JP5151296B2 - Liquid crystal display device provided with adhesive layer and set of composite polarizing plate used therefor - Google Patents

Description

  The present invention relates to a liquid crystal display device that is less likely to cause a color shift depending on the viewing angle during black display and has a wide viewing angle characteristic. The present invention also relates to a set of composite polarizing plates useful for it, disposed on both sides of the liquid crystal cell.

  In recent years, light-weight and thin liquid crystal display devices (LCDs) that consume less power, are driven at a low voltage, and have become rapidly popular as information display devices such as mobile phones, personal digital assistants, computer monitors, and televisions. ing. In this situation, market demands for improving the display quality, size, thickness and weight of liquid crystal display devices are increasing. In particular, there is a remarkable increase in the size of liquid crystal display devices for televisions, and since it is assumed that the image is viewed from various angles on a large screen, further improvements in viewing angle characteristics and screen uniformity are required.

  Currently, a vertical alignment (VA) mode liquid crystal display device is used as a mainstay of a liquid crystal television. The VA mode liquid crystal display device can obtain almost perfect black display when viewed from the front, and can realize a high contrast ratio. However, in such a VA mode liquid crystal display device having only a polarizing plate in a liquid crystal cell, the axial angle of the disposed polarizing plate is shifted from 90 ° when viewed obliquely, and the cell Due to the fact that the rod-like liquid crystal molecules in the inner layer exhibit birefringence, light leakage occurs and the contrast ratio is significantly reduced.

  In order to eliminate such light leakage, it is necessary to dispose an optical compensation film between the liquid crystal cell and the linear polarizing plate. Conventionally, a biaxial retardation plate is provided between the liquid crystal cell and the upper and lower polarizing plates, respectively. Specifications such as placing one sheet at a time, uniaxial retardation plate and full biaxial retardation plate one by one above and below the liquid crystal cell, or both on one side of the liquid crystal cell are adopted. It has been. For example, Japanese Patent Laid-Open No. 2001-109009 (Patent Document 1) discloses that in a vertical alignment mode liquid crystal display device, an a-plate (that is, a positive uniaxial retardation) is provided between an upper and lower polarizing plates and a liquid crystal cell. Plate) and c-plate (ie, a fully biaxial retardation plate) are described.

  On the other hand, a backlight in a liquid crystal display device is usually composed of a cold cathode fluorescent lamp (CCFL), from which three primary colors of red (R), green (G) and blue (B) are displayed. White light is emitted, and is divided into red, green, and blue by a color filter, and each color is displayed. When the screen of the liquid crystal display device is viewed obliquely, the wavelength dispersion characteristics of the retardation value in the liquid crystal layer and the optical film differ depending on the viewing angle, so that the balance of the transmitted red, green, and blue light is lost. A color shift different from the original color may occur. In particular, the coloring phenomenon in the black display state is a serious problem in terms of display quality of the liquid crystal display device. Even if a retardation plate (optical compensation film) as shown in Patent Document 1 is arranged, color shift compensation is not sufficient when the black display state is viewed obliquely.

  In order to compensate for such a color shift, JP-T-2006-515686 (Patent Document 2) states that the wavelength dispersion characteristic of the in-plane retardation value decreases as the wavelength becomes shorter. A biaxial retardation compensation film, which is “dispersion” and the wavelength dispersion characteristic of the retardation value in the thickness direction of the film is “forward wavelength dispersion” in which the retardation value increases as the wavelength becomes shorter, between the liquid crystal cell and the upper and lower polarizing plates. It has been proposed to arrange at least one of the above. Forming a copolymer of a first monomer having positive intrinsic birefringence and a second monomer having negative intrinsic birefringence as a method for producing a biaxial retardation compensation film exhibiting such characteristics In addition, a configuration is shown in which at least two retardation films having different wavelength dispersion characteristics of in-plane retardation values and thickness direction retardation values are laminated. However, in the case of a copolymer, the combination of monomers is limited, and when two or more retardation films are laminated, the process becomes complicated, which is disadvantageous in terms of productivity, There is a problem that the thickness is remarkably increased.

  Further, the polarizing plate is usually used in a form in which a transparent protective layer is provided on one or both sides of the polarizer, and triacetyl cellulose is generally used as the transparent protective layer. Many attempts have been made to replace it with a resin or to give a phase difference to the protective layer. For example, JP-A-7-287123 (Patent Document 3) describes that a protective layer of a polarizer is composed of a cyclic olefin resin, and JP-A-8-43812 (Patent Document 4) It describes that at least one of the protective layers of the polarizer is composed of a resin film having the function of a retardation film.

  Furthermore, JP-A-2006-63195 (Patent Document 5) discloses a dye having an absorption maximum in a wavelength region of 420 nm to 530 nm and / or 530 nm in a pressure-sensitive adhesive containing fine particles and imparting light diffusibility. It is described that color reproducibility can be improved by applying a pressure-sensitive adhesive sheet containing a pigment having an absorption maximum in a wavelength region of ˜630 nm to a liquid crystal display device or the like.

JP 2001-109909 A (Claim 15 and paragraph 0036) JP-T-2006-515686 (= WO2004 / 068226; claims 1, 2, 6, 8, 9 and 10) JP 7-287123 A JP-A-8-43812 JP 2006-63195 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device having a wide viewing angle characteristic that does not easily cause a color shift depending on the viewing angle at the time of black display by using simple means without adding new members. It is in. Another object of the present invention is to provide a set of composite polarizing plates useful for this liquid crystal display device, in which polarizing plates and retardation plates are respectively laminated and disposed on both sides of a liquid crystal cell. .

  The inventor has conducted intensive research to solve the problem of color shift in liquid crystal display devices. As a result, it has been found that the color shift caused by the change in the viewing angle is caused by the change in the balance between the red light and the blue light among the components of the light emitted from the backlight. That is, in the coloring phenomenon that occurs when the liquid crystal display screen is viewed from an oblique direction, the hue is largely due to the characteristics of the retardation plate disposed in the liquid crystal display device, and in particular, it has a large effect on the in-plane retardation value. receive. Specifically, in the liquid crystal display device in which retardation plates having biaxial orientation and in-plane retardation Ro in the range of 30 nm to 100 nm are provided on both sides of the liquid crystal cell, the two retardation plates are provided. In the case of having an in-plane retardation of 30 nm or more and 60 nm or less, in the black display state, transmission of red light is increased as compared with blue light, while the retardation plate has an in-plane retardation of more than 60 nm and 100 nm or less. If so, the transmission of blue light is increased over red light. That is, it has been found that the color shift in black display can be improved by correcting the balance between red light and blue light in the oblique transmitted light.

  By adding a dye having an absorption peak at a specific wavelength to the pressure-sensitive adhesive that joins the phase difference plate and the liquid crystal cell, the liquid crystal display device can be manufactured by simple means without increasing the number of new members. It was found that the color shift when viewed from an oblique direction can be improved. When such a method is used, the optical path length through which the light emitted from the light source passes through the dye-containing layer becomes longer as the polar angle (tilt angle from the normal direction) increases, so the hue at the front where the polar angle is zero Can improve coloring when viewed from an angle with minimal influence. That is, it has been clarified that by selecting the absorption wavelength region of the dye, an effect is exhibited in reducing color loss from an oblique direction.

Therefore, according to the present invention, a liquid crystal display device having the following configuration is provided.
A retardation plate and a polarizing plate are laminated in this order on both sides of the liquid crystal cell via an adhesive layer, respectively, and a backlight is disposed on one side thereof;
Each two of the phase difference plate disposed on both sides of the liquid crystal cell, the slow axis direction of the in-plane refractive index n _x, the refractive index in a direction perpendicular to the slow axis in the plane n _y, the thickness direction refractive index of as n _z, satisfies the relation of _{n x> n y> n z} , and the in-plane retardation Ro is in the range of 30nm or more 100nm or less;
At least one of the pressure-sensitive adhesive layers disposed on both sides of the liquid crystal cell contains a dye; and
When the two retardation plates each have an in-plane retardation Ro of 30 nm or more and 60 nm or less, the dye exhibits a maximum absorption wavelength at 560 to 630 nm,
When the two retardation plates each have an in-plane retardation Ro of more than 60 nm and not more than 100 nm, the dye exhibits a maximum absorption wavelength at 430 to 510 nm.

  As a polarizing plate constituting this liquid crystal display device, a polarizer having a transparent protective layer formed on one side of a polarizer made of polyvinyl alcohol resin is employed, and the retardation plate is bonded to the opposite side of the transparent protective layer. This structure is advantageous from the viewpoint of reducing the overall thickness.

In addition, according to the present invention, a set of composite polarizing plates useful for the liquid crystal display device as described above is also provided, and this set of composite polarizing plates is disposed on both sides of the liquid crystal cell and is positioned on each polarizing plate. A phase difference plate and a pressure-sensitive adhesive layer are laminated in this order;
The retardation plate constituting the respective composite polarizing plate, a slow axis direction of the refractive index n _x in the plane, the refractive index in a direction perpendicular to the slow axis in the plane n _y, the refractive index in the thickness direction as n _z, it satisfies the relation of _{n x> n y> n z} , and the in-plane retardation Ro is in 100nm following range of 30 nm;
At least one of the pressure-sensitive adhesive layers constituting each composite polarizing plate contains a dye; and
When the retardation plate constituting each composite polarizing plate has an in-plane retardation R o of 30 nm or more and 60 nm or less, the dye exhibits a maximum absorption wavelength at 560 to 630 nm,
When the phase difference plate constituting each composite polarizing plate has an in-plane retardation Ro of more than 60 nm and not more than 100 nm, the dye exhibits a maximum absorption wavelength at 430 to 510 nm.

  Also in this set of composite polarizing plates, the polarizing plate constituting each composite polarizing plate is constituted by a transparent protective layer formed on one side of a polarizer made of a polyvinyl alcohol resin, and is opposite to the transparent protective layer. The structure in which the retardation plate is bonded to the side is advantageous from the viewpoint of reducing the overall thickness.

  In the liquid crystal display device of the present invention, the color shift depending on the viewing angle in the black display state is improved by simple means without adding new members, and the viewing angle characteristics are good. The set of composite polarizing plates of the present invention is advantageously used for this liquid crystal display device. In these liquid crystal display devices or composite polarizing plate sets, the polarizing plate is constituted by a transparent protective layer formed on one side of a polarizer made of a polyvinyl alcohol resin, and a retardation plate on the opposite side of the transparent protective layer If it is set as the structure by which was bonded, it will contribute also to thickness reduction of a liquid crystal display device.

  Hereinafter, the present invention will be described in detail. An example of a basic layer structure of the liquid crystal display device according to the present invention is shown in a schematic cross-sectional view in FIG. In the liquid crystal display device of the present invention, the retardation plate 30 and the polarizing plate 20 are laminated in this order on one side of the liquid crystal cell 60 via the adhesive layer 40, and the adhesive is also provided on the other side of the liquid crystal cell 60. A retardation film 35 and a polarizing plate 25 are laminated in this order via a layer 45, and the backlight 10 is disposed on one side thereof. Such a layer structure itself is not different from a known liquid crystal display device.

  Further, in the present specification, what is obtained by laminating a retardation plate on a polarizing plate, or in which an adhesive layer for bonding to a liquid crystal cell is formed on the retardation plate side is referred to as a “composite polarizing plate”. I will call it. The polarizing plate 20 has a retardation plate 30 and an adhesive layer 40 laminated in this order, and the polarizing plate 25 has a retardation plate 35 and an adhesive layer 45 laminated in this order. 55, a set of composite polarizing plates disposed on both sides of the liquid crystal cell 60 is configured.

In the set of the liquid crystal display device or the composite polarizing plate, the light incident side retardation plate 30 disposed between the light incident side polarizing plate 20 and the liquid crystal cell 60 and the light emitting side polarizing plate 25 and the liquid crystal cell 60 are disposed. as the light emitting side phase plate 35 to be disposed, three axial directions of the refractive indices n _x, n _y and n _z is, n _x> n _y> satisfy the relation of n _z, in-plane retardation Ro is 30nm or more 100nm A light incident side pressure-sensitive adhesive layer 40 that joins the light incident side phase difference plate 30 and the liquid crystal cell 60, and the light output side phase difference plate 35 and the liquid crystal cell 60 that are used in the following ranges are used. At least one of the light emitting side pressure-sensitive adhesive layers 45 to be contained contains a pigment.

  A polarizing plate is generally used in a form in which a transparent protective layer is formed on at least one surface of a polarizer made of a polyvinyl alcohol-based resin. The polarizer has a property of transmitting linearly polarized light having a vibration vector in a certain direction and absorbing linearly polarized light having a vibration vector in a direction orthogonal to the light incident perpendicularly to the film surface. Such a polarizer can be produced by a known method. Specifically, it can be obtained by subjecting a polyvinyl alcohol resin film to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment. The thickness of the polarizer is about 5 to 40 μm. As the transparent protective layer, various transparent resin films can be used. Examples of the resin include cellulose acetate resins represented by diacetyl cellulose and triacetyl cellulose, and cyclic olefin resins represented by norbornene resins. Examples thereof include a resin, an acrylic resin, and a polyolefin resin.

  The polarizing plates 20 and 25 in the present invention can also be configured by a transparent protective layer formed on at least one surface of a polarizer made of the polyvinyl alcohol resin as described above. It is advantageous to form the polarizing plates 20 and 25 with the transparent protective layers 22 and 27 formed on one side, respectively, and arrange the retardation plates 30 and 35 on the opposite side of the transparent protective layers 22 and 27. By adopting such a configuration, it is possible to reduce the thickness and weight of the composite polarizing plate, which is a laminate of the polarizing plate and the retardation plate, and further reduce the number of components of the liquid crystal display device, thereby reducing the production process. This simplifies and improves the yield.

  In general, the transparent protective layers 22 and 27 are composed of a transparent resin film having an in-plane retardation of almost zero. In particular, it is preferably composed of a cellulose acetate-based resin film, particularly triacetylcellulose. Examples of commercially available triacetyl cellulose films include “Fujitack Film” (available in various grades) sold by Fuji Film Co., Ltd. and “KC8UX2M” and “Konica Minolta Opto Co., Ltd.” KC8UY ”etc. (both are trade names). The transparent protective layer made of a cellulose acetate-based resin is usually subjected to saponification treatment in order to improve adhesion with the polarizer. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

  When the transparent protective layer 27 located on the viewing side of the light emitting side polarizing plate 25 is composed of a cellulose acetate-based resin film, the antiglare treatment, the hard coat treatment, the antistatic treatment, and the reflection are applied to the surface according to the application. Surface treatment such as prevention treatment may be performed.

Next, the phase difference plates 30 and 35 will be described. Plane retardation Ro and the thickness direction retardation Rth of the film exhibiting optical anisotropy, the refractive index of the three axial directions as defined above n _x, n _y and n _z, the thickness is taken as d, the following (1) and (2).

_{Ro = (n x -n y)} × d (1)
Rth = _{[(n x + n y) /} 2-n z ] × d (2)

In the present invention, as the phase difference plate 30 and 35 arranged on both sides of the liquid crystal cell, n _x> n _y> satisfy the relation of n _z, the equation (1) in-plane retardation Ro defined by at least 30nm The thing of 100 nm or less is adopted. Relationship former n _x> n _y> n _z are the three-axial refractive indices n _x, of n _y and n _z, the largest refractive indices n _x of the in-plane slow axis direction, the thickness direction refractive It means that the ratio _nz is the smallest, that is, biaxial orientation.

  When the in-plane phase difference Ro of the light incident side phase difference plate 30 and the light emission side phase difference plate 35 is 30 nm or less, the viewing angle compensation of the polarization axis is insufficient, and light leakage from the oblique angle in black display is caused. The color change increases. On the other hand, if Ro exceeds 100 nm, the viewing angle is over-compensated, which adversely affects light loss and color change. Further, each thickness direction retardation Rth is relatively large, and is preferably set to a value larger than the in-plane retardation Ro. Specifically, from the range of about 70 to 300 nm, the characteristics of the liquid crystal cell. It is preferable to select according to. Similarly to Ro, if Rth is too small, the viewing angle compensation of the liquid crystal layer becomes insufficient. Conversely, if Rth is too large, overcompensation occurs. Thus, as the light incident side phase difference plate 30 and the light emission side phase difference plate 35, a film having a biaxial orientation and an in-plane phase difference Ro of 30 nm or more and 100 nm or less is adopted. Compensation can be performed, and light omission and color change when the black display state is viewed from an oblique direction can be suppressed.

  Moreover, it is preferable to comprise the light-incidence side phase difference plate 30 and the light emission side phase difference plate 35 with the cyclic olefin resin film or the cellulose acetate type resin film which satisfy | fills the said conditions. These may be composed of the same type of resin film or different types of resin films.

  The cyclic olefin-based resin used for the phase difference plates 30 and 35 is a thermoplastic resin having a monomer unit made of a cyclic olefin such as norbornene or a polycyclic norbornene-based monomer. It can be a hydrogenated product of a ring-opening copolymer using a combination or two or more kinds of cyclic olefins, and can also be an addition copolymer of a cyclic olefin and a chain olefin or an aromatic compound having a vinyl group. Also good. In addition, a polar group may be introduced.

  In the case of a copolymer of a cyclic olefin and a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene, and examples of the aromatic compound having a vinyl group Examples thereof include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the unit of the monomer comprising the cyclic olefin may be 50 mol% or less, for example, about 15 to 50 mol%. In particular, when a terpolymer of a cyclic olefin, a chain olefin, and an aromatic compound having a vinyl group is used, the monomer unit composed of the cyclic olefin can have a relatively small amount. In such a terpolymer, the unit of monomer composed of a chain olefin is usually about 5 to 80 mol%, and the unit of monomer composed of an aromatic compound having a vinyl group is usually about 5 to 80 mol%.

  Commercially available thermoplastic cyclic olefin resins such as “Topas” sold by Ticona, Germany, “ARTON” sold by JSR Co., Ltd., and sold by Nippon Zeon Co., Ltd. There are “ZEONOR” and “ZEONEX”, “Apel” sold by Mitsui Chemicals, Inc. (all are trade names). Such a cyclic olefin-based resin is formed into a film, and a known film forming method such as a solvent casting method or a melt extrusion method is appropriately used for forming the film. The formed cyclic olefin resin film is also commercially available, for example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Arton Film” sold by JSR Corporation, There are “Zeonor Film” and the like (all are trade names) sold by Optes.

  The cyclic olefin-based resin film can be given an arbitrary retardation value by stretching. In general, stretching is performed continuously while unwinding the film from the roll, and the film is stretched in a heating furnace in the traveling direction of the roll film or in a direction perpendicular to the traveling direction. As the temperature of the heating furnace, a range from the vicinity of the glass transition temperature of the cyclic olefin resin to the glass transition temperature + 100 ° C. is usually employed. The draw ratio is usually about 1.1 to 6 times, preferably 1.1 to 3.5 times. In order to satisfy the refractive index characteristics defined in the present invention, biaxial stretching is employed. When the retardation plate is composed of a cyclic olefin-based resin film, it is preferable to perform surface activation treatment such as corona treatment on the adhesion surface with the polarizer in order to enhance adhesion with the polarizer.

  Similarly, the cellulose acetate-based resin used as the phase difference plate is one in which at least a part of cellulose is converted to acetate ester, and examples thereof include triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate. The cellulose acetate-based resin film can also be given an arbitrary retardation value by stretching. The cellulose acetate-based resin film in which retardation is expressed has characteristics such as low birefringence and wavelength dispersion characteristics such as “reverse wavelength dispersion” in which the retardation value decreases as the wavelength becomes shorter. Cellulose acetate-based resin films with biaxial orientation retardation developed by stretching are also commercially available. For example, “KC4FR-T” and “KC8UCR-5” sold by Konica Minolta Opto Co., Ltd. Etc. (both are trade names). When the retardation plate is composed of a cellulose acetate-based resin film, the same saponification treatment as that described for the transparent protective layer is usually performed in order to enhance the adhesion to the polarizer.

  The phase difference plate 30 arranged on the light incident side of the liquid crystal cell and the phase difference plate 35 arranged on the light emission side can be made of the same kind of resin film, but both are made of different resin films. You can also. For example, one of the two retardation plates 30 and 35 may be a cellulose acetate resin film and the other may be a cyclic olefin resin film. If the light incident side phase difference plate 30 is composed of a cyclic olefin resin film with little dimensional change due to heat and the light output side phase difference plate 35 is composed of a cellulose acetate resin film, the light incident side due to heat of the backlight 10 Since the deformation of the phase difference plate 30 can be suppressed and the bending direction of the panel can be controlled in a preferable direction, it is effective in suppressing the frame unevenness and the display quality can be improved. Moreover, if the light emission side phase difference plate 35 is made of a cyclic olefin resin film having a low hygroscopic property and the light incidence side phase difference plate 30 is made of a cellulose acetate resin, the environment is changed from a high humidity environment to a low humidity environment. When moved, the light exit side retardation plate 35 is less contracted by moisture release and the bending of the panel is suppressed, so that light leakage is less likely to occur.

  The thickness of the phase difference plates 30 and 35 is preferably thin. However, if the thickness is too thin, the strength is lowered and the workability is inferior. On the other hand, if the thickness is too thick, the transparency is lowered or a laminate with a polarizing plate. Problems such as an increase in the weight of the composite polarizing plate arise. Accordingly, an appropriate thickness of the retardation films 30 and 35 is, for example, about 5 to 200 μm, and preferably 20 to 100 μm. In particular, when a cellulose acetate-based resin film is employed, it is more preferable to set the thickness to 20 to 100 μm, especially 20 to 60 μm in consideration of the influence on the phase difference caused by the stress generated by the heat of the backlight. Ideally, it is 35 to 45 μm.

  The polarizer 21, the transparent protective layer 22 and the phase difference plate 30 in the light incident side composite polarizing plate 50, and the polarizer 26, the transparent protective layer 27 and the phase difference plate 35 in the light output side composite polarizing plate are respectively bonded via an adhesive. Are preferably laminated. The adhesive used for this purpose can use an appropriate thing in consideration of each adhesiveness. An aqueous solution of a polyvinyl alcohol-based resin is one of preferred adhesives, and this aqueous solution preferably further contains a curing agent such as a water-soluble epoxy resin or a polyvalent aldehyde.

  After laminating the transparent protective layer and the retardation film on the polarizer, a drying process is performed. A drying process is performed by spraying a hot air, for example, and the temperature at that time is suitably selected from the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. The drying time is about 20 to 1,200 seconds. When a cyclic olefin-based resin film is used as the retardation plate, it is preferably cured after drying for 12 to 600 hours at room temperature or slightly higher, for example, at a temperature of about 20 to 50 ° C. The temperature at the time of curing is generally set lower than the temperature adopted at the time of drying.

  The polarizers 21 and 26 in the light incident side polarizing plate 20 and the light emitting side polarizing plate 25 each have an absorption axis in the plane. The retardation plates 30 and 35 laminated thereon exhibit refractive index anisotropy as is apparent from the above definition, and therefore there are a slow axis and a fast axis in the plane. The slow axis and the fast axis are orthogonal to each other in the plane. The polarizer 21 constituting the light incident side polarizing plate 20 and the phase difference plate 30 disposed on the liquid crystal cell side, and the polarizer 26 constituting the light emitting side polarizing plate 25 and the position disposed on the liquid crystal cell side. The phase difference plate 35 may be disposed so that the absorption axis of the polarizer and the in-plane slow axis of the phase difference plate are in a substantially parallel relationship or a substantially orthogonal relationship. In particular, it is preferable in terms of productivity to arrange the two so as to be substantially orthogonal. That is, the film exhibiting biaxial orientation to the extent defined as the retardation plates 30 and 35 in the present invention is preferably produced by a stretching operation mainly composed of transverse stretching, in which case the slow axis represents the roll film width. Since the roll film is bonded to the polarizer whose roll axis is the longitudinal direction (flow direction) of the roll film, the absorption axis of the polarizer and the slow axis of the retardation plate are orthogonal to each other. Become a relationship. Further, the light incident side polarizing plate 20 and the light emitting side polarizing plate 30 are usually arranged so that their absorption axes are orthogonal to each other, and are used in a normally black mode.

  As for the composite polarizing plates 50 and 55, an adhesive layer is formed in the single side | surface or both surfaces. In the present invention, the pressure-sensitive adhesive layers 40 and 45 are formed on the side bonded to the liquid crystal cell 60, that is, on the outer sides of the phase difference plates 30 and 35, respectively. The pressure-sensitive adhesive layers 40 and 45 include, for example, an acrylic resin, a styrene resin, a silicone resin, or the like as a base polymer, and further include a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound. It can be formed from a pressure-sensitive adhesive composition containing a ring agent or the like. The thickness of the pressure-sensitive adhesive layers 40 and 45 is usually about 5 to 100 μm, preferably 5 to 40 μm. If the pressure-sensitive adhesive layer is too thin, the tackiness is lowered, and if it is too thick, problems such as the pressure-sensitive adhesive protruding easily occur.

  In the present invention, at least one of the pressure-sensitive adhesive layers 40 and 45 contains a dye that exhibits maximum absorption at a specific wavelength.

  As a dye to be contained in at least one of the pressure-sensitive adhesive layers 40 and 45, when the retardation plates 30 and 35 disposed on both sides of the liquid crystal cell 60 each have an in-plane retardation Ro of 30 to 60 nm, When the one having a maximum absorption wavelength at 560 to 630 nm is employed, and each of the retardation plates 30 and 35 has an in-plane retardation Ro of 60 nm or more and 100 nm or less, the maximum absorption wavelength is shown at 430 to 510 nm. Adopt things. In this way, by blending dyes having different wavelengths that exhibit the maximum absorption due to the in-plane retardation of the retardation plates 30 and 35, the color shift when the liquid crystal display device is viewed obliquely is effectively reduced. be able to. When the retardation plates 30 and 35 each have an in-plane retardation Ro of around 60 nm, the color shift is not so great, and the display is not greatly impaired even if no dye is added to the adhesive. However, even in this case, it is effective from the viewpoint of further reducing the color shift to add any one of the above dyes according to the retardation value.

  Here, when each of the retardation plates 30 and 35 has an in-plane retardation Ro of 30 nm or more and 60 nm or less, when the black display of the liquid crystal display device is viewed from an oblique direction, more red light than blue light is present. Since it permeate | transmits, the pigment | dye which shows the maximum absorption wavelength in 560-630 nm is contained in an adhesive so that red light may be absorbed effectively. On the other hand, when each of the retardation films 30 and 35 has an in-plane retardation Ro of more than 60 nm and not more than 100 nm, blue light is transmitted more than red light, so that blue light is effectively absorbed. In order to achieve this, the pressure-sensitive adhesive contains a dye having a maximum absorption wavelength at 430 to 510 nm.

  As long as the pigment | dye used here shows a maximum absorption in the above specific wavelengths, a well-known pigment | dye can be used without a restriction | limiting. Specific examples include tetraazaporphyrin-based, porphyrin-based, cyanine-based, azo-based, pyromethene-based, squarylium-based, xanthene-based, and oxonol-based compounds. Examples of the dye exhibiting a maximum absorption wavelength at 560 to 630 nm include: “TAP-18” (trade name), which is a tetraazaporphyrin-based compound sold by Yamada Chemical Industries, Ltd., is also used as a dye having a maximum absorption wavelength at 430 to 510 nm, also from Yamada Chemical Industries, Ltd. "YRC-18" (trade name), which is a cyanine compound sold, can be mentioned respectively.

  As a method for incorporating the dye into the pressure-sensitive adhesive layer, a known appropriate method can be employed. Specifically, a dye is added to the pressure-sensitive adhesive composition as described above to obtain a dye-containing pressure-sensitive adhesive. The added concentration of the dye varies depending on the absorption wavelength range and extinction coefficient of the dye, the thickness and number of the pressure-sensitive adhesive layers, the type of the base resin constituting the pressure-sensitive adhesive, etc. Further, it may be appropriately selected from the range of about 1 ppm to 10,000 ppm. A method in which such a dye-containing pressure-sensitive adhesive composition is directly applied on a retardation plate and dried, or a dye-containing pressure-sensitive adhesive composition is applied on a separation film that has been subjected to a release treatment, and then dried. The pressure-sensitive adhesive layer can be formed by, for example, a method of sticking it on a phase difference plate.

  As described above, in the present invention, the adhesive layer 40 for attaching the light incident side retardation plate 30 to the liquid crystal cell 60 and the adhesive layer 45 for attaching the light emission side retardation plate 35 to the liquid crystal cell 60. At least one of them contains a dye exhibiting a maximum absorption wavelength at 560 to 630 nm or 430 to 510 nm for color shift correction. Hereinafter, this dye may be referred to as “color shift correction dye”. In addition to the color shift correction dye, at least one of the light incident side pressure-sensitive adhesive layer 40 and the light emission side pressure sensitive adhesive layer 45 further contains a toning dye or a near-infrared absorbing dye for color correction. May be.

  The toning dye is blended for the purpose of correcting the color balance of the display color due to the color shift correcting dye described above and neutralizing it. Such a toning dye may be a general one having absorption in the visible region, and the type and concentration thereof are correlated with the color shift correcting dye to be combined, the absorption wavelength range and extinction coefficient of the dye, and the pressure sensitive adhesive layer. What is necessary is just to select suitably by thickness etc. and it does not specifically limit. When a dye exhibiting the maximum absorption wavelength at 560 to 630 nm is used as the color shift correction dye, the toning dye preferably exhibits absorption in the wavelength range of 350 to 550 nm. When a dye exhibiting a maximum absorption wavelength at 430 to 510 nm is used as the color shift correction dye, the toning dye preferably exhibits absorption in the wavelength range of 550 to 700 nm. As a method of incorporating the toning dye into the pressure-sensitive adhesive, any method can be adopted as in the case of the color shift correction dye.

  The near-infrared absorbing dye is blended in order to absorb near-infrared rays emitted from the backlight of the liquid crystal display device and to eliminate adverse effects caused by the near-infrared rays. In recent years, with the increase in size of liquid crystal display devices, the amount of near-infrared light emitted particularly when the cold cathode fluorescent lamp constituting the backlight is turned on and off has increased, and cordless phones and remote devices that use near-infrared light around the device. It has been pointed out that it may cause malfunctions by acting on electronic devices such as controllers. In order to solve the problem caused by the near infrared rays, a near infrared absorbing dye is blended in the pressure-sensitive adhesive layer.

  The near-infrared absorbing dye may be any dye that exhibits a maximum absorption wavelength in the near-infrared region of 800 nm to 1,100 nm. For example, diimonium-based, phthalocyanine-based, naphthalocyanine-based, azo-based, polymethine-based, anthraquinone-based, pyrylium-based , Squarylium-based, triphenylmethane-based, cyanine-based, and aminium-based compounds. These pigments can be used alone or in combination of two or more. In addition, the type and concentration of near-infrared absorbing dyes vary depending on the absorption wavelength range and absorption coefficient of the dye, the thickness of the adhesive layer, etc., but there is little absorption in the visible light region, a significant decrease in visible light transmittance, It is preferable not to cause this change. As a method for incorporating the near-infrared absorbing dye into the pressure-sensitive adhesive layer, a known appropriate method can be employed as in the case of the color shift correcting dye.

  When blending the toning dye and / or near-infrared absorbing dye as described above, as described above, it may be contained in at least one of the light incident side pressure-sensitive adhesive layer 40 and the light emission side pressure sensitive adhesive layer 45, and color When a shift correction dye is contained in one pressure-sensitive adhesive layer, the same pressure-sensitive adhesive layer may contain a toning dye and / or a near-infrared absorbing dye, or a color shift correction dye may be contained. You may make a toning dye and / or a near-infrared absorption dye contain in the adhesive layer different from an adhesive layer. However, in consideration of the labor for blending the pigment, it is preferable to blend the toning pigment and / or the near-infrared absorbing pigment in the pressure-sensitive adhesive layer containing the color shift correcting pigment.

  Various stabilizers can be further added for the purpose of improving the stability of these dyes to light and heat.

  As described above, the retardation plate and the pressure-sensitive adhesive layer are laminated in this order on the polarizing plate to form the respective composite polarizing plates disposed on both sides of the liquid crystal cell, and 2 disposed above and below the liquid crystal cell. Of at least one of the composite polarizing plates, at least one pressure-sensitive adhesive layer contains a color shift correction dye exhibiting maximum absorption at a specific wavelength, thereby forming a set of composite polarizing plates according to the present invention. Specifically, in the set of composite polarizing plates composed of the light incident side composite polarizing plate 50 and the light emitting side composite polarizing plate 55 shown in FIG. 1, the pressure-sensitive adhesive layer 40 constituting one composite polarizing plate 50 and At least one of the pressure-sensitive adhesive layers 45 constituting the other composite polarizing plate 55 is made to contain a color shift correction dye exhibiting maximum absorption at a specific wavelength to form a set of composite polarizing plates.

  In the polarizing plate constituting the set of the liquid crystal display device or the composite polarizing plate of the present invention, another optical functional film may be attached to the surface of the transparent protective layer. As the optical functional film, for example, a film composed of a functional layer such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer as described above, or a property opposite to that of a certain kind of polarized light is transmitted. A reflective polarizing separation film that reflects polarized light, a reflective film having a reflective function on the surface, and a transflective film having both a reflective function and a transmissive function. A commercial product equivalent to a reflective polarized light separating film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties is sold by 3M Company in the US [Sumitomo 3M Limited in Japan]. “DBEF” (product name).

  The backlight 10 may be widely used in general liquid crystal display devices. For example, it is composed of a diffuser plate and a light source arranged behind it, and the light from the light source is uniformly diffused by the diffuser plate and then emitted to the front side, or a light guide plate And a light source placed on the side of the light source. Once the light from the light source is taken into the light guide plate, the light is uniformly emitted to the front side. And so on. As a light source in the backlight, a cold cathode fluorescent lamp that emits white light using a fluorescent tube, a light emitting diode (LED), or the like can be adopted. This is particularly effective when a lamp is used.

  The liquid crystal cell 40 is a device in which a liquid crystal is sealed between two transparent substrates in order to switch the amount of transmitted light, and has a function of changing the alignment state of the liquid crystal by applying a voltage. It may be widely used. The liquid crystal cell 40 typically includes at least a pair of transparent substrates disposed opposite to each other, a transparent electrode provided on each surface of the substrates, and a liquid crystal layer sealed between the electrodes. Have Depending on the alignment state of the liquid crystal layer enclosed in the liquid crystal cell and the alignment state of the liquid crystal layer when a voltage is applied between the electrodes, for example, a twisted nematic (TN) mode or a vertical alignment (VA) mode is used. There are various types.

  The configuration of the present invention is particularly effective for a vertical alignment (VA) mode liquid crystal cell. In the vertical alignment mode, rod-shaped liquid crystal molecules having positive or negative dielectric anisotropy are enclosed in a cell, and in the state where no voltage is applied, the major axis of the liquid crystal molecules is aligned perpendicular to the cell substrate. The major axis of liquid crystal molecules is rotated in a direction parallel to the cell substrate by applying a voltage, thereby switching the amount of transmitted light.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these examples.

The polarizer protective films and retardation plates used in the following examples are as follows, and are indicated by their respective symbols. The thickness, the in-plane retardation Ro and the thickness direction retardation Rth is the manufacturer nominal value, slow axis direction in-plane refractive index n _x, fast axis in-plane refractive index n _y and a thickness direction refractive index n _z is a value obtained with a phase difference measuring device “KOBRA-21ADH” manufactured by Oji Scientific Instruments. Note that Ro and Rth were actually measured using “KOBRA-21ADH”, but almost the same results as the following values were obtained. Further, n _x, n _y, the values from n _z and the thickness d is determined by the formula (1) and (2), but may not necessarily match the following Ro and Rth, which is a three-axial The main factors are that the refractive indices _nx , _ny and _nz are kept to the fourth decimal place.

(A) Triacetylcellulose film (transparent protective layer) with almost no in-plane retardation
TAC: Product name "KC8UX2M", obtained from Konica Minolta Opto,
Thickness 80μm.

(B) Retardation plate made of cellulose acetate resin film RAC1: Trade name “KC4FR-T”, obtained from Konica Minolta Opto,
Thickness 41 μm, Ro = 42 nm, Rth = 107 nm,
n _x = 1.4844, n _y = 1.4834, n _z = 1.4813.
RAC2: Trade name “KC4FR-T”, obtained from Konica Minolta Opto,
42 μm thickness, Ro = 61 nm, Rth = 130 nm,
n _x = 1.4848, n _y = 1.4833, n _z = 1.4809.
RAC1 and RAC2 were obtained by specifying in-plane retardation values, respectively.

(C) Retardation plate made of norbornene resin film COP1: Trade name “ZEONOR FILM”, obtained from Optes Co., Ltd.
Thickness 72 μm, Ro = 46 nm, Rth = 121 nm,
n _x = 1.5309, n _y = 1.5302, n _z = 1.5289.
COP2: Trade name "Zeonor Film", obtained from Optes Co., Ltd.
Thickness 73 μm, Ro = 70 nm, Rth = 123 nm,
_{n x = 1.5310, n y =} 1.5301, n z = 1.5289.
COP1 and COP2 were obtained by designating in-plane retardation values, respectively.

[Reference Example 1] Preparation of red light-absorbing dye-containing pressure-sensitive adhesive sheet A tetraazaporphyrin-based compound having a maximum absorption wavelength at 593 nm [Yamada Chemical Industries, Ltd.] Manufactured under the trade name "TAP-18"] was added at 400 ppm (based on the solid content weight of the pressure-sensitive adhesive composition) to prepare a dye-containing pressure-sensitive adhesive composition. This dye-containing pressure-sensitive adhesive composition was applied to a release-treated surface of a polyethylene terephthalate film (separated film) that had been subjected to a release treatment so that the thickness after drying would be 25 μm. A pressure-sensitive adhesive layer was formed by performing a drying treatment for 5 minutes. Then, the pigment | dye containing adhesive sheet was produced by bonding the same separate film as the above to the exposed surface of an adhesive.

[Reference Example 2] Preparation of blue light-absorbing dye-containing pressure-sensitive adhesive sheet Except that the dye was changed to a cyanine compound having a maximum absorption wavelength at 494 nm (trade name “YRC-18” manufactured by Yamada Chemical Co., Ltd.). In the same manner as in Reference Example 1, a dye-containing pressure-sensitive adhesive sheet was produced.

[Example 1]
(A) Preparation of composite polarizing plate with pressure-sensitive adhesive layer (a1) Composite polarizing plate with dye-containing pressure-sensitive adhesive layer Triacetyl surface-saponified on one side of a polarizer in which iodine is adsorbed and oriented on polyvinyl alcohol Cellulose film TAC is bonded to the other surface with retardation plate RAC1 made of cellulose acetate-based resin film, which has also been subjected to surface saponification treatment, via an adhesive made of an aqueous solution containing polyvinyl alcohol resin. Thus, a composite polarizing plate was produced. On the side of the retardation plate RAC1, the one obtained by peeling off the one-sided separate film from the adhesive sheet containing the dye having the maximum absorption wavelength at 593 nm prepared in Reference Example 1 is bonded to the adhesive side, and the dye-containing adhesive layer A composite polarizing plate was prepared.

(A2) Composite polarizing plate with dye-free pressure-sensitive adhesive layer On the other hand, an acrylic pressure-sensitive adhesive layer that does not contain a dye is provided on the retardation plate RAC1 side of the same three-layer composite polarizing plate of TAC / polarizer / RAC1. A pressure-sensitive adhesive sheet formed on a separate film was laminated to prepare a composite polarizing plate with a dye-free pressure-sensitive adhesive layer.

(B) Production of liquid crystal display device The polarizing plate is peeled off from the vertical alignment mode liquid crystal display device “BRAVIA” (diagonal dimension 40 inches = about 102 cm) manufactured by Sony Corporation. Instead, the above (a1 ) Was peeled off from the composite polarizing plate with the dye-containing pressure-sensitive adhesive layer, and was attached to the pressure-sensitive adhesive layer side in the same axial direction as the original polarizing plate. In addition, the light incident side polarizing plate is also peeled off, and instead of the separated polarizing film from the composite polarizing plate with the dye-free pressure-sensitive adhesive layer produced in (a2) above, the same axial direction as the original polarizing plate, It stuck on the adhesive layer side. In this way, a liquid crystal display device was prepared in which the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contained a dye having a maximum absorption wavelength at 593 nm.

[Comparative Example 1]
Except that both the light exit side polarizing plate and the light incident side polarizing plate are composite polarizing plates with a dye-free pressure-sensitive adhesive layer prepared in Example 1 (a2), the same as in Example 1 (b). Thus, a liquid crystal display device was produced.

[Comparative Example 2]
(A) Production of composite polarizing plate with dye-containing pressure-sensitive adhesive layer The maximum absorption wavelength at 494 nm produced in Reference Example 2 is applied to the retardation plate RAC1 side of the same composite polarizing plate produced in Example 1 (a1). What peeled off the one side separate film from the adhesive sheet containing the pigment | dye to show was bonded together on the adhesive side, and the composite polarizing plate with a pigment | dye containing adhesive layer was produced.

(B) Preparation of liquid crystal display device The light-exiting-side polarizing plate was changed to the composite polarizing plate with the dye-containing pressure-sensitive adhesive prepared in the above (a), and the light-incident side polarizing plate was the same as in Example 1, and the dye-free pressure-sensitive adhesive. A liquid crystal display device was produced in the same manner as in Example 1 (b) except that the composite polarizing plate had a layer. In this liquid crystal display device, the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contains a dye having a maximum absorption wavelength at 494 nm.

[Example 2]
(A) Preparation of composite polarizing plate with pressure-sensitive adhesive layer (a1) Composite polarizing plate with dye-containing pressure-sensitive adhesive layer Triacetyl surface-saponified on one side of a polarizer in which iodine is adsorbed and oriented on polyvinyl alcohol Cellulose film TAC is bonded to the other surface with a retardation plate COP1 made of a norbornene resin film having a corona treatment on the surface, via an adhesive made of a polyvinyl alcohol resin-containing aqueous solution. A composite polarizing plate was prepared. On the phase difference plate COP1 side, the one-side separate film is peeled off from the pressure-sensitive adhesive sheet containing the dye having the maximum absorption wavelength at 593 nm prepared in Reference Example 1, and the dye-containing pressure-sensitive adhesive is bonded to the pressure-sensitive adhesive side. A layered composite polarizing plate was prepared.

(A2) Composite polarizing plate with dye-free pressure-sensitive adhesive layer On the other hand, an acrylic pressure-sensitive adhesive layer containing no dye is present on the retardation plate COP1 side of the same three-layer composite polarizing plate of TAC / polarizer / COP1. A pressure-sensitive adhesive sheet formed on a separate film was laminated to prepare a composite polarizing plate with a dye-free pressure-sensitive adhesive layer.

(B) Production of liquid crystal display device The light emitting side polarizing plate was peeled off from the same liquid crystal display device “BRAVIA” used in (b) of Example 1, and instead, the dye-containing adhesive produced in (a1) above. What peeled off the separate film from the composite polarizing plate with an adhesive layer was affixed on the adhesive layer side in the same axial direction as the original polarizing plate. In addition, the light incident side polarizing plate is also peeled off, and instead of the composite polarizing plate with the dye-free pressure-sensitive adhesive layer prepared in (a2) above, the separation film is peeled off in the same axial direction as the original polarizing plate. It stuck on the adhesive layer side. In this way, a liquid crystal display device was prepared in which the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contained a dye having a maximum absorption wavelength at 593 nm.

[Comparative Example 3]
Except that both the light exit side polarizing plate and the light incident side polarizing plate are composite polarizing plates with a dye-free pressure-sensitive adhesive layer produced in (a2) of Example 2, the same as in (b) of Example 2 Thus, a liquid crystal display device was produced.

[Comparative Example 4]
(A) Preparation of composite polarizing plate with dye-containing pressure-sensitive adhesive layer The maximum absorption wavelength at 494 nm prepared in Reference Example 2 is formed on the retardation plate COP1 side of the same composite polarizing plate as prepared in (a1) of Example 2. What peeled off the one side separate film from the adhesive sheet containing the pigment | dye to show was bonded together on the adhesive side, and the composite polarizing plate with a pigment | dye containing adhesive layer was produced.

(B) Production of liquid crystal display device The light-exiting-side polarizing plate was changed to the composite polarizing plate with the dye-containing pressure-sensitive adhesive produced in (a), and the light-incident side polarizing plate was the same as in Example 2, and the dye-free pressure-sensitive adhesive. A liquid crystal display device was produced in the same manner as in Example 2 (b) except that the composite polarizing plate had a layer. In this liquid crystal display device, the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contains a dye having a maximum absorption wavelength at 494 nm.

[Evaluation of liquid crystal display devices]
For each of the liquid crystal display devices produced in Examples 1 and 2 and Comparative Examples 1 to 4 above, using a color luminance meter “SR-3A” manufactured by Topcon Technohouse Co., Ltd., the azimuth angle in the black display state ( CIE 1976 UCS Chromaticity coordinates measured from the viewing angle of φ = 45 ° and polar angle θ = 60 °, with the screen right direction set to 0 ° and rotated counterclockwise. Δu′v ′ was calculated from u ′ and v ′. Here, CIE 1976 UCS chromaticity coordinates are the u 'and v' coordinates that appear in the UCS-uniform-chlomaticity-scale (UCS) chromaticity diagram proposed by the Commission Internationale de l'Eclairage in 1976. . Δu′v ′ is expressed by the following equation (3), and is an index representing the deviation of the chromaticity from the white point, and U and V represent the u ′ coordinate and the v ′ coordinate at the white point, respectively. The smaller this value, the closer to the white point, and Δu′v ′ becomes zero at the white point.

  Table 1 summarizes the outline of the layer configuration and the test results in Examples 1 and 2 and Comparative Examples 1 to 4 described above. In the table, λmax means the maximum absorption wavelength.

These results, on both sides of the liquid crystal cell, n _x> n _y> n satisfy the relationship _z, if the in-plane retardation Ro is arranged relatively small phase difference plate and 42 nm, the liquid crystal cell retardation plate Example 1 in which a dye exhibiting a maximum absorption in a relatively long wavelength region of about 590 nm was contained in the pressure-sensitive adhesive layer for application to the adhesive layer was viewed obliquely in a black display state as compared with Comparative Example 1 containing no dye. In this case, the chromaticity was close to the white point, and the effect of reducing the color shift was recognized. On the other hand, in this configuration, in Comparative Example 2 in which the same pressure-sensitive adhesive layer as described above was incorporated with a dye exhibiting maximum absorption in a relatively short wavelength region of about 490 nm, the effect of reducing the color shift was not observed, but rather the dye was contained. The color shift was also increased compared to Comparative Example 1 that did not. In addition, the same tendency was observed between Example 2 and Comparative Examples 3 and 4 in which a retardation plate having an in-plane retardation Ro of 46 nm was disposed.

[Example 3]
(A) Preparation of composite polarizing plate with pressure-sensitive adhesive layer (a1) Composite polarizing plate with dye-containing pressure-sensitive adhesive layer Triacetyl surface-saponified on one side of a polarizer in which iodine is adsorbed and oriented on polyvinyl alcohol Cellulose film TAC is bonded to the other surface with retardation plate RAC2 made of cellulose acetate-based resin film, which is also subjected to surface saponification treatment, via an adhesive made of aqueous solution containing polyvinyl alcohol resin, respectively. Thus, a composite polarizing plate was produced. On the side of the retardation plate RAC2, the one obtained by peeling off the one-sided separate film from the adhesive sheet containing the dye having a maximum absorption wavelength at 494 nm prepared in Reference Example 2 is bonded to the adhesive side, and the dye-containing adhesive layer A composite polarizing plate was prepared.

(A2) Composite polarizing plate with a dye-free pressure-sensitive adhesive layer On the other hand, an acrylic pressure-sensitive adhesive layer containing no dye is present on the retardation plate RAC2 side of the same three-layered composite polarizing plate of TAC / polarizer / RAC2. A pressure-sensitive adhesive sheet formed on a separate film was laminated to prepare a composite polarizing plate with a dye-free pressure-sensitive adhesive layer.

(B) Production of liquid crystal display device The light emitting side polarizing plate was peeled off from the same liquid crystal display device “BRAVIA” used in (b) of Example 1, and instead, the dye-containing adhesive produced in (a1) above. What peeled off the separate film from the composite polarizing plate with an adhesive layer was affixed on the adhesive layer side in the same axial direction as the original polarizing plate. In addition, the light incident side polarizing plate is also peeled off, and instead of the separated polarizing film from the composite polarizing plate with the dye-free pressure-sensitive adhesive layer produced in (a2) above, the same axial direction as the original polarizing plate, It stuck on the adhesive layer side. In this way, a liquid crystal display device was prepared in which the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contained a dye having a maximum absorption wavelength at 494 nm.

[Comparative Example 5]
Except that both the light exit side polarizing plate and the light incident side polarizing plate are composite polarizing plates with a dye-free pressure-sensitive adhesive layer prepared in Example 3 (a2), the same as in Example 3 (b). Thus, a liquid crystal display device was produced.

[Comparative Example 6]
(A) Production of composite polarizing plate with dye-containing pressure-sensitive adhesive layer The maximum absorption wavelength at 593 nm produced in Reference Example 1 is applied to the retardation plate RAC2 side of the same composite polarizing plate produced in Example 3 (a1). What peeled off the one side separate film from the adhesive sheet containing the pigment | dye to show was bonded together on the adhesive side, and the composite polarizing plate with a pigment | dye containing adhesive layer was produced.

(B) Production of liquid crystal display device The light-exiting-side polarizing plate was changed to the composite-containing polarizing plate with the dye-containing pressure-sensitive adhesive produced in (a), and the light-incident side polarizing plate was a dye-free pressure-sensitive adhesive as in Example 3. A liquid crystal display device was produced in the same manner as in Example 3 (b) except that the composite polarizing plate had a layer. In this liquid crystal display device, the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contains a dye having a maximum absorption wavelength at 593 nm.

[Example 4]
(A) Preparation of composite polarizing plate with pressure-sensitive adhesive layer (a1) Composite polarizing plate with dye-containing pressure-sensitive adhesive layer Triacetyl surface-saponified on one side of a polarizer in which iodine is adsorbed and oriented on polyvinyl alcohol Cellulose film TAC is bonded to the other surface with a phase difference plate COP2 made of a norbornene-based resin film subjected to corona treatment on the surface via an adhesive made of a polyvinyl alcohol-based resin-containing aqueous solution. A composite polarizing plate was prepared. On the phase difference plate COP2 side, the one-side separate film is peeled off from the pressure-sensitive adhesive sheet containing the dye having a maximum absorption wavelength at 494 nm prepared in Reference Example 2, and the dye-containing pressure-sensitive adhesive is bonded to the pressure-sensitive adhesive side. A layered composite polarizing plate was prepared.

(A2) Composite polarizing plate with dye-free pressure-sensitive adhesive layer On the other hand, an acrylic pressure-sensitive adhesive layer containing no dye is present on the retardation plate COP2 side of the same three-layered polarizing plate of TAC / polarizer / COP2. A pressure-sensitive adhesive sheet formed on a separate film was laminated to prepare a composite polarizing plate with a dye-free pressure-sensitive adhesive layer.

(B) Production of liquid crystal display device The light emitting side polarizing plate was peeled off from the same liquid crystal display device “BRAVIA” used in (b) of Example 1, and instead, the dye-containing adhesive produced in (a1) above. What peeled off the separate film from the composite polarizing plate with an adhesive layer was affixed on the adhesive layer side in the same axial direction as the original polarizing plate. In addition, the light incident side polarizing plate is also peeled off, and instead of the composite polarizing plate with the dye-free pressure-sensitive adhesive layer prepared in (a2) above, the separation film is peeled off in the same axial direction as the original polarizing plate. It stuck on the adhesive layer side. In this way, a liquid crystal display device was prepared in which the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contained a dye having a maximum absorption wavelength at 494 nm.

[Comparative Example 7]
Except that both the light exit side polarizing plate and the light incident side polarizing plate are composite polarizing plates with a dye-free pressure-sensitive adhesive layer prepared in (a2) of Example 4, the same as in (b) of Example 4 Thus, a liquid crystal display device was produced.

[Comparative Example 8]
(A) Production of composite polarizing plate with dye-containing pressure-sensitive adhesive layer The maximum absorption wavelength at 593 nm produced in Reference Example 1 is formed on the retardation plate COP2 side of the same composite polarizing plate produced in Example 4 (a1). What peeled off the one side separate film from the adhesive sheet containing the pigment | dye to show was bonded together on the adhesive side, and the composite polarizing plate with a pigment | dye containing adhesive layer was produced.

(B) Production of liquid crystal display device The light exit side polarizing plate was changed to the composite polarizing plate with the dye-containing pressure-sensitive adhesive produced in the above (a), and the light incident side polarizing plate was the same as in Example 4, and the dye-free pressure-sensitive adhesive. A liquid crystal display device was produced in the same manner as in Example 4 (b) except that the composite polarizing plate had a layer. In this liquid crystal display device, the light emitting side pressure-sensitive adhesive layer of the liquid crystal cell contains a dye having a maximum absorption wavelength at 593 nm.

[Evaluation of liquid crystal display devices]
The liquid crystal display devices produced in Examples 3 and 4 and Comparative Examples 5 to 8 were evaluated in the same manner as in Examples 1 and 2 and Comparative Examples 1 to 4 described above. Table 2 summarizes the outline of the layer structure and the test results in these examples and comparative examples.

These results, on both sides of the liquid crystal cell, n _x> n _y> n satisfy the relationship _z, if the in-plane retardation Ro has placed a relatively large phase difference plate and 61 nm, the liquid crystal cell retardation plate Example 3 in which a dye exhibiting a maximum absorption in a relatively short wavelength region of around 490 nm was added to the pressure-sensitive adhesive layer to be attached to the surface of Example 3 was viewed obliquely in the black display state as compared with Comparative Example 5 containing no dye. In this case, the chromaticity was close to the white point, and the effect of reducing the color shift was recognized. On the other hand, in this configuration, in Comparative Example 6 in which the same pressure-sensitive adhesive layer as described above contains a dye exhibiting maximum absorption in a relatively long wavelength region of about 590 nm, the effect of reducing the color shift was not observed, but rather the dye was contained. Compared with Comparative Example 5 where no color shift was performed, the color shift was increased. The same tendency was also observed between Example 4 and Comparative Examples 7 and 8 in which a retardation plate having an in-plane retardation Ro of 70 nm was disposed.

It is a cross-sectional schematic diagram which shows the example of the fundamental layer structure of the liquid crystal display device which concerns on this invention.

Explanation of symbols

10 …… Backlight,
20. Light incident side polarizing plate,
21 …… Polarizer,
22 …… Transparent protective layer,
25: Light exit side polarizing plate,
26 …… Polarizer,
27 …… Transparent protective layer,
30: Light incident side retardation plate,
35 …… Light exit side phase difference plate,
40: Light incident side adhesive layer,
45 …… Light emitting side adhesive layer,
50: Light incident side composite polarizing plate,
55 …… Light-emission-side composite polarizing plate,
60: Liquid crystal cell.

Claims (16)

A liquid crystal display device in which a retardation plate and a polarizing plate are laminated in this order via adhesive layers on both sides of a liquid crystal cell, respectively, and a backlight is arranged on one side thereof,
Each two of the phase difference plate disposed on both sides of the liquid crystal cell, the slow axis direction of the in-plane refractive index n _x, the refractive index in a direction perpendicular to the slow axis in the plane n _y, the thickness direction the refractive index as n _z of, n _x> n _y> n satisfy the relationship _z, and whether in-plane retardation Ro are both located in the 60nm or less the range of 30 nm, or both range below 100nm exceeded 60nm And
At least one of the pressure-sensitive adhesive layers disposed on both sides of the liquid crystal cell contains a dye, and
When the two retardation plates each have an in-plane retardation Ro of 30 nm or more and 60 nm or less, the dye exhibits a maximum absorption wavelength at 560 to 630 nm,
In the case where each of the two retardation plates has an in-plane retardation Ro of more than 60 nm and not more than 100 nm, the dye exhibits a maximum absorption wavelength at 430 to 510 nm. apparatus.   Each of the two polarizing plates arranged on both sides of the liquid crystal cell has a structure in which a transparent protective layer is formed on one side of a polarizer made of polyvinyl alcohol resin, and the retardation is opposite to the transparent protective layer. The liquid crystal display device according to claim 1, wherein a plate is bonded.   The liquid crystal display device according to claim 1, wherein at least one of the two retardation plates disposed on both sides of the liquid crystal cell is made of a cyclic olefin resin film.   The liquid crystal display device according to claim 1, wherein at least one of the two retardation plates disposed on both sides of the liquid crystal cell is made of a cellulose acetate-based resin film.   3. The liquid crystal display device according to claim 1, wherein one of the two retardation plates disposed on both sides of the liquid crystal cell is made of a cellulose acetate resin film and the other is made of a cyclic olefin resin film.   The liquid crystal display device according to claim 4 or 5, wherein the cellulose acetate-based resin film constituting the retardation plate has a thickness of 20 to 100 µm.   The liquid crystal display device according to claim 1, wherein the pressure-sensitive adhesive layer containing a dye further contains a dye for color tone correction.   The liquid crystal display device according to claim 1, wherein the pressure-sensitive adhesive layer containing a dye further contains a near-infrared absorbing dye.   The liquid crystal display device according to claim 1, wherein the liquid crystal cell is in a vertical alignment mode. A set of composite polarizing plates arranged on both sides of the liquid crystal cell, in which a retardation plate and an adhesive layer are laminated in this order on each polarizing plate,
The retardation plate constituting the respective composite polarizing plate, a slow axis direction of the refractive index n _x in the plane, the refractive index in a direction perpendicular to the slow axis in the plane n _y, the refractive index in the thickness direction n _z satisfies the relationship of n _x > _ny > _nz , and both in- plane retardations Ro are in the range of 30 nm or more and 60 nm or less, or both are in the range of more than 60 nm and 100 nm or less,
At least one of the pressure-sensitive adhesive layers constituting each composite polarizing plate contains a dye, and
When the retardation plate constituting each composite polarizing plate has an in-plane retardation R o of 30 nm or more and 60 nm or less, the dye exhibits a maximum absorption wavelength at 560 to 630 nm,
When the retardation plate constituting each composite polarizing plate has an in-plane retardation Ro of more than 60 nm and not more than 100 nm, the dye exhibits a maximum absorption wavelength at 430 to 510 nm. A set of composite polarizing plates.   The polarizing plate constituting each composite polarizing plate has a structure in which a transparent protective layer is formed on one side of a polarizer made of polyvinyl alcohol resin, and the retardation plate is bonded to the opposite side of the transparent protective layer. The set of composite polarizing plates according to claim 10.   The set of composite polarizing plates according to claim 10 or 11, wherein at least one of the retardation plates constituting each composite polarizing plate is made of a cyclic olefin resin film.   The set of composite polarizing plates according to claim 10 or 11, wherein at least one of the retardation plates constituting each composite polarizing plate is made of a cellulose acetate-based resin film.   The set of composite polarizing plates according to claim 10 or 11, wherein one of the retardation plates constituting each composite polarizing plate is made of a cyclic olefin resin film and the other is made of a cellulose acetate resin film.   The set of composite polarizing plates according to any one of claims 10 to 14, wherein the pressure-sensitive adhesive layer containing a dye further contains a dye for color tone correction.   The set of composite polarizing plates according to any one of claims 10 to 14, wherein the pressure-sensitive adhesive layer containing a dye further contains a near-infrared absorbing dye.

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