KR20140074171A - Polarizing plate and liquid crystal comprising the same display - Google Patents

Abstract

The present invention relates to a polarizing plate and a liquid crystal display device having the same. More specifically, a polarizing plate includes a first protective film, a polarizer, a second protective film, and an adhesive layer sequentially layered, wherein at least one protective film is uniaxial oriented in a machine direction (MD), a front phase difference value (RO) is greater than 100 nm and less than 300 nm, and Equation 1, 0.0235RO - 7.35 <= NZ <= -0.015RO + 6.5 (herein, RO is a front phase difference value, and NZ is a refractive index ratio), is satisfied. Since the protective film for the polarizing plate has a high phase difference based on lower price than that of the related art, the protective film has good price competitiveness and prevents versicolor stains to maintain the quality of an image such as securing of viewing angle.

Description

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

The present invention relates to a polarizing plate capable of suppressing iridescence caused by use of a protective film having a high retardation, and a liquid crystal display including the polarizing plate.

Liquid crystal displays (LCDs) have the highest market share among flat panel displays and replace cathode-ray tubes (CRTs), which are the most widely used image display devices.

Liquid crystal display devices have improved many technical disadvantages at the initial stage of development, and now they are trying to expand their market share by increasing price competitiveness. Thus, a polarizing plate which is a core component of a liquid crystal display device has been attempted.

A typical method for improving the price competitiveness of a polarizer is to use an inexpensive polarizer protective film.

Polarizer protective films are primarily intended to protect mechanically weak polarizers. In recent years, a protective film laminated on the side of a liquid crystal panel of a polarizer has been added with a function of compensating the viewing angle by giving an appropriate retardation through stretching. It is common for the engineers of the art that the retardation value does not affect the optical characteristics in the case of the protective film laminated on the other side of the liquid crystal panel in the double polarizer.

Typically, triacetyl cellulose (TAC) or the like is used as such a protective film. Triacetyl cellulose (TAC) is usually prepared by a casting process, and a negative C plate is formed while the solvent is volatilized. Such triacetyl cellulose (TAC) is much higher in price than general plastic film.

Attempts have been made to use a low-cost plastic film instead of triacetylcellulose (TAC) as a polarizer protective film.

However, inexpensive plastic films generally have a large retardation because they are stretched at a high magnification in order to increase the yield, and the liquid crystal display devices including the plastic films have a disadvantage in that image quality is deteriorated due to iridescence.

As a method for suppressing rainbow stains caused by a film stretched at a high magnification, there is proposed a method of treating a surface of a film stretched at a high magnification or adding a dispersing agent in a film stretched at a high magnification . However, also in this case, there is a problem that the quality of the image is deteriorated or the manufacturing cost is increased.

An object of the present invention is to provide a polarizing plate which can be applied as a protective film of a polarizer at a low cost and having a high retardation without degrading image quality.

It is another object of the present invention to provide a liquid crystal display device having the polarizing plate.

In order to achieve the above object, the present invention provides a liquid crystal display device comprising a first protective film, a polarizer, a second protective film and a pressure-sensitive adhesive layer laminated in this order. Wherein the at least one protective film is uniaxially stretched in the MD direction and has a front retardation value (RO) of more than 100 nm and less than 300 nm, and satisfies the following formula (1).

(Where RO is the front retardation value and NZ is the refractive index ratio).

Preferably, the NZ may be NZ > 1.

Preferably, the NZ may be NZ < 0.

The at least one protective film may be a first protective film and a second protective film.

(PS), polycarbonate (PC), polysulfone (PSF), polyether sulfone (PSF), polyether sulfone And polymethyl methacrylate (PMMA).

The first protective film may be formed of a material selected from the group consisting of a cycloolefin polymer (COP), a cycloolefin copolymer (COC), a polyethylene terephthalate (PET), a polypropylene (PP), a polystyrene (PS), a polycarbonate (PC), a polysulfone And polymethyl methacrylate (PMMA).

The first protective film may include a surface treatment layer on the opposite side of the surface to be bonded with the polarizer.

The present invention also provides a liquid crystal display device including the polarizer.

The liquid crystal display device may include a polarizing backlight.

The polarizing plate of the present invention can be applied to a low-priced film having a high retardation as a protective film of a polarizer, and thus is excellent in price competitiveness. When a polarizer including a conventional low-priced film having a high retardation is applied to a liquid crystal display device, There is an advantage that the iridescence caused by the phase difference can be suppressed to maintain the quality of the image (to secure the viewing angle).

1 is a vertical sectional view of a polarizing plate according to the present invention,
2 shows the structure of a liquid crystal display device according to the first embodiment of the present invention,
FIG. 3 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device according to Example 1 of the present invention,
FIG. 4 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device according to the second embodiment of the present invention,
FIG. 5 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device according to the third embodiment of the present invention,
FIG. 6 is a graph showing the degree of omnidirectional rainbow facial generation when a voltage is applied to the liquid crystal display device according to the fourth embodiment of the present invention,
FIG. 7 is a graph showing the degree of omnidirectional rainbow facial generation when a voltage is applied to the liquid crystal display device according to the fifth embodiment of the present invention,
8 is a graph illustrating the degree of omnidirectional irregularity of a face when a voltage is applied to the liquid crystal display device of Example 6 according to the present invention,
FIG. 9 is a graph showing the degree of omnidirectional rainbow facial generation when a voltage is applied to the liquid crystal display device according to Example 7 of the present invention,
FIG. 10 is a graph showing the degree of irregular surface generation of a rainbow when a voltage is applied to the liquid crystal display device according to the eighth embodiment of the present invention,
FIG. 11 is a graph illustrating the degree of irregular surface generation of a rainbow when a voltage is applied to a liquid crystal display device according to Example 9 of the present invention,
12 is a view showing the generation of iridescent face in all directions when a voltage is applied to the liquid crystal display device according to Embodiment 10 of the present invention,
13 is a view showing the generation of a rainbow facial forehead in a liquid crystal display device according to an eleventh embodiment according to the present invention,
FIG. 14 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device of Example 12 according to the present invention,
15 is a view showing the generation of a rainbow facial forehead in a liquid crystal display device according to a thirteenth embodiment according to the present invention,
16 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device according to the fourteenth embodiment of the present invention,
17 is a graph showing the degree of omnidirectional rainbow facial generation when a voltage is applied to the liquid crystal display device of Example 16 according to the present invention,
18 shows the degree of omnidirectional iridescent face generation at the time of voltage application of the liquid crystal display device of Comparative Example 1 according to the present invention,
FIG. 19 is a graph showing the degree of occurrence of omnidirectional rainbow faces when a voltage is applied to the liquid crystal display device of Comparative Example 2 according to the present invention.

The present invention relates to a polarizing plate capable of suppressing iridescence caused by use of a protective film having a high retardation, and a liquid crystal display including the polarizing plate.

A rainbow stain is a phenomenon in which a phase difference value varies greatly according to an incident angle when polarized light is transmitted to a phase difference layer, and a difference in phase difference value is large depending on a wavelength.

Since a high-retardation film is usually produced by high-magnification stretching, a large retardation value and a large change in retardation value according to an incident angle causes rainbow stains when the polarized light passes through. Furthermore, since most of the films have regular wavelength dispersibility, the change of the retardation value according to the wavelength becomes larger.

The present invention applies a high-retardation film as a protective film of a polarizing plate, and controls the stretching method and the refractive index ratio of the high-retardation film to a specific range to suppress the occurrence of rainbow stains. The present invention refers to the occurrence of rainbow stains due to a high-retardation film as a high-phase difference.

Hereinafter, the present invention will be described in detail.

The polarizing plate of the present invention is laminated in the order of a first protective film, a polarizer, a second protective film and a pressure-sensitive adhesive layer. The at least one protective film is uniaxially stretched in the machine direction (MD), and the front retardation value (RO) is more than 100 nm and less than 300 nm.

[Equation 1]

 (Where RO is the front retardation value and NZ is the refractive index ratio).

In the above equation (1), NZ is preferably NZ > 1 or NZ <

Generally, when NZ is 0 or 1, it is recognized that the optical axis is located in the plane and the rainbow disappears, and thus it is recognized that the present invention is obvious to the person skilled in the art. do.

When the liquid crystal cell is in the VA mode, it is preferable that the first protective film satisfies the above condition.

In the case where the liquid crystal cell is a mode in which the liquid crystal rotates in the plane, such as an IPS mode, an FFS mode, a PLS mode, and an ADS mode, the polarizing plate may have a structure in which the second protective film alone or the same first protective film and second protective film It is preferable to use one that satisfies the conditions. It is more preferable to use the same first protective film and second protective film.

Usually, the film is produced by a stretching process, and as the stretching progresses much more, the retardation value becomes larger and the manufacturing cost per unit area of the film becomes lower. Triacetyl cellulose (TAC), which is a typical protective film of the prior art, exhibits optical characteristics with a front retardation value (RO) of 10 nm or less and a thickness retardation value (Rth) of 30 to 50 nm without stretching. These optical properties are significantly lower in retardation than the common plastic films we see.

The following equations (2) to (4) define the front retardation value (RO), the thickness direction retardation value (Rth) and the refractive index ratio (NZ), which are optical characteristics of the first protective film and the second protective film. At this time, the optical characteristic is about the propagation field in the visible light region.

(Where Nx and Ny are the surface refractive indexes, Nx &gt; = Ny, and d is the thickness of the film)

(Where Nx and Ny are surface refractive indices Nx &gt; = Ny, Nz is refractive index in the thickness direction of the film, and d is the thickness of the film)

(Where Nx and Ny are the surface refractive indexes, Nx &gt; = Ny, and Nz is the refractive index in the thickness direction of the film)

The present invention is characterized in that a highly stretched film is used as a protective film of a polarizer in place of a protective film whose retardation value is limited to a specific range in consideration of optical properties such as rainbow stains.

The highly stretched film has a front retardation value (RO) of more than 100 nm and less than 300 nm, and is stretched at a high magnification and the product unit price per unit area is low.

The protective film applied to the present invention must be uniaxially stretched in the machine direction (MD). The MD direction refers to a direction in which a film existing in a roll state before being bonded to a polarizer is unwound or rolled in a roll, and uniaxial stretching means a film oriented by stretching only in one direction.

When the film is uniaxially stretched in the MD direction, the extension line of the optical axis does not extend out of the film surface but exists in the surface, and high phase difference mura is not generated.

The high phase difference mura occurs at a time when the phase difference change with time is severe. Although the light passing through the optical axis does not have a phase difference, the phase difference between the optical axis and the optical axis changes greatly, so that a high phase shift is observed at a time near the optical axis.

Further, the protective film of the present invention has a front retardation value (RO) of more than 100 nm and less than 300 nm, and satisfies the above-mentioned formula (1). When the refractive index ratio is out of the range of the formula (1), the viewing angle becomes narrow. Preferably, the refractive index ratio (NZ) of the protective film is 0 or 1.

Specifically, when the liquid crystal cell is in the VA mode, a film in which the front retardation value (RO) and the refractive index ratio (NZ) are specified in the range of the present invention is used as the first protective film, and the second protective film is in the range Non-limiting films can be used.

In the case where the liquid crystal cell is an IPS mode, an FFS mode, a PLS mode, and an ADS mode, a film in which the front retardation value RO and the refractive index ratio NZ are specified by the range of the present invention is used as the second protective film, The protective film may be a film not limited to the scope of the present invention.

In addition, a film in which the front retardation value (RO) and the refractive index ratio (NZ) of the first protective film and the second protective film are specified in the range of the present invention can be used.

The first and second protective films of the present invention are polarizer protective films for protecting the polarizers because they are mechanically weak. Further, the second protective film may have a function of compensating the retardation.

The first and second protective films differ in the moisture permeability depending on the type of resin and can be selected depending on transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like.

Specifically, the first and second protective films may be formed of a material selected from the group consisting of a cycloolefin polymer (COP), a cycloolefin copolymer (COC), a polyethylene terephthalate (PET), a polypropylene (PP), a polystyrene (PS), a polycarbonate Sulfone (PSF) and polymethyl methacrylate (PMMA) may be used.

The thickness of the first and second protective films is not particularly limited. However, when the thickness is too small, the strength and workability are deteriorated. When the thickness is too large, transparency deteriorates or the curing time increases after lamination to the polarizer. The thickness of the protective film is preferably 5 to 200 占 퐉, preferably 10 to 150 占 퐉, more preferably 20 to 100 占 퐉.

A polarizer is an optical film that serves to convert incident natural light into a desired single polarization state (linearly polarized light state), and a film made of a polyvinyl alcohol resin and having a dichroic dye adsorbed and oriented can be used.

The polyvinyl alcohol resin constituting the polarizer can be produced by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include copolymers of vinyl acetate and other monomers copolymerizable with vinyl acetate in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Specific examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, acrylamides having an ammonium group, and the like. In addition, the polyvinyl alcohol resin may be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of saponification of the polyvinyl alcohol resin may be generally 85 to 100 mol%, preferably 98 mol% or more. The polymerization degree of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000.

Such a polyvinyl alcohol-based resin is formed into a film and used as a polarizer. The film-forming method of the polyvinyl alcohol-based resin is not particularly limited, and various known methods can be used. The film thickness of the polyvinyl alcohol-based resin is not particularly limited, and may be, for example, 3 to 150 mu m.

The polarizer is usually produced by a process of uniaxially stretching a polyvinyl alcohol film as described above, dyeing with a dichroic dye and adsorbing, treating with an aqueous boric acid solution, and washing and drying.

The step of uniaxially stretching the polyvinyl alcohol film may be performed before dyeing, concurrently with dyeing, or after dyeing. If uniaxial stretching is carried out after dyeing, it may be carried out before the boric acid treatment or during the boric acid treatment. Of course, it is also possible to perform uniaxial stretching by a plurality of steps each of which is combined. As the uniaxial stretching, other rolls or rolls having different circumferences may be used, and may be dry stretching by stretching in air or wet stretching by stretching in the state of being swollen by a solvent. The stretching ratio is usually 3 to 8 times.

In the step of dyeing a stretched polyvinyl alcohol film with a dichroic dye, for example, a method of immersing a polyvinyl alcohol film in an aqueous solution containing a dichroic dye may be used. A specific example of the dichroic dye is iodine or a dichroic organic dye. It is preferable that the polyvinyl alcohol film is pre-immersed in water before dyeing to swell.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based film is dipped in an aqueous solution for dyeing usually containing iodine and potassium iodide may be used. Usually, the content of iodine in an aqueous solution for dyeing is 0.01 to 1 part by weight with respect to 100 parts by weight of water (distilled water), and the content of potassium iodide is 0.5 to 20 parts by weight with respect to 100 parts by weight of water. The temperature of the aqueous solution for dyeing is usually 20 to 40 占 폚, and the immersion time, for example, the dyeing time is usually 20 to 1800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a polyvinyl alcohol film is dipped in an aqueous solution for dyeing usually containing a water-soluble dichroic organic dye is used. The content of the dichroic organic dye in the dyeing aqueous solution is usually 1 x ^10-4 to 10 parts by weight, preferably 1 x ^10-3 to 1 part by weight based on 100 parts by weight of water. The aqueous solution for dyeing may further contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution for dyeing is usually 20 to 80 캜, and the immersion time, for example, the dyeing time is usually 10 to 1,800 seconds.

The step of treating the dyed polyvinyl alcohol film with boric acid can be carried out by immersing it in an aqueous solution containing boric acid. The content of boric acid in an aqueous solution containing boric acid is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight based on 100 parts by weight of water. The aqueous solution containing boric acid when iodine is used as the dichroic dye is preferably contained in an amount of 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of water. The boric acid-containing aqueous solution preferably has a temperature of 50 DEG C or higher, preferably 50 to 85 DEG C, more preferably 60 to 80 DEG C, and the immersing time is 60 to 1,200 seconds, preferably 150 to 600 seconds, Preferably 200 to 400 seconds.

After the boric acid treatment, the polyvinyl alcohol film is washed with water and dried. The water treatment can be carried out by immersing the boric acid-treated polyvinyl alcohol-based film in water. The water temperature during the water treatment is 5 to 40 ° C, and the immersion time is 1 to 120 seconds. After washing with water, the polarizer can be obtained by drying. The drying treatment is usually carried out using a hot air dryer or a far infrared ray heater. The drying treatment temperature is usually 30 to 100 ° C, preferably 50 to 80 ° C, and the drying time is usually 60 to 600 seconds, 600 seconds is good.

The thickness of the polarizer may be from 3 to 40 mu m.

An adhesive layer is formed between the polarizer and the first protective film, and between the polarizer and the second protective film. For example, an aqueous adhesive or a UV curable adhesive may be used as the adhesive layer.

The kind of the adhesive is not particularly limited as long as it can sufficiently bond the polarizer and the protective film, is excellent in optical transparency, and does not change with time, such as yellowing. For example, the adhesive may be an aqueous adhesive composition containing a polyvinyl alcohol resin and a crosslinking agent .

Examples of the polyvinyl alcohol resin contained in the water-based adhesive composition include a polyvinyl alcohol resin or a polyvinyl alcohol resin having an acetoacetyl group. Among these, the polyvinyl alcohol resin having an acetoacetyl group is preferably a polyvinyl alcohol having a highly reactive functional group It is preferable from the viewpoint of improving the durability of the polarizing plate as an alcohol-based adhesive.

The resin contained in the UV curable adhesive composition is generally used in the art, and an epoxy resin, an acrylic resin, or the like can be used.

Further, surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame (flame) treatment or saponification treatment can be appropriately performed on the surface of the polarizer to be bonded to the protective film.

As a method for bonding a protective film to a polarizer with an adhesive, a method commonly known in the art can be used. For example, a polarizer, a protective film Or a method in which an adhesive is applied to the joint surfaces of both of them and the joints are applied. Here, the "softening" is a method in which a polarizer or a protective film as an object to be coated is moved in a substantially vertical direction, a substantially horizontal direction, or an inclined direction between them, and an adhesive is applied to the surface of the object to be coated. After the adhesive is applied, the polarizer and the protective film are bonded to each other through a bonding roll or the like.

The pressure-sensitive adhesive layer may be formed of a pressure-sensitive adhesive composition commonly used in the art, which contains a pressure-sensitive adhesive resin and a crosslinking agent as a layer for bonding with the liquid crystal cell.

The pressure-sensitive adhesive resin included in the pressure-sensitive adhesive composition may be an acrylic, silicone, rubber, urethane, polyester or epoxy copolymer, and preferably an acrylic copolymer. In addition, the pressure-sensitive adhesive composition may contain a known antistatic agent such as an alkali metal salt, an ionic compound, a conductive polymer, a metal oxide, CNT and the like. Of these, it is more preferable to include an ionic compound.

The method of laminating the pressure-sensitive adhesive layer on the polarizing plate is not particularly limited as long as it is a method commonly used in the art. For example, the pressure-sensitive adhesive composition may be coated on the antistatic coating layer formed on the polarizer protective film by using the same method as the method of applying the antistatic coating liquid composition, followed by drying and laminating. Alternatively, a pressure-sensitive adhesive layer may be formed on the silicone-coated release film by the same application method as described above, and then the pressure-sensitive adhesive sheet may be laminated on the antistatic coating layer formed on the polarizer protective film by using a roll pressing apparatus. When the ultraviolet curable compound is contained in the pressure-sensitive adhesive composition as a crosslinking agent, it is preferable to irradiate ultraviolet rays after the pressure-sensitive adhesive composition is applied or laminated using a roll-pressing apparatus.

The thickness of the pressure-sensitive adhesive layer can be adjusted in accordance with the adhesive strength, and is preferably 3 to 100 탆, more preferably 10 to 100 탆.

In the liquid crystal display device of the present invention, the polarizing plate may be provided on both the upper plate, the lower plate, and the upper and lower plates. When the polarizing plate is provided on the upper plate or the lower plate, the other polarizing plate is generally used in the art, and a protective film may be bonded to both surfaces of the polarizing plate.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  One

Actual data such as each optical film, liquid crystal cell and backlight according to the present invention were laminated on a TECH WIZ LCD in a structure as shown in Fig. Liquid crystal cell parameters of the 55-inch PS-VA mode liquid crystal display device were laminated on the TECH WIZ LCD.

The liquid crystal display device was composed of a polarizing backlight, a lower plate polarizing plate PS-VA mode liquid crystal cell, and a top plate polarizing plate. The upper plate and the lower plate polarizer were laminated in this order from the liquid crystal cell side in the order of the pressure-sensitive adhesive layer, the second protective film, the adhesive layer, the polarizer, the adhesive layer and the first protective film.

The polarizer imparts a polarizer function to the PVA through stretching and dyeing, and the absorption axis of the backlight side polarizer is stacked in the vertical direction when viewed from the viewer side, and the absorption axis of the viewer side polarizer is arranged in the horizontal direction.

라고 할 때 하기 수학식 5 내지 9에 의해 정의된다. The polarizing performance of the polarizer was 99.9% or more and the visibility-based single-beam transmittance was 41% or more in the visible light region of 370 to 780 nm. The transmittance of the transmission axis according to the wavelength is denoted by TD (λ), the transmittance of the absorption axis with respect to wavelength is denoted by MD (λ), and the visibility correction value defined in JIS Z 8701: 1999

And is defined by the following equations (5) to (9).

Each first protective film of the upper plate and the lower plate was laminated with a polyethylene terephthalate (PET) film uniaxially stretched in the MD direction and having a front retardation value (RO) of 250 nm and a refractive index ratio (NZ) of 1 at a light source of 589 nm . The first protective film was laminated such that the absorption axis of the adjacent polarizer and the direction of the slow axis were perpendicular to each other.

Each second protective film of the upper plate and the lower plate is a protective film having a function of compensating for retardation and is a cycloolefin polymer (COP) having a frontal retardation value (RO) of 50 nm and a thickness retardation value (Rth) The film was laminated.

The upper plate polarizer and the lower plate polarizer each formed an acrylic adhesive layer between protective films on both sides.

FIG. 3 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device and calculating iridescent irregularities in all directions. Specifically, as a result of expressing colors in all directions in a contour map (Color Contour Map), iridescent irregularities I could confirm that I did not.

Example  2: VA mode

The first protective film of each of the upper and lower plates was uniaxially stretched in the MD direction and had a front retardation value (RO) of 250 nm at a light source of 589 nm and a refractive index ratio (NZ) of 0 Modified polystyrene (PS) films were laminated.

FIG. 4 shows that rainbow stains were not generated at all as a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions.

Example  3: VA mode

The first protective film of each of the upper and lower plates was uniaxially stretched in the MD direction and had a front retardation value (RO) of 150 nm at a light source of 589 nm and a refractive index ratio (NZ) of 1 A polyethylene terephthalate (PET) film was laminated.

FIG. 5 shows a result of calculating a rainbow stain in all directions by applying a voltage to the liquid crystal cell of the liquid crystal display device, and it was confirmed that rainbow stains did not occur at all.

Example  4: VA mode

The first protective film of each of the upper and lower plates was uniaxially stretched in the MD direction and had a front retardation value RO of 150 nm at a light source of 589 nm and a refractive index ratio NZ of 0 Modified polystyrene (PS) films were laminated.

FIG. 6 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  5: VA mode

Each first protective film of the upper plate and the lower plate was uniaxially stretched in the MD direction and had a front retardation value RO of 200 nm at a light source of 589 nm and a refractive index ratio NZ of 2 A polyethylene terephthalate (PET) film was laminated.

FIG. 7 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  6: VA mode

The first protective film of each of the upper and lower plates was uniaxially stretched in the MD direction and had a front retardation value (RO) of 290 nm at a light source of 589 nm and a refractive index ratio (NZ) of 1.5 A polyethylene terephthalate (PET) film was laminated.

FIG. 8 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate iridescent blobs in all directions, and it was confirmed that iridescent irregularities did not occur at all.

Example  7: VA mode

The first protective film of each of the upper plate and the lower plate was uniaxially stretched in the MD direction and had a front retardation value (RO) of 110 nm at a light source of 589 nm and a refractive index ratio (NZ) of -3 Modified PS (polymethylmethacrylate) film.

FIG. 9 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  8: VA mode

Each first protective film of the upper plate and the lower plate was uniaxially stretched in the MD direction and had a front retardation value (RO) of 250 nm at a light source of 589 nm and a refractive index ratio (NZ) of -1 Modified PS (polymethylmethacrylate) film.

FIG. 10 shows that rainbow stains were not generated at all as a result of applying a voltage to the liquid crystal cell of the liquid crystal display device and calculating rainbow stains in all directions.

Example  9: IPS mode

The first and second protective films of the upper plate and the lower plate were uniaxially stretched in the MD direction on a 42-inch IPS mode liquid crystal cell, and the front retardation value (RO) at the light source of 589 nm was 250 Nm and a refractive index ratio (NZ) of 1 were laminated.

FIG. 11 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate iridescent blobs in all directions, and it was confirmed that iridescent irregularities did not occur at all.

Example  10: IPS mode (Only the second protective film is used)

The second protective films of the upper and lower plates were uniaxially stretched in the MD direction and had a front retardation value (RO) of 250 nm at a light source of 589 nm and a refractive index ratio (NZ) of 0 Modified polystyrene (PS) films were laminated.

Each first protective film of the upper plate and the lower plate was laminated with NRT (Japan), which is a TAC isotropic film.

FIG. 12 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  11: IPS mode (Only the second protective film is used)

Each of the second protective films of the upper and lower plates was uniaxially stretched in the MD direction and had a front retardation value (RO) of 150 nm at a light source of 589 nm and a refractive index ratio (NZ) of 1 A polyethylene terephthalate (PET) film was laminated.

Each first protective film of the upper plate and the lower plate was laminated with NRT (Japan), which is a TAC isotropic film.

FIG. 13 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  12: IPS mode

The first and second protective films of the upper plate and the lower plate were uniaxially stretched in the MD direction and had a front retardation value (RO) of 150 nm at a light source of 589 nm, a refractive index ratio (NZ) 0 &lt; / RTI &gt;

FIG. 14 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it can be confirmed that rainbow stains did not occur at all.

Example  13: IPS mode

The first and second protective films of the upper plate and the lower plate were uniaxially stretched in the MD direction and had a front retardation value (RO) of 200 nm at a light source of 589 nm, a refractive index ratio (NZ) -2 &lt; / RTI &gt; denatured polystyrene (PS) film.

FIG. 15 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate iridescent blobs in all directions, and it was confirmed that iridescent irregularities did not occur at all.

Example  14: IPS mode

The first and second protective films of the upper plate and the lower plate were uniaxially stretched in the MD direction and had a front retardation value (RO) of 290 nm at a light source of 589 nm, a refractive index ratio (NZ) 0.0 &gt; (PS) &lt; / RTI &gt;

FIG. 16 is a result of applying a voltage to the liquid crystal cell of the liquid crystal display device to calculate rainbow stains in all directions, and it was confirmed that rainbow stains did not occur at all.

Example  15: IPS mode

The first and second protective films of the upper plate and the lower plate were uniaxially stretched in the MD direction and had a front retardation value (RO) of 250 nm at a light source of 589 nm, a refractive index ratio (NZ) (Polyethylene terephthalate (PET) film having a thickness of 2 mm was laminated.

FIG. 17 shows that rainbow stains were not generated at all as a result of applying a voltage to the liquid crystal cell of the liquid crystal display device and calculating rainbow stains in all directions.

Comparative Example  One

Each first protective film of the upper and lower plates was uniaxially stretched in the TD direction and had a front retardation value (RO) of 2000 nm and a refractive index ratio (NZ) of 1.9 at a light source of 589 nm .

FIG. 18 shows that iridescence spots are generated as a result of applying a voltage to the liquid crystal cell of the liquid crystal display device and calculating rainbow stains in all directions.

Comparative Example  2

The first protective film of each of the upper and lower plates was biaxially stretched and laminated to have a front retardation value (RO) of 2000 nm and a refractive index ratio (NZ) of 3 at a light source of 589 nm .

FIG. 19 shows that iridescent irregularities were generated in all directions by applying a voltage to the liquid crystal cell of the liquid crystal display device.

Claims (11)

The first protective film, the polarizer, the second protective film and the pressure-sensitive adhesive layer.
Wherein the at least one protective film is uniaxially stretched in the machine direction (MD), the front retardation value (RO) is greater than 100 nm and less than 300 nm,
Wherein the following formula (1) is satisfied:
[Equation 1]

(Where RO is the front retardation value and NZ is the refractive index ratio).
The polarizer of claim 1, wherein the NZ is NZ > 1.
The polarizing plate according to claim 1, wherein the NZ is NZ <
The polarizer of claim 1, wherein the at least one protective film is a first protective film.
The polarizer of claim 1, wherein the at least one protective film is a second protective film.
The polarizer of claim 1, wherein the at least one protective film is a first protective film and the second protective film.
The method according to claim 5 or 6, wherein the second protective film is formed of at least one selected from the group consisting of a cycloolefin polymer (COP), a cycloolefin copolymer (COC), a polyethylene terephthalate (PET), a polypropylene (PP), a polystyrene (PS), a polycarbonate ), Polysulfone (PSF), and polymethylmethacrylate (PMMA).
The method of claim 4 or 6, wherein the first protective film is formed of at least one selected from the group consisting of a cycloolefin polymer (COP), a cycloolefin copolymer (COC), a polyethylene terephthalate (PET), a polypropylene (PP), a polystyrene (PS), a polycarbonate ), Polysulfone (PSF), and polymethylmethacrylate (PMMA).
The polarizing plate according to claim 1, wherein the first protective film comprises a surface treatment layer on a side opposite to a side bonded to the polarizer.
A liquid crystal display device comprising the polarizer of any one of claims 1 to 6.
11. The liquid crystal display device according to claim 10, wherein the liquid crystal display device includes a polarizing backlight.

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