KR101943692B1 - Polarizer plate and liquid crystal display including the same - Google Patents

Polarizer plate and liquid crystal display including the same Download PDF

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Publication number
KR101943692B1
KR101943692B1 KR1020150154671A KR20150154671A KR101943692B1 KR 101943692 B1 KR101943692 B1 KR 101943692B1 KR 1020150154671 A KR1020150154671 A KR 1020150154671A KR 20150154671 A KR20150154671 A KR 20150154671A KR 101943692 B1 KR101943692 B1 KR 101943692B1
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South Korea
Prior art keywords
polarizer
protective film
liquid crystal
polarizer protective
layer
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KR1020150154671A
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Korean (ko)
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KR20170052343A (en
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유소희
심대섭
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삼성에스디아이 주식회사
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Priority to KR1020150154671A priority Critical patent/KR101943692B1/en
Priority to PCT/KR2016/011623 priority patent/WO2017078290A1/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C08L67/03—Polyesters derived from dicarboxylic acids and dihydroxy compounds the dicarboxylic acids and dihydroxy compounds having the carboxyl- and the hydroxy groups directly linked to aromatic rings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Polarising Elements (AREA)
  • Liquid Crystal (AREA)

Abstract

A polarizing plate and a liquid crystal display including the polarizing plate are provided. The polarizing plate of the present invention a polarizer and contains at least the protective film disposed on a surface, and an in-plane retardation (Re) is 0 nm to 200 nm range of the protective film, a retardation (R th) in the thickness direction of the protective film of the polarizer Is in the range of 0 nm to 1200 nm, and the amount of change in the degree of polarization of the polarizing plate is within 10% after 1000 hours of operation at a temperature of 60 DEG C and a relative humidity of 95%.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate and a liquid crystal display including the polarizing plate.

The present invention relates to a polarizing plate and a liquid crystal display including the same.

In recent years, the display field has been rapidly developed, and various flat panel display devices having excellent performance such as thinning, light weight, and low power consumption have been developed and replaced with existing CRT (cathode ray tube) .

Specific examples of such a flat panel display include a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an organic electroluminescent display Organic Electroluminescence Device).

Among them, the liquid crystal display device is one of the most widely used flat panel displays. In general, a liquid crystal display device has a structure in which a liquid crystal layer is sealed between a TFT (Thin Film Transistor) array substrate and a color filter substrate.

On the other hand, a polarizing plate composed of a polarizer and a polarizer protective film is used for the liquid crystal display device, and rainbow stains can be visually recognized due to birefringence of the polarizer protective film, which may result in poor visibility.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a polarizing plate and a liquid crystal display including the polarizing plate.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing the same.

According to another aspect of the present invention, there is provided a polarizer comprising a polarizer, and a polarizer protective film disposed on at least one side of the polarizer, wherein the polarizer protective film has an in- and, a thickness retardation (R th) is 0 nm to 1200 nm range of the polarizer protective film, the polarizing plate temperature 60 ℃, is within 10% variation in polarization degree after left standing 1000 hours at 95% relative humidity conditions.

The thickness of the polarizer protective film may range from 10 탆 to 30 탆.

The polarizer protective film may include a polyester-based material.

The polarizer protective film may be a polyethylene terephthalate type, a polyethylene naphthalate type, or a copolymer thereof.

The polarizer protective film may be a triple coextruded structure including the polyethylene terephthalate type, the polyethylene naphthalate type, or a copolymer containing the same.

The in-plane retardation (Re) of the polarizer protective film may range from 0 nm to 180 nm, and the thickness direction retardation (R th ) may range from 0 nm to 1150 nm.

The polarizer protective film may comprise an ultraviolet absorber.

And a functional layer disposed on one side of the polarizer protective film, wherein the functional layer includes at least one of a hard-coating layer, an anti-reflection layer, an anti-glare layer, And may include one or more.

The functional layer may comprise an ultraviolet absorber.

According to an aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal cell, a backlight unit, a lower polarizer disposed between the liquid crystal cell and the backlight unit, And the upper polarizer includes the polarizer.

The polarizer protective film having an in-plane retardation (Re) in the range of 0 to 200 nm and a retardation in thickness direction (R th ) in the range of 0 nm to 1200 nm may be positioned on the viewer side of the upper polarizer.

And a functional layer disposed on one side of the polarizer protective film disposed on the viewer side of the upper polarizer, wherein the functional layer comprises a hard-coating layer, an anti-reflection layer, anti-glare layer -Glare Layer) and a diffusion layer.

The details of other embodiments are included in the detailed description and drawings.

The embodiments of the present invention have at least the following effects.

That is, the polarizing plate of the present invention can be applied to a liquid crystal display device to prevent rainbow stains, thereby improving visibility.

Further, the liquid crystal display device of the present invention can prevent rainbow stain visible on the side, thereby improving the visibility.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a cross-sectional view schematically showing a polarizer according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing a polarizer according to another embodiment of the present invention.
3 and 4 are cross-sectional views schematically showing a polarizing plate according to another embodiment of the present invention.
5 is a cross-sectional view schematically showing a liquid crystal display device according to an embodiment of the present invention.
6 is a cross-sectional view schematically showing a liquid crystal cell in the liquid crystal display device of FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

It is to be understood that elements or layers are referred to as being "on " other elements or layers, including both intervening layers or other elements directly on or in between. Like reference numerals refer to like elements throughout the specification.

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

It should also be understood that the steps constituting the manufacturing method described herein may be sequential or sequential, or one step and the other step constituting one manufacturing method may be performed in the order described in the specification It is not construed as limited. Therefore, the order of the steps of the manufacturing method can be changed within a range that can be easily understood by a person skilled in the art, and a change apparent to a person skilled in the art accompanying thereto is included in the scope of the present invention.

Polarizer

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to FIG. 1 is a cross-sectional view schematically showing a polarizer according to an embodiment of the present invention.

1, a polarizer 100 according to an embodiment of the present invention includes a polarizer 110 and a polarizer protective film 120 disposed on at least one side of the polarizer 110. As shown in FIG. The in-plane retardation Re of the polarizer protective film 120 is in the range of 0 to 200 nm and the retardation R th in the thickness direction of the polarizer protective film 120 is in the range of 0 nm to 1200 nm.

The polarization plate, that is, the polarizer in which the polarizer protective film 120 is laminated to the polarizer 110, has a change in polarization degree within 10% after being left for 1000 hours under the conditions of a temperature of 60 ° C and a relative humidity of 95% . It is possible to realize excellent durability within the above range and to prevent the optical characteristics of the polarizing plate from being deteriorated even under various use conditions of the polarizing plate.

When the polarizing plate 100 is applied to a display device to be described later in the retardation range of the polarizer protective film 120, it is possible to prevent rainbow stains from occurring. More specifically, the fact that the polarizer protective film having the retardation range is located on the upper side of the display device may be more useful for preventing rainbow stains.

The in-plane retardation (Re) and thickness retardation (R th) are a polarizer protective film fast axis refractive index n y, the thickness direction of the orientation in the (120) and the refractive index of the slow axis direction in the plane of d, the thickness n x, the surface Is defined as n z , it can be defined by the following equation, respectively.

Re = (n x -n y) * d

R th = ((n x + n y) / 2-n z) * d

Also, the phase difference value may be defined as a positive value as an absolute value.

The slow axis is a direction in which the in-plane refractive index of the polarizer-protective film 120 becomes maximum, and the fast axis is defined as a direction perpendicular to the slow axis in the plane.

In general, when the fast axis of the polarizer protective film 120 is? R and the absorption axis is? P, when the? R-p value is not 90 or 0 degrees, that is, when the slow axis r of the polarizer protective film 120 And the absorption axis p of the polarizer are not perpendicular (90 °) or parallel (0 °), the rainbow stain is visually recognized by the influence of the phase difference birefringence. When the polarizer protective film of the present invention is positioned at the end of the viewing direction, the iridescence may not be visible without being influenced by the value of? R-p.

In an exemplary embodiment, for the above reasons, the in-plane retardation Re may range from 0 nm to 200 nm, from 0 nm to 180 nm, or from 0 nm to 100 nm. Further, the thickness direction retardation (R th ) may be in the range of 0 nm to 1150 nm, and may be in the range of 0 nm to 500 nm. Within this range, visibility without rainbow can be further reduced.

The polarizer 110 is a film that can convert natural light or polarized light into arbitrary polarized light, and can generally be converted into specific linearly polarized light. As the polarizer 110, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially porous polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer system partially saponified film may be produced by adsorbing a dichroic substance such as iodine or a dichroic dye, , A polyene-based oriented film such as a dehydrated product of phlyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride, and the like, but the present invention is not limited to these. In the exemplary embodiment, a polyvinyl alcohol-based film that can have a high degree of polarization and is excellent in adhesion to the polarizer-protective film 120 can be exemplified, but not limited thereto.

The polarizer protective film 120 may include a polyester-based material.

As the polyester, for example, terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5- Naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylsulfone carboxylic acid, anthracene dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,3-cyclo Hexane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethyl malonic acid, succinic acid, 3,3-diethyl succinic acid, glutaric acid, 2,2 - dicarboxylic acids such as dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid and dodecadicarboxylic acid, Ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexane (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) propane, -Hydroxyphenyl) sulfone, and the like, but the present invention is not limited thereto. A homopolymer obtained by polycondensing one kind of each of the above materials or a copolymer obtained by polycondensing at least one kind of dicarboxylic acid and two or more kinds of diols or a copolymer obtained by polycondensing two or more kinds of dicarboxylic acids and one or more kinds of diols And a blend resin obtained by blending two or more of these homopolymers or copolymers.

In an exemplary embodiment, an aromatic polyester may be used from the viewpoint that the polyester exhibits crystallinity, and examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and copolymers thereof However, the present invention is not limited to these.

In addition, the polarizer protective film 120 may be a triple coextruded structure including a polyethylene terephthalate type, a polyethylene naphthalate type, or a copolymer resin containing them.

The polyester film is obtained by, for example, a method of melt-extruding the above-mentioned polyester resin into a film form and then cooling and solidifying it by a casting drum to form a film. In the present invention, a stretched polyester film, in particular, a biaxially stretched polyester film can be suitably used from the viewpoint of imparting crystallinity to the polyester film and achieving the above properties. In the case of using as the first protective film an aromatic polyester as a main component, such a film may contain a resin other than an aromatic polyester, an additive, or the like.

When the polarizer protective film 120 is a stretched film, the stretching method is not particularly limited, and a longitudinal uniaxial stretching method, a transverse monoaxial stretching method, a longitudinal and transverse biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method may be employed. In the exemplary embodiment, the simultaneous biaxial stretching method may be used, but the present invention is not limited thereto. As the stretching means, any appropriate stretching machine such as a roll stretching machine, a tenter stretching machine, or a pantograph or linear motor type biaxial stretching machine can be used.

On the other hand, the thickness of the polarizer protective film 120 may be in the range of 10 탆 to 30 탆 for thinning. However, the present invention is not limited to this.

The polarizer protective film 120 may comprise an ultraviolet absorber. The transmittance of light having a wavelength of 380 nm of the polarizer protective film 120 can be controlled within a range of 1% to 55% by the ultraviolet absorber.

The first adhesive layer 10 is interposed between the polarizer 110 and the polarizer protective film 120 so that the polarizer 110 and the polarizer protective film 120 may be bonded to each other. The first adhesive layer 10 may include an aqueous adhesive, but not limited thereto, and may include an ultraviolet curable adhesive.

The water-based adhesive may include at least one selected from the group consisting of a polyvinyl alcohol-based resin and a vinyl acetate-based resin, or may include a polyvinyl alcohol-based resin having a hydroxyl group, but is not limited thereto.

The ultraviolet curable adhesive may include an acrylic compound, for example, acrylic, urethane-acrylic, or epoxy. However, the present invention is not limited thereto.

2 is a cross-sectional view of a polarizer according to another embodiment of the present invention. Referring to FIG. 2, the polarizer 101 includes a functional layer 150 disposed on one side of the polarizer- . The functional layer 150 may include at least one of a hard-coating layer, an anti-reflection layer, an anti-glare layer, and a diffusion layer.

More specifically, the functional layer 150 may be formed on one surface of the polarizer protective film 120, that is, on the surface opposite to the surface on which the polarizer 110 of the polarizer protective film 120 is disposed. For example, the hard coating layer improves wet heat durability of the polarizing plate and prevents dimensional change. The anti-reflection layer dissolves light emitted from the outside and reflects the light. And the anti-glare layer can prevent the glare by inducing diffusion and reflection of light incident from the outside.

Meanwhile, the functional layer 150 may include an ultraviolet absorber. As a result, the transmittance of light having a wavelength of 380 nm in the light passing through the functional layer 150 can be controlled within a range of 1% to 55%.

The other structures are the same as those described above, and overlapping descriptions will be omitted.

3 is a cross-sectional view of a polarizer according to another embodiment of the present invention. 3, a polarizer protective film 120 may be disposed in a state that the first adhesive layer 10 is interposed on one surface of the polarizer 110. The polarizer 110 may include a primer The layer 30 and the adhesive layer 130 may be disposed. Also, a separate film is not shown, and a release film is disposed on the outer surface of the adhesive layer 130, so that the polarizing plate can be easily stored and transported. The adhesive layer 130 may be used to attach a polarizing plate to a display panel to be described later. In addition, the primer layer 30 protects the polarizer 110 and improves adhesion between the polarizing plate 102 and a display panel to be described later. The primer layer 30 may be formed by applying a coating solution containing a water-dispersible polymer resin, water-dispersible fine particles, and water on a polarizer 110 using a bar coating method, a gravure coating method, and the like, followed by drying .

The other structures are the same as those described above, and overlapping descriptions will be omitted.

4 is a cross-sectional view of a polarizer according to another embodiment of the present invention. 4, the polarizing plate 103 includes polarizer protective films 120 and 140 laminated on both sides of the polarizer 110 with a first adhesive layer 10 and a second adhesive layer 20 interposed therebetween. . In addition, although not separately shown, an adhesive layer may be formed on one side of the polarizer protective film 120, 140 and attached to the display panel.

The other structures are the same as those described above, and overlapping descriptions will be omitted.

Liquid crystal display

FIG. 5 is a cross-sectional view schematically showing a liquid crystal display device according to an embodiment of the present invention, and FIG. 6 is a schematic cross-sectional view of a liquid crystal cell included in the liquid crystal display device of FIG.

5 and 6, the liquid crystal display 1 includes a liquid crystal cell 200, a backlight unit 500, a lower polarizer plate 400 disposed between the liquid crystal cell 200 and the backlight unit 500, And an upper polarizer 300 disposed on the viewing side of the cell 200. The upper polarizer 300 disposed on the viewer side includes the polarizer described above.

That is, the upper polarizer 300 may include a polarizer protective film having an in-plane retardation Re in the range of 0 to 200 nm and a retardation in the thickness direction R th in the range of 0 nm to 1200 nm. More specifically, The polarizer protective film satisfying the retardation range may be positioned on the viewer side of the upper polarizer, thereby preventing the occurrence of the iridescence phenomenon.

The upper polarizer 300 may further include a functional layer disposed on one side of the polarizer protective film disposed on the viewer side of the upper polarizer 300. The functional layer may include a hard coating layer, An anti-reflection layer, an anti-glare layer, and a diffusion layer. These functional layers have already been described above, and overlapping descriptions will be omitted.

6, the liquid crystal cell 200 includes a first substrate 210, a second substrate 230, a liquid crystal layer 220 sealed between the first substrate 210 and the second substrate 230 And the upper polarizer 300 may be laminated on one surface (upper surface) of the first substrate 210.

The lower polarizer 400 may be laminated on the lower surface of the second substrate 230. When the two polarizers 300 and 400 are positioned above and below the liquid crystal cell 200, Orthogonal or parallel. In this case, the protective film having the above-described specific retardation may be formed on the lower surface of the lower polarizer 400, that is, on the side of the backlight unit 400 As shown in FIG.

The first substrate 210 may be a color filter (CF) substrate. Although not shown in the figure, for example, a black matrix for preventing light leakage and a color filter of red, green, and blue and a transparent conductive material such as ITO or IZO are formed on a lower surface of a substrate made of a transparent insulating material such as glass or plastic And a common electrode which is an electric field generating electrode formed of an oxide.

The second substrate 230 may be a TFT (Thin Film Transistor) substrate. Though not specifically shown in the drawing, for example, a thin film transistor composed of a gate electrode, a gate insulating film, a semiconductor layer, a resistive contact layer, and a source / drain electrode and a thin film transistor formed of ITO or ITO are formed on a substrate made of a transparent insulating material such as glass or plastic. And a pixel electrode that is an electric field generating electrode formed of a transparent conductive oxide such as IZO.

The plastic substrate that can be used for the first substrate 210 and the second substrate 230 may be a plastic substrate such as PET (polyethylene terephthalate), PC (polycarbonate), PI (polyimide), PEN (polyethylene naphthalate) sulfone, PAR (polyarylate), and COC (cycloolefin copolymer). However, the present invention is not limited thereto. Also, the first substrate 210 and the second substrate 230 may be made of a flexible material.

The liquid crystal layer 220 may be a twisted nematic (TN) mode having a positive dielectric constant anisotropy, a vertically aligned (VA) mode or a horizontally aligned (IPS, FFS) mode or the like. In Fig. 6, the TN mode is described as an example.

When no electric field is applied to the liquid crystal layer 220 due to the absence of a voltage difference between the pixel electrode and the common electrode, that is, the electric field generating electrode, the liquid crystal of the liquid crystal layer 220, as shown in FIG. 6, And is arranged parallel to the surfaces of the substrate 210 and the second substrate 230 and has a structure in which the first substrate 210 and the second substrate 230 are spirally twisted by 90 °.

The polarized light of linearly polarized light passes through the liquid crystal layer 220 and changes due to retardation due to the refractive index anisotropy of the liquid crystal. When the dielectric anisotropy (DELTA epsilon) of the liquid crystal and the chiral pitch or the thickness of the liquid crystal layer 220, i.e., the cell gap, are adjusted, the linearly polarized light direction of the light passing through the liquid crystal layer 220 is 90 °.

The backlight unit 500 may generally include a light source, a light guide plate, a reflective film, and the like. Depending on the configuration of the backlight, it can be arbitrarily divided into a direct-down system, a sidelight system, and a planar light source system.

Although not shown separately, the liquid crystal display device 1 may include an optical film or an optical sheet disposed between the lower polarizer plate 400 and the backlight unit 500. The optical film or the optical sheet may include one or more brightness enhancement films, a diffusion sheet, a prism sheet, and the like, which are well known in the art and will not be described in detail.

Method for producing polarizer

Although not shown separately, the polarizing plate manufacturing method may include a step of preparing a polarizer protective film and a polarizer, and a step of laminating the polarizer protective film and the polarizer through an adhesive.

The step of preparing the polarizer may include a dyeing step of dyeing a polyvinyl alcohol film with iodine or a dichroic dye and a stretching step of stretching the polyvinyl alcohol film.

The step of saponification may be performed by impregnating a polyvinyl alcohol-based film with a solution of iodine or a dichroic substance. For example, the temperature of the iodine solution may be in the range of 20 ° C to 50 ° C, and the duration of the iodine solution may be in the range of 10 to 300 seconds. When an iodine solution is used as the iodine solution, an aqueous solution containing iodine (I 2 ) and iodide ions, for example, potassium iodide (KI) used as a solubilizing agent may be used.

Meanwhile, in the step of solidifying, the step of swelling the polyvinyl alcohol-based film in a swelling bath may be further included. In addition, the swelling step may be carried out in a temperature range of 40 ° C to 80 ° C, for example, in a range of 50 ° C to 75 ° C or 60 ° C to 70 ° C. The swelling step softens the molecular chain of the polyvinyl alcohol-based film and loosens the molecular chain, thereby allowing the dichroic substance to be dyed into the polyvinyl alcohol-based film during the dyeing process. In this case, By increasing the swelling temperature to the vicinity of the glass transition temperature of the alcohol-based film, the crystal content in the polyvinyl alcohol-based film can be reduced and the movement of the molecules can be made active to increase the swelling rate. As a result, the dyeability of the dichroic substance is increased, and the dichroic substance is homogeneously dyed on the polyvinyl alcohol-based film, so that it can have high optical properties and excellent orthogonal transmittance upon stretching.

The swelling rate may be from 130% to 270%. In this swelling process, the polyvinyl alcohol film can be stretched. When the swelling rate and the elongation are satisfied, high transparency can be achieved while preventing physical property of the polarizing film from being stained during the dyeing process, improving optical property uniformity, and so on. The swelling step may be performed by a dry method or a wet method. In an exemplary embodiment, it may be carried out in a wet process in a swelling tank containing a swelling liquid.

In another exemplary embodiment, a crosslinking process may be further included after the solidifying step.

When the molecules of iodine or the dichroic substance are dyed in the polyvinyl alcohol film in the step of saponification, the dichroic molecules are adsorbed onto the polymer matrix of the polyvinyl alcohol-based film by using boric acid, borate or the like. Examples of the crosslinking method include a deposition method in which a polyvinyl alcohol-based film is immersed in an aqueous solution of boric acid or the like, but the present invention is not limited thereto. The crosslinking method may be carried out by a coating method or a spraying method, It is possible.

On the other hand, in the stretching step, the polyvinyl alcohol-based film can be stretched by a wet stretching method and / or a dry stretching method common in the art. The final stretching ratio of the polyvinyl alcohol-based film may be in the range of 5.0: 1 or more, for example, in the range of 5.5: 1 or more, or 6.0: 1 or more.

Examples of the dry stretching method include inter-roll stretching method, heating roll stretching method, compression stretching method, tenter stretching method, and the like, and the wet stretching method Non-limiting examples include a tenter stretching method and a roll-to-roll stretching method.

In the case of the above wet stretching method, stretching can be performed in an alcohol, water, or boric acid aqueous solution. For example, a solvent such as methyl alcohol or propyl alcohol may be used, but not limited thereto.

The stretching temperature and time may be appropriately selected depending on the material of the film, the desired elongation, the method of use, and the like. The stretching step may be uniaxial stretching or biaxial stretching. However, in order to produce a polarizing film to be attached to a liquid crystal cell of a liquid crystal display device to be described later, biaxial stretching can be carried out so as to realize a retardation property.

On the other hand, the steps such as dyeing, stretching, crosslinking, swelling and the like may be performed in a state in which the polyvinyl alcohol-based film and the base film are laminated.

The step of preparing the polarizer protective film may include a step of producing a non-stretched polyester film and a step of stretching the non-stretched polyester film.

The step of producing an unstretched polyester film is not particularly limited, but a melt extrusion method can be used, for example. It is possible to melt at a melting temperature of the polyester-based material or higher and discharge it out of the extrusion facility to form a non-stretched film. Hereinafter, the melt extrusion method will be described in more detail.

If the content of water present in the raw material in the melt extrusion process is above a certain level, bubble-like product defects such as orange peel may occur. Therefore, the moisture content should be controlled to a certain level or less. The shape of the dryer is not particularly limited, and examples thereof include a dehumidifying dryer, a hot air dryer, and the like, but are not limited thereto. The drying temperature can be performed below the glass transition temperature of the film raw material. However, it goes without saying that the drying temperature can be appropriately selected depending on the kind of resin used and the glass transition temperature. If the drying temperature is too low, there is no drying effect. On the contrary, if the drying temperature is higher than necessary, the characteristics of the raw material are changed and it is not appropriate. The drying time of the raw material may be in the range of 0.5 to 5 hours, but can be easily selected in consideration of the ambient humidity and the like.

The dried raw material can be supplied to the raw material storage (hopper) located at the entrance of the extrusion facility. In some cases, the filter may be routed through the filter while primarily circulating air in the reservoir to remove impurities that may be contained in the feed.

The input material is filled in the first section of the screw inside the extrusion facility. The first section serves to transfer the raw material to the extruding equipment cylinder.

Hereinafter, the second section is a section in which melting of the raw material starts, and is preferably set to a temperature higher than the glass transition temperature of the film raw material.

The third section serves to completely convert the raw material into the melt. The temperature setting can be maintained in the same range as the second section.

The fourth section increases the density of the molten material by increasing the pressure of the molten raw material, thereby securing a stable discharge amount. In this process, the temperature condition can be maintained in the same range as the second and third intervals so that the discharged melt is not cured.

In some cases, it passes through a gear pump section that transfers the melt to the tee die by a certain amount. When the raw material is fed directly to the tie die through the screw in the cylinder of the extrusion equipment, the quantity of the raw material to be transferred is irregular, so that a product of excellent quality can not be obtained. Therefore, the gear pump can store irregularly charged raw materials from the extruding equipment cylinder in a certain space, and can steadily supply a certain amount of molten material to the tie die, thereby minimizing a change in the pressure distribution.

The section through which the melt is finally discharged out of the extrusion facility is a tee section. The shape of the film and the production thickness are determined according to the shape of the Ti-die. The shape of the tee die can be classified into a "T" die, a coat hanger die, a fish tail die, and the like, but is not limited thereto. The type of tie dies can be selectively used depending on the flowability of the melt.

The step of stretching the non-stretched polyester film may use a general wet stretching method and / or dry stretching method in the art.

Examples of the dry stretching method include inter-roll stretching method, heating roll stretching method, compression stretching method, tenter stretching method, and the like, and the wet stretching method Non-limiting examples include a tenter stretching method and a roll-to-roll stretching method.

In the case of the above wet stretching method, stretching can be performed in an alcohol, water, or boric acid aqueous solution. For example, a solvent such as methyl alcohol or propyl alcohol may be used, but not limited thereto.

Further, the stretching may be performed by a vertical uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse biaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, or the like.

In the exemplary embodiment, the biaxial stretching method can be used to have the above retardation value, and for the same reason, the simultaneous biaxial stretching method can be used, but the present invention is not limited thereto.

The stretching ratio (MD: TD) of the stretching step may vary depending on a desired thickness range and the like, and is not particularly limited. For example, (2.0: 1.0-3.0) to (3.5: 2.0-4.5). That is, the TD direction elongation can be set within the range of ± 1.0 times to ± 1.5 times the MD direction elongation. In this case, the elongation in the MD direction may range from 2.0 to 4.5 times.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Hereinafter, the polarizing plate and the liquid crystal display of the present invention will be described in more detail with reference to Production Examples and Experimental Examples.

Production Examples 1 to 10 and Comparative Examples 1 to 5

The thickness, the in-plane retardation (Re) and the thickness direction retardation (Rth) of the polyethylene terephthalate were respectively measured by the melt-extrusion process and the simultaneous biaxial stretching method using the values shown in Table 1 below, Vinyl alcohol polarizer to prepare a polarizing plate.

The in-plane retardation Re and the thickness direction retardation Rth can be defined by the following equations (1) and (2), and the phase difference value can be defined as an absolute value and a positive number.

Re = (n x -n y) × d formula (1)

R = th ((n + x n y) / 2 n-z) * d formula (2)

Where n x is the refractive index in the slow axis direction in the film plane, n y is the refractive index in the fast axis direction in the film plane, n z is the refractive index in the thickness direction, and d is the thickness of the polarizing plate. Further, the slow axis may be defined as a direction in which the in-plane refractive index of the protective film becomes maximum, and the fast axis may be defined as a direction perpendicular to the slow axis in the plane.

On the other hand, the in-plane retardation Re and the thickness direction retardation (Rth) were measured at a measurement wavelength of 550 nm under an environment of 23 캜 by using a product name AxoScan made by Axometrics, a phase difference measurement system. The order of the measured values of the retardation was determined so as to coincide with the wavelength dispersion of the retardation of the previously obtained polyester film.

Experimental Example 1

The polarizing plates prepared in Production Examples 1 to 10 and Comparative Examples 1 to 5 were applied to the visible side of the liquid crystal cell to test whether or not rainbow stains were visually observed.

Thickness [탆] Re [nm] R th [nm] A rainbow stain poet Production Example 1 30 150 850 Level 0 Production Example 2 30 90 1200 Level 1 Production Example 3 30 180 1150 Level 0 Production Example 4 20 100 1050 Level 0 Production Example 5 20 120 1150 Level 0 Production Example 6 20 70 760 Level 0 Production Example 7 20 50 820 Level 0 Production Example 8 10 50 500 Level 0 Production Example 9 10 130 750 Level 0 Production Example 10 10 150 1100 Level 0 Comparative Example 1 40 150 5300 Level 2 Comparative Example 2 40 200 5500 Level 2 Comparative Example 3 38 4100 6500 Level 2 Comparative Example 4 30 150 4300 Level 2 Comparative Example 5 20 243 1689 Level 2

Level 0: Rainbow Stain Missy Inn

Level 1: Rainbow spots are not visible, but a single color vision. Applicable level

Level 2: Rainbow Stain Poison "Medium" or above, not applicable level

Referring to Table 1, in the case of the liquid crystal cell to which the polarizer protective film satisfying the retardation range of the present invention is applied, iridescence is not observed, whereas in the comparative example, iridescence is visible.

Therefore, when the polarizing plate of the present invention is used in a liquid crystal display device, it is possible to prevent rainbow stains and improve visibility.

Comparative Example 6

A triacetylcellulose (TAC) protective film was used as a polarizer protective film, and the TAC protective film was laminated on one side of the polarizer to prepare a polarizing plate.

Experimental Example 2

A hard coat layer (HC) was formed outside the polarizer protective films of Production Examples 1 and 2 and Comparative Example 6, and no separate layer was formed on the polarizer protective film of Production Example 3. [ The polarizing plates of Production Examples 1 and 2 and Comparative Example 6 in which the hard coating layer was formed and the polarizing plate of Production Example 3 in which the hard coating layer was not formed were laminated on the glass using a pressure-sensitive adhesive for reliability test of high temperature and high humidity, , And the relative humidity was 95%, the change rate of the degree of polarization after 1000 hours was measured. The polarization degree was measured using a V-7100 model (Jasco), and the results are shown in Table 2 below.

Whether surface treatment is applied to the polarizer protective film Change in polarization degree 0h After 1000h Rate of change (%) Production Example 1 Hard coating layer 99.996 99.989 One Production Example 2 Hard coating layer 99.989 99.970 2 Production Example 3 X 99.988 99.960 3 Comparative Example 6 Hard coating layer 99.996 99.881 11

As shown in Table 2, when the polarizer protective film of the present invention was used, it was confirmed that the rate of change of polarization degree could be minimized even under severe test conditions.

It will be appreciated that the embodiments described above are all exemplary and that different embodiments may be applied in combination.

1: Liquid crystal display
10: First adhesive layer
20: Second adhesive layer
100, 101, 102, 103: polarizer
110: Polarizer
120, 140: Polarizer protective film
130: adhesive layer
150: Functional layer
200: liquid crystal cell
210: a first substrate
220: liquid crystal layer
230: second substrate
300: Upper polarizer
400: lower polarizer plate
500: Backlight unit

Claims (12)

A polarizer; And
A polarizer protective film disposed on at least one surface of the polarizer,
Wherein an in-plane retardation (Re) of the polarizer protective film is in the range of 50 nm to 200 nm, a thickness direction retardation (R th ) of the polarizer protective film is in a range of 0 nm to 1200 nm,
The polarizing plate had a change amount of the polarization degree within 10% after being left for 1000 hours at a temperature of 60 DEG C and a relative humidity of 95%
Wherein the polarizer protective film comprises a polyethylene terephthalate type, a polyethylene naphthalate type, or a copolymer film comprising the same. The method according to claim 1,
Wherein the polarizer protective film has a thickness ranging from 10 탆 to 30 탆. delete delete The method according to claim 1,
Wherein the polarizer protective film is a triple coextruded structure comprising the polyethylene terephthalate-based, polyethylene naphthalate-based, or copolymer thereof. The method according to claim 1,
Wherein the in-plane retardation (Re) of the polarizer protective film is in the range of 50 nm to 180 nm, and the thickness direction retardation (R th ) is in the range of 0 nm to 1150 nm. The method according to claim 1,
Wherein the polarizer protective film comprises an ultraviolet absorber. The method according to claim 1,
Further comprising a functional layer disposed on one surface of the polarizer protective film,
Wherein the functional layer comprises at least one of a hard-coating layer, an anti-reflection layer, an anti-glare layer, and a diffusion layer. 9. The method of claim 8,
Wherein the functional layer comprises an ultraviolet absorber. A liquid crystal cell;
Backlight unit;
A lower polarizer disposed between the liquid crystal cell and the backlight unit; And
And an upper polarizer disposed on the viewing side of the liquid crystal cell,
Wherein the upper polarizer comprises the polarizer of any one of claims 1, 2 and 5 to 9. 11. The method of claim 10,
A liquid crystal display device and the in-plane retardation (Re) is 50 nm to 200 nm range of the polarizer, the polarizer protective film, the thickness retardation (R th) is 0 nm to 1200 nm range is located on the visual side of the upper polarizer. 11. The method of claim 10,
Further comprising a functional layer disposed on one surface of the polarizer protective film disposed on the viewer side of the upper polarizer,
Wherein the functional layer includes at least one of a hard-coating layer, an anti-reflection layer, an anti-glare layer, and a diffusion layer.
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KR20190097639A (en) * 2018-02-12 2019-08-21 삼성에스디아이 주식회사 Antireflection film, polarizing plate comprising the same and optical display apparatus comprising the same
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