KR20130072048A - Polarizer plate and optical display device comprising the same - Google Patents

Abstract

PURPOSE: A polarizing plate which resolves white light wavelength shift phenomenon by change of side angle and has thin thickness is provided. CONSTITUTION: A polarizing plate comprises a polarizer (1); a protection film (2a) laminated on one side of the polarizer; an adhesive layer (6) laminated on the other side of the polarizer. A phase difference film (3) is formed on the polarizer, a dye-included liquid crystal layer (4) is formed on the adhesive layer, and a surface processing layer (5) can be additionally laminated on the protection film.

Description

Polarizer plate and optical display device comprising the same

The present invention relates to a polarizing plate and an optical display device including the same. More specifically, the present invention provides a polarizing plate having a side color correction effect and a front colorless effect and an optical display device including the same.

An organic light emitting diode (OLED) display device is a self-emission type display device that electrically excites a fluorescent organic compound to emit light. Such a display device can be driven at a low voltage and has advantages such as thinness. In addition, the liquid crystal display device has attracted attention recently because it can solve the drawbacks pointed out as a problem in a liquid crystal display device such as a wide viewing angle and a fast response speed.

In general, an organic light emitting diode display device includes a glass substrate, an organic light emitting unit formed on the glass substrate, a protective cap surrounding and protecting the organic light emitting unit, a moisture absorbent installed on the protective cap, and one surface of the glass substrate. It includes a polarizing plate. The polarizer is attached to the surface of the glass substrate to reduce the reflection of the glass by external light.

In an organic light emitting diode (OLED) display device, a white angular dependency (WAD) phenomenon due to a change in side angle may be a problem. WAD is a phenomenon in which white color is expressed on the front side but blue color is emitted on the side when light is emitted from the organic light emitting part of the OLED. This is because the wavelength is changed by the change in the interference length due to the resonance structure when the organic light emitting unit emits light.

To date, in order to solve the white light wavelength shift phenomenon due to the change in the side angle of the OLED, various attempts have been made such as polarizer, phase difference type 2, band cut method, and biaxial stretching phase difference compensation. However, according to this, the effect of solving the white light wavelength shift phenomenon due to the change in the side angle was weak, and there was a problem in that the thickness of the polarizing plate became thick.

An object of the present invention is to provide a polarizing plate capable of solving the white light wavelength shift phenomenon caused by the change in side angle.

Another object of the present invention is to provide a polarizing plate having a thin thickness while eliminating the white light wavelength shift phenomenon caused by the side angle change.

Still another object of the present invention is to provide an optical display device including the polarizing plate.

Polarizing plate which is an aspect of the present invention includes a polarizer, a protective film laminated on one side of the polarizer, and an adhesive layer laminated on the other side of the polarizer, may comprise a dye-containing liquid crystal layer between the polarizer and the pressure-sensitive adhesive layer. have.

In one embodiment, it may further include a retardation film between the polarizer and the pressure-sensitive adhesive layer.

In one embodiment, a protective film and a retardation film may be further included between the polarizer and the pressure-sensitive adhesive layer.

In one embodiment, the dye-containing liquid crystal layer may comprise a cured product of a mixture of the dye and the liquid crystal.

In one embodiment, the dye has an absorption wavelength It may have a 380nm-780nm.

In one embodiment, the dye is methine, azo, acridine, anthraquinone, diarylmethane, quinoline, azomethine, oxadine, styryl, coumarin, porphyrin, dibenzofuranone Or mixtures thereof.

An optical display device which is another aspect of the present invention may include the polarizing plate.

The present invention provides a polarizing plate capable of eliminating the white light wavelength shift phenomenon caused by the side angle change. The present invention provides a polarizing plate having a thin thickness as one type of retardation film while eliminating the white light wavelength shift phenomenon caused by the change in side angle. The present invention provides an optical display device including the polarizing plate.

1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention.
Figure 2 shows a cross-sectional view of a polarizing plate of another embodiment of the present invention.
Figure 3 shows a cross-sectional view of a polarizing plate of another embodiment of the present invention.
1: polarizer, 2a, 2b: protective film, 3: retardation film, 4: liquid crystal layer including dye,
5: surface treatment layer, 6: adhesive layer

Polarizing plate which is an aspect of the present invention includes a polarizer, a protective film laminated on one side of the polarizer, and an adhesive layer laminated on the other side of the polarizer, may comprise a dye-containing liquid crystal layer between the polarizer and the pressure-sensitive adhesive layer. have.

The dye-containing liquid crystal layer contains a cured product of a mixture of a dye and a liquid crystal.

The dye is a dye having a yellow-based absorption wavelength, for example, a dye having an absorption wavelength of 380-780 nm, preferably 400-600 nm, more preferably 435-480 nm.

Specifically, the dyes are methine, azo, acridine, anthraquinone, diarylmethane, quinoline, azomethine, oxadine, styryl, coumarin, porphyrin, dibenzofuranone and these It may be selected from a mixture of but is not limited thereto.

The liquid crystal may be a UV cured reactive liquid crystal. The UV curable reactive liquid crystal contains a reaction site in the molecule which can cause a curing reaction upon UV irradiation, for example by 500mJ / m2-2000mJ / m2 irradiation. Therefore, a dye-containing liquid crystal layer can be formed by performing a curing reaction with a dye by UV irradiation. In addition, the UV curable reactive liquid crystal is oriented in a C-plate shape by UV irradiation, for example by 500mJ / m2-2000mJ / m2 irradiation. As the liquid crystal is oriented in the C-plate shape, the dye is also oriented in the same direction as the liquid crystal, so that the side color correction effect can be obtained.

The liquid crystal can be purchased and used commercially available. For example, MERCK's RMS03-015 may be used, but is not limited thereto.

Although the content ratio of the dye and the liquid crystal in the dye-containing liquid crystal layer is not particularly limited, the liquid crystal: dye may be included in a weight ratio of 0.5: 1 to 20: 1. In the above range, sufficient side color correction effect and front colorless effect can be obtained when laminated on the polarizing plate. Preferably it may be included in the weight ratio of 1: 1 to 5: 1, more preferably 2: 1 to 3: 1.

In the state before hardening the mixture of dye and liquid crystal, dye and liquid crystal are orientated in arbitrary directions or shapes. As a result, the dye does not sufficiently express the absorption wavelength of the yellow series when light is transmitted in the lateral direction of the polarizing plate, and thus the side color correction effect may not be exhibited with respect to the blue wavelength expressed on the side of the polarizing plate. However, after curing the mixture of the dye and the liquid crystal, the liquid crystal is oriented in a C-plate shape, and the dye is also oriented in the same direction as the liquid crystal direction depending on the alignment of the liquid crystal.

As a result, it has the effect of color correcting the blue wavelength expressed in the lateral direction of the polarizing plate (side color correcting effect) by expressing a yellow wavelength when transmitting light in the lateral direction of the polarizing plate. On the other hand, when light is transmitted in the front direction of the polarizing plate, since the dye is oriented in the same direction as the liquid crystal direction, it may have an effect that no color is expressed in the front (front colorless effect).

As used herein, "side" or "side angle" may refer to a range of -80 degrees to 80 degrees, preferably 10 degrees to 80 degrees, or -80 degrees to -10 degrees, based on a line perpendicular to the thickness direction of the polarizing plate. have.

The dye-containing liquid crystal layer may be prepared by UV curing a mixture of the dye and the liquid crystal under normal conditions. For example, a dye and a liquid crystal are mixed. In addition, methyl ethyl ketone, xylene or a mixture thereof may be included as a solvent. A mixture comprising a dye, a liquid crystal and optionally a solvent is prepared. The mixture is coated on a retardation film, polarizer or protective film. The solvent-containing liquid crystal layer can be prepared by evaporating the solvent and curing by irradiation with UV light. The UV irradiation conditions are not limited, but can be performed under the conditions of 500 mJ / m2-2000 mJ / m2 and 30 seconds to 10 minutes.

The dye-containing liquid crystal layer may have a thickness of 500 nm or less. Within this range, sufficient side color correction effect can be obtained when included in the polarizing plate. Preferably the thickness may be 100nm to 500nm, more preferably 100nm to 400nm.

The polarizing plate of the present invention includes a polarizer, a protective film laminated on one side of the polarizer, and an adhesive layer laminated on the other side of the polarizer, and may include a dye-containing liquid crystal layer between the polarizer and the adhesive layer.

The polarizing plate may further include a retardation film between the polarizer and the pressure-sensitive adhesive layer.

1 shows a polarizing plate according to an embodiment of the present invention. According to FIG. 1, the polarizer includes a polarizer 1, a protective film 2a laminated on one surface of the polarizer, and an adhesive layer 6 laminated on the other surface of the polarizer. The retardation film 3 is formed on the polarizer, and the dye-containing liquid crystal layer 4 is formed on the pressure-sensitive adhesive layer. The protective film 5 may be further laminated with a surface treatment layer 5, for example, an antireflection layer, an antiglare layer, an antiglare and antireflection composite layer, a hard coating layer, and the like.

2 shows a polarizing plate according to another embodiment of the present invention. According to FIG. 2, the polarizer includes a polarizer 1, a protective film 2a laminated on one surface of the polarizer, and an adhesive layer 6 laminated on the other surface of the polarizer. The dye-containing liquid crystal layer 4 is formed on the polarizer, and the retardation film 3 is formed on the pressure-sensitive adhesive layer. The protective film 5 may be further laminated with a surface treatment layer 5, for example, an antireflection layer, an antiglare layer, an antiglare and antireflection composite layer, a hard coating layer, and the like.

The polarizing plate of the present invention may further include a protective film and a retardation film between the polarizer and the dye-containing liquid crystal layer.

Figure 3 shows a polarizing plate according to another embodiment of the present invention. According to FIG. 3, the first protective film 2a is laminated on one surface of the polarizer 1, the second protective film 2b is laminated on the other surface of the polarizer, and the retardation film 3 is disposed on the second protective film. The dye-containing liquid crystal layer 4 may be stacked on the retardation film, and the pressure-sensitive adhesive layer 6 may be laminated on the dye-containing liquid crystal layer. The protective film 2a may further include a surface treatment layer 5, for example, an antireflection layer, an antiglare layer, an antiglare and antireflection composite layer, a hard coating layer, and the like.

The polarizer aligns the direction of the light passing through the retardation film and divides the incident light into two polarizing components orthogonal to each other, passing only one component and absorbing or dispersing the other component.

The polarizer can be used without limitation as long as it is a polarizer conventionally used in the production of a polarizing plate. Polarizers are prepared by dyeing a polyvinyl alcohol film with iodine or a dichroic dye and stretching it in a certain direction. Specifically, it is produced through a swelling process, a dyeing step, a stretching step and a crosslinking step. Methods of performing each step are commonly known to those skilled in the art.

Although the thickness of a polarizer is not specifically limited, Preferably it may be 20 micrometers-100 micrometers.

The method of laminating the protective film on the polarizer is not particularly limited. For example, the protective film may be laminated on the polarizer through the adhesive layer. The adhesive layer may be a conventional adhesive such as an aqueous adhesive or a pressure sensitive adhesive.

The protective film may have a thickness of 20 μm-1,000 μm. In the above range, it can be used as a polarizing plate upon lamination to a polarizer. Preferably it may have a thickness of 30㎛-200㎛.

The protective film is not particularly limited, but cellulose, polyester, cyclic polyolefin, polycarbonate, polyether sulfone, polysulfone, polyamide, polyimide, polyolefin, polyarylate, polyvinyl It may be a film of a material selected from the group consisting of alcohol, polyvinyl chloride, polyvinylidene chloride or a mixture thereof. Preferably cellulose-based, more preferably triacetyl cellulose (TAC) film can be used.

The pressure-sensitive adhesive layer is an ordinary adhesive for laminating a polarizing plate on an organic light emitting diode, but acrylic or the like may be used, but is not limited thereto.

The retardation film can adjust the optical characteristics of the light to adjust the phase difference or to improve the viewing angle. The retardation film is a lambda / 4 retardation film. It serves to change the linear polarization to circular polarized light or to convert circular polarized light to linear polarized light by providing a phase difference of? / 4 to two mutually perpendicular polarization components parallel to the optical axis of the retardation film do. The retardation film changes the light resistance of the organic light emitting diode display device from circularly polarized light to linearly polarized light or changes linearly polarized light from linearly incoming light from the outside.

The retardation film may be a film having a front retardation (R ₀ ) value of 0-200 nm.

The retardation film is commonly used in a polarizing plate, and can be used without limitation as long as the film has a retardation function. As the retardation film, a film made of cycloolefin polymer (COP), acrylic, cellulose, olefin or a mixture thereof can be used. Preferably, a cycloolefin polymer film can be used.

The thickness of the retardation film may be 10 μm-100 μm. In this range, it is possible to provide an optical compensation effect when used in a polarizing plate, and can have a circular polarization effect. And preferably 10 占 퐉 to 60 占 퐉 thickness.

In the polarizing plate of the present invention, the protective film may be a surface treated protective film. Surface treatment is to impart functionality to the protective film, and may include, for example, an anti-reflective treatment, anti-glare treatment, anti-glare and anti-reflective composite treatment, hard coating treatment, and the like.

An optical display device which is another aspect of the present invention may include the polarizing plate. The optical display device may include an organic light emitting diode display device, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Specific specifications of the components used in the following examples and comparative examples are as follows.

(1) A polyvinyl alcohol film (PS60, Japan Kuraray Co., Ltd., 60 µm thick) was used as the material of the polarizer.

(2) A triacetyl cellulose film (N-TAC, Konica, Japan, 40 μm in thickness) was used as the protective film.

(3) As the retardation film, a cyclic olefin polymer film (ZEONOR, Japan ZEON Co., 33 μm in thickness) was used.

(4) As a material of the dye-containing liquid crystal layer, a dye (PF2, methine, light phosphorus, absorption wavelength = 435 to 480 nm) and a liquid crystal (RMS03-015, MERCK Co., Ltd.) were used.

Example  One

Polarizers were prepared by subjecting the material of the polarizer to a process such as dyeing and drawing. Specifically, the polyvinyl alcohol film was stretched twice at 50 ° C., adsorbed with iodine, and stretched 2.5 times in an aqueous boric acid solution at 40 ° C. to prepare a polarizer. The retardation film was adhere | attached on one surface of the polarizer using an adhesive agent. The protective film was bonded to the other side of the polarizer using an adhesive. A mixed solvent of xylene and methyl ethyl ketone was added to a mixture of 1 part by weight of the liquid crystal and 0.5 parts by weight of the dye (liquid crystal: dye ratio of 2: 1) to prepare 5 parts by weight of a mixture for forming a dye-containing liquid crystal layer. The mixture was uniformly coated on one side of the retardation film and the solvent was evaporated. UV was irradiated on 1200 mJ / m <2> and 60 second conditions, and the dye-containing liquid crystal layer (thickness: 400 nm) was laminated | stacked on the retardation film. The pressure-sensitive adhesive layer was laminated on the dye-containing liquid crystal layer to prepare a polarizing plate.

Example  2

A polarizer was prepared in the same manner as in Example 1. A protective film was attached to both sides of the polarizer using an adhesive. The retardation film was laminated | stacked using the adhesive agent to one of the protective films. A mixed solvent of xylene and methyl ethyl ketone was added to a mixture of 0.9 parts by weight of the liquid crystal and 0.3 parts by weight of the dye (liquid crystal: dye weight ratio = 3: 1) to prepare 5 parts by weight of a mixture for forming a liquid crystal layer containing dye. The mixture was uniformly coated on one side of the retardation film and the solvent was evaporated. UV was irradiated on 1200 mJ / m <2> and 60 second conditions, and the dye-containing liquid crystal layer (thickness: 400 nm) was laminated | stacked on the retardation film. The pressure-sensitive adhesive layer was laminated on the dye-containing liquid crystal layer to prepare a polarizing plate.

Example  3-4

In Example 1, except that the thickness of the dye-containing liquid crystal layer was changed as shown in Table 1, the same method was carried out to produce a polarizing plate.

Comparative example  One

Except not forming a liquid crystal layer containing a dye on the retardation film in Example 1 was carried out in the same manner to prepare a polarizing plate.

Comparative example  2

A polarizing plate was manufactured by the same method as in Example 1, except that a solution including 0.5 parts by weight of dye and 4.5 parts by weight of a mixed solvent of xylene and methyl ethyl ketone was used instead of the mixture for forming the dye-containing liquid crystal layer. It was.

Experimental Example Measurement of physical properties of polarizer

Organic light emitting diodes were assembled using the polarizing plates prepared in the above Examples and Comparative Examples, and the following properties were evaluated. The results are shown in Table 1 below.

(1) Side color correction effect: After attaching the polarizing plate to the organic light emitting diode panel, the absorption rate of the yellow wavelength band (wavelength = 435 to 480 nm) was measured at 60 degrees with an Ultraviolet-Visible Spectrophotometer. When water absorption is 10% or more ◎, When water absorption is 5% or more and less than 10% ○, (Triangle | delta) when water absorption is 1% or more and less than 5%, and it evaluated by x when water absorption is less than 1%.

(2) Front colorless effect: A polarizing plate was attached to an organic light emitting diode panel, and the absorption rate was 0% when the absorption rate at the yellow wavelength band (wavelength = 435 to 480 nm) was 0% at 0 degree angle with the ultraviolet-visible spectrophotometer 5% or less,? When the water absorption rate is more than 5% and less than 10%,? When the water absorption was 10% or more, it was evaluated as x.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Presence or absence of dye-containing liquid crystal layer ○ ○ ○ ○ × × Thickness of dye-containing liquid crystal layer (nm) 400 400 200 100 - - Dye Layer × × × × × ○ Dye layer thickness (nm) - - - - - 100 Side color correction effect ◎ ○ △ △ × ◎ Frontal colorless effect ◎ ○ △ △ ◎ ×

As shown in Table 1, the polarizing plate of the present invention has a side color compensation effect of color correction of the blue wavelength expressed at the side when light is transmitted from the side, whereas color is not expressed at the front side. On the other hand, when the dye-containing liquid crystal layer was not included, there was no side color correction effect, and the polarizing plate including only the dye layer had high side color correction effect but no front colorless effect.

Claims (15)

Polarizer,
A protective film laminated on one surface of the polarizer, and
Including an adhesive layer laminated on the other side of the polarizer,
A polarizing plate comprising a liquid crystal layer containing a dye between the polarizer and the pressure-sensitive adhesive layer. The polarizing plate according to claim 1, further comprising a retardation film between the polarizer and the pressure sensitive adhesive layer. The method of claim 2, wherein the retardation film The polarizer is laminated on the polarizer, wherein the dye-containing liquid crystal layer is laminated on the pressure-sensitive adhesive layer. The polarizing plate according to claim 2, wherein the dye-containing liquid crystal layer is laminated on the polarizer, and the retardation film is laminated on the pressure-sensitive adhesive layer. The polarizing plate of claim 1, further comprising a protective film and a retardation film between the polarizer and the pressure-sensitive adhesive layer. The polarizing plate of claim 5, wherein the protective film is laminated on one surface of the polarizer, the protective film and the retardation film are sequentially stacked on the other surface of the polarizer, and the dye-containing liquid crystal layer is laminated on the retardation film. And the pressure-sensitive adhesive layer laminated on the dye-containing liquid crystal layer. The polarizing plate of claim 1, wherein the protective film is surface treated. The polarizing plate according to claim 7, wherein the surface treatment comprises at least one selected from the group consisting of antireflection treatment, hard coating treatment, and antiglare treatment. The polarizing plate of claim 1, wherein the dye-containing liquid crystal layer has a thickness of 500 nm or less. The polarizing plate of claim 1, wherein the dye-containing liquid crystal layer is a cured product of a dye and a liquid crystal mixture. The polarizing plate of claim 10, wherein the liquid crystal is oriented in a C-plate shape upon UV irradiation. The polarizing plate according to claim 10, wherein the dye has an absorption wavelength of 380-780 nm. The method of claim 10, wherein the dye is methine, azo, acridine, anthraquinone, diarylmethane, quinoline, azomethine, oxadine, styryl, coumarin, porphyrin, dibenzofura Polarizing plate, characterized in that selected from rice fields and mixtures thereof. The polarizing plate of claim 10, wherein the liquid crystal and the dye are included in a weight ratio of liquid crystal: dye = 0.5: 1 to 20: 1. The optical display device including the polarizing plate of any one of Claims 1-14.

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