JP2006335842A - Cellulose ester compound, cellulose ester film, method for producing the cellulose ester film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film improved in the reversible variation of retardation value due to moisture variation even in the form of a wide-width film, and to provide a polarizing plate excellent in yield, view angle characteristics and visibility and a liquid crystal display device each using the above film. <P>SOLUTION: A cellulose ester compound is provided, being a product that is obtained by reaction between the corresponding cellulose ester and a compound having a 6-22C aliphatic group and also having in the molecule either one group selected from glycidyl, isocyanate, formyl, vinylsulfone and ethyleneimine groups. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cellulose ester compound, a cellulose ester film, a method for producing a cellulose ester film, a polarizing plate, and a liquid crystal display device. More specifically, even a wide film improves reversible fluctuation of a retardation value due to humidity fluctuation. The present invention relates to a cellulose ester film, and a polarizing plate and a liquid crystal display device excellent in yield, viewing angle characteristics, and visibility using the cellulose ester film.

  In recent years, the development of thin and light notebook PCs and thin and large-screen TVs has progressed, and accordingly, the protective film for polarizing plates used in display devices such as liquid crystal display devices has become increasingly thinner, larger and higher performance. The demand for is getting stronger. Among them, the liquid crystal display device has hitherto been a problem that the viewing angle is narrow. In order to expand the viewing angle of a liquid crystal display device, a method using an optical compensation sheet has been proposed (see, for example, Patent Documents 1 to 5).

  In addition, a technique for introducing a crosslinking agent has been proposed for the purpose of preventing the polarizing plate from being broken. (For example, patent document 6.) The polarizing plate yield can be improved by these.

In addition, changes in display (contrast, color, gradation) depending on the viewing angle, particularly color changes, have been a problem, but it has been proposed to introduce a new rod-like compound. (For example, see Patent Documents 7 and 8.)
The use of the above means can improve the individual problems to some extent, but due to the increase in the size of the polarizing plate, the shrinkage force of the polarizer increases with respect to humidity fluctuation, and the cellulose ester film used as a polarizing plate protective film The phenomenon that stress is generated due to the difference from the contraction force and the variation of the retardation causes white spots and the display deterioration due to the viewing angle becomes a problem, and a technical means that can solve this problem has been demanded.

In particular, when a polarizing plate using the above-mentioned optical compensation sheet as a protective film is attached to a large panel of 17 inches or more, it has been found that a significant problem occurs. The optical compensation sheet needs not only to have a function of optically compensating the liquid crystal cell but also to be excellent in durability due to a change in use environment.
JP-A-4-229828 JP-A-4-258923 JP-A-6-75116 JP-A-6-174920 JP-A-6-222213 Japanese Patent Laid-Open No. 2001-55402 JP 2002-267847 A JP 2004-4550 A

  The object of the present invention is a cellulose ester film that has improved the reversible fluctuation of the retardation value due to humidity fluctuation, even for a wide film, and the polarizing plate yield, viewing angle characteristics, and visibility using the cellulose ester film. It is in providing the polarizing plate and liquid crystal display device which were excellent in.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
Reaction of a cellulose ester with a compound having an aliphatic group having 6 to 22 carbon atoms and having any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule A cellulose ester compound, characterized in that the product is a product obtained.

(Claim 2)
The cellulose ester compound according to claim 1, wherein the cellulose ester compound satisfies the following formula (I).

(I) 1.0 ≦ X ≦ 2.5
(However, X represents the substitution degree of the acetyl group of the cellulose ester compound)
(Claim 3)
3. A cellulose characterized in that a cellulose ester film is formed by casting a solution (dope) prepared by dissolving the cellulose ester compound according to claim 1 or 2 in an organic solvent on a support and evaporating the solvent. A method for producing an ester film.

(Claim 4)
The method for producing a cellulose ester film according to claim 3, wherein the cellulose ester film is stretched so as to have a stretching ratio of 1.02 to 1.5 times.

(Claim 5)
A cellulose ester film produced by the method for producing a cellulose ester film according to claim 3.

(Claim 6)
The cellulose ester film according to claim 5, wherein an in-plane retardation value Ro represented by the following formula (i) is 30 to 300 nm.

(I) Ro = (nx−ny) × d
(In the formula, nx and ny represent the refractive indexes in the principal axes x and y directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive indexes in the film in-plane direction. Also, d represents the thickness of the film (nm )
(Claim 7)
The cellulose ester film according to claim 5 or 6, wherein a retardation value Rt in the thickness direction represented by the following formula (ii) is 30 to 300 nm.

(Ii) Rt = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness direction of the film. (In addition, d represents the film thickness (nm).)
(Claim 8)
A polarizing plate comprising the cellulose ester film according to claim 5.

(Claim 9)
A liquid crystal display device comprising the polarizing plate according to claim 8.

  According to the present invention, even a wide film is a cellulose ester film that has improved reversible fluctuations in the retardation value due to fluctuations in humidity, and a polarizing plate yield, viewing angle characteristics, and visibility using the cellulose ester film are excellent. A polarizing plate and a liquid crystal display device can be provided.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The cellulose ester compound of the present invention has an aliphatic acyl group and an aliphatic group having 6 to 22 carbon atoms, and is any one selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group. A compound having a group covalently bonded to a residual OH group of a cellulose ester. Here, a compound having an aliphatic group having 6 to 22 carbon atoms and having any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule of the present invention. Is a compound having an aliphatic group having 6 to 22 carbon atoms and having a group that reacts with and bonds to an unreacted hydroxyl group of a cellulose ester, for example, an aldehyde compound such as a monoaldehyde represented by octyl aldehyde. The compound having a vinyl sulfone group is a compound having a vinyl group bonded to a sulfonyl group represented by ethylenesulfonyl octyl or a group capable of forming a vinyl group, and a compound having an isocyanate group or a thioisocyanate group is an octyl isocyanate. , Nonylthioisocyanate, adamantane isocyanine Monoisocyanate compounds, monothioisocyanate compounds, and compounds having a glycidyl group typified by G, cyclohexylthioisocyanate, dicyclohexylisocyanate It is a monoglycidyl ether compound. The compound having an ethyleneimine group is a monoethyleneimine compound represented by 1-phenethylaridylline and 1- (2ortholylethyl) -aridylline. By introducing these compounds into the residual OH group of the cellulose ester, it is not cross-linked, but it is made into a pendant to prevent cracking at the time of cutting due to curing of the film due to cross-linking, and a plasticizing effect by introducing an aliphatic compound As a result, the elastic modulus decreases. By reducing the elastic modulus, the stress generated on the film by the polarizer is reduced, and the occurrence of white spots is suppressed. It is also possible to improve the humidity fluctuation of the retardation value by blocking moisture uptake by blocking the OH group of the cellulose ester.

  As the addition amount of the compound having an aliphatic group having 6 to 22 carbon atoms and having any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule. Although it is not limited, the range of 0.1-10 mass% is preferable with respect to a substrate polymer from the point of the draw ratio of a film, film strength, and planarity, More preferably, it is 1-5 mass%. The molecular weight of the compound having an aliphatic group having 6 to 22 carbon atoms and having any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule is 1000. The following is desirable.

  Further, since the aliphatic compound component having 6 to 22 carbon atoms is introduced into the reactive compound, it is possible to improve the moisture permeability. The moisture permeability of the film was closely related to the deterioration of the polarizer due to moisture, and was usually addressed by the introduction of hydrophobic additives. On the other hand, it was found that the variation of the retardation value due to the environmental variation of the film, which is a problem, decreases as the film thickness decreases. However, when the film thickness is reduced, the water vapor transmission rate is reduced in proportion, and from the viewpoint of protecting the polarizer, an increase in the amount of hydrophobic additive is necessary. On the other hand, the introduction amount is limited from the viewpoint of compatibility. It was newly generated. The introduction of the additive has the effect of reducing the amount of the hydrophobic additive in achieving the necessary moisture permeability, and is very effective from the viewpoint of producing a thin protective film.

  Next, an aliphatic group having 6 to 22 carbon atoms to the hydroxyl group of cellulose and any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule In general, the substitution of the compound having dehydration includes dehydration condensation. Depending on the reactivity of the compound to be introduced, a catalyst may be used to accelerate the reaction. Examples of the catalyst include a tin complex.

  As a method for producing the cellulose ester compound of the present invention as the above-mentioned method, after once producing a cellulose fatty acid monoester or diester, the remaining hydroxyl group has the aliphatic group having 6 to 22 carbon atoms, and a glycidyl group or isocyanate. A method of introducing any one group selected from a group, a formyl group, a vinylsulfone group, and an ethyleneimine group, directly having an aliphatic group having 6 to 22 carbon atoms, and a glycidyl group, an isocyanate group, And a method of reacting any one group selected from a formyl group and a vinyl sulfone group.

  The method for producing cellulose fatty acid ester or diester is a well-known method, and any one selected from glycidyl group, isocyanate group, formyl group, and vinyl sulfone group having an aliphatic group having 6 to 22 carbon atoms. The reaction for introducing one group can be synthesized by the method described in Journal of Applied Polymer Science 58 2163-2174 (1995). Although depending on the type of the corresponding group, the reaction temperature is preferably 50 to 150 ° C., more preferably 100 to 140 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes.

  The above reaction may be carried out either without a solvent or in a solvent, but is preferably carried out using a solvent. As the solvent, dichloromethane, chloroform, tetrahydrofuran or the like can be used.

  Substitution degree of any one group selected from glycidyl group, isocyanate group, formyl group, vinylsulfone group, and ethyleneimine group having an aliphatic group having 6 to 22 carbon atoms is residual in the case of cellulose fatty acid monoester 2.0 or less, preferably 0.1 to 2.0 with respect to the hydroxyl group to be formed. In the case of cellulose fatty acid diester (cellulose diacetate), it is 1.0 or less, preferably 0.1 to 1.0, based on the remaining hydroxyl group.

  In the present invention, the cellulose as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, although the cellulose ester obtained from these can be used individually or in mixture of arbitrary ratios, it is preferable to use 50 mass% or more of cotton linters.

When the acylating agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), the cellulose ester used in the present invention is free from an organic solvent such as acetic acid or an organic solvent such as methylene chloride. It can be obtained by carrying out the reaction using a protic catalyst such as sulfuric acid. When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl, C ₆ H ₅ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Can be obtained. Specifically, it can be synthesized by the method described in JP-A-10-45804.

  In the synthesis of cellulose ester, the acyl group reacts with the hydroxyl group of the cellulose molecule. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution. For example, in cellulose triacetate, an acetyl group is bonded to all three hydroxyl groups of the glucose unit.

  The cellulose ester that can be used for the synthesis of the cellulose ester compound of the present invention is not particularly limited, but the cellulose ester satisfying the following formula (I) is preferable as the substitution degree of the acetyl group of the synthesized cellulose ester compound. Is to use.

(I) 1.0 ≦ X ≦ 2.5
(However, X represents the substitution degree of the acetyl group of the cellulose ester compound)
The substitution degree of the acyl group can be measured according to ASTM-D817-96.

  In addition to the above cellulose ester, the present invention is described in cellulose triacetate, cellulose propionate, cellulose butyrate, JP-A-10-45804, JP-A-8-231761, U.S. Pat. No. 2,319,052, and the like. It is also possible to use mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate. Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can be used by mixing with the cellulose ester according to the present invention.

  The number average molecular weight Mn (measurement method is described below) of the cellulose ester compound of the present invention is preferably in the range of 40,000 to 250,000 because the resulting film has high mechanical strength and an appropriate dope viscosity, and more preferably 45,000 to 120,000. A range is more preferred. In addition, a cellulose ester having a ratio Mw / Mn to the weight average molecular weight Mw of 1.0 to 5.0 is preferably used, and a cellulose ester of 1.5 to 4.5 is preferably used.

  The number average molecular weight of the cellulose ester can be measured under the following conditions by high performance liquid chromatography.

Solvent: Acetone Column: MPW × 1 (manufactured by Tosoh Corporation)
Sample concentration: 0.2 (mass / volume)%
Flow rate: 1.0 ml / min Sample injection volume: 300 μl
Standard sample: polymethyl methacrylate (weight average molecular weight 188,200)
Temperature: 23 ° C
In addition, the amount of metal (Ca, Mg, Fe, Na, etc.) in the cellulose ester that is used during the production of the cellulose ester or that is mixed in a small amount in the material used is preferably as small as possible, and the total content of the metal Is preferably 100 ppm or less.

  Examples of the organic solvent useful for forming a cellulose ester solution or dope in which cellulose ester is dissolved include methylene chloride, a chlorinated organic solvent (methylene chloride), which is suitable for dissolving cellulose ester, particularly cellulose triacetate. Yes.

  Non-chlorine organic solvents include, for example, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoro Ethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, Examples include 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane.

  When these organic solvents are used for cellulose triacetate, a dissolution method at room temperature can be used, but it is not possible to use a dissolution method such as a high-temperature dissolution method, a cooling dissolution method, or a high-pressure dissolution method. It is preferable because it can reduce the number of items.

  Although methylene chloride can be used for cellulose esters other than cellulose triacetate, methyl acetate, ethyl acetate, and acetone can be preferably used without using methylene chloride. Particularly preferred is methyl acetate.

  Here, hereinafter, an organic solvent having good solubility with respect to the cellulose ester is referred to as a good solvent, and has a main effect on dissolution, and an organic solvent used in a large amount among them is a main (organic) solvent or a main solvent. It is called (organic) solvent.

  The dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. These are gelling that casts the dope onto a metal support, then the solvent begins to evaporate and the ratio of alcohol increases to gel the web, making the web strong and easy to peel off from the metal support When used as a solvent or when the proportion of these is small, there is also a role of promoting dissolution of a cellulose ester of a non-chlorine organic solvent.

  Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, ethanol is preferred because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity. These organic solvents alone are not soluble in cellulose esters and are referred to as poor solvents.

  In order to obtain the effects of the present invention, it is preferable to add the following rod-like compounds to the cellulose ester film in addition to the cellulose ester compound, in order to improve the color of the display device.

  The rod-shaped compound that can be used in the present invention preferably has at least one aromatic ring, and more preferably has at least two aromatic rings. The rod-like compound preferably has a linear molecular structure. 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 degrees or more in the thermodynamically most stable structure obtained by calculation as described above. The rod-shaped compound preferably exhibits liquid crystallinity. More preferably, the rod-like compound exhibits liquid crystallinity upon heating (has thermotropic liquid crystallinity). The liquid crystal phase is preferably a nematic phase or a smectic phase.

  The rod-like compound is preferably a trans-1,4-cyclohexanedicarboxylic acid ester compound represented by the following general formula (1).

General formula (1) Ar ¹ -L ¹ -Ar ²
In formula (1), Ar ¹ and Ar ² are each independently an aromatic group. In the present 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. An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. 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 substituents for substituted aryl groups and substituted aromatic heterocyclic groups include halogen atoms (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, alkylamino groups (eg, methylamino, ethylamino) , Butylamino, dimethylamino), nitro, sulfo, carbamoyl, alkylcarbamoyl groups (eg, N-methylcarbamoyl, N-ethylcarbamoyl, N, N-dimethylcarbamoyl), sulfamoyl, alkylsulfamoyl groups (eg, N- Methylsulfamoyl, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), ureido, alkylureido groups (eg, N-methylureido, N, N-dimethylureido, N, N, N′-trimethyl) Ureido), alkyl groups (eg, methyl, ethyl, propyl, butyl, pentyl, Butyl, octyl, isopropyl, s-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), aryloxy groups (Eg, phenoxy), alkoxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, heptyloxycarbonyl), aryloxycarbo Group (eg, phenoxycarbonyl), alkoxycarbonylamino group (eg, butoxycarbonylamino, hexyloxycarbonylamino), alkylthio group (eg, methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio, octylthio), arylthio group (eg, , Phenylthio), alkylsulfonyl groups (eg, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl, octylsulfonyl), amide groups (eg, acetamide, butylamide group, hexylamide, laurylamide) and non- Aromatic heterocyclic groups (eg, morpholyl, pyrazinyl) are included.

  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 formula (1), L ¹ is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an alkynylene group, a divalent saturated heterocyclic group, —O—, —CO—, and combinations thereof. is there. 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 1-20, more preferably 1-15, still more preferably 1-10, still more preferably 1-8, 6 is most preferred.

  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 number of carbon atoms in the alkenylene group and the alkynylene group is preferably 2 to 10, more preferably 2 to 8, still more preferably 2 to 6, and still more preferably 2 to 4. Most preferred is 2 (vinylene or ethynylene). The divalent saturated heterocyclic group preferably has a 3- to 9-membered heterocyclic ring. The hetero atom of the hetero ring is preferably an oxygen atom, a nitrogen atom, a boron atom, a sulfur atom, a silicon atom, a phosphorus atom or a germanium atom. Examples of saturated heterocycles include piperidine ring, piperazine ring, morpholine ring, pyrrolidine ring, imidazolidine ring, tetrahydrofuran ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, tetrahydrothiophene ring, 1 , 3-thiazolidine ring, 1,3-oxazolidine ring, 1,3-dioxolane ring, 1,3-dithiolane ring and 1,3,2-dioxaborolane. Particularly preferred divalent saturated heterocyclic groups are piperazine-1,4-diylene, 1,3-dioxane-2,5-diylene and 1,3,2-dioxaborolane-2,5-diylene.

  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-
L-7: -O-CO-divalent saturated heterocyclic group -CO-O-
L-8: -CO-O-divalent saturated heterocyclic 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 degrees or more. As the rod-like compound, a compound represented by the following general formula (2) is more preferable.

General formula (2) Ar ¹ -L ² -XL ³ -Ar ²
In 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 for Ar ¹ and Ar ^{2 in} the formula (1).

In 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, still more preferably 1 to 4, and 1 or Most preferred is 2 (methylene or ethylene). L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the formula (2), X is 1,4-cyclohexylene, vinylene or ethynylene. Below, the specific example of a compound represented by Formula (1) is shown.

  Specific examples (1) to (34), (41), (42), (46), (47), (52), (53) are two asymmetric carbons at the 1st and 4th positions of the cyclohexane ring. Has atoms. However, the specific examples (1), (4) to (34), (41), (42), (46), (47), (52), (53) have a symmetric meso type molecular structure. Therefore, there is no optical isomer (optical activity) and only geometric isomers (trans and cis forms) exist. 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.

  Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination. The rod-shaped compound can be synthesized with reference to methods described in the literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989); Am. Chem. Soc. 113, p. 1349 (1991), p. 118, p. 5346 (1996), p. 92, p. 1582 (1970). Org. Chem. 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

  The cellulose ester film in the present invention may contain additives such as a plasticizer, an ultraviolet absorber, an antioxidant, and fine particles (mat agent).

  The plasticizer is not particularly limited, however, phosphate ester plasticizer, phthalate ester plasticizer, trimellitic ester plasticizer, pyromellitic acid plasticizer, glycolate plasticizer, citrate ester A plasticizer, a polyester plasticizer, or the like can be preferably used.

  In the cellulose ester film of the present invention, at least one plasticizer is preferably an aromatic terminal ester plasticizer represented by the following general formula (3).

General formula (3) B- (GA) n-GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (3), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the aromatic terminal ester plasticizer according to the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal There are propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the aromatic terminal ester plasticizer used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2, 2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1 , 5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl 1,3 There are hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc., and these glycols are one kind or a mixture of two or more kinds. Used as.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester used in the present invention include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Glycols can be used as one or a mixture of two or more.

  In addition, examples of the aryl glycol component having 6 to 12 carbon atoms of the aromatic terminal ester used in the present invention include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol, and the like. It can be used as a mixture of seeds or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester used in the present invention include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are each used as one or a mixture of two or more. Examples of the aryl dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The aromatic terminal ester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 2000, more preferably 500 to 1500. The acid value is preferably 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

(Acid value and hydroxyl value of aromatic terminal ester)
The acid value refers to the number of milligrams of potassium hydroxide necessary to neutralize the acid (carboxyl group present at the molecular end) contained in 1 g of the sample. The acid value and the hydroxyl value are measured according to JIS K0070.

  Hereinafter, the synthesis example of the aromatic terminal ester plasticizer used for this invention is shown.

<Sample No. 1 (Aromatic terminal ester sample)>
Into a reaction vessel, 820 parts (5 moles) of phthalic acid, 608 parts (8 moles) of 1,2-propylene glycol, 610 parts (5 moles) of benzoic acid and 0.30 parts of tetraisopropyl titanate as a catalyst are charged all at once. While stirring in an air stream, a reflux condenser was attached to reflux excess monohydric alcohol, and heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed under reduced pressure of 6.65 × 10 ³ Pa to 4 × 10 ² Pa or less at 200 to 230 ° C., followed by filtration to obtain an aromatic terminal ester having the following properties. It was.

Viscosity (25 ° C., mPa · s); 19815
Acid value: 0.4
<Sample No. 2 (Aromatic terminal ester sample)>
A sample was used except that 500 parts (3.5 moles) of adipic acid, 305 parts (2.5 moles) of benzoic acid, 583 parts (5.5 moles) of diethylene glycol, and 0.45 parts of tetraisopropyl titanate as a catalyst were used in the reaction vessel. No. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 90
Acid value: 0.05
<Sample No. 3 (Aromatic terminal ester sample)>
Except for using 570 parts (3.5 mol) of isophthalic acid, 305 parts (2.5 mol) of benzoic acid, 737 parts (5.5 mol) of dipropylene glycol and 0.40 part of tetraisopropyl titanate as a catalyst in the reaction vessel. Sample No. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 33400
Acid value: 0.2
Although the specific compound of the aromatic terminal ester plasticizer used for this invention below is shown, this invention is not limited to this.

The content of the aromatic terminal ester plasticizer used in the present invention is preferably 1 to 20% by mass, particularly preferably 3 to 11% by mass in the cellulose ester film. A preferred plasticizer is a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester used in the present invention is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  The polyhydric alcohol used in the present invention is represented by the following general formula (4).

Formula (4) R1- (OH) n
In the formula, R1 represents an n-valent organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic or phenolic hydroxyl group.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for the polyhydric alcohol ester used for this invention, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. The use of acetic acid is preferred because the compatibility with the cellulose ester is increased, and it is also preferred to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid. Examples of preferable alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids possessed by them, or derivatives thereof. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The specific compound of a polyhydric alcohol ester is shown below.

  The cellulose ester film according to the present invention preferably contains a plasticizer other than the plasticizer.

  By including two or more plasticizers, elution of the plasticizer can be reduced. The reason is not clear, but it seems that elution is suppressed by the ability to reduce the amount added per type and the interaction between the two plasticizers and the cellulose ester.

  Other plasticizers that can be used in the present invention include the following.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate and the like can be used.

  These plasticizers can be used alone or in admixture of two or more. 1-20 mass% is preferable with respect to a cellulose ester, and, as for the usage-amount of a plasticizer, 4-16 mass% is still more preferable, Especially preferably, it is 6-11 mass%. If the amount of the plasticizer added is too large, the film becomes too soft and the rate of decrease in elastic modulus due to heat increases. If the amount added is too small, the moisture permeability of the film decreases.

  As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of preferably used ultraviolet absorbers include, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, condensed polycyclic compounds, nickel complex compounds, and the like. However, it is not limited to these. Moreover, the polymeric ultraviolet absorber described in JP-A-6-148430 is also preferably used.

  Specific examples of ultraviolet absorbers useful in the present invention include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butyl). -Phenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butyl) -Phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methyl-phenyl) benzotriazole, 2 , 2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy -3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methyl-phenol (TINUVIN 171), 2-octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [ Mixture of 3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN 109), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (tinuvin 326) But it can be, but are not limited to these. Moreover, any of the above-mentioned tinuvins such as tinuvin 109, tinuvin 171 and tinuvin 326 are commercially available products manufactured by Ciba Specialty Chemicals, Inc., and can be preferably used.

  Specific examples of the benzophenone compounds include 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy- 5-benzoylphenylmethane) and the like, but are not limited thereto. Examples of the polycyclic fused ring compound include, but are not limited to, pyrene, benzoylnaphthalene, xylidiylnaphthalene, and the like.

  In addition, the ultraviolet absorber that can be used for the cellulose ester film of the present invention is described in Japanese Patent Application No. 11-295209 because it has little contamination in the plasma treatment process and is excellent in the coating properties of various coating layers. It is preferable to include an ultraviolet absorber having a distribution coefficient of 9.2 or more, and it is particularly preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

  Moreover, the polymeric ultraviolet absorber (or ultraviolet-absorbing polymer) described in JP-A-6-148430 and Japanese Patent Application No. 2000-156039 can be preferably used. High molecular weight ultraviolet absorbers described in general formula (1), general formula (2) of JP-A-6-148430, or general formulas (3), (6) and (7) of Japanese Patent Application No. 2000-156039 are particularly preferably used. .

  As the antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1 , 3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadec -3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) ) -Isocyanurate and the like. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

  It is preferable that fine particles are added to the cellulose ester film of the present invention.

  As fine particles to be added, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, silicic acid. Mention may be made of aluminum, magnesium silicate and calcium phosphate. Among them, those containing silicon are preferable because the turbidity is low and the haze of the film can be reduced, and silicon dioxide is particularly preferable.

  In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such particles are preferable because they can reduce the haze of the film. Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes and the like.

  The silicon dioxide fine particles can be obtained, for example, by burning a mixture of vaporized silicon tetrachloride and hydrogen at 1000 to 1200 ° C. in the air.

  The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. The average diameter of the primary particles is more preferably 5 to 16 nm, and further preferably 5 to 12 nm. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is more preferably 90 to 200 g / L or more, and still more preferably 100 to 200 g / L or more. Higher apparent specific gravity makes it possible to prepare a high-concentration fine particle dispersion, which is preferable because no haze or aggregates are generated. In the present invention, the liter is represented by L.

The amount of fine particles added is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and still more preferably 0.08 to 0.16 g per 1 m ^{2 of} the cellulose ester film. Thereby, a convex part of 0.1-1 μm is preferably formed on the surface of the cellulose ester film that is three-dimensionally cross-linked by the cross-linking agent.

  As preferable fine particles of silicon dioxide, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) manufactured by Nippon Aerosil Co., Ltd. Commercially available products can be mentioned, and Aerosil 200V, R972, R972V, R974, R202, R812 can be preferably used. The fine particles of zirconium oxide are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and any of them can be used.

  Among these, Aerosil 200V, Aerosil R972V, and Aerosil TT600 are particularly preferable because they have a large effect of lowering the turbidity and lowering the friction coefficient of the cellulose ester film of the present invention.

  Examples of polymer fine particles include silicone resin, fluorine resin, and acrylic resin. Of these, silicone resins are preferred, and those having a three-dimensional network structure are particularly preferred. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.) Can be mentioned.

  In the measurement of the primary average particle diameter of the fine particles, the particles are observed with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), 100 particles are observed, and the average value is used as the primary average particle diameter. I can do it.

  The apparent specific gravity described above can be calculated by the following formula by measuring a weight of a predetermined amount of silicon dioxide fine particles in a graduated cylinder and measuring the weight.

Apparent specific gravity (g / L) = silicon dioxide mass (g) / volume of silicon dioxide (L)
Moreover, it is preferable that a cellulose-ester film is what was made by solution casting film forming. In particular, the dope is cast on a support, dried after peeling, and stretched 1.00 to 1.2 times in the width direction when the residual solvent amount is 3 to 40% by mass, and further dried. It is preferable that it is the obtained cellulose-ester film.

  Hereinafter, the method for producing a cellulose ester film according to the present invention will be described. The cellulose ester film according to the present invention is preferably produced by a solution casting film forming method.

  Dissolving step: dissolving the cellulose ester, the reactive compound according to the present invention, additives, etc. in an organic solvent mainly composed of a good solvent for cellulose ester (flaked) while stirring to form a dope It is a process or a process of forming a dope by mixing a reactive compound solution, an additive solution or the like according to the present invention into a cellulose ester solution. For dissolution of the cellulose ester, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557, Alternatively, various dissolution methods such as a method of cooling and dissolving as described in JP-A-9-95538 and a method of performing at high pressure as described in JP-A-11-21379 can be used. A method in which a solution in which an ester and the reactive compound are dissolved is heated in a sealed container at a temperature of 80 ° C. or higher, and particularly preferably performed at 100 ° C. or higher. It is also preferable to carry out the pressurization. The above means can not only improve the solubility of the cellulose ester, but also thermally condense the reactive compound to residual hydroxyl groups of the cellulose ester. The concentration of the cellulose ester in the dope is preferably 10 to 35% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Casting process: Metal such as an endless metal belt, such as a stainless steel belt or a rotating metal drum, in which the obtained dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) This is a step of casting the dope from the pressure die slit to the casting position on the support. A pressure die that can adjust the slit shape of the die base and facilitates uniform film thickness is preferred. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is preferable to obtain the cellulose-ester film of a laminated structure by the co-casting method which casts several dope simultaneously.

  Solvent evaporation step: heating the web (referred to as the dope film after casting the dope on the metal support as the web) on the metal support, and removing the solvent until the web becomes peelable from the metal support It is a process of evaporating. In order to evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. However, the drying efficiency is preferable. A method of combining them is also preferable. In the case of backside liquid heat transfer, it is preferable to heat at or below the boiling point of the main solvent of the organic solvent used in the dope or the organic solvent having the lowest boiling point.

  Peeling step: A step of peeling the web where the solvent has evaporated on the metal support at the peeling position. The peeled web is sent to the next process. In addition, if the residual solvent amount (the following formula) of the web at the time of peeling is too large, peeling is difficult, or conversely, if the film is peeled off after being sufficiently dried on the metal support, a part of the web is in the middle. It may come off.

  Here, there is a gel casting method (gel casting) as a method for increasing the film forming speed (the film forming speed can be increased by peeling while the residual solvent amount is as large as possible). For example, there are a method in which a poor solvent for cellulose ester is added to the dope and the gel is formed after casting the dope, a method in which the temperature of the metal support is lowered and gelled. By gelling on a metal support and increasing the strength of the film at the time of peeling, peeling can be accelerated and the film forming speed can be increased. The web can be peeled in the range of 5 to 150% by mass depending on the strength of the web on the metal support, the length of the metal support, etc. If it is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes due to the peeling tension are liable to occur. Therefore, the residual solvent amount at the time of peeling is determined in consideration of the economic speed and quality. In this invention, it is preferable that the temperature in the peeling position on this metal support body shall be 10-40 degreeC, and it is more preferable to set it as 15-30 degreeC. Moreover, it is preferable that the residual solvent amount of the web in this peeling position shall be 10-120 mass%. The amount of residual solvent can be represented by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the mass M is dried at 110 ° C. for 3 hours.

  Drying and stretching step: After peeling, use a drying device that alternately conveys the web through a plurality of rolls arranged in the drying device and / or a tenter device that clips and conveys both ends of the web with a clip. dry. In the present invention, the cellulose stealth film is preferably stretched by 1.02 to 1.5 times, and as the method, it is preferably stretched using a tenter device. More preferably, it is biaxially stretched in biaxial directions perpendicular to each other, such as in the vertical and horizontal directions.

  The film thickness fluctuation of the film obtained by stretching in the biaxial direction perpendicular to each other can be reduced. When the film thickness variation of the cellulose ester film is too large, the retardation becomes uneven, and problems such as coloring occur when used as an optical compensation film. The film thickness variation of the cellulose ester film is preferably ± 3%, more preferably ± 1%. For the purposes as described above, a method of stretching in the biaxial directions perpendicular to each other is effective, and the stretching ratios in the biaxial directions perpendicular to each other are 1.02 to 1.5 times and 1.02 to 1.5, respectively. The range can be doubled, and particularly preferably 1.02 to 1.3 times and 1.02 to 1.3 times, respectively.

  There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  The cellulose ester film of the present invention has a retardation value Rt in the film thickness direction represented by the following formulas (i) and (ii) of 20 to 300 nm and an in-plane retardation value Ro of 20 to 300 nm. It is particularly preferable that Rt is 70 to 200 nm and Ro is 30 to 100 nm.

(I) Ro = (nx−ny) × d
(Ii) Rt = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness direction of the film. (In addition, d represents the film thickness (nm).)
The retardation values (Ro) and (Rt) can be measured using an automatic birefringence meter. For example, it can be obtained at a wavelength of 590 nm using KOBRA-21ADH (Oji Scientific Instruments) under an environment of 23 ° C. and 55% RH.

  The film obtained as described above is preferably 2% by mass or less, and more preferably 0.4% by mass or less in terms of the residual solvent amount of the final finished film, in order to obtain a film having good dimensional stability.

  As a drying means, hot air is generally blown on both sides of the web, but there is also a means for heating by applying a microwave instead of the wind. Too much drying tends to impair the flatness of the finished film. Throughout, the drying temperature is usually in the range of 40 to 250 ° C. The drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used. In this invention, after forming a film by solution casting film formation, it is preferable to set a drying temperature in the range of 100-125 degreeC at a drying process, Most preferably, it is 115-125 degreeC. When the temperature is set higher than 125 ° C., the retardation value decreases, and when it is 100 ° C. or lower, the dimensional stability of the film over time deteriorates. The heat treatment is preferably performed in the range of 1 hour or more and 5 hours or less from the viewpoint of stably obtaining the effects of the present invention and productivity.

Further, the transmittance of the cellulose ester film is preferably 90% or more, more preferably 92% or more, and particularly preferably 94% or more. Moreover, it is preferable that the haze of a cellulose-ester film is 0 to 1%, and it is especially preferable that it is 0 to 0.1%. In the cellulose ester film of the present invention, the moisture permeability is preferably 250 g / m ² · 24 hours or less, more preferably 0 to 220 g / m ² · 24 hours, particularly 1 to 200 g / m. ² · 24 hours is preferable. If the moisture permeability is too low, the evaporation rate of moisture contained in an adhesive such as an aqueous polyvinyl alcohol solution is slowed when bonding with a polarizer, but the cellulose ester film itself has moisture permeability and water absorption. Therefore, there is no big problem in the present invention.

  Moreover, it is preferable that what is called a knurling part is provided in the edge part of the optical film of this invention. In particular, the height of the knurling is preferably 25% or less of the film thickness of the cellulose ester film, and the stability in storage of the roll film is improved by providing the knurling part.

(Polarizer)
The polarizing plate of the present invention will be described. A conventionally well-known thing can be used as a polarizer used for the polarizing plate of this invention. For example, a film made of a hydrophilic polymer such as polyvinyl alcohol is treated with a dichroic dye such as iodine and stretched, or a plastic film such as vinyl chloride is treated and oriented. The polarizer thus obtained is bonded with a cellulose ester film. At this time, at least one of the cellulose ester films needs to use the cellulose ester film of the present invention, but the cellulose triacetate (TAC) film that has been conventionally used as a support for polarizing plates is used. Although it may be used for bonding of other polarizer surfaces, in order to obtain the effect described in the present invention to the maximum, all constituting the polarizing plate in terms of the same physical properties of both surfaces of the polarizing plate protective film The cellulose ester film of the present invention is preferably used as the cellulose ester film.

  Furthermore, the light transmission axis of a polarizer containing a dichroic substance and the stretching direction in the width direction during casting of an optically biaxial cellulose ester film to be bonded to the polarizer are substantially parallel. The angles formed by the respective axes are preferably within ± 10 °, preferably within ± 3 °, and more preferably within ± 1 °.

  Furthermore, at the time of producing the polarizing plate, a polarizer containing a dichroic substance and an optically biaxial cellulose ester film are bonded together, but from the viewpoint of improving production efficiency, it was produced as a long roll. A cellulose ester film is preferably used. In the present invention, the long length indicates 500 m or more, preferably 1000 m or more, and particularly preferably 1000 m to 4000 m.

  In view of the recent increase in the size of liquid crystal displays, the width of the polarizer protective film is preferably 1 m or more. On the other hand, if it exceeds 4 m, the apparatus becomes large and difficult to convey, so the width of the cellulose ester film of the present invention is preferably 1 to 4 m, particularly preferably 1.4 to 2 m. According to the present invention, even with a film having a width of 1.4 m or more, the effects of the present invention can be obtained uniformly over the entire width of the film.

(Liquid crystal display device)
The liquid crystal display device of the present invention is a liquid crystal display device having the polarizing plate of the present invention and a liquid crystal cell, wherein the cellulose ester film according to the present invention contains the dichroic substance of the polarizing plate and the liquid crystal In order to obtain the effects of the present invention, it is preferable to arrange them between the cells.

  By incorporating the polarizing plate of the present invention into a liquid crystal display device, the liquid crystal display device of the present invention having various visibility can be produced. The cellulose ester film and polarizing plate of the present invention are various drive systems such as reflective, transmissive, transflective LCD or TN, STN, OCB, HAN, VA (PVA, MVA) and IPS. It is preferably used in LCDs. In particular, a large-screen display device having a screen of 30 or more types, particularly 30 to 54 types, has no white spots at the periphery of the screen, and the effect is maintained for a long period of time. In particular, the MVA liquid crystal display device has a remarkable effect. Is recognized. In addition, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even during long viewing.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<< Production of cellulose ester compound >>
<< Production of Cellulose Ester Compound 1 >>
7 g (0.056 mol) of hexane isocyanate, 12.3 g (0.05 mol) of cellulose acetate and 50 ml of tetrahydrofuran were dissolved in 200 ml of three-headed Kolben equipped with a condenser, a stirrer and a thermometer. After dissolution, 0.1 g of dibutyltin laurate was added and heated to reflux for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 50 ml of dichloromethane was added, and then slowly dropped into 1000 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is designated as cellulose ester compound 1. The yield was 16 g (87%), and the substitution degree of acetyl group was determined by NMR and found to be 0.9.

<< Production of Cellulose Ester Compound 2 >>
Glycidyl octyl ether (7.9 g, 0.056 mol), cellulose diacetate (12.3 g, 0.05 mol), and tetrahydrofuran (50 ml) were dissolved in 200 ml of three-headed Kolben equipped with a condenser, a stirrer, and a thermometer. After dissolution, 0.1 g of dibutyltin oxide was added and heated to reflux for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 50 ml of dichloromethane was added, and then slowly dropped into 1000 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is designated as cellulose ester compound 2. The yield was 17 g (88%), and the substitution degree of the acetyl group was determined by NMR and found to be 0.9.

<< Production of Cellulose Ester Compound 3 >>
Ethylenesulfonyl octyl (11 g, 0.056 mol), cellulose diacetate (12.3 g, 0.05 mol), and tetrahydrofuran (50 ml) were added to 200 ml of three-headed Kolben equipped with a condenser, a stirrer, and a thermometer, and dissolved. After dissolution, 0.1 g of dibutyltin oxide was added and heated to reflux for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 50 ml of dichloromethane was added, and then slowly dropped into 1000 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is designated as cellulose ester compound 3. Yield 17 g (86%). As a result of obtaining the substitution degree of the acetyl group by NMR, it was 0.9.

<< Preparation of Cellulose Ester Compound 4 >>
To 200 ml of three-headed Kolben equipped with a condenser, a stirrer, and a thermometer, 8.6 g (0.056 mol) of octylaridiline, 12.3 g (0.05 mol) of cellulose acetate and 50 ml of tetrahydrofuran were added and dissolved. After dissolution, 0.1 g of butyltin oxide was added and heated to reflux for 5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 50 ml of dichloromethane was added, and then slowly dropped into 1000 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is referred to as cellulose ester compound 4. The yield was 16 g (86%), and the degree of substitution of the acetyl group determined by NMR was 0.88.

<< Production of Cellulose Ester Compound 5 >>
Octane isocyanate 17 g (0.11 mol), cellulose acetate 20.4 g (0.1 mol), and tetrahydrofuran 100 ml were dissolved in a 300 ml three-headed Kolben equipped with a condenser, a stirrer, and a thermometer. After dissolution, 0.1 g of dibutyltin laurate was added and heated to reflux for 8 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and after adding 100 ml of dichloromethane, it was slowly added dropwise to 2000 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is designated as cellulose ester compound 5. The yield was 47 g (92%), and the substitution degree of acetyl group was determined by NMR.

<< Production of Cellulose Ester Compound 6 >>
1300 g (0.11 mol) of glycidyl hexyl ether, 20.4 g (0.1 mol) of cellulose acetate, and 100 ml of tetrahydrofuran were dissolved in 300 ml of three-headed Kolben equipped with a condenser, a stirrer, and a thermometer. After dissolution, 0.1 g of dibutyltin oxide was added and heated to reflux for 8 hours. After completion of the reaction, the reaction solution was cooled to room temperature, 50 ml of dichloromethane was added, and then slowly dropped into 1500 ml of methanol with stirring to cause reprecipitation. The resulting precipitate was filtered and dried. The dried product was again placed in 1000 ml of methanol, washed with stirring, filtered and dried to obtain the desired product. The obtained product is designated as cellulose ester compound 6. The yield was 44 g (89%), and the substitution degree of acetyl group was determined by NMR.

<< Production of cellulose ester film >>
<Preparation of fine particle dispersion>
Fine particles 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Preparation of fine particle additive solution>
Cellulose ester resin A was added to a dissolution tank containing methylene chloride and heated to completely dissolve, and this was then added to Azumi filter paper No. 3 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244. The fine particle dispersion was slowly added thereto while sufficiently stirring the filtered cellulose ester solution. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

(Particulate additive solution composition)
Methylene chloride 99 parts by weight Cellulose ester resin A 4 parts by weight Fine particle dispersion 11 parts by weight <Preparation of main dope liquid>
Methylene chloride and ethanol were added to the pressure dissolution tank. Next, cellulose ester resin A (cellulose ester compound 1), plasticizers (A) and (B), and ultraviolet absorbers (A), (B) and (C) were heated and mixed and dissolved at 70 ° C. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

(Main dope solution composition)
Methylene chloride 300 parts by mass Ethanol 57 parts by mass Cellulose ester resin A 100 parts by mass Plasticizer (A) 9.5 parts by mass Plasticizer (B) 2.2 parts by mass UV absorber (A) 0.5 part by mass UV absorber (B) 0.6 parts by mass Ultraviolet absorber (C) 0.6 parts by mass In addition to 100 parts by mass of the main dope solution and 2 parts by mass of the fine particle additive solution, an in-line mixer (Toray static type in-tube mixer Hi- Mixer, SWJ) were mixed well, and then the endless belt casting apparatus was used to uniformly cast the dope solution on a stainless steel belt support at a temperature of 33 ° C. and a width of 1.5 m. The temperature of the stainless steel belt was controlled at 25 ° C. On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

  The peeled cellulose ester film was stretched 1.3 in the width direction using a tenter while applying heat at 120 ° C to 130 ° C. The residual solvent at the start of stretching was 30%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 120 ° C., the drying time was 2 hours, and the transport tension was changed between 150 and 350 N / m.

  As described above, a cellulose ester film 101 having a thickness of 80 μm and a knurling width of 1.5 m, an end portion having a width of 1 cm, and a height of 8 μm was obtained.

  The cellulose ester films 102 to 107 of the present invention and the cellulose ester of the comparative example were used in the same manner as described above except that the materials shown in Table 1 were used and the main dope composition and stretching conditions were changed as shown in Table 2. A film 201 was produced.

  In addition, to the cellulose ester film 107, 3 parts by mass of the exemplified rod-like compound (10) was added to the main dope solution. In addition, aromatic terminal ester sample No. of plasticizer D. 3 was prepared by the method for synthesizing the aromatic terminal ester.

<Production of polarizing plate>
A polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizing film.

  Subsequently, according to the following processes 1-5, the polarizing film and the produced said cellulose-ester films 101-107, 201 and the cellulose-ester film of the back side polarizing plate protective film were bonded together, and the polarizing plate was produced. As the polarizing plate protective film on the back side, a cellulose ester film (Konica Minolta Tack KC8UX: manufactured by Konica Minolta Opto Co., Ltd.) having no retardation was used as a polarizing plate.

  Step 1: Soaked in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain a saponified cellulose ester film on the side to be bonded to the polarizer.

  Step 2: The polarizing film was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

  Step 3: Excess adhesive adhered to the polarizing film in Step 2 was gently wiped off, and this was placed on the cellulose ester film treated in Step 1 and laminated.

Process 4: The produced cellulose ester film laminated in the process 3, the polarizing film, and the cellulose ester film on the back side were bonded at a pressure of 20 to 30 N / cm ² and a conveying speed of about 2 m / min.

  Process 5: The sample which bonded the polarizing film produced in the process 4 and the cellulose-ester film in the 80 degreeC dryer was dried for 2 minutes, and the polarizing plate was produced. Polarizing plates 101 to 107 and 201 were produced using cellulose ester films 101 to 107 and 201, respectively.

<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

  The polarizing plates on both sides of the Fujitsu 15-type display VL-150SD that had been bonded in advance were peeled off, and the prepared polarizing plates 101 to 107 and 201 were bonded to the glass surfaces of the liquid crystal cells.

  At that time, the produced cellulose ester films 101 to 107 and 201 are disposed between the polarizer and the liquid crystal cell, and the direction of bonding of the polarizing plate is the same direction as that of the previously bonded polarizing plate. The liquid crystal display devices 101 to 107 and 201 were each manufactured so that the absorption axis was directed to the above.

  The following evaluation was performed using the cellulose ester films 101 to 107 and 201, the polarizing plates 101 to 107 and 201, and the liquid crystal display devices 101 to 107 and 201 obtained as described above.

<Evaluation items and evaluation methods>
(Elastic modulus)
The produced cellulose ester film was conditioned at 23 ° C. and 55% RH for 24 hours, and the elastic modulus was measured according to the method described in JIS K7127. Tensilon RTA-100 manufactured by Orientec Co., Ltd. was used as the tensile tester. The shape of the test piece was No. 1 type test piece, and the test speed was 100 mm / min. The elastic modulus was calculated at an elastic modulus analysis start point of 2 MPa and an elastic modulus analysis end point of 60 MPa.

(Retardation value fluctuation due to humidity change)
The retardation value by each humidity of the produced cellulose-ester film was calculated | required, respectively, and Rt (a) was calculated | required from the value.

  The Rt (a) fluctuation is as follows: Rt (b) is conditioned at 23 ° C. and 20% RH for 5 hours, and then the Rt value measured in the same environment is measured as Rt (b), where Rt (c) is After the same film was continuously conditioned at 23 ° C. and 80% RH for 5 hours, the Rt value measured in the same environment was determined and this was defined as Rt (c), and Rt (a) was determined from the following equation.

Rt (a) = | Rt (b) −Rt (c) |
Furthermore, the humidity-controlled sample was measured again in an environment of 23 ° C. and 55% RH, and it was confirmed that this change was a reversible change.

  Table 3 shows the retardation value variation with respect to the elastic modulus and humidity. It can be seen that the films 101 to 107 of the present invention have a low elastic modulus and a small variation in retardation value with respect to humidity change, and the effect of the present invention is higher than that of the comparative example.

  That is, it is shown that the film has a large improvement effect against physical property-related failures such as contrast fluctuation due to humidity fluctuation and corner unevenness due to humidity fluctuation.

<Polarizing plate yield>
Failures and troubles in the polarizing plate manufacturing process were evaluated in three stages. From the results of Table 4, the polarizing plate of the present invention had few failures and troubles in the polarizing plate production process, and was excellent in yield.

◎: No wrinkles, bends or scratches are generated in the manufacturing process of the polarizing plate ○: Almost no wrinkles, bends or scratches are generated in the manufacturing process of the polarizing plate ×: Many wrinkles, bends and scratches occur during the manufacturing process of polarizing plate. <Deterioration of viewing angle>
The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. Subsequently, the viewing angle of the produced liquid crystal display device (commercial panel + self-made elliptical polarizing plate) was measured in an environment of 23 ° C. and 20% RH, and further 23 ° C. and 80% RH, and evaluated according to the following criteria. Finally, a viewing angle measurement was performed again in an environment of 23 ° C. and 55% RH, and it was confirmed that the change during the measurement was a reversible fluctuation. These measurements were made after the liquid crystal display device was placed in the environment for 5 hours.

◎: No viewing angle variation ○: Little viewing angle variation △: Viewing angle variation is observed ×: Viewing angle variation is very large << Evaluation of visibility >>
About each produced said liquid crystal display device, after leaving for 100 hours on 60 degreeC and 90% RH conditions, it returned to 23 degreeC and 55% RH. As a result, when the surface of the display device was observed, the one using the cellulose ester film of the present invention was excellent in flatness, whereas the comparative display device was observed for a long time because fine wavy unevenness was observed. And my eyes were easy to get tired.

A: No wavy unevenness is observed on the surface. O: A slight wavy unevenness is observed on the surface. Δ: A slight wavy unevenness is slightly observed on the surface. X: A fine wavy unevenness is observed on the surface. Is shown in Table 4.

  It turns out that the cellulose-ester films 101-107 of this invention have a favorable deflection | deviation plate yield, and the liquid crystal display devices 101-107 using the same have a favorable viewing angle deterioration and visibility.

Claims (9)

Reaction of a cellulose ester with a compound having an aliphatic group having 6 to 22 carbon atoms and having any one group selected from a glycidyl group, an isocyanate group, a formyl group, a vinylsulfone group, and an ethyleneimine group in the molecule A cellulose ester compound, characterized in that the product is a product obtained. The cellulose ester compound according to claim 1, wherein the cellulose ester compound satisfies the following formula (I).
(I) 1.0 ≦ X ≦ 2.5
(However, X represents the substitution degree of the acetyl group of the cellulose ester compound) 3. A cellulose characterized in that a solution (dope) prepared by dissolving the cellulose ester compound according to claim 1 or 2 in an organic solvent is cast on a support, and the solvent is evaporated to form a cellulose ester film. A method for producing an ester film. The method for producing a cellulose ester film according to claim 3, wherein the cellulose ester film is stretched so as to have a stretching ratio of 1.02 to 1.5 times. A cellulose ester film produced by the method for producing a cellulose ester film according to claim 3. The cellulose ester film according to claim 5, wherein an in-plane retardation value Ro represented by the following formula (i) is 30 to 300 nm.
(I) Ro = (nx−ny) × d
(In the formula, nx and ny represent the refractive indexes in the principal axes x and y directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive indexes in the film in-plane direction. Also, d represents the thickness of the film (nm ) The cellulose ester film according to claim 5 or 6, wherein a retardation value Rt in the thickness direction represented by the following formula (ii) is 30 to 300 nm.
(Ii) Rt = ((nx + ny) / 2−nz) × d
(In the formula, nx, ny, and nz represent the refractive indexes in the principal axis x, y, and z directions of the refractive index ellipsoid, respectively, and nx and ny represent the refractive index in the film in-plane direction, and nz represents the thickness direction of the film. (In addition, d represents the film thickness (nm).) A polarizing plate comprising the cellulose ester film according to claim 5. A liquid crystal display device comprising the polarizing plate according to claim 8.