JP2009265174A - Method of manufacturing optical film, optical film, polarizing plate, liquid crystal panel and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing optical film capable of improving unevenness of polarization degree on both ends, in particular, of the width direction of film stock in the manufacturing of an optical film, and capable of obtaining a superior contrast characteristic when the optical film is used for a liquid crystal panel. <P>SOLUTION: The method of manufacturing the optical film, which includes a transparent film and a birefringent layer having a refractive index distribution of nx=ny>nz, includes a uniformizing step of an orientation axis for drawing the transparent film in the width direction with a draw ratio in the range of 1.05 to 1.25 times and a step of forming the birefringent layer on the drawn transparent film. Therein, nx, ny and nz respectively present refractive indexes of X-axis, Y-axis and Z-axis, wherein the X-axis is the axial direction along which the refractive index becomes maximum in the plane of the birefringent layer, the Y-axis is the axial direction vertical to the Y-axis, and the Z-axis presents the thickness direction vertical to the X-direction and the Y-direction. According to the manufacturing method, the unevenness of polarization on both ends of the width direction of film stock is improved as shown in Fig.6. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical film manufacturing method, an optical film, a polarizing plate, a liquid crystal panel, and a liquid crystal display device.

  Conventionally, in various liquid crystal display devices, a retardation plate is used for the purpose of optical compensation. Examples of such a retardation plate include various polymer film stretching methods such as an inter-roll tensile stretching method, an inter-roll compression stretching method, and a tenter transverse uniaxial stretching method (for example, see Patent Document 1), and biaxial stretching. An optical biaxial retardation plate produced by a method of imparting anisotropy by the method (for example, see Patent Document 2). In addition to this, a retardation plate using both a uniaxially stretched polymer film having positive optical anisotropy and a biaxially stretched polymer film having negative optical anisotropy having a small in-plane retardation value, (For example, refer to Patent Document 3.) Instead of the stretching method as described above, for example, a retardation plate in which a soluble polyimide film is formed on a substrate due to the properties of polyimide (for example, refer to Patent Document 4). .

  Non-liquid crystalline polymers such as polyimide exhibit optical characteristics of nx = ny> nz regardless of the orientation of the substrate. Further, by stretching the laminate of the substrate and the film in one direction in the plane, the film produces a refractive difference in the plane and exhibits optical characteristics having a refractive index distribution of nx> ny> nz ( For example, see Patent Document 5.) Here, nx, ny, and nz respectively indicate the refractive indexes of the X-axis, Y-axis, and Z-axis in the film, and the X-axis is an axial direction that indicates the maximum refractive index in the film plane. The Y axis is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis. For example, if the birefringent optical film having such optical characteristics is disposed between a liquid crystal cell and a polarizer of a liquid crystal display device, the display characteristics of the liquid crystal display device can be widened, It is useful as a viewing angle compensation film for liquid crystal cells. As a substrate constituting the optical film, a transparent resin film made of a cellulose-based material typified by triacetyl cellulose (TAC) is known (for example, see Patent Document 5).

JP-A-3-33719 Japanese Patent Laid-Open No. 3-24502 JP-A-4-194820 Japanese National Patent Publication No. 8-511812 JP 2004-46065 A

  Since such transparent resin films such as TAC have variations in the alignment axis, when the optical film is produced by providing a polyimide film or the like on this, the alignment axis of the optical film also varies. For this reason, there is a problem that the degree of polarization of the optical film also varies. When such an optical film is used as a viewing angle compensation film for a liquid crystal panel, there arises a problem that the contrast characteristics deteriorate. In particular, since the variation of the orientation axis at both ends of the optical film in the original fabric width direction is remarkable, it is not preferable to use both ends of the optical film in the original fabric width direction as a product.

  Accordingly, the present invention provides an optical film manufacturing method that improves the variation in the degree of polarization at both ends in the width direction of the original fabric and that provides excellent contrast characteristics when used in a liquid crystal panel. With the goal.

In order to achieve the above object, an optical film manufacturing method of the present invention includes a transparent film and a birefringent layer, and the birefringent layer has a refractive index distribution of nx = ny> nz. The step of homogenizing the orientation axis for stretching the transparent film in the width direction at a stretching ratio in the range of 1.05 to 1.25 times and the step of forming a birefringent layer on the stretched transparent film It is characterized by including.
(Nx, ny, and nz represent the refractive indexes of the X-axis, Y-axis, and Z-axis in the birefringent layer, respectively, and the X-axis represents the maximum refractive index in the plane of the birefringent layer. The Y axis is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.)

  The optical film of the present invention is manufactured by the method for manufacturing an optical film of the present invention.

  The polarizing plate of the present invention is a polarizing plate including an optical film and a polarizer, and the optical film is the optical film of the present invention.

  The first liquid crystal panel of the present invention is a liquid crystal panel including a liquid crystal cell and an optical member, wherein the optical member is the optical film of the present invention or the polarizing plate of the present invention, and the optical member is It is arranged on at least one side of the liquid crystal cell.

The second liquid crystal panel of the present invention includes a first polarizing plate, a second polarizing plate, and a liquid crystal cell, and the first polarizing plate is disposed on a backlight side of the liquid crystal cell, The polarizing plate is a liquid crystal panel disposed on the viewing side of the liquid crystal cell,
The first polarizing plate includes a first polarizer and a first birefringent layer,
The first birefringent layer is disposed between the first polarizer and the liquid crystal cell,
The refractive index of the first birefringent layer has a relationship of nx = ny> nz,
The second polarizing plate includes a second polarizer and a second birefringent layer,
The second birefringent layer is disposed between the second polarizer and the liquid crystal cell,
In the liquid crystal panel showing a relationship of nx> ny ≧ nz, the refractive index of the second birefringent layer is as follows:
The first polarizing plate is the polarizing plate of the present invention, and the optical film contained in the polarizing plate of the present invention is the first birefringent layer.

  The liquid crystal display device of the present invention is a liquid crystal display device including an optical member or a liquid crystal panel, wherein the optical member is the optical film of the present invention or the polarizing plate of the present invention, and the liquid crystal panel is the book of the present invention. It is the liquid crystal panel of the invention.

  According to the method for producing an optical film of the present invention, since the axial accuracy of the obtained optical film can be improved and the alignment axis can be made uniform, an optical film capable of imparting excellent contrast characteristics to an image display device or the like. Can be provided. In particular, it is possible to effectively equalize the variation in the degree of polarization at both ends of the optical film in the width direction of the original film, so that the production efficiency can be greatly improved and the screen size of the image display device can be increased. An optical film can be obtained.

  In the method for producing an optical film of the present invention, the step of forming the birefringent layer is preferably a step of applying a material containing a non-liquid crystalline material.

  In the method for producing an optical film of the present invention, the non-liquid crystalline material is preferably at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide.

  In the method for producing an optical film of the present invention, the transparent film is preferably triacetyl cellulose.

  In the method for producing an optical film of the present invention, the stretching temperature of the transparent film in the step of homogenizing the orientation axis is preferably in the range of 120 to 200 ° C.

  Next, the present invention will be described in detail. However, the present invention is not limited by the following description.

  In the manufacturing method of the optical film of this invention, it has the equalization process of the orientation axis | shaft which extends | stretches a transparent film by the draw ratio of the range of 1.05-1.25 times in the width direction. The draw ratio is preferably in the range of 1.05 to 1.20 times. If the draw ratio exceeds 1.25 times, the film may be broken. On the other hand, if the draw ratio is less than 1.05, the orientation axis cannot be sufficiently uniformized.

  In the present invention, the refractive index “nx” is a refractive index in a direction (slow axis direction) in which the in-plane refractive index of the layer (birefringent layer, film, liquid crystal cell, etc. is the same) is maximum. The refractive index “ny” is a refractive index in a direction (fast axis direction) orthogonal to the nx direction in the plane of the layer. The refractive index “nz” is the refractive index in the thickness direction of the layer orthogonal to the nx and ny directions.

  The in-plane retardation value (Re [λ]) of the layer is, for example, an in-plane retardation value at a wavelength λ (nm) at 23 ° C. Re [λ] is calculated by the formula: Re [λ] = (nx−ny) × d, where d (nm) is the thickness of the layer. Re [λ] can be measured, for example, by the method described in Examples described later.

  The layer thickness direction retardation value (Rth [λ]) is, for example, a layer thickness direction retardation value at a wavelength λ (nm) at 23 ° C. Rth [λ] is calculated by the formula: Rth [λ] = (nx−nz) × d, where d (nm) is the thickness of the layer. Rth [λ] can be measured, for example, by the method described in Examples described later.

  The Nz coefficient is a value calculated also by the formula: Nz coefficient = Rth [λ] / Re [λ]. The λ can be set to 590 nm, for example.

  In the present invention, “nx = ny” or “ny = nz” includes not only the case where they completely match, but also the case where they are substantially the same. Therefore, for example, the description of nx = ny includes the case where Re [590] is less than 10 nm.

  In the present invention, the term “orthogonal” includes the case of being substantially orthogonal, and the case of being substantially orthogonal is, for example, a range of 90 ° ± 2 °, and preferably 90 °. The range is ± 1 °. Further, in the present invention, the term “parallel” includes a case of being substantially parallel, and the case of being substantially parallel is, for example, a range of 0 ° ± 2 °, and preferably 0 ° ± 1. It is in the range of °.

[Transparent film]
The material for forming the transparent film is not particularly limited, but a polymer having excellent transparency is preferable, and a thermoplastic resin is preferable because it is suitable for stretching treatment as described later. Specifically, for example, acetate resin such as triacetyl cellulose (TAC), polyester resin, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin And polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin, and mixtures thereof. A liquid crystal polymer or the like can also be used. Further, for example, as described in JP-A-2001-343529 (WO 01/37007), a thermoplastic resin having a substituted imide group or an unsubstituted imide group in the side chain, and a substituted phenyl group in the side chain Alternatively, a mixture of a thermoplastic resin having an unsubstituted phenyl group and a nitrile group can also be used. Specific examples include a resin composition having an alternating copolymer composed of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer. Among these forming materials, for example, a material capable of setting the birefringence index relatively lower when a transparent film is formed is preferable, and specifically, a substituted imide group or an unsubstituted imide group in the aforementioned side chain. And a mixture of a thermoplastic resin having a substituted phenyl group or an unsubstituted phenyl group and a nitrile group in the side chain.

  The thickness of the transparent film is not particularly limited, but is, for example, in the range of 10 to 200 μm, preferably in the range of 20 to 150 μm, and particularly preferably in the range of 30 to 100 μm.

  The step of homogenizing the orientation axis of the transparent film is performed in a range of a draw ratio of 1.05 to 1.25 by a fixed end lateral stretching method in which the longitudinal direction of the transparent film is fixed and uniaxially stretched in the width direction. By having the said process, the optical characteristic of the optical film obtained becomes more uniform, and especially the dispersion | variation in the characteristic of the original fabric width direction of an optical film can be prevented effectively. Therefore, the optical film obtained as described above can cope with the enlargement of the screen of the liquid crystal display device.

  As the transparent film, it is preferable to use a TAC film because it is excellent in transparency and workability. In the case of a TAC film, the thickness direction retardation value (Rth) is about 40 nm and is large at a thickness of 40 μm. For a cellulose-based film such as TAC having a large thickness direction retardation value (Rth), it is preferable to perform an appropriate treatment for reducing the thickness direction retardation (Rth).

  Any appropriate processing method can be adopted as the processing for reducing the retardation (Rth) in the thickness direction. For example, a base material such as polyethylene terephthalate (PET), polypropylene, or stainless steel coated with a solvent such as cyclopentanone or methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at about 80 to 150 ° C., 3 10 minutes) and then peeling the base film; applying a solution of norbornene resin, acrylic resin, etc. dissolved in a solvent such as cyclopentanone, methyl ethyl ketone, etc. to a general cellulose film and heating Examples include a method of peeling the coated film after drying (for example, about 80 to 150 ° C. for about 3 to 10 minutes).

  The material constituting the cellulose film is preferably an aliphatic substituted cellulose polymer such as diacetyl cellulose or TAC. In TAC generally used, the degree of acetic acid substitution is about 2.8, but the degree of acetic acid substitution is preferably in the range of 1.8 to 2.7, more preferably the degree of propionic acid substitution is 0. The thickness direction retardation value (Rth) can be controlled to be small by controlling in the range of .1-1.

  The techniques for controlling the thickness direction retardation value (Rth) as described above may be used in appropriate combination.

  The stretching temperature of the transparent film in the step of homogenizing the orientation axis is preferably in the range of 120 to 200 ° C. The stretching temperature is preferably in the range of 130 to 180 ° C, more preferably in the range of 140 to 160 ° C. When the stretching temperature is less than 120 ° C., for example, when the transparent film is TAC, stretching is difficult and the film is easily broken. When the temperature exceeds 200 ° C., the plasticizer contained in the transparent film may be detached. Therefore, the transparent film tends to be brittle.

[Birefringent layer]
The step of forming a birefringent layer in the present invention is preferably a step of applying a material containing a non-liquid crystalline material to the transparent film as a birefringent layer forming material. Such a non-liquid crystal material is different from the liquid crystal material, for example, and forms a film exhibiting optical uniaxial properties of nx> nz and ny> nz by its own property regardless of the orientation of the transparent film. To do. For this reason, for example, the transparent film to be used is not limited to an oriented film. For example, even if it is an unoriented film, a process of applying an oriented film on the surface, a process of laminating an oriented film, etc. Can be omitted.

  As the non-liquid crystalline material, a non-liquid crystalline polymer is preferably used. For example, polyamide, polyimide, polyester, polyetherketone, polyamideimide are excellent in heat resistance, chemical resistance, transparency, and rigidity. It is preferable to use at least one polymer material selected from the group consisting of polyesterimide and polyesterimide. Any one of these polymers may be used alone, or a mixture of two or more having different functional groups such as a mixture of polyaryletherketone and polyamide may be used. . Among such polymers, polyimide is particularly preferable because of its high transparency, high orientation, and high stretchability. When the polyimide is formed into a sheet by the solvent casting method, the molecules are likely to spontaneously orientate during the evaporation of the solvent, so the ellipse shows the relationship of nx = ny> nz (negative uniaxiality). The retardation film can be made very thin.

  Although the molecular weight of the polymer is not particularly limited, for example, 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. is there.

  As the polyimide, for example, a polyimide that has high in-plane orientation and is soluble in an organic solvent is preferable. Specifically, for example, it includes a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A, and has the following formula ( A polymer containing one or more repeating units shown in 1) can be used.

In the formula (1), R ^{3 to} R ⁶ are each selected from hydrogen, halogen, a phenyl group, a phenyl group substituted with ₁ to 4 halogen atoms or a C ₁ to ₁₀ alkyl group, and a C ₁ to ₁₀ alkyl group. And at least one substituent selected independently from the group. ^Preferably, R 3 to R ⁶ is a halogen, a phenyl group, each independently from the group consisting of one to four halogen atoms or _C 1 _{~ 10} alkyl-substituted phenyl, and _C 1 _{~ 10} alkyl group It is at least one type of substituent selected.

In the formula (1), Z represents a tetravalent aromatic group C ₆ ~ _20, preferably a pyromellitic group, a polycyclic aromatic group, a derivative of a polycyclic aromatic group, or, It is group represented by following formula (2).

In the formula (2), Z ′ is, for example, a covalent bond, C (R ⁷ ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, or NR ^Eight groups, and when there are a plurality of groups, they are the same or different. W represents an integer from 1 to 10. Each R ⁷ is independently hydrogen or C (R ⁹ ) ₃ . R ⁸ is hydrogen, an alkyl group or a _C 6 _{~ 20} aryl group, the carbon atom number from 1 to about 20, for a plurality, it may be the same or different. Each R ⁹ is independently hydrogen, fluorine, or chlorine.

Examples of the polycyclic aromatic group include a tetravalent group derived from naphthalene, fluorene, benzofluorene or anthracene. The substitution Examples of the substituted derivatives of polycyclic aromatic group, for example, an alkyl group of C ₁ ~ _10, at least one group selected from the group consisting of fluorinated derivatives, and F or a halogen such as Cl And the above-mentioned polycyclic aromatic group.

  In addition, for example, a homopolymer described in JP-A-8-511812, wherein the repeating unit is represented by the following general formula (3) or (4), or the repeating unit is represented by the following general formula (5): The polyimide etc. which are shown are mention | raise | lifted. In addition, the polyimide of following formula (5) is a preferable form of the homopolymer of following formula (3).

In the general formulas (3) to (5), G and G ′ are, for example, a covalent bond, a CH ₂ group, a C (CH ₃ ) ₂ group, a C (CF ₃ ) ₂ group, or a C (CX ₃ ) ₂ group. (Where X is halogen), from the group consisting of CO, O, S, SO ₂ , Si (CH ₂ CH ₃ ) ₂ and N (CH ₃ ) groups, respectively It represents independently selected groups, and may be the same or different.

In the above formulas (3) and (5), L is a substituent, and d and e represent the number of substitutions. L is, for example, a halogen, a C _1-3 alkyl group, a C _1-3 halogenated alkyl group, a phenyl group, or a substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituted phenyl group include substituted phenyl groups having at least one substituent selected from the group consisting of halogen, C _1-3 alkyl groups, and C _1-3 halogenated alkyl groups. Examples of the halogen include fluorine, chlorine, bromine and iodine. d is an integer from 0 to 2, and e is an integer from 0 to 3.

  In the formulas (3) to (5), Q is a substituent, and f represents the number of substitutions. Q is, for example, selected from the group consisting of hydrogen, halogen, alkyl group, substituted alkyl group, nitro group, cyano group, thioalkyl group, alkoxy group, aryl group, substituted aryl group, alkyl ester group, and substituted alkyl ester group And when Q is plural, they are the same or different. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted alkyl group include a halogenated alkyl group. Examples of the substituted aryl group include a halogenated aryl group. f is an integer from 0 to 4, and g and h are integers from 0 to 3 and 1 to 3, respectively. Further, g and h are preferably larger than 1.

In the formula (4), R ¹⁰ and R ¹¹ are groups independently selected from the group consisting of hydrogen, halogen, phenyl group, substituted phenyl group, alkyl group, and substituted alkyl group. Among these, R ¹⁰ and R ¹¹ are preferably each independently a halogenated alkyl group.

In the formula (5), M ¹ and M ² are the same or different and are, for example, a halogen, a C _1-3 alkyl group, a C _1-3 halogenated alkyl group, a phenyl group, or a substituted phenyl group. is there. Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the substituted phenyl group include substituted phenyl groups having at least one type of substituent selected from the group consisting of halogen, C _1-3 alkyl groups, and C _1-3 halogenated alkyl groups. .

Specific examples of the polyimide represented by the formula (3) include those represented by the following formula (6).

  Furthermore, examples of the polyimide include a copolymer obtained by appropriately copolymerizing an acid dianhydride other than the skeleton (repeating unit) as described above and a diamine.

  Examples of the acid dianhydride include aromatic tetracarboxylic dianhydrides. Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, heterocyclic aromatic tetracarboxylic dianhydride, 2, And 2'-substituted biphenyltetracarboxylic dianhydride.

  Examples of the pyromellitic dianhydride include pyromellitic dianhydride, 3,6-diphenylpyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyromellitic dianhydride, and 3,6-dibromo. Examples include pyromellitic dianhydride and 3,6-dichloropyromellitic dianhydride. Examples of the benzophenone tetracarboxylic dianhydride include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 2 , 2 ′, 3,3′-benzophenonetetracarboxylic dianhydride and the like. Examples of the naphthalenetetracarboxylic dianhydride include 2,3,6,7-naphthalene-tetracarboxylic dianhydride, 1,2,5,6-naphthalene-tetracarboxylic dianhydride, 2,6 -Dichloro-naphthalene-1,4,5,8-tetracarboxylic dianhydride and the like. Examples of the heterocyclic aromatic tetracarboxylic dianhydride include thiophene-2,3,4,5-tetracarboxylic dianhydride and pyrazine-2,3,5,6-tetracarboxylic dianhydride. Pyridine-2,3,5,6-tetracarboxylic dianhydride and the like. Examples of the 2,2′-substituted biphenyltetracarboxylic dianhydride include 2,2′-dibromo-4,4 ′, 5,5′-biphenyltetracarboxylic dianhydride and 2,2′-dichloro. -4,4 ', 5,5'-biphenyltetracarboxylic dianhydride, 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride, etc. can give.

  Other examples of the aromatic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) methane dianhydride. Bis (2,5,6-trifluoro-3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 3-hexafluoropropane dianhydride, 4,4 ′-(3,4-dicarboxyphenyl) -2,2-diphenylpropane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4 , 4′-oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic dianhydride (3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride), 4,4 ′ -[4,4'-I Propylidene-di (p-phenyleneoxy)] bis (phthalic anhydride), N, N- (3,4-dicarboxyphenyl) -N-methylamine dianhydride, bis (3,4-dicarboxyphenyl) And diethylsilane dianhydride.

  Among these, the aromatic tetracarboxylic dianhydride is preferably 2,2′-substituted biphenyltetracarboxylic dianhydride, more preferably 2,2′-bis (trihalomethyl) -4,4. ', 5,5'-biphenyltetracarboxylic dianhydride, more preferably 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic dianhydride It is.

  Examples of the diamine include aromatic diamines, and specific examples include benzene diamine, diaminobenzophenone, naphthalene diamine, heterocyclic aromatic diamines, and other aromatic diamines.

  Examples of the benzenediamine include o-, m- and p-phenylenediamine, 2,4-diaminotoluene, 1,4-diamino-2-methoxybenzene, 1,4-diamino-2-phenylbenzene, and 1, Examples include diamines selected from the group consisting of benzenediamines such as 3-diamino-4-chlorobenzene. Examples of the diaminobenzophenone include 2,2'-diaminobenzophenone and 3,3'-diaminobenzophenone. Examples of the naphthalene diamine include 1,8-diaminonaphthalene and 1,5-diaminonaphthalene. Examples of the heterocyclic aromatic diamine include 2,6-diaminopyridine, 2,4-diaminopyridine, and 2,4-diamino-S-triazine.

  In addition to these, as the aromatic diamine, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylmethane, 4,4 ′-(9-fluorenylidene) -dianiline, 2,2′-bis ( Trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2′-dichloro-4,4′-diaminobiphenyl, 2,2 ′, 5 5′-tetrachlorobenzidine, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1, 1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,3-bis (3-aminophen Xyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3 , 3,3-hexafluoropropane, 4,4′-diaminodiphenylthioether, 4,4′-diaminodiphenylsulfone, and the like.

  Examples of the polyether ketone which is a material for forming the birefringent layer include polyaryl ether ketones represented by the following general formula (7) described in JP-A No. 2001-49110.

  In the formula (7), X represents a substituent, and q represents the number of substitutions. X is, for example, a halogen atom, a lower alkyl group, a halogenated alkyl group, a lower alkoxy group, or a halogenated alkoxy group, and when there are a plurality of Xs, they are the same or different.

Examples of the halogen atom include a fluorine atom, a bromine atom, a chlorine atom, and an iodine atom, and among these, a fluorine atom is preferable. Examples of the lower alkyl group, for example, preferably a lower alkyl group having a straight-chain or branched C ₁ ~ _6, more preferably a straight-chain or branched alkyl group of C ₁ ~ _4. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group are preferable, and a methyl group and an ethyl group are particularly preferable. Examples of the halogenated alkyl group include halides of the lower alkyl group such as a trifluoromethyl group. Examples of the lower alkoxy group, for example, preferably a straight chain or branched chain alkoxy group of C ₁ ~ _6, more preferably a straight chain or branched chain alkoxy group of C ₁ ~ _4. Specifically, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group are more preferable, and a methoxy group and an ethoxy group are particularly preferable. . Examples of the halogenated alkoxy group include halides of the lower alkoxy group such as a trifluoromethoxy group.

  In the formula (7), q is an integer from 0 to 4. In the above formula (7), it is preferable that q = 0 and that the carbonyl group bonded to both ends of the benzene ring and the oxygen atom of the ether are present in the para position.

In the formula (7), R ¹ is a group represented by the following formula (8), and m is an integer of 0 or 1.

In the formula (8), X ′ represents a substituent, and is the same as X in the formula (7), for example. In the formula (8), when there are a plurality of X ′, they are the same or different. q ′ represents the number of substitutions of X ′ and is an integer from 0 to 4, preferably q ′ = 0. P is an integer of 0 or 1.

In the above formula (8), ^{R 2} represents a divalent aromatic group. Examples of the divalent aromatic group include an o-, m- or p-phenylene group, or naphthalene, biphenyl, anthracene, o-, m- or p-terphenyl, phenanthrene, dibenzofuran, biphenyl ether, or And divalent groups derived from biphenylsulfone. In these divalent aromatic groups, hydrogen directly bonded to the aromatic group may be substituted with a halogen atom, a lower alkyl group or a lower alkoxy group. Among these, as R ² , an aromatic group selected from the group consisting of the following formulas (9) to (15) is preferable.

In the formula (7), R ¹ is preferably a group represented by the following formula (16). In the following formula (16), R ² and p have the same meanings as the formula (8).

  Furthermore, in said Formula (7), n represents a polymerization degree, for example, is the range of 2-5000, Preferably, it is the range of 5-500. Further, the polymerization may be composed of repeating units having the same structure, or may be composed of repeating units having different structures. In the latter case, the polymerization mode of the repeating unit may be block polymerization or random polymerization.

  Furthermore, the end of the polyaryl ether ketone represented by the formula (7) is preferably fluorine on the p-tetrafluorobenzoylene group side and a hydrogen atom on the oxyalkylene group side. For example, it can be represented by the following general formula (17). In the following formula, n represents the same degree of polymerization as in formula (7).

  Specific examples of the polyaryletherketone represented by the formula (7) include those represented by the following formulas (18) to (21). In each formula below, n represents the formula (7). Represents the same degree of polymerization.

  In addition to these, examples of the polyamide or polyester that is the material for forming the birefringent layer include polyamides and polyesters described in JP-T-10-508048, and their repeating units are: For example, it can be represented by the following general formula (22).

In the formula (22), Y is O or NH. E is, for example, a covalent bond, a C ₂ alkylene group, a halogenated C ₂ alkylene group, a CH ₂ group, a C (CX ₃ ) ₂ group (where X is a halogen or hydrogen), a CO group, It is at least one kind of group selected from the group consisting of O atom, S atom, SO ₂ group, Si (R) ₂ group, and N (R) group, and may be the same or different. In E, R is at least one of a C _1-3 alkyl group and a C _1-3 halogenated alkyl group, and is in a meta position or a para position with respect to a carbonyl functional group or a Y group.

  Moreover, in said (22), A and A 'are substituents, and t and z represent the number of each substitution. P is an integer from 0 to 3, q is an integer from 1 to 3, and r is an integer from 0 to 3.

A is, for example, an alkoxy group represented by hydrogen, halogen, C _1-3 alkyl group, C _1-3 halogenated alkyl group, OR (where R is as defined above), aryl Group, substituted aryl group by halogenation, C _1-9 alkoxycarbonyl group, C _1-9 alkylcarbonyloxy group, C _1-12 aryloxycarbonyl group, C _1-12 arylcarbonyloxy group and substituted derivatives thereof, C It is selected from the group consisting of a _1-12 arylcarbamoyl group and a C _1-12 arylcarbonylamino group and substituted derivatives thereof, and in the plurality of cases, they are the same or different. The A ′ is, for example, selected from the group consisting of halogen, a C _1-3 alkyl group, a C _1-3 halogenated alkyl group, a phenyl group, and a substituted phenyl group, and in a plurality of cases, they are the same or different. Examples of the substituent on the phenyl ring of the substituted phenyl group include halogen, a C _1-3 alkyl group, a C _1-3 halogenated alkyl group, and combinations thereof. The t is an integer from 0 to 4, and the z is an integer from 0 to 3.

Among the repeating units of polyamide or polyester represented by the formula (22), those represented by the following general formula (23) are preferable.

  In the formula (23), A, A ′ and Y are as defined in the formula (22), and v is an integer from 0 to 3, preferably an integer from 0 to 2. x and y are each 0 or 1, but are not 0 at the same time.

[Formation of birefringent layer]
The method for coating the material for forming the birefringent layer on the transparent film that has undergone the alignment axis homogenization step is not particularly limited. For example, the non-liquid crystalline polymer as described above is heated and melted for coating. And a method of coating a polymer solution in which the non-liquid crystalline polymer is dissolved in a solvent. Among them, the method of applying the polymer solution is preferable because of excellent workability.

  The polymer concentration in the polymer solution is not particularly limited. For example, since the viscosity is easy to apply, for example, the non-liquid crystalline polymer may be 5 to 50 parts by weight with respect to 100 parts by weight of the solvent. The amount is preferably 10 to 40 parts by weight.

  The solvent of the polymer solution is not particularly limited as long as the forming material such as the non-liquid crystalline polymer can be dissolved, and can be appropriately determined according to the type of the forming material. Specific examples include, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, Aromatic hydrocarbons such as xylene, methoxybenzene, 1,2-dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; Ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, die Alcohol solvents such as lenglycol 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. One type of these solvents may be used, or two or more types may be used in combination.

  For example, the polymer solution may further contain various additives such as a stabilizer, a plasticizer, and metals as required.

  The polymer solution may contain other different resins as long as the orientation of the forming material is not significantly lowered. Examples of the other resin include various general-purpose resins, engineering plastics, thermoplastic resins, and thermosetting resins.

  Examples of the general-purpose resin include polyethylene (PE), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), ABS resin, and AS resin. Examples of the engineering plastic include polyacetate (POM), polycarbonate (PC), polyamide (PA: nylon), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the thermoplastic resin include polyphenylene sulfide (PPS), polyethersulfone (PES), polyketone (PK), polyimide (PI), polycyclohexanedimethanol terephthalate (PCT), polyarylate (PAR), and liquid crystal polymer. (LCP) and the like. Examples of the thermosetting resin include an epoxy resin and a phenol novolac resin.

  Thus, when mix | blending said other resin etc. in the said polymer solution, the compounding quantity is 0-50 mass% with respect to the said polymer material, for example, Preferably, 0-30 mass% It is.

  Examples of the coating method for the polymer solution include spin coating, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing. Moreover, in the case of coating, the superposition | polymerization method of a polymer layer is also employable as needed.

  According to the method for producing an optical film of the present invention, it is possible to obtain an optical film having an optical characteristic in which the refractive index satisfies the relationship of nx = ny> nz. Here, nx = ny includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. In the present specification, for example, “nx and ny are substantially equal” is intended to include the case where nx and ny are different from each other as long as the overall optical characteristics of the optical film are not practically affected.

[Polarizing plate of the present invention]
The polarizing plate of the present invention is a polarizing plate including an optical film and a polarizer, and the optical film is the optical film of the present invention. As a configuration of the polarizing plate of the present invention, a polarizer is laminated on the transparent film side or the birefringent layer side constituting the optical film. In addition, the laminated body of the said birefringent layer single layer which peeled the said birefringent layer from the said transparent film, and a polarizer can also be used as a polarizing plate. A protective layer may be formed on the polarizer. An example of the configuration of the polarizing plate of the present invention is shown in the schematic cross-sectional view of FIG. In the figure, the size, ratio, and the like of each component are different from actual ones for easy understanding. As shown in the figure, the polarizing plate 10 is formed by laminating a protective layer 11, a polarizer 12, and the optical film 13 of the present invention in this order. The total thickness of the polarizing plate is, for example, in the range of 20 to 300 μm. By setting it as the thickness of the said range, the polarizing plate which was more excellent in mechanical strength can be obtained.

  Arbitrary adhesive layers and arbitrary optical members (preferably those exhibiting isotropic properties) may be disposed between the constituent members (optical members) of the polarizing plate. The “adhesive layer” refers to a layer that joins the surfaces of adjacent optical members and integrates them with practically sufficient adhesive force and adhesion time. Examples of the material for forming the adhesive layer include conventionally known adhesives, pressure-sensitive adhesives, anchor coating agents, and the like. The adhesive layer may have a multilayer structure in which an anchor coat layer is formed on the surface of an adhesive body and an adhesive layer is formed thereon. Further, it may be a thin layer (also referred to as a hairline) that cannot be visually recognized.

  The polarizer can be obtained, for example, by stretching a polymer film containing a polyvinyl alcohol resin containing iodine. The iodine content of the polarizer is, for example, in the range of 1.8 to 5.0% by weight, and preferably in the range of 2.0 to 4.0% by weight. The polarizer preferably further contains potassium. The potassium content is, for example, in the range of 0.2 to 1.0% by weight, preferably in the range of 0.3 to 0.9% by weight, and more preferably in the range of 0.4 to 0.00. It is in the range of 8% by weight. The polarizer preferably further contains boron. The boron content is, for example, in the range of 0.5 to 3.0% by weight, preferably in the range of 1.0 to 2.8% by weight, and more preferably in the range of 1.5 to 2.%. It is in the range of 6% by weight.

  The polyvinyl alcohol resin can be obtained, for example, by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer. The degree of saponification of the polyvinyl alcohol resin is preferably in the range of 95.0 to 99.9 mol%. By using a polyvinyl alcohol-based resin having a saponification degree within the above range, a polarizer having more excellent durability can be obtained. The average degree of polymerization of the polyvinyl alcohol-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is preferably in the range of 1200 to 3600. The average degree of polymerization can be determined according to, for example, JIS K 6726 (1994 edition).

  As a method for obtaining the polymer film containing the polyvinyl alcohol-based resin, any appropriate forming method can be adopted. Examples of the forming method include the method described in JP 2000-315144 A [Example 1].

  The polymer film containing the polyvinyl alcohol resin preferably contains at least one of a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. The content of the plasticizer and the surfactant is preferably in the range of 1 to 10 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. For example, the plasticizer and the surfactant improve the dyeability and stretchability of the polarizer.

  As the polymer film containing the polyvinyl alcohol-based resin, for example, a commercially available film can be used as it is. Examples of the polymer film containing the commercially available polyvinyl alcohol resin include, for example, “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., “Tose Cello Vinylon Film” manufactured by Tosero Co., Ltd., Nippon Synthetic Chemical Industry The product name "Nippon Vinylon Film" manufactured by Co., Ltd. and the like can be mentioned.

  The protective layer is used, for example, to prevent the polarizer from contracting or expanding, or to prevent deterioration due to ultraviolet rays. The thickness of the protective layer is preferably in the range of 20 to 100 μm. The transmittance (T [590]) at a wavelength of 590 nm of the protective layer is preferably 90% or more.

  Any appropriate material can be selected as the material for forming the protective layer. The protective layer is preferably a polymer film containing a cellulose resin, a norbornene resin, or an acrylic resin. The polymer film containing the cellulose resin can be obtained, for example, by the method described in Example 1 of JP-A-7-112446. The polymer film containing the norbornene resin can be obtained, for example, by the method described in JP-A-2001-350017. The polymer film containing the acrylic resin can be obtained, for example, by the method described in Example 1 of JP-A-2004-19892.

  The protective layer may have a surface treatment layer on the side opposite to the polarizer side. As the surface treatment, an appropriate treatment can be appropriately employed depending on the purpose. Examples of the surface treatment layer include treatment layers such as hard coat treatment, antistatic treatment, antireflection treatment (also referred to as antireflection treatment), and diffusion treatment (also referred to as antiglare treatment). These surface treatments are used for the purpose of preventing the screen from becoming dirty or damaged, or preventing the display screen from becoming difficult to see due to the reflection of indoor fluorescent light or sunlight on the screen. In general, the surface treatment layer is used in which a treatment agent for forming the treatment layer is fixed on the surface of a base film. The base film may also serve as the protective layer. Further, the surface treatment layer may have a multilayer structure in which a hard coat treatment layer is laminated on an antistatic treatment layer, for example.

  As the protective layer, for example, a commercially available polymer film subjected to surface treatment can be used as it is. Alternatively, the commercially available polymer film can be used after being subjected to any surface treatment. Examples of the commercially available film subjected to the diffusion treatment (anti-glare treatment) include trade names “AG150”, “AGS1”, “AGS2” manufactured by Nitto Denko Corporation. Examples of commercially available films subjected to the antireflection treatment (anti-reflection treatment) include trade names “ARS” and “ARC” manufactured by Nitto Denko Corporation. Examples of the commercially available film subjected to the hard coat treatment and the antistatic treatment include trade name “KC8UX-HA” manufactured by Konica Minolta Opto Co., Ltd. Examples of the commercially available film subjected to the antireflection treatment include a product name “ReoLook series” manufactured by NOF Corporation.

[First LCD panel]
As described above, the first liquid crystal panel of the present invention is a liquid crystal panel including a liquid crystal cell and an optical member, and the optical member is the optical film of the present invention or the polarizing plate of the present invention, An optical member is disposed on at least one side of the liquid crystal cell. An example of the configuration of the first liquid crystal panel of the present invention is shown in the schematic cross-sectional view of FIG. In this figure, the same parts as those in FIG. As shown in the figure, in the first liquid crystal panel 30, the polarizing plate 10 of the present invention is in a state in which the optical film 13 is located on the liquid crystal cell 41 side (the upper side in the figure). ) And the backlight side (lower side in the figure). In the first liquid crystal panel of this example, the polarizing plate of the present invention is arranged on both the viewing side and the backlight side of the liquid crystal cell. However, the present invention is not limited to this. In the first liquid crystal panel of the present invention, the polarizing plate of the present invention may be disposed on at least one of the viewing side and the backlight side of the liquid crystal cell.

  Examples of the liquid crystal cell include an active matrix type using a thin film transistor. Examples of the liquid crystal cell include a simple matrix type as employed in a super twist nematic liquid crystal display device.

  The liquid crystal cell generally has a configuration in which a liquid crystal layer is sandwiched between a pair of substrates. FIG. 4 shows an example of the configuration of the liquid crystal cell. As illustrated, in the liquid crystal cell 41 of this example, a spacer 412 is disposed between a pair of substrates 411 so that a space is formed, and a liquid crystal layer 413 is sandwiched in the space. Although not shown, one of the pair of substrates (active matrix substrate) has, for example, a switching element (for example, TFT) for controlling the electro-optical characteristics of the liquid crystal, and scanning that applies a gate signal to the active element. Lines and signal lines that carry source signals are provided. For example, a color filter is provided on the other of the pair of substrates.

  The color filter may be provided on the active matrix substrate. Or, for example, when an RGB three-color light source (which may further include a multicolor light source) is used as the illumination means of the liquid crystal display device as in the field sequential method, the color filter is omitted. Also good. The distance (cell gap) between the pair of substrates is controlled by a spacer, for example. The cell gap is, for example, in the range of 1.0 to 7.0 μm. For example, an alignment film made of polyimide is provided on the side of each substrate in contact with the liquid crystal layer. Alternatively, for example, when the initial alignment of liquid crystal molecules is controlled using a fringe electric field formed by a patterned transparent substrate, the alignment film may be omitted.

  The refractive index of the liquid crystal cell preferably shows a relationship of nz> nx = ny. As the liquid crystal cell having a refractive index of nz> nx = ny, according to the drive mode classification, for example, vertical alignment (VA) mode, twisted nematic (TN) mode, vertical alignment type electric field control Birefringence (ECB) mode, optical compensation birefringence (OCB) mode, etc. are mentioned. In the present invention, the driving mode of the liquid crystal cell is preferably the VA mode.

  Rth [590] of the liquid crystal cell in the absence of an electric field is preferably in the range of −500 to −200 nm, more preferably in the range of −400 to −200 nm. The Rth [590] is appropriately set by adjusting the birefringence of the liquid crystal molecules and the cell gap, for example.

  The VA mode liquid crystal cell uses a voltage-controlled birefringence effect to cause liquid crystal molecules aligned in a homeotropic alignment to respond to the substrate with an electric field in a normal direction in the absence of an electric field. Specifically, as described in, for example, Japanese Patent Application Laid-Open No. 62-210423 and Japanese Patent Application Laid-Open No. 4-153621, in the case of a normally black method, liquid crystal molecules are formed on a substrate in the absence of an electric field. Therefore, when the upper and lower polarizing plates are arranged orthogonally, black display can be obtained. On the other hand, in the presence of an electric field, the liquid crystal molecules operate so as to tilt in a 45 ° azimuth direction with respect to the absorption axis of the polarizing plate, whereby the transmittance increases and white display is obtained.

  The VA mode liquid crystal cell can be made multi-domain by using a substrate in which slits are formed on electrodes or a substrate on which protrusions are formed on the surface as described in JP-A-11-258605, for example. It may be what you did. Such a liquid crystal cell is, for example, a product name “ASV (Advanced Super View) mode” manufactured by Sharp Corporation, a product name “CPA (Continuous Pinwheel Alignment) mode” manufactured by the same company, and a product name manufactured by Fujitsu Limited. "MVA (Multi-domain Vertical Alignment) mode", product name "PVA (Patterned Vertical Alignment) mode" manufactured by Samsung Electronics Co., Ltd. "SURVIVE (Super Ranged Viewing Vertical Alignment) mode" and the like.

  In the present invention, it is also preferable that the driving mode of the liquid crystal panel is an in-plane switching (IPS) mode.

  The IPS mode liquid crystal cell uses a voltage controlled birefringence (ECB) effect and liquid crystal molecules that are homogeneously aligned in the absence of an electric field, for example, a counter electrode and a pixel electrode formed of metal. The substrate is caused to respond with an electric field (also referred to as a transverse electric field) parallel to the substrate. More specifically, for example, Techno Times Publishing “Monthly Display July” p. 83-p. 88 (1997 edition) and “Liquid Crystal vol.2 No. 4” published by the Japanese Liquid Crystal Society. 303-p. 316 (1998 edition), in the normally black method, the alignment direction of the liquid crystal cell when no electric field is applied is aligned with the absorption axis of the polarizer on one side so that the upper and lower polarizing plates are If they are arranged orthogonally, the display is completely black without an electric field. When an electric field is present, the transmittance according to the rotation angle can be obtained by rotating the liquid crystal molecules while keeping them parallel to the substrate. The IPS mode includes a super-in-plane switching (S-IPS) mode and an advanced super-in-plane switching (AS-IPS) mode employing a V-shaped electrode or a zigzag electrode.

  The homogeneously aligned liquid crystal molecules are those in which the alignment vector of the liquid crystal molecules is aligned in parallel and uniformly with respect to the substrate plane as a result of the interaction between the aligned substrate and the liquid crystal molecules. In the present specification, the case where the alignment vector is slightly inclined with respect to the substrate plane, that is, the case where the liquid crystal molecules have a pretilt is also included in the homogeneous alignment. When the liquid crystal molecules have a pretilt, the pretilt angle is preferably 20 ° or less from the viewpoint of maintaining a high contrast ratio and obtaining good display characteristics. As the nematic liquid crystal, any appropriate nematic liquid crystal can be adopted depending on the purpose. For example, the nematic liquid crystal may have a positive or negative dielectric anisotropy. A specific example of a nematic liquid crystal having a positive dielectric anisotropy is a product name “ZLI-4535” manufactured by Merck & Co., Inc. A specific example of a nematic liquid crystal having a negative dielectric anisotropy is a product name “ZLI-2806” manufactured by Merck & Co., Inc.

  As the liquid crystal cell, for example, a liquid crystal cell mounted on a commercially available liquid crystal display device may be used as it is. As a commercially available liquid crystal display device including the VA mode liquid crystal cell, for example, a product name “AQUAS series” of a liquid crystal television manufactured by Sharp Corporation, a product name “BRAVIA series” of a liquid crystal television manufactured by Sony Corporation, and 32V manufactured by Samsunung Corporation. The product name “LN32R51B” of the type wide liquid crystal television, the product name “FORIS SC26XD1” of the liquid crystal television manufactured by Nanao Co., Ltd., the product name “T460HW01” of the liquid crystal television manufactured by AU Optronics, and the like. As a commercially available liquid crystal display device including the IPS mode liquid crystal cell, for example, as a commercially available liquid crystal display device adopting the IPS mode as described above, for example, a trade name of Hitachi, Ltd. 20V type wide liquid crystal television. "Wooo", Eyama 19 type liquid crystal display trade name "ProLite E481S-1", Nanao Corporation 17 type TFT liquid crystal display trade name "FlexScan L565" and the like.

[Second LCD panel]
An example of the configuration of the second liquid crystal panel of the present invention is shown in the schematic cross-sectional view of FIG. In this figure, the same parts as those in FIG. As shown in the drawing, the second liquid crystal panel 40 includes a first polarizing plate 10, a second polarizing plate 20, and a liquid crystal cell 41 as main constituent members. The first polarizing plate 10 is the polarizing plate 10 of the present invention. In the first polarizing plate 10, the protective layer 11 is the first protective layer 11, the polarizer 12 is the first polarizer 12, and the optical film 13 is the first birefringence. Layer 13. The second polarizing plate 20 includes a second protective layer 21, a second polarizer 22, and a second birefringent layer 23 stacked in this order. The first polarizing plate 10 is disposed on the backlight side (lower side in the figure) of the liquid crystal cell 41 with the first birefringent layer 13 positioned on the liquid crystal cell 41 side. The second polarizing plate 20 is arranged on the viewing side (the upper side in the figure) of the liquid crystal cell 41 with the second birefringent layer 23 positioned on the liquid crystal cell 41 side.

  As described above, in the second liquid crystal panel, the refractive index of the first birefringent layer shows a relationship of nx = ny> nz, and the refractive index of the second birefringent layer is nx> ny ≧ It is configured to show the relationship of nz. By doing so, the contrast ratio in the front direction is significantly higher than that of a conventional liquid crystal panel (typically, the transmittance of two polarizing plates arranged on both sides of the liquid crystal cell is the same). A high liquid crystal panel can be obtained.

  The second protective layer is the same as the protective layer (the first protective layer).

  The second polarizer is the same as the polarizer (the first polarizer).

  As a material for forming the second birefringent layer, any appropriate material can be adopted as long as the refractive index shows a relationship of nx> ny ≧ nz. As the second birefringent layer, for example, a retardation film containing at least one of a norbornene resin, a polyvinyl acetal resin, a polyester resin, a polypropylene resin, a polycarbonate resin, and an acrylic resin can be used. .

First, a retardation film containing a norbornene resin will be described. The norbornene-based resin is characterized in that the absolute value of the photoelastic coefficient (C [λ], where λ can be set to, for example, 590 nm) is small. The absolute value of the photoelastic coefficient at a wavelength of 590nm of the norbornene resin (C [590]) preferably is in the range of ^{1 × 10 -12 m 2 / N~1} × 10 -11 m 2 / N. In the present invention, the “norbornene resin” refers to a (co) polymer obtained by using a norbornene monomer having a norbornene ring as a part or all of a starting material (monomer). The “(co) polymer” represents a homopolymer or a copolymer (copolymer).

As the norbornene-based resin, a norbornene-based monomer having a norbornene ring (having a double bond in the norbornane ring) is used as a starting material. In the (co) polymer state, the norbornene-based resin may or may not have a norbornane ring in the structural unit. The norbornene-based resin having a norbornane ring as a structural unit in the state of a (co) polymer is, for example, tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] Dec-3-ene, 8-methyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] dec-3-ene, 8-methoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] Dec-3-ene and the like. A norbornene-based resin that does not have a norbornane ring as a structural unit in the state of a (co) polymer is, for example, a (co) polymer obtained using a monomer that becomes a 5-membered ring by cleavage. Examples of the monomer that becomes a 5-membered ring by cleavage include norbornene, dicyclopentadiene, 5-phenylnorbornene, and derivatives thereof. When the norbornene-based resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be.

  Examples of the norbornene resin include (a) a resin obtained by hydrogenation of a ring-opening (co) polymer of a norbornene monomer, and (b) a resin obtained by addition (co) polymerization of a norbornene monomer. The hydrogenated resin of the ring-opening copolymer of the norbornene monomer is converted into a ring-opening copolymer of one or more norbornene monomers and at least one of α-olefins, cycloalkenes and non-conjugated dienes. Includes hydrogenated resins. The resin obtained by addition copolymerization of the norbornene monomer includes a resin obtained by addition copolymerization of at least one norbornene monomer and at least one of α-olefins, cycloalkenes and non-conjugated dienes.

  The resin obtained by hydrogenating the ring-opening (co) polymer of the norbornene monomer is obtained by, for example, metathesis reaction of a norbornene-based monomer to obtain a ring-opening (co) polymer, and further, the ring-opening (co) polymer. It can be obtained by hydrogenating the coalescence. Specifically, for example, the method described in paragraphs [0059] to [0060] of JP-A-11-116780, the method described in [0035] to [0037] of JP-A-2001-350017, and the like can be mentioned. It is done. The resin obtained by addition (co) polymerization of the norbornene monomer can be obtained, for example, by the method described in Example 1 of JP-A No. 61-292601.

  The weight average molecular weight (Mw) of the norbornene-based resin is preferably in the range of 20000 to 500,000, as measured by gel permeation chromatography (polystyrene standard) using a tetrahydrofuran solvent. The norbornene-based resin preferably has a glass transition temperature (Tg) in the range of 120 to 170 ° C. If it is said resin, it can have the more excellent thermal stability and can obtain the retardation film which was further excellent in the drawability. The glass transition temperature (Tg) is a value calculated by, for example, a differential scanning calorimetry (DSC) method according to JIS K7121.

  The retardation film containing the norbornene-based resin is, for example, a polymer film formed into a sheet shape by a solvent casting method or a melt extrusion method, a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, Alternatively, it is produced by stretching by a longitudinal and lateral sequential biaxial stretching method. The stretching method is preferably a lateral uniaxial stretching method from the viewpoint of production efficiency. The temperature at which the polymer film is stretched (stretching temperature) is preferably in the range of 120 to 200 ° C. The magnification (stretch ratio) for stretching the polymer film is preferably more than 1 and 4 times or less. The stretching method may be a fixed end stretching method or a free end stretching method. According to the fixed end stretching method, a retardation film showing a relationship of nx> ny> nz can be produced.

  As the retardation film containing the norbornene resin, for example, a commercially available film can be used as it is. Alternatively, a film obtained by subjecting the commercially available film to a secondary process such as at least one of a stretching process and a shrinking process can be used. Examples of the retardation film containing the commercially available norbornene resin include, for example, trade names “ARTON” series (ARTON F, ARTON FX, ARTON D) manufactured by JSR Corporation, and trade names “ZEONOR” manufactured by Optes Corporation. Series (ZEONOR ZF14, ZEONOR ZF15, ZEONOR ZF16) and the like.

  Next, a retardation film containing a polyvinyl acetal resin will be described. Although it does not specifically limit as said polyvinyl acetal resin, For example, resin containing the polymer represented by following General formula (24) described in [0026] of patent 3984277 can be used. . The polymer has excellent transparency, heat resistance, and processability by having a naphthyl group in the molecular structure.

  The polymer can be obtained, for example, by subjecting at least one of at least two aldehyde compounds and ketone compounds to a condensation reaction with a polyvinyl alcohol resin. In the polymer represented by the general formula (24), the arrangement order of the basic units of l, m, and n is not particularly limited, and may be any of alternating, random, or block. The polymer includes a polymer (so-called high polymer) having a total polymerization degree of the basic units l, m, and n of 20 or more and a large weight average molecular weight, and further includes the basic units l, m, And the total polymerization degree of n is 2 or more and less than 20, and includes low polymers (so-called oligomers) having a weight average molecular weight of about several thousand.

In the general formula (24), R ¹ and R ³ are each a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. Yes, R ¹ and R ³ may be the same or different.

In the general formula (24), R ² , A and B are each a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, and a straight chain having 1 to 4 carbon atoms. Linear or branched alkyl halide group, linear or branched alkoxy group having 1 to 4 carbon atoms, alkoxycarbonyl group, acyloxy group, amino group, azide group, nitro group, cyano group or hydroxyl group And R ² , A and B may be the same or different. However, R ² is not a hydrogen atom.

In the general formula (24), R ⁴ represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 5 to 10 carbon atoms, a substituted group. Or an unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, or a substituted or unsubstituted heterocyclic group;

In the general formula (24), R ⁵ represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a benzyl group, a silyl group, a phosphate group, an acyl group, a benzoyl group, or A sulfonyl group.

  The retardation film containing the polyvinyl acetal resin includes, for example, the polyvinyl acetal resin, compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, solvent The polymer film formed into a sheet shape by a casting method or the like is produced by stretching appropriately selecting stretching conditions (for example, stretching temperature, stretching ratio, stretching direction, etc.), stretching method, and the like.

  The retardation film used as the second birefringent layer may further contain any appropriate additive. Examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. Can be given. The content of the additive is preferably in the range of more than 0 and not more than 10 parts by weight with respect to 100 parts by weight of the main component resin.

  The refractive index of the second birefringent layer has a relationship of nx> ny ≧ nz. That is, the refractive index of the second birefringent layer may exhibit a relationship of nx> ny = nz (positive uniaxiality) or a relationship of nx> ny> nz (negative biaxiality). It is preferable to show a relationship of nx> ny = nz.

  Re [590] of the second birefringent layer is, for example, 10 nm or more, and preferably in the range of 50 to 200 nm. When the refractive index of the second birefringent layer shows a relationship of nx> ny = nz, Re [590] is, for example, in the range of 90 to 190 nm, and preferably in the range of 110 to 170 nm. When the refractive index of the second birefringent layer exhibits a relationship of nx> ny> nz (negative biaxiality), Re [590] is, for example, in the range of 70 to 170 nm, preferably 90 It is in the range of ˜150 nm.

  When the refractive index of the second birefringent layer shows a relationship of nx> ny = nz, Re [590] and Rth [590] are substantially equal. In this case, the optical compensation layer preferably satisfies the formula: | Rth (590) −Re (590) | <10 nm.

  When the refractive index of the second birefringent layer shows a relationship of nx> ny> nz, Rth [590] is larger than Re [590]. In this case, the difference between Rth [590] and Re [590] (Rth [590] −Re [590]) is, for example, in the range of 10 to 100 nm, and preferably in the range of 20 to 80 nm.

  The transmittance (T [590]) at a wavelength of 590 nm of the second birefringent layer is preferably 90% or more.

  The second birefringent layer may be a single layer or a laminate composed of a plurality of layers. The thickness of the second birefringent layer is, for example, in the range of 0.5 to 200 μm.

  The liquid crystal cell is the same as the liquid crystal cell in the first liquid crystal panel.

  It is preferable that the first polarizing plate and the second polarizing plate are arranged so that their absorption axes are orthogonal to each other. The thickness of the second polarizing plate is the same as that of the polarizing plate of the present invention (first polarizing plate).

The degree of polarization of at least one of the first polarizing plate and the second polarizing plate is preferably 99% or more. By setting the degree of polarization to 99% or more, a liquid crystal panel with a higher contrast ratio in the front direction can be obtained. The degree of polarization is more preferably 99.5% or more, and further preferably 99.8% or more. The degree of polarization can be measured using, for example, a spectrophotometer (trade name “DOT-3” manufactured by Murakami Color Research Laboratory Co., Ltd., product name “V-7100” manufactured by JASCO Corporation), and the like. . As a specific method for measuring the degree of polarization, parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the first polarizing plate and the second polarizing plate are measured, and the formula: degree of polarization ( %) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100. The parallel transmittance (H ₀ ) is a transmittance value of a parallel laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminated polarizing plate prepared by superposing two identical polarizing plates so that their absorption axes are orthogonal to each other. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2nd visual field (C light source) of JISZ8701 (1982 edition).

  The liquid crystal display device of the present invention includes the polarizing plate or the liquid crystal panel of the present invention. An example of the configuration of the liquid crystal display device of the present invention is shown in the schematic sectional view of FIG. In the figure, the size, ratio, and the like of each component are different from actual ones for easy understanding. As illustrated, the liquid crystal display device 200 includes at least a liquid crystal panel 100 and a direct-type backlight unit 80 disposed on one side of the liquid crystal panel 100. The direct-type backlight unit 80 includes at least a light source 81, a reflection film 82, a diffusion plate 83, a prism sheet 84, and a brightness enhancement film 85. In the liquid crystal display device 200 of this example, the case where the direct type is adopted as the backlight unit is shown, but the present invention is not limited to this, and is, for example, a sidelight type backlight unit. May be. The sidelight type backlight unit further includes at least a light guide plate and a light reflector in addition to the configuration of the direct type. In addition, as long as the effects of the present invention are obtained, some of the components illustrated in FIG. 5 can be omitted depending on the application, such as the illumination method of the liquid crystal display device and the drive mode of the liquid crystal cell, or Other optical members can be substituted.

  The liquid crystal display device of the present invention may be a transmissive type in which light is irradiated from the backlight side of the liquid crystal panel and the screen is viewed, or a reflective type in which light is irradiated from the viewing side of the liquid crystal panel and the screen is viewed. Alternatively, it may be a transflective type having both transmissive and reflective properties.

  The liquid crystal display device of the present invention is used for any appropriate application. Applications include, for example, OA devices such as personal computer monitors, laptop computers, and copy machines, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as portable game machines, video cameras, televisions, microwave ovens, etc. Household electrical equipment, back monitor, car navigation system monitor, car audio and other in-vehicle equipment, display equipment for commercial store information monitors, security equipment such as monitoring monitors, nursing care monitors, medical monitors, etc. Nursing care / medical equipment.

  A preferred application of the liquid crystal display device of the present invention is a television. The screen size of the television is preferably a wide 17 type (373 mm × 224 mm) or more, more preferably a wide 23 type (499 mm × 300 mm) or more, and further preferably a wide 32 type (687 mm × 412 mm). That's it.

  Next, examples of the present invention will be described together with comparative examples. However, the present invention is not limited at all by the following examples and comparative examples. Various physical properties in each example and each comparative example were measured by the following methods.

(In-plane retardation Re [550] at a wavelength of 550 nm, thickness direction retardation Rth [550], Δn and Nz coefficient)
The in-plane retardation Re [550], thickness direction retardation Rth [550], Δn, and Nz coefficient at a wavelength of 550 nm were measured using a product name “KOBRA-21ADH” manufactured by Oji Scientific Instruments.

(Thickness)
When the thickness was less than 10 μm, the measurement was performed using a thin film spectrophotometer (trade name “instant multiphotometry system MCPD-2000” manufactured by Otsuka Electronics Co., Ltd.). When the thickness was 10 μm or more, measurement was performed using a digital micrometer “KC-351C type” manufactured by Anritsu.

[Example 1]
2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl were used as starting materials, and polyimide was prepared according to a conventional method. Prepared. The obtained polyimide was dissolved in cyclohexanone to prepare a 15 wt% polyimide solution. On the other hand, a triacetyl cellulose (TAC) film (manufactured by FUJIFILM Corporation, trade name “TD-80UL”, thickness: 80 μm, width 1490 mm) is stretched 1.05 times at 170 ° C. by lateral stretching at a fixed end. Then, a stretched TAC film having a thickness of 76 μm was produced. Then, the polyimide solution was applied on the stretched TAC film with a thickness of about 30 μm. Subsequently, the laminated body by which the polyimide layer about 3 micrometers thick was laminated | stacked on the said extending | stretched TAC film by performing the drying process for 3 minutes at 120 degreeC. This optical film was an optical film having optical characteristics satisfying the relationship of nx = ny> nz.

[Example 2]
In the stretching, an optical film was produced in the same manner as in Example 1 except that the stretching treatment was performed at a stretching ratio of 1.10. At this time, the stretched TAC film had a thickness of 73 μm.

[Example 3]
In the stretching, an optical film was produced in the same manner as in Example 1 except that the stretching treatment was performed at a stretching ratio of 1.15. At this time, the thickness of the stretched TAC film was 70 μm.

[Example 4]
An optical film was produced in the same manner as in Example 1 except that the stretching was performed at a stretching ratio of 1.20. At this time, the stretched TAC film had a thickness of 67 μm.

[Comparative Example 1]
An optical film was produced in the same manner as in Example 1 except that the stretching treatment was not performed.

[Comparative Example 2]
An optical film was produced in the same manner as in Example 1 except that the stretching was performed at a stretching ratio of 1.30. At this time, the thickness of the stretched TAC film was 62 μm.

[Evaluation]
(Degree of polarization)
After the polyvinyl alcohol film was dyed in an aqueous solution containing iodine, it was uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to produce a polarizer. One side of the polarizer was attached to the stretched TAC film side of the optical films produced in Examples 1 to 4 and Comparative Examples 1 and 2 via a polyvinyl alcohol-based adhesive (thickness: 0.1 μm). Furthermore, a TAC film (thickness: 80 μm) was similarly attached to the other side of the polarizer to produce a laminated polarizing plate. The polarization degree of this laminated polarizing plate was measured using an ultraviolet-visible spectrophotometer (trade name “V-7100” manufactured by JASCO Corporation). The degree of polarization was measured at nine points of 0 mm, 100 mm, 200 mm, 350 mm, 730 mm, 1110 mm, 1260 mm, 1360 mm, and 1460 mm from the end in the width direction of the optical film. The measurement results are shown in FIGS. 6 to 11, and the variation in the degree of polarization (standard deviation of the measured values) is shown in Table 1. Start in the figure is a measurement result at the beginning of winding of the original film of the optical film, and End in the figure is a measurement result at the end of winding of the original film of the optical film.

(Orientation axis angle)
The orientation axis angles of the optical films produced in Examples 1 to 4 and Comparative Examples 1 to 2 were measured using “Axo Scan” manufactured by Axo Metrics. The orientation axis angle was measured at 15 points at a pitch of about 100 mm in the width direction of the optical film. The measurement results are shown in FIG. 12 to FIG. The orientation axis of the original film was 0 ° in the TD direction and 90 ° in the MD direction.

(Haze)
The hazes of the optical films produced in Examples 1 to 4 and Comparative Examples 1 to 2 were measured using a haze / transmittance meter (trade name “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd.). The measurement results are shown in Table 1.

(contrast)
After the polyvinyl alcohol film was dyed in an aqueous solution containing iodine, it was uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to produce a polarizer. One side of the polarizer was attached to the stretched TAC film side of the optical films produced in Examples 1 to 4 and Comparative Examples 1 and 2 via a polyvinyl alcohol-based adhesive (thickness: 0.1 μm). Furthermore, a TAC film (thickness: 80 μm) was similarly attached to the other side of the polarizer to produce a laminated polarizing plate. Next, this laminated polarizing plate was mounted on the backlight side of a liquid crystal cell taken out from a liquid crystal television (S-2500) manufactured by SONY. Further, a birefringent layer (manufactured by JSR Corporation, “ARTON”) having Δnd = 110 nm and Nz coefficient ((nx−nz) / (nx−ny)) = 1.3 is provided on the viewing side of the liquid crystal panel. A birefringent layer-integrated laminated polarizing plate (manufactured by Nitto Denko Corporation, trade name: “NXAEFCVEQAGAU 01”) having a liquid crystal display device was prepared. The contrast characteristics of the liquid crystal display device were measured using a color luminance meter (trade name “BM-5” manufactured by Topcon Technohouse Co., Ltd.) after being left for 1 hour or longer after the backlight was turned on. The measurement results are shown in Table 1.

  In Examples 1 to 4, an optical film having a small variation in the orientation axis angle and a small haze was obtained, and the obtained optical film had a small variation in the degree of polarization when laminated on a polarizing plate, and was attached to a liquid crystal cell. The contrast characteristics were also good. On the other hand, in Comparative Examples 1 and 2, the variation in the degree of polarization was large, and desired optical characteristics could not be obtained. In Comparative Example 2, the orientation axis angle could not be measured because of high haze.

  By the method for producing an optical film of the present invention, it is possible to obtain an optical film capable of improving the variation in the degree of polarization particularly in the original fabric width direction and obtaining excellent contrast characteristics when used in a liquid crystal panel. Applications of the obtained optical film, polarizing plate including the optical film, liquid crystal panel, and liquid crystal display device using the same include, for example, OA equipment such as desktop personal computers, notebook personal computers, copiers, mobile phones, watches, digital cameras , Portable devices such as personal digital assistants (PDAs), portable game machines, household electrical devices such as video cameras, televisions, and microwave ovens, back monitors, monitors for car navigation systems, in-vehicle devices such as car audio, for commercial stores Display equipment such as information monitors, security equipment such as monitoring monitors, nursing care and medical equipment such as nursing monitors and medical monitors, and the like are not limited and can be applied to a wide range of fields.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the polarizing plate of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the first liquid crystal panel of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of the configuration of the second liquid crystal panel of the present invention. FIG. 4 is a schematic cross-sectional view showing an example of the configuration of the liquid crystal cell provided in the liquid crystal panel of the present invention. FIG. 5 is a schematic cross-sectional view showing an example of the configuration of the liquid crystal display device of the present invention. 6 is a graph showing the result of measuring the degree of polarization of a polarizing plate using the optical film obtained in Example 1. FIG. FIG. 7 is a graph showing the result of measuring the degree of polarization of a polarizing plate using the optical film obtained in Example 2. FIG. 8 is a graph showing the results of measuring the degree of polarization of a polarizing plate using the optical film obtained in Example 3. FIG. 9 is a graph showing the result of measuring the degree of polarization of a polarizing plate using the optical film obtained in Example 4. FIG. 10 is a graph showing the results of measuring the degree of polarization of a polarizing plate using the optical film obtained in Comparative Example 1. FIG. 11 is a graph showing the result of measuring the degree of polarization of a polarizing plate using the optical film obtained in Comparative Example 2. FIG. 12 is a graph showing the result of measuring the orientation axis angle of the optical film obtained in Example 1. FIG. 13 is a graph showing the result of measuring the orientation axis angle of the optical film obtained in Example 2. FIG. 14 is a graph showing the result of measuring the orientation axis angle of the optical film obtained in Example 3. FIG. 15 is a graph showing the results of measuring the orientation axis angle of the optical film obtained in Example 4. FIG. 16 is a graph showing the result of measuring the orientation axis angle of the optical film obtained in Comparative Example 1.

Explanation of symbols

10 Polarizing plate (first polarizing plate)
11 Protective layer (first protective layer)
12 Polarizer (first polarizer)
13 Optical film (first birefringent layer)
20 second polarizing plate 21 second protective layer 22 second polarizer 23 second birefringent layers 30, 40, 100 liquid crystal panel 41 liquid crystal cell 411a, 411b substrate 412 spacer 413 liquid crystal layer 80 backlight unit 81 light source 82 Reflective film 83 Diffusion plate 84 Prism sheet 85 Brightness enhancement film 200 Liquid crystal display device

Claims (10)

A method for producing an optical film comprising a transparent film and a birefringent layer, wherein the birefringent layer has a refractive index distribution of nx = ny> nz, wherein the transparent film is 1.05 to 1.25 in the width direction. A method for producing an optical film, comprising: a step of homogenizing an orientation axis that is stretched at a stretch ratio in the range of twice; and a step of forming a birefringent layer on the stretched transparent film.
(Nx, ny, and nz represent the refractive indexes of the X-axis, Y-axis, and Z-axis in the birefringent layer, respectively, and the X-axis represents the maximum refractive index in the plane of the birefringent layer. The Y axis is an axial direction perpendicular to the X axis in the plane, and the Z axis is a thickness direction perpendicular to the X axis and the Y axis.) The method for producing an optical film according to claim 1, wherein the step of forming the birefringent layer is a step of applying a material containing a non-liquid crystalline material. The method for producing an optical film according to claim 2, wherein the non-liquid crystalline material is at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. The manufacturing method of the optical film as described in any one of Claim 1 to 3 whose said transparent film is a triacetyl cellulose. The manufacturing method of the optical film as described in any one of Claims 1-4 whose extending | stretching temperature of the transparent film in the homogenization process of the said orientation axis is the range of 120-200 degreeC. An optical film comprising a transparent film and a birefringent layer, wherein the optical film is produced by the method for producing an optical film according to any one of claims 1 to 5. A polarizing plate comprising an optical film and a polarizer, wherein the optical film is the optical film according to claim 6. A liquid crystal panel including a liquid crystal cell and an optical member,
The optical member is the optical film according to claim 6 or the polarizing plate according to claim 7,
The liquid crystal panel, wherein the optical member is disposed on at least one side of the liquid crystal cell. A first polarizing plate, a second polarizing plate, and a liquid crystal cell, wherein the first polarizing plate is disposed on a backlight side of the liquid crystal cell, and the second polarizing plate is visible to the liquid crystal cell. A liquid crystal panel arranged on the side,
The first polarizing plate includes a first polarizer and a first birefringent layer,
The first birefringent layer is disposed between the first polarizer and the liquid crystal cell,
The refractive index of the first birefringent layer has a relationship of nx = ny> nz,
The second polarizing plate includes a second polarizer and a second birefringent layer,
The second birefringent layer is disposed between the second polarizer and the liquid crystal cell,
In the liquid crystal panel showing a relationship of nx> ny ≧ nz, the refractive index of the second birefringent layer is as follows:
The liquid crystal panel, wherein the first polarizing plate is the polarizing plate according to claim 7, and the optical film contained in the polarizing plate according to claim 7 is the first birefringent layer. . A liquid crystal display device comprising an optical member or a liquid crystal panel, wherein the optical member is an optical film according to claim 6 or a polarizing plate according to claim 7, and the liquid crystal panel is a liquid crystal according to claim 8 or 9. A liquid crystal display device that is a panel.

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