KR102063205B1 - Polarizing plate and light emitting diode display comprising the same - Google Patents

Abstract

A polarizer comprising a polarizer, a first protective layer laminated on one side of the polarizer, and a second protective layer laminated on the other side of the polarizer, the polarizer comprises a polyvinyl alcohol copolymerized polyolefin, the polarizing plate is A polarizing plate having a reflectance of 0.35% to 0.45%, a bc value of -8 to -12, a polarization degree of 98.5% to 99.5%, and a light transmittance of 44.5% to 45.5% is provided, and a light emitting display device including the same.

Description

POLARIZING PLATE AND LIGHT EMITTING DIODE DISPLAY COMPRISING THE SAME}

The present invention relates to a polarizing plate and a light emitting display device including the same.

The structure of a polarizing plate consists of surface treatment, a protective film, a polarizing element, and a retardation film. The retardation film may be a single film having reverse wavelength dispersion, or a two film without reverse wavelength dispersion, and a liquid crystal having the same retardation performance may be used.

When the light of the panel of the organic light emitting diode display (OLED) is reflected by the external light, the visibility generated by the reflection of the external light is reduced in the color appearing in the panel of the organic light emitting diode display (OLED). In order to prevent a decrease in visibility due to such external light, a polarizing plate is used as an external light antireflection film.

The principle of the external light antireflection polarizer is that the external light primarily linearly polarized by the polarizer passes through the retardation film, and the external light changed to circular polarization is reflected by the OLED panel to change to circular polarization in the opposite direction. External light is rotated 90 degrees to prevent the polarizer from passing through.

 In order to improve the reflection reduction efficiency of the anti-reflective polarizing plate of an organic light emitting diode display (OLED), the phase difference is generally primarily improved by reversing the wavelength dispersion of the retardation film. It is mostly to improve the film.

In recent years, the technique which laminated | stacks a liquid crystal layer instead of a polymer film as a retardation layer to a polarizer is introduced. The liquid crystal layer can reduce the thickness of the polarizing plate compared to the polymer film. Even in the case of including the liquid crystal layer, the reflectance, the color value bc value, and the like must fall within an appropriate range to prevent the screen visibility decrease due to external light and improve the screen color.

Background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2013-101301.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarizing plate capable of preventing a decrease in screen visibility due to external light in a light emitting device display device having a high light transmittance, a high degree of polarization, and a low reflectance.

Another object of the present invention is to provide a polarizing plate capable of improving color of a display screen due to a low color value bc.

Another object of the present invention is to provide a polarizing plate having excellent durability.

The polarizing plate of the present invention comprises a polarizer, a first protective layer laminated on one side of the polarizer, and a second protective layer laminated on the other side of the polarizer, the polarizer comprises a polyvinyl alcohol copolymerized polyolefin, The polarizing plate may have a reflectance of 0.35% to 0.45%, a bc value of -8 to -12, a polarization degree of 98.5% to 99.5%, and a light transmittance of 44.5% to 45.5%.

The light emitting display device of the present invention may include the polarizing plate of the present invention.

The present invention provides a polarizing plate capable of preventing a decrease in screen visibility due to external light in a light emitting device display device having a high light transmittance, a high degree of polarization, and a low reflectance.

The present invention provides a polarizing plate capable of improving a display screen color because the color value bc is low.

The present invention provides a polarizing plate having excellent durability.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

The present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the present specification, "Re" is a value calculated by Equation 1 below.

<Equation 1>

Re = (nx-ny) × d

(In Formula 1, nx and ny are refractive indexes in the x-axis and y-axis directions of the film at a wavelength of 550 nm, respectively, and d is the thickness (unit: nm) of the film).

In the present specification, "polarization rate change rate" is a value calculated by the following equation.

<Equation 2>

Change rate of polarization degree = ｜ P ₂ -P ₁ ｜

(In Formula 2, P ₁ is the initial polarization degree (unit:%) of the polarizing plate,

P ₂ is the degree of polarization (unit:%) after the polarizing plate is left for 500 hours at 65 ° C. and 95% relative humidity. The "initial polarization degree" means the polarization degree of the polarizing plate before the polarizing plate is left for 500 hours at 65 ° C and 95% relative humidity.

In the present specification, the "bc value" of the polarizing plate is measured using a reference polarizing plate having a polarization degree of 98% or more, and orthogonal to the absorption axis of the reference polarizing plate and the polarizing unit of the polarizing plate of the polarizing plate of the present invention, and CIE LAB for a wavelength of 380 to 780 nm. It may be an orthogonal bc value measured by the color coordinate standard. The "reference polarizing plate" may be in the measuring device of the orthogonal bc value.

In the present specification, the "reflectivity" of the polarizing plate is a specimen prepared by laminating an organic light emitting device panel on the second phase difference layer of the polarizing plate, and the SCE reflection mode (light source: D65) with a spectrophotometer (eg, Konica Minolta, CM-3600A) Light source, light source aperture: Φ 8 mm, measurement viewing angle: 10 °) means the lowest value of the reflectance measured in the section of wavelength 360nm to 740nm.

MEANS TO SOLVE THE PROBLEM In the polarizing plate used for the light emitting element display device, this invention improved the reflectance, the light transmittance, and also the polarization degree and the color value bc value were remarkably improved by including the polyvinyl alcohol copolymerized with the polyolefin which has the following specific physical property as a polarizer. It confirmed and completed this invention.

Hereinafter, a polarizer according to an embodiment of the present invention will be described with reference to FIG. 1.

Referring to FIG. 1, the polarizer 10 may include a polarizer 300, a first protective layer 100 stacked on one surface of the polarizer 300, and a second protective layer 200 stacked on the other surface of the polarizer 300. It may include. Although not shown in FIG. 1, an adhesive layer formed of an adhesive layer, for example, a pressure sensitive adhesive (PSA), is formed on the other surface of the second protective layer 200 (the surface on which the polarizer is not laminated), thereby forming the polarizer as an organic light emitting device. It can be laminated to the panel.

Polarizer

The polarizer 300 may polarize the external light and transmit the polarized light through the second protective layer 200 to improve visibility when applied to the light emitting device display device.

The polarizer 300 includes polyvinyl alcohol copolymerized with polyolefin having a weight average molecular weight (Mw) of 90,000 to 150,000. The polarizer 300 may be made of a polyvinyl alcohol film copolymerized with a polyolefin having a weight average molecular weight (Mw) of 90,000 to 150,000 and a Re of 1 nm to 35 nm at a wavelength of 550 nm. In the weight average molecular weight and Re range, a polarizing plate having a reflectance of 0.35% to 0.45%, a bc value of -8 to -12, a polarization degree of 98.5% to 99.5%, and a light transmittance of 44.5% to 45.5% may be manufactured. In one embodiment, the polarizing plate may have a bc value of −8 to −11 and a degree of polarization of 98.9% to 99.5%.

Even if the film is dyed after high dyeing by producing a polarizer from a polyvinyl alcohol film copolymerized with a polyolefin having a weight average molecular weight of 90,000 to 150,000, there is no film breakage, and thus 98.5% to 99.5 even at a high light transmittance of 44.5% to 45.5%. % High degree of polarization can be expressed. By producing a polarizer from a polyvinyl alcohol film copolymerized with a polyolefin having a Re of 1 nm to 35 nm at a wavelength of 550 nm, the film is already stretched, so that the film can be dyed and stretched at a higher draw ratio than at the time of further drawing. Even in the high light transmittance of 98.5% to 99.5% can exhibit a high degree of polarization. In addition, since the film is already stretched at a predetermined draw ratio before dyeing, the bc value may be -8 to -12 by further stretching and affecting the arrangement of iodine and the like during iodine dyeing. When the Re value is in the above range, due to the pre-stretched orientation effect, it may have a higher degree of orientation than the polarizing plate of the magnification stretched in the existing process, and as the weight average molecular weight increases, high orientation is possible without breaking in the stretching process at a high temperature. High orientation of the polarizing plate can result in a decrease in reflectance by expressing a high degree of polarization at the same degree of polarization.

Preferably, the polyvinyl alcohol copolymerized with polyolefin has a weight average molecular weight of 90,000 to 140,000, and the polyvinyl alcohol film copolymerized with polyolefin has Re of 1 nm to 35 nm, preferably 5 nm to 35 nm, more preferably at a wavelength of 550 nm. May be 10 nm to 30 nm. Through this, even if drawn at 60 ℃ or more there may be no problem such as melting the film. In particular, the polarizer of the present invention, when laminating the liquid crystal layer with the first retardation film and the second retardation film on the other side of the polarizer as described below, the reflectance, polarization degree, bc value, light transmittance of the polarizing plate in the scope of the present invention Can be reached. As a result, it is possible to prevent a decrease in screen visibility due to external light in the light emitting display device and to improve display color.

In addition, in the polarizing plate of the present invention, the polarization degree change rate according to Equation 2 may be 5% or less. Within this range, the reliability of the polarizing plate can be improved.

The polyvinyl alcohol copolymerized with polyolefin may have a number average molecular weight (Mn) of 50,000 or more, for example, 50,000 to 60,000. In the above range, there may be a high temperature stretching and a high orientation effect by the molecular weight rise.

The polyvinyl alcohol copolymerized with polyolefin may have a softening point of 60 ° C to 70 ° C, preferably 65 ° C to 68 ° C.

The polyolefin may comprise polyethylene, polypropylene, polybutylene and the like, preferably polyethylene. Polyvinyl alcohol copolymerized with polyolefin may be prepared by conventional methods known to those skilled in the art. For example, polyvinyl alcohol copolymerized with polyolefin may be prepared by hydrolyzing a copolymer of polyvinyl acetate and polyolefin.

The polarizer 300 may have a crystallinity of 40% or more, for example, 41% to 50%. In the above range, it is possible to improve the durability of the polarizing plate.

The polarizer 300 may have a thickness of 5 μm to 50 μm. It can be used in the organic light emitting display device in the above range.

The polarizer 300 may be manufactured by dyeing and stretching a polyvinyl alcohol film copolymerized with polyolefin. In the manufacturing method of the polarizer of this invention, the order of dyeing and extending | stretching is not restrict | limited. That is, the polyvinyl alcohol film may be stretched after dyeing, or after stretching, dyeing may be performed, and the dyeing and stretching may be simultaneously performed.

Polyolefin Copolymerized The polyvinyl alcohol film copolymerized with polyolefin may have a thickness of 1 μm to 60 μm, specifically 3 μm to 60 μm, and may be used in the manufacture of a thin polarizer in the above range.

The polyvinyl alcohol film may be washed with water and swelled before dyeing and stretching. By washing the film with water, the foreign matter on the surface of the film can be removed. By swelling the film, it is possible to better dye or stretch the film. The swelling treatment can be performed by leaving the film in an aqueous solution of the swelling bath as known to those skilled in the art. The temperature and swelling treatment time of the swelling bath are not particularly limited. The swelling tank may further include boric acid, inorganic acids, surfactants, and the like, and their contents may be adjusted.

The dichroic substance may be dyed into the film by dyeing the film in a dichroic substance-containing dye bath. In the dyeing process, the film is immersed in the dyeing solution, and the dyeing solution may be an aqueous solution containing an iodine-based dye. Specifically, the iodide dye may be potassium iodide, hydrogen iodide, lithium iodide, sodium iodide, zinc iodide, lithium iodide, aluminum iodide, lead iodide, copper iodide, or the like. The dyeing solution may be an aqueous solution containing between 1 ml / mol and 10 ml / mol of the dichroic substance. In this range, it can be used in a display with a degree of polarization.

The temperature of the dye bath may be 20 to 45 ℃ and the dye bath bath time may be 10 seconds to 300 seconds. It is possible to implement a polarizer having a high degree of polarization in the above range.

By stretching the polyvinyl alcohol film copolymerized with the polyolefin salted in a drawing bath, the polyvinyl alcohol film copolymerized with the polyolefin may have a dichroic material and be polarized. Specifically, the stretching may be both a dry stretching and a wet stretching method. Dry stretching may be interroll stretching, compression stretching, hot roll stretching, and the like, and wet stretching may be performed in a wet stretching bath containing water. The wet drawing tank may further increase the drawing effect by further including boric acid. Boric acid may be included in 3 to 5% by weight of the wet drawing bath. In the above range, there may be a durability improving effect. Stretching may be carried out at 60 ° C. or higher, for example 63 ° C. or higher, for example 63 ° C. to 80 ° C. Within this range, high transmittance and high polarization can be achieved.

The film may be stretched at a predetermined draw ratio, and in particular, the total draw ratio may be stretched to be 5 to 7 times, specifically 5.5 to 6.5 times, to prevent cutting, wrinkles, etc. of the film drawn in the above range. It is possible to implement a polarizer having high polarization and light transmittance. Although extending | stretching may be extended | stretched by 1-stage extending | stretching as uniaxial stretching, it can also prevent fracture, although manufacturing a thin polarizer by multistage extending | stretching, such as 2-stage and 3-stage stretching.

In the above description, the film is dyed and stretched, but the dyeing and stretching of the dichroic material may be performed in the same reactor.

The stretched film before or after the dyeing may be crosslinked in a crosslinking bath. Crosslinking is a process of making the dichroic substance more strongly dyed to the film, and boric acid may be used as the crosslinking agent. In order to increase the crosslinking effect, a phosphate compound, potassium iodide, or the like may be further included. The crosslinking bath may be an aqueous solution containing 3 to 5% by weight of boric acid. In the above range, there may be a more durable effect. Crosslinking can be performed at 30 ° C to 60 ° C. In the above range, there may be an effect of preventing the break of the film at the time of stretching in a high temperature drawing tank.

The dyed and stretched film may be complementary in a complementary color bath.

Complementary color treatment is to immerse the dye-formed and stretched film in a complementary color bath containing a complementary color liquid containing potassium iodide. Through this, the color value of the polarizer can be lowered and the durability of the polarizer can be improved. The temperature of the complementary color bath may be 20 ° C to 45 ° C and the complementary color bath dipping time of the film may be 300 seconds or less, for example, 10 seconds or less. Complementary color may be an aqueous solution containing 1 to 5% by weight potassium iodide. In the above range, there may be an effect of reducing the degree of polarization decrease at 65 ℃ and 95% relative humidity.

First protective layer

The first protective layer 100 may be formed on one surface of the polarizer 300 to protect the polarizer 300 and increase mechanical strength of the polarizer. The first protective layer 100 may include one or more of an optically transparent, protective film or protective coating layer.

When the first protective layer 100 is a protective film type, it may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, additional stretching processes may be added. The resin may include a cellulose ester resin including triacetyl cellulose, a cyclic polyolefin resin including a cyclic olefin polymer (COP), a polycarbonate resin, a polyethylene terephthalate (PET), and the like. Polyacrylate resin containing polyester resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, acyclic-polyolefin resin, polymethyl methacrylate resin, etc. which are mentioned, It may include one or more of polyvinyl alcohol-based resin, polyvinyl chloride-based resin, polyvinylidene chloride-based resin.

When the first protective layer 100 is a protective coating layer type, good adhesion, transparency, mechanical strength, thermal stability, moisture barrier, and durability to the polarizer 100 may be improved. In one embodiment, the protective coating layer for the first protective layer 100 may be formed of an active energy ray curable resin composition comprising an active energy ray curable compound and a polymerization initiator. The active energy ray curable compound may include at least one of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy compound having at least one epoxy group in a molecule, or an oxetane compound having at least one oxetane ring in a molecule. The radically polymerizable curable compound may be a (meth) acrylic compound having at least one (meth) acryloyloxy group in a molecule.

The thickness of the first protective layer 100 may be 5 μm to 200 μm, specifically 30 μm to 120 μm, and 50 μm to 100 μm for the protective film type, and 5 μm to 50 μm for the protective coating layer type. Can be It can be used in the organic light emitting display device in the above range.

Although not shown in FIG. 1, a functional coating layer, for example, a hard coating layer, an anti-fingerprint layer, an antireflection layer, or the like may be further formed on the upper surface of the first protective layer 100. In addition, although not shown in FIG. 1, when the first protective layer 100 is a protective film type, an adhesive layer may be further formed between the first protective layer 100 and the polarizer 300. The adhesive layer may be formed of a conventional polarizing plate adhesive, for example, an aqueous adhesive, a photocurable adhesive, or a pressure sensitive adhesive.

Second protective layer

The second protective layer 200 may be formed on the other surface of the polarizer 300 to protect the polarizer 300 and increase the mechanical strength of the polarizer.

The second protective layer 200 may be optically transparent. Specifically, the second passivation layer 120 may have a total light transmittance of 90% or more, specifically 90% to 100% in the visible light region. Within this range, the light emitting display device can be used.

1 illustrates a case where the second protective layer 200 is a single layer, but the second protective layer 200 may be multiple layers.

The second protective layer 200 may include a retardation film to improve visibility of the polarizing plate. In one embodiment, the retardation film has a first wavelength at 550 nm, wherein Re is 225 nm to 350 nm, more specifically 225 nm to 300 nm, more specifically 230 nm to 250 nm, for example a lambda / 2 retardation film (HWP). It can be a retardation film. In one embodiment, the retardation film has a second phase difference at a wavelength of 550 nm, wherein Re is 100 nm to 220 nm, more specifically 100 nm to 180 nm, more specifically 110 nm to 130 nm and is, for example, λ / 4 quarter wave plate (QWP). It can be a film. The first retardation film or the second retardation film may be used alone or in a lamination. In the above range, when used in a light emitting display device including a light emitting element it may be effective to reduce the side color shift.

The retardation film may provide an optical compensation effect when used in a polarizing plate, and may be an optically transparent resin film or a liquid crystal film. In one embodiment, the retardation film may be a resin film formed of an optically transparent resin. The resin may include the resin described in the first protective layer, or may include a film prepared after the modification of the resin. The modification may include, but is not limited to, copolymerization, branching, crosslinking, or including heterogeneous molecules. In this case, the retardation film may be the same or different from the first protective layer 100, thickness, material, and the like. In another embodiment, the retardation film may be an optically transparent liquid crystal film. In another embodiment, the retardation film may be a liquid crystalline coating layer. The liquid crystal film and the liquid crystal coating layer may be formed of a liquid crystal composition. The liquid crystal composition exhibits liquid crystallinity, and examples of the liquid crystals include nematic liquid crystal phases, smectic liquid crystal phases, cholesteric liquid crystal phases, and cylindrical liquid crystal phases. The liquid crystal film or liquid crystalline coating layer may have a thickness of 1 μm to 100 μm, specifically 1 μm to 50 μm, and more specifically 1 μm to 10 μm. It can be used in the optical display device in the above range.

In one embodiment, the second protective layer may be a second retardation film. In another embodiment, the second protective layer may be sequentially laminated the first retardation film and the second retardation film from the polarizer, in which case the first retardation film and the second retardation film is a conventional pressure-sensitive adhesive, such as a pressure-sensitive adhesive ( PSA (pressure sensitive adhesive) can be stacked on each other.

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

The light emitting display device of the present invention may include the polarizing plate of the present invention. The light emitting display device may be a device including a light emitting device. The light emitting device includes an organic or organic-inorganic light emitting device, and means a device including light emitting diodes (LEDs), organic light emitting diodes (OLEDs), quantum dot light emitting diodes (QLEDs), and phosphors. can do. For example, the light emitting display device may include an organic light emitting display device.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Specific specifications of the components used in the following Examples and Comparative Examples are as follows.

(1) Material of the polarizer: material of Table 1 below

(2) First protective layer: triacetyl cellulose film (KA25-HC, Konica, thickness: 32 ± 5㎛) with a hard coating layer

(3) Second protective layer: A first phase difference film having a Re of 240 ± 6 nm at a wavelength of 550 nm (QLAA218, FUJI, liquid crystal layer, thickness: 2 ± 1 μm), and a second phase difference having a Re of 120 ± 6 nm at a wavelength of 550 nm. Film (QLAB218, FUJI Corporation, liquid crystal layer, thickness: 1 to 2㎛)

Example  One

As the polyvinyl alcohol film copolymerized with polyethylene, the materials shown in Table 1 below were used. A polyvinyl alcohol film copolymerized with polyethylene washed with water at 25 ° C was swelled in a swelling bath of 30 ° C water. The film passed through the swelling bath was treated for 65 seconds in a dye bath at 30 ° C. containing an aqueous solution containing 1 ml / mol potassium iodide.

The film passed through the dye bath was passed through a wet crosslinking bath which was a 30 ° C. aqueous solution containing 3% by weight of boric acid. The film passed through the crosslinking bath was stretched in an aqueous 65 ° C. solution containing 3% by weight of boric acid, but was drawn to have a total draw ratio of 6 times.

The film passed through the stretching bath was treated for 10 seconds or less in a complementary bath containing a complementary solution which was a 30 ° C. aqueous solution containing 4.5% by weight of potassium iodide.

The film passed through the complementary color bath was washed with water and dried to prepare a polarizer (thickness: 18 μm).

The first protective layer was bonded to one surface of the manufactured polarizer using an adhesive (Z-320, Nippon Goshei). The first phase difference film and the second phase difference film were sequentially laminated on the other surface of the polarizer using an acrylic pressure-sensitive adhesive to prepare a polarizing plate.

Example  2

As a polyvinyl alcohol film copolymerized with polyethylene, the materials shown in Table 1 below were used. Polarizing plate manufacture was produced similarly to Example 1.

Comparative example  One

As the polyvinyl alcohol (PVA) film, the materials shown in Table 1 below were used. The polyvinyl alcohol film washed with 25 degreeC water was swelled in the swelling tank of 25 degreeC water. The film passed through the swelling bath was treated for 65 seconds in a dye bath at 30 ° C. containing an aqueous solution containing 1 ml / mol potassium iodide. The film passed through the dye bath was passed through a wet crosslinking bath which was a 30 ° C. aqueous solution containing 3% by weight of boric acid. The film passed through the crosslinking bath was stretched in an aqueous solution at 53 ° C. containing 3% by weight of boric acid, but was drawn to have a total draw ratio of 6 times. The film passed through the stretching bath was treated for 10 seconds or less in a complementary bath containing a complementary solution which was a 30 ° C. aqueous solution containing 4.5% by weight of potassium iodide. The film passed through the complementary color bath was washed with water and dried to prepare a polarizer (thickness: 22 mu m). A polarizing plate was manufactured in the same manner as in Example 1.

Comparative example  2

As the polyvinyl alcohol (PVA) film, the materials shown in Table 1 below were used. A polyvinyl alcohol film was subjected to the same method as in Example 1. In the manufacturing process, the polyvinyl alcohol film was melted, and thus the polarizer and the polarizing plate could not be manufactured.

Furtherance Weight average molecular weight Re
(nm) thickness
(Μm) Product name, manufacturer Example 1 PVA-PE 110,000 30 45 VF-TS # 4500,
Kuraray Example 2 PVA-PE 90,000 10 30 VF-PE # 3000,
Kuraray Comparative Example 1
Comparative Example 2 PVA 90,000 10 60 VF-PS # 6000,
Kuraray

* In Table 1, PVA-PE is a polyvinyl alcohol film copolymerized with polyethylene, and PVA is a polyvinyl alcohol film (no polyethylene).

* Re in Table 1 was measured at a wavelength of 550 nm using Axoscan (AxoMetric, Inc.) for a polyvinyl alcohol film and a polyvinyl alcohol film copolymerized with polyethylene.

The following physical properties were evaluated about the polarizer and polarizing plate which were manufactured by the Example and the comparative example.

(1) Reflectance: A specimen was prepared by laminating the polarizing plates of Examples and Comparative Examples on an organic light emitting device panel, and then using a spectrophotometer (Spectrophotometer, Konica Minolta, CM-3600A) in SCE reflection mode (light source: D65 light source, light source aperture: Φ8 mm). , The measurement viewing angle: 10 °) to obtain the lowest value of the reflectance measured in the range of 360 nm to 740 nm.

(2) Polarization degree: The polarization degree was measured using JASCO V7100 about the polarizing plate of an Example and a comparative example at wavelength 380-780 nm.

(3) Light transmittance: The light transmittance was measured using JASCO V7100 about the polarizing plate of an Example and a comparative example at wavelength 380-780 nm.

(4) Color value bc value: About the polarizing plate of an Example and a comparative example, the color value bc value was measured using JASCO company V7100 at wavelength 380-780 nm. A reference polarizing plate having a polarization degree of 98% or more was mounted in V7100, and the color value bc value was measured by injecting the absorbing axis of the polarizer of the sample polarizing plate and the absorbing axis of the polarizer of the reference polarizing plate to be 90 ° to each other.

 (5) Crystallinity: The crystallinity of the polarizers of Examples and Comparative Examples was measured by XRD diffraction.

(6) Durability: The polarization degree (P ₁ ) was measured about the polarizing plates of an Example and a comparative example at wavelength 380-780 nm using JASCO V7100. After the polarizing plate was allowed to stand at 65 ° C./95% RH (relative humidity) for 500 hours, the degree of polarization P ₂ was measured in the same manner. Durability was evaluated according to the above formula 2.

reflectivity
(%) Polarization degree
(%) Light transmittance
(%) Color value
bc value Crystallinity
(%) durability
(%) Example 1 0.38  99.2 45 -10.25 49 2.98 Example 2 0.42 98.9 45 -8.62 41 3.49 Comparative Example 1 0.43  98.4 45 -12.65 40 6.34 Comparative Example 2 Not measurable Not measurable Not measurable Not measurable Not measurable Not measurable

As shown in Table 2, the polarizing plate of the present invention has a low reflectance, a low color value bc value, high light transmittance and polarization degree, and high durability. In particular, the polarizing plate of the present invention had low reflectance, low color value bc value, high light transmittance and high polarization degree, and high durability even when the liquid crystal layer was included on the other side of the polarizer.

On the other hand, Comparative Example 1 prepared using the conventional polyvinyl alcohol film did not have good reflectance, durability, and the like. In Comparative Example 2 prepared in the same manner as in Example 1 with a polyvinyl alcohol film, the film surface melted when stretched at 65 ° C., so that a polarizer and a polarizing plate could not be produced.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (9)

A polarizer including a polarizer, a first protective layer laminated on one surface of the polarizer, and a second protective layer laminated on the other surface of the polarizer,
The polarizer includes a polyvinyl alcohol copolymerized with only polyolefin,
The polarizing plate has a reflectance of 0.35% to 0.45%, a bc value of -8 to -12, a polarization degree of 98.5% to 99.5%, a light transmittance of 44.5% to 45.5%,
The second protective layer is a first retardation film and the second retardation film is laminated in sequence from the polarizer, the first retardation film and the second retardation film are each a liquid crystal layer,
The polarizing plate is a polarizing plate, the polarization degree change rate of the following formula 2 is 5% or less:
<Equation 2>
Change rate of polarization degree = ｜ P ₂ -P ₁ ｜
(In Formula 2, P ₁ is the initial polarization degree (unit:%) of the polarizing plate,
P ₂ is the degree of polarization (unit:%) after the polarizing plate is left for 500 hours at 65 ° C. and 95% relative humidity.
The polarizing plate of claim 1, wherein the polyvinyl alcohol copolymerized only with the polyolefin has a weight average molecular weight of 90,000 to 150,000.
According to claim 1, wherein the film containing only polyolefin copolymerized polyvinyl alcohol is a polarizing plate that Re of the following formula 1 is 1nm to 35nm at a wavelength of 550nm;
<Equation 1>
Re = (nx-ny) × d
(In Formula 1, nx and ny are refractive indexes in the x-axis and y-axis directions of the film at a wavelength of 550 nm, respectively, and d is the thickness (unit: nm) of the film).
The polarizing plate according to claim 1, wherein the polyvinyl alcohol copolymerized with only the polyolefin has a softening point of 60 ° C to 70 ° C.
The polarizing plate of claim 1, wherein the polyolefin is polyethylene.
The polarizing plate of claim 1, wherein the polarizer has a crystallinity of 40% or more.
The polarizing plate of claim 1, wherein the first retardation film has Re of the following formula 1 at a wavelength of 550 nm of 225 nm to 350 nm, and the second retardation film has a Re of the following formula 1 at a wavelength of 550 nm of 100 nm to 220 nm.
<Equation 1>
Re = (nx-ny) × d
(In Formula 1, nx and ny are refractive indexes in the x-axis and y-axis directions of the film at a wavelength of 550 nm, respectively, and d is the thickness (unit: nm) of the film).
delete A light emitting display device comprising the polarizing plate of any one of claims 1 to 7.

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