KR20090107938A - Laminated optical film, and liquid crystal panel and liquid crystal display apparatus using the laminated optical film - Google Patents

Abstract

PURPOSE: A laminated optical film, a liquid crystal panel using the same, and a liquid crystal display device are provided to improve screen contrast by arranging a first optical compensation layer and a second optical compensation layer with an optical characteristic. CONSTITUTION: A laminated optical film(10) includes a polarizer(11), a first optical compensation layer(12) and a second optical compensation layer(13). In the first optical compensation layer, a refractive index ellipsoid represents nx>ny>nz. In the second optical compensation layer, the refractive index ellipsoid represents nx>ny>nz. In the third optical compensation layer, the refractive index ellipsoid represents nx>ny>nz or nx>ny=nz. An absorption axis of the polarizer is arranged in the polarizer and the first optical compensation layer to be parallel or vertical to the first optical compensation layer. The absorption axis is arranged in the polarizer and the second optical compensation layer to be parallel or vertical to a ground axis of the second optical compensation layer.

Description

Laminated optical film, and liquid crystal panel and liquid crystal display device using the laminated optical film TECHNICAL FIELD

This application requires 35 U.S.C. Priority is claimed to Japanese Patent Application No. 2008-101440, filed April 9, 2008, under Section 119, which is incorporated herein by reference.

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

Each of the various optical films provided by combining the polarizing film and the optical compensation layer is generally used in an image display device (for example, a liquid crystal display device) to perform optical compensation.

Generally, the circularly polarizing plate which is one kind of above-mentioned optical film can be manufactured combining a polarizing film and (lambda) / 4 plate. However, [lambda] / 4 plates have a property of providing larger phase difference values for short wavelengths, so-called "positive wavelength dispersion characteristics", and λ / 4 plates generally have a high amount of wavelength dispersion characteristics. That is, the λ / 4 plate has a problem in that it cannot exhibit desired optical properties (for example, function as a λ / 4 plate) over a wide range of wavelengths. In order to prevent this problem, recently, retardation plates having wavelength dispersion characteristics, so-called "reverse dispersion characteristics", which provide larger retardation values for long wavelengths, such as modified-cellulose-based films and modified-polycarbonate-based films, have been proposed. have. However, these films have a cost problem.

At present, the following methods are employed: [lambda] / 4 plates having positive wavelength dispersion characteristics are combined with a retardation plate or [lambda] / 2 plates which provide a larger retardation value for longer wavelengths, so that the wavelength dispersion characteristics of the [lambda] / 4 plates are changed. Correction is made (see Japanese Patent No. 3174367, for example). However, the improvement of screen contrast and the reduction of color shift by these techniques are insufficient.

SUMMARY OF THE INVENTION The present invention has been proposed in view of solving the 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 having excellent screen contrast and small color shift.

According to one aspect of the present invention, a laminated optical film is provided. The laminated optical film includes a polarizer; A first optical compensation layer in which the index ellipsoid has a relationship of nx> ny> nz; And a second optical compensation layer in which the index ellipsoid has a relationship of nz> nx> ny, wherein the polarizer and the first optical compensation layer are disposed such that the absorption axis of the polarizer is parallel or perpendicular to the slow axis of the first optical compensation layer. The polarizer and the second optical compensation layer are disposed such that the absorption axis of the polarizer is parallel or perpendicular to the slow axis of the second optical compensation layer.

In one embodiment of the present invention, the Nz coefficient of the second optical compensation layer is -1.0 or less.

In another embodiment of the present invention, the in-plane retardation Re ₂ of the second optical compensation layer satisfies the relationship of 0 nm <Re ₂ ≤ 70 nm.

In another embodiment of the present invention, the laminated optical film further includes a third optical compensation layer in which the index ellipsoid exhibits a relationship of one of nx> ny = nz and nx> ny> nz.

In still another embodiment of the present invention, the in-plane phase difference Re ₃ of the third optical compensation layer is 80 to 200 nm.

In another embodiment of the present invention, the laminated optical film further includes a fourth optical compensation layer in which the index ellipsoid has a relationship of nx = ny> nz.

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

In one embodiment of the present invention, the liquid crystal cell is in VA mode.

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

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

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated by preferable embodiment, this invention is not limited to this.

(Term and Sign Definition)

Terms and symbols used in the present specification are as follows.

(1) refractive index (nx, ny, nz)

"nx" represents the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), "ny" represents the refractive index in the direction perpendicular to the in-plane slow axis (ie, the fast axis direction), and "nz" Represents the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

In-plane retardation Re refers to an in-plane retardation of a layer (film) at a wavelength of 590 nm at 23 ° C. unless otherwise stated. Re is obtained by Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). In the present specification, Re (550) refers to an in-plane retardation of a layer (film) at a wavelength of 550 nm. In addition, the subscript "1" denoted by the term or symbol described herein denotes the first optical compensation layer, and the subscript "2" denotes the second optical compensation layer. For example, the in-plane retardation of the first optical compensation layer is represented by Re ₁ .

(3) thickness direction retardation (Rth)

Thickness direction retardation (Rth) means the phase difference in the thickness direction of a layer (film) at 23 degreeC wavelength 590 nm unless otherwise stated. Rth is calculated as Rth = (nx-nz) x d, where d (nm) is the thickness of the layer (film). In the present specification, Rth 550 refers to a thickness direction retardation of a layer (film) at a wavelength of 550 nm. Also, for example, in the present specification indicates a first thickness direction retardation Rth of the optical compensation layer to the _first.

(4) Nz coefficient

The Nz coefficient is obtained by Nz = Rth / Re.

(5) λ / 4 plate

"λ / 4 plate" is an electro-optical birefringent plate and has a function of generating an optical path difference of 1/4 wavelength between linearly polarized beams oscillating in directions perpendicular to each other.

A. Laminated Optical Film

A-1. Overall composition of laminated optical film

1A 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. 1B is a schematic cross-sectional view of a laminated optical film according to another 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 disposed on one side of the polarizer 11. And a fourth optical compensation layer 15. The stacking order of each optical compensation layer is not particularly limited and any suitable order may be adopted. Preferably, as in the example shown, the polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer and the fourth optical compensation layer are stacked in the order mentioned.

Although not shown in FIGS. 1A and 1B, if necessary, the laminated optical film of the present invention includes a first protective layer between the polarizer 11 and the optical compensation layer, and the polarizer 11 side with no optical compensation layer disposed thereon. And a second protective layer. When the first protective layer is not provided, the first optical compensation layer 12 can also function as a protective layer of the polarizer 11. The first optical compensation layer functions as a protective layer, thereby contributing to the reduction in the thickness of the laminated optical film (liquid crystal panel). In addition, the laminated optical film of the present invention further includes any suitable optical compensation layer if necessary.

The refractive index ellipsoid of the first optical compensation layer 12 is nx> ny> nz. The first optical compensation layer 12 is formed such that the slow axis forms any suitable angle with respect to the absorption axis of the polarizer 11, depending on the purpose, the configuration of the liquid crystal panel to which the first optical compensation layer 12 is applied, and the like. Is placed. Preferably, the polarizer 11 and the first optical compensation layer 12 are arranged such that their absorption axis and slow axis are parallel or perpendicular to each other. More preferably, the polarizer and the first optical compensation layer are arranged such that their absorption axis and slow axis are perpendicular to each other. The polarizer 11 and the first optical compensation layer 12 are disposed with this positional relationship, thereby obtaining a liquid crystal panel with improved screen contrast and reduced color shift. As used herein, the term "parallel" also includes cases that are substantially parallel. Here, the phrase “substantially parallel” includes the case of 0 ° ± 3.0 °, preferably 0 ° ± 1.0 °, more preferably 0 ° ± 0.5 °. As used herein, the term "vertical" includes the case of being substantially vertical. The phrase “substantially vertical” here includes cases where 90 ° ± 3.0 °, preferably 90 ° ± 1.0 °, more preferably 90 ° ± 0.5 °.

The second optical compensation layer 13 has an index ellipsoid of nz> nx> ny. The second optical compensation layer 13 is disposed such that the slow axis forms any suitable angle with respect to the absorption axis of the polarizer 11, depending on the purpose, the configuration of the liquid crystal panel, and the like. Preferably, the polarizer 11 and the second optical compensation layer 13 are arranged such that their absorption axis and slow axis are parallel or perpendicular to each other. More preferably, the polarizer and the second optical compensation layer are arranged such that their absorption axis and slow axis are perpendicular to each other. The polarizer 11 and the second optical compensation layer 13 are arranged with this positional relationship, whereby a liquid crystal panel with improved screen contrast and reduced color shift is obtained.

The third optical compensation layer 14 has an index ellipsoid of nx> ny = nz or nx> ny> nz. The third optical compensation layer 14 is arranged such that the slow axis forms any suitable angle with respect to the absorption axis of the polarizer 11, depending on the purpose, the configuration of the liquid crystal panel, and the like. Specifically, the slow axis of the third optical compensation layer 14 is preferably 30 ° to 60 °, more preferably 35 ° to 55 °, even more preferably 40 ° to the absorption axis of the polarizer 11. It is arranged to form an angle of 50 degrees, particularly preferably 43 degrees to 47 degrees, most preferably about 45 degrees. The polarizer 11 and the third optical compensation layer 14 are disposed with this positional relationship, thereby obtaining a liquid crystal panel with improved screen contrast and reduced color shift.

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

A-2. First optical compensation layer

The first optical compensation layer has a relation that the refractive index ellipsoid is nx>ny> nz. The in-plane retardation Re ₁ of the first optical compensation layer is preferably 80 to 200 nm, more preferably 80 to 150 nm, even more preferably 80 to 130 nm. The Nz coefficient (Rth ₁ / Re ₁ ) preferably has a relationship of 1 <Nz <2, more preferably 1 <Nz <1.5. By providing the first optical compensation layer having such an optical characteristic, the absorption axis of the polarizer can be compensated preferably, and the screen contrast of the liquid crystal panel can be improved. In addition, color shift can be reduced.

The first optical compensation layer can be formed of any suitable material. Specifically, the stretched film of the polymer film is a specific example of the material. The resin forming the polymer film is preferably norbornene-based resin or polycarbonate-based resin.

The norbornene-based resin is obtained by polymerizing a norbornene-based monomer as a polymerization unit. Examples of norbornene-based monomers include norbornene and its alkyl and / or alkylidene-substituted monomers such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5 Substituted monomers in which butyl-2-norbornene, 5-ethylidene-2-norbornene and norbornene and their alkyl and / or alkylidene-substituted monomers are substituted with a polar group such as halogen; Dicyclopentadiene, 2,3-dihydrodicyclopentadiene and the like; Substituted monomers substituted with dimethanooctahydronaphthalene, alkyl and / or alkylidene and substituted monomers substituted with a polar group 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 -Octahydronaphthalene, 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-octahydro Naphthalene and 6-methoxycarbonyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene; And trimers or tetramers of cyclopentadiene, such as 4,9: 5,8-dimethano-3a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene, or 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentaanthracene Include. 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. Aromatic polycarbonates can typically be obtained by reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of carbonate precursors include phosgene, bischloroformates of dihydric phenols, diphenyl carbonate, di-p-tolylcarbonate, phenyl-p-tolylcarbonate, di-p-chlorophenylcarbonate and dinaphthylcarbonate . Among them, 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; 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; And 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. These can be used individually or in mixture. Preferred are 2,2-bis (4-hydroxyphenyl) propane; 1,1-bis (4-hydroxyphenyl) cyclohexane; And 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. In particular, it is preferable to use a mixture of 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

The polymer film may contain any other suitable thermoplastic resin. Examples of other thermoplastic resins are general-purpose plastics such as polyolefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile / butadiene / styrene resins, acrylonitrile / styrene resins, polymethyl methacryl Latex, polyvinyl acetate and polyvinylidene chloride resins; General-purpose engineering plastics such as polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin and polyethylene terephthalate resin; And super engineering plastics such as polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyether ether ketone resin, polyarylate resin, liquid crystalline resin, polyamide-imide resin, poly Mid type resin and polytetrafluoroethylene type resin are included.

Arbitrary suitable methods can be employ | adopted as a manufacturing method of a stretched film. Examples of the stretching method include transverse uniaxial stretching, free end uniaxial stretching, fixed end biaxial stretching, fixed end uniaxial stretching, and sequential biaxial stretching. Specific examples of the fixed end biaxial stretching include a method of stretching the polymer film in a unidirectional (lateral direction) while running the polymer film in the longitudinal direction. This method may be a lateral uniaxial stretching method in appearance. These stretching methods may be adopted alone or in combination of at least two methods. For example, after performing free end uniaxial stretching, fixed end uniaxial stretching is performed. Stretching temperature becomes like this. Preferably it is 135-165 degreeC, More preferably, it is 140-160 degreeC. The stretching ratio is preferably 1.2 to 3.2 times, more preferably 1.3 to 3.1 times. In this case, thickness is 20-80 micrometers normally, Preferably it is 25-75 micrometers, More preferably, it is 30-60 micrometers.

Another embodiment of forming the first optical compensation layer includes a non-liquid crystalline material. The non-liquid crystalline material is preferably a non-liquid crystalline polymer. Specifically, polymers such as polyamide, polyimide, polyester, polyether ketone, polyamideimide and polyesterimide are preferred. These polymers can be used alone or as a mixture of at least two kinds. Among them, polyimides are particularly preferred because of their high transparency, high orientation and high stretchability.

The first optical compensation layer can be conventionally formed by applying a non-liquid crystalline polymer solution to the base film and removing the solvent. In the formation method of an optical compensation layer, the process (for example, extending | stretching process) which preferably gives optical biaxiality (nx> ny> nz) is performed. This treatment can certainly provide an in-plane refractive index difference (nx> ny). Specific examples of the polyimide and specific methods of forming the optical compensation layer are described in Japanese Patent Laid-Open No. Methods for producing the polymer and optical compensation films described in 2004-46065. In this case, the thickness of the first optical compensation layer is usually 0.1 to 10 m, preferably 0.1 to 8 m, even more preferably 0.1 to 5 m.

A-3. Second optical compensation layer

In the second optical compensation layer, the index ellipsoid has a relationship of nz> nx> ny. The layer (film) having such an index ellipsoid may be referred to as a "positive biaxial plate" or the like.

The in-plane retardation Re ₂ of the second optical compensation layer is preferably 0 nm <Re ₂ ≤70 nm, more preferably 0 nm <Re ₂ ≤60 nm, even more preferably 0 nm <Re ₂ ≤50 nm, particularly preferably The relationship of 10 nm <Re ₂ <50 nm is satisfied. The thickness direction retardation Rth ₂ of the second optical compensation layer is preferably -200 to -50 nm, more preferably -100 to -50 nm, 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, 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 compensated in a preferred manner, and the screen contrast of the liquid crystal panel can be improved. In addition, color shift can be reduced.

The second optical compensation layer can have any suitable configuration. Specifically, the second optical compensation layer may be formed only of the retardation film, or may be a laminate of at least two identical or different retardation films. When the second optical compensation layer is a laminate, the second optical compensation layer may include an adhesive layer or an adhesive layer to attach at least two retardation films. The second optical compensation layer is preferably a single retardation film. By adopting such a configuration, it is possible to reduce variation and unevenness of the retardation value caused by the shrinkage stress of the polarizer and the heat of the light source. This configuration can also contribute to the reduction in the thickness of the liquid crystal panel obtained.

The optical properties of the retardation film may be set to any suitable value depending on the configuration of the second optical compensation layer. For example, when the second optical compensation layer is a single retardation film, it is preferable that the optical properties of the retardation film are set equal to the optical properties of the second optical compensation layer. That is, it is preferable that the phase difference values of an adhesive layer, an adhesive bond layer, etc. used in order to laminate | stack a phase difference film on a polarizer 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, particularly preferably 30 to 300 µm. When the thickness of the second optical compensation layer is within this range, the handleability during manufacturing becomes excellent, and the optical uniformity of the obtained liquid crystal display device (liquid crystal panel) can be improved.

As the retardation film, it is preferable to use a film that is excellent in transparency, mechanical strength, thermal stability, water repellency, and the like and that optical irregularity due to distortion is unlikely to occur. As the retardation film, it is preferable to use a stretched polymer film mainly containing a thermoplastic resin. As the thermoplastic resin, it is preferable that a polymer exhibiting negative birefringence is 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, the expression "indicating negative birefringence" means that the refractive index in the stretching direction becomes relatively small when the polymer is aligned by stretching or the like; That is, it means that the refractive index in the direction perpendicular to the stretching direction rises. Examples of polymers exhibiting negative birefringence include polymers in which chemical bonds or functional groups having large polarization anisotropy are introduced into the side chain, such as aromatic rings and carbonyl groups. Specifically, examples of such polymers include acrylic resins, styrene resins and maleimide resins.

An acrylic resin can be obtained by addition polymerization process of an acrylate-type monomer, for example. Examples of acrylic resins include polymethyl methacrylate (PMMA), polybutyl methacrylate and polycyclohexyl methacrylate.

Styrene-type resin can be obtained by addition polymerization process of a styrene-type monomer, for example. Examples of styrene-based monomers include styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenyl styrene, 2, 5-dichlorostyrene and pt-butyl styrene.

Maleimide-type resin can be obtained by addition polymerization process of a maleimide-type monomer, for example. Examples of maleimide monomers include N-ethyl maleimide, N-cyclohexyl maleimide, N-phenyl maleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, 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 and N- (2-cyanophenyl) maleimide It includes. Maleimide monomers are available from Tokyo Chemical Industry Co., Ltd. Available from the back and the like.

In addition polymerization, the birefringence characteristic of the obtained resin can also be controlled by subjecting side chains to substitution, maleimation, or graft reaction after polymerization.

The polymer exhibiting negative birefringence may be a polymer copolymerized with another monomer. Brittleness, molding processability and heat resistance can be improved by copolymerization with another monomer. Examples of further monomers include olefins such as ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene and 1-hexene; Acrylonitrile; (Meth) acrylates such as methyl acrylate and methyl methacrylate; Maleic anhydride; And vinyl esters such as vinyl acetate.

When the polymer showing negative birefringence is a copolymer of a styrene monomer and another monomer, the blending ratio of the styrene monomer is preferably 50 to 80 mol%. When the polymer showing negative birefringence is a copolymer of a maleimide monomer and another monomer, the blending ratio of the maleimide monomer is preferably 2 to 50 mol%. By mix | blending a monomer in this range, the polymer film excellent in tenacity and moldability can be obtained.

As the polymer exhibiting negative birefringence, preferably, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene- (meth) acrylate copolymer, styrene-maleimide copolymer, vinyl ester-maleimide co Polymers, olefin-maleimide copolymers and the like are used. These polymers may be used alone or in combination. These polymers exhibit high negative birefringence and may be excellent in heat resistance. These polymers are described, for example, in Nova Chemicals Japan Ltd., Arakawa Chemical Industries, Ltd. Available from the back and the like.

As a polymer which shows negative birefringence, Preferably, the polymer which has a repeating unit represented by following General formula (I) is also used. Such polymers exhibit higher negative birefringence and may be superior in heat resistance and mechanical strength. Such a polymer can be obtained using, for example, N-phenyl substituted maleimide in which a phenyl group having at least a substituent at the ortho-position is introduced as the N-substituent of the maleimide monomer of the raw material.

Formula 1

In General Formula (I), each of R ₁ to R ₅ independently represents a hydrogen atom, a halogen atom, a carboxylic acid, a carboxylic acid ester, a hydroxyl group, a nitro group, or a linear or branched carbon atom having 1 to 8 carbon atoms. Phosphorus alkyl group or alkoxy group, provided that R ₁ and R ₅ are not hydrogen atoms at the same time; R ₆ and R ₇ represent a hydrogen atom or an alkyl or alkoxy group having 1 to 8 carbon atoms in a straight or branched chain; And n represents an integer of 2 or more.

The polymer which shows negative birefringence is not limited to the above, For example, Unexamined-Japanese-Patent No. Cyclic olefin copolymers disclosed in 2005-350544 and the like can also be used. In addition, Japanese Patent Laid-Open No. 2005-156862, Japanese Patent Laid-Open No. The composition containing the polymer and inorganic fine particles disclosed by 2005-227427 etc. can also be used preferably. As a polymer which shows negative birefringence, you may use individually by 1 type or mix before using at least 2 types. In addition, these polymers may be modified by copolymerization, branching, crosslinking, molecular terminal modification (or encapsulation), stereoregular modification, or the like before use.

The polymer film may further contain any suitable additive as necessary. Specific examples of the additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, UV absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinkers and thickeners. The type and content of the additive to be used may be appropriately set according to the purpose. The content of the additive is approximately 3 to 10 parts by weight based on 100 parts by weight of the total solids of the polymer film. If the content of the additive is too high, the transparency of the polymer film may be lowered, or the additive may bleed out from the polymer film surface.

Any suitable molding method can be employed as the molding direction of the polymer film. Examples of suitable molding methods include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, solvent casting, and the like. Among them, extrusion molding or solvent casting is preferable because a high smoothness retardation film having good optical uniformity can be obtained. Specifically, extrusion molding includes melting a resin composition containing a thermoplastic resin, a plasticizer, an additive, and the like under heating; Extruding the molten resin composition into a thin film on the surface of the casting roller using a T-die or the like; And cooling the whole to form a film. Solvent casting comprises the steps of defoaming the concentrated solution (dope) prepared by dissolving the resin composition in a solvent; Uniformly casting the defoamed solution into a thin film on a surface of a metallic endless belt or rotating drum, plastic substrate, or the like; And evaporating the solvent to form a film. Molding conditions can be appropriately set according to the kind of composition or resin used, a molding method, and the like.

The retardation film (stretched film) can be obtained by stretching the polymer film under any suitable stretching conditions. Specific examples of the stretching method include longitudinal uniaxial stretching, transverse uniaxial stretching, longitudinal transverse biaxial stretching, and transverse simultaneous biaxial stretching. Preferably, the transverse uniaxial stretching method, the transverse sequential biaxial stretching method, and the transverse simultaneous biaxial stretching method are used. This is because a biaxial retardation film can be obtained in a preferred manner. In polymers exhibiting negative birefringence, the refractive index in the stretching direction becomes relatively small as described above. Therefore, in the case of the transverse uniaxial stretching method, the slow axis is provided in the transport direction of the polymer film (the refractive index in the transport direction is nx). In the case of the longitudinal sequential biaxial stretching method and the longitudinal lateral simultaneous biaxial stretching method, any of the transport direction and the width direction may be set as the slow axis in accordance with the ratio of the longitudinal and horizontal draw ratios. Specifically, when the draw ratio in the longitudinal (transport) direction is relatively large, the transverse (width) direction is the slow axis, and when the draw ratio in the transverse (width) direction is relatively large, the longitudinal (transport) direction is It becomes the slow axis.

As the stretching apparatus used for the stretching, any suitable stretching apparatus can be used. Specific examples include roll stretching machines, tenter stretching machines and fantagraph type or linear motor type biaxial stretching machines. In thermal stretching, the stretching temperature can be changed continuously or can be changed step by step. Stretching can be carried out in two or more stages.

The stretching temperature (temperature in the stretching oven when the polymer film is stretched) is preferably in the vicinity of the glass transition temperature (Tg) of the polymer film. Specifically, the stretching temperature is preferably (Tg-10) ° C to (Tg + 30) ° C, more preferably Tg to (Tg + 25) ° C, particularly preferably (Tg + 5) ° C to (Tg + 20) ° C. to be. If the stretching temperature is too low, the retardation value and slow axis direction may become uneven, and the polymer film may crystallize (cloudy). On the other hand, when the stretching temperature is too high, the polymer film may be melted, and retardation expression may become insufficient. Stretching temperature is 110-200 degreeC normally. The glass transition temperature can be obtained by the DSC method in accordance with JISK7121-1987.

As a temperature control method in a stretching oven, any suitable method can be adopted. Examples include air circulation constant temperature ovens in which hot or cold air circulates, heaters using microwaves, infrared rays, and the like, heated rolls, heat pipe rolls, metal belts and the like for temperature control.

The draw ratio at the time of stretching the polymer film may be set to any suitable value according to the composition of the polymer film, the kind of volatile components and the like, the residual amount of the volatile components and the like, the desired retardation value and the like. The draw ratio is preferably 1.05 to 5.00 times. In addition, the feed rate during the stretching is preferably 0.5 to 20 m / min in terms of mechanical precision, stability, and the like of the stretching apparatus.

Thus, a method of obtaining a retardation film using a polymer exhibiting negative birefringence has been described. Retardation films can also be obtained using polymers that exhibit positive birefringence. As a method of obtaining a retardation film using the polymer which shows a positive birefringence, For example, Unexamined-Japanese-Patent No. 2000-231016, Japanese Patent Laid-Open No. 2000-206328, Japanese Patent Laid-Open No. As disclosed in 2002-207123 and the like, a stretching method of increasing the refractive index in the thickness direction can be used. Embodiments include a method of attaching and heat treating a heat shrinkable film to one or both surfaces of a film comprising a polymer exhibiting a positive refractive index. The film is shrunk in the longitudinal direction and the width direction under the action of the shrinkage force of the heat shrinkable film by heat treatment, so that the refractive index in the thickness direction can be increased and a retardation film having an index ellipsoid of nz> nx> ny can be obtained.

As described above, the positive biaxial plate used in the second optical compensation layer can be manufactured using a polymer exhibiting positive or negative birefringence. In general, the use of polymers exhibiting positive birefringence is advantageous in that there are many kinds of polymers to choose from. The use of a polymer exhibiting negative birefringence is advantageous in that a retardation film having excellent uniformity in the slow axis direction is more easily obtained by the stretching method as compared with the case of using a polymer exhibiting positive birefringence.

As a retardation film used for a 2nd optical compensation layer, a commercially available optical film can be used as it is instead of the film mentioned above. Moreover, after performing secondary processing, such as extending | stretching and / or relaxation, you may use a commercially available optical film.

The light transmittance of the retardation film at a wavelength of 590 nm is preferably 80% or more, more preferably 85% or more, particularly preferably 90% or more. The theoretical upper limit of the light transmittance is 100%, but since the surface reflection is caused by the refractive index difference between the air and the retardation film, the upper limit of the light transmittance that can be realized is about 94%. As a whole of the second optical compensation layer, similar light transmittance is preferable.

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, more preferably 3.0 × 10 ^-11 (m 2 / N) ), Particularly preferably 1.0 × 10 ⁻¹¹ (m 2 / N) or less. By setting the photoelastic coefficient in this range, it is possible to obtain a liquid crystal display device (liquid crystal panel) which is excellent in optical uniformity and durability and has a smaller change in optical properties even in an environment such as high temperature and high humidity. The lower limit of the photoelastic coefficient is not particularly limited, but the lower limit is generally 5.0 × 10 ⁻¹³ (m 2 / N) or more, preferably 1.0 × 10 ⁻¹² (m 2 / N) or more. When the photoelastic coefficient is too small, the reproducibility of the phase difference can be reduced. The photoelastic coefficient is a value unique to chemical structures such as polymers, but the photoelastic coefficient can be reduced by copolymerizing or mixing a plurality of components having photoelastic coefficients having different signs (positive / negative).

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

A-4. Third optical compensation layer

The laminated optical film of the present invention may further include a third optical compensation layer as described above. The third optical compensation layer can function as a so-called λ / 4 plate. The third optical compensation layer is, for example, a? / 4 plate, which can convert linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). The third optical compensation layer can mainly compensate for 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, even more preferably 110 to 155 nm, particularly preferably 130 to 150 nm.

A-4-1. Third Optical Compensation Layer (1)

In one embodiment, the third optical compensation layer has an index ellipsoid of nx> ny = nz. Here, "ny = nz" includes not only the case where ny and nz are strictly identical to each other, but also the case where ny and nz are substantially identical to each other. More specifically, "ny = nz" refers to the case where the Nz coefficient (Rth ₃ / Re ₃ ) is greater than 0.9 and less than 1.1.

As a material for forming a third optical compensation layer having an index ellipsoid of nx> ny = nz, any suitable material can be adopted as long as the above properties can be obtained. A liquid crystal material is preferable, and a liquid crystal material (nematic liquid crystal) having a nematic phase liquid crystal phase is more preferable. By using the liquid crystal material, the difference between nx and ny of the optical compensation layer obtained can be significantly increased compared to the non-liquid crystal material. As a result, the thickness of the optical compensation layer for obtaining the desired in-plane retardation can be significantly reduced, which can contribute to the reduction in the thickness of the liquid crystal panel and the laminated optical film obtained. As such a liquid crystal material, a liquid crystal polymer and a liquid crystal monomer can be used, for example. The liquid crystalline expression mechanism of the liquid crystal material may be a lyotropic type or a thermotropic type. 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, respectively.

When a liquid crystal material is a liquid crystalline monomer, it is preferable that a liquid crystalline monomer is a polymerizable monomer and / or a crosslinkable monomer, for example. This is because the alignment state of the liquid crystalline monomer can be fixed by polymerizing or crosslinking the liquid crystalline monomer. When the liquid crystalline monomers are oriented and then polymerized or crosslinked with each other, for example, the alignment state can be fixed. The polymer is formed by polymerization and the three-dimensional network structure is formed by crosslinking, all of which are non-liquid crystalline. Thereby, in the formed 3rd optical compensation layer, phase transition between a liquid crystal phase, a glass phase, and a crystalline phase does not generate | occur | produce, for example due to the temperature change inherent in a liquid crystalline compound. As a result, the formed third optical compensation layer can be an optical compensation layer with remarkably excellent stability, which is not affected by temperature change.

The specific example of a liquid crystal monomer and the formation method of a 3rd optical compensation layer are described in Unexamined-Japanese-Patent No. Monomers and formation methods described in 2006-178389.

The thickness of the third optical compensation layer can be set to function most appropriately as the λ / 4 plate. That is, the thickness can be set to obtain a desired optical characteristic. When the third optical compensation layer is formed of a liquid crystal material, the thickness is preferably 0.5 to 10 m, more preferably 0.5 to 8 m, even more preferably 0.5 to 5 m.

Further, the third optical compensation layer having an index ellipsoid of nx> ny = nz can be formed by stretching the polymer film. Specifically, the third optical compensation layer having desired optical properties (e.g., refractive index ellipsoid, in-plane retardation, thickness direction retardation) may include a polymer type, stretching conditions (e.g., stretching temperature, stretching ratio, stretching direction), It can be obtained by appropriately selecting the stretching method or the like. More specifically, extending | stretching temperature becomes like this. Preferably it is 110-170 degreeC, More preferably, it is 130-150 degreeC. 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 a transverse uniaxial stretching method.

When extending | stretching a polymer film and forming a 3rd optical compensation layer, the thickness becomes like this. Preferably it is 5-55 micrometers, More preferably, it is 10-50 micrometers, More preferably, it is 15-45 micrometers.

Arbitrary suitable resin can be employ | adopted as resin which forms a polymer film. Specific examples thereof include resins constituting positive birefringent films such as norbornene-based resins, polycarbonate-based resins, cellulose-based resins, polyvinyl alcohol-based resins, and polysulfone-based resins. Among them, norbornene-based resins and polycarbonate-based resins are preferable. The details of these resins are as described above in section A-2.

A-4-2. Third Optical Compensation Layer (2)

In another embodiment, the third optical compensation layer has an 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.

As the material and method for forming the third optical compensation layer whose refractive index ellipsoid is nx> ny> nz, the same material and method as the first optical compensation layer can be employed.

A-5. Fourth optical compensation layer

The laminated optical film of the present invention may further include a fourth optical compensation layer as described above. In the fourth optical compensation layer, the index ellipsoid has a relationship of nx = ny> nz. Here, "nx = ny" includes not only the case where nx and ny are strictly identical to each other, but also the case where nx and ny are substantially identical to each other. Specifically, "nx = ny" refers to the case where Re ₄ is less than 10 nm. The thickness direction retardation Rth ₄ of the fourth optical compensation layer can be set to any suitable value depending on the configuration of the liquid crystal panel to which the fourth optical compensation layer is applied. The details are described later in section B-5. The fourth optical compensation layer can mainly compensate for the liquid crystal cell.

The fourth optical compensation layer can be formed of any suitable material as long as the above properties can be obtained. Embodiments of the fourth optical compensation layer include a cholesteric alignment pinned layer. The term “cholesteric alignment fixed layer” refers to a layer in which the constituent molecules of the layer constitute a helical structure, the helical axis of which is oriented substantially perpendicular to the plane direction, and whose orientation state is fixed. That is, the "cholesteric alignment fixed 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 crystalline compound forms a pseudo structure as in the cholesteric liquid crystal phase. For example, a "cholesteric alignment fixed layer" is used to orientate a liquid crystal material in a cholesteric structure (helical structure) by providing a distortion to the liquid crystal material using a chiral agent while the liquid crystal material exhibits a liquid crystal phase. And it can form by polymerizing or crosslinking-processing the liquid crystal material of an orientation state, and fixing the orientation (cholesteric structure) of a liquid crystal material.

Specific examples of the cholesteric alignment pinned layer are described in Japanese Patent Laid-Open No. Cholesteric layer described in 2003-287623.

The thickness of the fourth optical compensation layer can be set to any suitable value as long as the desired optical properties described below can be obtained. When the fourth optical compensation layer is a cholesteric alignment fixed layer, the thickness of the fourth optical compensation layer is preferably 0.5 to 10 m, more preferably 0.5 to 8 m, even more preferably 0.5 to 5 m.

Another embodiment of the material forming the fourth optical compensation layer includes a non-liquid crystalline material. Particular preference is given to non-liquid crystalline polymers. Unlike the liquid crystalline material, such non-liquid crystalline material can form a film exhibiting optical uniaxiality of nx = ny> nz due to its nature, regardless of the orientation of the substrate. As non-liquid crystalline materials, for example, polymers such as polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide are preferred because of their excellent heat resistance, chemical resistance, transparency and excellent rigidity. Any one kind of these polymers may be used alone or as a mixture of at least two kinds having different functional groups, such as a mixture of polyaryl ether ketones and polyamides. Among these polymers, polyimides are particularly preferred because of their high transparency, high orientation and high stretchability.

As a specific example of a polyimide and a specific example of a method for forming a fourth optical compensation layer, Japanese Patent Laid-Open No. There is a method for producing the polymer and optical compensation film described in 2004-46065.

The thickness of the fourth optical compensation layer can be set to any suitable value as long as the desired optical characteristics described below can be obtained. When the fourth optical compensation layer is formed of a non-liquid crystalline material, the thickness of the fourth optical compensation layer is preferably 0.5 to 10 m, more preferably 0.5 to 8 m, even more preferably 0.5 to 5 m.

Another embodiment of the material for forming the fourth optical compensation layer includes a polymer film formed of cellulose resin such as triacetyl cellulose (TAC), norbornene-based resin, or the like. As a 4th optical compensation layer, a commercially available film can be used as it is. In addition, secondary treatments, such as stretching and / or shrinkage treatments, may be performed on commercially available films prior to use. Examples of commercially available films are Fuji Photo Film Co., Ltd. FujiTak series of manufacture (ZRF80S, TD80UF, TDY-80UL), "KC8UX2M" (trade name) manufactured by Konica Minolta Opt Product, "Zeonor" (trade name) manufactured by Zeon, "Arton" manufactured by JSR Brand name). The norbornene-based monomer constituting the norbornene-based resin is as described above in Section A-2. As an extending | stretching method which can satisfy an optical characteristic, there exists predetermined biaxial stretching (horizontal and equal ratio magnification stretching), for example.

The thickness of the fourth optical compensation layer can be set to any suitable value as long as the desired optical characteristics described below can be obtained. When the fourth optical compensation layer is a polymer film formed of cellulose resin, norbornene resin, or the like, the thickness of the fourth optical compensation layer is preferably 45 to 105 µm, more preferably 55 to 95 µm, even more preferably 50 It is -90 micrometers.

Another embodiment of the fourth optical compensation layer includes a laminate having a cholesteric alignment pinned layer and a plastic film layer. Examples of the resin forming the plastic film layer include cellulosic resins and norbornene-based resins. These resins are as described above in this section.

Arbitrary suitable methods can be employ | adopted as a lamination method of a cholesteric orientation fixed layer and a plastic film layer. Specifically, there is a method of transferring the cholesteric alignment fixing layer onto the plastic layer, a method of attaching the cholesteric alignment fixing layer previously formed on the substrate to the plastic film layer through an adhesive layer or the like. As the adhesive for forming the adhesive layer, there is usually a curable adhesive. Representative examples of curable adhesives include photocurable adhesives, such as UV-curable types, moisture-curable adhesives and thermosetting adhesives. The thickness of the adhesive layer is preferably 1 µm to 10 µm, more preferably 1 µm to 5 µm.

A-6. Polarizer

Any suitable polarizer may be employed as the polarizer depending on the purpose. Examples include dichroic substances such as iodine or dichroic dyes in hydrophilic polymer films such as polyvinyl alcohol films, partially foamed polyvinyl alcohol films, or partially saponified ethylene / vinyl acetate copolymer films. A film prepared by absorbing and uniaxially stretching the film; And polyene-based alignment films such as dewatered products of polyvinyl alcohol-based films or desalted products of polyvinyl chloride-based films. Among them, a polarizer produced by absorbing a dichroic substance such as iodine on a polyvinyl alcohol-based film and uniaxially stretching the film is particularly preferable because of its high polarization dichroic ratio. Although the thickness of a polarizer is not specifically limited, Generally, it is about 1-80 micrometers.

A polarizer prepared by absorbing iodine in a polyvinyl alcohol-based film and uniaxially stretching the film may include, for example, immersing the polyvinyl alcohol-based film in an aqueous iodine solution for coloring; And stretching the film to a length 3 to 7 times the original length. The aqueous solution may contain boric acid, zinc sulfate, zinc chloride, or the like as necessary, or the polyvinyl alcohol-based film may be dipped in an aqueous solution of potassium iodide or the like. Also, if desired, the polyvinyl alcohol-based film may be immersed and washed in water before coloring.

The water washing of the polyvinyl alcohol-based film not only removes contaminants on the film surface or washes off the antiblocking agent, but also provides an effect of preventing nonuniformity such as uneven coloring by swelling the polyvinyl alcohol-based film. Stretching of the film can be carried out after coloring the film with iodine, during the coloring of the film, or before coloring the film with iodine. Stretching can be carried out in an aqueous solution of potassium iodide or boric acid or in a water bath.

A-7. Protective layer

The first protective layer and the second protective layer are formed of any suitable film that can be used as a protective layer for polarizer. Specific examples of the material used as the main component of the film include transparent resins such as cellulose resins such as triacetyl cellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, and poly Mid resin, polyether sulfone resin, polysulfone resin, polystyrene resin, polynorbornene resin, polyolefin resin, (meth) acrylic resin and acetate resin. Still other examples include thermosetting resins or UV-curing resins such as (meth) acrylic resins, urethane resins, (meth) acrylic urethane resins, epoxy resins, or silicone resins. Still other examples include glassy polymers such as, for example, siloxane based polymers. Moreover, the polymer film described in JP 2001-343529 A (WO 01/37007) can also be used. Specifically, the film may be formed of 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 a nitrile group in the side chain. Specific examples include a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded molding of the resin composition.

Glass transition temperature (Tg) of a (meth) acrylic resin 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, Especially preferably, it is 130 degreeC or more. This is because the (meth) acrylic resin having a glass transition temperature (Tg) of 115 ° C or higher may be excellent in durability. Although the upper limit of Tg of (meth) acrylic resin is not specifically limited, From a viewpoint of moldability etc., it is preferably 170 degrees C or less.

As (meth) acrylic resin, arbitrary appropriate (meth) acrylic resin can be employ | adopted, unless the effect of this invention is impaired. Examples of (meth) acrylic resins include poly (meth) acrylates such as methyl polymethacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylate copolymers, methyl methacrylate Latex-acrylate- (meth) acrylic acid copolymers, methyl (meth) acrylate-styrene copolymers (such as MS resins) and polymers having alicyclic hydrocarbon groups (eg, methyl methacrylate-cyclohexyl methacrylate co) Polymer, methyl methacrylate-novonyl (meth) acrylate copolymer). Preferred examples include C _1-6 alkyl poly (meth) acrylic acids such as polymethyl (meth) acrylate. More preferred examples include methyl methacrylate resins containing methyl methacrylate as the main component (50 to 100% by weight, preferably 70 to 100% by weight).

A specific example of the (meth) acrylic resin is Mitsubishi Rayon Co., Ltd. It includes a (meth) acrylic resin having a ring structure in the molecule described in ACRYPET VH and ACRYPET VRL20A, JP 2004-70296 A, high molecular weight (meth) acrylic resin obtained by intramolecular crosslinking or intramolecular circulation reaction. .

As said (meth) acrylic resin, the (meth) acrylic resin which has a lactone ring structure is especially preferable because of high heat resistance, high transparency, and high mechanical strength.

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

The mass average molecular weight (also referred to as weight average molecular weight) of the (meth) acrylic resin having a lactone ring structure is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, even more preferably 10,000 to 500,000, particularly preferably 50,000 500,000.

The glass transition temperature (Tg) of the (meth) acrylic resin having a lactone ring structure is preferably 115 ° C or higher, more preferably 125 ° C or higher, even more preferably 130 ° C or higher, particularly preferably 135 ° C or higher, most preferably 140 It is more than ℃. This is because the (meth) acrylic resin which has a lactone ring structure and whose Tg is 115 degreeC or more may be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin which has a lactone ring structure is not specifically limited, From a viewpoint of moldability etc., it is preferably 170 degrees C or less.

As used herein, the term "(meth) acryl" refers to acrylic and / or methacryl.

The first protective layer and the second protective layer are preferably transparent colorless. The thickness direction retardation Rth of the second protective layer is preferably -90 nm to +90 nm, more preferably -80 nm to +80 nm, even more preferably -70 nm to +70 nm.

As the thickness of the first protective layer and the second protective layer, any suitable thickness can be adopted as long as the preferred thickness direction retardation Rth can be obtained. The thickness of a 2nd protective layer is 5 mm or less normally, Preferably it is 1 mm or less, More preferably, it is 1-500 micrometers, More preferably, it is 5-150 micrometers.

The second protective layer side opposite to the polarizer may be a hard coat treatment, an antireflection treatment, an anti-sticking treatment, an antiglare treatment, or the like, if necessary.

It is preferable that the thickness direction retardation Rth of the first protective layer provided between the polarizer and the optical compensation layer is smaller than the above preferable value. As described above, in the case of a cellulose-based 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. In order to reduce thickness direction retardation Rth, the cellulose-type film with a large thickness direction retardation Rth can be processed suitably, and a 1st protective layer can be obtained by a preferable method by this.

As a treatment for reducing the thickness direction retardation Rth, any suitable treatment method can be adopted. Examples include attaching a base made of polyethylene terephthalate, polypropylene, or stainless steel coated with a solvent such as cyclopentanone or methyl ethyl ketone to a general purpose cellulosic film, and heating the laminate (eg, After about 3 to 10 minutes) at about 80 to 150 ° C., and then peeling off the base; Then, a solution in which norbornene-based resins, acrylic resins, and the like are dissolved in a solvent such as cyclopentanone or methyl ethyl ketone is applied to a general-purpose cellulose-based film, and the laminate is heated and dried (for example, at about 80 to 150 ° C). About 3 to 10 minutes), and then a method of peeling the applied film.

Examples of the material for forming the cellulose-based film preferably include aliphatic acid-substituted cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose. Although the degree of acetic acid substitution in the commonly used triacetyl cellulose is about 2.8, by adjusting the degree of acetic acid substitution to 1.8 to 2.7, more preferably by adjusting the propionic acid substitution degree to 0.1 to 1, the thickness direction phase difference (Rth) can be controlled to be small. have.

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

The processing methods for reducing the thickness direction phase difference Rth may be appropriately mixed. The thickness direction retardation Rth (550) of the first protective layer obtained by this treatment is preferably -20 nm to +20 nm, more preferably -10 nm to +10 nm, even more preferably -6 nm to +6 nm, particularly preferably -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, even more preferably 0 nm or more and 3 nm or less.

As the thickness of the first protective layer, any suitable thickness can be adopted as long as the above preferred thickness direction retardation Rth can be obtained. Preferably the thickness of a 1st protective layer is 20-200 micrometers, More preferably, it is 30-100 micrometers, More preferably, it is 35-95 micrometers.

A-8. Lamination method

Arbitrary suitable methods can be employ | adopted as a method of laminating | stacking each layer (film). Specifically, each layer is laminated through any suitable pressure sensitive adhesive layer or adhesive layer. Representative examples of the pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive layer. The thickness of the acrylic pressure-sensitive adhesive layer is preferably 1 to 30 µm, more preferably 3 to 25 µm.

As described above, when the first optical compensation layer 12 functions as a protective layer of the polarizer 11, the polarizer and the first optical compensation layer are laminated through any suitable adhesive layer. As described above, when the first optical compensation layer having the refractive index ellipsoid of nx> ny> nz is produced by the fixed end biaxial stretching, the slow axis may be generated in one direction. On the other hand, the absorption axis direction of the polarizer can be generated in the stretching direction (longitudinal direction). That is, when the first optical compensation layer and the polarizer are arranged such that the slow axis of the first optical compensation layer is perpendicular to the absorption axis of the polarizer as in the present invention, the first optical compensation layer and the polarizer are formed by roll-to-roll. It can be stacked continuously. Examples of the adhesive used in the lamination of the polarizer and the first optical compensation layer include an adhesive containing a polyvinyl alcohol-based resin, a crosslinking agent and a colloidal metal compound.

Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol resins and polyvinyl alcohol resins containing acetoacetyl groups. Polyvinyl alcohol resins containing acetoacetyl groups are preferred because their durability can be improved.

Examples of the polyvinyl alcohol-based resins described above include saponified polyvinyl acetate and derivatives of saponified products thereof; Saponified copolymers obtained by copolymerizing vinyl acetate with monomers having copolymerizability; And modified polyvinyl alcohol obtained by modifying polyvinyl alcohol with acetal, urethane, ether, graft, or phosphate. Examples of monomers include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid and (meth) acrylic acid and esters thereof; α-olefins such as ethylene and propylene; (Sodium) (meth) allylsulfonate; Sodium sulfonate (monoalkylmaleate); Sodium disulfonate alkylmaleate; N-methylol acrylamide; Alkali salts of acrylamide alkylsulfonate; N-vinylpyrrolidone; And derivatives of N-vinylpyrrolidone. These resins can be used alone or in combination.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably about 100 to 5,000, more preferably 1,000 to 4,000 from the viewpoint of adhesiveness. The average saponification degree of the polyvinyl alcohol-based resin is preferably about 85 to 100 mol%, more preferably 90 to 100 mol% from the viewpoint of adhesiveness.

The polyvinyl alcohol resin containing an acetoacetyl group is obtained by, for example, reacting the polyvinyl alcohol resin with diketene by any method. Specific examples thereof include a method of adding diketene to a dispersion in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid, and a diketene in a solution in which the polyvinyl alcohol resin is dissolved in a solvent such as dimethylformamide or dioxane. And a method of bringing diketene gas or diketene liquid into direct contact with the polyvinyl alcohol-based resin.

Acetoacetyl group modification degree of the polyvinyl alcohol-based resin containing acetoacetyl group is usually 0.1 mol% or more, preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%, particularly preferably 2 to 7 mol % to be. If the degree of denaturation is less than 0.1 mol%, the water resistance may be insufficient. When the degree of modification exceeds 40 mol%, the effect of improving water resistance is small. Acetoacetyl group denaturation is a value measured by NMR.

As the crosslinking agent, any suitable crosslinking agent may be employed. Preferably, compounds each having at least two functional groups reactive with the polyvinyl alcohol resin may be used as the crosslinking agent. Examples of the compound include alkylene diamines having an alkylene group and two amino groups such as ethylene diamine, triethylene diamine and hexamethylene diamine; Isocyanates such as tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylol propane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane) triisocyanate, isophorone diisocyanate and its compounds Toxime block compounds or phenol block compounds thereof; Epoxides such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or triglycidyl ether, 1,6-hexane diol diglycidyl ether, trimethylol propane triglycidyl ether, Diglycidyl aniline and diglycidyl amine; Monoaldehydes such as formaldehyde, acetaldehyde, propion aldehyde and butyl aldehyde; Dialdehydes such as glyoxal, malondialdehyde, succinic aldehyde, glutaraldehyde, maleic dialdehyde and phthaldialdehyde; Amino-formaldehyde resins such as methylolurea, methylolmelamine, alkylated methylolurea, alkylated methylol melamine, acetoguanamine, or condensates of benzoguanamine with formaldehyde; And salts of sodium, potassium, divalent or trivalent metals such as magnesium, calcium, aluminum, iron and nickel and their oxides. Among them, amino-formaldehyde resins and dialdehydes are preferable. As an amino-formaldehyde resin, the compound which has a methylol group is preferable, and glyoxal is preferable as dialdehyde. Especially, the compound which has a methylol group is preferable, and methylol melamine is especially preferable.

The blending amount of the crosslinking agent may be appropriately set according to the kind of the polyvinyl alcohol resin or the like. Typically, the blending amount of the crosslinking agent is about 10 to 60 parts by weight, preferably 20 to 50 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol resin. This is because such blending amount of crosslinking agent is excellent in adhesiveness. When the blending amount of the crosslinking agent is large, the reaction of the crosslinking agent proceeds for a short time and the adhesive tends to gel. As a result, the use time (pot life) of the adhesive is very short, which can make it difficult to industrially use the adhesive. Since the adhesive agent of embodiment of this invention contains the metal compound colloid mentioned later, even if the blending quantity of a crosslinking agent is large, it can use an adhesive agent with outstanding stability.

The metal compound colloid may have a structure in which the metal compound fine particles are dispersed in the dispersion medium, and may be electrostatically stabilized by interaction between homogeneous charges of the fine particles and thus may have permanent stability. The average particle diameter of the fine particles forming the metal compound colloid may be any suitable value as long as it does not adversely affect optical properties such as polarization properties. The average particle diameter is preferably 1 to 100 nm, more preferably 1 to 50 nm. This is because the fine particles can be uniformly dispersed in the adhesive layer to maintain the adhesiveness and to suppress the occurrence of knick. The term “cnic” refers to local uneven defects formed at the interface between the polarizer and the protective layer (first optical compensation layer).

As the metal compound, any suitable compound can be adopted. Examples of metal compounds include metal oxides such as alumina, silica, zirconia, or titania; Metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, or calcium phosphate; And minerals such as celite, talc, clay or kaolin. Among them, alumina is preferable.

Metal compound colloids are typically in the form of colloidal solutions in which metal compound colloids are dispersed in a dispersion medium. Examples of dispersion media include water and alcohols. Solids concentration in the colloidal solution is usually about 1 to 50% by weight. The colloidal solution may contain acids such as nitric acid, hydrochloric acid and acetic acid as stabilizers.

The blending amount of the metal compound colloid (solid content) is preferably 200 parts by weight or less, more preferably 10 to 200 parts by weight, even more preferably 20 to 175 parts by weight, most preferably 30 to 100 parts by weight of the polyvinyl alcohol resin. It is-150 parts by weight. This is because the amount of blending can suppress the occurrence of crank while maintaining the adhesiveness.

The adhesive agent by embodiment of this invention is coupling agent, such as a silane coupling agent and a titanium coupling agent; Various tackifiers; UV absorbers; Antioxidants; And stabilizers such as heat stabilizers and water resistant stabilizers.

The adhesive form of the embodiment of the present invention is preferably an aqueous solution (resin solution). The resin concentration is preferably 0.1 to 15% by weight, more preferably 0.5 to 10% by weight in view of coatability, storage stability and the like. The viscosity of the resin solution is preferably 1 to 50 mPa · s. The pH of the resin solution is preferably 2 to 6, more preferably 2.5 to 5, still more preferably 3 to 5, and most preferably 3.5 to 4.5. In general, the surface charge of the metal compound colloid can be controlled by adjusting the pH. Surface charge is preferably a positive charge. Due to the presence of positive charges, the occurrence of nicks can be suppressed.

Arbitrary suitable methods can be employ | adopted as a method of preparing the said resin solution. For example, there is a method of first mixing a polyvinyl alcohol-based resin with a crosslinking agent, adjusting the mixture to an appropriate concentration, and blending the formed mixture with the metal compound colloid. Alternatively, after mixing the polyvinyl alcohol-based resin with the metal compound colloid, the crosslinking agent may be mixed with the mixture in consideration of the timing of use. The concentration of the resin solution can be adjusted after preparation of the resin solution.

B. liquid crystal panel

B-1. Overall composition of liquid crystal panel

2A is a schematic cross-sectional view of a liquid crystal panel according to an 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 (the backlight side in the illustrated example) of the liquid crystal cell 20, and the other side of the liquid crystal cell 20 ( Lamination film 30 disposed on the viewer side in the illustrated example. The laminated film 30 includes a polarizer 11 and a fifth optical compensation layer 16. In the laminated film 30, if necessary, a first protective layer is provided between the polarizer 11 and the fifth optical compensation layer 16, and the second protective layer is opposite to the fifth optical compensation layer 16. It is provided on the polarizer 11 side. Although not shown, the laminated film 30 may further include any other suitable optical compensation layer. As shown, the laminated optical film 10 'and the laminated | multilayer film 30 are arrange | positioned so that the side by which an optical compensation layer is provided may be located in the liquid crystal cell 20 side.

2B is a schematic cross-sectional view of a liquid crystal panel according to still another embodiment of the present invention. The liquid crystal panel 100 ′ is a liquid crystal cell 20, the laminated optical film 10 ′ of the present invention disposed on one side (the backlight side in the illustrated example) of the liquid crystal cell 20, and the other side of the liquid crystal cell 20 ( Lamination film 30 'disposed on the viewer side in the illustrated example. The laminated film 30 'includes a polarizer 11, a fifth optical compensation layer 16 and a sixth optical compensation layer 17. In the laminated film 30 ', if necessary, a first protective layer is provided between the polarizer 11 and the fifth optical compensation layer 16, and the second protective layer is opposite to the fifth optical compensation layer 16. On the polarizer 11 side. In addition, although not shown, the laminated film 30 'may further include any other suitable optical compensation layer. As shown, the laminated optical film 10 'and the laminated film 30' are arrange | positioned so that the side surface in which the optical compensation layer is provided may be located in the liquid crystal cell 20 side.

Unlike the example shown, the laminated optical film 10 may be disposed instead of the laminated optical film 10 '. In addition, unlike the illustrated example, the laminated optical film 10 '10 may be disposed on the viewing side, and the laminated films 30 and 30' may be disposed on the backlight side.

The fifth optical compensation layer 16 constituting the laminated films 30, 30 'is laminated so that the slow axis of the fifth optical compensation layer 16 defines any suitable angle with respect to the absorption axis of the polarizer 11. It is laminated | stacked on the polarizer 11 which comprises the films 30 and 30 '. The defined angle is preferably 30 to 60 °, more preferably 35 to 55 °, particularly preferably 40 to 50 °, most preferably 43 to 47 °.

It is preferable that the polarizers 11 and 11 arrange | positioned at the both sides of the liquid crystal cell 20 of liquid crystal panel 100, 100 'are arrange | positioned so that the absorption axis of the polarizers 11 and 11 may be substantially perpendicular to each other.

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 disposed between the substrates 21 and 21'. One substrate (color filter substrate) 21 is provided with a color filter (not shown) and a black matrix (not shown). The other substrate (active matrix substrate) 21 'is provided with a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, and a source signal for the scan line and the switching element for providing a gate signal to the switching element. Signal lines and pixel electrodes are provided (both not shown). Color filters may be provided on the active matrix substrate 21 '. The space (cell gap) between the substrates 21 and 21 'is controlled by a spacer (not shown). For example, an orientation film (not shown) formed of polyimide is provided on each side of each of the substrates 21, 21 ′ in contact with the liquid crystal layer 22.

As a driving mode of the liquid crystal cell 20, any suitable driving mode can be adopted. It is preferable that the drive mode is VA mode. 3A and 3B are schematic cross-sectional views showing alignment states of liquid crystal molecules in VA mode. As shown in Fig. 3A, when no voltage is applied, the liquid crystal molecules are vertically aligned with respect to the substrates 21 and 21 '. This vertical alignment is realized by disposing a nematic liquid crystal having negative dielectric anisotropy between the substrates on which the vertical alignment film (not shown) is formed, respectively. When light is incident from the surface of one substrate 21 in this state, linearly polarized light incident on the liquid crystal layer 22 through one polarizer 11 goes along the longitudinal direction of the vertically oriented liquid crystal molecules. Since birefringence does not occur in the longitudinal direction of the liquid crystal molecules, the incident light is absorbed by the other polarizer 11 having an absorption axis perpendicular to the one polarizer 11 without changing the polarization direction. In this way, a dark state is indicated when no voltage is applied (normally black mode). As shown in FIG. 3B, when a voltage is applied between the electrodes, the longitudinal axis of the liquid crystal molecules is oriented so as to be parallel to the substrate surface. The liquid crystal molecules in this state exhibit birefringence with respect to linearly polarized light incident on the liquid crystal layer 22 through the one polarizer 11, and the polarization state of the incident light changes according to the inclination of the liquid crystal molecules. Upon application of a predetermined maximum voltage, light passing through the liquid crystal layer is converted into linearly polarized light having a polarization direction rotated, for example, by 90 °. Thereby, light passes through the other polarizer 11, and the bright state is displayed. At the end of voltage application, the display returns to the dark state by the orientation holding force. The inclination of the liquid crystal molecules is controlled by changing the applied voltage so as to change the intensity of the light transmittance from the other polarizer 11. As a result, gray scale display can be implemented.

B-3. Fifth optical compensation layer

The fifth optical compensation layer 16 can function as a so-called λ / 4 plate. The fifth optical compensation layer can convert linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light), for example, as a λ / 4 plate. The fifth optical compensation layer can mainly compensate for the liquid crystal cell. The fifth optical compensation layer may have the same optical properties (refractive index ellipsoid, in-plane retardation, Nz coefficient, etc.) as the third optical compensation layer. In addition, the fifth optical compensation layer may 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 an index ellipsoid of nx = ny> nz. The sixth optical compensation layer can mainly compensate for the liquid crystal cell. The thickness direction retardation Rth ₆ of the sixth optical compensation layer may be set to any suitable value depending on the configuration of the liquid crystal panel or the like. The details are described in section B-5. The sixth optical compensation layer may be formed of the same material as the fourth optical compensation layer.

B-5. About the thickness direction phase difference of a 4th optical compensation layer and a 6th optical compensation layer

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

B-6. Lamination method

Arbitrary suitable methods can be employ | adopted as a lamination method of each layer (film). In particular, each layer is laminated through any suitable pressure sensitive adhesive layer or adhesive layer. Representative examples of the pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive layer. The thickness of the acrylic 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, even more preferably 3 µm to 30 µm. The thickness of another acrylic adhesive layer becomes like this. Preferably it is 1-30 micrometers, More preferably, it is 3-25 micrometers.

Hereinafter, the present invention will be described in detail through examples. However, the present invention is not limited to these examples. The measuring method of each characteristic is as follows.

(1) Measurement of phase difference value

Phase difference values were automatically measured using KOBRA-WPR manufactured by Oji Scientific Instruments. The measurement wavelength was 590 nm or 550 nm and the measurement temperature was 23 ° C.

(2) measurement of contrast 1

Using the optical property parameter of each optical compensation layer actually manufactured and measured, the computer simulation was performed about the liquid crystal panel of each Example and a comparative example. In the simulation, Shintech Inc., a simulator for liquid crystal display units. Preparative "LCD MASTER" was used.

(3) Contrast Measurement 2

White image and black image were displayed on the liquid crystal display device, and it measured by "Conoscope" (brand name) by AUTRONIC MELCHERS.

(Example 1)

(Polarizing plate)

After dyeing a polyvinyl alcohol film in an aqueous solution containing iodine, the film was 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 mu m, KC4UYW (trade name), manufactured by Konica Minola Holdings Inc.) as a protective layer was attached to both sides of the polarizer through a polyvinyl alcohol adhesive (thickness: 0.1 mu m). In-plane phase difference Re (550) of the protective layer was 0.9 nm, and thickness direction phase difference Rth (550) was 1.2 nm. This manufactured the polarizing plate. Re (550) shows the value measured with the light of wavelength 550nm at 23 degreeC.

(First optical compensation layer)

A long film of norbornene-based resin film (Zeonor (trade name), manufactured by Zeon, thickness: 60 μm, photoelastic coefficient: 3.1 × 10 ^-12 m 2 / N) was fixed at 158 ° C. at a factor of 3.0 for a fixed end transverse uniaxial stretching. Was prepared. The in-plane phase difference Re ₁ of the obtained film was 110 nm, the thickness direction phase difference Rth ₁ was 143 nm, and the Nz coefficient (Rth ₁ / Re ₁ ) was 1.3. The obtained film was punched into a size corresponding to the liquid crystal cell described later to obtain a first optical compensation layer.

(Second optical compensation layer)

Pellet resin of styrene-maleic anhydride copolymer ("Dylark D232" (trade name), manufactured by Nova Chemicals Japan Ltd.) is extruded at 270 ° C. using a single screw extruder and a T-die and melted in sheet form using a cooling drum. Resin was cooled and the film of thickness 100micrometer was obtained. Using a roll stretching machine, the film was free end uniaxially stretched in the transport direction at a temperature of 130 ° C. and a draw ratio of 1.6 times to obtain a film having a fast axis in the transport direction (longitudinal stretching step).

The film obtained at a temperature of 135 ° C. was fixed-uniaxially stretched in the width direction using a tenter stretching machine so that the film width was 1.6 times the film width after longitudinal stretching, thereby obtaining a biaxially stretched film having a thickness of 50 μm (laterally). Drawing step).

The retardation film thus obtained had a fast axis in the transport direction, and the refractive index ellipsoid had a relationship of nz>nx> ny, in-plane retardation Re ₂ was 19 nm, thickness retardation Rth ₂ was -80 nm, and Nz coefficient (Rth ₂ / Re ₂ ) was -4.2. The obtained retardation film was punched to a size corresponding to that of the liquid crystal cell described later to obtain a second optical compensation layer.

(Third optical compensation layer)

A long norbornene-based resin film (Zeonor (trade name), manufactured by Zeon, thickness: 40 μm, photoelastic coefficient: 3.10 × 10 ⁻¹² m 2 / N) was uniaxially stretched 1.52 times at 140 ° C., thereby preparing a long film. . The thickness of the obtained film was 35 ㎛, the in-plane retardation Re ₃ is 140 nm, the thickness direction retardation Rth is 140 nm _3. The obtained film was punched into a size corresponding to a liquid crystal cell described later to obtain a third optical compensation layer.

(4th optical compensation layer)

90 parts by weight of the nematic liquid crystalline compound represented by the following formula (1), 10 parts by weight of a chiral agent represented by the following formula (2), 5 parts by weight of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals Inc.) and methyl ethyl ketone 300 The weight parts were mixed so as to be uniform, to prepare a liquid crystal-coating liquid. Next, the liquid crystal-coating solution was applied onto a substrate (biaxially stretched PET film), heated at 80 ° C. for 3 minutes, polymerized by UV-light irradiation, and the cholesteric alignment fixing layer serving as the fourth optical compensation layer was obtained. It was formed on a substrate. The thickness of the cholesteric alignment fixed layer was 2.2 µm, the thickness direction phase difference Rth ₄ was 120 nm, and the in-plane phase difference Re ₄ was substantially zero.

(Formula 2)

(Fifth optical compensation layer)

The film obtained by the same method as the third optical compensation layer was used as the fifth optical compensation layer (Re ₅ : 140 nm, Rth ₅ : 140 nm).

(Sixth optical compensation layer)

The cholesteric alignment pinned layer obtained in the same manner as the fourth optical compensation layer was used as the sixth optical compensation layer (Re ₆ : substantially zero, Rth ₆ : 120 nm).

(Laminated Optical Film A)

The cholesteric alignment fixing layer as the fourth optical compensation layer was attached to the third optical compensation layer obtained above using an isocyanate-based adhesive (thickness: 5 µm), and the substrate (biaxially stretched PET film) was removed thereby. Laminate 1 was obtained in which the cholesteric alignment pinned layer was transferred to the third optical compensation layer.

The acrylic optical adhesive (thickness: 12 micrometers) was used for the 3rd optical compensation layer side surface of the laminated body 1, and the 2nd optical compensation layer, the 1st optical compensation layer, and the polarizing plate were laminated | stacked in the order mentioned. These layers are then used so that the slow axis of the first optical compensation layer is perpendicular to the polarizer absorption axis of the polarizer, the slow axis of the second optical compensation layer is perpendicular to the polarizer absorption axis of the polarizer, and the slow axis of the third optical compensation layer. It laminated | stacked so that it might become 45 degrees clockwise with respect to the polarizer absorption axis of this polarizing plate, and thereby laminated optical film A was manufactured.

(Laminated film B)

The cholesteric alignment fixing layer as the sixth optical compensation layer was attached to the fifth optical compensation layer obtained above using an isocyanate-based adhesive (thickness: 5 µm), and the substrate (biaxially stretched PET film) was removed thereby. Laminate 2 was obtained in which the cholesteric alignment pinned layer was transferred to the fifth optical compensation layer.

The polarizing plate was laminated | stacked on the 5th optical compensation layer side surface of the laminated body 2 through the acrylic adhesive (thickness: 12 micrometers). At this time, these layers were laminated so that the slow axis of the 5th optical compensation layer might be 45 degrees clockwise with respect to the polarizer absorption axis of a polarizing plate, and thus laminated film B was produced.

(Liquid crystal panel)

The liquid crystal cell was removed from the PlayStation Portable (mounted with a liquid crystal cell in VA mode) manufactured by Sony Corporation, and the laminated optical film A was attached to the backlight side of the liquid crystal cell through an acrylic adhesive (thickness: 20 μm). At this time, the laminated optical film A was attached so that a 4th optical compensation layer may be arrange | positioned at the liquid crystal cell side. In addition, the laminated | multilayer film B was attached to the visual recognition side of a liquid crystal cell through an acrylic adhesive (thickness: 20 micrometers). At this time, the laminated | multilayer film B was attached so that a 6th optical compensation layer may be arrange | positioned at the liquid crystal cell side. Moreover, laminated | multilayer film B was laminated | stacked so that the absorption axis of the polarizer of laminated optical film A might be perpendicular to the absorption axis of the polarizer of laminated film B. Specifically, the slow axis of the fifth optical compensation layer is 45 °, the slow axis of the third optical compensation layer is 135 °, and the second optical compensation layer is clockwise, with the absorption axis of the viewer-side polarizer as a reference (0 °). The lamination was performed such that the slow axis of 0 was 0 °, the slow axis of the first optical compensation layer was 0 °, and the absorption axis of the polarizer on the backlight side was 90 °. Thus, a liquid crystal panel was produced.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 4 shows the result. In addition, the viewing angle dependence of the contrast of the liquid crystal display device manufactured using the liquid crystal panel thus obtained was actually measured. 5 shows the result.

(Example 2)

(Laminated Optical Film C)

A laminated optical film C was obtained in the same manner as the laminated optical film A, except that lamination was performed such that the slow axis of the second optical compensation layer was parallel to the polarizer absorption axis of the polarizing plate.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film C was used instead of the laminated optical film A. Specifically, the slow axis of the fifth optical compensation layer is 45 °, the slow axis of the third optical compensation layer is 135 °, and the second optical compensation layer is clockwise, with the absorption axis of the viewer-side polarizer as a reference (0 °). The lamination was carried out so that the slow axis of was 90 °, the slow axis of the first optical compensation layer was 0 °, and the absorption axis of the polarizer on the backlight side was 90 °, thereby obtaining a liquid crystal panel.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 6 shows the result. In addition, the viewing angle dependence of the contrast of the liquid crystal display device manufactured using the liquid crystal panel thus obtained was actually measured. 7 shows the result.

(Example 3)

(Laminated Optical Film D)

A laminated optical film D is obtained in the same manner as in the laminated optical film A, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.59 times and the film was stretched at a stretch rate of 1.59 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 10 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- 8.0.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film D was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 8 shows the result.

(Example 4)

(Laminated Optical Film E)

The laminated optical film E is obtained by the same method as the laminated optical film A, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.61 times and the film was laterally stretched at a draw ratio of 1.61 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 30 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- Was 2.7.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film E was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 9 shows the result.

(Example 5)

(Laminated Optical Film F)

A laminated optical film F is obtained in the same manner as the laminated optical film A, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.62 times and the film was laterally stretched at a draw ratio of 1.62 times. The index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 40 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- Was 2.0.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film F was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 10 shows the result.

(Example 6)

(Laminated Optical Film G)

The laminated optical film G is obtained by the same method as the laminated optical film A, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.63 times and the film was laterally stretched at a draw ratio of 1.63 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 50 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- It was 1.6.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film G was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 11 shows the result.

(Example 7)

(Laminated Optical Film H)

The laminated optical film H is obtained by the same method as the laminated optical film C, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.59 times and the film was laterally stretched at a draw ratio of 1.59 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 10 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- 8.0.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film H was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 12 shows the result.

(Example 8)

(Laminated Optical Film I)

The laminated optical film I is obtained by the same method as the laminated optical film C, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.61 times and the film was laterally stretched at a draw ratio of 1.61 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 30 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- Was 2.7.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film I was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 13 shows the result.

(Example 9)

(Laminated Optical Film J)

A laminated optical film J is obtained in the same manner as the laminated optical film C, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.62 times and the film was laterally stretched at a draw ratio of 1.62 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 40 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was -2.0 It was.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film J was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 14 shows the result.

(Example 10)

(Laminated Optical Film K)

The laminated optical film K is obtained by the same method as the laminated optical film C, except that the following film is used as the second optical compensation layer.

(Second optical compensation layer)

A second optical compensation layer was obtained in the same manner as in Example 1 except that the film was longitudinally stretched at a draw ratio of 1.63 times and the film was laterally stretched at a draw ratio of 1.63 times. The refractive index ellipsoid of the film had a relationship of nz>nx> ny, the in-plane retardation Re ₂ was 50 nm, the thickness retardation Rth ₂ was -80 nm, and the Nz coefficient (Rth ₂ / Re ₂ ) was- It was 1.6.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated optical film K was used instead of the laminated optical film A.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 15 shows the result.

(Comparative Example 1)

(Laminated film L)

A laminated film L 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.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated film L was used instead of the laminated optical film A. Specifically, in the clockwise direction with the absorption axis of the viewer-side polarizer as reference (0 °), the slow axis of the fifth optical compensation layer is 45 °, the slow axis of the third optical compensation layer is 135 °, and the absorption axis of the polarizer on the backlight side is Lamination was carried out at 90 °, whereby a liquid crystal panel was prepared.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 16 shows the result. In addition, the viewing angle dependence of the contrast of the liquid crystal display device manufactured using the liquid crystal panel thus obtained was actually measured. 17 shows the result.

(Comparative Example 2)

(Laminated film M)

A laminated film M was obtained in the same manner as the laminated optical film A, except that the first optical compensation layer was not laminated.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that the laminated film M was used instead of the laminated optical film A. Specifically, in the clockwise direction with the absorption axis of the viewer-side polarizer as a reference (0 °), the slow axis of the fifth optical compensation layer is 45 °, the slow axis of the third optical compensation layer is 135 °, and the ground of the second optical compensation layer is Lamination was performed such that the axis was 0 ° and the absorption axis of the polarizer on the backlight side was 90 °, thereby manufacturing a liquid crystal panel.

Regarding the viewing angle dependence of the contrast of the liquid crystal display device using the liquid crystal panel, computer simulation was performed. 18 shows the result. In addition, the viewing angle dependence of the contrast of the liquid crystal display device manufactured using the liquid crystal panel thus obtained was actually measured. 19 shows the result.

(Comparative Example 3)

(Laminated film N)

The laminated film N is obtained by the same method as the laminated optical film C, except that the first optical compensation layer is not laminated.

(Liquid crystal panel)

A liquid crystal panel was obtained in the same manner as in Example 1 except that laminated film N was used instead of laminated optical film A. Specifically, in the clockwise direction with the absorption axis of the viewer-side polarizer as a reference (0 °), the slow axis of the fifth optical compensation layer is 45 °, the slow axis of the third optical compensation layer is 135 °, and the ground of the second optical compensation layer is Lamination was performed such that the axis was 90 ° and the absorption axis of the polarizer on the backlight side was 90 °, thereby manufacturing a liquid crystal panel.

Regarding the viewing angle dependence of the contrast of the liquid crystal display using the liquid crystal panel, a computer simulation was performed. 20 shows the result.

The contour lines shown in the computer simulation results (Figs. 4, 6, 8-16, 18 and 20) represent 100, 50, 40, 30, 20 and 10 from the inside, respectively.

Table 1 summarizes the whole structure of the panels of Examples 1 and 2 and Comparative Examples 1-3. In addition, Table 1 shows the angle (clockwise direction) when the angle of the absorption axis of the polarizer of the visual recognition side becomes 0 degree.

As apparent from FIGS. 4-20, the liquid crystal panel by Examples 1-10 of this invention was excellent in contrast compared with Comparative Examples 1-3. Moreover, it was confirmed that the color shift of the liquid crystal panel by the Example of this invention is smaller than the liquid crystal panel by a comparative example.

The liquid crystal panel and liquid crystal display device of the present invention can be advantageously applied to cellular phones, personal digital assistants (PDAs), liquid crystal televisions, personal computers and the like.

Many other modifications are apparent to those skilled in the art and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, the scope of the appended claims should not be limited by the detailed description of the invention, but rather should be construed broadly.

1A is a schematic cross-sectional view of a laminated optical film according to a preferred embodiment of the present invention.

1B is a schematic cross-sectional view of a laminated optical film according to another preferred embodiment of the present invention.

2A is a schematic cross-sectional view of a liquid crystal panel according to one embodiment of the present invention.

2B is a schematic cross-sectional view of a liquid crystal panel according to still another preferred embodiment of the present invention.

3A and 3B are schematic cross-sectional views showing alignment states of liquid crystal molecules in a liquid crystal layer when a liquid crystal cell in VA mode is employed in the liquid crystal display device of the present invention.

Fig. 4 is a diagram showing the results of computer simulation regarding the viewing angle dependence of the contrast of the liquid crystal panel in Example 1 of the present invention.

Fig. 5 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel in Example 1 of the present invention.

Fig. 6 is a diagram showing the results of computer simulations regarding the viewing angle dependence of the contrast of the liquid crystal panel in Example 2 of the present invention.

Fig. 7 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel in Example 2 of the present invention.

Fig. 8 is a diagram showing the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 3 of the present invention.

Fig. 9 is a view showing the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 4 of the present invention.

Fig. 10 is a view showing the results of computer simulations regarding the viewing angle dependence of the contrast of the liquid crystal panel in Example 5 of the present invention.

Fig. 11 is a view showing the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 6 of the present invention.

Fig. 12 shows the results of computer simulation relating to the viewing angle dependence of the contrast of the liquid crystal panel in Example 7 of the present invention.

Fig. 13 is a view showing the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 8 of the present invention.

Fig. 14 shows the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 9 of the present invention.

Fig. 15 is a view showing the results of computer simulation relating to the viewing angle dependency of contrast of a liquid crystal panel in Example 10 of the present invention.

FIG. 16 is a diagram showing results of computer simulations relating to viewing angle dependence of contrast of a liquid crystal panel in Comparative Example 1. FIG.

FIG. 17 is a contrast contour map showing the viewing angle dependence of contrast of a liquid crystal panel in Comparative Example 1. FIG.

18 is a diagram showing results of computer simulations relating to viewing angle dependence of contrast of a liquid crystal panel in Comparative Example 2. FIG.

FIG. 19 is a contrast contour map showing the viewing angle dependence of contrast of a liquid crystal panel in Comparative Example 2. FIG.

20 is a diagram showing results of computer simulations relating to viewing angle dependence of contrast of a liquid crystal panel in Comparative Example 3. FIG.

Claims (9)

Polarizer; A first optical compensation layer in which the index ellipsoid has a relationship of nx> ny> nz; And The index ellipsoid comprises a second optical compensation layer exhibiting a relationship of nz> nx> ny, The polarizer and the first optical compensation layer are disposed such that an absorption axis of the polarizer is parallel or perpendicular to a slow axis of the first optical compensation layer, The polarizer and the second optical compensation layer are disposed such that the absorption axis of the polarizer is parallel or perpendicular to the slow axis of the second optical compensation layer. The method of claim 1, The laminated optical film whose Nz coefficient of a said 2nd optical compensation layer is -1.0 or less. The method of claim 1, The laminated optical film in which the in-plane retardation Re ₂ of the second optical compensation layer satisfies a relationship of 0 nm <Re ₂ ≤ 70 nm. The method of claim 1, A laminated optical film, wherein the refractive ellipsoid further comprises a third optical compensation layer exhibiting a relationship of one of nx> ny = nz and nx> ny> nz. The method of claim 4, wherein The laminated optical film whose in-plane phase difference Re ₃ of the said 3rd optical compensation layer is 80-200 nm. The method of claim 1, The laminated optical film in which a refractive index ellipsoid further contains the 4th optical compensation layer which shows the relationship of nx = ny> nz. The liquid crystal panel containing the liquid crystal cell and the laminated optical film of Claim 1. The method of claim 7, wherein Wherein said liquid crystal cell is in VA mode. The liquid crystal display device containing the liquid crystal panel of Claim 7.

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