JP2007264585A - Liquid crystal panel and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel which has an excellent display characteristic and can be made thin, and to provide a liquid crystal display device. <P>SOLUTION: The liquid crystal panel is provided with: a liquid crystal cell; a first optical compensation layer being a λ/4 plate which is arranged on one side of the liquid crystal cell and has a refractive index distribution of nx>ny=nz; a second optical compensation layer being a λ/2 plate having a refractive index distribution of nx>ny=nz and a first polarizer; a third optical compensation layer and a fourth optical compensation layer arranged on the other side of the liquid crystal cell; and a fifth optical compensation layer being a λ/2 plate having a refractive index distribution of nx>ny=nz and a second polarizer. The first optical compensation layer is a stretched film of a polymer film. Both of the second optical compensation layer and the fifth optical compensation layer are coating layers containing liquid crystal material. The third optical compensation layer is an inclined alignment layer of a material exhibiting optically negative uniaxiality. The fourth optical compensation layer has a refractive index distribution of nx>nz>ny. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal panel and a liquid crystal display device. More specifically, the present invention relates to a liquid crystal panel and a liquid crystal display device that have excellent display characteristics and can be thinned.

  As a display mode of the liquid crystal display device, various display modes are adopted depending on purposes. As typical examples, a vertical alignment (VA) mode, an electric field birefringence control (ECB) mode, an in-plane switching (IPS) mode, and the like are known. Currently, the VA mode is widely adopted due to advantages such as a simple configuration and excellent viewing angle characteristics.

The ECB mode is expected to be a display mode that can compete with the VA mode because it can display a multicolored color with a simple configuration and relatively stably. However, there is a problem that it is difficult to thin the ECB mode liquid crystal panel (as a result, a liquid crystal display device).
JP 2005-196043 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a liquid crystal panel and a liquid crystal display device (in particular, an ECB mode) that have excellent display characteristics and can be thinned. Liquid crystal panel and liquid crystal display device).

  The liquid crystal panel of the present invention includes a liquid crystal cell, and a first optical compensation layer that is a λ / 4 plate having a refractive index distribution of nx> ny = nz, which is disposed on one side of the liquid crystal cell, nx> ny = a second optical compensation layer and a first polarizer, which are λ / 2 plates having a refractive index distribution of nz, a third optical compensation layer disposed on the other side of the liquid crystal cell, and a fourth optical compensation A fifth optical compensation layer that is a λ / 2 plate having a refractive index profile of nx> ny = nz and a second polarizer. The first optical compensation layer is a stretched film of a polymer film. Both the second optical compensation layer and the fifth optical compensation layer are coating layers containing a liquid crystal material. The third optical compensation layer is a tilted alignment layer made of a material that exhibits optically negative uniaxiality. The fourth optical compensation layer has a refractive index distribution of nx> nz> ny.

  In a preferred embodiment, the liquid crystal cell is in an electric field controlled birefringence (ECB) mode.

  In a preferred embodiment, the thickness of the coating layer containing the liquid crystal material is 0.5 to 5 μm.

  In a preferred embodiment, the direction of the slow axis of the second optical compensation layer is 10 ° to 20 ° or −10 ° to −20 ° with respect to the direction of the absorption axis of the first polarizer. .

  In a preferred embodiment, the direction of the slow axis of the first optical compensation layer is 70 ° to 80 ° or −70 ° to −80 ° with respect to the direction of the absorption axis of the first polarizer. .

  According to another aspect of the present invention, a liquid crystal display device is provided. This liquid crystal display device includes the liquid crystal panel described above.

  As described above, according to the present invention, by combining optical compensation layers having predetermined optical characteristics, and forming a specific optical compensation layer of them from a liquid crystal material, very excellent display characteristics can be obtained. It is possible to provide a very thin liquid crystal panel (in particular, an ECB mode liquid crystal panel).

(Definition of terms and symbols)
Definitions of terms and symbols used herein are as follows:
(1) “nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction perpendicular to the slow axis in the plane (ie, fast phase) (Nz direction), and “nz” is the refractive index in the thickness direction. For example, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. In this specification, “substantially equal” is intended to include the case where nx and ny are different within a range that does not practically affect the overall polarization characteristics of the polarizing plate with an optical compensation layer.
(2) “In-plane retardation Re” refers to a retardation value in a film (layer) plane measured with light having a wavelength of 590 nm at 23 ° C. Re is the formula: Re = when the refractive index in the slow axis direction and the fast axis direction of the film (layer) at a wavelength of 590 nm is nx and ny, and d (nm) is the thickness of the film (layer). It is calculated by (nx−ny) × d.
(3) Thickness direction retardation Rth refers to a thickness direction retardation value measured at 23 ° C. with light having a wavelength of 590 nm. Rth is the formula: Rth = (nx) where the refractive index in the slow axis direction and the thickness direction of the film (layer) at a wavelength of 590 nm is nx and nz, and d (nm) is the thickness of the film (layer). -Nz) * d.
(4) The Nz coefficient is a ratio of Re and Rth, and is expressed by Nz = (nx−nz) / (nx−ny).
(5) “λ / 2 plate” refers to converting linearly polarized light having a specific vibration direction into linearly polarized light having a vibration direction orthogonal to the vibration direction of the linearly polarized light, or converting right circularly polarized light to the left circle It has a function of converting into polarized light (or converting left circularly polarized light into right circularly polarized light). The λ / 2 plate has a retardation value in the film (layer) plane of about ½ with respect to the wavelength of light (usually in the visible light region).
(6) “λ / 4 plate” means a plate having a function of converting linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The λ / 4 plate has a retardation value in the plane of the film (layer) of about ¼ with respect to the wavelength of light (usually in the visible light region).
(7) “Material that exhibits optically negative uniaxiality” refers to a material having a refractive index distribution such that the refractive index of the principal axis in one direction is smaller than the refractive indexes in the other two directions. Such a material has a refractive index profile such as nx = ny> nz.
(8) The “average optical axis” refers to the statistical average direction of the respective optical axes of material molecules that exhibit optically negative uniaxiality.
(9) Subscripts attached to terms and symbols described in this specification are, for example, “1” represents the first optical compensation layer, “2” represents the second optical compensation layer, and “ “3” represents a third optical compensation layer.
(10) Regarding the angle, the counterclockwise direction with respect to the long side is defined as “+”, and the clockwise direction is defined as “−”.

A. Liquid crystal panel A-1. 1 is a schematic sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. The liquid crystal panel 100 includes a liquid crystal cell 10, a first optical compensation layer 20, a second optical compensation layer 30, and a first polarizer 41 disposed on one side (viewing side in the illustrated example) of the liquid crystal cell 10. And a third optical compensation layer 50, a fourth optical compensation layer 60, a fifth optical compensation layer 70 and a second polarizer 42 disposed on the other side of the liquid crystal cell 10. If necessary, any appropriate protective layer may be disposed on at least one side of each polarizer (that is, the outermost side of the liquid crystal panel and / or the optical compensation layer side of the polarizer).

  Arbitrary appropriate arrangement orders can be adopted as the arrangement order of the respective optical compensation layers depending on the purpose, but the arrangement order as shown in FIG. 1 is preferable. This is because, when the optical compensation layer having such an arrangement order is combined with the ECB mode liquid crystal cell, a thin liquid crystal panel having very excellent display characteristics can be obtained. In the present invention, the first optical compensation layer 20 is a stretched polymer film. Both the second optical compensation layer 30 and the fifth optical compensation layer 70 are coating layers containing a liquid crystal material. The third optical compensation layer 50 is a tilted alignment layer made of a material that exhibits optically negative uniaxiality. The fourth optical compensation layer 60 has a refractive index distribution of nx> nz> ny. Details of each optical compensation layer will be described later.

  The liquid crystal cell 10 includes a pair of substrates (typically glass substrates and plastic substrates) 11 and 12 and a liquid crystal layer 13 as a display medium disposed between the substrates. One substrate (active matrix substrate) 12 includes a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the switching element, and a signal line for supplying a source signal. Provided (none shown). The other glass substrate (color filter substrate) 11 is provided with a color filter (not shown). The color filter may be provided on the active matrix substrate 12. A distance (cell gap) between the substrates 11 and 12 is controlled by a spacer 14. An alignment film (not shown) made of polyimide, for example, is provided on the side of the substrates 11 and 12 in contact with the liquid crystal layer 13.

  As a driving mode of the liquid crystal cell 10, any appropriate driving mode can be adopted as long as the effect of the present invention can be obtained. Preferably, the drive mode is an electric field controlled birefringence (ECB) mode. This is because, by combining with the overall configuration of the liquid crystal panel as described above, it is possible to achieve a significant reduction in thickness while maintaining excellent display characteristics.

  In the ECB mode, when no voltage is applied, the liquid crystal molecules in the liquid crystal cell are aligned in a predetermined direction, and when a voltage is applied, the liquid crystal molecules are inclined at a certain angle from the predetermined direction, thereby changing the polarization state due to the birefringence effect. I do. Further, in the ECB mode, the inclination of the liquid crystal molecules changes according to the magnitude of the applied voltage, and the transmitted light intensity changes according to the inclination. Therefore, when white light is incident, the light that has passed through the analyzer (the viewing-side polarizer) is colored by the interference phenomenon, and the hue changes according to the inclination (strength of the applied voltage) of the liquid crystal molecules. As a result, the ECB mode has an advantage that color display is possible with a simple configuration (for example, without providing a color filter). In the present invention, any suitable ECB mode can be adopted as long as it has the drive mechanism (display mechanism) as described above. Specific examples include a homeotropic (DAP: Deformation of Vertically Aligned Phases) system, a homogeneous system, and a hybrid (HAN: Hybrid Aligned Nematic) system. The outline of each method will be described below.

FIG. 2 is a schematic cross-sectional view for explaining the alignment state of liquid crystal molecules in the DAP method. As shown in FIG. 2A, the liquid crystal molecules are aligned perpendicular to the surfaces of the substrates 11 and 12 when no voltage is applied. Such vertical alignment can be realized by arranging a nematic liquid crystal (hereinafter referred to as Nn liquid crystal) having negative dielectric anisotropy between substrates on which a vertical alignment film (not shown) is formed. When light (linearly polarized light) that has passed through the second polarizer 42 is incident on the liquid crystal cell 10 when no voltage is applied, the incident light travels along the major axis direction of the vertically aligned liquid crystal molecules. Since no birefringence occurs in the major axis direction of the liquid crystal molecules, the incident light travels without changing the polarization direction and is absorbed by the first polarizer 41 having an absorption axis perpendicular to the second polarizer 42. This provides a dark display when no voltage is applied (normally black mode). On the other hand, as shown in FIG. 2B, when a voltage equal to or higher than the threshold is applied, the liquid crystal molecules are tilted by a certain angle ψ except for the liquid crystal molecules near the substrate. This angle ψ increases as the applied voltage increases. As a result, incident light (linearly polarized light) changes to elliptically polarized light, and a part of the light passes through the first polarizer (analyzer) 41. As shown in the following equation, the intensity I of the transmitted light depends on the applied voltage and depends on the wavelength of the incident light. Therefore, when the incident light is white light, the light passing through the first polarizer (analyzer) 41 is colored by the interference phenomenon, and its hue changes according to the strength of the applied voltage. In this way, color display is possible.
I = I ₀ sin ² θsin ² {πdΔn (V) / λ}
Here, I ₀ is the intensity of incident polarized light, θ is the angle between the incident polarization direction and the vibration direction of normal light in the cell, d is the thickness of the cell, Δn (V) is the birefringence at voltage V, and λ Is the wavelength of the incident light.

  FIG. 3 is a schematic cross-sectional view for explaining the alignment state of liquid crystal molecules in the homogeneous system. As shown in FIG. 3A, the liquid crystal molecules are aligned parallel to the surfaces of the substrates 11 and 12 when no voltage is applied. Such alignment can be realized by arranging nematic liquid crystal (hereinafter referred to as Np liquid crystal) having positive dielectric anisotropy between substrates on which an alignment film (not shown) is formed. On the other hand, as shown in FIG. 3B, when a voltage equal to or higher than the threshold is applied, the liquid crystal molecules are inclined by a certain angle ψ except for the liquid crystal molecules near the substrate. This angle ψ increases as the applied voltage increases. The homogeneous system performs display according to the same display principle as the DAP system except that the alignment state of liquid crystal molecules is reversed between when a voltage is applied and when no voltage is applied. Due to the difference in the alignment state of liquid crystal molecules, the homogeneous system has the following characteristics: (1) The order of the hue change of the interference color by voltage application is opposite to that of the DAP system, (2) Np liquid crystal Has a remarkably large dielectric anisotropy compared to the Nn liquid crystal, so the threshold voltage is smaller than that of the DAP method. (3) The hue change is clear compared to the DAP method.

FIG. 4 is a schematic cross-sectional view for explaining the alignment state of liquid crystal molecules in the HAN system. As shown in FIG. 4A, when no voltage is applied, the liquid crystal molecules are aligned parallel to the substrate in the vicinity of the substrate 12, and the angle of inclination with respect to the substrate increases along the thickness direction of the liquid crystal cell 10, In the vicinity of the substrate 11, it is oriented perpendicular to the substrate. Therefore, both Np liquid crystal and Nn liquid crystal can be used. The inclination θ of the liquid crystal molecules when a voltage is applied is represented by the sum of the initial elastic deformation θ ₀ and the dielectric deformation φ. When Np liquid crystal is used, the alignment state shown in FIG. 4B is taken. When Nn liquid crystal is used, the alignment state shown in FIG. 4C is taken. One of the performance characteristics of the HAN system is that there is no threshold voltage. This is because the elastic deformation θ ₀ already exists when no voltage is applied. As a result, the electro-optic effect occurs at a very low voltage.

B. First Optical Compensation Layer The first optical compensation layer 20 can function as a so-called λ / 4 plate. By correcting the wavelength dispersion characteristic of the first optical compensation layer functioning as the λ / 4 plate by the optical characteristic of the second optical compensation layer 30 functioning as the λ / 2 plate, the elliptical polarization function in a wide wavelength range Can be demonstrated. The in-plane retardation Re ₁ of such a first optical compensation layer is preferably 90 to 180 nm, more preferably 90 to 150 nm, and most preferably 105 to 135 nm. Furthermore, the first optical compensation layer 20 preferably has a refractive index distribution of nx> ny = nz.

  The first optical compensation layer 20 may be a stretched polymer film.

  Typical examples of the polymer constituting the polymer film include cyclic olefin resins and cellulose resins. Cyclic olefin resins are particularly preferred. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Examples of the norbornene-based monomer include norbornene, and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, etc., polar substituents such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like. It is done.

  In the present invention, other cycloolefins capable of ring-opening polymerization can be used in combination as long as the object of the present invention is not impaired. Specific examples of such cycloolefins include compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

  The cyclic olefin-based resin preferably has a number average molecular weight (Mn) measured by a gel permeation chromatograph (GPC) method using a toluene solvent, preferably 25,000 to 200,000, more preferably 30,000 to 100,000. 000, most preferably 40,000-80,000. When the number average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  When the cyclic olefin-based resin is obtained by hydrogenating a ring-opening polymer of a norbornene monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, Most preferably, it is 99% or more. Within such a range, the heat deterioration resistance and light deterioration resistance are excellent.

  As the cyclic olefin resin, various products are commercially available. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON Corporation, “ARTON” manufactured by JSR, “TOPAS” manufactured by TICONA, and “APEL” manufactured by Mitsui Chemicals, Inc. Is mentioned.

  Any appropriate cellulose resin (typically, an ester of cellulose and an acid) can be adopted as the cellulose resin. Preferred is an ester of cellulose and a fatty acid. Specific examples of such a cellulose resin include cellulose triacetate (triacetyl cellulose: TAC), cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Cellulose triacetate (triacetyl cellulose: TAC) is particularly preferred. This is because it has low birefringence and high transmittance. Many products are commercially available, and TAC is advantageous in terms of availability and cost.

  Specific examples of TAC commercial products are trade names “UV-50”, “UV-80”, “SH-50”, “SH-80”, “TD-80U”, “TD” manufactured by Fuji Photo Film Co., Ltd. -TAC "," UZ-TAC ", trade name" KC series "manufactured by Konica, and trade name" cellulose triacetate 80 [mu] m series "manufactured by Lonza Japan. Among these, “TD-80U” is preferable. This is because the transmittance and durability are excellent. “TD-80U” has excellent compatibility particularly in a TFT type liquid crystal display device.

  The first optical compensation layer can be obtained by stretching a polymer film. Preferably, it is obtained by stretching a film formed from the cyclic olefin resin or the cellulose resin. As a method for forming a polymer film, preferably, a method for forming a film from a cyclic olefin-based resin or a cellulose-based resin, any appropriate forming method can be adopted. Specific examples include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, casting method (casting) method and the like. An extrusion method or a casting method is preferred. This is because a film having high smoothness and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the characteristics desired for the optical compensation layer, and the like. In addition, since many film products are marketed for the said polymer film, Preferably the said cyclic olefin resin and the said cellulose resin, you may use the said commercial film as it is for a extending | stretching process.

  The stretching ratio of the film can vary depending on the in-plane retardation value and thickness desired for the optical compensation layer, the type of resin used, the thickness of the film used, the stretching temperature, and the like. Specifically, the draw ratio is preferably 1.3 to 2.3 times, more preferably 1.4 to 2.2 times, and most preferably 1.4 to 2.0 times. By stretching at such a magnification, an optical compensation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained. The stretching temperature of the film can also vary depending on the in-plane retardation value and thickness desired for the obtained optical compensation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably 130 to 155 ° C, more preferably 135 to 150 ° C, and most preferably 137 to 143 ° C. By stretching at such a temperature, an optical compensation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained. Examples of the stretching method include a longitudinal uniaxial stretching method and a lateral uniaxial stretching method.

  The thickness of the first optical compensation layer can be set so as to function most appropriately as a λ / 4 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. When the first optical compensation layer is a stretched film of a polymer film, the thickness is preferably 5 to 50 μm, more preferably 10 to 40 μm, and most preferably 20 to 35 μm.

C. Second optical compensation layer and fifth optical compensation layer C-1. Outline and Optical Properties of Second Optical Compensation Layer and Fifth Optical Compensation Layer Both the second optical compensation layer 30 and the fifth optical compensation layer 70 can function as a so-called λ / 2 plate. When the second optical compensation layer 30 functions as a λ / 2 plate, the wavelength dispersion characteristics of the first optical compensation layer 20 functioning as a λ / 4 plate (particularly, the wavelength range in which the phase difference deviates from λ / 4). The phase difference can be adjusted appropriately. Furthermore, when the fifth optical compensation layer 70 functions as a λ / 2 plate, elliptically polarized light can be generated in combination with the third optical compensation layer 50 and the fourth optical compensation layer 60. The in-plane retardations Re ₂ and Re ₅ of the second optical compensation layer are both preferably 240 to 300 nm, more preferably 250 to 290 nm, and most preferably 260 to 280 nm. Furthermore, both the second optical compensation layer 30 and the fifth optical compensation layer 70 preferably have a refractive index distribution of nx> ny = nz.

  In the liquid crystal panel of the present invention, both the second optical compensation layer 30 and the fifth optical compensation layer 70 are coating layers containing a liquid crystal material. By adopting such a configuration, the entire thickness of the liquid crystal panel can be reduced.

  The thicknesses of the second optical compensation layer and the fifth optical compensation layer can be set so as to function most appropriately as a λ / 2 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. The thickness of the second optical compensation layer and the fifth optical compensation layer is preferably 0.5 to 5 μm, more preferably 1 to 4 μm, and most preferably 1.5 to 3 μm.

C-2. Materials constituting the second optical compensation layer and the fifth optical compensation layer and methods for forming these layers C-2-1. Liquid Crystal Material Any appropriate liquid crystal material can be adopted as the liquid crystal material as long as the above-described characteristics are obtained. A liquid crystal material (nematic liquid crystal) in which the liquid crystal phase is a nematic phase is preferable. By using the liquid crystal material, the difference between nx and ny of the obtained optical compensation layer can be significantly increased as compared with the non-liquid crystal material. As a result, the thickness of the optical compensation layer for obtaining a desired in-plane retardation can be significantly reduced. As such a liquid crystal material, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystal material may exhibit a liquid crystallinity mechanism either lyotropic or thermotropic. The alignment state of the liquid crystal is preferably homogeneous alignment. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

  When the liquid crystal material is a liquid crystal monomer, for example, a polymerizable monomer and / or a crosslinkable monomer is preferable. This is because the alignment state of the liquid crystalline monomer can be fixed by polymerizing or crosslinking the liquid crystalline monomer, as will be described later. After aligning the liquid crystalline monomers, for example, if the liquid crystalline monomers are polymerized or crosslinked, the alignment state can be fixed thereby. Here, a polymer is formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Accordingly, in the formed first optical compensation layer, for example, a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change specific to the liquid crystal compound does not occur. As a result, the first optical compensation layer is an optical compensation layer with extremely high stability that is not affected by temperature changes.

  Any appropriate liquid crystal monomer can be adopted as the liquid crystal monomer. For example, polymerizable mesogenic compounds described in JP-T-2002-533742 (WO00 / 37585), EP358208 (US52111877), EP66137 (US4388453), WO93 / 22397, EP02661712, DE195504224, DE44081171, and GB2280445 can be used. Specific examples of such a polymerizable mesogenic compound include, for example, the trade name LC242 from BASF, the trade name E7 from Merck, and the trade name LC-Silicon-CC3767 from Wacker-Chem.

  Moreover, as a liquid crystal monomer, the liquid crystal monomer as described in Paragraph (0035)-(0046) of Unexamined-Japanese-Patent No. 2003-287623 can be illustrated preferably.

  The temperature range in which the liquid crystal monomer exhibits liquid crystal properties varies depending on the type. Specifically, the temperature range is preferably 40 to 120 ° C, more preferably 50 to 100 ° C, and most preferably 60 to 90 ° C.

C-2-2. Forming method of coating layer The coating layer of the liquid crystal material is formed by forming a coating film of a coating liquid in which the above liquid crystal material is dissolved or dispersed in an appropriate solvent, and then orienting the liquid crystal material in the coating film. Can be done. More specifically, the coating layer may be formed by subjecting the surface of an adjacent layer (for example, a protective layer laminated on a polarizer) to an orientation treatment and directly coating the surface with a coating solution. The coating layer may be formed on any appropriate base material that has been subjected to orientation treatment, and then transferred to the surface of a predetermined layer. The alignment of the liquid crystal material can be performed by heat treatment at a temperature at which the liquid crystal material exhibits a liquid crystal phase. By performing the heat treatment at a predetermined temperature, the liquid crystal material is aligned according to the direction of the applied alignment treatment. As a result, the direction of the slow axis (alignment direction of the liquid crystal material) of the resulting coating layer substantially matches the direction of the alignment treatment.

  Any appropriate alignment treatment can be adopted as the alignment treatment. Specifically, a mechanical alignment process, a physical alignment process, and a chemical alignment process are mentioned. Specific examples of the mechanical alignment treatment include rubbing treatment and stretching treatment. Specific examples of the physical alignment process include a magnetic field alignment process and an electric field alignment process. Specific examples of the chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. A rubbing process is preferred. In addition, arbitrary appropriate conditions may be employ | adopted for the process conditions of various orientation processes according to the objective.

  In the rubbing treatment step of rubbing the surface of the long substrate film with a rubbing roll, the rubbing treatment method preferably supports and conveys the long substrate film with a conveying belt having a metal surface, and A plurality of backup rolls are disposed so as to support the lower surface of the conveyance belt that supports the scale substrate film and face the rubbing roll, and the rubbing strength RS defined by the following formula (1) is preferably 800 mm or more, The method is more preferably set to 850 mm or more, further preferably 1000 mm or more, and particularly preferably 2200 mm or more.

  RS = N · M (1 + 2πr · nr / v) (1)

  Here, N is the number of rubbing times (number of rubbing rolls) (dimensionless amount), M is the pushing amount (mm) of the rubbing roll, π is the circumference, r is the radius (mm) of the rubbing roll, nr represents the number of rotations (rpm) of the rubbing roll, and v represents the conveyance speed (mm / sec) of the long base film. As will be described later, when a raised cloth is wound around the rubbing roll, r means the radius (mm) of the rubbing roll including the raised cloth portion.

  According to the above method, (1) when the rubbing treatment is performed, the amount of pushing of the rubbing roll is provided by disposing a plurality of backup rolls that support the lower surface of the conveying belt that supports and conveys the long base film. Can be rubbed in a stable state, even if it is increased (2) Even if the long base film is blocked, it is referred to as “rubbing strength”. It is possible to obtain uniform orientation characteristics (uniform optical characteristics) by setting the parameter value to a predetermined value or more. (3) Continuous rubbing treatment on a long base film by a roll-to-roll method Therefore, low cost can be realized. The “rubbing roll push-in amount” in the above method means that the rubbing roll first contacts the surface of the long base film when the position of the rubbing roll is changed with respect to the surface of the long base film. This position is the origin (0 point), which means the amount (position variation) of pushing the rubbing roll from the origin toward the long base film. As will be described later, when a raised cloth is wound around a rubbing roll, the position where the bristles of the raised cloth wound around the rubbing roll first contact the surface of the long base film is the origin (0 Point).

  In the rubbing treatment method, when the rubbing treatment is performed, a plurality of rod-shaped backup rolls supporting the lower surface of the conveying belt that supports and conveys the long base film is disposed substantially in parallel with each other, thereby The flatness of the conveyor belt supported by the roll is likely to increase. In this case, when the distance between adjacent backup rolls is set to be smaller than 50 mm, the external shape of the backup roll must be reduced. In this case, if the conveying speed of the long base film is constant, the backup roll will rotate at high speed during the rubbing process compared to the case where the outer diameter of the backup roll is large, and the heat generated at this time There is a possibility that problems such as deformation of the long base film supported by the conveyor belt may occur. On the other hand, when the distance between adjacent backup rolls is set to be larger than 90 mm, the flatness of the conveyor belt is lowered, thereby causing a problem of uneven orientation and an appearance defect. Therefore, in order to avoid such a problem, the distance between the axes of the adjacent backup rolls is preferably set to 50 mm or more and 90 mm or less, and more preferably set to 60 mm or more and 80 mm or less. According to this preferred configuration, it is possible to impart even more uniform orientation characteristics to the long base film, and thus, it is possible to form an optical compensation layer having even more uniform optical characteristics. .

  When the outer diameter (diameter) of the backup roll is set to be smaller than 30 mm, when the conveyance speed of the long base film is constant, the rubbing process is performed as compared with the case where the outer diameter of the backup roll is large. The backup roll rotates at a high speed, and the heat generated at this time may cause problems such as deformation of the long base film supported by the conveyor belt. On the other hand, when the outer diameter of the backup roll is set to be larger than 80 mm, there is a problem that orientation unevenness occurs due to a decrease in the flatness of the conveyor belt, and appearance defects tend to occur. Therefore, in order to avoid such a problem, the outer diameter of the backup roll is preferably set to 30 mm or more and 80 mm or less, and more preferably set to 40 mm or more and 70 mm or less.

  In the present invention, a brushed cloth is preferably wound around the rubbing roll. As the raised cloth, for example, any one of rayon, cotton, nylon, and a mixture thereof is preferably used.

  The thickness of the conveyor belt is preferably in the range of 0.5 to 2.0 mm, more preferably in the range of 0.7 to 1.5 mm in order to impart flexibility while preventing it from being easily slackened. is there.

  Hereinafter, an example of the rubbing method will be described with reference to the drawings.

  FIG. 7 is a perspective view showing a schematic configuration of a rubbing processing apparatus for carrying out the rubbing processing method. As shown in FIG. 7, the rubbing treatment apparatus includes a drive roll 1 and 2, an endless track conveyor belt 3 that is installed between the drive rolls 1 and 2 and supports and supports the long base film F; A rubbing roll 4 disposed so as to be vertically movable above and below the conveyor belt 3 and a lower surface of the conveyor belt 3 that supports the long base film F are supported and disposed so as to face the rubbing roll 4. A plurality (five in this example) of rod-like backup rolls 5 are provided. In addition, you may install an appropriate static elimination apparatus, a dust removal apparatus, etc. before and behind a rubbing processing apparatus as needed. In the present invention, the rubbing apparatus preferably has 2 to 6 backup rolls.

The conveyor belt 3 is a metal surface (the entire conveyor belt 3 may be made of metal) having a mirror-finished surface that supports the long base film F. As such a metal, various metal materials such as copper and steel can be used, but stainless steel is preferably used from the viewpoint of strength, hardness, and durability. In order to ensure adhesion with the long base film F, it is preferable to set the arithmetic average surface roughness Ra (JIS B 0601 (1994 version)) to 0.02 μm or less as the degree of mirror finish. Preferably it is 0.01 micrometer or less. Moreover, in order to prevent the slack of the long base film F, it is necessary to prevent the transport belt 3 that supports it from being slack. In view of the fact that it is necessary to give a certain degree of flexibility in order to prevent the conveyance belt 3 from slacking and to be installed between the drive rolls 1 and 2, the thickness of the conveyance belt 3 is 0.5-2. It is preferable to be in the range of 0.0 mm, and more preferably in the range of 0.7 to 1.5 mm. In addition, the tension applied to the conveyor belt 3 is preferably in the range of 0.5 to 20 kg weight / mm ² in consideration of the tension strength of the conveyor belt 3 while preventing the slack of the conveyor belt 3. Preferably, the range is ^{2 to} 15 kgf / mm ² .

  As for the rubbing roll 4, it is preferable that the raising cloth is wound by the outer peripheral surface. What is necessary is just to select suitably the material, shape, etc. of a raising cloth according to the material of the elongate base film F which is rubbed. Generally, rayon, cotton, nylon, or a mixture thereof can be applied as a raised cloth. The rotation axis of the rubbing roll 4 according to this example is inclined (for example, an inclination angle of 0 to 50 degrees) from a direction perpendicular to the conveyance direction of the long base film F (the direction indicated by the arrow in FIG. 7). That is, it can be set to an arbitrary axial angle with respect to the long side (longitudinal direction) of the long base film F. Moreover, the rotation direction of the rubbing roll 4 can be appropriately selected according to the conditions of the rubbing treatment.

  As described above, the plurality of backup rolls 5 are disposed so as to support the lower surface of the conveyance belt 3 that supports the long base film F and to face the rubbing roll 4. Since the plurality of backup rolls 5 are disposed, the rubbing roll 4 can be rubbed in a stable state even when the rubbing roll 4 is pushed in an inclined state or when the pushing amount of the rubbing roll 4 is increased. Processing can be performed.

  When the rubbing process is performed on the long base film F using the rubbing apparatus, the long base film F wound around a predetermined roll (not shown) has a plurality of transport rolls (not shown). Then, the toner is supplied onto the conveyor belt 3. And by rotating the drive rolls 1 and 2, the upper part of the transport belt 3 moves in the direction indicated by the arrow in FIG. 7, and accordingly, the long base film F is transported together with the transport belt 3, A rubbing process is performed by the rubbing roll 4.

  In the rubbing treatment step of this example, the rubbing strength RS defined by the following formula (1) is preferably set to 800 nm or more, more preferably 850 nm or more, further preferably 1000 nm or more, and particularly preferably 2200 nm or more. Yes.

  RS = N · M (1 + 2πr · nr / v) (1)

  8 is a front view partially showing the rubbing treatment apparatus shown in FIG. 7, FIG. 8 (a) is a front view of the vicinity of the rubbing roll 4, and FIG. 8 (b) is a rubbing roll 4 and a long base material. It is a front view which expands and shows the contact location vicinity with the film F surface. As described above, in the above formula (1), N is the number of rubbing times (corresponding to the number of rubbing rolls 4, 1 in this example) (dimensionless amount), and M is the pushing amount (mm) of the rubbing roll 4. , Π is the circumference, r is the radius (mm) of the rubbing roll 4 (including the raised cloth 4a), nr is the number of revolutions (rpm) of the rubbing roll, v is the conveyance speed of the long base film F (Mm / sec). Note that the pushing amount M of the rubbing roll is wound around the rubbing roll 4 when the position of the rubbing roll 4 is changed with respect to the surface of the long base film F as shown in FIG. The position at which the bristles of the raised cloth 4a first contact the surface of the long base film F (the position indicated by the broken line in FIG. 8B) is the origin (0 point), and the long base film F from the origin. Means the amount of pressing the rubbing roll 4 toward the position (the amount of pressing to the position indicated by the solid line in FIG. 8B).

  As described above, even when the rubbing strength RS is set to preferably 800 nm or more, more preferably 850 nm or more, further preferably 1000 nm or more, and particularly preferably 2200 nm or more, blocking occurs in the long base film F. Even so, uniform alignment characteristics can be imparted, and as a result, an optical compensation layer having uniform optical characteristics can be produced. The long base film F to which the rubbing treatment according to this example is applied is a liquid crystal compound applied to the surface by rubbing the surface or by rubbing an alignment film formed on the surface. As long as a function capable of orienting is provided, the material is not particularly limited, and the above-described long base film can be applied.

  In addition, as long as the rubbing strength RS is preferably set to 800 nm or more, more preferably 850 nm or more, further preferably 1000 nm or more, and particularly preferably 2200 nm or more, other rubbing treatment conditions (each parameter) can be arbitrarily selected. Yes, the conveyance speed v of the long base film F is, for example, preferably in the range of 1 to 50 m / min, more preferably in the range of 1 to 10 m / min, and the rotational speed nr of the rubbing roll 4 is, for example, The pushing amount M of the rubbing roll 4 is preferably in the range of 100 to 2000 μm, more preferably in the range of 100 to 1000 μm, for example.

  In this example, as a preferred configuration, for the plurality of rod-shaped backup rolls 5 arranged substantially parallel to each other, the distance between the axes of adjacent backup rolls 5 (L1 to L4 in FIG. 8A) is: Preferably, it is set to 50 mm or more and 90 mm or less, more preferably 60 mm or more and 80 mm or less. With such a configuration, the flatness of the transport belt 3 supported by the backup roll 5 is likely to increase. Further, since the inter-axis distances L1 to L4 are set to 50 mm or more (thus, the outer diameter of the backup roll 5 inevitably increases to some extent), the backup roll 5 does not rotate at high speed during the rubbing process. Due to the heat generated at this time, problems such as deformation of the long base film F supported by the conveyor belt 3 hardly occur. Furthermore, since the inter-axis distances L1 to L4 are set to 90 mm or less, the flatness of the transport belt 3 is not lowered, and uniform orientation characteristics can be imparted to the long base film F. The outer diameter of each backup roll 5 is preferably set to 30 mm to 80 mm, more preferably 40 mm to 70 mm. By setting the outer diameter of the backup roll 5 to 30 mm or more, the backup roll 5 does not rotate at high speed during the rubbing process, and the long base film F supported on the conveyor belt 3 by the heat generated at this time. Are unlikely to occur. In addition, by setting the outer diameter of the backup roll 5 to 80 mm or less, uniform orientation characteristics can be imparted to the long base film F without lowering the flatness of the transport belt 3. In this example, the case where the backup roll 5 is a rod-shaped roll has been described as an example. However, the present invention is not limited to this, and the backup roll 5 includes a plate (bearing plate) having a plurality of spherical bodies. ) Can also be applied.

  As described above, it is preferable that the treatment direction of the alignment treatment coincides with the direction of the slow axis of the coating layer. For example, when the second optical compensation layer is a coating layer, the direction of the alignment treatment is such that the slow axis direction of the second optical compensation layer is relative to the absorption axis direction of the first polarizer. Preferably 10 ° to 20 ° or −10 ° to −20 °, more preferably 12 ° to 18 ° or −12 ° to −18 °, most preferably 14 ° to 16 ° or −14 ° to −16 °. This is the direction.

  As the solvent, any suitable solvent that can dissolve or disperse the liquid crystal material can be adopted. The type of solvent used can be appropriately selected according to the type of liquid crystal material and the like. Specific examples of the solvent include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene, phenol, p-chlorophenol, and o-chlorophenol. , M-cresol, o-cresol, p-cresol and other phenols, benzene, toluene, xylene, mesitylene, methoxybenzene, 1,2-dimethoxybenzene and other aromatic hydrocarbons, acetone, methyl ethyl ketone (MEK), methyl Ketone solvents such as isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone and N-methyl-2-pyrrolidone, ester solvents such as ethyl acetate, butyl acetate and propyl acetate Alcohol solvents such as t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol, dimethylformamide, dimethyl Amide solvents such as acetamide, nitrile solvents such as acetonitrile and butyronitrile, ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane, or carbon disulfide, ethyl cellosolve, butyl cellosolve, ethyl cellosolve, etc. It is done. Preferred are toluene, xylene, mesitylene, MEK, methyl isobutyl ketone, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, and ethyl cellosolve. These solvents may be used alone or in combination of two or more.

  The content of the liquid crystal material in the coating liquid can be appropriately set according to the type of the liquid crystal material, the target layer thickness, and the like. Specifically, the content of the liquid crystal material is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, and most preferably 15 to 30% by weight.

  The said coating liquid can further contain arbitrary appropriate additives as needed. Specific examples of the additive include a polymerization initiator and a crosslinking agent. These are particularly preferably used when a liquid crystal monomer is used as the liquid crystal material. Specific examples of the polymerization initiator include benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN). Specific examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, metal chelate crosslinking agents, and the like. These may be used alone or in combination of two or more. Specific examples of other additives include anti-aging agents, modifiers, surfactants, dyes, pigments, anti-discoloring agents, and ultraviolet absorbers. These can also be used alone or in combination of two or more. Examples of the anti-aging agent include phenol compounds, amine compounds, organic sulfur compounds, and phosphine compounds. Examples of the modifier include glycols, silicones, and alcohols. The surfactant is used, for example, to smooth the surface of the optical film, and specific examples include silicone-based, acrylic-based, and fluorine-based surfactants.

The coating amount of the coating liquid can be appropriately set according to the concentration of the coating liquid, the thickness of the target layer, and the like. For example, when the concentration of the liquid crystal material in the coating liquid is 20% by weight, the coating amount is preferably 0.03 to 0.17 ml per unit area (100 cm ² ) of the surface of the layer to be coated. Preferably it is 0.05-0.15 ml, Most preferably, it is 0.08-0.12 ml.

  Any appropriate method can be adopted as the coating method. Specific examples include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, a curtain coating method, and a spray coating method.

  Next, the liquid crystal material is aligned. As described above, the alignment of the liquid crystal material is performed by processing at a temperature showing a liquid crystal phase, depending on the type of the liquid crystal material used. By performing such temperature treatment, the liquid crystal material takes a liquid crystal state, and the liquid crystal material is aligned according to the alignment treatment direction of the surface of the layer to be coated. Thereby, birefringence is generated in the layer formed by coating, and a predetermined optical compensation layer is formed.

  As described above, the treatment temperature can be appropriately determined according to the type of the liquid crystal material. Specifically, processing temperature becomes like this. Preferably it is 40-120 degreeC, More preferably, it is 50-100 degreeC, Most preferably, it is 60-90 degreeC. The treatment time is preferably 30 seconds or longer, more preferably 1 minute or longer, particularly preferably 2 minutes or longer, and most preferably 4 minutes or longer. When the treatment time is less than 30 seconds, the liquid crystal material may not take a sufficient liquid crystal state. On the other hand, the treatment time is preferably 10 minutes or less, more preferably 8 minutes or less, and most preferably 7 minutes or less. When processing time exceeds 10 minutes, there exists a possibility that an additive may sublime.

  Further, when a liquid crystal monomer is used as the liquid crystal material, it is preferable to further subject the layer formed by the coating to a polymerization treatment or a crosslinking treatment. By performing the polymerization treatment, the liquid crystal monomer is polymerized, and the liquid crystal monomer is fixed as a repeating unit of the polymer molecule. Further, by performing the crosslinking treatment, the liquid crystal monomer forms a three-dimensional network structure, and the liquid crystal monomer is fixed as a part of the crosslinked structure. As a result, the alignment state of the liquid crystal material is fixed. The polymer formed by polymerizing or crosslinking the liquid crystal monomer or the three-dimensional network structure is “non-liquid crystalline”. Therefore, the formed first optical compensation layer has, for example, a temperature change peculiar to liquid crystal molecules. No transition to liquid crystal phase, glass phase, or crystal phase occurs due to.

  The specific procedure of the above-mentioned polymerization treatment or crosslinking treatment can be appropriately selected depending on the kind of polymerization initiator and crosslinking agent used. For example, light irradiation may be performed when a photopolymerization initiator or a photocrosslinking agent is used, and ultraviolet irradiation may be performed when an ultraviolet polymerization initiator or an ultraviolet crosslinking agent is used. The irradiation time, irradiation intensity, total irradiation amount, etc. of light or ultraviolet rays are appropriately set according to the type of liquid crystal material, the type of transparent protective film and the type of alignment treatment, the characteristics desired for the obtained optical compensation layer, etc. obtain.

D. Third Optical Compensation Layer The third optical compensation layer 50 is a graded alignment layer made of a material that exhibits optically negative uniaxiality. By using the tilt alignment layer as the third optical compensation layer, liquid crystal that is not completely perpendicular to the ECB mode can be preferably compensated, and visual characteristics are improved. Specific examples of the optically negative uniaxial material include non-liquid crystal materials such as polyimide materials and liquid crystal materials such as discotic liquid crystal compounds. Furthermore, films containing these materials as main components, mixed and reacted with other polymers or oligomers, and fixed in a state in which materials exhibiting negative uniaxiality are tilted and oriented can be used. Liquid crystal materials are preferred, and discotic liquid crystal compounds are particularly preferred. When a discotic liquid crystal compound is used, the tilted alignment state is adjusted for the type and molecular structure of the discotic liquid crystal compound, the type of alignment film, additives (eg, plasticizer, binder, surfactant), etc. Can be controlled by

  The discotic liquid crystal compound generally has a cyclic mother nucleus such as benzene, 1,3,5-triazine, calixarene, etc. arranged at the center of the molecule, a linear alkyl group, alkoxy group, substituted A liquid crystal compound having a discotic molecular structure in which a benzoyloxy group or the like is radially substituted as its side chain. Typical examples of discotic liquid crystals include C.I. Destrade et al., Mol. Cryst. Liq. Cryst. 71, 111 (1981), benzene derivatives, triphenylene derivatives, truxene derivatives, phthalocyanine derivatives, B.I. Kohne et al., Angew. Chem. 96, page 70 (1984), and cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Soc. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), and azacrown and phenylacetylene macrocycles.

  In the present specification, “tilted alignment” means that molecules of a material (for example, a discotic liquid crystal compound) exhibiting optically negative uniaxiality in the third optical compensation layer are aligned with respect to the plane of the optical compensation layer. A state where they are lined up at an angle. In the tilted orientation state, the tilt angle of the molecule may change according to the thickness direction of the third optical compensation layer, or the tilt angle of the molecule may not change in the thickness direction and may be constant (tilt orientation). In the present invention, the angle formed between the optical axis of the optically negative uniaxial material and the normal direction of the third optical compensation layer increases as the fourth optical compensation layer 60 is approached. It is preferable that the maximum is at the interface between the third optical compensation layer 50 and the fourth optical compensation layer 60.

  The average optical axis of the optically negative uniaxial material in the third optical compensation layer is preferably 5 ° to 50 °, more preferably 10 with respect to the normal direction of the third optical compensation layer. It is inclined at an angle of from -30 °, most preferably from 15 ° to 25 °. By controlling the tilt angle to 5 ° or more, the viewing angle expansion effect is large when mounted on a liquid crystal display device or the like. By controlling the tilt angle to be 50 ° or less, the viewing angle characteristics are good in any of the four directions, up, down, left, and right, and it is possible to suppress the viewing angle characteristics from being improved or deteriorated depending on the viewing direction. .

The in-plane retardation Re ₃ of the third optical compensation layer as described above is preferably 0 to 200 nm, and more preferably 1 to 150 nm. Further, the phase difference Rth ₃ in the thickness direction is preferably 10 to 400 nm, more preferably from 50 to 300 nm.

  The thickness of the third optical compensation layer is not particularly limited, but is preferably 1 to 200 μm, more preferably 2 to 150 μm in the present invention.

E. Fourth optical compensation layer E-1. Optical Characteristics and Constituent Materials of Fourth Optical Compensation Layer The fourth optical compensation layer 60 has a refractive index distribution of nx>nz> ny. The in-plane retardation Re ₄ of the fourth optical compensation layer is preferably 240 to 350 nm, more preferably 240 nm to 300 nm, particularly preferably 260 to 280 nm, and most preferably 265 nm to 275 nm. By setting the in-plane retardation of the fourth optical compensation layer to about ½ of the visible wavelength, the contrast ratio in the oblique direction of the liquid crystal display device can be increased.

By using an optical compensation layer whose refractive index is controlled in the thickness direction as the fourth optical compensation layer, that is, by making the refractive index nz in the thickness direction larger than the in-plane minimum refractive index ny, Liquid crystals that are not perfectly vertical can be compensated favorably, and visual characteristics are improved. The thickness direction retardation Rth ₄ of the fourth optical compensation layer is preferably 35 to 190 nm, more preferably 90 to 190 nm, particularly preferably 100 to 165 nm, and most preferably 120 to 155 nm.

  The fourth optical compensation layer 60 can be made of any appropriate material as long as the above optical characteristics are satisfied. Preferably, the fourth optical compensation layer includes a retardation film containing a modified polycarbonate resin. More preferably, the fourth optical compensation layer includes a retardation film containing a styrene resin and a polycarbonate resin (hereinafter also referred to as a styrene / polycarbonate blend). The fourth optical compensation layer may be a retardation film containing a styrene / polycarbonate blend alone, or may be a laminate of two or more retardation films. A retardation film and another film (preferably May be a laminate with an isotropic film). Preferably, the fourth optical compensation layer is a single retardation film. This is because the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the backlight can be reduced, and the liquid crystal panel can be made thin. The retardation film as described above is typically a stretched polymer film. Hereinafter, for simplicity, the case where the fourth optical compensation layer is composed of a retardation film containing a styrene / polycarbonate blend will be described.

As for the photoelastic coefficient of the fourth optical compensation layer, an absolute value C [590] (m ² / N) of a value measured with light having a wavelength of 590 nm at 23 ° C. is preferably 2.0 × 10 ⁻¹¹ to 8. 0 × 10 ⁻¹¹ , more preferably 2.0 × 10 ^{−11 to} 6.0 × 10 ⁻¹¹ , particularly preferably 3.0 × 10 ^{−11 to} 6.0 × 10 ⁻¹¹ , most preferably from ^{4.0 × 10 -11 ~6.0 × 10 -11} . By setting it as such a range, the optical compensation layer which has the relationship of nx>nz> ny which cannot produce the shift | offset | difference and nonuniformity of the phase difference value by the shrinkage stress of a polarizer or the heat | fever of a backlight can be obtained. By using such a retardation film, display unevenness in the oblique direction of the liquid crystal display device can be remarkably improved.

  The thickness of the fourth optical compensation layer is preferably 10 to 200 μm, more preferably 15 to 150 μm, particularly preferably 40 to 100 μm, and most preferably 50 to 80 μm.

  The content of the styrenic resin in the styrene / polycarbonate blend is preferably 10 to 40 parts by weight, more preferably 20 to 40 parts by weight, particularly preferably 22 with respect to 100 parts by weight of the total solid content. It is -38 weight part, Most preferably, it is 25-35 weight part. Within the above range, an optical compensation layer having a sufficiently small photoelastic coefficient and a glass transition temperature suitable for durability, self-supporting property, stretchability, rigidity, and the like can be obtained. As a result, it is possible to obtain an optical compensation layer having a relationship of nx> nz> ny, which is unlikely to cause a shift or unevenness of a retardation value due to stress even when used in a liquid crystal display device.

  The styrene resin refers to a styrene polymer obtained by polymerizing a styrene monomer by any appropriate method. Specific examples of the styrene monomer include styrene, α-methylstyrene, 2,4-dimethylstyrene and the like. Commercially available styrene resins can also be used. Specific examples include styrene resins, acrylonitrile / styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / ethylene / styrene resins, styrene / maleimide copolymers, styrene / maleic anhydride copolymers, and the like. These may be used alone or in combination of two or more. Moreover, you may use together the said styrene-type resin and a styrene-type monomer.

  The weight average molecular weight (Mw) of the styrenic resin is preferably less than 20,000 in terms of polystyrene measured by GPC method using tetrahydrofuran as a developing solvent, and more preferably 1,000 to 10,000. Particularly preferred is 1,000 to 6,000, and most preferred is 1,000 to 3,000. If it is said range, a styrene-type resin and a polycarbonate-type resin will be mixed uniformly, and an optical compensation layer with high transparency can be obtained.

  As said polycarbonate-type resin, the aromatic polycarbonate which consists of an aromatic dihydric phenol component and a carbonate component is preferable. The aromatic polycarbonate can be usually obtained by a reaction between an aromatic dihydric phenol compound and a carbonate precursor. That is, an aromatic dihydric phenol compound is obtained by a phosgene method in which phosgene is blown in the presence of caustic alkali and a solvent, or a transesterification method in which an aromatic dihydric phenol compound and bisaryl carbonate are transesterified in the presence of a catalyst. Can do. Here, specific examples of the carbonate precursor include phosgene, bischloroformate of the above dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, di- A naphthyl carbonate etc. are mentioned. Phosgene and diphenyl carbonate are preferred.

  Specific examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxy). Phenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2 , 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5- And trimethylcyclohexane. These may be used alone or in combination of two or more. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are Used. In particular, it is preferable to use 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane in combination. By using these in combination, an optical compensation layer having a sufficiently low photoelastic coefficient and having an appropriate Tg and rigidity can be obtained.

  The polycarbonate resin using 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane as an aromatic dihydric phenol compound is The repeating unit represented by Formula (20) and (21) is included.

  As an aromatic dihydric phenol compound, when 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are used in combination, By changing the use ratio, the Tg and / or the photoelastic coefficient of the fourth optical compensation layer can be adjusted. For example, if the content of 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane in the polycarbonate-based resin is increased, Tg can be increased and the photoelastic coefficient can be decreased. The weight ratio of 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane in the polycarbonate-based resin is preferably from 2: 8 to 8: 2, more preferably 3: 7 to 6: 4, particularly preferably 3: 7 to 5: 5, and most preferably 4: 6. By using together at such a weight ratio, an optical compensation layer having a sufficiently low photoelastic coefficient and a glass transition temperature suitable for durability, self-supporting property, stretchability, rigidity and the like can be obtained.

  The weight-average molecular weight (Mw) of the polycarbonate resin is preferably 25,000 to 200,000 in terms of polystyrene measured by GPC method using tetrahydrofuran as a developing solvent, and more preferably 30,000 to 150,000. And particularly preferably 40,000 to 100,000, most preferably 50,000 to 80,000. By setting the weight average molecular weight of the polycarbonate resin in the above range, an optical compensation layer having excellent mechanical strength can be obtained.

  The difference in weight molecular weight (Mw) between the polycarbonate resin and the styrene resin (Mw of the polycarbonate resin−Mw of the styrene resin) is preferably 24,000 to 92,000, and more preferably 29,000. -87,000, particularly preferably 39,000-77,000, most preferably 49,000-67,000. Within the above range, an optical compensation layer having excellent mechanical strength and high transparency can be obtained.

  The fourth optical compensation layer can be obtained by, for example, pasting a shrinkable film on one or both sides of a polymer film containing a styrene / polycarbonate blend and heating and stretching the film by a longitudinal uniaxial stretching method using a roll stretching machine. . The shrinkable film is used for imparting a shrinkage force in a direction perpendicular to the stretching direction during heating and stretching, and increasing the refractive index in the thickness direction of the obtained retardation film. Any appropriate method can be adopted as a method of laminating the shrinkable film. For example, a method of providing and bonding an acrylic pressure-sensitive adhesive layer between the polymer film and the shrinkable film is preferable from the viewpoint of excellent productivity and workability.

E-2. Method for Forming Fourth Optical Compensation Layer An example of a method for forming the fourth optical compensation layer will be described with reference to FIG. FIG. 5 is a schematic view showing the concept of a typical method for forming the fourth optical compensation layer. For example, a polymer film 502 containing a styrene-based resin and a polycarbonate-based resin is fed out from the first feeding unit 501, and the second feeding unit 503 is placed on both surfaces of the polymer film 502 by laminating rolls 507 and 508. The shrinkable film 504 provided with the pressure-sensitive adhesive layer drawn out from the film and the shrinkable film 506 provided with the pressure-sensitive adhesive layer drawn out from the third payout part 505 are attached. A laminate in which a shrinkable film is adhered to both sides of a polymer film is applied with tension in the longitudinal direction of the film by rolls 510, 511, 512 and 513 having different speed ratios while being held at a constant temperature by a heating means 509. The film is subjected to a stretching treatment while being simultaneously given a tension in the thickness direction by the shrinkable film. In the 1st winding part 514 and the 2nd winding part 516, the shrinkable films 504 and 506 are peeled from the stretched laminate together with the pressure-sensitive adhesive layer, and a retardation film (stretched film) 518 is obtained. . If necessary, the obtained retardation film 518 is wound up by the third winding unit 519. This retardation film becomes the fourth optical compensation layer.

  The polymer film containing the styrene / polycarbonate blend can be typically obtained by a casting method or a melt extrusion method. Casting is preferred. This is because a retardation film having high smoothness and good optical uniformity can be obtained.

  As described above, the shrinkable film is used for imparting a shrinkage force in a direction perpendicular to the stretching direction at the time of heat stretching, and increasing the refractive index in the thickness direction of the obtained retardation film. Examples of the material used for the shrinkable film include polyester, polystyrene, polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene chloride. A polypropylene film is preferable from the viewpoint of excellent shrinkage uniformity and heat resistance.

  The shrinkable film is preferably a stretched film such as a biaxially stretched film or a uniaxially stretched film. The shrinkable film can be obtained, for example, by stretching an unstretched film formed into a sheet by an extrusion method in the longitudinal and / or transverse direction at a predetermined magnification with a simultaneous biaxial stretching machine or the like. The molding and stretching conditions can be appropriately selected according to the purpose, the composition or type of the resin used, and the like. A biaxially stretched polypropylene film is particularly preferred from the viewpoint of excellent shrinkage uniformity and heat resistance.

In one embodiment, the shrinkage ratio in the longitudinal direction of the shrinkable film at 140 ° C .: S ¹⁴⁰ (MD) is preferably 2.7 to 9.4%, and the shrinkage ratio in the width direction: S. ¹⁴⁰ (TD) is preferably 4.6 to 15.8%. In another embodiment, the shrinkage ratio in the longitudinal direction of the shrinkable film at 160 ° C .: S ¹⁶⁰ (MD) is preferably 13 to 23%, and the shrinkage ratio in the width direction: S ¹⁶⁰ (TD). Is preferably 30 to 48%. Within the above range, a retardation film having a desired retardation value and excellent in uniformity can be obtained.

  The stretching temperature when the polymer film containing the styrene / polycarbonate blend is stretched by heating is preferably equal to or higher than the glass transition temperature (Tg) of the polymer film. This is because the retardation value tends to be uniform and the resulting film is difficult to crystallize (white turbidity). The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. of the polymer film.

  The glass transition temperature (Tg) of the polymer film is preferably 110 to 185 ° C, more preferably 120 to 170 ° C, and particularly preferably 125 to 150 ° C. If Tg is 110 ° C. or higher, a film having good thermal stability can be easily obtained. If the temperature is 185 ° C. or lower, the in-plane and thickness direction retardation values can be easily controlled by stretching.

  The draw ratio when the polymer film is stretched by heating can be appropriately set according to the composition of the polymer film, the type of volatile component, the residual amount of volatile component, the desired retardation value, and the like. . The draw ratio is, for example, 1.05 to 2.00 times.

F. Polarizer Any appropriate polarizer may be adopted as each of the first polarizer 41 and the second polarizer 42 depending on the purpose. The first polarizer 41 and the second polarizer 42 may be the same or different. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of the polarizer is not particularly limited, but is generally about 1 to 80 μm.

  A polarizer uniaxially stretched by adsorbing iodine to a polyvinyl alcohol film can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing.

  By washing the polyvinyl alcohol film with water, not only can the surface of the polyvinyl alcohol film be cleaned and the anti-blocking agent can be washed, but also the effect of preventing unevenness such as uneven dyeing can be obtained by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

G. Protective layer Any appropriate film that can be used as a protective film for a polarizing plate can be adopted as the protective layer. Specific examples of the material that is the main component of such a film include cellulose resins such as triacetylcellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, Examples thereof include transparent resins such as polysulfone, polystyrene, polynorbornene, polyolefin, acrylic, and acetate. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition. TAC, polyimide resin, polyvinyl alcohol resin, and glassy polymer are preferable. Each protective layer may be the same or different.

  The protective layer is preferably transparent and has no color. Specifically, the thickness direction retardation value is preferably −90 nm to +90 nm, more preferably −80 nm to +80 nm, and most preferably −70 nm to +70 nm.

  As the thickness of the protective layer, any appropriate thickness can be adopted as long as the preferable thickness direction retardation is obtained. Specifically, the thickness of the protective layer is preferably 5 mm or less, more preferably 1 mm or less, particularly preferably 1 to 500 μm, and most preferably 5 to 150 μm.

H. Liquid Crystal Display Device FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. Although a transmissive liquid crystal display device is exemplified here, the present invention can be similarly applied to a reflective type and a transflective type. The liquid crystal display device 200 includes a liquid crystal panel 100 of the present invention, protective layers 110 and 110 ′ disposed on both sides of the liquid crystal panel 100, and surface treatment layers 120 and 120 disposed further outside the protective layers 110 and 110 ′. And a brightness enhancement film 130, a prism sheet 140, a light guide plate 150, and a lamp 160 disposed outside the surface treatment layer 120 ′ (backlight side in the illustrated example). When the protective layer described in the above section G is disposed outside the first polarizer 41 and the second polarizer 42, the protective layers 110 and 110 ′ can be omitted. The surface treatment layers 120 and 120 ′ are typically treatment layers subjected to hard coat treatment, antireflection treatment, sticking prevention treatment, diffusion treatment (also referred to as antiglare treatment), and the like. A representative example of the brightness enhancement film 130 is a polarization separation film having a polarization selection layer (eg, trade name “D-BEF series” manufactured by Sumitomo 3M Co., Ltd.). By appropriately using these optical members according to the purpose, a liquid crystal display device with higher display characteristics can be obtained. The optical member described in FIG. 6 is an exemplification, and as long as the effects of the present invention can be obtained, a part of the optical member may be omitted or replaced with another optical member.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples. The measuring method of each characteristic in an Example is as follows.

(1) Measurement of phase difference Refractive indexes nx, ny and nz of a sample film (optical compensation layer) are measured by an automatic birefringence measuring device (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA-WPR). The inner phase difference Re and the thickness direction phase difference Rth were calculated. The measurement temperature was 23 ° C. and the measurement wavelength was 590 nm.
(2) Measurement of thickness About the sample film (optical compensation layer) formed by coating, it measured by the interference film thickness measuring method using MCPD2000 made from Otsuka Electronics. The thicknesses of other sample films were measured using a dial gauge.

a. Preparation of Laminate Having First Optical Compensation Layer / Second Optical Compensation Layer / Protective Layer / Polarizer / Protective Layer Polarizing plate having a configuration of triacetyl cellulose (TAC) protective layer / polarizer / TAC protective layer ( Nitto Denko Corporation, trade name “SEG1425DU”) was prepared.

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name Paliocolor LC242, represented by the following formula (10)) and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by Ciba Specialty Chemicals: trade name) 3 g of Irgacure 907) was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

  The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth and subjected to orientation treatment. The conditions for the alignment treatment are as follows: rubbing frequency (number of rubbing rolls) is 1, rubbing roll radius r is 76.89 mm, rubbing roll rotation speed nr is 1500 rpm, film transport speed v is 83 mm / sec, rubbing strength RS and indentation amount M was performed under five conditions (a) to (e) as shown in Table 1.

The direction of the orientation treatment was set to a −75 ° direction when viewed from the viewing side with respect to the direction of the absorption axis of the polarizer when being attached to the polarizing plate. The above-mentioned coating liquid was applied to the alignment-treated surface with a bar coater, and the liquid crystal material was aligned by heating and drying at 90 ° C. for 2 minutes. Under conditions (a) to (c), the alignment state of the liquid crystal was very good. Under conditions (d) and (e), the liquid crystal alignment was slightly disturbed, but it was at a level causing no problem in practical use. The liquid crystal layer thus formed was irradiated with 1 mJ / cm ² of light using a metal halide lamp to cure the liquid crystal layer, thereby forming a second optical compensation layer on the PET film. The thickness of the second optical compensation layer was 2 μm, and the in-plane retardation Re ₂ was 270 nm. Furthermore, the second optical compensation layer had a refractive index distribution of nx> ny = nz.

  This second optical compensation layer was attached to the surface of the polarizing plate (manufactured by Nitto Denko Corporation, trade name “SEG1425DU”) using an isocyanate adhesive (thickness: 5 μm). Finally, the PET film was peeled off to obtain a laminate having the second optical compensation layer / protective layer / polarizer / protective layer.

A first optical compensation layer was produced by uniaxially stretching a norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd .: trade name ZEONOR: thickness 60 μm) at 140 ° C. to 1.32 times. The thickness of the first optical compensation layer was 54 μm, and the in-plane retardation Re ₁ was 140 nm. Further, the first optical compensation layer had a refractive index distribution of nx> ny = nz.

  This first optical compensation layer is made of an isocyanate-based adhesive so that the slow axis of the first optical compensation layer is -15 ° when viewed from the viewing side with respect to the direction of the absorption axis of the polarizer. It was affixed on the surface of the second optical compensation layer using (thickness 5 μm). In this manner, a laminate A having the first optical compensation layer / second optical compensation layer / protective layer / polarizer / protective layer was obtained.

b. Production of Laminate Having Third Optical Compensation Layer / Fourth Optical Compensation Layer / Fifth Optical Compensation Layer / Protective Layer / Polarizer / Protective Layer As a third optical compensation layer film, a supporting substrate and a liquid crystal A composite film (manufactured by Fuji Photo Film Co., Ltd., WVSA12B: thickness 110 μm) was used. In this composite film, a discotic liquid crystal tilt alignment layer is provided on a TAC support substrate. The in-plane retardation Re ₃ of this composite film was 30 nm, the thickness direction retardation Rth ₃ was 160 nm, and the inclination angle of the average optical axis was 20 °.

A biaxially stretched polypropylene film [trade name “Trephan” (thickness: 60 μm) manufactured by Toray] was bonded to both sides of a polycarbonate film (thickness: 58 μm) via an acrylic pressure-sensitive adhesive layer (thickness: 15 μm). Thereafter, the longitudinal direction of the film is held with a roll stretching machine, and the film is stretched 1.27 times in an air circulation type thermostatic oven at 147 ° C., and the biaxially stretched polypropylene film is peeled off together with the pressure-sensitive adhesive layer. An optical compensation layer was obtained. The thickness of the fourth optical compensation layer was 64 μm, the in-plane retardation Re ₄ was 270 nm, the thickness direction retardation Rth ₄ was 132 nm, and the Nz coefficient was 0.49. In addition, ^S140 (MD) of a biaxially stretched polypropylene film is 5.7%, ^S140 (TD) is 7.6%, ^S160 (MD) is 18.0%, and ^S160 (TD) is 35.7. %Met.

  The liquid crystal layer of the third optical compensation layer composite film and the fourth optical compensation layer are aligned with the direction of the slow axis, and are bonded using an isocyanate-based adhesive (thickness 5 μm), A laminate C was obtained.

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed with a rubbing cloth and subjected to orientation treatment. The direction of the orientation treatment was set to a −15 ° direction when viewed from the viewing side with respect to the direction of the absorption axis of the polarizer when pasted to the polarizing plate. A liquid crystal coating liquid similar to that described above was applied to the alignment-treated surface, and the liquid crystal was aligned and cured in the same manner as described above to form a fifth optical compensation layer on the PET film. The thickness of the fifth optical compensation layer was 2 μm, and the in-plane retardation Re ₅ was 270 nm. Further, the fifth optical compensation layer had a refractive index distribution of nx> ny = nz. The fifth optical compensation layer was attached to the surface of the fourth optical compensation layer using an isocyanate adhesive (thickness 5 μm), and then the PET film was peeled off. A polarizing plate (manufactured by Nitto Denko Corporation, trade name) having a structure of a TAC protective layer / a polarizer / TAC protective layer via an acrylic pressure-sensitive adhesive (thickness: 12 μm) on the fifth optical compensation layer of the obtained laminate. "SEG1425DU") was pasted together. In this way, a laminate B having the third optical compensation layer / the fourth optical compensation layer / the fifth optical compensation layer / the protective layer / the polarizer / the protective layer was obtained.

c. Preparation of Liquid Crystal Panel A liquid crystal cell was taken out from a liquid crystal display device (trade name i-pod, manufactured by Apple Computer) including an ECB mode (DAP type) liquid crystal cell, and the glass substrate surfaces above and below the surface were washed. The laminate A was attached to one glass substrate surface (viewing side) of the liquid crystal cell via an acrylic pressure-sensitive adhesive (thickness: 12 μm). The absorption axis of the polarizer of the laminate A was 150 ° when viewed from the viewing side with respect to the long side of the liquid crystal cell. At this time, it stuck so that a protective layer might become the outermost layer. Furthermore, the said laminated body B was affixed on the other glass substrate surface (backlight side) through the acrylic adhesive (thickness 12 micrometers). The absorption axis of the polarizer of the laminate B was 30 ° when viewed from the viewing side with respect to the long side of the liquid crystal cell. At this time, it stuck so that a protective layer might become the outermost layer. Furthermore, the laminate A was bonded so that the absorption axis of the polarizer of the laminate A and the absorption axis of the polarizer of the laminate B were orthogonal to each other. Thus, a liquid crystal panel (1) as shown in FIG. 1 was produced.

  The liquid crystal panel of the present invention can be suitably used for liquid crystal display devices such as personal computers, liquid crystal televisions, mobile phones, and personal digital assistants (PDAs).

It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment of this invention. It is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule in a DAP type liquid crystal cell. It is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule in a homogeneous type liquid crystal cell. It is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule in a HAN liquid crystal cell. It is a schematic diagram which shows the concept of the typical formation method of a 4th optical compensation layer. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It is a perspective view which shows schematic structure of a rubbing processing apparatus. FIG. 8A is a front view of the vicinity of the rubbing roll, and FIG. 8B is an enlarged front view of the vicinity of the contact portion between the rubbing roll and the long base film surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Drive roll 3 Conveyor belt 4 Rubbing roll 4a Brushed cloth 5 Backup roll F Long base film 10 Liquid crystal cell 20 1st optical compensation layer 30 2nd optical compensation layer 41 1st polarizer 42 2nd Polarizer 50 Third optical compensation layer 60 Fourth optical compensation layer 70 Fifth optical compensation layer 100 Liquid crystal panel 400 Liquid crystal display device

Claims (6)

A liquid crystal cell, and a first optical compensation layer which is a λ / 4 plate having a refractive index distribution of nx> ny = nz, disposed on one side of the liquid crystal cell, and having a refractive index distribution of nx> ny = nz a second optical compensation layer and a first polarizer which are λ / 2 plates, a third optical compensation layer and a fourth optical compensation layer disposed on the other side of the liquid crystal cell, nx> ny = nz A fifth optical compensation layer which is a λ / 2 plate having a refractive index distribution and a second polarizer,
The first optical compensation layer is a stretched film of a polymer film;
Both the second optical compensation layer and the fifth optical compensation layer are coating layers comprising a liquid crystal material;
The third optical compensation layer is an inclined alignment layer of a material exhibiting optically negative uniaxiality;
The liquid crystal panel, wherein the fourth optical compensation layer has a refractive index distribution of nx>nz> ny.   The liquid crystal panel according to claim 1, wherein the liquid crystal cell is in an electric field controlled birefringence (ECB) mode.   The liquid crystal panel according to claim 1, wherein the coating layer containing the liquid crystal material has a thickness of 0.5 to 5 μm.   The direction of the slow axis of the second optical compensation layer is 10 ° to 20 ° or −10 ° to −20 ° with respect to the direction of the absorption axis of the first polarizer. A liquid crystal panel according to any one of the above.   The direction of the slow axis of the first optical compensation layer is 70 ° to 80 ° or −70 ° to −80 ° with respect to the direction of the absorption axis of the first polarizer. A liquid crystal panel according to any one of the above. A liquid crystal display device comprising the liquid crystal panel according to claim 1.

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