the polarizing plate further satisfies the following formula C:
[Formula C]
95 ≤ 100×I ₆₅₀ /I ₆₀₀ < 115
In Equation C, I ₆₅₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 650 nm, and I ₆₀₀ is the transmittance of the polarizing plate with respect to light of a wavelength of 600 nm. The polarizing plate according to claim 1, wherein the transmittance for light having a wavelength of 450 nm is in the range of 30% to 50%. The polarizing plate according to claim 1, wherein the polarizer is a PVA-based linear absorption type polarizer. The polarizing plate according to claim 1, wherein the retardation layer has a refractive index relationship according to any one of Equations 1 to 3:
[Formula 1]
nx > ny = nz
[Formula 2]
nx > ny > nz
[Equation 3]
nx > ny and nz > ny
In Equations 1 to 3, nx, ny, and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively. The polarizing plate according to claim 1, wherein the retardation layer has an in-plane retardation of light with a wavelength of 550 nm in a range of 90 nm to 300 nm. The polarizing plate according to claim 1, wherein the retardation layer satisfies the following Equation 6:
[Equation 6]
R(450)/R(550) < R(650)/R(550)
In Equation 6, R(450) is the in-plane retardation of the retardation layer with respect to light of a wavelength of 450 nm, R(550) is the in-plane retardation of the retardation layer with respect to light of a wavelength of 550 nm, and R(650) is 650 It is the in-plane retardation of the retardation layer with respect to the light of the wavelength of nm. The polarizing plate according to claim 1, wherein the slow axis of the retardation layer and the absorption axis of the polarizer form an angle within the range of 30 degrees to 60 degrees. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer includes a dye. The polarizing plate according to claim 10, wherein the maximum absorption wavelength of the dye is in the range of 500 nm to 700 nm. The polarizing plate according to claim 10, wherein the maximum absorption wavelength of the dye is within the range of 530 nm to 570 nm, within the range of 600 nm to 660 nm, or within the range of 630 nm to 660 nm. The polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer contains a dye in a proportion of 0.001 wt% to 5 wt%. An OLED display comprising an OLED panel and the polarizing plate of any one of claims 1 to 13 attached to the OLED panel. The OLED display according to claim 14, wherein the OLED panel is a WRGB type OLED panel.

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