JP2006002025A - Cellulose acylate preparation and cellulose acylate film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate preparation for melt casting use capable of forming by melt casting cellulose acylate film causing no color mismatching even if incorporated into a liquid crystal display device, and to provide such cellulose acylate film obtained by melt casting of such a cellulose acylate preparation. <P>SOLUTION: The cellulose acylate film formed by melt casting has a transmission-measured YI (Yellowness Index) determined by the following numerical formula (1) of 0-10. The numerical formula (1) is as follows: transmission-measured YI=[(1.28X-1.06Z)/Y]×100×(100/d) (wherein, X, Y and Z are three excitation values determined in accordance with JIS K-7105 6.3 using a color-difference meter; and d is the thickness (μm) of the cellulose acylate film). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cellulose acylate preparation for melt casting, and a cellulose acylate film formed from the cellulose acylate preparation by melt casting. The cellulose acylate film of the present invention is used as an optical film.

  Conventionally, when producing a cellulose acylate film used in a liquid crystal image display device, it is dissolved in a chlorinated organic solvent such as dichloromethane, and this is cast on a substrate and dried to form a film. The law is mainly implemented. Dichloromethane has been conventionally used as a good solvent for cellulose acylate as a chlorinated organic solvent, and is preferably used due to the advantage that it is easy to dry because of its low boiling point (boiling point of about 40 ° C.) in the film formation and drying steps of the production process. Yes. In recent years, from the viewpoint of environmental protection, leakage of chlorine-based organic solvents having a low boiling point into the atmosphere has been significantly reduced by being handled in a sealed facility. Furthermore, in the unlikely event of leakage, a gas absorption tower is installed before adsorbing to the outside air and the organic solvent is adsorbed for treatment, combustion before heating or decomposition of the chlorinated organic solvent by an electron beam, etc. Organic solvents are no longer emitted, but further research is needed before complete non-emission.

As such a countermeasure, Patent Document 1 proposes a method for melt-forming cellulose acylate as a film forming method that does not use an organic solvent. In this method, the cellulose acylate is heated and melted to a temperature at which fluidity is exhibited, and then the cellulose acylate in a fluid state is extruded onto an endless belt or drum to form a film. In this technique, a cellulose acylate having a long ester chain carbon chain to lower the melting point and facilitating melt film formation is preferably used. Specifically, cellulose acetate, cellulose propionate and cellulose are used. By changing to butyrate or the like, melt film formation is facilitated. However, when a polarizing plate was prepared by using a film formed by melting in accordance with the method described in Patent Document 1 and incorporated in a liquid crystal display device, an improvement in color shift was desired.
JP 2000-352620 A

  An object of the present invention is to provide an excellent cellulose acylate film that eliminates the color shift that occurs when a polarizing plate using a cellulose acylate film formed into a melt is incorporated into a liquid crystal display device.

  Another object of the present invention is to provide a cellulose acylate preparation for melt casting capable of melt-forming the above-described excellent cellulose acylate film.

  As a result of research, the present inventors have solved the color shift that occurs when incorporated in a liquid crystal display device by setting the YI (Yellowness Index) in the measurement range of the cellulose acylate film within a specific range. I found.

  As a result of advancing research, the present inventors have found that the cause of color misregistration is caused by subtle coloring (yellowing) that occurs during melt film formation of cellulose acylate. In order to melt the cellulose acylate, heat and shearing force (the force by which the screw of the kneading extruder strongly rubs and kneads the cellulose acylate) is applied, but at the same time, the cellulose acylate is decomposed and yellowed (yellowing) )cause. This is considered to cause color misregistration when the cellulose acylate film is incorporated into a liquid crystal display element.

  As a result of further research, in order to improve such yellowing, at least one rod-shaped compound having a specific structure is contained in the cellulose acylate, so that the cellulose acylate in the kneading extruder is preferably used. It was found that coloring due to decomposition can be specifically suppressed.

That is, the above object of the present invention is achieved by the following configuration.
(1) A cellulose acylate film formed by melt casting, wherein a YI (Yellowness Index) of permeation measurement obtained by the following formula (1) is 0 or more and 10 or less. .
Formula (1): YI of transmission measurement = {(1.28X−1.06Z) / Y} × 100 × (100 / d)
(Here, X, Y, Z are tristimulus values measured according to 6.3 of JIS K-7105 using a color difference meter, and d is the thickness (μm) of the cellulose acylate film.)

(2) A cellulose acylate preparation for melt casting comprising at least one rod-like compound represented by the following general formula (1).
Ar ¹ -L ¹ -Ar ² (1)
(In the formula, Ar ¹ and Ar ² are each independently an aromatic group, and L ¹ is selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and combinations thereof) Divalent linking group)

(3) The cellulose acylate preparation for melt casting according to (2), wherein the rod-like compound described in the general formula (1) is contained in an amount of 0.1% by mass to 40% by mass with respect to the cellulose acylate.

(4) The cellulose acylate preparation according to (2) or (3), wherein the substitution degree of the acyl group of cellulose acylate satisfies the following mathematical formulas (2) to (4).
Formula (2): 2.5 ≦ X + Y <3.0
Formula (3): 0 ≦ X ≦ 1.8
Formula (4): 1.0 ≦ Y <3
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the total degree of substitution of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.)

(5) The cellulose acylate preparation according to any one of (2) to (4), further comprising at least one of propanoic acid, butanoic acid, pentanoic acid, and hexanoic acid in an amount of 1 ppm to 1000 ppm.

(6) A method for producing a cellulose acylate film, comprising melting and casting the cellulose acylate preparation for melt casting according to any one of (2) to (5) above.
(7) Formed by casting the cellulose acylate preparation according to (3) above, containing the rod-shaped compound according to the general formula (1) in an amount of 0.1% by mass to 15% by mass with respect to the cellulose acylate. The cellulose acylate film as described in (1) above, wherein
(8) A cellulose acylate film produced by melting and casting the cellulose acylate preparation for melt casting according to any one of (2) to (5) above.
(9) A stretched cellulose acylate film obtained by stretching the cellulose acylate film according to any one of (1), (7), or (8) at least 10% to 300% in at least a uniaxial direction.

(10) The cellulose according to any one of (1), (7), (8) and (9), wherein the in-plane retardation (Re) and the thickness direction retardation (Rth) are 20 nm or more and 800 nm or less. Acylate film.
(11) The cellulose acylate according to any one of (1), (7), (8), (9) and (10), wherein at least one of Re and Rth humidity fluctuations is 0% or more and 15% or less. the film.

(12) A polarizing plate comprising at least one layer of the cellulose acylate film according to any one of (1), (7), (8), (9) or (10) laminated on a polarizing film.
(13) An optical compensation film for a liquid crystal display panel using the cellulose acylate film according to any one of (1), (7), (8), (9) or (10) as a substrate.
(14) An antireflection film using the cellulose acylate film according to any one of (1), (7), (8), (9) or (10) as a substrate.

  When the cellulose acylate preparation for melt casting according to the present invention is incorporated in a liquid crystal display device, an excellent cellulose acylate film that does not cause problems such as color shift can be obtained.

  Hereinafter, the present invention will be described in detail. In the present specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”. . The description “(meth) acryloyl” means “at least one of acryloyl and methacryloyl”. The same applies to “(meth) acrylate”, “(meth) acrylic acid” and the like.

As described above, the cellulose acylate film of the present invention is formed by solution casting, and has a YI (Yellowness Index) of permeation measurement obtained by the following formula (1) of 0 or more and 10 or less.
Formula (1): YI of transmission measurement = {(1.28X−1.06Z) / Y} × 100 × (100 / d)
(Here, X, Y, Z are tristimulus values measured according to 6.3 of JIS K-7105 using a color difference meter, and d is the thickness (μm) of the cellulose acylate film.)
The range of YI is 0 or more and 10 or less, more preferably 0 or more and 7 or less, and still more preferably 0 or more and 5 or less.

  The cellulose acylate preparation of the present invention preferably contains cellulose acylate and at least one rod-like compound.

  The rod-shaped compounds may be used alone or in combination. A preferable content is 0.1% by mass or more and 15% by mass or less, more preferably 0.3% by mass or more and 12% by mass or less, and more preferably 0% by mass with respect to the cellulose acylate in the formed cellulose acylate film. .8 mass% or more and 8 mass% or less. When two or more kinds of rod-shaped compounds are mixed and used, these contents indicate the total of the rod-shaped compounds to be added.

  By adding a rod-shaped ring compound, it is possible to impart the characteristics that the in-plane retardation (Re) and the thickness direction retardation (Rth) of the obtained cellulose acylate film can be easily obtained, which is preferable. In the present invention, Re and Rth are expressed by the following mathematical formulas (5) and (6), and Re is an index of the difference in refractive index between the longitudinal direction (MD) and the width direction (TD) in the plane, and Rth Is an indicator of the difference between the in-plane average refractive index and the refractive index in the thickness direction. A cellulose acylate film having such Re and Rth is more preferable because it can have a wide viewing angle when incorporated in a liquid crystal display panel. Preferable Re and Rth are 20 nm to 800 nm, more preferably 25 nm to 500 nm, and further preferably 30 nm to 300 nm. Further, Re ≦ Rth is preferable, Re × 1.5 ≦ Rth is more preferable, and Re × 2 ≦ Rth is more preferable. Such Re and Rth can be expressed more remarkably by stretching described later.

Formula (5): Re = (n _md −nt _d ) × d
Formula (6): Rth = | {(n _md + n _td ) / 2} −n _th | × d

Here, n _md , n _td , and n _th indicate the refractive index in the longitudinal direction (MD), the width direction (TD), and the thickness direction (Th), respectively, and d indicates the thickness (expressed in nm). .

  By adding a rod-shaped ring compound, it is possible to impart the characteristics that Re and Rth hardly change with humidity, which is preferable. At least one of Re and Rth humidity fluctuations is preferably 0% or more and 15% or less, more preferably 0% or more and 10% or less, and further preferably 0% or more and 7% or less. The humidity Re and Rth humidity fluctuations herein are the absolute values of the difference between the Re and Rth values measured at 25 ° C. and 80% RH, and the Re and Rth values measured at 25 ° C. and 10% RH, respectively. It is expressed as a percentage by the values of Re and Rth measured at 25 ° C. and 60% RH.

[Rod compound]
In the present invention, it is also preferable to use a rod-shaped compound having an absorption maximum on the shorter wavelength side than 250 nm. Such a rod-like compound preferably has at least one aromatic ring, and more preferably has at least two aromatic rings.

  The rod-shaped compound used in the present invention preferably has a linear molecular structure. Here, the linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation is performed using molecular orbital calculation software {for example, “WinMOPAC2000” manufactured by Fujitsu Limited}, and a molecular structure that minimizes the heat of formation of a compound can be obtained. The molecular structure being linear means that the angle of the molecular structure is 140 ° or more in the thermodynamically most stable structure obtained by calculation as described above.

As the rod-like compound, a compound represented by the following general formula (1) is preferable.
Ar ¹ -L ¹ -Ar ² (1)

In the general formula (1), Ar ¹ and Ar ² are each independently an aromatic group. In this specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group. Of these aromatic groups, aryl groups and substituted aryl groups are preferred.

The aromatic ring of the aryl group (aromatic hydrocarbon group) is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. These aromatic rings may be single or two or more may be linked. Examples include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, indene ring, biphenyl, terphenyl and the like. Of these, a benzene ring is particularly preferred.
The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine Rings, pyridazine rings, pyrimidine rings, pyrazine rings, and 1,3,5-triazine rings are included.

  As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino group (for example, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (for example, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (for example, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (for example, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg methyl, ethyl, propyl) Butyl, pentyl, heptyl, octyl, isopropyl, sec-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl groups (eg, vinyl, allyl, hexenyl), alkynyl groups (eg, ethynyl, butynyl), acyl groups (eg, Formyl, acetyl, butyryl, hexanoyl, lauryl), acyloxy groups (eg acetoxy, butyryloxy, hexanoyloxy, lauryloxy), alkoxy groups (eg methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy, octyloxy) An aryloxy group (eg, phenoxy), an alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, Butyloxycarbonyl), aryloxycarbonyl groups (eg phenoxycarbonyl), alkoxycarbonylamino groups (eg butoxycarbonylamino, hexyloxycarbonylamino), alkylthio groups (eg methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, Octylthio), arylthio groups (eg, phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamido, butyramide, hexyl) Amide, laurylamide) and non-aromatic heterocyclic groups (eg, morpholyl, pyrazinyl).

  Substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms, cyano, carboxyl, hydroxyl, amino, alkyl-substituted amino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthios. And groups and alkyl groups are preferred. The alkyl moiety of the alkylamino group, alkoxycarbonyl group, alkoxy group, and alkylthio group and the alkyl group may further have a substituent. Examples of alkyl moieties and substituents of alkyl groups include halogen atoms, hydroxyl, carboxyl, cyano, amino, alkylamino groups, nitro, sulfo, carbamoyl, alkylcarbamoyl groups, sulfamoyl, alkylsulfamoyl groups, ureido, alkylureido Group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, alkylsulfonyl group, amide group and non-aromatic An aromatic heterocyclic group is included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, hydroxyl, amino, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group and alkoxy group are preferable.

In the general formula (1), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and combinations thereof. The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group. The number of carbon atoms of the alkylene group is preferably 1 to 20, more preferably 1 to 15, further preferably 1 to 10, particularly preferably 1 to 8, and 1 to 6 Most preferably.

  The alkenylene group and the alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure. The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, particularly preferably 2 to 4, Most preferred is 2 (vinylene or ethynylene).

The example of the bivalent coupling group which consists of a combination is shown.
L-1: —O—CO-alkylene group —CO—O—
L-2: -CO-O-alkylene group -O-CO-
L-3: —O—CO—alkenylene group —CO—O—
L-4: -CO-O-alkenylene group -O-CO-
L-5: -O-CO-alkynylene group -CO-O-
L-6: -CO-O-alkynylene group -O-CO-

In the molecular structure of the general formula (1), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 ° or more. As the rod-like compound, a compound represented by the following general formula (2) is more preferable.
Ar ¹ -L ² -XL ³ -Ar ² (2)

In the general formula (2), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (1).

In the general formula (2), L ² and L ³ are each independently a divalent linking group selected from the group consisting of an alkylene group, —O—, —CO—, and combinations thereof. The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure. The number of carbon atoms of the alkylene group is preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, particularly preferably 1 to 4, 1 or 2 Most preferred is (methylene or ethylene). L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene. Specific examples of the compound represented by the general formula (1) are shown below.

  Specific examples (1) to (34), (41) and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41) and (42) have a symmetric meso type molecular structure, there are no optical isomers (optical activity) and geometric isomers ( There are only trans and cis). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

  As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type. Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate. In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as above, the trans type is preferable to the cis type.

In the ultraviolet absorption spectrum of the rod-shaped compound solution, two or more rod-shaped compounds whose maximum absorption wavelength (λ _max ) is shorter than 250 nm may be used in combination. The rod-like compound can be synthesized with reference to methods described in literature. References include “Mol. Cryst. Liq. Cryst.”, 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170. 43 (1989), “J. Am. Chem. Soc.”, 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970). "J. Org. Chem.", 40, 420 (1975), "Tetrahedron", 48, 16, 3437 (1992).
The rod-shaped compound of the present invention may be used alone or in combination of two or more types of compounds.

  Moreover, you may use a benzoic acid phenylester compound or a triazine ring compound instead of a rod-shaped compound for the improvement of yellowing of a cellulose acylate film. Of these, rod-like compounds are preferred.

[Cellulose acylate resin]
The cellulose acylate used in the present invention preferably has the following characteristics. That is, cellulose acylate in which the acyl group substitution degree of cellulose acylate satisfies the following mathematical formulas (2) to (4) is preferable.

Formula (2): 2.5 ≦ X + Y <3.0
Formula (3): 0 ≦ X ≦ 1.8
Formula (4): 1.0 ≦ Y <3
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the total degree of substitution of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.)

More preferred cellulose acylates are:
Formula (4-1): 1.25 ≦ Y <3

Further preferred cellulose acylates are:
When 1/2 or more of Y is a propionyl group, the following mathematical formulas (2-2) and (4-2) are satisfied,
Formula (2-2): 2.6 ≦ X + Y ≦ 2.95
Formula (4-2): 2.0 ≦ Y ≦ 2.95
When less than 1/2 of Y is a propionyl group, the following mathematical formulas (2-3) and (4-3) are satisfied.
Formula (2-3): 2.6 ≦ X + Y ≦ 2.95
Formula (4-3): 1.3 ≦ Y ≦ 2.5

Particularly preferred cellulose acylates are:
When 1/2 or more of Y is a propionyl group, the following mathematical formulas (2-4) and (4-4) are satisfied,
Formula (2-4): 2.7 ≦ X + Y ≦ 2.95
Formula (4-4): 2.4 ≦ Y ≦ 2.9
When less than 1/2 of Y is a propionyl group, the following mathematical formulas (2-5) and (4-5) are satisfied.
Formula (2-5): 2.7 ≦ X + Y ≦ 2.95
Formula (4-5): 1.3 ≦ Y ≦ 2.0

  In the present invention, it is preferable to use a cellulose acylate with a reduced degree of acetyl group substitution and an increased sum of the degree of substitution of propionyl group, butyryl group, pentanoyl group and hexanoyl group. As a result, unevenness in stretching is less likely to occur during stretching, Re, Rth unevenness is unlikely to occur, crystal melting temperature (Tm) can be lowered, and yellowing that occurs due to thermal decomposition of melt film formation is suppressed. Can also be preferred. These effects can be achieved by using as large a substituent as possible, but if it is too large, the glass transition temperature (Tg) and the elastic modulus may be lowered too much. Therefore, a propionyl group, butyryl group, pentanoyl group larger than the acetyl group may be obtained. It is preferable to use a large number of hexanoyl groups, more preferably a propionyl group, a butyryl group, and even more preferably a butyryl group.

  The basic principle of these cellulose acylate synthesis methods is described in Mita et al., Wood Chemistry, pages 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst.

  Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylic acid mixture to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After the acylation reaction is completed, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide).

  Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added into the cellulose acylate solution) to separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.

  The degree of polymerization of the cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization of 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably a viscosity average degree of polymerization of 250 to 350. . The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.

  Such adjustment of the degree of polymerization can also be achieved by removing low molecular weight components. When the low molecular component is removed, the average molecular weight (degree of polymerization) increases, but the viscosity becomes lower than that of normal cellulose acylate, which is useful. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. Further, the molecular weight can be adjusted by a polymerization method. For example, when producing a cellulose citrate with a small amount of low molecular components, the amount of sulfuric acid catalyst in the acetylation reaction is preferably adjusted to 0.5 to 25 parts by mass with respect to 100 parts by mass of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized.

  The cellulose acylate used in the present invention preferably has a mass average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, more preferably 2.0 to 5.0, and still more preferably. Is 2.5 to 5.0, and a cellulose acylate of 3.0 to 5.0 is particularly preferably used.

  These cellulose acylates may be used alone or in combination of two or more. Further, a polymer component other than cellulose acylate may be appropriately mixed. The polymer component to be mixed is preferably one having excellent compatibility with cellulose acylate, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, more preferably 92% or more. preferable.

[Propanoic acid, butanoic acid, pentanoic acid, hexanoic acid]
In the present invention, in the cellulose acylate preparation (and the cellulose acylate film formed from the preparation), at least one of propanoic acid, butanoic acid, pentanoic acid, and hexanoic acid is 1 ppm to 1000 ppm, more preferably 10 ppm. It is preferably contained in an amount of 800 ppm or less, more preferably 20 ppm or more and 600 ppm or less. By containing such an acid, although the mechanism is not clear, it has the effect of suppressing YI of the cellulose acylate film by a synergistic effect with the rod-shaped compound.

[Plasticizer]
Furthermore, in this invention, you may add a plasticizer in a cellulose acylate formulation (and a cellulose acylate film formed from this formulation). Examples of the plasticizer include alkyl phthalyl alkyl glycolates, phosphoric acid esters and carboxylic acid esters.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Furthermore, it is preferable to use the phosphate ester plasticizer according to claims 3 to 7 of JP-T-6-501040.

  Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diethylhexyl phthalate; for example, citrates such as acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate. Adipic acid esters such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, bis (butyl diglycol adipate) and the like can be mentioned. In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.

  These plasticizers are preferably 0% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and further preferably 2% by mass or more and 15% by mass or less with respect to the cellulose acylate film. These plasticizers may be used in combination of two or more if necessary.

[Other additives]
In addition to the plasticizer, the cellulose acylate preparation of the present invention (and the cellulose acylate film formed from the preparation) include various additives {for example, an ultraviolet ray inhibitor, a deterioration inhibitor, and an optical anisotropy control. Agents, fine particles, infrared absorbers, surfactants, odor trapping agents (such as amines), etc.} can be added.

  As the infrared absorbing dye, for example, those disclosed in JP-A No. 2001-194522 can be used, and as the ultraviolet absorber, for example, those described in JP-A No. 2001-151901 can be used. It is preferable to contain -5 mass%.

  As the fine particles, those having an average particle diameter of 5 to 3000 nm are preferably used, and those composed of a metal oxide or a crosslinked polymer can be used, and 0.001 to 5% by mass with respect to cellulose acylate. It is preferable to contain.

  The deterioration inhibitor is preferably contained in an amount of 0.0001 to 2% by mass with respect to the cellulose acylate.

  As the optical anisotropy control agent, for example, those described in JP-A-2003-66230 and JP-A-2002-49128 can be used, and it is preferable to contain 0.1 to 15% by mass with respect to cellulose acylate.

[Cellulose acylate film]
The cellulose acylate film of the present invention is preferably produced by melting and casting a cellulose acylate preparation for melt casting containing cellulose acylate and at least one rod-like compound. Although the shape as a formulation is not specifically limited, A powder form or a pellet form is preferable.

[Formulation]
In the present invention, when producing a cellulose acylate film by melt casting, the cellulose acylate is formulated prior to film formation. As a formulation, it is preferable to form a powder or pellet. Under the present circumstances, it is preferable to formulate together with the said rod-shaped compound, a plasticizer, and another additive. The amount of these additives may be mixed so that the final amount required for the film may be added, or a formulation with a larger amount added (hereinafter referred to as “master” Also referred to as “pellet”). When creating a master pellet, use a preparation (powder or pellet) that is not added with additives or less than the amount required for the film, and dilute to form the required amount. . A preferable addition amount of these additives into the master pellet is 0.1% by mass or more and 40% by mass or less, more preferably 0.3% by mass or more and 30% by mass or less, more preferably 0.8% by mass or more. It is 20 mass% or less. Thereby, yellowing during pellet preparation can be suppressed and YI can be reduced.

  The YI of the pellet is measured by the reflection method. The preferred reflection measurement YI of the cellulose acylate pellets of the present invention is preferably 40 or less, more preferably 30 or less, and even more preferably 20 or less. By making YI of a pellet into such a range, it has the effect of reducing YI of the film melt-cast using this pellet, and is preferable.

In addition, YI by the reflection measurement of a pellet measures tristimulus values X, Y, and Z by reflection measurement according to JIS K-7105 6.3 using a color difference meter, and YI of reflection measurement is obtained from the following formula (7). It is what I have sought.
Formula (7): YI of reflection measurement = {(1.28X−1.06Z) / Y} × 100

  Before pelletization, the cellulose acylate, rod-shaped compound, plasticizer, and other additives may be dried until the moisture content is 1% by mass or less, more preferably 0.1% by mass or less. preferable.

Pelletization is carried out using a twin-screw kneading extruder and is 150 ° C. or higher and 220 ° C. or lower, more preferably 160 ° C. or higher and 210 ° C. or lower, more preferably 170 ° C. or higher and 200 ° C. or lower, and screw rotation speed 30 rpm or higher and 800 rpm or lower, more preferably The kneading is performed at 80 rpm to 600 rpm, more preferably 120 rpm to 400 rpm, and a residence time of 15 seconds to 5 minutes, more preferably 20 seconds to 4 minutes, and further preferably 20 seconds to 2 minutes. At this time, the rod-like compound, the plasticizer, and other additives may be mixed with cellulose acylate from the beginning and supplied to the kneading extruder, or may be added from a port provided in the middle of the kneading extruder. Pellets were attached to the outlet of the kneader, 3 mm ² from die to 300 mm ² hole was vacant 1 to 500 carbon atoms, after solidified in water at 10 ° C. or higher 90 ° C. below the extrusion strand form, 20 mm apart from 1mm It can be obtained by cutting and drying. The cross section of the pellet may be a circle or a polygon (triangle, quadrangle, pentagon, etc.).

Pulverization refers to making powder, flakes, granules, etc. Powdery refers to those having a size of 100 μm or less, flakes having a size exceeding 100 μm, and granular refers to the association of powders It refers to what you let me. Cellulose acylate is synthesized in a uniform solvent and solidifies when it is added to a poor solvent (water, etc.). At this time, it is powdered when it is added with strong stirring, and flaky when it is added with weak stirring. Can be. The rod-like compound is inherently powdery and may be used as it is or may be granulated. For granulation, the rod-shaped compound may be used alone or together with cellulose acylate. The method of granulating is not particularly limited, but may be granulated by adding a small amount of a solvent for dissolving them and stirring, or may be granulated by stirring while heating and slightly melting.
In these powders, the rod-like compound and the cellulose acylate are required to be mixed. Mixing may be performed anywhere before melt film formation. For example, a material that has been sufficiently stirred by a mixer or the like may be stocked once, and this may be put into a melt extruder. It may be thrown in. When melting such a powder, it is more preferable to use a biaxial melt extruder as the melt extruder.

[Melting film formation]
(1) Drying It is preferable to use the powder or pelletized by the above-mentioned method for melt film formation. Prior to film formation, the moisture content in the powder or pellet is 1% by mass or less, more preferably 0.5 mass. % Or less, it is preferable to put into the hopper of the melt extruder. At this time, based on the glass transition point (Tg) of the cellulose acylate used, the temperature of the hopper is Tg−50 ° C. or higher and Tg + 30 ° C. or lower, more preferably Tg−40 ° C. or higher and Tg + 10 ° C. or lower. It is preferable that the temperature is within a range of Tg-30 ° C. or more and Tg or less. Thereby, the re-adsorption of the water | moisture content in a hopper can be suppressed, and the said drying efficiency can be expressed more easily.

(2) Kneading and extruding The dried cellulose acylate preparation is kneaded and melted in an extruder at 120 to 250 ° C, more preferably 140 to 220 ° C, and even more preferably 150 to 200 ° C. . At this time, melting of the preparation may be performed at a constant temperature, or may be performed by being divided into several temperature regions. The kneading time is preferably 2 minutes or more and 60 minutes or less, more preferably 3 minutes or more and 40 minutes or less, and further preferably 4 minutes or more and 30 minutes or less. Furthermore, it is also preferable to carry out the inside of the melt extruder in an inert (nitrogen or the like) air flow or while evacuating using a vented extruder.

(3) Casting The molten resin is passed through a gear pump to remove the pulsation of the extruder, and then filtered through a metal mesh filter or the like, and extruded from a T-shaped die attached to the sheet onto a cooling drum. Extrusion may be performed in a single layer, or multiple layers may be extruded using a multi-manifold die or a feed block die. At this time, the thickness unevenness in the width direction can be adjusted by adjusting the distance between the lips of the die.

  Thereafter, it is extruded onto a casting drum. At this time, it is also preferable to increase the adhesion between the casting drum and the melt-extruded sheet using a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof. The casting drum is preferably 60 ° C. or higher and 160 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower, and still more preferably 80 ° C. or higher and 140 ° C. or lower.

  Next, the obtained cast film is peeled off from the casting drum, passed through a nip roll, and then wound up. The winding speed is preferably from 10 m / min to 100 m / min, more preferably from 15 m / min to 80 m / min, still more preferably from 20 m / min to 70 m / min. The film forming width is preferably 1 m or more and 5 m or less, more preferably 1.2 m or more and 4 m or less, and still more preferably 1.3 m or more and 3 m or less. The thickness of the unstretched film thus obtained is preferably 30 μm or more and 400 μm or less, more preferably 40 μm or more and 300 μm or less, and still more preferably 50 μm or more and 200 μm or less.

The obtained unstretched film is preferably trimmed at both ends and wound up. The trimmed part is pulverized, or after processing such as granulation or depolymerization / repolymerization, if necessary, as a raw material for the same type of film or as a raw material for a film of a different type It may be reused. Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding.
The sheet thus obtained is preferably trimmed at both ends and wound up. The trimmed part is recycled as a raw material for the same type of film or as a raw material for a film of a different type after being pulverized or after being subjected to a granulation process or a depolymerization / repolymerization process as necessary. May be used. Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding.

[Stretching]
The stretching is preferably performed in at least one direction (uniaxial direction) of the machine direction and the transverse direction, more preferably both the machine direction and the transverse direction. A preferable stretching temperature is Tg or more and Tg + 50 ° C. or less of cellulose acylate, more preferably Tg + 1 ° C. or more and Tg + 30 ° C. or less, and further preferably Tg + 2 ° C. or more and Tg + 20 ° C. or less. A preferable stretching ratio is preferably 10% or more and 300% or less in at least one direction (uniaxial direction), more preferably 20% or more and 250% or less, and still more preferably 30% or more and 200% or less. These stretching operations may be performed in one stage or in multiple stages. The draw ratio referred to here is determined using the following formula (8).

  Formula (8): Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching

Such stretching is performed by longitudinal stretching, lateral stretching, and combinations thereof. Longitudinal stretching: (1) Roll stretching (stretching in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side), (2) Fixed end stretching (holding both ends of the film In the longitudinal direction)
Etc. can be used.
Further transverse stretching: Tenter stretching (stretched by holding both ends of the film with a chuck and stretching it in the transverse direction (perpendicular to the longitudinal direction)),
Etc. can be used. These longitudinal stretching and lateral stretching may be performed alone (uniaxial stretching) or in combination (biaxial stretching). In the case of biaxial stretching, it may be carried out in the longitudinal and transverse sequential manners (sequential stretching) or simultaneously (simultaneous stretching).

The stretching speed of longitudinal stretching and lateral stretching is preferably 10% / min or more and 10,000% / min or less, more preferably 20% / min or more and 1000% / min or less, and further preferably 30% / min or more and 800% / min or less. It is. In the case of multistage stretching, the stretching speed refers to the average value of the stretching speed of each stage.
Following such stretching, it is also preferable to relax 0% to 10% in the longitudinal or transverse direction. Furthermore, it is also preferable to heat-set at 150 ° C. or higher and 250 ° C. or lower for 1 second or longer and 3 minutes or shorter following stretching.

Re and Rth expressed by such stretching are preferably in the above-mentioned ranges. Furthermore, as described above, it is more preferable that Rth is Re or more. Such Re and Rth are achieved by fixed end uniaxial stretching, more preferably by longitudinal and lateral biaxial stretching. That is, by stretching in the vertical and horizontal directions, the in-plane refractive index (n _md , n _td ) difference can be reduced, Re can be reduced, and further, the area magnification can be increased by extending in the vertical and horizontal directions. This is because Rth can be increased by strengthening the orientation in the thickness direction accompanying the thickness reduction.
Thus, the film thickness after extending | stretching has preferable 10-300 micrometers, More preferably, they are 20 micrometers or more and 200 micrometers or less, More preferably, they are 30 micrometers or more and 100 micrometers or less.

  Further, the angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, it is preferably as close to 0 °, preferably 0 ° ± 3 °, more preferably 0 ° ± 2 °, and further preferably 0 ° ± 1 °. In the case of transverse stretching, 90 ° ± 3 ° or −90 ° ± 3 ° is preferable, more preferably 90 ° ± 2 ° or −90 ° ± 2 °, and still more preferably 90 ° ± 1 ° or −90 ° ±. 1 °.

  These stretched or unstretched cellulose acylate films may be used alone or in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) ) Or a hard coat layer may be used.

[surface treatment]
In some cases, the cellulose acylate film may be subjected to surface treatment to improve the adhesion between the cellulose acylate film and each functional layer (for example, an undercoat layer or a back layer). For such surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment and the like can be used.

The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. Plasma-excitable gas refers to a gas that is plasma-excited under the above conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. . These are described in detail in JIII Journal of Technical Disclosure No. 2001-1745, pages 30 to 32 (issued on March 15, 2001). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev.

  Among these surface treatments, an alkali saponification treatment is particularly preferable, and is extremely effective as a surface treatment for a cellulose acylate film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the dipping method, a cellulose acylate film is passed through a tank heated to 20 ° C. to 80 ° C. in an aqueous solution of pH 10 to 14 such as NaOH or KOH over 0.1 to 10 minutes, and then neutralized. This can be achieved by washing with water and drying.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, an E-type coating method, or the like can be used. The solvent of the alkaline saponification coating solution is applied to the cellulose acylate film, so the wettability of the saponification solution is good, and the surface state is good without forming irregularities on the cellulose acylate film surface by the saponification solution solvent. It is preferred to select a solvent that remains intact. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali used in the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied, or after washing with an acid. Moreover, the coating-type saponification treatment and the alignment film coating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP-A-2002-82226 and WO02 / 46809.

  It is also preferable to provide an undercoat layer in order to improve adhesion with the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. Details of the undercoat layer are described in JIII Journal of Technical Disclosure No. 2001-1745, page 32 (issued on March 15, 2001).

  These surface treatments and undercoating steps can be incorporated at the end of the film forming step, can be performed alone, or can be performed in the functional layer application step described later.

[Functional layer]
Combining the cellulose acylate film of the present invention with the functional layer described in detail in JIII Journal of Technical Disclosure No. 2001-1745, pages 32 to 45 (issued on March 15, 2001). Is preferred. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation film), and application of an antireflection layer (antireflection film) are preferable.

(1) Application of polarizing film (preparation of polarizing plate)
[Material used for polarizing film]
Currently, a commercially available polarizing film is generally produced by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, a sulfo group, an amino group, or a hydroxyl group). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  For the substrate used for the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of these substrates include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol (PVA) and modified polyvinyl alcohol (modified PVA) described in paragraph No. [0022] of JP-A-8-338913. , Poly (N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can also be used as the polymer. Water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, PVA and modified PVA are preferred, gelatin, PVA and modified PVA are more preferred, and PVA and modified PVA are most preferred. It is particularly preferable to use two types of PVA or modified PVA having different degrees of polymerization.

  The degree of saponification of PVA is preferably in the range of 70 to 100%, more preferably in the range of 80 to 100%. The degree of polymerization of PVA is preferably in the range of 100 to 5000. The modified PVA is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of PVA and modified PVA may be used in combination.

  The thickness of the base material used for the polarizing film is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device, but the lower limit is preferably 10 μm from the viewpoint of handleability and polarizing plate durability. . Within this range, diffusion and dissipation of boric acid that crosslinks the polarizing layer due to moisture permeation does not occur, and polarization performance is maintained, which is preferable. The upper limit thereof is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.

The base material used for the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the substrate of the polarizing film, or a crosslinkable functional group may be imparted to the substrate polymer itself. Crosslinking can be performed by light, heat, or pH change, and a polarizing film substrate having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent. As for the addition amount of the crosslinking agent of a polarizing film base material, 0.1-20 mass% is preferable with respect to a base material. As a result, the orientation of the polarizing film and the moisture and heat resistance of the polarizing film are improved.
After completion of the crosslinking reaction, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance can be improved.

[Stretching of polarizing film]
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).

In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification.
More preferably, it is oblique stretching in which the film is stretched with an inclination of 10 ° to 80 ° in the oblique direction.

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), and the preferred draw ratio is 1.2 to 3.5 times, especially 1.5 to 3.0 times from the viewpoint of the above effects. is there. Thereafter, the film is dried at 50 ° C. to 90 ° C. to obtain a polarizing film.

(B) Diagonal Stretching Method For the oblique stretching method, a method of stretching using a tenter projecting in an oblique direction described in JP-A-2002-86554 can be employed. Since this stretching is performed in the air, it is preferable to make the film easy to stretch by adding water in advance. The moisture content is preferably 5% or more and 100% or less, more preferably 10% or more and 100% or less. The temperature during stretching is preferably 40 ° C. or higher and 90 ° C. or lower, and more preferably 50 ° C. or higher and 80 ° C. or lower. The humidity is preferably 50% RH to 100% RH, more preferably 70% RH to 100% RH, and still more preferably 80% RH to 100% RH. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.

After the stretching, the drying is preferably performed at 50 ° C. or more and 100 ° C. or less, more preferably 60 ° C. or more and 90 ° C. or less, preferably 0.5 minutes or more and 10 minutes or less, more preferably 1 minute or more and 5 minutes or less.
The direction of the absorption axis of the polarizing film thus obtained is preferably inclined from 10 ° to 80 ° with respect to the longitudinal direction, more preferably from 30 ° to 60 °, and still more preferably substantially. 45 ° (40 ° to 50 °).

[Lamination]
The cellulose acylate film after the saponification treatment and the polarizing film prepared by stretching are bonded together to prepare a polarizing plate. The bonding direction is preferably performed so that the casting axis direction of the cellulose acylate film and the stretching axis direction of the polarizing film are 45 °.

  The adhesive used for bonding is not particularly limited, but PVA resin (including modified PVA containing functional groups such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group), boron compound aqueous solution, and the like. Among them, PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 5 μm after drying.

  The light transmittance of the polarizing plate thus obtained is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate are 45 °. At this time, the λ / 4 plate is not particularly limited, but more preferably a plate having wavelength dependency such that the retardation becomes smaller as the wavelength becomes lower. Furthermore, it is preferable to use a polarizing plate having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(2) Application of optical compensation layer (preparation of optical compensation film)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose acylate film, and further provides an optically anisotropic layer. Is preferably formed.

[Alignment film]
An alignment film is provided on the cellulose acylate film surface-treated as described above. The alignment film has a function of defining the alignment direction of the liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film has finished its role, and thus is not necessarily an essential component of the present invention. That is, it is also possible to produce a polarizing plate by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizing film.

The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodget method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate) and the like. Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field or light irradiation is also known.
The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.

  In the present invention, in addition to the function of aligning liquid crystalline molecules, the crosslinkability of bonding side chains having crosslinkable functional groups (for example, double bonds) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, PVA and modified PVA, poly (N-methylolacrylamide), polyesters described in paragraph No. [0022] of JP-A-8-338913, for example. Polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer. Water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, PVA and modified PVA are preferred, gelatin, PVA and modified PVA are more preferred, and PVA and modified PVA are most preferred. It is particularly preferable to use two types of PVA or modified PVA having different degrees of polymerization. The degree of saponification of PVA is preferably in the range of 70 to 100%, more preferably in the range of 80 to 100%. The degree of polymerization of PVA is preferably in the range of 100 to 5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group can be determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified PVA can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxyl groups, sulfo groups, phosphono groups, amino groups, ammonium groups, amide groups, mercapto groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, and carbon atoms substituted with fluorine atoms. Examples thereof include a hydrogen group, a thioether group, a polymerizable group (unsaturated polymerizable group, epoxy group, azirinidyl group, etc.), an alkoxysilyl group (trialkoxy, dialkoxy, monoalkoxy) and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426. Can be mentioned.

  When the side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer or the crosslinkable functional group is introduced into the side chain having a function of aligning liquid crystal molecules, the alignment film polymer and optical anisotropy are obtained. The polyfunctional monomer contained in the layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation film can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  The addition amount of the crosslinking agent is preferably in the range of 0.1 to 20% by mass and more preferably in the range of 0.5 to 15% by mass with respect to the polymer. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even when the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without occurrence of reticulation can be obtained. .

  The alignment film can be basically formed by applying the polymer as an alignment film forming material on a cellulose acylate film, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be carried out at any time after coating on the cellulose acylate film. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (for example, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above. For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of the LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

In industrial implementation, this is achieved by bringing a rotating rubbing roll into contact with the film to which the polarizing film is being transported. However, the roundness, cylindricity, and deflection (bias) of the rubbing roll are achieved. The core is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. The film conveyance speed is preferably in the range of 1 to 100 m / min. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, the angle is preferably 40 to 50 °. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

  Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

  The liquid crystalline molecules used for the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disc-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which the low-molecular liquid crystals are crosslinked and no longer exhibit liquid crystallinity.

[Rod-like liquid crystalline molecules]
Examples of rod-like liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.

  Regarding rod-like liquid crystalline molecules, “Quarterly Review of Chemistry,” Volume 22, “Liquid Crystal Chemistry” (1994), Chapter 4, Chapters 7 and 11 and “Liquid Crystal Device Handbook” (Japan) There is a description in Chapter 3 of the Japan Society for the Promotion of Science 142).

  The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable group and the polymerizable group described in paragraphs [0064] to [0086] of JP-A-2002-62427 can be used. A liquid crystal compound is mentioned.

[Disc liquid crystalline molecules]
For discotic liquid crystal molecules, C.I. Benzene derivatives described in Destrade et al., “Mol. Cryst.”, 71, 111 (1981), C.I. Dextrade et al., “Mol. Cryst.”, 122, 141 (1985), “Physics lett., A”, 78, 82 (1990); Kohne et al., “Angew. Chem.”, Vol. 96, p. 70 (1984); M.M. Lehn et al., “J. Chem. Commun.”, P. 1794 (1985), J. Chem. This includes the azacrown-type and phenylacetylene-type macrocycles described in the research report “J. Am. Chem. Soc.”, 116, 2655 (1994) by Zhang et al.

  The discotic liquid crystalline molecule exhibits liquid crystallinity in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. Compounds are also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. The optically anisotropic layer formed from the discotic liquid crystalline molecules does not need to be a discotic liquid crystalline molecule finally contained in the optically anisotropic layer, for example, a low molecular discotic liquid crystalline molecule, Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or crosslinked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in JP-A 2000-155216, paragraph numbers [0151] to “0168”.

  In the hybrid alignment, the angle between the long axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases in the depth direction of the optically anisotropic layer and increases with the distance from the surface of the polarizing film, or is decreasing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. can do. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the major axis orientation direction can also be adjusted by selecting liquid crystalline molecules and additives as described above.

[Other components of optically anisotropic layer]
Along with the above liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. These components are preferably compatible with the liquid crystalline molecules and can change the tilt angle of the liquid crystalline molecules or do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer, and preferably has a copolymerizability with the above-mentioned polymerizable group-containing liquid crystal compound, for example, paragraph numbers [0018] to [0018] of JP-A-2002-296423. [0020]. The addition amount of the polymerizable monomer is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725.

  The polymer used together with the discotic liquid crystalline molecules is preferably one that can change the tilt angle of the discotic liquid crystalline molecules. Examples of such polymers include cellulose esters. Preferable examples of the cellulose ester include those described in paragraph No. [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecules so as not to inhibit the alignment of the liquid crystal molecules. Is more preferable.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a liquid crystal molecule and, if necessary, a coating liquid containing a polymerization initiator and an optional component described later on the alignment film.

  As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

  Application | coating of a coating liquid can be implemented by a well-known method (For example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

  The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystalline molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

  It is also preferable to combine this optical compensation film and a polarizing film. Specifically, for example, the optical compensation film and the polarizing film may be bonded together. Bonding can be performed in the same manner as the bonding of the cellulose acylate film and the polarizing film described in the above [bonding].

  The polarizing film is stretched so that the tilt angle of the polarizing film and the optical compensation layer matches the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. It is preferable to do. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and the stretching direction is preferably adjusted arbitrarily according to the design of the LCD.

[Liquid Crystal Display]
When the polarizing plate and the optical compensation film according to the present invention are attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
Each liquid crystal mode in which such a polarizing plate and an optical compensation film are used will be described.

[TN mode liquid crystal display]
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

[OCB mode liquid crystal display]
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper and lower portions of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in the black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate. is there.

[VA mode liquid crystal display]
The feature is that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are substantially perpendicular when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned and substantially horizontally aligned when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle. Liquid crystal cell (in MVA mode) {SID97, “Digest of Tech. Papers”, (Preliminary Proceedings) 28 (1997) 845}, (3) A rod-like liquid crystal molecule is substantially vertically aligned when no voltage is applied. , A liquid crystal cell in a mode (n-ASM mode) in which twisted multi-domain alignment is performed when a voltage is applied {described in 58-59 (1998) Preliminary Proceedings of the Japanese Liquid Crystal Symposium} and (4) SURVAI Liquid crystal cell AL mode (published in LCD International 98) includes.

[IPS mode liquid crystal display]
The feature is that the rod-like liquid crystalline molecules are oriented substantially horizontally in the plane when no voltage is applied, and this is characterized by switching by changing the orientation direction of the liquid crystal with or without voltage application. Specifically, it is described in JP-A No. 2004-365941, JP-A No. 2004-12731, JP-A No. 2004-215620, JP-A No. 2002-221726, JP-A No. 2002-55341, and JP-A No. 2003-195333. Can be used.

(Other liquid crystal display devices)
The ECB mode and the STN mode can be optically compensated based on the same concept as described above.

(3) Application of antireflection film (antireflection film)
The antireflection film generally has a low refractive index layer which is also an antifouling layer and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer) on a transparent substrate. It is provided. The cellulose acylate film of the present invention can be used for the transparent substrate.

  As a method for forming an antireflection film, a multilayer film obtained by laminating transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes is used for a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, a metal such as a metal alkoxide. A method of forming a thin film by forming a colloidal metal oxide particle film by a compound sol / gel method and then post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310), etc. Is mentioned.

  On the other hand, various antireflection films formed by laminating and applying thin films in which inorganic particles are dispersed in a matrix have been proposed as an antireflection film having high productivity. Examples of the antireflection film by such application include an antireflection film comprising an antireflection layer provided with an antiglare property, in which the surface of the uppermost layer has a fine uneven shape.

  The cellulose acylate film of the present invention can be applied to any of the above methods, but the method by coating (coating type) is particularly preferable.

[Layer structure of coating type antireflection film]
An antireflection film having a layer structure of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate is designed to have a refractive index satisfying the following relationship.
The refractive index of the high refractive index layer> the refractive index of the medium refractive index layer> the refractive index of the transparent support> the refractive index of the low refractive index layer. Each refractive index is relative.

  Further, a hard coat layer may be provided between the transparent support and the medium refractive index layer. Further, the antireflection film may comprise a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. As for such a coating type antireflection film, for example, JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706. Etc. are mentioned.

  Furthermore, each of these layers may be provided with other functions. For example, an antifouling low refractive index layer and an antistatic high refractive index layer (for example, JP-A-10-206603, 2002-243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the surface hardness of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an ultrafine particle of an inorganic compound having a high refractive index having an average particle diameter of 100 nm or less and a matrix binder. Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to make the inorganic compound into such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agent, etc .: JP-A Nos. 1-295503, 11-153703, JP-A 2000-9908 gazette; anionic compound or organometallic coupling agent: JP-A No. 2001-310432), core-shell structure having high refractive index particles as a core (JP-A No. 2001-166104 etc.), A specific dispersant may be used in combination (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002-27776069, etc.).

  Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

  Furthermore, a polyfunctional compound-containing composition containing at least two polymerizable groups of a radical polymerizable group and a cationic polymerizable group, or an organometallic compound containing a hydrolyzable group and a partial condensate thereof A composition containing at least one of the compositions is preferred as a material for forming the matrix. These are described in, for example, Japanese Patent Application Laid-Open Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

  A colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a curable film obtained from a metal alkoxide composition are also preferable as materials for forming the matrix of the high refractive index layer and the medium refractive index layer. These are described in, for example, JP-A-2001-293818.

  The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

  The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70. The thickness of the medium refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

(Low refractive index layer)
The low refractive index layer is sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55, preferably 1.30 to 1.50. The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. As a means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, and a conventionally known thin film layer means such as introduction of a silicone compound or introduction of a fluorine compound can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing a fluorine atom in a range of 35 to 80% by mass. Examples of such fluorine-containing compounds include paragraphs [0018] to [0026] of JP-A-9-222503, paragraphs [0019] to [0030] of JP-A-11-38202, Examples include the compounds described in paragraphs [0027] to [0028] of JP-A No. 2001-40284, JP-A No. 2000-284102, and the like.

  The silicone compound is a compound having a polysiloxane structure, and preferably contains a curable functional group or a polymerizable functional group in the polymer chain and has a crosslinked structure in the film. For example, reactive silicone [for example, “Silaplane” {manufactured by Chisso Corp.}, etc.], polysiloxane containing silanol groups at both ends (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of a fluorine-containing or silicon-containing polymer having a crosslinking or polymerizable group, or a polymer containing both elements is a coating composition for forming an outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating simultaneously with application or after application. A conventionally well-known thing can be used as a polymerization initiator and a sensitizer.

  A sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst is also preferable. Examples of such a cured film include a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, and Japanese Patent Laid-Open No. 58-147484). 9-157582, 11-106704, etc.), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open No. 2000-117902, 2001-2001) 48590, the compound of 2002-53804, etc.) etc. are mentioned.

  The low refractive index layer has a primary particle average diameter of 1 to 150 nm, such as fillers {e.g., silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as additives other than the above. Low refractive index inorganic compounds, organic fine particles described in JP-A No. 11-3820, paragraphs [0020] to [0038], silane coupling agents, slip agents, surfactants, and the like.

  When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer is usually provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the cellulose acylate film and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound. Specific examples of these compounds are the same as those exemplified for the high refractive index layer.

  Specific examples of the constituent components of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908 and WO00 / 46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer containing particles having an average particle size of 0.2 to 10 μm and imparting an antiglare function (antiglare function (described later)).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The hardness of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K-5400. Moreover, in the Taber test according to JIS K-5400, the smaller the amount of wear of the test piece before and after the test, the better.

(Forward scattering layer)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when the antireflection film is applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function. As the forward scattering layer, for example, Japanese Patent Application Laid-Open No. 11-38208 in which the forward scattering coefficient is specified, Japanese Patent Application Laid-Open No. 2000-199809 in which the relative refractive index of the transparent resin and the fine particles is in a specific range, and a haze value of 40% or more. The thing as described in Unexamined-Japanese-Patent No. 2002-107512 etc. which prescribed | regulated.

(Other layers)
In addition to the above layers, the antireflection film may be provided with a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like.

[Coating method]
Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US Pat. No. 2,681,294). It can form by apply | coating by the method.

[Anti-glare function]
The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently retained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Or a hard coat layer) containing relatively small particles (particle size 0.05 to 2 μm) in small amounts (0.1 to 50% by mass) to form a surface uneven film and maintaining these shapes on the surface A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, Japanese Patent Laid-Open Nos. 63-278839, 11-183710, 2000-275401) Wherein) and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by the following specific examples. The measurement method used in this example is described below.

(1) Transmission measurement YI
The cellulose acylate film of the sample was divided into 10 equal parts in the width direction, and YI of transmission measurement was measured according to the following method, and the maximum value among them was defined as YI of transmission measurement of transmission measurement.
Using a color difference meter “Z-II OPTICAL SENSOR” (manufactured by Nippon Denshoku Industries Co., Ltd.), tristimulus values X, Y, and Z by transmission measurement were measured according to JIS K-7105 6.3, and the following formula (1) ) To determine YI (value per 100 μm of sample film) of transmission measurement.
Formula (1): YI of transmission measurement = {(1.28X−1.06Z) / Y} × 100 × (100 / d)
(Here, X, Y, Z are tristimulus values measured according to 6.3 of JIS K-7105 using a color difference meter, and d is the thickness (μm) of the cellulose acylate film.)

(2) YI of reflection measurement
Samples were arbitrarily sampled 20 times from pellets which were cellulose acylate preparations, and YI of reflection measurement was measured according to the following method, and the maximum value among them was defined as YI of reflection measurement.
Using the same color difference meter used in the item (1), according to JIS K-7105 6.3, tristimulus values X, Y, Z by reflection measurement are measured, and YI of reflection measurement is obtained from the following formula (7). .
Formula (7): YI of reflection measurement = {(1.28X−1.06Z) / Y} × 100

(3) Degree of substitution of cellulose acylate The degree of acyl substitution of cellulose acylate was determined by ¹³ C-NMR according to the method described in “Carbohydr. Res.”, 273 (1995) 83-91 (Tezuka et al.). Asked.

1. Formation of Cellulose Acylate Film (1) Preparation of Cellulose Acylate Cellulose acylates with different types of acyl groups and different degrees of substitution described in Table 1 were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. After acylation, aging was performed at 40 ° C. The degree of polymerization of the cellulose acylate thus obtained was determined by the following method and listed in Table 1.

(Degree of polymerization measurement method)
About 0.2 g of completely dried cellulose acylate was precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride: ethanol = 9: 1 (mass ratio). This was measured with an Ostwald viscometer at 25 ° C. for the number of seconds to drop, and the degree of polymerization DP was determined by the following equation.

η _r = T / T ₀
[Η] = (lnη _r ) / C
DP = [η] / Km
Here, η _r is the relative viscosity, [η] is the intrinsic viscosity, T is the falling seconds (seconds) of the measurement sample (cellulose acylate solution), T ₀ is the falling seconds (seconds) of the solvent alone, and C is cellulose. Represents the concentration (g / L) of the acylate solution, and Km = 6 × 10 ⁻⁴ .

(2) Pelletization of cellulose acylate The above cellulose acylate was dried at 120 ° C. for 3 hours to give a water content of 0.1% by mass. A compound represented by the following general formula (compound is represented by each symbol) and carboxylic acid (propanoic acid, butanoic acid, pentanoic acid, hexanoic acid) were added. These addition amounts {mass ratio with respect to cellulose acylate (% or ppm)} are shown in Table 1.

Further, a plasticizer selected from the following (described in Table 1) was added, and 0.05 mass% of silicon dioxide fine particles “Aerosil R972V” was further added to all levels.
Plasticizer A: 1,4-phenylene-bisdiphenyl phosphate Plasticizer B: Triphenyl phosphate Plasticizer C: Dimethyl phthalate Plasticizer D: Dioctyl adipate

A mixture of these was put into a hopper of a twin-screw kneading extruder and kneaded at 190 ° C. with 300 rotations / minute and a residence time of 1 minute. The biaxial kneading extruder was provided with a vacuum vent and evacuated (set to 0.3 atm). After melting in this manner, it was extruded into a strand having a diameter of 3 mm, immersed in a 45 ° C. water bath for 10 seconds, passed through 10 ° C. water for 10 seconds, solidified, cut into a length of 5 mm, and pelletized. . This was dried at 100 ° C. for 10 minutes and then packaged.
The YI of the reflection measurement of the pellet thus obtained was measured by the above method and listed in Table 1.
Furthermore, blank pellets consisting only of cellulose acylate were prepared in the same manner as described above.

(3) Melt film formation Using cellulose acylate pellets to which the rod-shaped compound prepared by the above method was added, some levels were used alone, and some levels were used by mixing with blank pellets (described in Table 1). .
These pellets were dried in a vacuum dryer at 110 ° C. for 3 hours, put into a hopper adjusted to 80 ° C., melted at 190 ° C. for 5 minutes, extruded from a T-die onto a casting drum, and solidified. The temperature of the casting drum was set to Tg-10 ° C. of the film. The Tg of the film was measured by the following method.

(Tg measurement)
1) 20 mg of the film after melt film formation is sampled and placed in a DSC measurement pan.
2) This is heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (operation 1), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature is raised again from 30 ° C. to 250 ° C. (operation 2).
3) The Tg (temperature at which the baseline starts to deviate from the low temperature side) obtained in operation 2 is shown in Table 1.

The solidified film is peeled off, both ends (5% each of the total width) are trimmed immediately before winding, and then both ends are thickened (knurling) with a width of 10 mm and a height of 50 μm, and then wound at 30 m / min. It was. The width of the unstretched film thus obtained is 1.5 m at each level, and the thickness is shown in Table 2.
After continuous film formation in this way, YI of permeation measurement of an unstretched cellulose acylate film was measured by the above method and listed in Table 2.

(4) Stretching The unstretched film thus obtained was stretched at the magnifications shown in Table 2. Thereafter, trimming was performed by 5% at each end. The stretched film thus obtained was measured for YI, Re, Rth, and fluctuations in humidity by the following method and listed in Table 2. In addition, extending | stretching was implemented at 300% / min at the temperature 10 degreeC higher than Tg measured above.

(Re, Rth measurement)
After conditioning the sample film to 25 ° C. and 60% RH for 3 hours or more, using an automatic birefringence meter “KOBRA-21ADH / PR” (manufactured by Oji Scientific Instruments) at 25 ° C. and 60% RH The retardation value at a wavelength of 550 nm is measured from the direction perpendicular to the film surface and tilted by ± 40 ° from the normal to the film surface. It is calculated from the measured values in the in-plane retardation (Re), vertical direction, and ± 40 ° direction from the vertical direction. These are designated as Re ₆₀ and Rth ₆₀ .

(Humidity fluctuation of Re and Rth)
After the sample film used in the above measurement was conditioned at 25 ° C. and 10% RH for 12 hours or more, Re and Rth were measured in the same manner as described above at 25 ° C. and 10% RH (Re ₁₀ , Rth ₁₀ and To do).
Using the same sample film, after conditioning at 25 ° C. and 80% RH for 12 hours or more, Re and Rth are measured in the same manner at 25 ° C. and 80% RH as Re ₈₀ and Rth ₈₀ . ).
Re humidity fluctuation (%) and Rth humidity fluctuation (%) were calculated from the following formula.
Formula (9): Re humidity fluctuation (%) = {| Re ₁₀ −Re ₈₀ | / Re ₆₀ } × 100
Formula (10): Rth humidity fluctuation (%) = {| Rth ₁₀ −Rth ₈₀ | / Rth ₆₀ } × 100

2. Preparation of Polarizing Plate (1) Saponification of Cellulose Acylate Film An unstretched and stretched cellulose acylate film was saponified by the following 1) immersion saponification method.
1) Immersion saponification method A 1.5 mol / L aqueous solution of NaOH was used as a saponification solution.
The temperature was adjusted to 60 ° C., and the cellulose acylate film was immersed for 2 minutes.
Thereafter, the film was immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds and then passed through a water washing bath.
Although the following coating saponification method was also used, the evaluation of display unevenness incorporated in the following liquid crystal display panel showed the same results as the immersion saponification method.

2) Coating saponification 20 parts by mass of water was added to 80 parts by mass of isopropanol, and KOH was dissolved in this to 1.5 N, and the temperature was adjusted to 60 ° C. and used as a saponification solution.
This was coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute.
Thereafter, hot water at 50 ° C. was sprayed at 10 L / m ² · min for 1 minute for washing.

(2) Creation of Polarizing Layer According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and the film was stretched in the longitudinal direction.

(3) Bonding The polarizing layer obtained in this way, the saponified unstretched, stretched cellulose acylate film and the saponified “Fujitack” (unstretched triacetate film) {made by Fuji Photo Film Co., Ltd.} , PVA “PVA-117H” {manufactured by Kuraray Co., Ltd.} was used as an adhesive and bonded together in the following combinations so that the longitudinal direction of the polarizing axis and the cellulose acylate film was 45 °.
1) Polarizing plate A: Stretched cellulose acylate film / polarizing layer / unstretched cellulose acylate film 2) Polarizing plate B: Stretched cellulose acylate film / polarizing layer / "Fujitac"
3) Polarizing plate C: Stretched cellulose acylate film / polarizing layer / stretched cellulose acylate film In addition, the unstretched cellulose acylate used the film of the same level before stretching.

3. Preparation of Optical Compensation Film / Liquid Crystal Display Element The above retardation polarizing plates A, B, and C were used in place of a polarizing plate of a 15-inch display “VL-1530S” (VA method) manufactured by Fujitsu Limited. At this time, as described in Table 2, it was described as “one side” when the polarizing phase difference plate was used only on one side of the pair of polarizing plates, and “both sides” when used on both polarizing plates. Using the liquid crystal display device thus obtained, the entire display is white, and the color deviation (yellowishness) from the white paper placed next to it is visually evaluated. Then, “0” was given when the color change did not change at all, and this interval was displayed in 10 steps. The results are shown in Table 2.

  All the samples of the present invention showed good characteristics. Those outside the range of the present invention showed increased color misregistration and a value of 7 or more. In particular, the sample No. in the example of JP 2000-352620 A is disclosed. The sample of Comparative Example 9 carried out according to No. 11 had a particularly large color shift, and YI was also outside the scope of the present invention. On the other hand, Example 25 which carried out the present invention under the same conditions (although the composition ratio of the cellulose acylate is outside the more preferred range of the present invention) showed good results. Furthermore, the sample of Example 24 which made the composition of the cellulose acylate of Example 25 within the range of the more preferable composition of the present invention showed further preferable results.

  Furthermore, even when the stretched cellulose acylate film of the present invention was used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, a good optical compensation film could be produced.

  Even when the stretched cellulose acylate film of the present invention was used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, a good optical compensation film could be produced.

  Furthermore, the polarizing plate and the retardation polarizing plate of the present invention are used as a liquid crystal display device described in Example 1 of JP-A-10-48420 and a discotic liquid crystal molecule described in Example 1 of JP-A-9-26572. An optically anisotropic layer containing an alignment film, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIG. 10 of JP-A-2000-154261 When the 20-inch OCB type liquid crystal display device described in -15 is used in the IPS type liquid crystal display device shown in FIG. 11 of JP-A-2004-12731, a good liquid crystal display element free from color shift was obtained.

4). Preparation of antireflection film The stretched cellulose acylate film of the present invention was converted into an antireflection film using the stretched cellulose acylate film of the present invention in accordance with Example 47 of the Japan Society for Invention and Innovation (Publication No. 2001-1745). As a result, good optical performance was obtained.

  Further, the antireflection film of the present invention is applied to a liquid crystal display device described in Example 1 of JP-A-10-48420, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, Evaluation was made on the outermost layer of the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A-2000-154261 and the IPS type liquid crystal display device described in FIG. 11 of JP-A-2004-12731. A good liquid crystal display element was obtained.

Claims (8)

A cellulose acylate film formed by melt casting, wherein a YI (Yellowness Index) of permeation measurement obtained by the following formula (1) is 0 or more and 10 or less.
Formula (1): YI of transmission measurement = {(1.28X−1.06Z) / Y} × 100 × (100 / d)
(Here, X, Y, Z are tristimulus values measured according to 6.3 of JIS K-7105 using a color difference meter, and d is the thickness (μm) of the cellulose acylate film.) A cellulose acylate preparation for melt casting comprising at least one rod-like compound represented by the following general formula (1).
Ar ¹ -L ¹ -Ar ² (1)
(In the formula, Ar ¹ and Ar ² are each independently an aromatic group, and L ¹ is selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and combinations thereof) Divalent linking group)   The cellulose acylate preparation for melt casting according to claim 2, wherein the rod-like compound described in the general formula (1) is contained in an amount of 0.1% by mass to 40% by mass with respect to the cellulose acylate. The cellulose acylate preparation according to claim 2 or 3, wherein the substitution degree of the acyl group of cellulose acylate satisfies the following mathematical formulas (2) to (4).
Formula (2): 2.5 ≦ X + Y <3.0
Formula (3): 0 ≦ X ≦ 1.8
Formula (4): 1.0 ≦ Y <3
(In the formula, X represents the degree of substitution of the acetyl group, and Y represents the total degree of substitution of the propionyl group, butyryl group, pentanoyl group, and hexanoyl group.)   A method for producing a cellulose acylate film, comprising melting and casting the cellulose acylate preparation for melt casting according to any one of claims 2 to 4.   It is formed by casting the cellulose acylate preparation according to claim 3, and contains the rod-like compound described in the general formula (1) in an amount of 0.1% by mass to 15% by mass with respect to the cellulose acylate. The cellulose acylate film according to claim 1.   A cellulose acylate film produced by melting and casting the cellulose acylate preparation for melt casting according to any one of claims 2 to 4.   A stretched cellulose acylate film obtained by stretching the cellulose acylate film according to claim 1, at least 10% to 300% in at least a uniaxial direction.