JP4761399B2 - Laminated optical film, liquid crystal panel and liquid crystal display device using laminated optical film - Google Patents

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 including a polarizer and at least three optical compensation layers, a liquid crystal panel using the laminated optical film, and a liquid crystal display device.

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

  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 nz> nx = ny, and a refractive index ellipsoid in a relationship of nx> ny = nz. A second optical compensation layer having an inner phase difference Re ₂ of 80 to 300 nm and a third optical element having a refractive index ellipsoid of nx>ny> nz and an in-plane phase difference Re ₃ of 80 to 200 nm. Compensation layers are provided at least in this order, and the absorption axis of the polarizer and the slow axis of the second optical compensation layer are parallel.

  The fourth optical compensation layer is further provided on the opposite side of the third optical compensation layer from the second optical compensation layer, and the refractive index ellipsoid shows 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 laminated optical film is disposed on the backlight side.

In a preferred embodiment, a laminated film comprising a polarizer and a fifth optical compensation layer having a refractive index ellipsoid of nx>ny> nz and an in-plane retardation Re ₅ of 80 to 200 nm is visually recognized. Arranged on the side.

  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.

  As described above, according to the present invention, by arranging the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer having the above optical characteristics at a predetermined angle, the screen contrast And 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 (that is, the slow axis direction), “ny” is the refractive index in the direction perpendicular to the slow axis in the plane, and “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. Further, the subscript “1” attached to the terms and symbols described in the present specification represents the first optical compensation layer, the subscript “2” represents the second optical compensation layer, and the subscript. “3” represents the third optical compensation layer, and the subscript “4” represents the fourth 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 / 2 plate The λ / 2 plate is an electro-optic birefringent plate that serves to rotate the polarization plane of the light beam, and ½ wavelength between linearly polarized light that vibrates in directions perpendicular to each other. It has the function which produces the optical path difference of. That is, it acts to shift the phase between the ordinary ray component and the extraordinary ray component by a half cycle.
(6) λ / 4 plate The λ / 4 plate is an electro-optic birefringent plate that serves to rotate the polarization plane of the light beam, and ¼ wavelength between linearly polarized light that vibrates in directions perpendicular to each other. It has the function which produces the optical path difference of. That is, it means that the phase between the ordinary ray component and the extraordinary ray component acts so as to be shifted by a quarter cycle and converts circularly polarized light into plane polarized light (or plane polarized light into circularly polarized light).

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, a second optical compensation layer 13, and a third optical compensation layer 14 in this order. 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, and a third optical compensation layer 14 in this order. The laminated optical film 10 ′ further includes a fourth optical compensation layer 15. In the illustrated example, the fourth optical compensation layer 15 is disposed on the opposite side of the third optical compensation layer 14 from the second optical compensation layer 13. Although not shown in FIGS. 1A and 1B, a first protective layer is provided between the polarizer 11 and the first optical compensation layer 12 as necessary, so that the first of the polarizer 11 is provided. A second protective layer is provided on the opposite side of the optical compensation layer 12. In addition, the laminated optical film of the present invention may further include any appropriate optical compensation layer as necessary.

  The second optical compensation layer 13 has a refractive index ellipsoid of nx> ny = nz. The second optical compensation layer 13 is laminated so that its slow axis is parallel to the absorption axis of the polarizer 11. In the present specification, the term “parallel” includes a case where the surfaces are substantially parallel. Here, “substantially parallel” includes the case of 0 ° ± 3.0 °, preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. The third optical compensation layer 14 has a refractive index ellipsoid of nx> ny> nz. The slow axis of the third optical compensation layer 14 is laminated so as to define any appropriate angle with respect to the absorption axis of the polarizer 11. The angle is preferably 30 to 60 °, more preferably 35 to 55 °, particularly preferably 40 to 50 °, and most preferably 43 to 47 °.

  The total thickness of the laminated optical film of the present invention is preferably 250 to 410 μm, more preferably 255 to 405 μm, and particularly preferably 260 to 400 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 12 has a refractive index ellipsoid of nz> nx = ny. The thickness direction retardation Rth ₁ of the first optical compensation layer is preferably −50 to −300 nm, more preferably −70 to −250 nm, particularly preferably −90 to −200 nm, and most preferably −100 to −180 nm. It is. 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. That is, Re ₁ is less than 10 nm.

  The first optical compensation layer can be formed of any appropriate material. Preferably, it consists of a film containing a liquid crystal material fixed in homeotropic alignment. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the method for forming the liquid crystal compound and the optical compensation layer include the liquid crystal compounds described in JP-A-2002-333642 [0020] to [0042] and the method for forming the film. In this case, the thickness is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 0.5 to 5 μm.

A-3. Second Optical Compensation Layer The second optical compensation layer 13 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 ₂ / Re ₂ ) is more than 0.9 and less than 1.1. Plane retardation Re ₂ of the second optical compensation layer is 80 to 300 nm, preferably 80 to 200 nm, more preferably 100 to 180 nm, particularly preferably 120 to 160 nm. The second optical compensation layer can compensate the optical axis of the polarizer. As described above, by arranging the second optical compensation layer so that the slow axis thereof is parallel to the absorption axis of the polarizer, the screen contrast when viewed from an oblique direction can be improved. . As described above, it is one of the features of the present invention that the slow axis of the second optical compensation layer is parallel to the absorption axis of the polarizer.

  As a material for forming the second optical compensation layer, any appropriate material can be adopted as long as the above characteristics are obtained. For example, the second optical compensation layer showing a refractive index ellipsoid of nx> ny = nz can be formed by a stretched 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 A second 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 second 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 particularly preferably 15 to 45 μm.

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

  Another specific example of the material for forming the second optical compensation layer is a liquid crystal material. Preferably, it is a liquid crystal material (nematic liquid crystal) whose liquid crystal phase is a nematic phase. 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. Therefore, in the formed second optical compensation layer, for example, 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 second 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 second optical compensation layer include monomers and methods described in JP-A-2006-178389.

  The thickness of the second optical compensation layer can be set so that desired optical characteristics can be obtained. When the second 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 particularly preferably 0.5 to 5 μm.

A-4. Third Optical Compensation Layer The third optical compensation layer 14 has a refractive index ellipsoid of nx>ny> nz. The in-plane retardation Re ₃ of the third optical compensation layer is 80 to 200 nm, preferably 100 to 200 nm, and particularly preferably 110 to 150 nm. That is, it can function as a 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 Nz coefficient (Rth ₃ / Re ₃ ) is preferably 1 <Nz <2, more preferably 1 <Nz <1.8.

  The third optical compensation layer 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 the section A-3. Arbitrary appropriate methods can be employ | adopted as a preparation method of a stretched film. Examples of the stretching method include lateral uniaxial stretching, fixed end biaxial 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. 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 the material forming the third optical compensation layer is a non-liquid crystalline material. A non-liquid crystalline polymer is preferable. 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 crystal polymer to a base film and removing the solvent. In the method for forming the third optical compensation layer, preferably, a process (for example, a stretching process) for imparting optical biaxiality (nx> ny> nz) is 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 3rd 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 is typically 0.1 to 10 μm, more preferably 0.1 to 8 μm, and particularly 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. By providing the fourth optical compensation layer, the screen contrast can be further improved and the color shift can be further reduced. The fourth optical compensation layer 15 has a refractive index ellipsoid 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. That is, 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-4, but when the fourth optical compensation layer is disposed only on one side of the liquid crystal cell, the thickness direction retardation Rth ₄ is preferably 10 to 300 nm, More preferably, it is 10-200 nm, Most preferably, it is 30-150 nm. On the other hand, when the fourth optical compensation layer is disposed on both sides of the liquid crystal cell, the thickness direction retardation Rth ₄ is preferably 5 to 150 nm, more preferably 5 to 100 nm, and particularly preferably 15 to 75 nm.

  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 the desired optical characteristics are obtained. When the fourth optical compensation layer is a cholesteric alignment fixed layer, it is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and particularly 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 a 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 the desired optical characteristics are 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 particularly 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”, manufactured by Nippon Zeon Co., Ltd. A trade name “Zeonor”, a product name “Arton” manufactured by JSR Corporation, and the like can be given. The norbornene monomer constituting the norbornene resin is as described above in the section A-2-1. 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 the desired optical characteristics are obtained. When the fourth optical compensation layer is a polymer film formed of a cellulose resin, a norbornene resin, or the like, the thickness is preferably 45 to 105 μm, more preferably 55 to 95 μm, and particularly 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. 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 employed as the polarizer 11 depending on 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. The upper limit value of Tg of the (meth) acrylic resin is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

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 a 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., most preferably. Is 140 ° C. or higher. 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 particularly 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 particularly 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 further smaller than the above preferred value. In the case of a cellulose film generally used as a protective film, for example, in the case of 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 treatment method can be adopted as the treatment for reducing the retardation (Rth) in the thickness direction. 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 treatments 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 such treatment is preferably −20 nm to +20 nm, more preferably −10 nm to +10 nm, particularly preferably −6 nm to +6 nm, and most preferably Preferably, it is −3 nm to +3 nm. The in-plane retardation Re (550) of the first protective layer is preferably 0 nm or more and 10 nm or less, more preferably 0 nm or more and 6 nm or less, and particularly preferably 0 nm or more and 3 nm or less.

  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 sectional view of a liquid crystal panel according to a preferred embodiment of the present invention. The liquid crystal panel 100 includes a liquid crystal cell 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 one 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 present embodiment, the refractive index ellipsoid of the fifth optical compensation layer 16 shows a relationship of nx>ny> nz, and the in-plane retardation Re ₅ is 80 to 200 nm. 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 a 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 one side of the liquid crystal cell 20 (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 fourth optical compensation layer 15. 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 panel 100 are preferably arranged so as to be substantially orthogonal. Here, “substantially orthogonal” includes the case of 90 ° ± 3.0 °, preferably 90 ° ± 1.0 °, more preferably 90 ° ± 0.5 °.

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 In the fifth optical compensation layer 16, preferably, the refractive index ellipsoid has a relationship of nx>ny> nz, and the in-plane retardation Re ₅ is 80 to 200 nm. That is, it can function as a λ / 4 plate. As the fifth optical compensation layer, the same layer as the third optical compensation layer can be adopted.

B-4. Regarding the retardation in the thickness direction of the fourth optical compensation layer As shown in FIG. 2A, when the fourth optical compensation layer 15 is disposed only on one side of the liquid crystal cell 20, The thickness direction retardation Rth ₄ of the optical compensation layer is preferably 10 to 300 nm, more preferably 10 to 200 nm, and particularly preferably 30 to 150 nm. On the other hand, as shown in FIG. 2B, when the fourth optical compensation layer 15 is arranged on both sides of the liquid crystal cell 20, the thickness direction retardation Rth ₄ of each of the fourth optical compensation layers is: Preferably, it is substantially half of the retardation in the thickness direction when it is arranged on one side. That is, it is preferably 5 to 150 nm, more preferably 5 to 100 nm, and particularly preferably 15 to 75 nm.

B-5. 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.

  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 performed using a product name “EZ Contrast 160D” manufactured by ELDIM.

[Example 1]
(Preparation of polarizing plate)
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 (first protective layer and second protective layer) is coated on each surface of the polarizer with a polyvinyl alcohol-based adhesive ( 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. Here, Re (550) represents a value when measured with light having a wavelength of 550 nm at 23 ° C.

(Preparation of the first optical compensation layer)
20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (1) (numbers 65 and 35 in the formula indicate mol% of the monomer units and are represented by block polymer for convenience: weight average molecular weight 5000), Dissolve 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name: Palicolor LC242) and 5 parts by weight of a photopolymerization initiator (trade name: Irgacure 907, manufactured by Ciba Specialty Chemicals) in 200 parts by weight of cyclopentanone. Thus, a liquid crystal coating solution was prepared. And after apply | coating the said coating liquid to a base film (norbornene-type resin film: Nippon Zeon Co., Ltd. brand name Zeonor) with the bar coater, the liquid crystal was orientated by heating and drying at 80 degreeC for 4 minutes. By irradiating the liquid crystal layer with ultraviolet rays and curing the liquid crystal layer, a liquid crystal solidified layer serving as a first optical compensation layer was formed on the substrate. The in-plane retardation of this layer was substantially zero, and the thickness direction retardation Rth ₁ was −140 nm.

(Preparation of second 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. This film had a thickness of 35 μm, an in-plane retardation Re ₂ of 140 nm, and a thickness direction retardation Rth ₂ of 140 nm. The obtained film was punched out to a size corresponding to a liquid crystal cell described later to obtain a second optical compensation layer.

(Preparation of third optical compensation layer)
A long norbornene-based resin film (manufactured by Nippon Zeon Co., Ltd., trade name: Zeonor, thickness 60 μm, photoelastic coefficient 3.1 × 10 ⁻¹² m ² / N) is biaxially stretched at 150 ° C. to 1.55 times. As a result, a long film was produced. The in-plane retardation Re ₃ of this film was 140 nm, the thickness direction retardation Rth ₃ was 217 nm, and the Nz coefficient (Rth ₃ / Re ₃ ) was 1.55. The obtained film was punched out to a size corresponding to a liquid crystal cell described later to obtain a third optical compensation layer.

(Production of fifth optical compensation layer)
The same film as the third optical compensation layer was used.

(Preparation of laminated film A)
The polarizing plate obtained above and the fifth optical compensation layer are laminated. Here, 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. The polarizing plate and the fifth optical compensation layer are laminated via an acrylic pressure-sensitive adhesive (thickness: 12 μm). In this way, the laminated film A is produced.

(Preparation of laminated optical film B)
A liquid crystal solidified layer to be the first optical compensation layer was adhered to the second optical compensation layer obtained above with an isocyanate-based adhesive (thickness 5 μm), and the substrate (norbornene-based resin film) was removed. Then, a laminate in which the first optical compensation layer is transferred to the second optical compensation layer is obtained. The third optical compensation layer obtained above is laminated on the second optical compensation layer side of this laminate via an acrylic pressure-sensitive adhesive (thickness 12 μm), and the acrylic optical system is laminated on the first optical compensation layer side. The polarizing plate obtained above is laminated through an adhesive (thickness: 12 μm). At this time, 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, and the slow axis of the third optical compensation layer is of the polarizer of the polarizing plate. Lamination is performed so as to be 45 ° clockwise with respect to the absorption axis. In this way, the laminated optical film B is produced.

(Production of liquid crystal panel)
A liquid crystal cell is removed from a Sony PlayStation Portable (VA mode liquid crystal cell mounted), and the laminated film A is attached to the viewing side of the liquid crystal cell via an acrylic adhesive (thickness 20 μm). At this time, the fifth optical compensation layer is attached so as to be on the liquid crystal cell side. Moreover, the said laminated optical film B is affixed on the backlight side of a liquid crystal cell through an acrylic adhesive (thickness 20 micrometers). At this time, the third optical compensation layer is attached so as to be on the liquid crystal cell side. Further, lamination is performed so that the absorption axis of the polarizer of the laminated film A and the absorption axis of the polarizer of the laminated optical film B are substantially orthogonal to each other. Specifically, with the absorption axis of the polarizer on the backlight side as a reference (0 °), the slow axis of the second optical compensation layer is 0 ° counterclockwise, and the slow phase of the third optical compensation layer Lamination is performed so that the axis is 45 °, the slow axis of the fifth optical compensation layer is 135 °, and the absorption axis of the polarizer on the viewing side is 90 °. In this way, a liquid crystal panel is produced.
Computer simulation was performed on the viewing angle dependence of contrast of a liquid crystal display device using such a liquid crystal panel. The results are shown in FIG.

[Example 2]
(Fabrication of the fourth optical compensation layer)
90 parts by weight of a nematic liquid crystalline compound represented by the following chemical formula (2), 10 parts by weight of a chiral agent represented by the following chemical formula (3), 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 solidified layer was 1.8 μm, the thickness direction retardation Rth ₄ was 80 nm, and the in-plane retardation Re ₄ was substantially zero.

(Preparation of laminated optical film C)
A liquid crystal solidified layer to be the first optical compensation layer was adhered to the second optical compensation layer obtained above with an isocyanate-based adhesive (thickness 5 μm), and the substrate (norbornene-based resin film) was removed. Then, the laminate 1 in which the first optical compensation layer is transferred to the second optical compensation layer is obtained.
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 2 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 2, the laminate 1 and the polarizing plate are laminated in this order via an acrylic pressure-sensitive adhesive (thickness: 12 μm). At this time, the laminated body 1 is laminated so that the first optical compensation layer is on the polarizing plate side. 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, and the slow axis of the third optical compensation layer is absorbed by the polarizer of the polarizing plate. Lamination is performed so that the angle is 45 ° clockwise with respect to the axis. In this way, the laminated optical film C is produced.

(Production of liquid crystal 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 B. Note that the retardation axis of the polarizer on the backlight side is the reference (0 °), and the slow axis of the second optical compensation layer is 0 ° and the slow axis of the third optical compensation layer is 45 counterclockwise. The layers are laminated so that the slow axis of the fifth optical compensation layer is 135 ° and the absorption axis of the viewing side polarizer is 90 °. In this way, a liquid crystal panel is produced.
Computer simulation was performed on the viewing angle dependence of contrast of a liquid crystal display device using such a liquid crystal panel. The results are shown in FIG.

[Comparative Example 1]
(Preparation of laminated film D)
A laminated film D is produced in the same manner as the laminated optical film B except that the laminated film is laminated so that the slow axis of the second optical compensation layer and the absorption axis of the polarizer of the polarizing plate are orthogonal to each other.

(Production of liquid crystal panel)
A liquid crystal panel is obtained in the same manner as in Example 1 except that the laminated film D is used instead of the laminated optical film B. The slow axis of the second optical compensation layer of the laminated film D is 90 ° counterclockwise with the absorption axis of the polarizer on the backlight side as a reference (0 °), and the third optical of the laminated film D Lamination is performed so that the slow axis of the compensation layer is 45 °, the slow axis of the fifth optical compensation layer of the laminated film A is 135 °, and the absorption axis of the polarizer on the viewing side is 90 °. In this way, a liquid crystal panel is produced.
Computer simulation was performed on the viewing angle dependence of contrast of a liquid crystal display device using such a liquid crystal panel. The results are shown in FIG.

[Comparative Example 2]
(Preparation of laminated film E)
A laminated film E is produced in the same manner as the laminated optical film C, except that the slow axis of the second optical compensation layer and the absorption axis of the polarizer of the polarizing plate are laminated.

(Production of liquid crystal panel)
A liquid crystal panel is obtained in the same manner as in Example 1 except that the laminated film E is used instead of the laminated optical film B. The slow axis of the second optical compensation layer of the laminated film E is 90 ° counterclockwise with the absorption axis of the polarizer on the backlight side as a reference (0 °), and the third optical of the laminated film E Lamination is performed so that the slow axis of the compensation layer is 45 °, the slow axis of the fifth optical compensation layer of the laminated film A is 135 °, and the absorption axis of the polarizer on the viewing side is 90 °. In this way, a liquid crystal panel is produced.
Computer simulation was performed on the viewing angle dependence of contrast of a liquid crystal display device using such a liquid crystal panel. The results are shown in FIG.

  In addition, the whole structure of the panel of Examples 1-2 and Comparative Examples 1-2 is put together in Table 1. The angle (counterclockwise) when the absorption axis of the polarizer on the backlight side is 0 ° is also shown.

  As apparent from FIGS. 4 to 7, the liquid crystal panels of Example 1 and Example 2 of the present invention were superior in contrast to the liquid crystal panels of Comparative Example 1 and Comparative Example 2. 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 laminated optical film, liquid crystal panel, and liquid crystal display device of the present invention can be suitably applied to mobile phones, liquid crystal televisions, and the like.

It is a schematic sectional drawing of the laminated optical film by preferable embodiment of this invention. It is a schematic sectional drawing of the liquid crystal panel by one 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. 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.

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 20 Liquid crystal cell 100 Liquid crystal panel 100' Liquid crystal panel

Claims (7)

A polarizer,
A first optical compensation layer having a refractive index ellipsoid showing a relationship of nz> nx = ny;
A second optical compensation layer in which the refractive index ellipsoid shows a relationship of nx> ny = nz, and the in-plane retardation Re ₂ is 80 to 300 nm;
A refractive index ellipsoid having a relationship of nx>ny> nz, and a third optical compensation layer having an in-plane retardation Re ₃ of 80 to 200 nm, at least in this order,
A laminated optical film, wherein an absorption axis of the polarizer and a slow axis of the second optical compensation layer are parallel.   The fourth optical compensation layer is further provided on the opposite side of the third optical compensation layer from the second optical compensation layer, and the refractive index ellipsoid shows a relationship of nx = ny> nz. The laminated optical film described in 1.   A liquid crystal panel comprising a liquid crystal cell and the laminated optical film according to claim 1.   The liquid crystal panel according to claim 3, wherein the laminated optical film is disposed on a backlight side. A laminated film including a polarizer and a fifth optical compensation layer having a refractive index ellipsoid of nx>ny> nz and an in-plane retardation Re ₅ of 80 to 200 nm is arranged on the viewer side. The liquid crystal panel according to claim 4.   The liquid crystal panel according to claim 3, wherein the liquid crystal cell is in a VA mode.   A liquid crystal display device comprising the liquid crystal panel according to claim 3.