KR20200035477A - Liquid crystal display device, polarizing plates, and polarizer protection film - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device in which occurrence of rainbow unevenness is suppressed when an alignment polyester film is used as both polarizer protective films of a pair of polarizing plates.
In order to solve the above problem, the liquid crystal display device of the present invention is a liquid crystal display device having a backlight light source, two polarizing plates and a liquid crystal cell disposed between the two polarizing plates, wherein the backlight light source has a white light source having a continuous emission spectrum. Wherein, the polarizing plate is a configuration in which a polarizer protective film is laminated on both sides of a polarizer, at least one of the polarizer protective film of the polarizing plate disposed on the incident light side, and at least one of the polarizer protective film of the polarizing plate disposed on the exit light side is 4,000 ~ It is characterized by being an oriented polyester film having a retardation of 30,000 nm and an Nz coefficient of 1.7 or less.

Description

Liquid crystal display device, polarizing plate, and polarizer protection film

The present invention relates to a liquid crystal display device. Specifically, the present invention relates to a liquid crystal display in which the occurrence of rainbow stains is improved.

A polarizing plate used in a liquid crystal display (LCD) is a structure in which a polarizer in which iodine is dyed in polyvinyl alcohol (PVA) or the like is sandwiched between two polarizer protective films. As a polarizer protective film, triacetyl cellulose ( TAC) film is used. Recently, with the thinning of the LCD, thinning of the polarizing plate is required. However, for this reason, when the thickness of the TAC film used as a protective film is made thin, it is impossible to obtain sufficient mechanical strength, and a problem arises that moisture permeability deteriorates. In addition, TAC film is very expensive, and an inexpensive alternative material is strongly required.

Accordingly, it has been proposed to use a polyester film instead of the TAC film to maintain high durability even if the thickness is thin as a polarizer protective film for thinning the polarizing plate (Patent Documents 1 to 3).

The polyester film has superior durability compared to the TAC film, but, unlike the TAC film, has birefringence, so that when it is used as a polarizer protective film, there is a problem that the image quality deteriorates due to optical deformation. That is, the polyester film having birefringence has a predetermined optical anisotropy (retardation), and when used as a polarizer protective film, when observed in the oblique direction, a rainbow-shaped color stain occurs and the image quality deteriorates. For this reason, in Patent Documents 1 to 3, measures are taken to reduce retardation by using a copolymerized polyester as polyester. However, even in this case, it was impossible to completely remove the rainbow-colored stain.

Japanese Patent Publication No. 2002-116320 Japanese Patent Publication No. 2004-219620 Japanese Patent Publication No. 2004-205773 WO 2011-162198

The present inventors have found that as a means for solving the above problem, a white light emitting diode is used as a backlight light source and an oriented polyester film having a constant retardation is used as a polarizer protective film (Patent Document 4). However, the inventors have repeatedly studied the liquid crystal display device having such a structure, and even when the improved liquid crystal display device uses a polyester film as a polarizer protective film on both sides of a pair of polarizers, the angle is observed when viewed from an oblique direction. Therefore, we discovered the existence of a new task that rainbow stains still occur. Accordingly, the main object of the present invention is to suppress the occurrence of rainbow stains when an alignment polyester film is used as a polarizer protective film for both polarizers of a pair of polarizing plates of a liquid crystal display device.

As a result of examining the above problems day and night, the present inventors control liquid crystal display devices by controlling retardation of the oriented polyester film used as a polarizer protective film and Nz coefficients represented by │ny-nz│ / │ny-nx│ It has been found that the occurrence of rainbow unevenness when a polyester film is used as a polarizer protective film for both polarizers of a pair can be effectively suppressed. The present invention is a completed invention as a result of repeated research and improvement based on these findings.

Representative present invention is as follows.

Item 1.

A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates,

The backlight light source is a white light source having a continuous emission spectrum,

The polarizing plate is a configuration in which a polarizer protective film is laminated on both sides of a polarizer,

At least one of the polarizer protective film of the polarizing plate disposed on the incident light side, and at least one of the polarizer protective film of the polarizing plate disposed on the exit light side is an oriented polyester film having a retardation of 4,000 to 30,000 nm and an Nz coefficient of 1.70 or less

Liquid crystal display device.

Item 2.

The incident light side polarizer protective film of the polarizing plate disposed on the incident light side and the exit light side polarizer protective film of the polarizing plate disposed on the exit light side are oriented polyester films having retardation of 4,000 to 30,000 nm and Nz coefficient of 1.7 or less The liquid crystal display device according to claim 1.

Section 3.

The liquid crystal display device according to claim 1 or 2, wherein the orientation polyester film has a plane orientation of 0.13 or less.

Item 4.

The liquid crystal display device according to any one of claims 1 to 3, wherein the white light source having the continuous emission spectrum is a white light emitting diode.

Clause 5.

Consisting of laminating a polarizer protective film on both sides of the polarizer,

A polarizing plate for a liquid crystal display device having a white light source having a continuous emission spectrum as a backlight light source, wherein the polarizer protective film on at least one side is an oriented polyester film having a retardation of 4,000 to 30,000 nm and an Nz coefficient of 1.7 or less.

Clause 6.

A polarizing plate for a liquid crystal display device having a white light source having a continuous emission spectrum according to claim 5 having a plane orientation of 0.13 or less as the backlight light source.

Section 7.

A polarizer protective film for a liquid crystal display device comprising a white light source having a continuous emission spectrum as a backlight light source, which consists of an oriented polyester film having a retardation of 4,000 to 30,000 nm and an Nz coefficient of 1.7 or less.

Item 8.

A polarizer protective film for a liquid crystal display device comprising a white light source having a continuous emission spectrum according to claim 7 as a backlight light source, wherein the orientation polyester film has a plane orientation of 0.13 or less.

Item 9.

A polarizer protective film for a liquid crystal display device in which the white light source having a continuous emission spectrum according to claim 7 or 8, wherein the oriented polyester film has an easily adhesive layer, is a backlight light source.

Item 10.

The oriented polyester film is composed of at least three layers, contains an ultraviolet absorber in a layer other than the outermost layer, and has a light transmittance of 380 nm of 20% or less, according to any one of claims 7 to 9, A polarizer protective film for a liquid crystal display device using a white light source having an emission spectrum as a backlight light source.

The liquid crystal display device of the present invention has excellent visibility because generation of rainbow stains is suppressed. In addition, the liquid crystal display device of the present invention makes it possible to use an oriented polyester film as a polarizer protective film for both polarizers of a pair of polarizing plates without the occurrence of rainbow stains. Therefore, the present invention makes it possible to further reduce the thickness while maintaining sufficient mechanical strength of the liquid crystal display device, and further to reduce the manufacturing cost. In addition, the polarizing plate and the polarizer protective film of the present invention enable the production of the liquid crystal display device of the present invention.

1. Liquid crystal display

In general, a liquid crystal display device is composed of a rear module, a liquid crystal cell, and a front module in order from the side facing the backlight light source to the side displaying the image (viewing side or emitting light side). The rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the liquid crystal cell side surface, and a polarizing plate disposed on the opposite side. Here, the polarizing plate is disposed on the side opposite to the backlight light source in the case of the rear module, and on the side displaying the image (viewing side or outgoing light side) in the case of the front module.

2. Backlight source

The liquid crystal display device of the present invention includes at least a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates as a constituent member. The liquid crystal display device of the present invention may have other constituent members than these, for example, a color filter, a lens film, a diffusion sheet, and an antireflection film.

The configuration of the backlight may be either an edge light system using a light guide plate, a reflector, or the like, or a direct type system. In the present invention, it is preferable to use a white light source having a continuous broad emission spectrum as a backlight light source for a liquid crystal display device. Here, the continuous broad emission spectrum means an emission spectrum in which a wavelength at which light intensity is zero does not exist in a wavelength region of at least 450 nm to 650 nm, preferably a visible light region. As a white light source having such a continuous broad emission spectrum, for example, a white LED may be mentioned, but is not limited thereto.

The white LED usable in the present invention includes a phosphor type, that is, a blue light using a compound semiconductor, or an element emitting white by combining a light emitting diode and a phosphor emitting ultraviolet light, an organic light emitting diode (OLED), or the like. Is included. Examples of the phosphor include yttrium-aluminum-garnet-based yellow phosphors, terbium-aluminum-garnet-based yellow phosphors, and the like. Among the white LEDs, a white light emitting diode composed of a light emitting device combining a blue light emitting diode using a compound semiconductor and a yttrium-aluminum-garnet-based yellow phosphor has a continuous and broad emission spectrum, and at the same time has excellent light emission efficiency. It is suitable as a backlight light source. Since the white LED has low power consumption, the liquid crystal display device of the present invention using it also contributes to energy saving.

Fluorescent tubes, such as cold cathode tubes and hot cathode tubes, which are widely used as backlight sources in the past, have a discontinuous emission spectrum in which the emission spectrum has a peak at a specific wavelength. Therefore, it is difficult to obtain the desired effect of the present invention, and therefore, it is not preferable as a light source for the liquid crystal display device of the present invention.

3. Polarizer protective film

The polarizing plate has a configuration in which two polarizer protective films are laminated on both sides of a polarizer in which iodine is dyed in PVA or the like. The polarizing plate used in the present invention uses an oriented polyester film that satisfies the properties of Nz coefficient represented by a specific range of retardation and │ny-nz│ / │ny-nx│ on at least one side of the two polarizer protective films. do.

3-1. Retardation

It is preferable that the oriented polyester film used for the polarizer protective film used in the present invention has a retardation of 4,000 to 30,000 nm. This is because, when the retardation is less than 4,000 nm, it is impossible to ensure good visibility at all times because the liquid crystal display device has an interference color when observed in the oblique direction. The preferred retardation of the oriented polyester film is 4500 nm or more, next preferably 5,000 nm or more, more preferably 6,000 nm or more, even more preferably 8,000 nm or more, even more preferably 10,000 nm or more.

The upper limit of the retardation of the oriented polyester film is 30,000 nm. This is because even when an oriented polyester film having more retardation is used, an additional improvement effect of visibility is not substantially obtained, and as the retardation increases, the film thickness is also significantly thickened, resulting in deterioration in handling properties as an industrial material.

The retardation value of the oriented polyester film can be obtained by measuring the refractive index and thickness in the biaxial direction according to a known method. It is also possible to measure using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Measurement Instruments Co., Ltd.), for example.

As shown in patent document 4, when using an oriented polyester film as a polarizer protective film of only one of a pair of polarizing plates, the retardation of an oriented polyester film is controlled in the range of 3,000-30,000 nm, and as a light source The occurrence of rainbow stains is suppressed by employing a white light source having a continuous and broad emission spectrum. The principle is considered as follows.

That is, when a birefringence is provided on one side of the polarizer, when the oriented polyester film is disposed, linearly polarized light emitted from the polarizer is disturbed when passing through the polyester film. In addition, the transmitted light exhibits an interference color unique to retardation, which is the product of the birefringence and thickness of the polyester film. Therefore, when a light source having a discontinuous emission spectrum such as a cold cathode tube or a hot cathode tube is used as a light source, different transmitted light intensities are exhibited depending on the wavelength, resulting in a rainbow-colored stain.

On the other hand, when light having a continuous and broad emission spectrum in a wavelength region of at least 450 nm to 650 nm, preferably a visible light region, passes through the birefringent, the interference color spectrum becomes an envelope shape. Thus, by controlling the retardation of the polyester film, it is possible to obtain a spectrum similar to the emission spectrum of the light source. As described above, it is considered that the color of the light emission spectrum of the light source and the envelope shape of the interference color spectrum due to the transmitted light transmitted through the birefringent are shaped like a rainbow, so that a rainbow-like color stain is not generated, and thus the visibility is considerably improved.

However, as described above, when the oriented polyester film was used as the polarizer protective film on both sides of the pair of polarizing plates, the occurrence of rainbow stains was still sometimes observed. The present invention enables the suppression of such rainbow spotting, but the principle is still not fully elucidated.

3-2. Nz coefficient

It is preferable that the Nz coefficient represented by │ny-nz│ / │ny-nx│ of the oriented polyester film used for the polarizer protective film is 1.7 or less. The Nz coefficient can be determined as follows. The orientation axis direction of the film is obtained using a molecular orientation system (MOA-6004 molecular orientation system manufactured by Oji Scientific Instruments Co., Ltd.), and the refractive index of two axes in the direction perpendicular to the orientation axis direction (ny, nx, but ny> nx ) And the refractive index (nz) in the thickness direction are determined by an Abbe refractometer (manufactured by Atago, NAR-4T, measurement wavelength 589 nm). The Nz coefficient can be obtained by substituting the obtained nx, ny, and nz into the expression expressed by │ny-nz│ / │ny-nx│.

When the Nz coefficient of the oriented polyester film exceeds 1.7, rainbow stains may occur depending on the angle when the liquid crystal display is observed in the oblique direction. The Nz coefficient is more preferably 1.65 or less, and even more preferably 1.63 or less. The lower limit of the Nz coefficient is 1.2. This is because it is technically difficult to obtain a film of less than 1.2. In addition, in order to maintain the mechanical strength of the film, the lower limit of the Nz coefficient is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.45 or more.

3-3. Arrangement of polarizer protective film

In the liquid crystal display device of the present invention, the oriented polyester film having the specific retardation and Nz coefficient is used as both polarizer protective films of a pair of polarizing plates. The pair of polarizing plates means a combination of a polarizing plate disposed on the incident light side with respect to the liquid crystal and a polarizing plate disposed on the exit light side with respect to the liquid crystal. That is, the oriented polyester film is used for both polarizing plates of the polarizing plate on the incident light side and the polarizing plate on the exit light side. The oriented polyester film may be used as at least one of the two polarizer protective films constituting each polarizing plate, and may be used for both.

In one suitable embodiment, the oriented polyester film is used as an incident light side polarizer protective film of the incident light side polarizing plate, and is also used as an exit light side polarizer protective film of the incident light side polarizing plate. When the oriented polyester film is used on only one of the two polarizer protective films constituting the polarizing plate, an arbitrary polarizer protective film (for example, a TAC film, etc.) can be used on the other. When the alignment polyester film is employed as the polarizer protective film on the liquid crystal cell side of the polarizing plate disposed on the incident light side and the polarizer protective film on the liquid crystal cell side of the polarizing plate disposed on the exit light side, the polarization characteristics of the liquid crystal cell may change. It is preferable to use a polarizer protective film (for example, a TAC film, an acrylic film, a film without birefringence typified by a norbornene-based film) other than the oriented polyester film as the polarizer protective film at these positions.

3-4. Face orientation coefficient

In addition to controlling the retardation value and the Nz coefficient of the oriented polyester film within the above-mentioned specific range, by setting the surface orientation degree represented by (nx + ny) / 2-nz to be less than or equal to a specific value, the polarizer is protected on both sides of the pair of polarizing plates more reliably. Rainbow stains when a polyester film is used as the film can be completely eliminated. Here, the values of nx, ny, and nz are obtained in the same way as the Nz coefficient. The orientation degree of the oriented polyester film is preferably 0.13 or less, more preferably 0.125 or less, and even more preferably 0.12 or less. When the liquid crystal display device is observed in an oblique direction by setting the surface orientation degree to 0.13 or less, rainbow stains observed depending on the angle can be completely eliminated. The plane orientation degree is preferably 0.08 or more, and more preferably 0.10 or more. When the plane orientation degree is less than 0.08, the film thickness may fluctuate and the retardation value may become non-uniform in the film plane.

3-5. Retardation fee

The ratio (Re / Rth) of the retardation (Re) and the thickness direction retardation (Rth) of the oriented polyester film is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 0.6 or more. This is because the larger the ratio (Re / Rth) of the retardation and the thickness direction retardation, the more the birefringence action adds isotropy and the more difficult it is to generate rainbow-colored stains depending on the viewing angle. In the case of a complete uniaxial (uniaxially symmetrical) film, the ratio (Re / Rth) between the retardation and the thickness direction retardation is 2. However, as will be described later, the mechanical strength in the direction perpendicular to the orientation direction is remarkably reduced as it approaches the complete uniaxial (uniaxially symmetric) film.

Accordingly, the upper limit of the ratio (Re / Rth) of the retardation and the retardation in the thickness direction is preferably 1.2 or less, more preferably 1 or less. In order to completely suppress the occurrence of rainbow-colored stains according to the viewing angle, the ratio (Re / Rth) of the retardation and the retardation in the thickness direction does not need to be 2, and 1.2 or less is sufficient. In addition, even if the ratio is 1.0 or less, it is sufficiently possible to satisfy the viewing angle characteristics (180 degrees left and right, about 120 degrees up and down) required for the liquid crystal display.

3-6. Thickness deviation

In order to suppress the retardation fluctuation of the oriented polyester film, it is preferable that the film thickness variation is small. From this viewpoint, the thickness deviation of the oriented polyester film is preferably 5% or less, more preferably 4.5% or less, even more preferably 4% or less, and particularly preferably 3% or less.

3-7. thickness

The thickness of the oriented polyester film is not particularly limited as long as it does not interfere with the effects of the present invention, but is usually 15 to 300 μm, preferably 15 to 200 μm. When the film thickness is less than 15 µm, the anisotropy of the mechanical properties of the film becomes remarkable, and tearing or cracking may occur. The lower limit of the particularly preferred thickness is 25 μm. On the other hand, when the upper limit of the thickness of the polarizer protective film exceeds 300 μm, the thickness of the polarizing plate becomes too thick, which is not preferable. From the viewpoint of practicality as a polarizer protective film, the upper limit of the thickness is preferably 200 µm. The upper limit of a particularly preferable thickness is 100 µm, which is equivalent to that of a typical TAC film.

3-8. Polyester resin

The oriented polyester film used in the present invention can be obtained from any polyester resin. The type of the polyester resin is not particularly limited, and any polyester resin obtained by condensing a dicarboxylic acid and a diol can be used.

As a dicarboxylic acid component which can be used for manufacture of a polyester resin, for example, terephthalic acid, isophthalic acid, orthophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4- Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid, 1,3-cyclopentane Dicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, 3,3-di Ethyl succinic acid, glutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, azelaic acid, dimer acid, sebacic acid, suberic acid, dodecadi And carboxylic acids.

As a diol component which can be used for the production of a polyester resin, for example, ethylene glycol, propylene glycol, hexamethylene glycol, neopentyl glycol, 1,2-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, decamethylene glycol , 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) And sulfones.

The dicarboxylic acid component and the diol component constituting the polyester resin may be used alone or in combination of two or more. Suitable polyester resins constituting the polyester film include, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like, more preferably polyethylene terephthalate or polyethylene naphthalate. These may further include other copolymerization components. These resins are excellent in transparency and also have excellent thermal and mechanical properties, so that retardation can be easily controlled by stretching. Particularly, polyethylene terephthalate is the most suitable material because of its large intrinsic birefringence and large retardation can be obtained relatively easily even if the film is thin.

3-9. Light transmittance

The orientation polyester film preferably has a light transmittance of 20% or less at a wavelength of 380 nm from the viewpoint of suppressing deterioration of an optical functional dye such as an iodine dye contained in a polarizer. The light transmittance of 380 nm is more preferably 15% or less, even more preferably 10% or less, and particularly preferably 5% or less. When the light transmittance is 20% or less, deterioration of the optically functional dye by ultraviolet rays can be suppressed. The light transmittance is measured by a method perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).

The transmittance of the 380 nm wavelength of the oriented polyester film can be controlled to 20% or less by appropriately adjusting the type, concentration and thickness of the ultraviolet absorber to be blended. As the ultraviolet absorber used in the present invention, a known ultraviolet absorber can be appropriately selected and used. Specific examples of the ultraviolet absorber include organic ultraviolet absorbers and inorganic ultraviolet absorbers, and an organic ultraviolet absorber is preferred from the viewpoint of transparency.

Examples of the organic ultraviolet absorber include benzotriazole-based, benzophenone-based and cyclic imino-ester-based compounds, and combinations thereof, but are not particularly limited as long as they are within the range of absorbance specified by the present invention. However, from the viewpoint of durability, benzotriazole-based and cyclic iminoester-based are particularly preferred. When two or more types of ultraviolet absorbers are used in combination, since ultraviolet rays of respective wavelengths can be simultaneously absorbed, the ultraviolet absorption effect can be further improved.

Examples of benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers and acrylonitrile-based ultraviolet absorbers include 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotria Sol, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxypropyl ) Phenyl] -2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,4-di -tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (5-chloro (2H) -benzotriazol-2-yl) -4-methyl-6- (tert-butyl) phenol, 2,2'-methylenebis (4- (1,1,3,3) -Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol, etc. As a cyclic iminoester-based ultraviolet absorber, for example, 2,2 '-(1,4-phenylene ) Bis (4H-3,1-benzoxazinon-4-one), 2-methyl-3,1- Zoxazinone-4-one, 2-butyl-3,1-benzoxazinone-4-one, 2-phenyl-3,1-benzoxazinone-4-one, etc. These ultraviolet absorbers 1 You may use only 1 type and may use 2 or more types together.

In the case of blending the ultraviolet absorber with the oriented polyester film, it is preferable to add the ultraviolet absorber to the layers other than the outermost layer (ie, the intermediate layer) of the film with the multilayer structure of three or more layers.

3-10. Other ingredients

It is also a preferred aspect that the oriented polyester film contains various additives in a range that does not interfere with the effects of the present invention in addition to the ultraviolet absorber. Examples of the additives include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light resistance agents, flame retardants, heat stabilizers, antioxidants, antigelling agents, surfactants, and the like. In addition, it is preferable that the polyester film is substantially free of particles in order to exhibit high transparency. The term "substantially free of particles" means, for example, in the case of inorganic particles, when the inorganic element is quantified by fluorescence X-ray analysis, 50 ppm or less, preferably 10 ppm or less, particularly preferably detection limit or less It means the content to be.

4. This adhesive layer

In the present invention, in order to improve adhesiveness with a polarizer, it is preferable to have an easily adhesive layer having at least one kind of a polyester resin, a polyurethane resin or a polyacrylic resin as a main component on at least one side of an oriented polyester film. Here, the "main component" refers to a component of 50% by mass or more of the solid components constituting the easily adhesive layer. The coating liquid used for the formation of the easily-adhesive layer of the present invention is preferably an aqueous coating liquid containing at least one of water-soluble or water-dispersible copolymerized polyester resin, acrylic resin and polyurethane resin. Examples of these coating liquids are disclosed in Japanese Patent No. 35,627,271, Japanese Patent No. 3589232, Japanese Patent No.3589233, Japanese Patent No. 3900191, Japanese Patent No. 4150982, etc. Water-soluble or water-dispersible copolymer polyester resin solutions, acrylic resin solutions, polyurethane resin solutions, and the like.

This adhesive layer can be obtained by applying the coating solution to one or both sides of an unstretched film or a uniaxially stretched film in the longitudinal direction, drying at 100 to 150 ° C, and further stretching in the transverse direction. It is preferable to manage the coating amount of the final easily adhesive layer at 0.05 to 0.2 g / m 2. When the coating amount is less than 0.05 g / m 2, adhesiveness with the obtained polarizer may be insufficient. On the other hand, when the coating amount exceeds 0.2 g / m 2, the blocking resistance may decrease. When the easy-adhesive layer is provided on both sides of the polyester film, the coating amount of the double-sided easy-adhesive layer may be the same or different, and can be independently set within the above range.

It is preferable to add particles to this adhesive layer in order to impart an easy activity. It is preferable to use particles having an average particle diameter of 2 µm or less. When the average particle diameter of the particles exceeds 2 μm, the particles tend to fall off from the coating layer. Examples of the particles to be included in the adhesive layer include titanium oxide, barium sulfate, calcium carbonate, calcium sulfate, silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, and fluoride. And inorganic particles such as calcium and organic polymer particles such as styrene, acrylic, melamine, benzoguanamine, and silicone. These may be added to the self-adhesive layer alone, or two or more of them may be added in combination.

The coating liquid can be applied using a known method. For example, reverse roll coat method, gravure coat method, kiss coat method, roll brush method, spray coat method, air knife coat method, wire bar coat method, pipe doctor method and the like. These methods can be performed alone or in combination.

The average particle size of the particles can be measured by the following method. The particles are photographed with a scanning electron microscope (SEM) to measure the maximum diameter of 300 to 500 particles (distance between the two most distant points) at a magnification such that the size of one of the smallest particles is 2 to 5 mm. Let the average value be the average particle diameter.

The oriented polyester film may also be subjected to corona treatment, coating treatment, flame treatment, or the like in order to improve adhesion with a polarizer.

5. Functional layer

The polarizing plate used in the present invention is selected from the group consisting of various functional layers, that is, a hard coat layer, an anti-glare layer, an anti-reflection layer, a low-reflection layer, a low-reflection-prevention layer and an anti-reflective anti-glare layer for the purpose of preventing glare, suppressing glare, and suppressing scratches. It is also a preferred aspect that one or more functional layers are provided on the oriented polyester surface. When installing various functional layers, it is preferable that the oriented polyester film has an easily adhesive layer on its surface. At this time, from the viewpoint of suppressing interference due to reflected light, it is preferable to adjust the refractive index of the easily-adhesive layer to be near the rising average of the refractive index of the functional layer and the refractive index of the oriented polyester film. A known method can be used to adjust the refractive index of the adhesive layer, and for example, it can be easily adjusted by containing titanium, zirconium, or other metal species in the binder resin.

6. Manufacturing method of oriented polyester film

The oriented polyester film, which is the protective film of the present invention, can be produced according to a general method for producing a polyester film. For example, a non-oriented polyester molded by melting a polyester resin and extruding into a sheet shape is stretched in the longitudinal direction using a difference in the speed of the roll at a temperature above the glass transition temperature, and then stretched in the transverse direction by a tenter and heat treated. And a method of carrying out.

The oriented polyester film of the present invention may be a uniaxially stretched film or a biaxially stretched film, but when a biaxially stretched film is used as a polarizer protective film, rainbow color stains are not seen even when viewed from directly above the film surface, but observed in the oblique direction. When doing this, caution may be necessary because rainbow-colored stains may be observed.

This phenomenon is that the biaxially stretched film is composed of a refractive index ellipsoid having different refractive indices in the driving direction, the width direction, and the thickness direction, so that the retardation becomes zero (refractive index ellipsoid is seen as a circle) according to the light transmission direction inside the film. Because it exists. Therefore, when the liquid crystal display screen is observed in a specific direction in the inclined direction, there may be a point where the retardation becomes zero, and a rainbow color stain is concentrically generated around the point. In addition, when the angle from the top of the film surface (normal direction) to the position where the rainbow-shaped color stain is visible is θ, the angle θ becomes larger as the birefringence in the film surface increases, making it difficult to see the rainbow-colored color stain. In the case of the biaxially oriented film, the angle θ tends to be small, so the uniaxially oriented film tends to have a rainbow color stain, which is preferable.

However, in the case of a complete uniaxial (uniaxially symmetrical) film, it is not preferable because the mechanical strength in the direction perpendicular to the orientation direction is significantly reduced. It is preferable that the present invention has biaxiality (biaxial symmetry) in a range that does not substantially generate a rainbow color stain or a range that does not generate a rainbow color stain in a viewing angle range required for a liquid crystal display screen. This biaxial symmetry is obtained by producing an oriented polyester film under the following conditions.

The oriented polyester film having the above-mentioned specific retardation and Nz coefficient can be obtained by adjusting conditions (for example, stretching ratio, stretching temperature, film thickness, etc.) during film formation. For example, the higher the draw ratio, the lower the draw temperature, and the thicker the film, the easier it is to obtain high retardation. On the other hand, the lower the stretching ratio, the higher the stretching temperature, and the thinner the film, the easier it is to obtain low retardation.

As specific film forming conditions, for example, the longitudinal stretching temperature and the transverse stretching temperature are preferably 80 to 145 ° C, particularly preferably 90 to 140 ° C. The longitudinal stretching magnification is preferably 1.0 to 3.5 times, particularly preferably 1.0 to 3.0 times. Moreover, as for lateral stretch magnification, 2.5-6.0 times are preferable, Especially preferably, they are 3.0-5.5 times.

In order to control the retardation to the above-mentioned specific range, it is preferable to control the ratio of the longitudinal stretching ratio and the transverse stretching ratio. If the difference in the stretching ratio between the width and height is too small, it is difficult to increase the retardation, which is not preferable. It is also preferable to set the stretching temperature low to increase retardation. Subsequently, the heat treatment temperature is preferably 100 to 250 ° C, particularly preferably 180 to 245 ° C.

In order to set the Nz coefficient to the above-mentioned specific value, it is preferable to control the ratio between the longitudinal stretching ratio and the transverse stretching ratio, and it is most preferable to use a uniaxially stretched film. Further, in order to lower the Nz coefficient, it is also preferable to increase the molecular weight of the polymer and to add a copolymerization component to lower the crystallinity. Moreover, in order to control the Nz coefficient of a film to a specific range, it can be performed by setting the overall draw ratio and the draw temperature appropriately. For example, the lower the overall draw ratio and the higher the draw temperature, the lower the Nz coefficient can be obtained.

In order to set the plane orientation degree to the above-described specific value, it is preferable to control the overall draw ratio. If the total draw ratio is too high, it is not preferable because the degree of plane orientation becomes too high. In addition, controlling the stretching temperature is also preferable in reducing the plane orientation. By increasing the difference between the vertical stretching magnification and the transverse stretching magnification, setting the overall stretching magnification low, and setting the stretching temperature high, it becomes possible to make the Nz coefficient and the plane orientation less than a specific value.

Since the stretching temperature and the draw ratio greatly influence the thickness variation of the film, it is preferable to optimize the film forming conditions from the viewpoint of the thickness variation. In particular, in order to increase the retardation, if the longitudinal stretching magnification is lowered, the vertical thickness deviation may worsen. It is preferable to set the film-forming conditions at a position outside the range from the area where the vertical thickness deviation is extremely deteriorated in a specific range of the draw ratio.

Blending of the ultraviolet absorber to the oriented polyester film can be carried out by combining known methods. For example, the UV absorber dried using a kneading extruder and the polymer raw material are blended to prepare a masterbatch in advance, and may be blended by a method of mixing the predetermined masterbatch and the polymer raw material during film formation.

It is preferable that the concentration of the ultraviolet absorber in the masterbatch is 5-30% by mass in order to uniformly disperse the ultraviolet absorber and to economically mix it. It is preferable that a kneading extruder is used as a condition for producing the masterbatch, and the extrusion temperature is extruded over a period of 1 to 15 minutes at a temperature equal to or higher than the melting point of the polyester raw material and 290 ° C or lower. Above 290 ° C, the UV absorber has a large loss, and the viscosity of the masterbatch decreases. In the case of extrusion of 1 minute or less, uniform mixing of the ultraviolet absorber becomes difficult. At this time, a stabilizer, a color tone adjusting agent, and an antistatic agent may be added as necessary.

The UV absorber may be blended into the intermediate layer of the oriented polyester film having a multi-layer structure of three or more layers by the following method. After mixing and drying the pellet of polyester alone for the outer layer and the masterbatch containing the ultraviolet absorber for the intermediate layer and the pellet of the polyester at a predetermined ratio, and then feeding it to a known extruder for melt lamination, sheeting from a slit-shaped die Extruded into a shape and cooled and solidified on a casting roll to produce an unstretched film. That is, by using two or more extruders, three layers of manifolds or a confluence block (for example, a confluence block having a square confluence), a film layer constituting both outer layers and a film layer constituting an intermediate layer are laminated, and three are detained. The sheet of the layer is extruded and cooled with a casting roll to produce an unstretched film.

In order to remove foreign substances contained in the polyester of the raw material causing optical defects, it is preferable to perform high-precision filtration during melt extrusion in the manufacturing process of the oriented polyester film. The filter particle size (initial filtration efficiency of 95%) of the media used for high-precision filtration of the molten resin is preferably 15 µm or less. When the filter particle size of the filter medium exceeds 15 µm, the removal of foreign substances of 20 µm or more tends to be insufficient.

Example

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to the following Examples, and it is also possible to carry out by appropriately changing it within a range suitable for the spirit of the present invention, and they are all described It is included in the technical scope of the invention.

The evaluation method of physical properties in Examples is as follows.

(1) Retardation (Re)

Retardation is a parameter defined by the product of orthogonal biaxial refractive index (ΔNxy = │nx-ny│) and film thickness d (nm) (△ Nxy × d) on the film, and is a measure of optical isotropy and anisotropy. to be. The anisotropy (ΔNxy) of the biaxial refractive index was determined by the following method. The orientation axis direction of the film was determined using a molecular orientation system (MOA-6004 molecular orientation system manufactured by Oji Scientific Instruments Co., Ltd.), and a rectangle of 4 cm × 2 cm was cut out so that the orientation axis direction was a long side, and the sample was measured. Did. The refractive index (nx, ny) of the biaxial axis orthogonal to this sample and the refractive index (Nz) in the thickness direction were measured using an Abbe refractometer (manufactured by Atago Corporation, NAR-4T, measuring wavelength 589 nm), and the refractive index of the biaxial axis The absolute value of the difference (│nx-ny│) was taken as the anisotropy (ΔNxy) of the refractive index. The thickness d (nm) of the film was measured using an electric micrometer (manufactured by FineLoop, Millitron 1245D), and the unit was converted to nm. Retardation (Re) was determined from the product of the anisotropy (ΔNxy) of the refractive index and the thickness d (nm) of the film (ΔNxy × d).

(2) Nz coefficient

The value obtained by │ny-nz│ / │ny-nx│ was taken as the Nz coefficient. However, the values of ny and nx were selected so that ny> nx.

(3) Planar orientation (△ P)

The value obtained by (nx + ny) / 2-nz was taken as the plane orientation degree (ΔP).

(4) Thickness direction retardation (Rth)

The thickness direction retardation is the average of the retardation obtained by multiplying the film thickness d by two birefringences ΔNxz (= │nx-nz│) and ΔNyz (= │ny-nz│) when viewed from the cross section in the film thickness direction. Is a parameter indicating Nx, ny, nz and film thickness d (nm) are obtained in the same manner as the retardation measurement, and the average values of (ΔNxz × d) and (△ Nyz × d) are calculated to obtain the thickness direction retardation (Rth). Did.

(5) Observing rainbow stains

A polyester film produced by a method described later is attached to one side of the polarizer made of PVA and iodine so that the polarization axis of the polarizer and the orientation main axis of the polyester film are perpendicular, and the TAC film (Fuji film ( Co., Ltd., 80 µm thick) was attached to prepare a polarizing plate. The obtained polarizing plate was placed on both sides with a liquid crystal interposed therebetween, so that each polarizing plate was placed under the cross nicol condition to produce a liquid crystal display device. Each polarizing plate was arranged such that the polyester film was on the opposite side (distant position) from the liquid crystal. As a light source of the liquid crystal display device, a white LED composed of a light emitting device combining a blue light emitting diode and a yttrium aluminum aluminum garnet-based yellow phosphor was used as a light source (Nichia Chemical, NSPW500CS). The presence or absence of rainbow stains was determined as follows by observing with the naked eye from the front and inclined directions of the liquid crystal display device.

A: There is no occurrence of rainbow stains in any direction.

A ': When observed in the oblique direction, very pale rainbow stains are observed depending on the angle.

B: When observed from the oblique direction, pale rainbow stains are observed depending on the angle.

C: Rainbow stain was observed when observed from the inclined direction.

D: Rainbow stains were observed when observed from the front and inclined directions.

(6) Tear strength

The tear strength of each film was measured according to JIS P-8116 using an Elmendorf tear tester manufactured by Toyo Seisakusho. The tearing direction was performed to be parallel to the orientation of the main axis of the film, and was determined as follows. In addition, the measurement of the orientation main axis direction was measured with the molecular orientation system (Original Measuring Instruments Co., Ltd. product, MOA-6004 type molecular orientation system).

○: Tear strength of 50 mN or more

×: Tear strength is less than 50 mN

(Production Example 1-Polyester A)

When the esterification reaction tube was heated to reach 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were added while stirring, 0.017 parts by mass of antimony trioxide, 0.064 parts by mass of magnesium acetate tetrahydrate, and 0.16 parts by mass of triethylamine Was added. Subsequently, the pressure was elevated to carry out a pressure esterification reaction under conditions of a gauge pressure of 0.34 MPa and 240 ° C, and then the esterification reaction tube was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. The temperature was further increased to 260 ° C. over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Subsequently, dispersion treatment was performed with a high-pressure disperser after 15 minutes, and the esterified reaction product obtained after 15 minutes was transferred to a polycondensation reaction tube, and polycondensation reaction was carried out under reduced pressure at 280 ° C.

After completion of the polycondensation reaction, 95% cut diameter is filtered through a Naslon filter having a diameter of 5 μm, extruded from the nozzle into a strand shape, and cooled using cooling water that has been previously filtered (hole size: 1 μm or less), Solidified and cut into pellets. The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62 dl / g, and substantially no inert particles and internal precipitated particles were contained. (Hereinafter, abbreviated as PET (A).)

(Production Example 2-polyester B)

10 parts by mass of the dried ultraviolet absorbent (2,2 '-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), PET (A) containing no particles (high viscosity A 0.62 dl / g) 90 parts by mass were mixed, and a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (hereinafter abbreviated as PET (B)).

(Production Example 3-Preparation of adhesive-modified coating liquid)

Transesterification and polycondensation reactions are carried out in a conventional manner to prepare 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 8 mol of 5-sulfonatoisoisophthalate as dicarboxylic acid components (relative to all dicarboxylic acid components). %, A copolymerizable polyester resin containing a water-dispersible sulfonic acid metal base having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a glycol component (relative to the entire glycol component). Subsequently, 51.4 parts by mass of water, 38 parts by mass of isopropyl alcohol, 5 parts by mass of n-butyl cellosolve, and 0.06 parts by mass of a nonionic surfactant were mixed and stirred with heating to reach 77 ° C., and the water-dispersible sulfonic acid metal base was contained. After 5 parts by weight of the copolymerized polyester resin was added and stirring was continued until the resin mass disappeared, the resin aqueous dispersion was cooled to room temperature to obtain a uniform water-dispersible copolymerizable polyester resin solution having a solid content concentration of 5.0 mass%. In addition, after dispersing 3 parts by mass of aggregated silica particles (Filixia Co., Ltd., Silisia 310) in 50 parts by mass of water, 0.54 parts of water dispersion of Silisia 310 in 99.46 parts by mass of the water-dispersible copolymer polyester resin solution. Mass parts were added, and 20 mass parts of water was added while stirring to obtain an adhesive-modified coating solution.

(Polarizer protective film 1)

90 parts by mass of PET (A) resin pellets containing no particles and 10 parts by mass of PET (B) resin pellets containing ultraviolet absorbers as a raw material for the base film intermediate layer were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours, followed by an extruder. 2 [for intermediate layer (for II layer)], and PET (A) was dried in a conventional manner, and then supplied to extruder 1 (for outer layer (I layer) and outer layer (III layer)), respectively, and dissolved at 285 ° C. . Each of these two polymers was filtered with a filter medium of a stainless sintered body (nominal filtration accuracy of 10 µm particles, 95% cut), laminated into two types of three-layer confluence blocks, extruded into sheet form from custody, and then subjected to electrostatic application casting. By winding it on a casting drum having a surface temperature of 30 ° C. to cool and solidify it, an unstretched film was produced. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thicknesses of the I, II, and III layers was 10:80:10.

Subsequently, the adhesive-modified coating solution was applied to both sides of this unstretched PET film by a reverse roll method so that the applied amount after drying was 0.08 g / m 2, and then dried at 80 ° C. for 20 seconds.

The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and the end of the film was gripped with a clip and guided to a hot air zone at a temperature of 125 ° C, and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction at a temperature of 225 ° C. for 30 seconds, and further subjected to 3% relaxation treatment in the width direction, a uniaxially oriented PET film having a film thickness of about 50 μm was obtained.

(Polarizer protective film 2)

By changing the thickness of the unstretched film, a uniaxially oriented PET film was obtained in the same manner as the polarizer protective film 1 except that the thickness was about 100 µm.

(Polarizer protective film 3)

The unstretched film produced by the same method as the polarizer protective film 1 was heated to 105 ° C using a heated roll group and an infrared heater, and then stretched 1.5 times in the running direction with a roll group with a main speed difference, and then the polarizer protective film 1 It was stretched 4.0 times in the width direction in the same manner as to obtain a biaxially oriented PET film having a film thickness of about 50 μm.

(Polarizer protective film 4)

Stretched 2.0 times in the driving direction and 4.0 times in the width direction in the same manner as the polarizer protective film 3 to obtain a biaxially oriented PET film having a film thickness of about 50 μm.

(Polarizer protective film 5)

In the same manner as the polarizer protective film 1, a uniaxially oriented PET film having a film thickness of 50 µm was obtained without using a PET resin (B) containing an ultraviolet absorber in the intermediate layer.

(Polarizer protective film 6)

In the same manner as the polarizer protective film 3, 4.0 times in the running direction and 1.0 times in the width direction were stretched to obtain a uniaxially oriented PET film having a film thickness of about 100 μm.

(Polarizer protective film 7)

Stretched 1.0 times in the driving direction and 3.5 times in the width direction in the same manner as in the polarizer protective film 1 to obtain a uniaxially oriented PET film having a film thickness of about 75 μm.

(Polarizer protective film 8)

A uniaxially oriented PET film having a thickness of about 100 µm was obtained by changing the thickness of the unstretched film using the same method as for the polarizer protective film 1, with a lateral stretch magnification of 3.8 times and a stretching temperature of 135 ° C.

(Polarizer protective film 9)

A uniaxially oriented PET film having a thickness of about 50 µm was obtained by using the same method as for the polarizer protective film 1 with a lateral stretch magnification of 3.8 and a stretching temperature of 135 ° C.

(Polarizer protective film 10)

A uniaxially oriented PET film having a thickness of 50 µm was obtained by using a method similar to that of the polarizer protective film 1 with a lateral stretch magnification of 3.8 times.

(Polarizer protective film 11)

A uniaxially oriented PET film having a thickness of about 50 µm was obtained by using the same method as the polarizer protective film 1 with a lateral stretch magnification of 4.2 times and a stretching temperature of 135 ° C.

(Polarizer protective film 12)

A uniaxially oriented PET film having a thickness of 38 µm was obtained by changing the thickness of the unstretched film and changing the transverse magnification to 3.8 times using the same method as for the polarizer protective film 1.

(Polarizer protective film 13)

A uniaxially oriented PET film having a thickness of 38 µm was obtained by changing the thickness of the unstretched film using the same method as for the polarizer protective film 1.

(Polarizer protective film 14)

Stretched 1.8 times in the driving direction and 2.0 times in the width direction in the same manner as the polarizer protective film 3 to obtain a biaxially oriented PET film having a film thickness of about 275 μm.

(Polarizer protective film 15)

Stretched 3.6 times in the running direction and 4.0 times in the width direction in the same manner as the polarizer protective film 3 to obtain a biaxially oriented PET film having a film thickness of about 38 μm.

(Polarizer protective film 16)

A uniaxially oriented PET film having a thickness of about 10 μm was obtained by changing the thickness of the unstretched film using the same method as for the polarizer protective film 1.

Table 1 below shows the results of measuring rainbow spotting and tearing strength for the liquid crystal display device manufactured as described above using the polarizer protective films 1 to 17.

In Table 1, the polarizer protective film No. 7 * shows a case where a polarizer protective film 7 is used as a polarizer protective film and an organic light emitting diode (OLED) is used as a light source. In addition, in Table 1, the polarizer protective film No. 7 ** shows the case where the polarizer protective film 7 was used as a polarizer protective film, and the cold cathode tube was used as a light source. In Table 1, the polarizer protective film No. 1 * uses the polarizer protective film 1 as the exit light side polarizer protective film of the exit light side polarizer, and the incident light side polarizer protection film of the exit light side polarizer and both sides polarizer protection film of the incident light side polarizer The TAC film is used.

From the results shown in Table 1, it was shown that the occurrence of rainbow stain was significantly suppressed when the retardation of the oriented polyester film was 4,000 or more and the Nz coefficient was 1.7 or less. Moreover, it was shown that it is possible to suppress the occurrence of rainbow stain more effectively by controlling the degree of plane orientation of the oriented polyester film to 0.13 or less in addition to these conditions.

By using the liquid crystal display device of the present invention, a polarizing plate, and a polarizer protective film, it becomes possible to contribute to thinning and lowering the cost of the LCD without lowering visibility due to rainbow-colored color stains. Therefore, the industrial applicability of the present invention is extremely high.

Claims (3)

A liquid crystal display device having a backlight light source, two polarizing plates, and a liquid crystal cell disposed between the two polarizing plates,
The incident light side polarizer protective film of the polarizing plate disposed on the incident light side and the exit light side polarizer protective film of the polarizing plate disposed on the exit light side are retardation of 4,000 to 30,000 nm, a plane orientation degree of 0.13 or less, and an Nz coefficient of 1.7 or less Which is an oriented polyester film having
Liquid crystal display device (however, the backlight light source is a cold cathode tube, a liquid crystal display having a thickness of 75 µm, an in-plane retardation of 7,350 nm, and a thickness direction retardation (Rth) of 7,800 nm) Excluding display devices). A pair of polarizing plates laminated on both sides of the liquid crystal cell,
Each polarizing plate is laminated with an oriented polyester film having a retardation of 4,000 to 30,000 nm, a plane orientation degree of 0.13 or less, and an Nz coefficient of 1.7 or less on the polarizer,
A pair of polarizing plates for a liquid crystal display device (however, a pair of polarizing plates for a liquid crystal display device in which the backlight light source of the liquid crystal display device is a cold cathode tube, and the alignment polyester film has a thickness of 75 μm, an in-plane retardation of 7,350 nm, and 7,800 A pair of polarizing plates for a liquid crystal display device having a thickness direction retardation (Rth) of nm is excluded). According to claim 2,
A pair of polarizing plates for a liquid crystal display device in which the alignment polyester film is laminated on a position far from the liquid crystal cell of the polarizer.