JP2006171103A - Laminated optical film, polarizing plate with optical compensation function, image display device, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film capable of suppressing the coloring of a display image and displaying an image having a slight amount of gradation-inverted region even when a display image is seen from the oblique direction with respect to the normal direction of a screen. <P>SOLUTION: The laminated optical film is constituted by laminating: an optical film (1) in which the coefficient Nz expressed by the relation, Nz=(nx<SB>1</SB>-nz<SB>1</SB>)/(nx<SB>1</SB>-ny<SB>1</SB>), satisfies the relation, 0≤Nz≤1, when the direction allowing a refractive index in the film surface to be maximum is X-axis, the direction vertical to X-axis is Y-axis, the thickness direction of the film is Z-axis and refractive indexes in respective axial directions are nx<SB>1</SB>, ny<SB>1</SB>, nz<SB>1</SB>; an optical film (2) which is made of a material exhibiting optically negative uniaxial property and comprises a part made by obliquely aligning the material; and an optical film (3) which satisfies the relation, nx<SB>3</SB>≥ny<SB>3</SB>>nz<SB>3</SB>, when the direction allowing a refractive index in the film surface to be maximum is X-axis, the direction vertical to X-axis is Y-axis, the thickness direction of the film is Z-axis and the refractive indexes in respective axial directions are nx<SB>3</SB>, ny<SB>3</SB>, nz<SB>3</SB>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated optical film. The laminated optical film of the present invention can be used as various optical films such as a phase difference plate, an optical compensation film, a polarizing plate with an optical compensation function, a brightness enhancement film, alone or in combination with other optical films. In particular, the laminated optical film of the present invention is useful when laminated with a polarizer and used as a polarizing plate with an optical compensation function. The present invention also relates to a liquid crystal display device using the laminated optical film, a polarizing plate with an optical compensation function, and the like, an organic EL (electroluminescence) display device, and an image display device such as a PDP. As described above, the laminated optical film, the polarizing plate with an optical compensation function, and the like of the present invention can be applied to various liquid crystal display devices and the like, and among the liquid crystal display devices, they are particularly suitably used for OCB mode liquid crystal display devices.

Conventionally, in a liquid crystal display device or the like, a retardation plate is preferably used to obtain a wide viewing angle. As such a phase difference plate, a laminated film is proposed in which a plurality of polymer films having optical anisotropy are laminated with their optical axes crossed. In these laminated films, wide viewing angles are realized by intersecting the optical axes of two or more stretched films (see, for example, Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). Even when the retardation plate having the configuration of Patent Documents 1 to 4 described above is used, there is a problem that compensation other than the front and easy axis directions is insufficient, and these methods cannot obtain high contrast. .
JP-A-5-100114 JP-A-10-68816 JP-A-10-90521 JP 2004-233972 A

  The present invention provides an optical film that can suppress the coloring of a display image even when the display image is viewed from an oblique direction with respect to the normal direction of the screen and can display an image with a small gradation inversion region. The purpose is to provide.

  Moreover, an object of this invention is to provide the polarizing plate with an optical compensation function which laminated | stacked the said optical film and the polarizer. Furthermore, an object of the present invention is to provide an image display device using the optical film and a polarizing plate with an optical compensation function. Furthermore, an object of the present invention is to provide a liquid crystal display device using the optical film and a polarizing plate with an optical compensation function.

  The inventors of the present invention have intensively studied to solve the above-mentioned problems. As a result, they have found that the object can be achieved by using the following laminated optical film, and have completed the present invention.

That is, according to the present invention, the direction in which the in-plane refractive index is maximum is the X-axis, the direction perpendicular to the X-axis is the Y-axis, the thickness direction of the film is the Z-axis, and the refractive index in each axial direction is nx _1. , Ny ₁ , nz ₁ ,
Nz = with _{(nx 1 -nz 1) / (} nx 1 -ny 1) Nz coefficient expressed by the, 0 ≦ Nz ≦ 1, the optical film (1) which satisfies the,
An optical film (2) that is formed of a material exhibiting optically negative uniaxiality and includes a portion where the material is inclined and oriented;
The direction in which the refractive index in the film plane is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis, and the refractive indexes in the respective axial directions are nx ₃ , ny ₃ , nz If _{the 3} and the, the optical film (3) that satisfies nx ₃ ≧ ny _3> nz _3, the laminated optical film characterized by being laminated relates.

  The laminated optical film of the present invention is formed by laminating an optical film (1), an optical film (2) obtained by obliquely orienting an optically negative uniaxial material, and an optical film (3). It is useful as a phase difference plate that compensates for a wide viewing angle. An image display device such as a liquid crystal display device to which the laminated optical film is applied can achieve a wide viewing angle, and even when the display screen is viewed from an oblique direction, display coloration is suppressed, and a gradation inversion region is provided. Fewer images can be displayed.

  In the optical film (1), the Nz coefficient defined above is 0 ≦ Nz ≦ 1. When the Nz coefficient is Nz <0 or Nz> 1, it is difficult to realize a wide viewing angle, and the display coloring when the display screen is viewed from an oblique direction cannot be sufficiently suppressed. Gradation inversion in which the contrast from is reversed can occur. The Nz coefficient is, for example, Nz = 0.5 when one optical film (1) is used for compensation of the OCB mode liquid crystal cell (one laminated optical film on the viewing side or backlight side of the liquid crystal cell). It is preferably ± 0.05. On the other hand, when two optical films (1) (one each as a laminated optical film on the viewing side and the backlight side of the liquid crystal cell) are used for compensation of the liquid crystal cell in the OCB mode, the optical film on the one side (1 ) Is preferably combined with Nz = 0.25 ± 0.05, and the optical film (1) on the other side is preferably combined with Nz = 0.75 ± 0.05. Any of the optical films (1) having the Nz coefficient may be on the viewing side or on the backlight side.

  In the laminated optical film, the material that forms the optical film (2) and exhibits optically negative uniaxiality is preferably a discotic liquid crystal compound. A material that exhibits optically negative uniaxiality is not particularly limited, but a discotic liquid crystal compound is preferable because it is easy to control the tilt alignment and is a general material and relatively inexpensive.

  In the laminated optical film, the material that forms the optical film (2) and exhibits optically negative uniaxiality has an inclination angle between the average optical axis and the normal direction of the optical film (2) of 5 ° to 5 °. It is preferable to include a portion that is inclined and oriented within a range of 50 °.

  As described above, the optical film (2) is used as a laminated optical film combined with the optical film (1) and the optical film (3), but the inclination angle of the optical film (2) is controlled to 5 ° or more. Therefore, the effect of widening the viewing angle when mounted on a liquid crystal display device or the like is great. On the other hand, by controlling the tilt angle to be 50 ° or less, the viewing angle is good in any direction (four directions) up, down, left and right, and the viewing angle may be improved or worsened depending on the direction. Can be suppressed. From this viewpoint, the tilt angle is preferably 30 ° to 45 °.

  It should be noted that the optically negative optical material (for example, discotic liquid crystalline molecules) may have a uniform tilt (tilt) orientation that does not change with distance from the film plane. It may change with the distance between the material and the film plane.

  In the laminated optical film, the angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (3) is preferably 80 ° to 100 °. An image display device such as a liquid crystal display device using a laminated optical film in which the angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (3) is controlled within the above range can achieve a wider viewing angle. It is preferable because display coloring when the display screen is viewed from an oblique direction can be suppressed, and an image with a small gradation inversion region can be displayed.

  In the laminated optical film, the angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (1) is preferably 35 ° to 55 °. An image display device such as a liquid crystal display device using a laminated optical film in which the angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (1) is controlled within the above range can achieve a wider viewing angle. It is preferable that display coloring when the display screen is viewed from an oblique direction can be suppressed and an image with a small gradation inversion region can be displayed.

  The present invention also relates to a polarizing plate with an optical compensation function, wherein the laminated optical film and a polarizer are laminated.

  In the polarizing plate with an optical compensation function, the angle formed by the alignment axis of the optical film (2) and the absorption axis of the polarizer is preferably 35 ° to 55 °. An image display device such as a liquid crystal display device using a polarizing plate with an optical compensation function in which the angle formed by the alignment axis of the optical film (2) and the absorption axis of the polarizer is controlled within the above range can achieve a wider viewing angle. This is preferable in that display coloring when the display screen is viewed from an oblique direction can be suppressed, and an image with a small gradation inversion region can be displayed.

  The present invention also relates to an image display device in which the laminated optical film or the polarizing plate with an optical compensation function is laminated.

  Furthermore, the present invention relates to a liquid crystal display device in which the laminated optical film or the polarizing plate with an optical compensation function is laminated.

  The said liquid crystal display device WHEREIN: It is preferable that the angle which the orientation axis | shaft of an optical film (2) and the rubbing axis | shaft of the glass substrate of a liquid crystal cell make is -10 degrees-10 degrees. The liquid crystal display device in which the angle formed by the alignment axis of the optical film (2) and the rubbing axis of the glass substrate of the liquid crystal cell is controlled within the above range can realize a wider viewing angle, and the display screen is viewed from an oblique direction. This is preferable in that display coloring can be suppressed and an image with a small gradation inversion region can be displayed. The liquid crystal display device is preferably applied to a liquid crystal display mode that is an OCB mode.

  The laminated optical film of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 3, the laminated optical film of the present invention includes an optical film (1), an optical film (2) obtained by obliquely orienting an optically negative uniaxial material, and an optical film. (3) are stacked. FIG. 1 shows a laminated optical film in which an optical film (2) is disposed in the middle. FIG. 2 shows a laminated optical film in which an optical film (3) is disposed in the middle. FIG. 3 shows a laminated optical film in which the optical film (1) is disposed in the middle. Any order may be sufficient as the lamination | stacking order of an optical film, and another optical film may be laminated | stacked up and down further or between layers. Among these, the configuration of FIG. 1 or FIG. 2 is preferable. The configuration of FIG. 2 is particularly preferable.

  The angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (3) is preferably −10 ° to 10 ° or 80 ° to 100 °. The angle formed by the slow axis of the optical film (3) is approximately parallel (0 ° ± 10 °) or substantially orthogonal (90 ° ±) with the orientation axis of the optical film (2) as a reference (0 °). 10 °). When the angle is substantially parallel, it is preferably −5 ° to 5 °, more preferably −2 ° to 2 °. When the angle is substantially orthogonal, it is preferably 85 ° to 95 °, more preferably 88 ° to 92 °.

  The angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (1) is preferably 35 ° to 55 °. The angle is determined with the orientation axis of the optical film (2) as a reference (0 °). The angle is preferably 43 ° to 47 °, and more preferably 44 ° to 46 °.

  In addition, the direction of the orientation axis of the optical film (2) is defined as follows. 10 and 11 show model drawings when the optical film (2) is viewed from the cross-sectional direction. The disk d in the figure indicates a material that exhibits optically negative uniaxiality. In FIG. 10, the optical axes x of the respective disks d are directed in different directions. In FIG. 11, the optical axis x of each disk faces the same direction. The direction of the orientation axis y of the optical film (2) is obtained by projecting the optical axis x into the plane of the optical film (2). The direction of the orientation axis y can be measured using an automatic birefringence measuring apparatus KOBRA21ADH or the like.

  Moreover, a polarizer (P) can be laminated on the laminated optical film to obtain a polarizing plate with an optical compensation function. 4 to 9 show a polarizing plate (P1) with an optical compensation function in which a polarizer (P) is laminated on the laminated optical film shown in FIGS. In addition, although the lamination position of the polarizer (P) with respect to the laminated optical film is not particularly limited, the optical film (1) as shown in FIG. 4 or FIG. 5 from the viewpoint of widening the viewing angle when mounted on a liquid crystal display device. It is preferable to laminate a polarizer (P) on the side. Moreover, it is preferable to laminate | stack so that an optical film (2) may become an other side with respect to a polarizer (P) like FIG. 5 or FIG. The case of FIG. 5 is particularly preferable.

  The angle formed by the orientation axis of the optical film (2) and the absorption axis of the polarizer (P) is preferably 35 ° to 55 °. The angle is determined with the orientation axis of the optical film (2) as a reference (0 °). The angle is preferably 43 ° to 47 °, and more preferably 44 ° to 46 °.

  In addition, FIG. 1 thru | or FIG. 9 is an example in case each optical film and polarizer are laminated | stacked through the adhesive layer (a). The pressure-sensitive adhesive layer (a) may be a single layer, or two or more layers may be superposed. The pressure-sensitive adhesive layer may be omitted.

  The laminated optical film or the polarizing plate with optical compensation function (P1) is suitably used in an image display device. The laminated optical film or the polarizing plate with optical compensation function (P1) is suitably used for a liquid crystal display device. When used in a liquid crystal display device, the angle formed by the alignment axis of the optical film (2) and the rubbing axis of the glass substrate of the liquid crystal cell is preferably −10 ° to 10 °. The angle is determined with the orientation axis of the optical film (2) as a reference (0 °). The angle is preferably −5 ° to 5 °, and more preferably −2 ° to 2 °.

In the optical film (1), the direction in which the in-plane refractive index is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. When nx ₁ , ny ₁ , and nz ₁ are set,
_{Nz = (nx 1 -nz 1)} / (nx 1 -ny 1) Nz coefficient expressed by is, 0 ≦ Nz ≦ 1, can be used without particular limitation to satisfy.

  The production method of the optical film (1) is not particularly limited. For example, a method of stretching a polymer film biaxially in the plane direction, a method of stretching uniaxially or biaxially in the plane direction, and stretching in the thickness direction, etc. Can be given. In addition, there is a method in which a heat-shrinkable film is bonded to a polymer film and the polymer film is stretched or / and contracted under the action of the shrinkage force by heating. By controlling the refractive index in the thickness direction by these methods, the orientation state is controlled so that the three-dimensional refractive index of the stretched film becomes 0 ≦ Nz ≦ 1.

  Examples of the polymer forming the optical film (1) include polyolefins such as polycarbonate and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, norbornene polymers, polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, and polyhydroxyethyl acrylate. , Cellulose polymers such as hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyarylate, polysulfone, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyvinyl chloride, triacetyl cellulose, Acrylic polymer, styrene polymer or this Binary and ternary various copolymers, graft copolymers, and any blend thereof.

The optical film (1) has 0 ≦ Nz ≦ 1, but when the film thickness is d ₁ (nm), the front phase difference ((nx ₁ −ny ₁ ) × d ₁ ) is 10 It is preferably ˜500 nm, and more preferably 100 to 350 nm. The thickness direction retardation ((nx ₁ −nz ₁ ) × d ₁ ) is preferably 10 to 400 nm, and more preferably 50 to 300 nm.

The thickness (d ₁ ) of the optical film (1) is not particularly limited, but is preferably 1 to 150 μm, and more preferably 5 to 50 μm.

  The optically negative uniaxial material forming the optical film (2) is a material in which the refractive index of the principal axis in one direction is smaller than the refractive index in the other two directions in the three-dimensional refractive index ellipsoid. Show.

  Examples of the optically negative uniaxial material include polyimide materials and liquid crystal materials such as discotic liquid crystal compounds. In addition, a material in which these materials are the main components and mixed and reacted with other oligomers or polymers to fix a state in which a material exhibiting negative uniaxiality is tilt-oriented is fixed to form a film. When a discotic liquid crystal compound is used, the tilted alignment state of the liquid crystalline molecules is determined depending on the molecular structure, the type of alignment film, and additives that are appropriately added to the optically anisotropic layer (eg, plasticizer, binder, surfactant). ) Can be controlled by using.

The direction in which the refractive index in the film plane of the optical film (2) is the maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. ₂ , ny ₂ , nz ₂ , and the film thickness is d ₂ (nm), the front phase difference ((nx ₂ −ny ₂ ) × d ₂ ) is preferably 0 to 200 nm. 1 to 150 nm is more preferable. The thickness direction retardation: ((nx ₂ −nz ₂ ) × d ₂ ) is preferably 10 to 400 nm, and more preferably 50 to 300 nm.

The thickness of the optical film ₍₂₎ (d 2) is not particularly limited but is preferably 1 to 200 [mu] m, more preferably 2～150Myuemu.

In the optical film (3), the direction in which the in-plane refractive index is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis. nx _3, ny ₃ when and with nz _3, can be used without particular limitation for satisfying _{nx 3 ≧ ny 3> nz 3} . The optical film (3), the refractive index, nx _3> and ny _3> nz ₃ optical film (3) is _{-1, nx 3 = ny 3>} nz optical film (3) ₃ -2 Either can be used. In the optical film (3) -2, nx ₃ = ny ₃ indicates that there is substantially no phase difference. Among these, it is more preferable to use the optical film (3) -1.

  Optical film (3) -1 is, for example, 1a: a method of stretching or shrinking after coating a retardation film made of a polymer such as a polyimide material on a resin film, 1b: a method of biaxially stretching a plastic film, Etc. The optical film (3) -2 is, for example, 2a: a method of forming a cholesteric layer by curing a nematic liquid crystal monomer or the like, and 2b: applying a retardation film made of a polymer such as a polyimide material on a resin film. Obtained by methods, etc.

First, as a method for obtaining the optical film (3) -1, a method 1a: a method of stretching or shrinking after coating a retardation film made of a polymer such as a polyimide material on a resin film will be described. For example, the method 1a can be performed as follows. Examples of the polymer forming the retardation film include polyamide, polyester, poly (ether ketone), poly (amidoimide), poly (ester imide) and the like in addition to polyimide. These materials are preferably used at least one selected from these materials. Among these, those that are optically transparent are preferably used. Incidentally, as the material, as long as it can satisfy the characteristics of _{nx 3> ny 3> nz 3} , conventionally known polymer materials can be appropriately used to can be used alone or in any combination.

  For example, as the polyimide, a soluble polyimide composed of an aromatic dianhydride and a polyaromatic diamine as described in JP-A-8-511812 is preferably used. Examples of poly (ether ketone) include polyaryl ether ketone, and fluorine-containing aryl ether ketone polymers described in JP-A Nos. 2001-64226 and 2001-49110 are preferably used.

  The molecular weight of these polymers is not particularly limited, but the weight average molecular weight (Mw) is preferably in the range of 1,000 to 1,000,000, more preferably in the range of 2,000 to 500,000.

The manufacturing conditions and process of the retardation film are not particularly limited as long as the method can satisfy the characteristics (nx ₃ > ny ₃ > nz ₃ ) of the retardation film of the present invention. From the point that a film with a large thickness direction retardation (Rth) can be efficiently produced in a thin layer and with a simple process, a polymer is coated on a polymer substrate such as a resin film or a sheet, and as required. The stretching / stretching process is preferably performed.

  When the polymer is applied to a resin film or sheet or the like, a heat melting method may be used, or the polymer may be dissolved in a solvent and applied as a solution. From the viewpoint of production efficiency and optical anisotropy control, a method of applying a polymer solution is preferred. As the solvent, for example, the solvent for dissolving polyimide is not particularly limited as long as it can dissolve polyimide, and can be appropriately selected according to the kind of polymer. Examples of the solvent include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, xylene , Aromatic hydrocarbons such as methoxybenzene, 1,2-dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; acetic acid Ester solvents such as ethyl and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether Alcohol solvents such as diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile solvents such as acetonitrile and butyronitrile; Examples include ether solvents such as diethyl ether, dibutyl ether, and tetrahydrofuran; carbon disulfide, ethyl cellosolve, butyl cellosolve, and the like. These solvents can be used alone or in combination. From the viewpoint of viscosity, the polymer solution may be used by mixing 5 to 50 parts by weight, preferably 10 to 40 parts by weight of the polymer with respect to 100 parts by weight of the solvent.

  The polymer substrate is preferably optically transparent from the viewpoint of use as an integral product with a polymer material. There is no particular limitation as long as it is optically transparent.

  Examples of polymer base materials include acetate resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, and the like. Resin, polynorbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin, liquid crystal polymer, etc. Can do.

  The thickness of the polymer substrate can be appropriately determined according to the purpose of use, etc., but is preferably 5 to 500 μm, more preferably 10 to 200 μm, and still more preferably 15 to 150 μm from the viewpoint of strength and thinning. It is good to be.

  The coating treatment can be performed by an appropriate method such as a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, or a gravure printing method.

  After coating, the polymer is fixed on the resin film or sheet by natural drying (air drying) or heating at 40 ° C. to 200 ° C., and a polymer layer is formed on the resin film or sheet. The obtained optically anisotropic layer may be used in the form of a laminate as an integrated product of the resin film or sheet, or may be used after being peeled off from the resin film or sheet.

  In order to satisfy optical properties, the polymer layer may be subjected to the following stretching or shrinking treatment in the form of a laminate with the resin film or sheet, or the polymer layer may be peeled off from the resin film or sheet. The following expansion / contraction or contraction treatment may be performed. In forming the polymer layer, various additives such as stabilizers, plasticizers and metals can be blended as necessary.

  The stretching or shrinking treatment is not particularly limited as long as it can satisfy the characteristics of the optically anisotropic layer of the present invention. As the stretching method, there is generally a stretching method. Free end-axial stretching and fixed end-axial stretching are preferred, but sequential biaxial stretching and simultaneous biaxial stretching can also be used. Further, Δnd (front phase difference, thickness direction phase difference) can be expressed by shrinkage. It is also possible to use a resin film or sheet that is a coated base material that is contracted by using a dimensional change, or a base material that is positively provided with a contracting performance. In this case, it is desirable to control the shrinkage rate using a stretching machine or the like.

  Next, as a method for obtaining the optical film (3) -1, a method 1b: a method of biaxially stretching a plastic film will be described. According to the method 1b, the optical film (3) -1 is obtained, for example, as a stretched polymer film using a thermoplastic resin as a main raw material. In the present invention, the “stretched film” refers to a plastic film in which tension is applied to an unstretched film at an appropriate temperature, or tension is further applied to a previously stretched film to increase molecular orientation in a specific direction.

  The polymer film containing the thermoplastic resin as a main material is not particularly limited, and examples thereof include an extruded film, a cast film, a composite film, and a blend film. The polymer film includes plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, thickeners, and the like. Various additives may be included. In the present invention, a cast film is preferably used because it is easy to control the retardation value in the thickness direction.

  In the present invention, the “extruded film” refers to a continuous film produced by extrusion, and includes a T-die film, a tubular film, an inflation film, and the like. The “cast film” refers to a film obtained by casting a polymer solution on the surface of a metal plate or plastic substrate and evaporating the solvent. Further, “composite film” refers to a laminate of two or more layers, and “blend film” refers to a mixture of two or more types of resins.

  Examples of the thermoplastic resin used in the stretched film of the polymer film mainly composed of the thermoplastic resin include cellulose resins such as diacetyl cellulose and triacetyl cellulose, polycarbonate resins, norbornene resins, and ethylene / propylene copolymers. Examples thereof include, but are not limited to, polyolefin resins such as polymers, amide resins such as nylon and aromatic polyamide, and imide resins such as polyimide and polyimideamide. The above amorphous polymer can also be used after conventionally known polymer modification. Examples of the polymer modification include modification such as copolymerization, branching, crosslinking, molecular terminal, and stereoregularity. Among these, norbornene resins and polycarbonate resins are preferably used as the thermoplastic resin film used in the present invention.

  The stretching method for applying tension to the polymer film is not particularly limited, but there are a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, an oblique stretching method, and the like. Can be mentioned. Among these, in the method 1b, the vertical and horizontal simultaneous biaxial stretching method and the vertical and horizontal sequential biaxial stretching method are preferably used. As an apparatus for performing the stretching, an appropriate stretching machine such as a roll stretching machine, a tenter stretching machine, or a biaxial stretching machine can be used. Moreover, the said heat extending | stretching can also be divided and performed in 2 steps or 3 times or more processes. The direction in which the polymer film is stretched may be the film longitudinal direction (MD direction), the width direction (TD direction), or the stretching method described in FIG. 1 of JP-A-2003-262721. The direction may be oblique by a method such as

  Next, as a method for obtaining the optical film (3) -2, a method 2a: a method of forming a cholesteric layer by curing a nematic liquid crystal monomer or the like will be described. In the method 2a, for example, a nematic liquid crystal monomer is twisted using a chiral agent to give a cholesteric structure and then polymerized or crosslinked to be cured to obtain a cholesteric layer. As the nematic liquid crystal monomer, for example, those having a structure exemplified by chemical formula (1) described later are preferable. These nematic liquid crystal monomers preferably contain either a polymerizable monomer or a crosslinkable monomer. The cholesteric layer preferably further contains at least one of a polymerization agent and a crosslinking agent. For example, substances such as an ultraviolet curing agent, a photocuring agent, and a thermosetting agent can be used.

  The proportion of the liquid crystal monomer in the cholesteric layer is preferably in the range of 75 to 95% by weight, more preferably in the range of 80 to 90% by weight. The ratio of the chiral agent to the liquid crystal monomer is preferably in the range of 5 to 23% by weight, and more preferably in the range of 10 to 20% by weight. Further, the ratio of the crosslinking agent or the polymerization agent to the liquid crystal monomer is preferably in the range of 0.1 to 10% by weight, more preferably in the range of 0.5 to 8% by weight, and particularly preferably 1 to 1% by weight. It is in the range of 5% by weight.

  The thickness of the cholesteric layer is not particularly limited, but is preferably in the range of 0.1 to 10 μm from the viewpoints of orientation disorder and prevention of transmittance reduction, selective reflectivity, coloring prevention, productivity, and the like. Preferably it is the range of 0.5-8 micrometers, Most preferably, it is the range of 1-5 micrometers.

  The optical film (3) -2 obtained by the method 2a may be formed from, for example, only the cholesteric layer as described above, but further includes a substrate, and the laminate in which the cholesteric layer is laminated on the substrate. It may be.

  An example of the method 2a will be specifically described below. First, a coating liquid containing the liquid crystal monomer, the chiral agent, and at least one of the crosslinking agent and the polymerization agent is prepared.

  As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable, and specific examples include a monomer represented by the following formula (1). One kind of these liquid crystal monomers may be used, or two or more kinds may be used in combination.

In the formula (1), A ¹ and A ² each represent a polymerizable group, and may be the same or different. One of A ¹ and A ² may be hydrogen. X represents a single bond, —O—, —S—, —C═N—, —O—CO—, —CO—O—, —O—CO—O—, —CO—NR—, —NR—, respectively. CO—, —NR—, —O—CO—NR—, —NR—CO—O—, —CH ₂ —O— or —NR—CO—NR, wherein R is H or C1-C4 Represents alkyl, and M represents a mesogen group.

  In the formula (1), Xs may be the same or different, but are preferably the same.

Among the monomers represented by the formula (1), each A ² is preferably located in the ortho position with respect to A ¹ .

A ¹ and A ² are each independently represented by the following formula Z-X- (Sp) _n (2)
And A ¹ and A ² are preferably the same group.

  In the above formula (2), Z represents a crosslinkable group, X is the same as in the above formula (1), and Sp consists of a linear or branched alkyl group having 1 to 30 C atoms. Represents a spacer, and n represents 0 or 1. The carbon chain in Sp may be interrupted by, for example, oxygen in the ether functional group, sulfur in the thioether functional group, a non-adjacent imino group, or a C1-C4 alkylimino group.

  In the formula (2), Z is preferably any one of atomic groups represented by the following formula. In the following formula, examples of R include groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl.

  In the formula (2), Sp is preferably any one of the atomic groups represented by the following formula. In the following formula, m is preferably 1 to 3, and p is preferably 1 to 12.

  In the formula (1), M is preferably represented by the following formula (3). In the following (3), X is the same as X in the formula (1). Q represents, for example, a substituted or unsubstituted alkylene or aromatic hydrocarbon group, and may be, for example, a substituted or unsubstituted linear or branched C1-C12 alkylene.

  When Q is the aromatic hydrocarbon atomic group, for example, an atomic group represented by the following formula or a substituted analog thereof is preferable.

  The substituted analog of the aromatic hydrocarbon group represented by the above formula may have, for example, 1 to 4 substituents per aromatic ring, and may include one aromatic ring or one group. Each may have 1 or 2 substituents. The substituents may be the same or different. Examples of the substituent include C1-C4 alkyl, halogen such as nitro, F, Cl, Br, and I, phenyl, C1-C4 alkoxy, and the like.

  Specific examples of the liquid crystal monomer include monomers represented by the following formulas (4) to (19).

  The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on the type, but is preferably in the range of 40 to 120 ° C., more preferably in the range of 50 to 100 ° C., and particularly preferably 60. It is the range of -90 degreeC.

  The chiral agent is not particularly limited, as described above, for example, as long as the liquid crystal monomer is twisted to be aligned so as to have a cholesteric structure, but is preferably a polymerizable chiral agent. The above can be used. One kind of these chiral agents may be used, or two or more kinds thereof may be used in combination.

Specifically, as the polymerizable chiral agent, for example, chiral compounds represented by the following general formulas (20) to (23) can be used.
_{^{(Z-X 5) n Ch}} (20)
^{(Z-X 2 -Sp-X} 5) n Ch (21)
(P ¹ −X ⁵ ) _n Ch (22)
^{(Z-X 2 -Sp-X} 3 -M-X 4) n Ch (23)
In each of the above formulas, Z is the same as in the above formula (2), Sp is the same as in the above formula (2), and X ² , X ³ and X ⁴ are each independently a chemical single bond , -O-, -S-, -O-CO-, -CO-O-, -O-CO-O-, -CO-NR-, -NR-CO-, -O-CO-NR-,- NR-CO-O- and -NR-CO-NR- are represented, and the R represents H and C1-C4 alkyl. X ⁵ represents a chemical single bond, —O—, —S—, —O—CO—, —CO—O—, —O—CO—O—, —CO—NR—, —NR—CO—. , —O—CO—NR—, —NR—CO—O—, —NR—CO—NR, —CH ₂ O—, —O—CH ₂ —, —CH═N—, —N═CH— or — N≡N— is represented. R represents H and C1-C4 alkyl as described above. M represents a mesogen group as described above, and P ¹ represents hydrogen, a C1 to C30 alkyl group substituted with 1 to 3 C1 to C6 alkyl, a C1 to 30 acyl group, or a C3 to C8 cycloalkyl group. N is an integer of 1-6. Ch represents an n-valent chiral group. In the formula (23), at least one of X ³ and X ⁴ is —O—CO—O—, —O—CO—NR—, —NR—CO—O—, or —NR—CO—NR—. It is preferable that In the formula (22), when P ¹ is an alkyl group, an acyl group or a cycloalkyl group, for example, the carbon chain is oxygen in the ether functional group, sulfur in the thioether functional group, non-adjacent imino group or It may be interrupted by a C1-C4 alkylimino group.

  Examples of the chiral group of Ch include an atomic group represented by the following formula.

  In the atomic group, L is C1-C4 alkyl, C1-C4 alkoxy, halogen, COOR, OCOR, CONHR, or NHCOR, and R represents C1-C4 alkyl. In addition, the terminal in the atomic group represented by the above formula represents a bond with an adjacent group.

  Among the atomic groups, an atomic group represented by the following formula is particularly preferable.

In addition, the chiral compound represented by the above (21) or (23) is preferably an atomic group in which, for example, n is 2, Z represents H ₂ C═CH—, and Ch is represented by the following formula. .

  Specific examples of the chiral compound include compounds represented by the following formulas (24) to (44).

  In addition to the above-mentioned chiral compounds, for example, chiral compounds listed in RE-A 4342280 and German Patent Applications 19520660.6 and 195207041 can be preferably used.

  Although it does not restrict | limit especially as said polymerizer and a crosslinking agent, For example, the following can be used. Examples of the polymerization agent include benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN). Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, and metal chelate crosslinking. An agent can be used. These may be either one of them, or two or more of them may be used in combination.

The coating liquid can be prepared, for example, by dissolving and dispersing the liquid crystal monomer and the like in an appropriate solvent. Examples of the solvent include, but are not limited to, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene, phenol, p- Phenols such as chlorophenol, o-chlorophenol, m-cresol, o-cresol, p-cresol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, acetone, methyl ethyl ketone (MEK), ketone solvents such as methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone and N-methyl-2-pyrrolidone, and esters such as ethyl acetate and butyl acetate Solvent, alcohol solvent 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 Amide solvents such as dimethylacetamide, 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, etc. Can be used. Among these, toluene, xylene, mesitylene, MEK, methyl isobutyl ketone, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, and ethyl acetate cellosolve are preferable.
These solvents may be, for example, one kind or a mixture of two or more kinds.

  The addition ratio of the chiral agent is appropriately determined according to, for example, a desired helical pitch and a desired selective reflection wavelength band, and the addition ratio with respect to the liquid crystal monomer is preferably in the range of 5 to 23% by weight. Is in the range of 10-20% by weight. By controlling the addition ratio of the liquid crystal monomer and the chiral agent in this manner, the selected wavelength band of the formed optical film can be made suitable.

  Further, the combination of the liquid crystal monomer and the chiral agent is not particularly limited. Specifically, the combination of the monomer agent of the formula (10) and the chiral agent of the formula (38), the formula ( And a combination of the monomer agent of 11) and the chiral agent of the above formula (39).

  The addition ratio of the crosslinking agent or the polymerization agent to the liquid crystal monomer is, for example, in the range of 0.1 to 10% by weight, preferably in the range of 0.5 to 8% by weight, more preferably 1 to 5% by weight. Range. If the ratio of the crosslinking agent or the polymerization agent to the liquid crystal monomer is 0.1% by weight or more, for example, curing of the cholesteric layer is sufficiently easy, and if it is 10% by weight or less, for example, the liquid crystal monomer is Since the temperature range in which the cholesteric alignment is performed, that is, the temperature at which the liquid crystal monomer becomes a liquid crystal phase is in a sufficient range, temperature control in the alignment step described later is further facilitated.

  Moreover, you may mix | blend various additives with the said coating liquid suitably as needed, for example. Examples of the additive include an anti-aging agent, a modifier, a surfactant, a dye, a pigment, a discoloration inhibitor, and an ultraviolet absorber. Any one of these additives may be added, or two or more of them may be used in combination. Specifically, as the anti-aging agent, for example, phenol compounds, amine compounds, organic sulfur compounds, phosphine compounds, etc., and as the modifier, for example, glycols, silicones, alcohols, etc. A well-known thing can be used, respectively. The surfactant is added, for example, to smooth the surface of the optical film. For example, a surfactant such as silicone, acrylic or fluorine can be used, and silicone is particularly preferable.

  Thus, when a liquid crystal monomer is used, the prepared coating liquid shows the viscosity excellent in workability | operativity, such as coating and expansion | deployment, for example. The viscosity of the coating liquid usually varies depending on the concentration and temperature of the liquid crystal monomer, but when the monomer concentration in the coating liquid is in the range of 5 to 70% by weight, the viscosity is, for example, 0. The range is 2 to 20 mPa · s, preferably 0.5 to 15 mPa · s, and particularly preferably 1 to 10 mPa · s. Specifically, when the monomer concentration in the coating solution is 30% by weight, for example, the range is 2 to 5 mPa · s, and preferably 3 to 4 mPa · s. If the viscosity of the coating liquid is 0.2 mPa · s or more, for example, generation of a liquid flow by running the coating liquid can be further prevented, and if the viscosity is 20 mPa · s or less, for example, the surface Smoothness is further improved, thickness unevenness can be further prevented, and coating properties are also excellent. In addition, as said viscosity, although the range in the temperature of 20-30 degreeC was shown, it is not limited to this temperature.

  Next, the coating liquid is applied onto the alignment substrate to form a spread layer.

  The coating liquid may be flow-deployed by a conventionally known method such as a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, a curtain coating method, a spray coating method, Of these, spin coating and extrusion coating are preferred from the viewpoint of coating efficiency.

The alignment substrate is not particularly limited as long as the liquid crystal monomer can be aligned. For example, a substrate obtained by rubbing the surface of various plastic films or plastic sheets with a rayon cloth or the like can be used. The plastic is not particularly limited. For example, polyolefin such as triacetyl cellulose (TAC), polyethylene, polypropylene, poly (4-methylpentene-1), polyimide, polyimide amide, polyether imide, polyamide, polyether ether. Ketone, polyether ketone, polyketone sulfide, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulosic plastic And epoxy resins and phenol resins. Also, the plastic film or sheet as described above is placed on the surface of a metal substrate such as aluminum, copper, iron, etc., a ceramic substrate, a glass substrate, etc., or a SiO ₂ oblique vapor deposition film is formed on the surface. It is also possible to use such things. Moreover, the laminated body which laminated | stacked the above-mentioned plastic film and sheet | seat on the oriented film etc. which gave the birefringent property etc. which performed the extending | stretching processes, such as uniaxial stretching, can also be used as an oriented substrate. Further, when the substrate itself has birefringence, it is preferable because the rubbing treatment as described above or the lamination of a birefringent film on the surface is unnecessary. As a method for imparting birefringence to the substrate itself as described above, for example, in the formation of the substrate, there is a method of performing casting, extrusion molding, or the like in addition to the stretching treatment.

  Subsequently, the liquid crystal monomer is aligned in a liquid crystal state by subjecting the spread layer to a heat treatment. Since the spread layer contains a chiral agent together with the liquid crystal monomer, the liquid crystal monomer in a liquid crystal phase (liquid crystal state) is aligned in a state where a twist is imparted by the chiral agent. That is, the liquid crystal monomer exhibits a cholesteric structure (helical structure).

  The temperature condition of the heat treatment can be appropriately determined according to, for example, the type of the liquid crystal monomer, specifically the temperature at which the liquid crystal monomer exhibits liquid crystallinity, but is usually in the range of 40 to 120 ° C., preferably It is the range of 50-100 degreeC, More preferably, it is the range of 60-90 degreeC. If the temperature is 40 ° C. or higher, the liquid crystal monomer can usually be sufficiently aligned, and if the temperature is 120 ° C. or lower, for example, selection of various alignment substrates as described above in terms of heat resistance. The nature is also wide.

  Next, the liquid crystal monomer and the chiral agent are polymerized or crosslinked by performing a crosslinking treatment or a polymerization treatment on the spread layer in which the liquid crystal monomer is aligned. As a result, the liquid crystal monomer is polymerized / crosslinked with each other while being aligned with a cholesteric structure, or polymerized / crosslinked with a chiral agent, and the alignment state is fixed. The formed polymer becomes a non-liquid crystal polymer by fixing the alignment state.

  The polymerization treatment and the crosslinking treatment can be appropriately determined depending on, for example, the kind of the polymerization agent and the crosslinking agent to be used. For example, when a photopolymerization agent or a photocrosslinking agent is used, light irradiation is performed, and when an ultraviolet polymerization agent or an ultraviolet crosslinking agent is used, ultraviolet irradiation is performed.

  By such a method 2a, an optical film (3) -2 formed from a non-liquid crystalline polymer having a cholesteric structure aligned on the alignment substrate is obtained.

  The optical film (3) -2 obtained by the method 2a may be peeled off from the alignment substrate and used as it is as a retardation film for compensation as described above, or the alignment substrate It can also be used as a phase difference plate in a state of being laminated. Another optical film (1) or optical film (2) may be used as a substrate, and in that case, the total thickness can be reduced.

Next, as a method for obtaining the optical film (3) -2, a method 2b: a method of coating a retardation film made of a polymer such as a polyimide material on a resin film will be described. In the method 2b, for example, there is a method in which the step of stretching or shrinking is not performed in the method 1a, which is a method for obtaining the optical film (3) -1. Thus, if Kere, the optical film (3) that satisfies _{nx 3 = ny 3> nz 3} -2 are obtained.

The optical film (3) -1 preferably has a front phase difference ((nx ₃ −ny ₃ ) × d ₃ ) of 10 to 500 nm, where d ₃ (nm) is the thickness of the film. More preferably, it is ˜350 nm. The thickness direction retardation ((nx ₃ −nz ₃ ) × d ₃ ) is preferably 0 to 500 nm, and more preferably 1 to 350 nm. The thickness (d ₃ ) of the optical film (3) -1 is not particularly limited, but is preferably 1 to 200 μm, and more preferably 2 to 80 μm.

In the optical film (3) -2, when the film thickness is d ₃ (nm), the front phase difference ((nx ₃ −ny ₃ ) × d ₃ ) is preferably 0 to 10 nm. More preferably, it is ˜5 nm. The thickness direction retardation ((nx ₃ −nz ₃ ) × d ₃ ) is preferably 0 to 600 nm, and more preferably 1 to 450 nm. The thickness (d ₃ ) of the optical film (3) -2 is not particularly limited, but is preferably 1 to 200 μm, and more preferably 2 to 30 μm.

  The polarizer (P) usually has a protective film on one side or both sides. The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymers such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. And polyene-based oriented films such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring 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.

  The protective film provided on one side or both sides of the polarizer preferably has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the material of the protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymers, and the like. Examples thereof include styrene polymers such as (AS resin) and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of polymers that form protective films include polymer blends. Other examples include films made of thermosetting or ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.

  A protective film that can be particularly preferably used in terms of polarization characteristics and durability is a triacetylcellulose film whose surface is saponified with an alkali or the like. Although the thickness of a protective film can be determined suitably, generally it is about 10-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 20-300 micrometers is especially preferable, and 30-200 micrometers is more preferable.

  Moreover, it is preferable that a protective film has as little color as possible. Therefore, Rth = (nx−nz) · d (where nx is the refractive index in the slow axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. In addition, when providing a protective film in the both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used. The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of aqueous adhesives include polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, and the like.

  As the protective film, a hard coat layer, an antireflection treatment, an anti-sticking treatment, or a treatment subjected to diffusion or anti-glare treatment can be used.

  Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the protective film itself, or can be provided separately from the transparent protective layer as an optical layer.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer (a) is not particularly limited, but for example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer Can be appropriately selected and used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  The pressure-sensitive adhesive layer can be formed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method of attaching it directly on the substrate or liquid crystal film by an appropriate development method such as a casting method or a coating method, or forming an adhesive layer on a separator according to the above and transferring it onto the liquid crystal layer The method to do.

  The pressure-sensitive adhesive layer includes, for example, natural and synthetic resins, in particular, tackifier resins, fillers and pigments made of glass fibers, glass beads, metal powders, other inorganic powders, coloring agents, oxidation agents, and the like. You may contain the additive added to adhesion layers, such as an inhibitor. Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

  Moreover, although the adhesive layer (a) is drawn in FIGS. 1 to 9, these are not necessarily required. For example, a compensation layer (optical film) formed by coating can be directly formed on another compensation layer (optical film) to bond both layers without an adhesive layer. FIGS. 4 to 9 show the case where the pressure-sensitive adhesive layer (a) is not shown between the polarizer (P) and the laminated optical film. a) can be provided.

  A separator is temporarily attached to the exposed surface of the pressure-sensitive adhesive layer for the purpose of preventing contamination until it is put into practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In addition, each layer such as the optical film and the pressure-sensitive adhesive layer is treated with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. It is possible to give UV absorption ability by this method.

  The polarizing plate with an optical compensation function of the present invention is suitably used in an image display device. For example, it can be preferably used for forming various devices such as a liquid crystal display device. Among them, it is suitably used as a polarizing plate with an optical compensation function for OCB mode.

  FIG. 12 shows the polarizing plate with optical compensation function (P1) of the present invention shown in FIGS. 4 to 9 arranged in the liquid crystal display device on the backlight (BL) side of the liquid crystal cell (L) through an adhesive layer. It is a thing. The side of the polarizing plate with optical compensation function (P1) laminated on the lower side (backlight side) liquid crystal cell (L) is not particularly limited, but the polarizer (P) of the polarizing plate with optical compensation function (P1) is a liquid crystal. It is preferable to be farthest from the cell (L) side. Liquid crystal is sealed in the liquid crystal cell (L). On the upper part of the liquid crystal cell substrate, the upper polarizing plate with optical compensation function (P2) and various optical films are provided. The polarizing plate with optical compensation function (P2) is also preferably such that the polarizer (P) is farthest from the liquid crystal cell (L) side. The polarizing plate with optical compensation function (P2) is obtained by laminating various optical films on the polarizer (P). Moreover, as shown in FIG. 14, the polarizing plate (P1) with an optical compensation function of the present invention can be used on both sides of the liquid crystal cell. The embodiment shown in FIG. 14 is preferable. In the drawing, the pressure-sensitive adhesive layer is not shown in the laminate of the liquid crystal cell (L) and the polarizing plate with optical compensation function (P1) and (P2).

  FIG. 13 shows the polarizing plate with optical compensation function (P1) of the present invention shown in FIGS. 4 to 9, which is arranged on the upper side of the liquid crystal cell (L) via an adhesive layer in the liquid crystal display device. The side of the polarizing plate with optical compensation function (P1) laminated on the upper liquid crystal cell (L) is not particularly limited, but the polarizer (P) of the polarizing plate with optical compensation function (P1) is from the liquid crystal cell (L) side. It is preferable to be the farthest away. Liquid crystal is sealed in the liquid crystal cell (L). A polarizing plate (P2) with an optical compensation function is provided below the liquid crystal cell substrate. The polarizing plate with optical compensation function (P2) is also preferably such that the polarizer (P) is farthest from the liquid crystal cell (L) side.

  When the laminated optical film of the present invention and the polarizing plate with optical compensation function (P1) are mounted on a liquid crystal display device or the like, the optical film (2) is an average of optically negative uniaxial materials. It is arranged so that the optical axis (average angle of tilt alignment) is oriented in the same direction as the alignment direction of the liquid crystal molecules at the center (midplane) of the thickness direction of the liquid crystal cell to be aligned by applying voltage up and down. preferable. In this case, the alignment of the liquid crystal cell may be twisted or non-twisted, but is preferably non-twisted.

  The liquid crystal display devices shown in FIGS. 12, 13, and 14 show an example of a liquid crystal cell. The laminated optical film of the present invention and the polarizing plate with optical compensation function (P1) are used in various other liquid crystal display devices. Applicable.

  In addition, the polarizing plate which bonded the polarizing plate and the brightness enhancement film is normally provided and used on the back side of the liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that emits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is, but from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. A phase difference layer, for example, a phase difference layer that functions as a half-wave plate, can be used to superimpose. Accordingly, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers having different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by assembling components such as a liquid crystal cell, an optical element, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that the polarizing plate with optical compensation function (P1) of the present invention is used, and it can be based on the conventional one. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used. Of these, the OCB type is particularly preferably used.

  On the back side of the liquid crystal cell, an appropriate liquid crystal display device such as a lighting system using a backlight or a reflector can be formed. In that case, the polarizing plate with a compensation function of the present invention can be installed on one side or both sides of the liquid crystal cell. When optical elements are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In each example, parts are parts by weight.

  The refractive index and retardation of each optical film are measured using the automatic birefringence measuring device (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA21ADH) using the main refractive indices nx, ny and nz in the film plane and in the thickness direction. ), The characteristics at λ = 590 nm were measured.

  In the optical film (2), the inclination angle formed from the average optical axis of the optical material that is tilt-oriented and the normal direction of the optical film (2) is to the left and right with the optical film (2) as the slow axis. The phase difference was measured with the measuring device at an angle of 50 ° to 50 °, and the absolute value of the angle indicating the minimum phase difference was obtained. In the measurement, the measurement angle when the incident direction of light from the light source of the measuring instrument coincided with the normal to the film plane was set to 0 °.

(Polarizer)
A polarizing plate (SEG1224DU) made by Nitto Denko was used.

(Optical film (1))
A heat-shrinkable film made of a biaxially stretched polyester film was attached to both sides of a transparent polycarbonate film having a thickness of 70 μm via an adhesive layer. Then, it hold | maintained with the simultaneous biaxial stretching machine, and extended | stretched 1.08 time at 150 degreeC, and obtained the optical film (1). The obtained optical film (1) had a thickness: 68 μm, a front phase difference: 275 nm, a thickness direction retardation: 206 nm, and an Nz coefficient: 0.75.

(Optical film (2))
WVSA128 (thickness 83 μm) manufactured by Fuji Photo Film Co., Ltd. was used. The film is prepared by applying a discotic liquid crystal to a support, and has a front phase difference of 33 nm, a thickness direction retardation of 160 nm, and an inclination angle of an average optical axis that is inclined and aligned: 40 °.

(Optical film (3))
2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was used as the tetracarboxylic dianhydride, and 2,2-bis (trifluoromethyl) -4,4′- as the diamine. Using diaminobiphenyl, polyimide was obtained according to a conventional method. The polyimide had a polymerization average molecular weight (Mw) of 124,000 and an imidation ratio of 99.9%. 17.7 parts by weight of the polyimide was dissolved in 100 parts by weight of methyl isobutyl ketone to prepare a 15% by weight polyimide solution. This polyimide solution was applied to the surface of the triacetyl cellulose film in one direction and dried at 135 ° C. for 5 minutes. Optical film (3) -2 was obtained by adjusting the coating amount. When the thickness was 5.5 μm, the in-plane retardation was 0 nm and the thickness direction retardation was 217 nm. This was designated as optical film (3) -2-1. When the thickness was 10.5 μm, the in-plane retardation was 0 nm and the thickness direction retardation was 420 nm. This was designated as optical film (3) -2-2. These satisfied nx ₃ = ny ₃ > nz ₃ .

(Production of liquid crystal cell)
Δn (difference between ordinary light refractive index and extraordinary light refractive index) = 0.1317 nematic liquid crystal, easy axis 0 ° of front substrate, easy axis 0 ° of rear substrate, cell gap 6.46 μm, An OCB mode liquid crystal cell with a pretilt angle of 9.5 ° was obtained.

Example 1
(Laminated optical film and polarizing plate with optical compensation function)
The optical film (1), the optical film (2) and the optical film (3) are laminated via an adhesive layer (acrylic adhesive, thickness 30 μm) to obtain an optical film (2) / optical film (3). / The optical film (1) was laminated in this order to obtain a laminated optical film as shown in FIG. As the optical film (3), an optical film (3) -2-1 was used. Next, the polarizer (P) is laminated on the optical film (1) side of the laminated optical film via an adhesive layer (acrylic adhesive, thickness 30 μm), and an optical compensation function as shown in FIG. A polarizing plate (P1) was obtained.

  In the polarizing plate with an optical compensation function, the angle between the orientation axis of the optical film (2) and the slow axis of the optical film (3) is 0 °, the orientation axis of the optical film (2) and the optical film (1) The angle formed by the slow axis was 45 °, and the angle formed by the orientation axis of the optical film (2) and the absorption axis of the polarizer (P) was 45 °.

Example 2
In Example 1, the angle between the orientation axis of the optical film (2) and the slow axis of the optical film (3) is 0 °, and the slow axis of the orientation axis of the optical film (2) and the optical film (1). The optical compensation was performed in the same manner as in Example 1 except that the angle between the alignment axis of the optical film (2) and the absorption axis of the polarizer (P) was 45 °. A polarizing plate with function was obtained.

Example 3
(Laminated optical film and polarizing plate with optical compensation function)
A laminated optical film in the same manner as in Example 1 except that instead of the optical film (3) -2-1, the optical film (3) -2-2 was used as the optical film (3) in Example 1. Got. Moreover, it carried out similarly to Example 1 using the said laminated | multilayer optical film, and obtained the polarizing plate (P1) with an optical compensation function.

Comparative Example 1
(Laminated optical film and polarizing plate with optical compensation function)
The optical film (1) and the optical film (2) are laminated through an adhesive layer (acrylic adhesive, thickness 30 μm), and laminated in the order of optical film (2) / optical film (1). An optical film was obtained. Next, the polarizer (P) is laminated on the optical film (1) side of the laminated optical film via an adhesive layer (acrylic adhesive, thickness 30 μm), and an optical compensation function as shown in FIG. 15 is provided. A polarizing plate (P2) was obtained.

  In the polarizing plate with an optical compensation function, the angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (1) is 45 °, the orientation axis of the optical film (2) and the absorption axis of the polarizer. The angle formed by was set to 45 °.

Example 4
(Liquid crystal display device)
The polarizing plate with optical compensation function (P1) produced in Example 1 is on the viewing side of the liquid crystal cell, the polarizing plate with optical compensation function (P1) produced in Example 2 is on the backlight side of the liquid crystal cell, and FIG. Implemented as shown. The polarizing plates with optical compensation function (P1) on both sides were orthogonal to the absorption axis of each polarizer (P). All of the polarizing plates with optical compensation function (P1) were arranged such that the polarizer (P) was on the outside of the liquid crystal cell. In each of the polarizing plates with optical compensation function (P1), the angle between the alignment axis of the optical film (2) and the rubbing axis of the glass substrate of the liquid crystal cell was 0 °.

Example 5
(Liquid crystal display device)
The polarizing plate with optical compensation function (P1) produced in Example 1 is mounted on the viewing side of the liquid crystal cell, and the polarizer (P2) produced in Comparative Example 1 is mounted on the backlight side of the liquid crystal cell as shown in FIG. did. The polarizing plates (P1) and (P2) with optical compensation function on both sides were made to have orthogonal absorption axes of the respective polarizers (P). The polarizing plates with optical compensation function (P1) and (P2) were both arranged so that the polarizer (P) was on the outside of the liquid crystal cell. In each of the polarizing plates with optical compensation function (P1) and (P2), the angle formed by the alignment axis of the optical film (2) and the rubbing axis of the glass substrate of the liquid crystal cell was 0 °.

Comparative Example 2
(Liquid crystal display device)
The polarizing plate with optical compensation function (P2) produced in Comparative Example 1 was mounted on both sides of the liquid crystal cell as shown in FIG. In the polarizing plates with optical compensation function (P2) on both sides, the absorption axes of the respective polarizers (P) were orthogonal to each other. All of the polarizing plates with optical compensation function (P2) were arranged so that the polarizer (P) was on the outside of the liquid crystal cell. In each of the polarizing plates with optical compensation function (P2), the angle formed by the alignment axis of the optical film (2) and the rubbing axis of the glass substrate of the liquid crystal cell was 0 °.

  The viewing angle characteristics of the liquid crystal display device were evaluated. The results are shown in Table 1.

<Viewing angle>
A white image and a black image are displayed on the liquid crystal display device, and the EZ-contrast manufactured by ELDIM, up, down, left and right (azimuth angles are 0 °, 180 °, 90 °, 270 ° in order) In the XYZ display system, Y value, x value, and y value were measured. The angle at which the contrast (Y value (white image) / Y value (black image)) at that time was 10 or more was defined as the viewing angle.

It can be seen that while the viewing angle expansion performance is low in the vertical and horizontal directions of Comparative Example 2, the viewing angles are expanded in Examples 4 and 5. Accordingly, it goes without saying that a liquid crystal display device having a wide viewing angle and excellent visibility can be obtained by using the polarizing plate with an optical compensation function and the liquid crystal display device of the present invention. In particular, the viewing angle expansion effect in the OCB mode is tremendous.

It is one mode of a sectional view of a lamination optical film of the present invention. It is one mode of a sectional view of a lamination optical film of the present invention. It is one mode of a sectional view of a lamination optical film of the present invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of this invention. It is a conceptual diagram which shows the orientation axis | shaft of an optical film (2). It is a conceptual diagram which shows the orientation axis | shaft of an optical film (2). It is an example of sectional drawing of the liquid crystal display device example of this invention. It is an example of sectional drawing of the liquid crystal display device example of this invention. It is an example of sectional drawing of the liquid crystal display device example of this invention. It is one aspect | mode of sectional drawing of the polarizing plate with an optical compensation function of a comparative example. It is an example of sectional drawing of the liquid crystal display device example of a comparative example.

Explanation of symbols

1: Optical film (1)
2: Optical film (2)
3: Optical film (3)
P: Polarizing plate P1: Polarizing plate with optical compensation function L: Liquid crystal cell BL: Backlight

Claims (11)

The direction in which the refractive index in the film plane is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis, and the refractive indexes in the respective axial directions are nx ₁ , ny ₁ , nz _{If 1}
Nz = with _{(nx 1 -nz 1) / (} nx 1 -ny 1) Nz coefficient expressed by the, 0 ≦ Nz ≦ 1, the optical film (1) which satisfies the,
An optical film (2) that is formed of a material exhibiting optically negative uniaxiality and includes a portion where the material is inclined and oriented;
The direction in which the refractive index in the film plane is maximum is the X axis, the direction perpendicular to the X axis is the Y axis, and the thickness direction of the film is the Z axis, and the refractive indexes in the respective axial directions are nx ₃ , ny ₃ , nz If _{the 3} and the, the optical film (3) that satisfies nx ₃ ≧ ny _3> nz _3, but laminated optical film characterized by being laminated.   The laminated optical film according to claim 1, wherein the optically negative uniaxial material forming the optical film (2) is a discotic liquid crystal compound.   The optically negative uniaxial material forming the optical film (2) has an inclination angle between the average optical axis and the normal direction of the optical film (2) in the range of 5 ° to 50 °. The laminated optical film according to claim 1, comprising an oriented part.   The angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (3) is -10 ° to 10 ° or 80 ° to 100 °. The laminated optical film described.   The laminated optical film according to any one of claims 1 to 4, wherein an angle formed by the orientation axis of the optical film (2) and the slow axis of the optical film (1) is 35 ° to 55 °.   A polarizing plate with an optical compensation function, wherein the laminated optical film according to claim 1 and a polarizer are laminated.   The polarizing plate with an optical compensation function according to claim 6, wherein the angle between the orientation axis of the optical film (2) and the absorption axis of the polarizer is 35 ° to 55 °.   An image display device, wherein the laminated optical film according to claim 1 or the polarizing plate with an optical compensation function according to claim 6 or 7 is laminated.   A laminated optical film according to claim 1 or a polarizing plate with an optical compensation function according to claim 6 or 7 is laminated.   The liquid crystal display device according to claim 9, wherein an angle formed by the alignment axis of the optical film (2) in the laminated optical film and the rubbing axis of the glass substrate of the liquid crystal cell is −10 ° to 10 °. The liquid crystal display device according to claim 9 or 10, wherein the liquid crystal display mode is an OCB mode.