JP5273775B2 - Laminated optical film, liquid crystal panel and liquid crystal display device using laminated optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer optical film which is excellent in a screen contrast and is less in color shift, and to provide a liquid crystal panel and a liquid crystal display device. <P>SOLUTION: The multilayer optical film comprises a polarizer, a first optical compensation layer having an index ellipsoid showing a relationship of nx&gt;ny=nz, and a second optical compensation layer having an index ellipsoid showing a relationship of nz&gt;nx&gt;ny, wherein the polarizer and compensation layers are placed in such a manner that an absorption axis of the polarizer and a slow axis of the first optical compensation layer are parallel to or orthogonal to each other and that an absorption axis of the polarizer and a slow axis of the second optical compensation layer are parallel to or orthogonal to each other. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a laminated optical film, a liquid crystal panel using the laminated optical film, and a liquid crystal display device. More specifically, the present invention relates to a laminated optical film having a polarizer and two optical compensation layers, a liquid crystal panel using the laminated optical film, and a liquid crystal display device.

  In general, various optical films in which a polarizing film and an optical compensation layer are combined are used in image display devices (for example, liquid crystal display devices) in order to perform optical compensation.

  A circularly polarizing plate which is a kind of the optical film can be usually produced by combining a polarizing film and a λ / 4 plate. However, the λ / 4 plate generally exhibits a characteristic that the phase difference value increases as the wavelength becomes shorter, that is, a so-called “positive wavelength dispersion characteristic”, and generally has a large wavelength dispersion characteristic. Therefore, there is a problem that desired optical characteristics (for example, a function as a λ / 4 plate) cannot be exhibited over a wide wavelength range. In order to avoid such problems, in recent years, as a phase difference plate exhibiting a wavelength dispersion characteristic in which a retardation value increases as the wavelength becomes longer, that is, a so-called “reverse dispersion characteristic”, for example, a modified cellulose film and Modified polycarbonate films have been proposed. However, these films have a problem in terms of cost.

Therefore, at present, for a λ / 4 plate having positive wavelength dispersion characteristics, for example, by combining a retardation plate whose retardation value increases as it becomes longer wavelength side, or a λ / 2 plate, the above-mentioned λ / 4 plate is used. A method of correcting the wavelength dispersion characteristics of the plate is employed (see, for example, Patent Document 1). However, these techniques are insufficient in both improving the screen contrast and reducing the color shift.
Japanese Patent No. 3174367

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a laminated optical film, a liquid crystal panel, and a liquid crystal display device that have excellent screen contrast and a small color shift. is there.

  The laminated optical film of the present invention includes a polarizer, a first optical compensation layer in which a refractive index ellipsoid has a relationship of nx> ny = nz, and a second in which a refractive index ellipsoid has a relationship of nz> nx> ny. The optical axis of the polarizer is arranged so that the absorption axis of the polarizer and the slow axis of the first optical compensation layer are parallel or orthogonal, and the absorption axis of the polarizer and the second optical compensation It arrange | positions so that the slow axis of a layer may be parallel or orthogonal.

  In a preferred embodiment, the Nz coefficient of the second optical compensation layer is −1.0 or less.

In a preferred embodiment, the in-plane retardation Re _{2 of} the second optical compensation layer satisfies a relationship of 0 nm <Re ₂ ≦ 70 nm.

  In a preferred embodiment, the refractive index ellipsoid further includes a third optical compensation layer exhibiting a relationship of nx> ny = nz or nx> ny> nz.

In a preferred embodiment, the in-plane retardation Re _{3 of} the third optical compensation layer is 80 to 200 nm.

  In a preferred embodiment, the refractive index ellipsoid further includes a fourth optical compensation layer exhibiting a relationship of nx = ny> nz.

  According to another aspect of the present invention, a liquid crystal panel is provided. The liquid crystal panel includes a liquid crystal cell and the laminated optical film.

  In a preferred embodiment, the liquid crystal cell is a VA mode.

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

  According to the present invention, by arranging the first optical compensation layer and the second optical compensation layer having the above optical characteristics at a predetermined angle, the screen contrast can be improved and the color shift can be reduced. .

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
The in-plane retardation (Re) means an in-plane retardation value of a layer (film) at 23 ° C., and a wavelength of 590 nm unless otherwise specified. Re is obtained by Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). In this specification, when Re (550) is indicated, it means an in-plane retardation of a layer (film) at a wavelength of 550 nm. Also, the subscript “1” attached to the terms and symbols described in this specification represents the first optical compensation layer, and the subscript “2” represents the second optical compensation layer. For example, showing an in-plane retardation of the first optical compensation layer and the Re _1.
(3) Thickness direction retardation (Rth)
Thickness direction retardation (Rth) is a retardation value in the thickness direction of a layer (film) at a wavelength of 590 nm unless otherwise specified. Rth is determined by Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film). In addition, in this specification, when Rth (550) is shown, it means the retardation in the thickness direction of the layer (film) at a wavelength of 550 nm. In the present specification, for example, the thickness direction retardation of the first optical compensation layer is indicated as Rth ₁ .
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) λ / 4 plate The λ / 4 plate is an electro-optic birefringent plate having a function of generating a quarter-wavelength optical path difference between linearly polarized light vibrating in directions perpendicular to each other. Say.

A. Laminated optical film A-1. 1 is a schematic cross-sectional view of a laminated optical film according to a preferred embodiment of the present invention. The laminated optical film 10 includes a polarizer 11, a first optical compensation layer 12, and a second optical compensation layer 13. The first optical compensation layer 12 and the second optical compensation layer 13 are disposed on one side of the polarizer 11. FIG. 1B is a schematic cross-sectional view of a laminated optical film according to another preferred embodiment of the present invention. This laminated optical film 10 ′ includes a polarizer 11, a first optical compensation layer 12, a second optical compensation layer 13, a third optical compensation layer 14, and a fourth optical compensation disposed on one side of the polarizer 11. A compensation layer 15 is provided. The order in which the optical compensation layers are stacked is not particularly limited, and any appropriate order can be adopted. Preferably, as in the illustrated example, the polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, and the fourth optical compensation layer are laminated in this order.

  Although not shown in FIGS. 1A and 1B, the laminated optical film of the present invention includes a first protective layer between the polarizer 11 and the optical compensation layer as necessary. A second protective layer is provided on the side where the optical compensation layer is not disposed. Moreover, the laminated optical film of this invention is further equipped with arbitrary appropriate optical compensation layers as needed.

  The first optical compensation layer 12 has a refractive index ellipsoid of nx> ny = nz. The first optical compensation layer 12 is arranged so that its slow axis forms any appropriate angle with respect to the absorption axis of the polarizer 11 according to the purpose, the configuration of the applied liquid crystal panel, and the like. Preferably, the polarizer 11 and the first optical compensation layer 12 are arranged so that the absorption axis and the slow axis thereof are parallel or orthogonal to each other. More preferably, the polarizer and the first optical compensation layer are arranged so that the absorption axis and the slow axis thereof are orthogonal to each other. By disposing the polarizer 11 and the first optical compensation layer 12 in such a positional relationship, a liquid crystal panel with improved screen contrast and reduced color shift can be obtained. In the present specification, the term “parallel” includes the case of being substantially parallel. Here, “substantially parallel” includes the case of 0 ° ± 3.0 °, preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. In the present specification, the term “orthogonal” includes a case of being substantially orthogonal. Here, “substantially orthogonal” includes the case of 90 ° ± 3.0 °, preferably 90 ° ± 1.0 °, more preferably 90 ° ± 0.5 °.

  The second optical compensation layer 13 has a refractive index ellipsoid of nz> nx> ny. The second optical compensation layer 13 is arranged so that its slow axis forms any appropriate angle with respect to the absorption axis of the polarizer 11 according to the purpose, the configuration of the liquid crystal panel, and the like. Preferably, the polarizer 11 and the second optical compensation layer 13 are disposed so that the absorption axis and the slow axis thereof are parallel or orthogonal to each other. More preferably, the polarizer and the second optical compensation layer are arranged so that the absorption axis and the slow axis thereof are orthogonal to each other. By disposing the polarizer 11 and the second optical compensation layer 13 in such a positional relationship, a liquid crystal panel with improved screen contrast and reduced color shift can be obtained.

  The third optical compensation layer 14 has a refractive index ellipsoid of nx> ny = nz or nx> ny> nz. The third optical compensation layer 14 is arranged so that its slow axis forms any appropriate angle with respect to the absorption axis of the polarizer 11 according to the purpose, the configuration of the liquid crystal panel, and the like. Specifically, the third optical compensation layer 14 has a slow axis of preferably 30 ° to 60 °, more preferably 35 ° to 55 °, and still more preferably 40 ° with respect to the absorption axis of the polarizer 11. It is arranged so as to form an angle of ˜50 °, particularly preferably 43 to 47 °, and most preferably about 45 °. By disposing the polarizer 11 and the second optical compensation layer 13 in such a positional relationship, a liquid crystal panel with improved screen contrast and reduced color shift can be obtained.

  The total thickness of the laminated optical film of the present invention is preferably 100 to 400 μm, more preferably 150 to 300 μm, and particularly preferably 180 to 250 μm. Hereinafter, the detail of each layer which comprises the laminated optical film of this invention is demonstrated.

A-2. First Optical Compensation Layer The first optical compensation layer has a refractive index ellipsoid having a relationship of nx> ny = nz. Here, “ny = nz” includes not only the case where ny and nz are exactly equal, but also the case where ny and nz are substantially equal. Specifically, it means that the Nz coefficient (Rth ₁ / Re ₁ ) is more than 0.9 and less than 1.1. The in-plane retardation Re ₁ of the first optical compensation layer is preferably 80 to 200 nm, more preferably 80 to 150 nm, and still more preferably 80 to 120 nm. By providing the first optical compensation layer having such optical characteristics, the absorption axis of the polarizer can be suitably compensated, and the screen contrast of the liquid crystal panel can be improved. Further, the color shift can be reduced.

  As a material for forming the first optical compensation layer, any appropriate material can be adopted as long as the above characteristics are obtained. A liquid crystal material is preferable, and a liquid crystal material (nematic liquid crystal) in which the liquid crystal phase is a nematic phase is more preferable. By using the liquid crystal material, the difference between nx and ny of the obtained optical compensation layer can be significantly increased as compared with the non-liquid crystal material. As a result, the thickness of the optical compensation layer for obtaining a desired in-plane retardation can be remarkably reduced, and the resulting laminated optical film and liquid crystal panel can be made thinner. As such a liquid crystal material, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystal material may exhibit a liquid crystallinity mechanism either lyotropic or thermotropic. The alignment state of the liquid crystal is preferably homogeneous alignment. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

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

  Specific examples of the method for forming the liquid crystal monomer and the first optical compensation layer include monomers and methods described in JP-A-2006-178389.

  The thickness of the first optical compensation layer can be set so that desired optical characteristics can be obtained. When the first optical compensation layer is formed of a liquid crystal material, the thickness is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and still more preferably 0.5 to 5 μm.

  The first optical compensation layer can also be formed by stretching a polymer film. Specifically, by appropriately selecting the type of polymer, stretching conditions (for example, stretching temperature, stretching ratio, stretching direction), stretching method, etc., the desired optical characteristics (for example, refractive index ellipsoid, in-plane The first optical compensation layer having a retardation and a retardation in the thickness direction can be obtained. More specifically, the stretching temperature is preferably 110 to 170 ° C, more preferably 130 to 150 ° C. The draw ratio is preferably 1.37 to 1.67 times, more preferably 1.42 to 1.62 times. Examples of the stretching method include lateral uniaxial stretching.

  When the first optical compensation layer is formed by stretching a polymer film, the thickness is preferably 5 to 55 μm, more preferably 10 to 50 μm, and still more preferably 15 to 45 μm.

  Arbitrary appropriate resin may be employ | adopted as resin which forms the said polymer film. Specific examples include resins constituting a positive birefringent film such as norbornene resin, polycarbonate resin, cellulose resin, polyvinyl alcohol resin, and polysulfone resin. Of these, norbornene resins and polycarbonate resins are preferable.

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

  As the polycarbonate resin, an aromatic polycarbonate is preferably used. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable. Specific examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxyphenyl). ) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2, 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl And cyclohexane. You may use these individually or in combination of 2 or more types. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are Used. In particular, it is preferable to use both 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

A-3. Second Optical Compensation Layer In the second optical compensation layer, the refractive index ellipsoid has a relationship of nz>nx> ny. Such a layer (film) exhibiting a refractive index ellipsoid may be referred to as a “positive biaxial plate” or a “positive biaxial plate”.

The in-plane retardation Re ₂ of the second optical compensation layer preferably satisfies the relationship 0 nm <Re ₂ ≦ 70 nm. Re ₂ more preferably satisfies the relationship of 0 nm <Re ₂ ≦ 60 nm, more preferably 0 nm <Re ₂ ≦ 50 nm, and particularly preferably 10 nm <Re ₂ <50 nm. The thickness direction retardation Rth ₂ of the second optical compensation layer is preferably −200 to −50 nm, more preferably −100 to −50 nm, and particularly preferably −80 to −60 nm. The Nz coefficient (Rth ₂ / Re ₂ ) of the second optical compensation layer is preferably −1.0 or less, more preferably −10 to −1.0, and particularly preferably −8.0 to −1. 6. By providing the second optical compensation layer having such optical characteristics, the absorption axis of the polarizer can be suitably compensated, and the screen contrast of the liquid crystal panel can be improved. Further, the color shift can be reduced.

  The second optical compensation layer can be of any suitable configuration. Specifically, the retardation film alone may be used, or a laminate of two or more retardation films that are the same or different may be used. In the case of a laminate, the second optical compensation layer may include a pressure-sensitive adhesive layer or an adhesive layer for attaching two or more retardation films. Preferably, the second optical compensation layer is a single retardation film. By adopting such a configuration, it is possible to reduce the shift and unevenness of the retardation value due to the contraction stress of the polarizer and the heat of the light source, and to contribute to the thinning of the obtained liquid crystal panel.

  The optical characteristics of the retardation film can be set to any appropriate value depending on the configuration of the second optical compensation layer. For example, when the second optical compensation layer is a retardation film alone, it is preferable that the optical characteristics of the retardation film be equal to the optical characteristics of the second optical compensation layer. Therefore, it is preferable that the retardation values of the pressure-sensitive adhesive layer, the adhesive layer, and the like used when laminating the retardation film on a polarizer or other optical compensation layer are as small as possible.

  The total thickness of the second optical compensation layer is preferably 10 to 500 μm, more preferably 20 to 400 μm, and particularly preferably 30 to 300 μm. When the thickness of the second optical compensation layer is within such a range, the handling property at the time of manufacture is excellent, and the optical uniformity of the obtained liquid crystal display device (liquid crystal panel) can be enhanced.

  As the retardation film, a film which is excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like and hardly causes optical unevenness due to strain is preferably used. As the retardation film, a stretched polymer film mainly composed of a thermoplastic resin is preferably used. As the thermoplastic resin, a polymer exhibiting negative birefringence is preferably used. By using a polymer exhibiting negative birefringence, a retardation film having a refractive index ellipsoid of nz> nx> ny can be easily obtained. Here, “showing negative birefringence” means that when the polymer is oriented by stretching or the like, the refractive index in the stretching direction becomes relatively small. In other words, the refractive index in the direction orthogonal to the stretching direction is increased. Examples of the polymer exhibiting negative birefringence include a polymer in which a chemical bond or a functional group having a large polarization anisotropy such as an aromatic ring or a carbonyl group is introduced into a side chain. Specific examples include acrylic resins, styrene resins, maleimide resins, and the like.

  The acrylic resin can be obtained, for example, by addition polymerization of an acrylate monomer. Examples of the acrylic resin include polymethyl methacrylate (PMMA), polybutyl methacrylate, polycyclohexyl methacrylate, and the like.

  The styrene resin can be obtained, for example, by addition polymerization of a styrene monomer. Examples of the styrenic monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, 2,5-dichlorostyrene, pt-butylstyrene, etc. are mentioned.

  The maleimide resin can be obtained, for example, by addition polymerization of a maleimide monomer. Examples of maleimide monomers include N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, and N- (2-propylphenyl). ) Maleimide, N- (2-isopropylphenyl) maleimide, N- (2,6-dimethylphenyl) maleimide, N- (2,6-dipropylphenyl) maleimide, N- (2,6-diisopropylphenyl) maleimide, N- (2-methyl-6-ethylphenyl) maleimide, N- (2-chlorophenyl) maleimide, N- (2,6-dichlorophenyl) maleimide, N- (2-bromophenyl) maleimide, N- (2,6 -Dibromophenyl) maleimide, N- (2-biphenyl) maleimide, N- 2-cyanophenyl) maleimide, and the like. The maleimide monomer can be obtained from, for example, Tokyo Chemical Industry Co., Ltd.

  In the above addition polymerization, the birefringence characteristics of the obtained resin can be controlled by, for example, substituting the side chain, allowing the maleimidation or grafting reaction after the polymerization.

  The polymer exhibiting negative birefringence may be copolymerized with other monomers. When other monomers are copolymerized, brittleness, molding processability, and heat resistance can be improved. Examples of the other monomer include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, and 1-hexene; acrylonitrile; acrylic acid (Meth) acrylates such as methyl and methyl methacrylate; maleic anhydride; vinyl esters such as vinyl acetate and the like.

  When the polymer exhibiting negative birefringence is a copolymer of the styrene monomer and the other monomer, the blending ratio of the styrene monomer is preferably 50 to 80 mol%. When the polymer exhibiting negative birefringence is a copolymer of the maleimide monomer and the other monomer, the blending ratio of the maleimide monomer is preferably 2 to 50 mol%. By blending in such a range, a polymer film excellent in toughness and molding processability can be obtained.

  As the polymer exhibiting negative birefringence, a styrene-maleic anhydride copolymer, a styrene-acrylonitrile copolymer, a styrene- (meth) acrylate copolymer, a styrene-maleimide copolymer, a vinyl ester- A maleimide copolymer, an olefin-maleimide copolymer, or the like is used. These can be used alone or in combination of two or more. These polymers exhibit high negative birefringence and can be excellent in heat resistance. These polymers can be obtained from Nova Chemical Japan, Arakawa Chemical Industries, Ltd., etc., for example.

As the polymer exhibiting negative birefringence, a polymer having a repeating unit represented by the following general formula (I) is also preferably used. Such a polymer can further exhibit high negative birefringence and can be excellent in heat resistance and mechanical strength. Such a polymer can be obtained, for example, by using N-phenyl-substituted maleimide having a phenyl group having a substituent at least in the ortho position as the N-substituent of the starting maleimide monomer.

In the general formula (I), R _{1 to} R ₅ are each independently hydrogen, a halogen atom, a carboxylic acid, a carboxylic acid ester, a hydroxyl group, a nitro group, or a linear or branched group having 1 to 8 carbon atoms. Represents an alkyl group or an alkoxy group (provided that R ₁ and R ₅ are not hydrogen atoms at the same time), and R ₆ and R ₇ represent hydrogen or a linear or branched alkyl group or alkoxy group having 1 to 8 carbon atoms. N represents an integer of 2 or more.

  The polymer exhibiting negative birefringence is not limited to the above, and for example, a cyclic olefin copolymer as disclosed in JP-A-2005-350544 and the like can also be used. Furthermore, a composition containing a polymer and inorganic fine particles as disclosed in JP-A-2005-156862, JP-A-2005-227427, and the like can also be suitably used. Moreover, as a polymer which shows negative birefringence, 1 type may be used independently and 2 or more types may be mixed and used. Further, they can be used after being modified by copolymerization, branching, crosslinking, molecular end modification (or sealing), stereoregular modification, or the like.

  The polymer film may further contain any appropriate additive as required. Specific examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, thickeners, etc. Is mentioned. The kind and content of the additive can be appropriately set according to the purpose. The content of the additive is typically about 3 to 10 parts by weight with respect to 100 parts by weight of the total solid content of the polymer film. If the content of the additive is excessively large, the transparency of the polymer film may be impaired, or the additive may ooze from the surface of the polymer film.

  Any appropriate forming method can be adopted as a method for forming the polymer film. Examples thereof include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, solvent casting, and the like. Among these, the extrusion molding method and the solvent casting method are preferably used. This is because a retardation film having high smoothness and good optical uniformity can be obtained. Specifically, in the extrusion molding method, the resin composition containing the thermoplastic resin, plasticizer, additive and the like is heated and melted, and this is extruded into a thin film shape on the surface of the casting roll by a T die or the like. It is a method of forming a film by cooling. In the solvent casting method, a concentrated solution (dope) in which the resin composition is dissolved in a solvent is defoamed and cast uniformly on a surface of a metallic endless belt or rotating drum, or a plastic substrate in the form of a thin film. The film is formed by evaporating the solvent. The molding conditions can be appropriately set according to the composition and type of the resin used, the molding method, and the like.

  The retardation film (stretched film) can be obtained by stretching the polymer film under any appropriate stretching condition. Specific examples of the stretching method include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method. Preferably, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method are used. This is because a biaxial retardation film can be suitably obtained. In the polymer exhibiting negative birefringence, since the refractive index in the stretching direction is relatively small as described above, the transverse uniaxial stretching method has a slow axis in the transport direction of the polymer film ( The refractive index in the transport direction is nx). In the case of the longitudinal / horizontal sequential biaxial stretching method and the longitudinal / horizontal simultaneous biaxial stretching method, both the conveying direction and the width direction can be slow axes depending on the ratio of the longitudinal and lateral stretching ratios. Specifically, when the stretching ratio in the longitudinal (conveyance) direction is relatively large, the transverse (width) direction becomes the slow axis, and when the stretching ratio in the transverse (width) direction is relatively large, the longitudinal (conveyance) The direction is the slow axis.

  Any appropriate stretching apparatus can be used as the stretching apparatus used for the stretching. Specific examples include a roll stretching machine, a tenter stretching machine, a pantograph type or a linear motor type biaxial stretching machine. When stretching while heating, the temperature may be continuously changed or may be changed stepwise. Further, the stretching process may be divided into two or more times.

  The stretching temperature (temperature in the stretching oven when stretching the polymer film) is preferably near the glass transition temperature (Tg) of the polymer film. Specifically, it is preferably (Tg-10) ° C to (Tg + 30) ° C, more preferably Tg to (Tg + 25) ° C, and particularly preferably (Tg + 5) ° C to (Tg + 20) ° C. If the stretching temperature is too low, the retardation value and the direction of the slow axis may be non-uniform, or the polymer film may be crystallized (white turbidity). On the other hand, if the stretching temperature is excessively high, the polymer film may be melted or the retardation may be insufficiently developed. The stretching temperature is typically 110 to 200 ° C. In addition, a glass transition temperature can be calculated | required by DSC method according to JISK7121-1987.

  Arbitrary appropriate methods may be employ | adopted for the method of controlling the temperature in the said drawing oven. Examples thereof include a method using an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll, or a metal belt.

  The draw ratio when stretching the polymer film is set to any appropriate value depending on the composition of the polymer film, the type of volatile component, the residual amount of volatile component, the desired retardation value, etc. Can be done. Preferably it is 1.05-5.00 times. Moreover, the feeding speed at the time of stretching is preferably 0.5 to 20 m / min from the viewpoint of mechanical accuracy and stability of the stretching apparatus.

  As mentioned above, although the method of obtaining a retardation film using the polymer which shows negative birefringence has been described, the retardation film can also be obtained using the polymer which shows positive birefringence. Examples of a method for obtaining a retardation film using a polymer exhibiting positive birefringence are disclosed in Japanese Patent Application Laid-Open Nos. 2000-23310, 2000-206328, 2002-207123, and the like. Such a stretching method that increases the refractive index in the thickness direction can be used. Specifically, the heat-shrinkable film is adhered to one or both sides of a film containing a polymer exhibiting positive birefringence, and a heat treatment is performed. The film can be shrunk under the action of the shrinkage force of the heat-shrinkable film by heat treatment to shrink the length direction and width direction of the film, thereby increasing the refractive index in the thickness direction, nz> nx A retardation film having a refractive index ellipsoid of> ny can be obtained.

  Thus, the positive biaxial plate used for the second optical compensation layer can be manufactured using a polymer exhibiting either positive or negative birefringence. In general, when using a polymer exhibiting positive birefringence, there are advantages in that there are many types of polymers that can be selected. When using a polymer exhibiting negative birefringence, a polymer exhibiting positive birefringence is provided. Compared with the case of using the film, the film has an advantage in that a retardation film excellent in uniformity in the slow axis direction can be easily obtained due to the stretching method.

  In addition to the above-described film, a commercially available optical film can be used as it is as the retardation film used for the second optical compensation layer. A film obtained by subjecting a commercially available optical film to secondary processing such as stretching and / or relaxation can also be used.

  The light transmittance at a wavelength of 590 nm of the retardation film is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Although the theoretical upper limit of the light transmittance is 100%, surface reflection occurs due to the difference in refractive index between air and the retardation film, and therefore, the upper limit that the light transmittance can be realized is approximately 94%. . The second optical compensation layer as a whole preferably has the same light transmittance.

The absolute value of the photoelastic coefficient of the retardation film is preferably 1.0 × 10 ⁻¹⁰ (m ² / N) or less, more preferably 5.0 × 10 ⁻¹¹ (m ² / N) or less, and still more preferably. Is 3.0 × 10 ⁻¹¹ (m ² / N) or less, particularly preferably 1.0 × 10 ⁻¹¹ (m ² / N) or less. By setting the photoelastic coefficient in such a range, a liquid crystal display device (liquid crystal panel) having excellent optical uniformity and small change in optical characteristics even in an environment such as high temperature and high humidity and excellent durability. Can be obtained. The lower limit of the photoelastic coefficient is not particularly limited, but is generally 5.0 × 10 ⁻¹³ (m ² / N) or more, preferably 1.0 × 10 ⁻¹² (m ² / N) or more. If the photoelastic coefficient is too small, there is a possibility that the expression of the phase difference may be reduced. The photoelastic coefficient is a value intrinsic to a chemical structure such as a polymer, but the photoelastic coefficient can be reduced by copolymerizing or mixing a plurality of components having different signs (positive and negative) of the photoelastic coefficient.

  The thickness of the retardation film can be set to any appropriate value depending on the material for forming the retardation film and the configuration of the second optical compensation layer. When the second optical compensation layer is a retardation film alone, the thickness of the second optical compensation layer is preferably 10 to 250 μm, more preferably 20 to 200 μm, and particularly preferably 30 to 150 μm. By having such a thickness, a second optical compensation layer excellent in mechanical strength and display uniformity can be obtained.

A-4. Third Optical Compensation Layer As described above, the laminated optical film of the present invention can further include a third optical compensation layer. The third optical compensation layer can function as a so-called λ / 4 plate. The third optical compensation layer can convert, for example, linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light) as a λ / 4 plate. The third optical compensation layer can mainly compensate the liquid crystal cell. The in-plane retardation Re ₃ of the third optical compensation layer is preferably 80 to 200 nm, more preferably 90 to 160 nm, still more preferably 110 to 155 nm, and particularly preferably 130 to 150 nm.

A-4-1. Third optical compensation layer (1)
In one embodiment, the third optical compensation layer has a refractive index ellipsoid of nx> ny = nz. Here, “ny = nz” includes not only the case where ny and nz are exactly equal, but also the case where ny and nz are substantially equal. That is, the Nz coefficient (Rth ₃ / Re ₃ ) is more than 0.9 and less than 1.1.

  The third optical compensation layer having a refractive index ellipsoid of nx> ny = nz can be formed of any appropriate material. Specific examples include the liquid crystal material described in the above section A-2. When formed of the liquid crystal material, the thickness is typically 0.5 to 10 μm, preferably 0.5 to 8 μm, and more preferably 0.5 to 5 μm. Another specific example is a stretched polymer film described in the above section A-2. When it is the said stretched film, thickness is 5-55 micrometers typically, Preferably it is 10-50 micrometers, More preferably, it is 15-45 micrometers.

A-4-2. Third optical compensation layer (2)
In another embodiment, the third optical compensation layer has a refractive index ellipsoid of nx>ny> nz. The Nz coefficient (Rth ₃ / Re ₃ ) of the third optical compensation layer is 1.1 or more, preferably 1.1 <Nz <2.0, more preferably 1.3 <Nz <. 1.8.

  The third optical compensation layer having a refractive index ellipsoid of nx> ny> nz can be formed of any appropriate material. Specific examples include stretched films of polymer films. The resin forming the polymer film is preferably a norbornene resin or a polycarbonate resin. Details of these resins are as described above in section A-2.

  The polymer film may include any appropriate other thermoplastic resin. Other thermoplastic resins include polyolefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / styrene resins, polymethyl methacrylate, polyvinyl acetate, and polychlorinated resins. General-purpose plastics such as vinylidene resins; general-purpose engineering plastics such as polyamide resins, polyacetal resins, polycarbonate resins, modified polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins; polyphenylene sulfide resins, polysulfone resins , Polyethersulfone resin, polyetheretherketone resin, polyarylate resin, liquid crystalline resin, polyamideimide resin, polyimide resin, polyester Super engineering plastics such as La fluoroethylene resin and the like.

  Arbitrary appropriate methods can be employ | adopted as a preparation method of a stretched film. Examples of the stretching method include lateral uniaxial stretching, free end uniaxial stretching, fixed end biaxial stretching, fixed end uniaxial stretching, and sequential biaxial stretching. A specific example of the fixed-end biaxial stretching includes a method of stretching a polymer film in the short direction (lateral direction) while running in the longitudinal direction. This method can be apparently lateral uniaxial stretching. These stretching methods can be employed singly or in combination of two or more. For example, after performing free end uniaxial stretching, the method of performing fixed end uniaxial stretching, etc. are mentioned. The stretching temperature is preferably 135 to 165 ° C, more preferably 140 to 160 ° C. The draw ratio is preferably 1.2 to 3.2 times, more preferably 1.3 to 3.1 times. In this case, the thickness is typically 20 to 80 μm, preferably 25 to 75 μm, and more preferably 30 to 60 μm.

  Another specific example of forming the third optical compensation layer having a refractive index ellipsoid of nx> ny> nz includes a non-liquid crystalline material. Non-liquid crystalline polymers are preferred. Specifically, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide are preferable. These polymers may be used alone or in a mixture of two or more. Among these, polyimide is particularly preferable because of high transparency, high orientation, and high stretchability.

  The third optical compensation layer can be typically formed by applying a solution of the non-liquid crystalline polymer to a base film and removing the solvent. In the method for forming the optical compensation layer, a process (for example, a stretching process) for imparting optical biaxiality (nx> ny> nz) is preferably performed. By performing such processing, a difference in refractive index (nx> ny) can be reliably imparted in the surface. In addition, as a specific example of the said polyimide and the specific example of the formation method of the said optical compensation layer, the manufacturing method of the polymer and optical compensation film of Unexamined-Japanese-Patent No. 2004-46065 are mentioned. In this case, the thickness of the third optical compensation layer is typically 0.1 to 10 μm, preferably 0.1 to 8 μm, and more preferably 0.1 to 5 μm.

A-5. Fourth Optical Compensation Layer As described above, the laminated optical film of the present invention can further include a fourth optical compensation layer. In the fourth optical compensation layer, the refractive index ellipsoid shows a 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. Specifically, Re ₄ is less than 10 nm. The thickness direction retardation Rth ₄ of the fourth optical compensation layer can be set to any appropriate value depending on the configuration of the applied liquid crystal panel. Details will be described later in section B-5. The fourth optical compensation layer can mainly compensate the liquid crystal cell.

  The fourth optical compensation layer can be formed of any appropriate material as long as the above characteristics are obtained. A specific example of the fourth optical compensation layer is a cholesteric alignment solidified layer. The “cholesteric alignment solidified layer” refers to a layer in which the constituent molecules of the layer have a helical structure, the helical axis is aligned substantially perpendicular to the plane direction, and the alignment state is fixed. Therefore, the “cholesteric alignment solidified layer” includes not only the case where the liquid crystal compound exhibits a cholesteric liquid crystal phase but also the case where the non-liquid crystal compound has a pseudo structure such as a cholesteric liquid crystal phase. For example, the “cholesteric alignment solidified layer” is obtained by applying a torsion with a chiral agent in a state where the liquid crystal material exhibits a liquid crystal phase and aligning it in a cholesteric structure (spiral structure), and performing a polymerization treatment or a crosslinking treatment in that state. It can be formed by fixing the alignment (cholesteric structure) of the liquid crystal material.

  Specific examples of the cholesteric alignment fixed layer include a cholesteric layer described in JP-A No. 2003-287623.

  The thickness of the fourth optical compensation layer can be set to any appropriate value as long as desired optical characteristics described later can be obtained. When the fourth optical compensation layer is a cholesteric alignment solidified layer, it is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and further preferably 0.5 to 5 μm.

  Another specific example of the material for forming the fourth optical compensation layer is a non-liquid crystalline material. Particularly preferred are non-liquid crystalline polymers. Unlike the liquid crystalline material, such a non-liquid crystalline material can form a film exhibiting an optical uniaxial property of nx = ny> nz by its own property regardless of the orientation of the substrate. As the non-liquid crystalline material, for example, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide are preferable because they are excellent in heat resistance, chemical resistance, transparency, and rigidity. 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.

  Specific examples of the polyimide and the method for forming the fourth optical compensation layer include a polymer and a method for producing an optical compensation film described in JP-A-2004-46065.

  The thickness of the fourth optical compensation layer can be set to any appropriate value as long as desired optical characteristics described later can be obtained. When the fourth optical compensation layer is formed of a non-liquid crystalline material, it is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and still more preferably 0.5 to 5 μm.

  Still another specific example of the material forming the fourth optical compensation layer includes a polymer film formed of a cellulose resin such as triacetyl cellulose (TAC), a norbornene resin, or the like. As the fourth optical compensation layer, a commercially available film can be used as it is. Further, a commercially available film subjected to secondary processing such as stretching and / or shrinking can be used. Commercially available films include, for example, Fuji Photo Film Co., Ltd. Fujitac Series (trade names; ZRF80S, TD80UF, TDY-80UL), Konica Minolta Opto Co., Ltd. trade names “KC8UX2M”, Nippon Zeon Co., Ltd. A trade name “Zeonor”, a product name “Arton” manufactured by JSR Corporation, and the like can be given. The norbornene-based monomer constituting the norbornene-based resin is as described above in the section A-2. Examples of the stretching method for satisfying the above optical characteristics include biaxial stretching (longitudinal and transverse equal magnification stretching).

  The thickness of the fourth optical compensation layer can be set to any appropriate value as long as desired optical characteristics described later can be obtained. When the fourth optical compensation layer is a polymer film formed of a cellulose resin, a norbornene resin or the like, it is preferably 45 to 105 μm, more preferably 55 to 95 μm, and still more preferably 50 to 90 μm.

  Still another specific example of the fourth optical compensation layer includes a laminate having the cholesteric alignment solidified layer and a plastic film layer. Examples of the resin forming the plastic film layer include cellulose resins and norbornene resins. These resins are as described above in this section.

  Any appropriate method can be adopted as a method of laminating the cholesteric alignment solidified layer and the plastic film layer. Specifically, a method of transferring the cholesteric alignment solidified layer to the plastic layer, a method of pasting the cholesteric alignment solidified layer previously formed on the base material and the plastic film layer through an adhesive layer, and the like can be mentioned. A typical example of the adhesive that forms the adhesive layer is a curable adhesive. Typical examples of the curable adhesive include a photocurable adhesive such as an ultraviolet curable adhesive, a moisture curable adhesive, and a thermosetting adhesive. The thickness of the adhesive layer is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm.

A-6. Polarizer Any appropriate polarizer may be adopted as the polarizer according to the purpose. For example, dichroic substances such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product. Among these, a polarizer obtained by adsorbing a dichroic substance such as iodine on a polyvinyl alcohol film and uniaxially stretching is particularly preferable because of its high polarization dichroic ratio. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

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

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

A-7. Protective layer The first protective layer and the second protective layer are formed of any appropriate film that can be used as a protective film for a polarizing plate. Specific examples of the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

  As said (meth) acrylic-type resin, Tg (glass transition temperature) becomes like this. Preferably it is 115 degreeC or more, More preferably, it is 120 degreeC or more, More preferably, it is 125 degreeC or more, Most preferably, it is 130 degreeC or more. It is because it can be excellent in durability. Although the upper limit of Tg of the said (meth) acrylic-type resin is not specifically limited, From viewpoints of a moldability etc., Preferably it is 170 degrees C or less.

As said (meth) acrylic-type resin, arbitrary appropriate (meth) acrylic-type resins can be employ | adopted within the range which does not impair the effect of this invention. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, poly (meth) acrylic acid C _1-6 alkyl such as poly (meth) acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  Specific examples of the (meth) acrylic resin include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. Examples of the resin include high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure is particularly preferable in that it has high heat resistance, high transparency, and high mechanical strength.

  Examples of the (meth) acrylic resin having the lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in JP-A-146084.

  The (meth) acrylic resin having the lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, and still more preferably 10,000 to 500,000. Preferably it is 50000-500000.

  The (meth) acrylic resin having the lactone ring structure has a Tg (glass transition temperature) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, particularly preferably 135 ° C. or higher. Preferably it is 140 degreeC or more. It is because it can be excellent in durability. The upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  In the present specification, “(meth) acrylic” refers to acrylic and / or methacrylic.

  The first protective layer and the second protective layer are preferably transparent and have no color. The thickness direction retardation Rth of the second protective layer is preferably −90 nm to +90 nm, more preferably −80 nm to +80 nm, and still more preferably −70 nm to +70 nm.

  Any appropriate thickness can be adopted as the thickness of the first protective layer and the second protective layer as long as the preferable retardation Rth in the thickness direction can be obtained. The thickness of the second protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 to 500 μm, and still more preferably 5 to 150 μm.

  On the opposite side of the second protective layer from the polarizer, a hard coat treatment, an antireflection treatment, an antisticking treatment, an antiglare treatment, or the like can be performed as necessary.

  The thickness direction retardation (Rth) of the first protective layer provided between the polarizer and the optical compensation layer is preferably smaller than the preferable value. As described above, in the case of a cellulose film generally used as a protective film, for example, a triacetyl cellulose film, the thickness direction retardation (Rth) is about 60 nm at a thickness of 80 μm. Therefore, the first protective layer can be suitably obtained by subjecting the cellulose-based film having a large thickness direction retardation (Rth) to appropriate treatment for reducing the thickness direction retardation (Rth). .

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

  The material constituting the cellulose film is preferably a fatty acid-substituted cellulose polymer such as diacetyl cellulose or triacetyl cellulose. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8, preferably an acetic acid substitution degree of 1.8 to 2.7, more preferably a propionic acid substitution degree of 0.1 to 2.7. By controlling to 1, the thickness direction retardation (Rth) can be controlled to be small.

  By adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose polymer, the thickness direction retardation (Rth) can be controlled to be small. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid-substituted cellulose polymer.

  The processes for reducing the thickness direction retardation (Rth) may be used in appropriate combination. The thickness direction retardation Rth (550) of the first protective layer obtained by performing such treatment is preferably −20 nm to +20 nm, more preferably −10 nm to +10 nm, still more preferably −6 nm to +6 nm, particularly Preferably, it is −3 nm to +3 nm. The in-plane retardation Re (550) of the first protective layer is preferably 0 nm to 10 nm, more preferably 0 nm to 6 nm, and still more preferably 0 nm to 3 nm.

  As the thickness of the first protective layer, any appropriate thickness can be adopted as long as the preferable thickness direction retardation Rth can be obtained. The thickness of the first protective layer is preferably 20 to 200 μm, more preferably 30 to 100 μm, and still more preferably 35 to 95 μm.

A-8. Lamination method Arbitrary appropriate methods can be employ | adopted for the lamination | stacking method of said each layer (film). Specifically, it is laminated via any appropriate pressure-sensitive adhesive layer or adhesive layer. As the said adhesive layer, an acrylic adhesive layer is mentioned typically. The thickness of the acrylic pressure-sensitive adhesive layer is preferably 1 to 30 μm, more preferably 3 to 25 μm.

B. Liquid crystal panel B-1. Overall Configuration of Liquid Crystal Panel FIG. 2A is a schematic cross-sectional view of a liquid crystal panel according to one embodiment of the present invention. The liquid crystal panel 100 includes a liquid crystal cell 20; a laminated optical film 10 ′ of the present invention disposed on one side of the liquid crystal cell 20 (backlight side in the illustrated example); and the other side of the liquid crystal cell 20 (illustrated example). Then, it is provided with the laminated film 30 arrange | positioned in the visual recognition side. The laminated film 30 includes the polarizer 11 and the fifth optical compensation layer 16. In the laminated film 30, a first protective layer is provided between the polarizer 11 and the fifth optical compensation layer 16 as necessary, and the first film is provided on the opposite side of the polarizer 11 from the fifth optical compensation layer 16. Two protective layers are provided. Although not shown, the laminated film 30 may further include any appropriate other optical compensation layer. As shown in the figure, the laminated optical film 10 ′ and the laminated film 30 are arranged such that the side on which the optical compensation layer is provided is the liquid crystal cell 20 side.

  FIG. 2B is a schematic cross-sectional view of a liquid crystal panel according to another embodiment of the present invention. The liquid crystal panel 100 ′ includes the liquid crystal cell 20; the laminated optical film 10 ′ of the present invention disposed on one side of the liquid crystal cell 20 (the backlight side in the illustrated example); and the other side of the liquid crystal cell 20 (see FIG. And a laminated film 30 ′ arranged on the viewing side in the example shown. The laminated film 30 ′ includes the polarizer 11, the fifth optical compensation layer 16, and the sixth optical compensation layer 17. The laminated film 30 ′ is provided with a first protective layer between the polarizer 11 and the fifth optical compensation layer 16 as necessary, and on the opposite side of the polarizer 11 from the first optical compensation layer 12. A second protective layer is provided. Although not shown, the laminated film 30 ′ may further include any appropriate other optical compensation layer. As shown in the figure, the laminated optical film 10 ′ and the laminated film 30 ′ are arranged so that the side on which the optical compensation layer is provided is the liquid crystal cell 20 side.

  Unlike the illustrated example, the laminated optical film 10 may be disposed instead of the laminated optical film 10 ′. Unlike the illustrated example, the laminated optical film 10 ′ (10) may be arranged on the viewing side, and the laminated films 30 and 30 ′ may be arranged on the backlight side.

  The slow axis of the fifth optical compensation layer 16 constituting the laminated films 30 and 30 ′ defines an arbitrary appropriate angle with respect to the absorption axis of the polarizer 11 constituting the laminated films 30 and 30 ′. Thus, they are laminated. The angle is preferably 30 to 60 °, more preferably 35 to 55 °, particularly preferably 40 to 50 °, and most preferably 43 to 47 °.

  The absorption axes of the polarizers 11 and 11 arranged on both sides of the liquid crystal cell 20 of the liquid crystal panels 100 and 100 'are preferably arranged so as to be substantially orthogonal.

B-2. Liquid Crystal Cell The liquid crystal cell 20 includes a pair of substrates 21 and 21 ′ and a liquid crystal layer 22 as a display medium sandwiched between the substrates 21 and 21 ′. One substrate (color filter substrate) 21 is provided with a color filter and a black matrix (both not shown). On the other substrate (active matrix substrate) 21 ′, a switching element (typically TFT) (not shown) for controlling the electro-optical characteristics of the liquid crystal and a scanning line (not shown) for supplying a gate signal to this switching element. ) And a signal line (not shown) for supplying a source signal, and a pixel electrode (not shown). The color filter may be provided on the active matrix substrate 21 ′ side. A distance (cell gap) between the substrates 21 and 21 'is controlled by a spacer (not shown). For example, an alignment film (not shown) made of polyimide is provided on the side of the substrates 21, 21 ′ in contact with the liquid crystal layer 22.

  Any appropriate drive mode can be adopted as the drive mode of the liquid crystal cell 20. The VA mode is preferable. FIG. 3 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in the VA mode. As shown in FIG. 3A, when no voltage is applied, the liquid crystal molecules are aligned perpendicular to the surfaces of the substrates 21 and 21 '. Such vertical alignment can be realized by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film (not shown) is formed. When light is incident from the surface of one substrate 21 in such a state, linearly polarized light that has passed through one polarizer 11 and entered the liquid crystal layer 22 has a long axis of liquid crystal molecules that are vertically aligned. Proceed along the direction. Since birefringence does not occur in the major axis direction of the liquid crystal molecules, the incident light travels without changing the polarization direction and is absorbed by the other polarizer 11 having a polarization axis orthogonal to one polarizer 11. This provides a dark display when no voltage is applied (normally black mode). As shown in FIG. 3B, when a voltage is applied between the electrodes, the long axes of the liquid crystal molecules are aligned parallel to the substrate surface. The liquid crystal molecules in this state exhibit birefringence with respect to linearly polarized light that has passed through one polarizer 11 and entered the liquid crystal layer 22, and the polarization state of the incident light changes in accordance with the inclination of the liquid crystal molecules. . The light passing through the liquid crystal layer when a predetermined maximum voltage is applied becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °, and thus the light is transmitted through the other polarizer 11 to obtain a bright display. When the voltage is not applied again, the display can be returned to the dark state by the orientation regulating force. In addition, gradation display is possible by changing the applied voltage to control the inclination of the liquid crystal molecules to change the transmitted light intensity from the other polarizer 11.

B-3. Fifth Optical Compensation Layer The fifth optical compensation layer 16 can function as a so-called λ / 4 plate. As the λ / 4 plate, for example, the fifth optical compensation layer can convert linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The fifth optical compensation layer can mainly compensate the liquid crystal cell. The fifth optical compensation layer may have the same optical characteristics (refractive index ellipsoid, in-plane retardation, Nz coefficient, etc.) as the third optical compensation layer. Further, the fifth optical compensation layer can be formed of the same material as the third optical compensation layer.

B-4. Sixth Optical Compensation Layer The sixth optical compensation layer 17 has a refractive index ellipsoid of nx = ny> nz. The sixth optical compensation layer can mainly compensate the liquid crystal cell. The thickness direction retardation Rth ₆ of the sixth optical compensation layer can be set to any appropriate value depending on the configuration of the liquid crystal panel and the like. Details will be described in the section B-5. The sixth optical compensation layer can be formed of the same material as the fourth optical compensation layer.

B-5. Regarding retardation in thickness direction of fourth optical compensation layer and sixth optical compensation layer The fourth optical compensation layer and the sixth optical compensation layer have refractive index ellipsoids of nx = ny> nz. A layer having such a refractive index ellipsoid may be referred to as a “negative C plate”. As shown in FIG. 2A, in the liquid crystal panel, when a single negative C plate is provided (fourth optical compensation layer 15 in the illustrated example), the thickness direction retardation Rth is preferably 50 to The thickness is 600 nm, more preferably 100 to 540 nm, and particularly preferably 150 to 500 nm. On the other hand, as shown in FIG. 2B, in the liquid crystal panel, when a plurality of negative C plates are provided (in the illustrated example, the fourth optical compensation layer 15 and the sixth optical compensation layer 17), The sum of the thickness direction retardation Rth is preferably 50 to 600 nm, more preferably 100 to 540 nm, and particularly preferably 150 to 500 nm. The Rth of each negative C plate can be set to any appropriate value. Specifically, as shown in FIG. 2B, when the fourth optical compensation layer and the sixth optical compensation layer are provided as the negative C plate (when two layers are provided), Rth ₄ Is preferably 25 to 300 nm, more preferably 50 to 270 nm, and particularly preferably 75 to 250 nm. Rth ₆ is preferably 25 to 300 nm, more preferably 50 to 270 nm, and particularly preferably 75 to 250 nm.

B-6. Lamination method Arbitrary appropriate methods can be employ | adopted for the lamination | stacking method of said each layer (film). Specifically, it is laminated via any appropriate pressure-sensitive adhesive layer or adhesive layer. A typical example of the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer. The thickness of the acrylic pressure-sensitive adhesive layer provided on both sides of the liquid crystal cell is preferably 1 μm to 100 μm, more preferably 1 μm to 50 μm, and further preferably 3 μm to 30 μm. The thickness of the other acrylic pressure-sensitive adhesive layer is preferably 1 to 30 μm, more preferably 3 to 25 μm.

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

(1) Measurement of phase difference value The phase difference value was automatically measured using KOBRA-WPR manufactured by Oji Scientific. The measurement wavelength was 590 nm or 550 nm, and the measurement temperature was 23 ° C.
(2) Contrast measurement 1
Computer simulations were performed on the liquid crystal panels of the examples and comparative examples using the optical characteristic parameters of the optical compensation layers actually fabricated and measured. For the simulation, a simulator for liquid crystal display “LCD MASTER” manufactured by Shintech Co., Ltd. was used.
(3) Contrast measurement 2
A white image and a black image were displayed on the liquid crystal display device, and measurement was carried out using a product name “Conoscope” manufactured by AUTRONIC MELCHERS.

[Example 1]
(Polarizer)
The polyvinyl alcohol film was dyed in an aqueous solution containing iodine and then uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to obtain a polarizer. A triacetyl cellulose film (thickness 40 μm, manufactured by Konica Minolta, Inc., trade name: KC4UYW) as a protective layer was attached to both surfaces of this polarizer via a polyvinyl alcohol adhesive (thickness 0.1 μm). The in-plane retardation Re (550) of the protective layer was 0.9 nm, and the thickness direction retardation Rth (550) was 1.2 nm. In this way, a polarizing plate was produced. Re (550) represents a value when measured with light having a wavelength of 550 nm at 23 ° C.

(First optical compensation layer)
By uniaxially stretching a long norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name Zeonor, thickness 40 μm, photoelastic coefficient 3.10 × 10 ⁻¹² m ² / N) at 140 ° C. by 1.52 times, A long film was prepared. The thickness of the obtained film was 35 μm, the in-plane retardation Re ₁ was 110 nm, and the thickness direction retardation Rth ₁ was 110 nm. The obtained film was punched into a size corresponding to a liquid crystal cell described later to obtain a first optical compensation layer.

(Second optical compensation layer)
Styrene-maleic anhydride copolymer (manufactured by Nova Chemical Japan Co., Ltd., trade name “Dylark D232”) is extruded at 270 ° C. using a single screw extruder and a T die, and melted in a sheet form. The resin was cooled with a cooling drum to obtain a film having a thickness of 100 μm. This film was uniaxially stretched in the transport direction at a temperature of 130 ° C. and a stretch ratio of 1.6 times using a roll stretching machine to obtain a film having a fast axis in the transport direction (longitudinal stretching step). .
Using a tenter stretching machine, the obtained film was uniaxially stretched at a fixed end in the width direction so that the film width was 1.6 times the film width after the longitudinal stretching at a temperature of 135 ° C., and the thickness was 50 μm. A biaxially stretched film was obtained (transverse stretching step).
The retardation film thus obtained has a fast axis in the transport direction, the refractive index ellipsoid shows a relationship of nz>nx> ny, the in-plane retardation Re ₂ is 19 nm, and the thickness direction position is The phase difference Rth ₂ was −80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was −4.2. The obtained retardation film was punched into a size corresponding to a liquid crystal cell described later to obtain a second optical compensation layer.

(Third optical compensation layer)
By uniaxially stretching a long norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name Zeonor, thickness 40 μm, photoelastic coefficient 3.10 × 10 ⁻¹² m ² / N) at 140 ° C. by 1.52 times, A long film was prepared. The thickness of the obtained film was 35 μm, the in-plane retardation Re ₃ was 140 nm, and the thickness direction retardation Rth ₃ was 140 nm. The obtained film was punched out to a size corresponding to a liquid crystal cell described later to obtain a third optical compensation layer.

(Fourth optical compensation layer)
90 parts by weight of a nematic liquid crystalline compound represented by the following chemical formula (1), 10 parts by weight of a chiral agent represented by the following chemical formula (2), 5 parts by weight of a photopolymerization initiator (Irgacure 907: manufactured by Ciba Specialty Chemicals), and 300 parts by weight of methyl ethyl ketone was mixed uniformly to prepare a liquid crystal coating solution. Next, this liquid crystal coating solution is coated on a substrate (biaxially stretched PET film), heat-treated at 80 ° C. for 3 minutes, and then subjected to polymerization treatment by irradiating with ultraviolet rays, and a fourth optical compensation layer and A cholesteric alignment solidified layer was formed. The thickness of the cholesteric alignment fixed layer was 2.2 μm, the thickness direction retardation Rth ₄ was 120 nm, and the in-plane retardation Re ₄ was substantially zero.

(Fifth optical compensation layer)
A film obtained in the same manner as the third optical compensation layer was used as a fifth optical compensation layer (Re ₅ : 140 nm, Rth ₅ : 140 nm).

(Sixth optical compensation layer)
A cholesteric alignment fixed layer obtained in the same manner as the fourth optical compensation layer was defined as a _sixth optical compensation layer (Re ₆ : substantially zero, Rth ₆ : 120 nm).

(Laminated optical film A)
A cholesteric alignment solidified layer to be the fourth optical compensation layer is adhered to the third optical compensation layer obtained above with an isocyanate-based adhesive (thickness 5 μm), and the substrate (biaxially stretched PET film) is removed. Thus, the laminate 1 in which the cholesteric alignment solidified layer is transferred to the third optical compensation layer is obtained.
On the third optical compensation layer side of the laminate 1, a second optical compensation layer, a first optical compensation layer, and a polarizing plate are laminated in this order via an acrylic adhesive (thickness: 12 μm). At this time, the first optical compensation layer is laminated so that the slow axis of the first optical compensation layer is orthogonal to the absorption axis of the polarizer of the polarizing plate, and the slow axis of the second optical compensation layer is absorbed by the polarizer of the polarizing plate. The third optical compensation layer is laminated so that the slow axis of the third optical compensation layer is 45 ° clockwise with respect to the absorption axis of the polarizer of the polarizing plate. In this way, the laminated film A is produced.

(Laminated film B)
A cholesteric alignment solidified layer to be the sixth optical compensation layer is adhered to the fifth optical compensation layer obtained above with an isocyanate-based adhesive (thickness 5 μm), and the substrate (biaxially stretched PET film) is removed. Thus, the laminate 2 in which the cholesteric alignment solidified layer is transferred to the fifth optical compensation layer is obtained.
A polarizing plate is laminated on the fifth optical compensation layer side of the laminate 2 via an acrylic pressure-sensitive adhesive (thickness: 12 μm). At this time, the fifth optical compensation layer is laminated so that the slow axis is 45 ° clockwise with respect to the absorption axis of the polarizer of the polarizing plate. In this way, the laminated film B is produced.

(LCD panel)
A liquid crystal cell is removed from a Sony PlayStation Portable (VA mode liquid crystal cell mounted), and the laminated optical film A is attached to the backlight side of the liquid crystal cell via an acrylic adhesive (thickness 20 μm). At this time, the fourth optical compensation layer was attached so as to be on the liquid crystal cell side. Moreover, the said laminated | multilayer film B is affixed on the visual recognition side of a liquid crystal cell through an acrylic adhesive (thickness 20 micrometers). At this time, the sixth optical compensation layer is attached so as to be on the liquid crystal cell side. Moreover, it laminates | stacks so that the absorption axis of the polarizer of laminated optical film A and the absorption axis of the polarizer of laminated film B may mutually orthogonally cross. Specifically, the slow axis of the fifth optical compensation layer is 45 ° clockwise and the slow axis of the third optical compensation layer is clockwise with respect to the absorption axis of the polarizer on the viewing side as a reference (0 °). Lamination is performed so that the slow axis of the second optical compensation layer is 0 °, the slow axis of the first optical compensation layer is 0 °, and the absorption axis of the polarizer on the backlight side is 90 °. In this way, a liquid crystal panel is produced.
Computer simulation was performed on the viewing angle dependence of the contrast of a liquid crystal display device using this liquid crystal panel. The results are shown in FIG.

[Example 2]
(Laminated optical film C)
A laminated optical film C is obtained in the same manner as the laminated optical film A except that the second optical compensation layer is laminated so that the slow axis of the second optical compensation layer is parallel to the absorption axis of the polarizer of the polarizing plate.

(LCD panel)
A liquid crystal panel is obtained in the same manner as in Example 1 except that the laminated optical film C is used instead of the laminated optical film A. Specifically, the slow axis of the fifth optical compensation layer is 45 ° clockwise and the slow axis of the third optical compensation layer is clockwise with respect to the absorption axis of the polarizer on the viewing side as a reference (0 °). 135 °, laminated so that the slow axis of the second optical compensation layer is 90 °, the slow axis of the first optical compensation layer is 0 °, and the absorption axis of the polarizer on the backlight side is 90 °. Get a liquid crystal panel.
Computer simulation was performed on the viewing angle dependence of the contrast of a liquid crystal display device using this liquid crystal panel. The results are shown in FIG.

[Comparative Example 1]
(Laminated film D)
A laminated film D was obtained in the same manner as the laminated optical film A, except that the first optical compensation layer and the second optical compensation layer were not laminated.

(LCD panel)
A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated film D was used instead of the laminated optical film A. Specifically, the slow axis of the fifth optical compensation layer is 45 ° clockwise and the slow axis of the third optical compensation layer is clockwise with respect to the absorption axis of the polarizer on the viewing side as a reference (0 °). A liquid crystal panel was manufactured by stacking the polarizer so that the absorption axis of the polarizer on the backlight side was 90 °.
Computer simulation was performed on the viewing angle dependence of the contrast of a liquid crystal display device using this liquid crystal panel. The results are shown in FIG. Further, the viewing angle dependence of contrast of a liquid crystal display device manufactured using the liquid crystal panel thus obtained was measured. The results are shown in FIG.

[Comparative Example 2]
(Laminated film E)
A laminated film E was obtained in the same manner as the laminated optical film A, except that the first optical compensation layer was not laminated.

(LCD panel)
A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated film E was used in place of the laminated optical film A. Specifically, the slow axis of the fifth optical compensation layer is 45 ° clockwise and the slow axis of the third optical compensation layer is clockwise with respect to the absorption axis of the polarizer on the viewing side as a reference (0 °). A liquid crystal panel was manufactured by stacking so that the slow axis of the second optical compensation layer was 0 ° and the absorption axis of the polarizer on the backlight side was 90 °.
Computer simulation was performed on the viewing angle dependence of the contrast of a liquid crystal display device using this liquid crystal panel. The results are shown in FIG. Further, the viewing angle dependence of contrast of a liquid crystal display device manufactured using the liquid crystal panel thus obtained was measured. The results are shown in FIG.

[Comparative Example 3]
(Laminated film F)
A laminated film F is obtained in the same manner as the laminated optical film C except that the first optical compensation layer is not laminated.

(LCD panel)
A liquid crystal panel is obtained in the same manner as in Example 2 except that the laminated film F is used instead of the laminated optical film A. Specifically, the slow axis of the fifth optical compensation layer is 45 ° clockwise and the slow axis of the third optical compensation layer is clockwise with respect to the absorption axis of the polarizer on the viewing side as a reference (0 °). A liquid crystal panel is manufactured by stacking so that the slow axis of the second optical compensation layer is 90 ° and the absorption axis of the polarizer on the backlight side is 90 °.
Computer simulation was performed on the viewing angle dependence of the contrast of a liquid crystal display device using this liquid crystal panel. The results are shown in FIG.

The contour lines shown in the computer simulation results (FIGS. 4 to 6, 8, and 10) indicate 100, 50, 40, 30, 20, and 10, respectively, from the inside.
The overall configurations of the panels of Examples 1 and 2 and Comparative Examples 1 to 3 are summarized in Table 1. The angle (clockwise) when the absorption axis of the viewing side polarizer is 0 ° is also shown.

  As is apparent from FIGS. 4 to 10, the liquid crystal panels of Examples 1 and 2 of the present invention were superior in contrast to the liquid crystal panels of Comparative Examples 1 to 3. Moreover, it was confirmed that the liquid crystal panel of the Example of this invention has a small color shift compared with the liquid crystal panel of a comparative example.

  The liquid crystal panel and the liquid crystal display device of the present invention can be suitably applied to a mobile phone, a personal digital assistant (PDA), a liquid crystal television, a personal computer, and the like.

(A) is a schematic sectional drawing of the laminated optical film by preferable embodiment of this invention, (b) is a schematic sectional drawing of the laminated optical film by another preferable embodiment of this invention. (A) is a schematic sectional drawing of the liquid crystal panel by one Embodiment of this invention, (b) is a schematic sectional drawing of the liquid crystal panel by another preferable embodiment of this invention. When the liquid crystal display device of this invention employ | adopts a VA mode liquid crystal cell, it is a schematic sectional drawing explaining the orientation state of the liquid crystal molecule of a liquid crystal layer. It is the result of the computer simulation about the viewing angle dependence of the contrast of the liquid crystal panel of Example 1 of this invention. It is the result of the computer simulation about the viewing angle dependence of the contrast of the liquid crystal panel of Example 2 of this invention. It is the result of the computer simulation about the viewing angle dependence of the contrast of the liquid crystal panel of the comparative example 1. 6 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel of Comparative Example 1. FIG. It is the result of the computer simulation about the viewing angle dependence of the contrast of the liquid crystal panel of the comparative example 2. 10 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel of Comparative Example 2. FIG. It is the result of the computer simulation about the viewing angle dependence of the contrast of the liquid crystal panel of the comparative example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated optical film 10 'Laminated optical film 11 Polarizer 12 1st optical compensation layer 13 2nd optical compensation layer 14 3rd optical compensation layer 15 4th optical compensation layer 16 5th optical compensation layer 17 6th Optical compensation layer 20 liquid crystal cell 30 laminated film 100 liquid crystal panel 100 ′ liquid crystal panel

Claims (8)

A polarizer,
A first optical compensation layer having a refractive index ellipsoid showing a relationship of nx> ny = nz;
A refractive index ellipsoid comprising a second optical compensation layer exhibiting a relationship of nz>nx> ny,
The in-plane retardation Re _{1 of the} first optical compensation layer is 80 to 150 nm,
The in-plane retardation Re ₂ of the second optical compensation layer satisfies a relationship of 10 nm <Re ₂ <50 nm,
The absorption axis of the polarizer and the slow axis of the first optical compensation layer are arranged in parallel or orthogonal to each other,
A laminated optical film in which the absorption axis of the polarizer and the slow axis of the second optical compensation layer are arranged so as to be parallel or orthogonal to each other.   The laminated optical film according to claim 1, wherein the Nz coefficient of the second optical compensation layer is -1.0 or less. The laminated optical film according to claim 1 or 2 , further comprising a third optical compensation layer whose refractive index ellipsoid shows a relationship of nx> ny = nz or nx>ny> nz. The laminated optical film according to claim 3 , wherein an in-plane retardation Re _{3 of} the third optical compensation layer is 80 to 200 nm. Refractive index ellipsoid further comprises a fourth optical compensation layer having a relationship of nx = ny> nz, laminated optical film according to any one of claims 1 to 4. It includes a liquid crystal cell, and a laminated optical film according to one of claims 1 5 noise, liquid crystal panel. The liquid crystal panel according to claim 6 , wherein the liquid crystal cell is in a VA mode. To claim 6 or 7 comprising a liquid crystal panel according liquid crystal display device.