KR102434542B1 - Polarizing plate for ips liquid crystal display apparatus and ips liquid crystal display apparatus comprising the same - Google Patents

Abstract

A polarizing plate for an IPS liquid crystal display, comprising a polarizer, a polarizer protective film formed on a light exit surface of the polarizer, and a positive C layer formed on a light incident surface of the polarizer, wherein the positive C layer is formed directly on the polarizer and an IPS liquid crystal display including the same.

Description

Polarizing plate for IPS liquid crystal display and IPS liquid crystal display including same

The present invention relates to a polarizing plate for an In Plane Switching (IPS) liquid crystal display and an IPS liquid crystal display including the same.

Liquid crystal display devices can be classified according to the type of liquid crystal used. In the IPS (in Plane Switching) liquid crystal mode, when the liquid crystal is oriented in the horizontal direction and two electrodes are driven on one substrate, the liquid crystal rotates on a plane, thereby improving the wide viewing angle by using a method of transmitting or blocking light. . Since the IPS mode controls the amount of light by horizontal movement of the liquid crystal, the viewing angle characteristics are considerably improved, so it is currently used in many products. Unlike the VA (vertical alignment) mode, the IPS mode is a method that has excellent viewing angle characteristics and color change characteristics even in a state where a retardation film is not applied.

However, if there is a pre-tilt in the alignment of the IPS liquid crystal, there is a high possibility that left and right anisotropy will occur. As a result, a color difference between left and right occurs, resulting in poor screen quality.

Background art of the present invention is disclosed in Korean Patent Application Laid-Open No. 10-2010-0085335 and the like.

It is an object of the present invention to provide a polarizing plate for an IPS liquid crystal display capable of improving screen quality by resolving a difference in left and right visual perception and/or left and right color due to pre-tilt during IPS liquid crystal alignment from the front as well as the side. .

Another object of the present invention is to provide a polarizing plate for an IPS liquid crystal display having a high degree of polarization.

Another object of the present invention is to provide a polarizing plate for an IPS liquid crystal display capable of simultaneously obtaining a thinning effect and an effect of minimizing or suppressing the occurrence of warpage.

Another object of the present invention is to provide an IPS liquid crystal display including the polarizing plate for the IPS liquid crystal display of the present invention.

The polarizing plate for an IPS liquid crystal display of the present invention includes a polarizer, a polarizer protective film formed on a light exit surface of the polarizer, and a positive C layer formed on a light incident surface of the polarizer, wherein the positive C layer is directly on the polarizer can be formed.

The IPS liquid crystal display device of the present invention may include a polarizing plate for the IPS liquid crystal display device of the present invention.

The present invention provides a polarizing plate for an IPS liquid crystal display capable of improving the screen quality by resolving the difference in left and right visual perception and/or left and right color due to pre-tilt when aligning the IPS liquid crystal from the front as well as the side.

The present invention provides a polarizing plate for an IPS liquid crystal display having a high degree of polarization.

The present invention provides a polarizing plate for an IPS liquid crystal display capable of simultaneously obtaining a thinning effect and an effect of minimizing or suppressing the occurrence of warpage.

The present invention provides an IPS liquid crystal display including the polarizing plate for the IPS liquid crystal display of the present invention.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.
2 shows color coordinates when applied to an IPS liquid crystal display in Examples 1 to 4 and Comparative Examples 1 to 2;
3 shows the application results when applied to an IPS liquid crystal display in Example 1 (FIG. 3(a)), Example 2 (FIG. 3(b)), and Comparative Example 1 (FIG. 3(c)) will be.

It will be described in detail so that a person of ordinary skill in the art can easily carry out the present invention with reference to the accompanying drawings and embodiments. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention, parts not related to the description are omitted.

In the present specification, the "in-plane retardation (Re)" is represented by the following formula A, the "thickness direction retardation (Rth)" is represented by the following formula B, and "the degree of biaxiality (NZ)" can be represented by the following formula C have:

<Formula A>

Re = (nx - ny) x d

<Formula B>

Rth = ((nx + ny)/2 - nz) x d

<Formula C>

NZ = (nx - nz)/(nx - ny)

(In Equations A to C, nx, ny, and nz are refractive indices in the slow axis direction, fast axis direction, and thickness direction of the optical element at a wavelength of 550 nm, and d is the thickness (unit: nm) of the optical element). The "optical element" may be a positive C layer, or a polarizer protective film.

The inventor of the present invention is a polarizing plate for liquid crystal display for IPS used in liquid crystal display for IPS, and by laminating only the positive C layer of the present invention on the light incident surface of the polarizer, the front surface due to pre-tilt during liquid crystal alignment in liquid crystal for IPS And it is possible to solve the problem of the difference in visual perception from the left and right side, and by forming the positive C layer directly on the light incident surface of the polarizer, the effect of thinning the polarizing plate and improving the warpage was obtained, and it was confirmed that the polarization degree of the polarizing plate was also excellent. The invention was completed.

Hereinafter, a polarizing plate for an IPS liquid crystal display (hereinafter referred to as a polarizing plate) according to an embodiment of the present invention will be described in detail with reference to FIG. 1 .

Referring to FIG. 1 , the polarizing plate may include a polarizer 100 , a polarizer protective film 200 formed on an upper surface of the polarizer 100 , and a positive C layer 300 formed on a lower surface of the polarizer 100 . . A polarizer 100 and a polarizer protective film 200 are sequentially formed from the positive C layer 300 .

The polarizer 100 may polarize and emit light emitted from the IPS liquid crystal and passing through the positive C layer. The polarizer 100 may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The polarizer 100 may have a thickness of 5 μm to 40 μm. Within the above range, it can be used for an IPS liquid crystal display.

The polarizer protective film 200 may be formed on the light emitting surface of the polarizer 100 to emit light emitted from the polarizer 100 . The polarizer protective film 200 also increases the mechanical strength of the polarizer 100, but in the present invention, when the positive C layer 300 formed on the light incident surface of the polarizer 100 is formed, the positive C layer 300 is formed. It can be formed stably. Although the polarizer is manufactured from a polyvinyl alcohol-based film, it is flexible, so it may be difficult to form the positive C layer by directly coating the composition for the positive C layer on the polarizer alone. When the composition for the positive C layer is coated on the polarizer, the polarizer protective film may serve as a support.

The polarizer protective film 200 may have a thickness of 10 μm to 80 μm, preferably 40 μm to 80 μm. When forming the positive C layer in the above range, the positive C layer can be stably formed and used for a polarizing plate. The polarizer protective film 200 may include an optically transparent protective film. The polarizer protective film includes a cellulose ester-based resin containing triacetyl cellulose (TAC), etc., a cyclic polyolefin-based resin containing amorphous cyclic polyolefin (COP), etc., a polycarbonate-based resin, polyethylene terephthalate (PET), etc. Poly(meth)acrylate including polyester-based resin, polyethersulfone-based resin, polysulfone-based resin, polyamide-based resin, polyimide-based resin, acyclic-polyolefin-based resin, polymethyl methacrylate resin, etc. It may include a film formed of at least one of a resin-based resin, a polyvinyl alcohol-based resin, a polyvinyl chloride-based resin, and a polyvinylidene chloride-based resin, but is not limited thereto.

The polarizer protective film 200 may be a protective film having a low retardation, such as a cellulose ester-based resin including triacetyl cellulose (TAC). However, the polarizer protective film 200 may provide an effect of providing high durability to the polarizing plate due to the use of a low moisture-permeable substrate by having a high retardation or an ultra-high retardation. In addition, the polarizer protective film having a high retardation or an ultra-high retardation is highly stretched in the TD or MD uniaxial direction. In particular, in the present invention, the positive C layer is directly formed on the light incident surface of the polarizer and the polarizer protective film having the high retardation or ultra-high retardation is provided on the light exit surface of the polarizer, so that the luminous difference improvement effect of the present invention is better can come out In addition, the present invention may have excellent warpage improvement effect by controlling the shrinkage stress between the polarizer stretched in the absorption axis direction and the polarizer protective film highly stretched in the uniaxial direction due to the positive C layer described in detail below. The angle between the absorption axis of the polarizer and the slow axis direction of the polarizer protective film is 0° when the absorption axis of the polarizer is 0°, and the slow axis direction of the polarizer protective film may be -5° to 5° or 0°.

In one embodiment, the polarizer protective film 200 has an in-plane retardation Re of 6,000 nm or more at a wavelength of 550 nm, for example, 6,000 nm to 12,000 nm, preferably 8,000 nm to 10,000 nm, more preferably 8,000 nm to 9,000 nm can be In the above range, when the polarizing plate is applied to the IPS liquid crystal, there may be an effect of reducing the color difference between left and right.

The polarizer protective film 200 may have a thickness direction retardation Rth of 12,000 nm or less at a wavelength of 550 nm, preferably 8,000 nm to 12,000 nm, 8,000 nm to 10,000 nm, and 9,000 nm to 10,000 nm. In the above range, when the polarizing plate is applied to the IPS liquid crystal, there may be an effect of reducing the color difference between left and right.

The polarizer protective film 200 may have a degree of biaxiality NZ of 1.7 or less at a wavelength of 550 nm, preferably 1.2 to 1.7, and 1.5 to 1.6. In the above range, when the polarizing plate is applied to the IPS liquid crystal, there may be an effect of reducing the color difference between left and right.

Although not shown in FIG. 1 , an additional function may be provided to the polarizer protective film 200 in which a functional coating layer is formed on the upper surface of the polarizer protective film 200 , that is, a surface that does not face the polarizer 100 . For example, the functional coating layer may include at least one of a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, a low reflection layer, and an anti-glare layer, but is not limited thereto.

Although not shown in FIG. 1 , an adhesive layer may be formed between the polarizer 100 and the polarizer protective film 200 . The adhesive layer may be formed of a conventional adhesive known to those skilled in the art.

The positive C layer 300 may be formed on the light incident surface of the polarizer 100 to allow light emitted from the IPS liquid crystal to be emitted to the polarizer 100 .

Although the positive C layer 300 will be described in detail below, since it is formed by coating the composition for the positive C layer on the polarizer, it is directly formed on the polarizer 100 . The "directly formed" means that any other adhesive layer, adhesive layer, optical layer, retardation film, compensation film, or the like is not interposed between the polarizer 100 and the positive C layer 300 . Accordingly, light emitted from the positive C layer may be directly incident on the polarizer 100 without being disturbed by any other optical layer, retardation film, compensation film, adhesive layer, or adhesive layer. Through this, it is possible to uniform the color of the left and right sides by compensating for the difference in the left and right visual perception by solving the problem of the left and right luminous difference when the polarizing plate is emitted through the IPS liquid crystal.

The positive C layer 300 may have a refractive index relationship of nz > nx ≒ ny at a wavelength of 550 nm. The positive C layer 300 has (nx-ny) of 0 to 0.00001, (ny-nz) is -0.0002 to -0.0001, for example -0.00019 to -0.0001, (nx-nz) is -0.0002 to -0.0001, For example, it may be -0.00019 to -0.0001.

The positive C layer 300 may have an in-plane retardation of 10 nm or less at a wavelength of 550 nm, preferably 5 nm or less, 4 nm or less, for example, 0 nm to 4 nm. Within the above range, when applied to an IPS liquid crystal display device, there may be an effect of resolving the non-uniformity of the left and right visual sensations. The positive C layer 300 may have a thickness direction retardation Rth of -180 nm to -10 nm at a wavelength of 550 nm, preferably -55 nm to -10 nm. Within the above range, when applied to an IPS liquid crystal display device, there may be an effect of resolving the non-uniformity of the left and right visual sensations.

The positive C layer 300 may have a thickness of 1 μm to 8 μm, preferably 2 μm to 6 μm, and more preferably 3 μm to 5.5 μm. In the above range, the positive C layer can thin the polarizing plate.

A polarizer protective film is formed on one surface of the polarizer and a positive C layer is formed on the other surface of the polarizer, and the polarizer protective film has a significantly greater thickness than the positive C layer. For example, the thickness ratio of the thickness of the polarizer protective film to the thickness of the positive C layer is 1:0.01 to 1:0.8, preferably 1:0.01 to 1:0.6, more preferably 1:0.04 to 1:0.25. can be However, the polarizing plate of the present invention can suppress warpage of the polarizing plate by using the positive C layer as the positive C layer to be detailed below. Therefore, as described above, the polarizing plate of the present invention can eliminate the non-uniformity of the left and right luminous sensations in the IPS liquid crystal display device, and obtain the effect of reducing the thickness and improving the warpage of the polarizing plate at the same time.

The polarizer protective film may not be provided on the light incident surface of the positive C layer.

In one embodiment, the polarizing plate may be formed of only a polarizer, a polarizer protective film laminated on the light emitting surface of the polarizer via an adhesive layer, and a positive C layer directly formed on the light incident surface of the polarizer.

In another embodiment, the polarizing plate consists of only a polarizer, a polarizer protective film laminated on the light emitting surface of the polarizer via an adhesive layer, a functional coating layer laminated on one surface of the polarizer protective film, and a positive C layer directly formed on the light incident surface of the polarizer can

Hereinafter, the positive C layer will be described.

The positive C layer may be an alignment-free non-liquid crystal layer. The positive C layer may be a single layer. The "single layer" means that the positive C layer is a layer prepared by forming a composition for forming the positive C layer by one application (or coating).

The positive C layer may be formed of a composition comprising at least one of a cellulose ester or a polymer thereof, an aromatic polymer. Preferably the positive C layer may be formed of a composition comprising a cellulose ester or a polymer thereof. When the composition for the positive C layer is coated on the polarizer, the surface of the polarizer itself is soft, so that when the composition for the positive C layer is coated, the polarization degree of the polarizer may be lowered. On the other hand, in the present invention, since the polarizer protective film serves as a support, the polarization degree can be maintained at the same level as before, even when the positive C layer is formed by directly coating the composition for the positive C layer on the polarizer. For example, the polarizing plate may have a polarization degree of 99% or more, for example, 99.9% or more, for example, 99.99% to 100%.

Cellulose ester refers to the condensation reaction product from the reaction of a hydroxyl group on cellulose with a carboxylic acid group of a carboxylic acid. Cellulose esters may be regioselectively or randomly substituted. Regioselectivity can be determined by determining the relative degree of substitution at C6, C3, C2 on the cellulose ester by carbon 13 NMR. Cellulose esters can be prepared by conventional methods by contacting a cellulose solution with one or more C1 to C20 acylating agents for a contact time sufficient to provide a cellulose ester having the desired degree of substitution and polymerization. Preferred acylating agents are one or more C1 to C20 straight or branched chain alkyl or aryl carboxylic acid anhydrides, carboxylic acid halides, diketones, or acetoacetic acid esters. Examples of anhydrides of carboxylic acids include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, hexanoic anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, lauric anhydride, palmitic anhydride, stearic anhydride, benzoic anhydride, substituted benzoic anhydride, phthalic anhydride, isophthalic anhydride. Examples of carboxylic acid halides include acetyl, propionyl, butyryl, hexanoyl, 2-ethylhexanoyl, lauroyl, palmitoyl, benzoyl, substituted benzoyl, and stearoyl chloride. Examples of the acetoacetic acid ester may include methylacetoacetate, ethylacetoacetate, propylacetoacetate, butylacetoacetate, tert-butylacetoacetate. Most preferred acylating agents are C2 to C9 straight or branched chain alkyl carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, 2-ethylhexanoic anhydride, nonanoic anhydride, stearic anhydride and the like.

Preferred examples of cellulose esters may include, but are not limited to, cellulose acetate (CA), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB).

The positive C layer may further include an additive having an aromatic fused ring in addition to a cellulose ester or a polymer thereof, or an aromatic polymer. The additive may serve to control the thickness direction retardation Rth expression rate and wavelength dispersion of the positive C layer. The aromatic fused ring may include naphthalene, anthracene, phenanthrene, pyrene, and Structure 1 or Structure 2 below. The additive may include, but is not limited to, 2-naphthyl benzoate, 2,6-naphthalene dicarboxylic acid diester of structure 3, naphthalene, abietic acid ester of structure 4, and the like:

<Structure 1>

<Structure 2>

<Structure 3>

(in the above, R is C1 to C20 alkyl or C6 to C20 aryl, n is an integer from 0 to 6)

<Structure 4>

(Wherein, R is C1 to C20 alkyl or C6 to C20 aryl)

The positive C layer may further include additives such as a plasticizer, a stabilizer, a UV absorber, an antiblock agent, a slip agent, a lubricant, a dye, a pigment, and a retardation improver, in addition to the additives described above.

The positive C layer may be formed by applying a composition for a positive C layer to the other side of the polarizer 100, one side of which is supported by the polarizer protective film 200, to form a coating layer, and drying and/or curing the formed coating layer. .

The composition for the positive C layer may further include a conventional solvent known to those skilled in the art in order to improve the applicability of the composition for the positive C layer in addition to the above-described cellulose ester or polymer thereof, and an aromatic polymer. For example, the solvent may include at least one of ketone solvents such as methyl isopropyl ketone and acetone, ether solvents such as propylene glycol methyl ether (PGME), and propylene glycol methyl ether acetate (PGMEA) as an organic solvent. have.

The positive C layer is a non-tacky layer with no tackiness. Accordingly, although not shown in FIG. 1 , an adhesive layer is formed on the lower surface of the positive C layer 300 , that is, on the surface opposite to the polarizer 100 , so that the polarizing plate can be laminated on the IPS liquid crystal panel.

In one embodiment, the polarizing plate may consist of only a polarizer, a polarizer protective film laminated on one side of the polarizer via an adhesive layer, a positive C layer directly formed on the other side of the polarizer, and an adhesive layer formed on the other side of the positive C layer.

In another embodiment, the polarizing plate is a polarizer, a polarizer protective film laminated on one side of the polarizer via an adhesive layer, a functional coating layer laminated on one side of the polarizer protective film, a positive C layer and a positive C layer directly formed on the other side of the polarizer It may consist only of an adhesive layer formed on the other surface.

Hereinafter, an IPS liquid crystal display device of the present invention will be described.

The IPS liquid crystal display device of the present invention may include a polarizing plate for the IPS liquid crystal display device of the present invention. The polarizing plate for an IPS liquid crystal display of the present invention may be used as a viewing-side polarizing plate or a light-source-side polarizing plate for an IPS liquid crystal panel. Preferably, it can be used as a viewing-side polarizing plate.

In one embodiment, the IPS liquid crystal display device includes an IPS liquid crystal panel, a viewer-side polarizing plate formed on a light exit surface of the IPS liquid crystal panel, and a light source-side polarizing plate formed on a light incident surface of the IPS liquid crystal panel, wherein the viewer-side polarizing plate is the present invention may include a polarizing plate of In this case, the positive C layer may be positioned between the polarizer and the IPS liquid crystal panel. In this case, the light source-side polarizing plate includes a polarizer; a first polarizer protective film formed on the light emitting surface of the polarizer; and a second polarizer protective film formed on the light incident surface of the polarizer. The first polarizer protective film may be an isotropic film or a retardation film of Re 10 nm or less. The second polarizer protective film may include the above-described high retardation or ultra-high retardation polarizer protective film.

In another embodiment, the IPS liquid crystal display device includes an IPS liquid crystal panel, a viewer-side polarizing plate formed on a light exit surface of the IPS liquid crystal panel, and a light source-side polarizing plate formed on a light incident surface of the IPS liquid crystal panel, the viewer-side polarizing plate and the light source The side polarizing plate may include the polarizing plate of the present invention. In this case, the positive C layer may be positioned between the polarizer and the IPS liquid crystal panel.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example One

poet side Polarizer manufacturing

A polarizer (thickness: 12 μm) was prepared by stretching the polyvinyl alcohol film 3 times at 60° C., adsorbing iodine, and stretching 2.5 times in an aqueous boric acid solution at 40° C. A composition for forming a positive C layer was prepared by uniformly mixing methyl ethyl ketone with VM (Eastman, cellulose acetate, including additives). A polyethylene terephthalate (PET) film (Toyobo), thickness: 80 μm, wavelength 550 nm, Re: 8400 nm, Rth: 9800 nm) is attached to the upper surface of the prepared polarizer, and the prepared positive C layer is attached to the lower surface of the polarizer The composition was applied to a predetermined thickness and dried (or cured) at 60° C. for 3 minutes to prepare a polarizing plate in which a PET film, an adhesive layer, a polarizer, and a positive C layer were sequentially formed. The thickness, Re, and Rth of the positive C layer are shown in Table 1 below. The prepared polarizing plate was used as a viewing-side polarizing plate.

light source side Polarizer manufacturing

A polarizer was manufactured in the same manner as above. A triacetyl cellulose (TAC) film (KC2UAW, Konica Minolta Opto, Inc., thickness: 40㎛) was adhered to the upper surface of the prepared polarizer, and a polyethylene terephthalate (PET) film (Toyobo Corporation) was attached to the lower surface of the polarizer. , thickness: 80 μm, wavelength 550 nm, Re: 8400 nm, Rth: 9800 nm) was adhered to prepare a light source-side polarizing plate.

Liquid crystal module manufacturing

The above-prepared viewer-side polarizing plate was adhered to the light emitting surface of the IPS liquid crystal-containing liquid crystal panel through an adhesive layer. At this time, the positive C layer of the viewer-side polarizing plate was adhered to the liquid crystal panel. A liquid crystal module was prepared by attaching the light source-side polarizing plate prepared above to the light incident surface of the liquid crystal panel containing IPS liquid crystal through an adhesive layer. At this time, the TAC film of the light source-side polarizing plate was adhered to the liquid crystal panel.

Example 2

In Example 1, a viewing side polarizing plate, a light source side polarizing plate, and a liquid crystal module were manufactured in the same manner as in Example 1, except that the thickness and retardation of the positive C layer were changed as shown in Table 1 below.

Example 3

poet side Polarizer manufacturing

A viewer-side polarizing plate was manufactured in the same manner as in Example 1.

light source side Polarizer manufacturing

In the same manner as in Example 1, a polarizing plate in which a positive C layer, a polarizer, an adhesive layer, and a PET film were sequentially formed was manufactured.

Liquid crystal module manufacturing

The above-prepared viewer-side polarizing plate was adhered to the light emitting surface of the liquid crystal panel containing IPS liquid crystal through an adhesive layer. At this time, the positive C layer of the viewer-side polarizing plate was adhered to the liquid crystal panel. A liquid crystal module was prepared by attaching the light source-side polarizing plate prepared above to the light incident surface of the liquid crystal panel containing IPS liquid crystal through an adhesive layer. At this time, the positive C layer of the light source-side polarizing plate was adhered to the liquid crystal panel.

Example 4

In Example 3, the viewer-side polarizing plate, the light-source-side polarizing plate, and the liquid crystal module were performed in the same manner as in Example 3, except that the thickness and phase difference of the positive C layer of each of the viewer-side polarizing plate and the light-source-side polarizing plate were changed as shown in Table 1 below. was prepared.

comparative example One

A polarizer was manufactured in the same manner as in Example 1.

A PET film (Toyobo), thickness: 80㎛, wavelength 550nm, Re:8400nm, Rth:9800nm) is adhered to the upper surface of the polarizer, and a TAC film (KC2UAW, Konica Minolta Opto, Inc., thickness) is attached to the lower surface of the polarizer. : 40 μm) to prepare a viewing-side polarizing plate. TAC film (KC2UAW, Konica Minolta Opto, Inc., thickness: 40㎛) is adhered to the upper surface of the polarizer, PET film (Toyobo Corporation), thickness: 80㎛, Re:8400nm at wavelength 550nm, on the lower surface of the polarizer Rth:9800nm) was adhered to prepare a light source-side polarizing plate.

The above-prepared viewer-side polarizing plate was adhered to the light emitting surface of the IPS liquid crystal-containing liquid crystal panel through an adhesive layer. At this time, the TAC film of the viewer-side polarizing plate was adhered to the liquid crystal panel. A liquid crystal module was prepared by attaching the light source-side polarizing plate prepared above to the light incident surface of the liquid crystal panel containing IPS liquid crystal through an adhesive layer. At this time, the TAC film of the light source-side polarizing plate was adhered to the liquid crystal panel.

comparative example 2

In Comparative Example 1, a PET film (Toyobo Corporation), thickness: 60 μm, wavelength 550 nm, Re: 6100 nm, Rth: 7100 nm) was used instead of the PET film in each of the viewing side polarizing plate and the light source side polarizing plate. A viewing side polarizing plate, a light source side polarizing plate, and a liquid crystal panel were manufactured.

The following physical properties were evaluated for the viewer-side polarizing plate and liquid crystal module prepared in Examples and Comparative Examples, and the results are shown in Table 1, FIG. 2, and FIG. 3 below.

(1) Polar angle left and right visual perception: The viewer-side polarizing plates prepared in Examples and Comparative Examples were assembled as a viewer-side polarizing plate of an IPS liquid crystal. Using the EZ-Contrast XL-88 equipment, the polar angle left and right visual sensations were evaluated by specifying the left (20 degrees) / right (160 degrees) angles in the black color azimuth of 80 degrees. When the left and right luminous sensations were evaluated with the naked eye, it was evaluated as good when the left and right luminous differences were not confirmed, and bad when the left and right luminous differences were confirmed.

(2) Polarization degree (unit: %): The degree of polarization was measured for the viewer-side polarizing plates prepared in Examples and Comparative Examples. The transmittance for each wavelength was measured with a V-7100 UV-VIS Spectrophotometer to obtain a calculated polarization value.

(3) Warp (unit: mm): The viewer-side polarizing plate prepared in Examples and Comparative Examples was cut so that the MD of the polarizer x the TD of the polarizer was 139.2mm x 219.8mm, and the adhesive layer on the glass plate (length x width x thickness 143mm x 224mm x 0.5T) A specimen was prepared by laminating as a medium. The specimen is placed on the bottom and left at 60° C. for 240 hours, and then 8 points are measured from the bottom, and the highest height of the specimen is obtained as an average value of 2 points. After measuring in the same manner as above for a total of three specimens, a final average was obtained.

Example
comparative example
One 2 3 4 One 2 poet side
Polarizer Polarizer top surface
PET
(80) PET
(80) PET
(80) PET
(80) PET
(80) PET
(60) Polarizer lower surface
positive C
(3) positive C
(5) positive C
(3) positive C
(5) TAC
(40) TAC
(40) light source side
Polarizer Polarizer top surface
TAC
(40) TAC
(40) positive C
(3) positive C
(5) TAC
(40) TAC
(40) Polarizer lower surface
PET
(80) PET
(80) PET
(80) PET
(80) PET
(80) PET
(60) Thickness Ratio* 0.04 0.06 0.04 0.06 0.5 0.67 positive C layer Re(nm) 1.21 1.74 1.21 1.74 - - Rth(nm) -30 -40 -30 -40 - - Right and left
tick left x 0.257 0.2765 0.257 0.237 0.351 0.337 y 0.249 0.2742 0.246 0.221 0.348 0.334 right x 0.237 0.2523 0.228 0.213 0.312 0.296 y 0.235 0.2585 0.216 0.192 0.296 0.275 Left and right luminous gap Good Good Good Good error error Polarization degree 99.996 99.996 99.996 99.996 99.996 99.996 warp 0.6 0.5 0.5 0.5 1.3 1.3

*Thickness ratio: In the viewer-side polarizing plate, the ratio of the thickness of the positive C layer of the lower surface of the polarizer to the protective film of the upper surface of the polarizer or the thickness ratio of the protective film of the lower surface of the polarizer according to the protective film of the upper surface of the polarizer

* In Table 1, the number in parentheses means the thickness, and the unit is μm.

As shown in Table 1, it can be seen that the polarizing plate of the present invention improves the difference in visual perception when applied as a viewer-side polarizing plate to an IPS liquid crystal display device or as both a viewer-side polarizing plate and a light source-side polarizing plate. Referring to FIG. 2 , in Examples 1 to 4, it can be confirmed that the color coordinates x and y of Comparative Examples 1 to 2 are shifted toward blue. Referring to FIG. 3 , it can be seen that the luminance is uniformly displayed on the left and right sides of the embodiment. In addition, the polarizing plate of the present invention can secure the same or more polarization degree compared to the polarizing plate of the conventional protective film-polarizer-protective film, even though the positive C layer is formed by directly coating the composition for the positive C layer on the polarizer, and there is also an effect of improving the warpage .

On the other hand, the polarizing plates of Comparative Examples 1 and 2, which do not have the positive C layer of the present invention, when applied to an IPS liquid crystal display device, showed little improvement in the visual perception difference between the left and the right, which can be seen through Tables 1, 2, and 3 above. can

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

Claims (13)

a polarizer, a polarizer protective film formed on a light emitting surface of the polarizer, and a positive C layer formed on a light incident surface of the polarizer,
The positive C layer is formed directly on the polarizer,
the positive C layer is a non-liquid crystal layer,
When the absorption axis of the polarizer is 0°, the slow axis direction of the polarizer protective film is -5° to 5°,
The polarizer protective film has an in-plane retardation Re of 6,000 nm or more at a wavelength of 550 nm, a polarizing plate for an IPS liquid crystal display.
The polarizing plate for an IPS liquid crystal display according to claim 1, wherein a polarizer protective film is not provided on the light incident surface of the positive C layer.
The IPS according to claim 1, wherein the polarizing plate consists of only the polarizer, the polarizer protective film laminated on the light emitting surface of the polarizer via an adhesive layer, and the positive C layer formed directly on the light incident surface of the polarizer. Polarizing plate for liquid crystal display.
According to claim 1, wherein the polarizing plate is the polarizer, the polarizer protective film laminated on the light emitting surface of the polarizer via an adhesive layer, a functional coating layer laminated on one surface of the polarizer protective film, directly on the light incident surface of the polarizer A polarizing plate for an IPS liquid crystal display that is made of only the positive C layer formed with.
delete The polarizing plate for an IPS liquid crystal display according to claim 1, wherein the positive C layer is formed of at least one of a cellulose ester or a polymer thereof and an aromatic polymer.
The polarizing plate for an IPS liquid crystal display according to claim 6, wherein the cellulose ester includes at least one of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.
The polarizing plate for an IPS liquid crystal display according to claim 1, wherein the polarizing plate has a polarization degree of 99% or more.
The polarizing plate for an IPS liquid crystal display according to claim 1, wherein the positive C layer has an in-plane retardation Re of 10 nm or less at a wavelength of 550 nm.
delete The polarizing plate for an IPS liquid crystal display according to claim 1, wherein the polarizer protective film has a thickness direction retardation Rth of 12,000 nm or less at a wavelength of 550 nm.
The polarizing plate for an IPS liquid crystal display according to claim 1, wherein an adhesive layer is further formed on the light incident surface of the positive C layer.
An IPS liquid crystal display comprising a polarizing plate for an IPS liquid crystal display according to any one of claims 1 to 4, 6 to 9, 11, and 12.

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