TW201739802A - Liquid crystal display device - Google Patents

Abstract

Provided is a low-cost liquid crystal display device which has excellent visibility. A liquid crystal display device which sequentially comprises a backlight light source, a light source-side polarizing plate, a liquid crystal cell and a viewing-side polarizing plate in this order, and which is characterized in that: each of the light source-side polarizing plate and the viewing-side polarizing plate has a configuration wherein a polarizer protective film is laminated on at least one surface of a polarizer, while having an adhesive layer for bonding the polarizing plate with the liquid crystal cell; the viewing-side polarizing plate contains an ultraviolet absorbent; and the light source-side polarizing plate does not contain an ultraviolet absorbent.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device.

The polarizing plate used in a liquid crystal display device (LCD) is usually composed of two polarizer protective films sandwiching a polarizing plate coated with iodine such as polyvinyl alcohol (PVA). As a polarizer protective film, three-by-three is usually used. Cellulose (TAC) film. In recent years, with the thinning of LCDs, thinning of polarizing plates is required. However, if the thickness of the TAC film used as the protective film is reduced as a result, sufficient mechanical strength cannot be obtained and the moisture permeability is deteriorated. Also, TAC films are very expensive and strongly demand cheap alternative materials.

Therefore, in order to reduce the thickness of the polarizing plate, it is proposed to use a polyester film instead of the TAC film so that high durability can be maintained even if the thickness of the polarizer protective film is reduced (Patent Documents 1 to 3).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-116320

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-219620

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2004-205773

An object of the present invention is to provide a liquid crystal display device excellent in visibility with low cost.

The invention represented is as follows.

Item 1. A liquid crystal display device comprising a backlight source, a light source side polarizing plate, a liquid crystal cell, and a liquid crystal display device of a viewing side polarizing plate, wherein the light source side polarizing plate and the visual recognition side polarizing plate are respectively A polarizer protective film is laminated on at least one surface of the polarizer, and has an adhesive layer for bonding to the liquid crystal cell. The visual recognition side polarizing plate contains an ultraviolet absorber, and the light source side polarizing plate does not contain an ultraviolet absorber.

The liquid crystal display device according to item 1, wherein the polarizer protective film on the visual recognition side of the visual recognition side polarizing plate is a polyester film having a hysteresis of 3,000 to 30,000 nm, and the polyester film contains an ultraviolet absorber.

According to the present invention, a liquid crystal display device excellent in visibility can be provided at low cost.

[Formation of the Invention]

(The entire structure of the liquid crystal display device)

Generally, the liquid crystal panel is formed from the opposite side of the backlight source toward the side of the display image (visual identification side), and is sequentially composed of the rear module, the liquid crystal cell, and the front module. The rear module and the front module are generally composed of a transparent substrate, a transparent conductive film formed on the surface of the liquid crystal cell, and a polarizing plate disposed on the opposite side. Here, the polarizing plate is disposed on the opposite side of the backlight source in the rear module, and is disposed on the side of the display image (visual identification side) in the front module.

The liquid crystal display device of the present invention has at least a backlight source, a light source side polarizing plate, a liquid crystal cell, and a viewing side polarizing plate in this order. In addition, other members may be appropriately provided between the constituent members of the backlight source, the light source side polarizing plate, the liquid crystal cell, and the visibility side polarizing plate. For example, a color filter, a lens film, a diffusion sheet, an antireflection film, or the like can be suitably used.

(polarizer)

The two polarizing plates (the light source side polarizing plate and the visibility side polarizing plate) used in the liquid crystal display device of the present invention have at least one surface of a polarizing plate coated with iodine (PVA) or the like, and a polarizer protective film is bonded thereto. The composition. Preferably, the polarizer protective film is bonded to both surfaces of the polarizer, but a polarizer protective film may be laminated only on one surface of the polarizer. Preferably, the polarizer and the polarizer protective film are bonded together via an adhesive layer. From the viewpoint of adhesion, the polarizer protective film may have an easy adhesion layer for the purpose of surface modification. The polarizing plate has an adhesive layer for bonding to a liquid crystal cell. Further, the polarizing plate may have a mechanical layer such as a hard coat layer, an antiglare layer, an antireflection layer, and a low reflection layer on the surface thereof. That is, in the present invention The polarizing plate is a polarizer, a polarizer protective film laminated on at least one surface of the polarizer, and an adhesive layer for bonding to a liquid crystal cell as an essential constituent member, and has an adhesive layer, an easy adhesion layer or a function. The layer serves as an arbitrary constituent member.

The polarizing plate (visual identification side polarizing plate) disposed on the visual recognition side with the liquid crystal cell as a starting point preferably contains an ultraviolet absorber. In other words, at least one of the polarizer, the polarizer protective film, the adhesive layer, the adhesive layer, the easy-adhesion layer, and the functional layer as the constituent members of the visual recognition-side polarizing plate preferably contains an ultraviolet absorber. The ultraviolet absorber may be contained in a plurality of layers (members) of the constituent members of the side polarizing plate, but it is sufficient as long as it is contained in any layer (member).

Preferably, the polarizer protective film on the visibility side of the visual recognition side polarizing plate or the polarizer protective film on the light source side of the visual recognition side polarizing plate (including the optical compensation film (phase difference film)) preferably contains ultraviolet light absorption. The aspect of the agent. It is particularly preferable that the polarizer protective film on the visual recognition side of the side polarizing plate is visually recognized to contain an ultraviolet absorber. Further, from the viewpoint of being able to select a high-performance ultraviolet absorber at a lower cost, it is also preferable to visually recognize the polarizer protective film on the light source side of the side polarizing plate (including an optical compensation film (phase difference film)). Contains the appearance of a UV absorber.

As the entire visibility side polarizing plate, it is preferable to adjust the light transmittance at a wavelength of 380 nm to 10% or less. The light transmittance at a wavelength of 380 nm is more preferably 9% or less, particularly preferably 8% or less, and particularly preferably 5% or less. When the light transmittance is 10% or less, deterioration of the optical functional pigment due to ultraviolet rays or liquid in the liquid crystal cell can be suppressed. Deterioration of crystal molecules, etc. Further, the light transmittance is measured in a direction perpendicular to the plane of the polarizing plate, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).

The polarizing plate (light source side polarizing plate) disposed on the light source side with the liquid crystal cell as a starting point preferably has a lower ultraviolet absorbing agent content than the visual recognition side polarizing plate. It is particularly preferable that the light source side polarizing plate is completely free of the ultraviolet absorber.

As the entire light source side polarizing plate, the light transmittance at a wavelength of 380 nm is preferably more than 10%. The light transmittance at a wavelength of 380 nm is more preferably 11% or more, particularly preferably 12% or more, and particularly preferably 13% or more.

With such a configuration, the amount of the ultraviolet absorber used in the entire liquid crystal display device can be reduced, and the liquid crystal display device can be provided at low cost. Further, in a practical aspect, for example, when the backlight source is a light source including a blue light-emitting diode, since the light in the ultraviolet region is hardly contained, even if the light source-side polarizing plate does not have a UV absorber, substantially There is no problem such as deterioration of an optical functional dye such as an iodine dye or deterioration of liquid crystal molecules in a liquid crystal cell. Therefore, the liquid crystal display device is capable of suppressing deterioration of an optical functional dye such as an iodine dye or the like of an ultraviolet ray contained in external light incident from a visual recognition side surface, or deterioration of liquid crystal molecules in a liquid crystal cell. Yes, as long as it is only the visual recognition side polarizing plate containing an ultraviolet absorber, it can block ultraviolet rays.

Further, when the light source side polarizing plate contains the ultraviolet absorbing agent, the long-term heat from the backlight source depends on the type of the ultraviolet absorbing agent to be used, and the ultraviolet absorbing agent oozes out to the surface of the light source side polarizing plate. Visual recognition of liquid crystal display device Etc.) According to the present invention, the problem relating to the visibility of the liquid crystal display device described above can be eliminated by using the light source side polarizing plate without the ultraviolet absorber.

(UV absorber)

In order to make the light transmittance of the visible light polarizing plate at a wavelength of 380 nm 10% or less, it is preferable to appropriately adjust the type, concentration, and thickness of each layer of the ultraviolet absorber. The ultraviolet absorber used in the present invention can be used by a person skilled in the art, and is not particularly limited. Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and from the viewpoint of transparency, an organic ultraviolet absorber is preferred. The organic ultraviolet absorber is not particularly limited as long as it is a benzotriazole-based, a diphenylketone-based or a cyclic imido ester-based compound, and a combination thereof. However, from the viewpoint of durability, it is particularly preferably a benzotriazole-based or cyclic imido ester-based system. When two or more types of ultraviolet absorbers are used in combination, since ultraviolet rays of respective wavelengths can be simultaneously absorbed, the ultraviolet absorbing effect can be further improved.

Examples of the diphenylketone-based ultraviolet absorber, the benzotriazole-based ultraviolet absorber, and the acrylonitrile-based ultraviolet absorber include 2-[2'-hydroxy-5'-(methacryloxymethyl) Phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloxyethyl)phenyl]-2H-benzotriazole, 2-[2'- Hydroxy-5'-(methacryloxypropyl)phenyl]-2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxydiphenyl ketone, 2, 2',4,4'-tetrahydroxydiphenyl ketone, 2,4-di-t-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2-(2'-hydroxy- 3'-Tertibutyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(5-chloro(2H)-benzotriazol-2-yl)-4-methyl- 6-(t-butyl)phenol, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2- Phenyl, etc. Examples of the cyclic imido ester-based ultraviolet absorber include 2,2'-(1,4-phenylene)bis(4H-3,1-benzo). 4-keto), 2-methyl-3,1-benzo 4-ketone, 2-butyl-3,1-benzo 4-ketone, 2-phenyl-3,1-benzo 4-ketone and the like. However, it is not particularly limited by these.

(polarizer)

The polarizer can be suitably used by selecting any polarizer (polarizing film) used in the technical field. The polarizing plate which is a representative example is a dichroic material which is dyed with iodine or the like in a polyvinyl alcohol film or the like, but is not limited thereto, and a polarizer which is well known and can be developed in the future can be suitably selected.

For the PVA film, a commercially available product can be used. For example, "Kuraray Vinylon (KURARAY)", "Tohcello Vinylon (TOHCELLO)", and "Nikon Vinylon (Japan Synthetic Chemical Co., Ltd.)" can be used. Wait. Examples of the dichroic material include iodine, a diazo compound, and a polymethine dye.

The polarizer can be obtained by any method. For example, the PVA film can be uniaxially stretched in an aqueous solution of boric acid by being dyed with a dichroic material, and kept in an extended state, washed and dried. The stretching ratio of the uniaxial stretching is usually about 4 to 8 times, but there is no particular limitation. Other manufacturing conditions and the like can be appropriately set in accordance with well-known techniques.

(Polarizer protective film)

From the viewpoint of suppressing rainbow-like color spots, the polarizing plate used in the present invention is preferably a polyester film having at least one of the polarizer protective films having a hysteresis (Re, hysteresis in the film plane) of 3,000 to 30,000 nm. more The lower limit of the good hysteresis is 4,500 nm, and the lower limit is preferably 6000 nm, and the more preferable lower limit is 8000 nm. On the other hand, the upper limit of the hysteresis is preferably 30,000 nm.

Further, the hysteresis system can be obtained by measuring the refractive index and the thickness in the two-axis direction, and can also be obtained by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (Oji Scientific Instruments Co., Ltd.).

The arrangement of the polarizer protective film having the specific hysteresis in the liquid crystal display device is not particularly limited, and it is preferable that the polarizer of the light source side polarizing plate is used as a starting point, and the polarizer protective film on the light source side has the specific The polarizer protective film made of the retarded polyester film and/or the polarizer of the side polarizing plate is visually recognized, and the polarizer protective film on the visual recognition side is polarized by the polyester film having the specific retardation. Sheet protective film. A particularly preferable aspect is to use a polarizer for visually recognizing a side polarizing plate as a starting point, and a polarizing film protective film on the visual recognition side becomes a polyester film having the specific hysteresis. When the polyester film having the specific hysteresis is disposed at a position other than the above, the polarizing characteristics of the liquid crystal cell may be changed. Since it is not preferable to use a polyester film having the specific hysteresis where a polarizing property is required, it is preferably used only in such a limited position.

The polarizing plate used in the present invention is formed on at least one side of a polarizing plate coated with iodine such as polyvinyl alcohol (PVA), and is formed by laminating a polarizing film protective film. Preferably, any polarizing plate protective film has the above specific A polarizer protective film made of a retarded polyester film.

In another polarizer protective film, it is preferred to use, for example, a TAC film or an acrylic film. The olefinic film is a representative film having no birefringence. That is, it is preferred to have a polyester film/polarizer/(TAC film, acrylic film or drop) having a hysteresis of 3,000 to 30,000 nm. a polarizing plate comprising a laminate of an olefinic film/adhesive layer, and preferably a polyester film based on a polarizer of a light source side polarizing plate as a polarizing plate protective film on a light source side, or visually recognizing a side polarizing film The polarizer of the board is used as a starting point, and is disposed in such a manner as to visually recognize the polarizer protective film on the side.

The following is a particularly good description. Starting from the polarizer for visually recognizing the side polarizing plate, the polarizer protective film on the visual recognition side is preferably the aforementioned polyester film having a hysteresis of 3,000 to 30,000 nm, having an ultraviolet absorber in the film, and penetrating at a wavelength of 380 nm. The rate is below 20%. A polarizer protective film on the light source side when the polarizer of the side polarizing plate is used as a starting point, and a polarizer protective film on the visual recognition side when the polarizer of the light source side polarizing plate is used as a starting point, preferably a TAC film or acrylic Film or drop The olefinic film has a light transmittance of 60% or more at a wavelength of 380 nm. The polarizer of the light source side polarizing plate is used as a starting point, and the polarizer protective film on the light source side is preferably a polyester film having a hysteresis of 3,000 to 30,000 nm, and has a light transmittance of 70% or more at a wavelength of 380 nm.

(Polyester film)

The polyester used in the present invention may be polyethylene terephthalate or polyethylene terephthalate, and may contain other copolymerization components. These resins are excellent in transparency and excellent in thermal properties and mechanical properties, and can easily control hysteresis by stretching processing. In particular, polyethylene terephthalate is a most suitable material because it has a large intrinsic birefringence and is relatively easy to obtain a large hysteresis even if the thickness of the film is thin.

In addition, it is visually recognized for the purpose of suppressing deterioration of optical functional dyes such as iodine dyes or deterioration of liquid crystal molecules in liquid crystal cells. The polarizer of the side polarizer is a starting point, and the polarizer protective film made of the polyester film on the visual recognition side preferably has a light transmittance of 20% or less at a wavelength of 380 nm. The light transmittance at a wavelength of 380 nm is preferably 15% or less, more preferably 10% or less, and particularly preferably 5% or less. By reducing the light transmittance, it is possible to suppress deterioration of the optical functional pigment due to ultraviolet rays or deterioration of liquid crystal molecules in the liquid crystal cell. Further, the light transmittance is measured in a direction perpendicular to the plane of the film, and can be measured using a spectrophotometer (for example, Hitachi U-3500 type).

In order to make the light transmittance of the polyester film having a wavelength of 380 nm of 20% or less, it is preferred to appropriately adjust the type, concentration, and thickness of the ultraviolet absorber. The ultraviolet absorber used in the present invention is a well-known substance. Examples of the ultraviolet absorber include an organic ultraviolet absorber and an inorganic ultraviolet absorber, and from the viewpoint of transparency, an organic ultraviolet absorber is preferred. The organic ultraviolet absorber is exemplified by a benzotriazole type, a diphenyl ketone type, a cyclic imido ester type, and the like, and is not particularly limited. However, from the viewpoint of durability, a benzotriazole-based or cyclic imido ester is particularly preferred. When two or more types of ultraviolet absorbers are used in combination, the ultraviolet absorbing effect can be further improved by absorbing ultraviolet rays of respective wavelengths at the same time.

Examples of the diphenylketone-based ultraviolet absorber, the benzotriazole-based ultraviolet absorber, and the acrylonitrile-based ultraviolet absorber include 2-[2'-hydroxy-5'-(methacryloxymethyl) Phenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(methacryloxyethyl)phenyl]-2H-benzotriazole, 2-[2'- Hydroxy-5'-(methacryloxypropyl)phenyl]-2H-benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxydiphenyl ketone, 2, 2',4,4'-tetrahydroxydiphenyl ketone, 2,4-di-t-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2-(2'-hydroxy- 3'-Tertibutyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(5-chloro(2H)-benzotriazol-2-yl)-4-methyl- 6-(t-butyl)phenol, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2- Phenyl, etc. Examples of the cyclic imido ester-based ultraviolet absorber include 2,2'-(1,4-phenylene)bis(4H-3,1-benzo). 4-keto), 2-methyl-3,1-benzo 4-ketone, 2-butyl-3,1-benzo 4-ketone, 2-phenyl-3,1-benzo 4-ketone and the like. However, it is not particularly limited by these.

Further, in addition to the ultraviolet absorber, it is preferable that the catalyst contains various additives insofar as the effect of the present invention is not impaired. Examples of the additive include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, light stabilizers, flame retardants, heat stabilizers, antioxidants, and anti-gelation. Agent, surfactant, etc. Further, in order to achieve high transparency, it is also preferred that the polyester film contains substantially no particles. When the inorganic element is quantified by fluorescent X-ray analysis, for example, when it is inorganic particles, it means 50 ppm or less, preferably 10 ppm or less, and particularly preferably a content of less than the detection limit.

Further, the polyester film may be subjected to corona treatment, coating treatment, flame treatment or the like in order to improve the adhesion to the polarizer.

(Easy layer of polyester film)

In the present invention, in order to improve the adhesion to the polarizer, it is preferred to have a polyester resin, a polyurethane on at least one side of the polyester film. At least one of a resin or a polyacrylic resin is used as an easy-contact layer of a main component. Here, the "main component" means a component of 50% by mass or more of the solid components constituting the easy-adhesion layer. The coating liquid used for the formation of the easy-adhesion layer is preferably an aqueous coating liquid containing at least one of a water-soluble or water-dispersible copolymerized polyester resin, an acrylic resin, and a polyurethane resin. Examples of the coating liquids include, for example, Japanese Patent No. 3,567,927, Japanese Patent No. 3,589,232, Japanese Patent No. 3,589,233, Japanese Patent No. 3,900,191, and Japanese Patent No. 4,150,982. A water-soluble or water-dispersible copolymerized polyester resin solution, an acrylic resin solution, a polyurethane resin solution or the like disclosed in the above.

The easy-adhesion layer can be obtained by coating the coating liquid on one or both sides of the longitudinal uniaxially stretched film, drying at 100 to 150 ° C, and extending in the transverse direction. The coating amount of the final easy-adhesion layer is preferably managed at 0.05 to 0.20 g/m ² . When the coating amount is less than 0.05 g/m ² , the adhesion to the obtained polarizer may be insufficient. On the other hand, when the coating amount exceeds 0.20 g/m ² , the blocking resistance may be lowered. When an easy-adhesion layer is provided on both sides of the polyester film, the coating amounts of the easy-adhesion layers on both sides may be the same or different, and may be independently set within the above range.

In order to impart slipperiness to the easy-adhesion layer, it is preferred to add particles. It is preferred to use particles having an average particle diameter of 2 μm or less of fine particles. When the average particle diameter of the particles exceeds 2 μm, the particles are liable to fall off from the coating layer. The particles contained in the easy-adhesion layer can be exemplified as the above-mentioned fine particles.

Moreover, as a method of applying a coating liquid, it is possible to use the public A well-known method. For example, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brush method, a spray coating method, an air knife coating method, a wire bar coating method, a tube scraping method, and the like may be mentioned, and these may be carried out singly or in combination.

Further, the measurement of the average particle diameter of the above particles was carried out in accordance with the following method.

A photograph of the particles was taken by a scanning electron microscope (SEM), and the maximum diameter (the distance between the two farthest points) of 300 to 500 particles was measured with a minimum particle size of 2 to 5 mm. The value is taken as the average particle size.

(Method for producing polyester film)

As a method for producing a polyester film, the most common production method is an unaligned polyester obtained by melting a polyester resin and extruding it into a sheet shape, and using a roll speed at a temperature equal to or higher than the glass transition temperature. After the difference is extended in the longitudinal direction, the heat treatment is applied by stretching in the transverse direction by a tenter.

The polyester film may be a uniaxially stretched film or a biaxially stretched film, but when a biaxially stretched film is used as a polarizer protective film, a rainbow color is not observed even when viewed from directly above the film face. Spot, but when viewed from the oblique direction, you will see a rainbow-like stain, and you must pay attention.

This phenomenon is because the biaxially stretched film is composed of a refractive index ellipsoid having a different refractive index in the traveling direction, the width direction, and the thickness direction, and hysteresis becomes zero due to the direction of light penetration inside the film (refractive index ellipse) The direction of seeing it as a true circle exists. If the liquid crystal display is observed from a specific direction in the oblique direction, there is a delay. In the case of a point of zero, the rainbow-like spots appear concentrically around this point. Further, when the angle from the directly upper side (normal direction) of the film surface to the position where the rainbow-colored color spot is seen is θ, the larger the birefringence in the film surface, the larger the angle θ, the rainbow shape The more difficult the color spots are. Since the angle θ of the biaxially stretched film tends to be small, it is preferably a uniaxially stretched film, which is difficult to see due to rainbow-like color spots.

However, in the completely 1-axis (1-axis symmetrical) film, the mechanical strength in the direction orthogonal to the alignment direction is remarkably lowered. It is preferable to have a biaxial property (2-axis symmetry) in a range in which rainbow-like color spots do not substantially occur or a range of rainbow-like color spots does not occur in a viewing angle range required for a liquid crystal display screen.

As an index for judging the visibility of the rainbow-like stain, there is a method of evaluating the difference between the hysteresis (in-plane hysteresis) and the thickness direction retardation (Rth). The thickness direction phase difference means an average of the phase differences obtained by multiplying the two birefringences ΔNxz and ΔNyz by the film thickness d when viewed from the cross section of the film thickness direction. Since the difference between the in-plane hysteresis and the thickness direction hysteresis is smaller, the effect of the birefringence caused by the observation angle is more isotropic, so the change in hysteresis caused by the observation angle is smaller. Therefore, it is difficult to determine the rainbow-like color spots caused by the observation angle.

The ratio of the hysteresis of the polyester film to the retardation in the thickness direction (Re/Rth) is preferably 0.200 or more, more preferably 0.500 or more, and still more preferably 0.600 or more. The greater the ratio of hysteresis to retardation in the thickness direction (Re/Rth), the more the effect of birefringence is increased, and the more the occurrence of rainbow-like stains caused by the observation angle, the more difficult it is to occur. Further, in the completely 1-axis (1-axis symmetrical) film, the ratio of the hysteresis to the retardation in the thickness direction (Re/Rth) becomes 2.0. However, as described above, as the film is nearly completely monoaxial (1-axisymmetric), the mechanical strength in the direction orthogonal to the alignment direction tends to be remarkably lowered.

On the other hand, the ratio of the hysteresis of the polyester film to the retardation in the thickness direction (Re/Rth) is preferably 1.2 or less, more preferably 1.0 or less. In order to completely suppress the occurrence of rainbow-like color spots caused by the observation angle, the ratio of the retardation to the phase difference in the thickness direction (Re/Rth) is not necessarily 2.0, and 1.2 or less is sufficient. Moreover, even if the ratio is 1.0 or less, the viewing angle characteristics required by the liquid crystal display device (180 degrees left and right, 120 degrees above and below) can be sufficiently satisfied.

When the film forming conditions of the polyester film are specifically described, the longitudinal stretching temperature and the lateral stretching temperature are preferably 80 to 130 ° C, particularly preferably 90 to 120 ° C. The longitudinal stretching ratio is preferably 1.0 to 3.5 times, and particularly preferably 1.0 to 3.0 times. Further, the lateral stretching ratio is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times. In order to control the hysteresis within the above range, it is more preferable to control the ratio of the longitudinal stretching ratio to the lateral stretching ratio. If the difference between the vertical and horizontal stretching ratios is too small, it is difficult to produce a hysteresis difference. Further, the setting of the low extension temperature is also preferable in terms of improving the hysteresis. In the subsequent heat treatment, the treatment temperature is preferably from 100 to 250 ° C, particularly preferably from 180 to 245 ° C.

In order to suppress the variation of the hysteresis, the thickness unevenness of the film is preferably small. Since the stretching temperature and the stretching ratio have a large influence on the thickness unevenness of the film, it is necessary to optimize the film forming conditions from the viewpoint of thickness unevenness. In particular, if the longitudinal stretching ratio is lowered in order to generate a hysteresis difference, the longitudinal thickness unevenness is deteriorated. Since the longitudinal thickness unevenness is a region which becomes very bad in a certain range of the stretching ratio, it is preferable to set the film forming conditions outside the range.

The thickness unevenness of the film is preferably 5.0% or less, more preferably 4.5% or less, still more preferably 4.0% or less, and particularly preferably 3.0% or less.

As described above, the hysteresis of the film is controlled to a specific range, and can be carried out by appropriately setting the stretching ratio, the stretching temperature, and the thickness of the film. For example, the higher the stretching ratio, the lower the stretching temperature, and the thicker the film, the easier it is to obtain high hysteresis. Conversely, the lower the stretching ratio, the higher the stretching temperature, and the thinner the thickness of the film, the easier it is to obtain low hysteresis. However, if the thickness of the film is increased, the phase difference in the thickness direction tends to be large. Therefore, the film thickness is preferably set to be appropriately described in the range described later. Further, it is preferable to set the final film forming conditions in consideration of the physical properties required for the processing in addition to the control of the hysteresis.

The thickness of the polyester film is arbitrary, but it is preferably in the range of 15 to 300 μm, more preferably in the range of 15 to 200 μm. Even in the case of a film having a thickness of less than 15 μm, hysteresis of 3000 nm or more can be obtained in principle. However, in this case, the anisotropy of the mechanical properties of the film is remarkable, and cracking, breakage, and the like are likely to occur, and the practicality as an industrial material is remarkably lowered. The lower limit of the particularly preferable thickness is 25 μm. On the other hand, if the upper limit of the thickness of the polarizer protective film exceeds 300 μm, the thickness of the polarizing plate becomes too thick. From the viewpoint of practicality as a protective film for a polarizer, the upper limit of the thickness is preferably 200 μm. The upper limit of the thickness is particularly 100 μm which is equivalent to that of a general TAC film. In the above thickness range, in order to also control the hysteresis within the scope of the present invention, the polyester used as the film substrate is preferably polyethylene terephthalate.

Further, as a method of blending the ultraviolet absorber in the polyester film, a well-known method can be used in combination, for example, by preliminarily A master batch is prepared by blending a dried ultraviolet absorber with a polymer raw material by a kneading extruder, and blending the method of mixing the master batch with a polymer raw material at the time of film formation.

At this time, in order to uniformly disperse the ultraviolet absorber and economically blend, the concentration of the ultraviolet absorber of the master batch is preferably from 5 to 30% by mass. As a condition for producing the master batch, it is preferred to use a kneading extruder and extrude at a temperature of not less than the melting point of the polyester raw material and at a temperature of 290 ° C or lower for 1 to 15 minutes. When it is 290 ° C or more, the amount of reduction of the ultraviolet absorber is large, and the viscosity of the master batch is lowered. When the extrusion temperature is 1 minute or less, the uniform mixing of the ultraviolet absorber becomes difficult. At this time, a stabilizer, a color tone adjuster, and an antistatic agent may be added as needed.

Further, in the present invention, it is preferred that the film has a multilayer structure of at least three or more layers, and an ultraviolet absorber is added to the intermediate layer of the film. A film having a three-layer structure containing an ultraviolet absorber in the intermediate layer can be specifically produced as follows. The granules of the polyester as the outer layer, the masterbatch containing the ultraviolet absorbing agent and the granules of the polyester used as the intermediate layer are mixed in a predetermined ratio, dried, and then supplied to a known extruder for a molten laminate. The slit-shaped die was extruded into a sheet shape, and solidified by cooling on a casting roll to produce an unstretched film. That is, using two or more extruders, a three-layer collecting pipe, or a joining zone (for example, a joining zone having a corner-shaped joining portion), a film layer constituting the two outer layers and a film layer constituting the intermediate layer are laminated. The nozzle was extruded into three sheets and cooled on a casting roll to produce an unstretched film. Further, in order to remove foreign matter contained in the raw material polyester which is a cause of optical defects, it is preferred to perform high-precision filtration at the time of melt extrusion. Filter particles of filter material used in high-precision filtration of molten resin The size (initial filtration efficiency: 95%) is preferably 15 μm or less. When the filtered particle size of the filter medium exceeds 15 μm, the removal of foreign matter of 20 μm or more is likely to be insufficient.

(adhesive)

The polarizer protective film may be laminated on the polarizer via any of the adhesives, or may be laminated directly without the adhesive. The adhesive is not particularly limited, and any one can be used. As an example, a water-based adhesive (that is, a member in which an adhesive component is dissolved in water or dispersed in water) can be used. For example, an adhesive containing a polyvinyl alcohol-based resin and/or a urethane resin as a main component can be used. In order to improve the adhesion, an adhesive which is further blended with an isocyanate compound or an epoxy compound may be used as needed. Moreover, as another example, a photocurable adhesive can also be used. In one embodiment, a solventless ultraviolet curable adhesive is preferred. The photocurable resin may, for example, be a mixture of a photocurable epoxy resin and a photocationic polymerization initiator, and may be used as described in JP-A-2012-203211 or JP-A-2009-227804.

(adhesive layer)

Examples of the adhesive include a rubber-based adhesive, a polyester-based adhesive, an epoxy-based adhesive, an acrylic adhesive, a polyoxygen-based adhesive, a urethane-based adhesive, and a vinyl alkyl ether. The adhesive, the polypropylene amide-based adhesive, the cellulose-based adhesive, and the like are not particularly limited.

Among these, an active energy ray-curable or thermosetting acrylic adhesive, particularly a thermosetting acrylic adhesive, is not affected by the ultraviolet absorber, and the adhesive property can be adjusted, so that it is preferred. .

Acrylate based on base resin of acrylic adhesive ( The copolymer type can be prepared by appropriately adjusting the physical properties such as glass transition temperature (Tg) or molecular weight, by appropriately selecting the type, composition ratio, polymerization condition, and the like of the acrylic monomer or methacrylic monomer used for the polymerization.

Examples of the acrylic monomer constituting the acrylate (co)polymer include 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-butyl acrylate, and ethyl acrylate as main raw materials. .

In addition to these, a (meth)acrylic monomer having a wide variety of functional groups may be copolymerized with the above acrylic monomer for the purpose of cohesive force imparting or polarity imparting.

Examples of the (meth)acrylic monomer having the functional group include methyl methacrylate, methyl acrylate, hydroxyethyl acrylate, acrylic acid, glycidyl acrylate, N-substituted acrylamide, and acrylonitrile. , methacrylonitrile, fluorine-containing alkyl acrylate, acrylate containing an organic decyloxy group, and the like.

Further, various vinyl monomers such as vinyl acetate, alkyl vinyl ether or hydroxyalkyl vinyl ether copolymerizable with the above acrylic monomer or methacrylic acid monomer may also be suitable for polymerization.

As the polymerization treatment using these monomers, a well-known polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, or the like can be employed, which can be carried out by a polymerization method by using a thermal polymerization initiator or photopolymerization. A polymerization initiator such as a reagent to obtain an acrylate copolymer.

The acrylate-based (co)polymer is crosslinked to restrict fluidity and functions as an adhesive. As a method of crosslinking, heat crosslinking or ultraviolet crosslinking, electron beam crosslinking, but not ultraviolet rays are mentioned. In terms of the influence of the line absorber, it is preferably thermal crosslinking or electron beam crosslinking. As a supplementary method of thermal crosslinking, it is preferred to add a crosslinking agent chemically bonded to a reactive group such as a hydroxyl group or a carboxylic acid group introduced in an acrylate (co)polymer, and to react by heating or aging. The method.

Examples of the thermal crosslinking agent include an isocyanate crosslinking agent and an epoxy crosslinking agent, and one type or two or more types can be used.

Examples of the isocyanate crosslinking agent include toluene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, and benzodimethyl diisocyanate. An isocyanate monomer such as diphenylmethane diisocyanate or hydrogenated diphenylmethane diisocyanate, and an isocyanate compound such as an isocyanate compound added to such an isocyanate monomer and trimethylolpropane, or an isocyanurate compound. Diurea type compound, more commonly known polyether polyol or polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol, etc. addition reaction urethane prepolymer Type of isocyanate and the like.

The isocyanate compound exemplified above may be used to protect the isocyanate group by a suitable blocking agent in order to improve workability or storage stability.

Examples of the terminal blocking agent include a phenol type, an anthraquinone type, a caprolactam type, a thiol type, a quinone imine type, a guanamine type, an imidazole type, an alcohol type, an active methylene type, or various amine compounds. The well-known one can be selected according to the dissociation temperature or workability of the blocking agent.

Examples of the epoxy-based crosslinking agent include ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, glycerol diepoxypropyl ether, and glycerol triepoxypropyl ether. 1,3-bis(N,N-diepoxypropylamino) Methyl)cyclohexane, N,N,N',N'-tetraepoxypropyl-m-benzenedimethyldiamine, N,N,N',N'-tetraepoxypropylaminobenzene Methane, trisepoxypropyl iso-cyanate, mN,N-diepoxypropylaminophenylepoxypropyl ether, N,N-diepoxypropyltoluamide, N,N- Di-epoxypropyl aniline and the like.

Further, the content of the crosslinking agent is preferably in the range of 0.5 to 2 equivalents with respect to the amount of the crosslinking functional group introduced into the base polymer.

(backlight source)

The configuration of the backlight may be an edge light method using a light guide plate, a reflection plate or the like as a constituent member, or may be a direct type. In the present invention, as the backlight source of the liquid crystal display device, it is necessary to use a white light-emitting diode (white LED) or a combination of a blue LED and a light source of a quantum dot.

The so-called white LED is a combination of a phosphor, that is, a blue light that uses a compound semiconductor, or a light-emitting diode that emits ultraviolet light and a phosphor, and emits a white component. Among them, a white light-emitting diode formed by combining a blue light-emitting diode using a compound semiconductor and a light-emitting element of a yttrium aluminum garnet-based yellow phosphor is preferably used. Further, a blue LED and a red phosphor, for example, a white LED having a composition of K ₂ SiF ₆ :Mn ⁴⁺ fluoride phosphor (also referred to as "KSF") are combined (Nichia Chemical Industry Co., Ltd.) The NSSW306FT, etc.) is also preferred.

Further, a white LED light source of a phosphor type using a phosphor having a clear emission peak in a region of R (red) and G (green) due to excitation light, and a white light of three wavelengths can be used. A wide variety of light sources, such as LED light sources and white LED light sources combined with red lasers.

Moreover, the application of quantum dot technology to LCDs has attracted attention from the rise in the demand for color gamut expansion in recent years. In an LED that normally uses a white LED as a backlight source, only about 20% of the spectrum that the human eye can recognize can be reproduced. In contrast to this, when a backlight source including a light source that emits excitation light and a light-emitting layer of a quantum dot is used, it is said that a color of about 60% of a spectrum recognizable by a human eye can be reproduced. Practical quantum dots have Nanosys's QDEF ^TM or QD Vision's Color IQ ^TM like.

The light-emitting layer containing the quantum dots is formed by, for example, a quantum dot in a resin material such as polystyrene, and emits a layer of light of each color in units of pixels based on the excitation light emitted from the light source. The light-emitting layer is composed of, for example, a red light-emitting layer disposed on a red pixel, a green light-emitting layer disposed on a green pixel, and a blue light-emitting layer disposed on a blue pixel. In the quantum dots of the light-emitting layer, light rays of different wavelengths (colors) are generated based on the excitation light.

Examples of the material of such a quantum dot include CdSe, CdS, ZnS: Mn, InN, InP, CuCl, CuBr, and Si, and the particle diameter (the size in one direction) of the quantum dots thereof is, for example, 2 to 20 nm. about. Further, among the above-mentioned quantum dot materials, InP, as the red light-emitting material, CdSc is exemplified as the green light-emitting material, and CdS is exemplified as the blue light-emitting material. In such a light-emitting layer, it was confirmed that the light-emitting wavelength changes by changing the size (particle diameter) of the quantum dot or the composition of the material. The size (particle size) or material of the quantum dot is controlled, mixed in the resin material, and used for color separation coating per pixel.

As a light source that emits excitation light, a blue LED is used, but Laser light such as a semiconductor laser is also used. The excitation light from the light source generates an emission spectrum having a peak top in each wavelength region of 400 nm or more and less than 495 nm, 495 nm or more to less than 600 nm, and 600 nm or more and 750 nm or less by passing through the light-emitting layer. At this time, the narrower the half value of the peak of each wavelength region is, the wider the color gamut is. However, if the half value of the peak is narrowed, the luminous efficiency is lowered. Therefore, the luminescence spectrum is designed according to the balance between the required color gamut and the luminous efficiency. shape.

[Examples]

In the following, the present invention will be more specifically described by the following examples, but the present invention is not limited by the following examples, and may be appropriately modified and implemented within the scope of the invention. Within the technical scope of the invention. In addition, the evaluation method of the physical property in the following examples is as follows.

(1) Hysteresis (Re)

The so-called hysteresis is a parameter defined by the product of the anisotropy (ΔNxy=|Nx-Ny|) of the orthogonal biaxial refractive index on the film and the film thickness d (nm) (ΔNxy×d). It is a measure of the isotropy and anisotropy of optics. The anisotropy (ΔNxy) of the biaxial refractive index is obtained by the following method. Using two polarizing plates, the direction of the alignment axis of the film was determined, and the direction of the alignment axis was orthogonal, and a rectangle of 4 cm × 2 cm was cut out and used as a sample for measurement. For this sample, an orthogonal biaxial refractive index (Nx, Ny) and a refractive index (Nz) in the thickness direction were obtained by an Abbe refractometer (NAR-4T, manufactured by ATAGO Co., Ltd., measuring wavelength: 589 nm). The absolute value (|Nx-Ny|) of the above-described biaxial refractive index difference is taken as the anisotropy (ΔNxy) of the refractive index. The thickness d (nm) of the film is electricity The gas micrometer (manufactured by FEINPRUF, Millitron 1245D) was measured and converted into nm. The hysteresis (Re) is obtained by the product of the anisotropy of the refractive index (ΔNxy) and the thickness d (nm) of the film (ΔNxy × d).

(2) Thickness direction hysteresis (Rth)

This is a parameter indicating the average of the hysteresis obtained by multiplying the two birefringences ΔNxz (|Nx-Nz|) and ΔNyz (|Ny-Nz|) by the film thickness d from the cross section in the thickness direction of the film. In the same manner as the measurement of the hysteresis, Nx, Ny, Nz and the film thickness d (nm) were obtained, and the average values of (ΔNxz × d) and (ΔNyz × d) were calculated to obtain the thickness direction retardation (Rth). .

(3) Light transmittance at a wavelength of 380 nm

Using a spectrophotometer (manufactured by Hitachi, Ltd., model U-3500), the light transmittance at a wavelength of 300 to 500 nm was measured using an air layer as a standard, and the light transmittance at a wavelength of 380 nm was obtained.

(Manufacturing Example 1 - Polyester A)

The temperature of the esterification reaction tank was raised, and 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged at a time point of reaching 200 ° C, and 0.017 parts by mass of antimony trioxide as a catalyst was charged while stirring. 0.064 parts by mass of magnesium acetate tetrahydrate and 0.16 parts by mass of triethylamine. Subsequently, the temperature was raised under pressure, and the pressure esterification reaction was carried out under the conditions of a gauge pressure of 0.34 MPa and 240 ° C. Thereafter, the esterification reaction tank was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260 ° C for 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Then, after 15 minutes, the dispersion treatment was carried out in a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tank, and a polycondensation reaction was carried out at 280 ° C under reduced pressure.

After the end of the polycondensation reaction, the diameter of 5 μm was filtered out by 95%. The NASLON filter was subjected to filtration treatment, and a strand shape was extruded from a nozzle, and cooled, solidified, and cut into pellets using cooling water which had been previously subjected to filtration treatment (pore diameter: 1 μm or less). The intrinsic viscosity of the obtained polyethylene terephthalate resin (A) was 0.62 dl/g, and the inactive particles and the internal precipitated particles were substantially not contained. (hereinafter, referred to as PET (A)).

(Manufacturing Example 2 - Polyester B)

Mix 10 parts by mass of dried UV absorber (2,2'-(1,4-phenylene) bis(4H-3,1-benzo) -4-ketone), 90 parts by mass of PET (A) containing no particles (inherent viscosity: 0.62 dl/g), and a polyethylene terephthalate resin containing an ultraviolet absorber was obtained by using a kneading extruder ( B). (hereinafter, referred to as PET (B)).

(Manufacturing Example 3 - Adjustment of Adhesive Modified Coating Liquid)

The transesterification reaction and the polycondensation reaction were carried out by a usual method to prepare 46 mol% of terephthalic acid, 46 mol% of isophthalic acid and 8 mol% as a dicarboxylic acid component (for the entire dicarboxylic acid component). Sodium 5-sulfoisophthalate, water-dispersible sulfonate metal salt group composed of 50 mol% ethylene glycol and 50 mol% neopentyl glycol as a diol component (for the entire diol component) Copolymerized polyester resin. Next, 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, followed by heating and stirring, and when it reached 77 ° C, 5 was added. The mass fraction of the above-mentioned copolymerized polyester resin containing a water-dispersible sulfonic acid metal salt group is further stirred until the resin block disappears, and then the aqueous resin dispersion liquid is cooled to room temperature to obtain a uniform water having a solid content concentration of 5.0% by mass. Dispersive copolymerization of polyester resin liquid. In addition, 3 parts by mass of aggregated vermiculite particles (Sylysia, manufactured by Fuji SILYSIA Co., Ltd.) After dispersing in 50 parts by mass of water, 0.54 parts by mass of the aqueous dispersion of Sylysia 310 is added to 99.46 parts by mass of the water-dispersible copolymerized polyester resin liquid, and 20 parts by mass of water is added while stirring. An adhesive modified coating liquid was obtained.

(Example 1)

(Single-axis alignment PET film 1)

As a raw material for the base film intermediate layer, 90 parts by mass of the PET (A) resin particles containing no particles and 10 parts by mass of the PET (B) resin particles containing the ultraviolet absorber were dried at 135 ° C under reduced pressure (1 Torr) 6 After an hour, it is supplied to the extruder 2 (for the intermediate layer II layer), and the PET (A) is dried by a usual method and supplied to the extruder 1 (for the outer layer I and the outer layer III), and dissolved at 285 ° C. . Each of the two types of polymers was filtered with a filter material of a stainless steel sintered body (95% filtration of a nominal filtration precision of 10 μm particles), and laminated in two types of three-layered mixing zones, and extruded into a sheet shape from a nozzle, and then applied by static electricity. The casting method was wound on a casting drum having a back surface temperature of 30 ° C to be cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the ratio of the thickness of the I layer, the II layer, and the III layer was 10:80:10.

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

The unstretched film on which the coating layer was formed was guided to a tenter stretching machine, and while grasping the end portion of the film with a jig, it was guided to a hot air region at a temperature of 125 ° C and extended 4.0 times in the width direction.

Subsequently, the extended width in the width direction is maintained, treated at a temperature of 225 ° C for 30 seconds, and then subjected to a relaxation treatment of 3% in the width direction. Uniaxially oriented PET film 1 having a film thickness of about 50 μm. The in-plane retardation Re was 5177 nm, the Re/Rth was 0.784, and the light transmittance at a wavelength of 380 nm was 8.5%.

(Single-axis alignment PET film 2)

In addition, as the raw material for the base film intermediate layer, the PET (A) resin particles containing no particles are used, and the PET (B) resin particles containing the ultraviolet absorber are used in the same manner as the above-described uniaxially-oriented PET film 1 In the method, a uniaxially oriented PET film 2 was obtained. The in-plane retardation Re was 5177 nm, the Re/Rth was 0.784, and the light transmittance at a wavelength of 380 nm was 79.0%.

(visual identification side polarizer)

On one side of the polarizer formed of PVA and iodine, the uniaxially oriented PET film 1 is attached to the opposite side of the film by the adhesion of the polarizer and the alignment axis of the film. A TAC film (manufactured by Fujifilm Co., Ltd., thickness: 80 μm, and a UV absorber in the retardation film) was attached via an adhesive. On the opposite side of the contact surface of the TAC film with the polarizer, an adhesive layer is provided to form a visually-identifying side polarizing plate. Further, the light-receiving side polarizing plate has a light transmittance of 5% or less at a wavelength of 380 nm.

(light source side polarizer)

On one side of the polarizer formed of PVA and iodine, the uniaxially oriented PET film 2 is attached to the opposite side of the film by the adhesive agent having the absorption axis of the polarizer perpendicular to the alignment axis of the film. A TAC film (manufactured by Fujifilm Co., Ltd., thickness: 80 μm, and a UV absorber in the retardation film) was attached via an adhesive. An adhesive layer is provided on the opposite side of the TAC film from the contact surface of the polarizer to form a light source side polarizing plate. Light The ultraviolet absorber is not used in any of the members of the source side polarizing plate. Further, the light source side polarizing plate has a light transmittance of more than 10% at a wavelength of 380 nm.

(liquid crystal display device)

The light source side polarizing plate is attached to the liquid crystal cell in such a manner that the adhesive layer of the light source side polarizing plate is in contact with the liquid crystal cell, and the adhesive layer of the side polarizing plate is visually recognized to be in contact with the liquid crystal cell to visually The side polarizing plate is attached to the liquid crystal cell, and a white LED light source (Nissan Chemical, NSPW500CS) made of a light-emitting element combining a blue light-emitting diode and a yttrium aluminum garnet-based yellow phosphor is used as a backlight. A light source is used to manufacture a liquid crystal display device. The liquid crystal display device can be manufactured at low cost and is excellent in visibility.

[Industrial availability]

According to the present invention, a liquid crystal display device having excellent visibility can be provided at low cost, and the industrial use possibility is extremely high.

Claims (2)

A liquid crystal display device comprising a backlight source, a light source side polarizing plate, a liquid crystal cell, and a liquid crystal display device with a viewing side polarizing plate, wherein the light source side polarizing plate and the visual recognition side polarizing plate are each in a polarizing plate. A polarizer protective film is laminated on at least one side thereof, and has an adhesive layer for bonding to a liquid crystal cell. The visible side polarizing plate contains an ultraviolet absorber, and the light source side polarizing plate does not contain an ultraviolet absorber. The liquid crystal display device of claim 1, wherein the polarizer protective film on the visual recognition side of the visual recognition side polarizing plate is a polyester film having a retardation of 3,000 to 30,000 nm, and the polyester film contains an ultraviolet absorber.