JP2009132764A - Cellulose derivative, cellulose derivative film, and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose derivative film having a high retardation Rth in the thickness direction. <P>SOLUTION: The film contains a cellulose derivative which has a polymerization unit represented by the general formula (1) and which satisfies the following expressions (I)-(III); (I) 0≤DS<SB>A</SB>≤1.4, (II) 0<DS<SB>B</SB>, and (III) 0<DS<SB>C</SB>. In the formula (1), R<SP>2</SP>, R<SP>3</SP>, and R<SP>6</SP>each independently represent a hydrogen atom, an unsubstituted aliphatic hydrocarbon group, or an acyl group. In the expressions, DS<SB>A</SB>is the number of hydrogen atoms present as R<SP>2</SP>, R<SP>3</SP>, and R<SP>6</SP>in the unit, DS<SB>B</SB>is the number of unsubstituted aliphatic hydrocarbon groups each present as R<SP>2</SP>, R<SP>3</SP>, and R<SP>6</SP>in the unit, and DS<SB>C</SB>is the number of acyl groups each present as R<SP>2</SP>, R<SP>3</SP>, and R<SP>6</SP>in the unit, wherein DS<SB>A</SB>+DS<SB>B</SB>+DS<SB>C</SB>=3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tough cellulose derivative film having a large retardation Rth in the thickness direction, an optical compensation sheet, a polarizing plate and a liquid crystal display device using the same. The present invention also relates to a novel cellulose derivative useful for producing a film.

Cellulose acylate films have been widely used as polarizing plate protective films for liquid crystal display devices because of their moderate water permeability and high optical isotropy (low retardation value).
In recent years, a method has been proposed in which a phase difference is imparted to a cellulose acylate film so as to have an optical compensation function in addition to a function as a polarizing plate protective film. For example, Patent Document 1 discloses a method in which a triazine type compound having high planarity is added to cellulose acylate to develop retardation.
Patent Documents 2 and 3 each disclose an optical film satisfying predetermined optical properties containing a cellulose mixed ester having two or more different substituents, and the optical film production method includes predetermined conditions. Discloses a method of stretching treatment.

  On the other hand, there are few examination examples of optical film use regarding cellulose derivatives other than cellulose acylate. For example, Patent Document 4 proposes an optical film made of cellulose ether acetate that satisfies a predetermined condition.

JP 2003-170492 A JP 2002-71957 A JP 2005-8803 A JP 2005-283997 A

An object of the present invention is to provide a cellulose derivative film having a large retardation Rth in the thickness direction, an optical compensation sheet using the same, a polarizing plate, and a liquid crystal display device.
Another object of the present invention is to provide a novel cellulose derivative that has good film-forming properties and is useful for producing a film.

一般式（１）
［式中、Ｒ²、Ｒ³及びＲ⁶は、それぞれ独立に水素原子、無置換の脂肪族炭化水素基又はアシル基を表す。］
（Ｉ） ０≦ＤＳ_A≦１．４
（II） ０＜ＤＳ_B
（III） ０＜ＤＳ_C
［式中、ＤＳ_Aは、上記単位中にＲ²、Ｒ³及びＲ⁶として存在する水素原子の数であり、ＤＳ_Bは、同単位中にＲ²、Ｒ³及びＲ⁶としてそれぞれ存在する無置換の脂肪族炭化水素基の数であり、及びＤＳ_Cは、同単位中にＲ²、Ｒ³及びＲ⁶としてそれぞれ存在するアシル基の数であり、ＤＳ_A＋ＤＳ_B＋ＤＳ_Cは３である。］ Means for solving the above problems are as follows.
[1] A film comprising a cellulose derivative containing a polymer unit represented by the following general formula (1) and satisfying the following mathematical formulas (I) to (III).

General formula (1)
[Wherein, R ² , R ³ and R ⁶ each independently represents a hydrogen atom, an unsubstituted aliphatic hydrocarbon group or an acyl group. ]
(I) 0 ≦ DS _A ≦ 1.4
(II) 0 <DS _B
(III) 0 <DS _C
[Wherein DS _A is the number of hydrogen atoms present as R ² , R ³ and R ⁶ in the unit, and DS _B is present as R ² , R ³ and R ^{6 in} the same unit, respectively. Is the number of unsubstituted aliphatic hydrocarbon groups, and DS _C is the number of acyl groups present as R ² , R ³ and R ^{6 in} the same unit, respectively, and DS _A + DS _B + DS _C is 3 is there. ]

[2] The film of [1], wherein the cellulose derivative satisfies the following formula (IV).
(IV) DS _C ≦ DS _B
[3] The film of [1], wherein the cellulose derivative satisfies the following formulas (I) ′ to (III) ′.
(I) ′ 0 ≦ DS _A ≦ 0.4
(II) ′ 1.5 ≦ DS _B ≦ 2.7
(III) ′ 0.1 ≦ DS _C ≦ 1.5
[4] The film according to any one of [1] to [3], wherein the acyl group of the cellulose derivative is an aromatic acyl group.
[5] An optical compensation sheet comprising the film of any one of [1] to [4] or having the film of any one of [1] to [4].
[6] A polarizing plate comprising a polarizer and the film of any one of [1] to [4].
[7] A liquid crystal display device comprising the film according to any one of [1] to [4].

［式中、Ｒ²、Ｒ³及びＲ⁶は、それぞれ独立に水素原子、無置換の脂肪族炭化水素基又はアシル基を表す。］
（Ｉ） ０≦ＤＳ_A≦１．４
（II） ０＜ＤＳ_B
（III） ０＜ＤＳ_C
［式中、ＤＳ_Aは、上記単位中にＲ²、Ｒ³及びＲ⁶として存在する水素原子の数であり、ＤＳ_Bは、同単位中にＲ²、Ｒ³及びＲ⁶としてそれぞれ存在する無置換の脂肪族炭化水素基の数であり、及びＤＳ_Cは、同単位中にＲ²、Ｒ³及びＲ⁶としてそれぞれ存在するアシル基の数であり、ＤＳ_A＋ＤＳ_B＋ＤＳ_Cは３である。］ [8] A cellulose derivative comprising a polymer unit represented by the following general formula (1) and satisfying the following mathematical formulas (I) to (III).

[Wherein, R ² , R ³ and R ⁶ each independently represents a hydrogen atom, an unsubstituted aliphatic hydrocarbon group or an acyl group. ]
(I) 0 ≦ DS _A ≦ 1.4
(II) 0 <DS _B
(III) 0 <DS _C
[Wherein DS _A is the number of hydrogen atoms present as R ² , R ³ and R ⁶ in the unit, and DS _B is present as R ² , R ³ and R ^{6 in} the same unit, respectively. Is the number of unsubstituted aliphatic hydrocarbon groups, and DS _C is the number of acyl groups present as R ² , R ³ and R ^{6 in} the same unit, respectively, and DS _A + DS _B + DS _C is 3 is there. ]

[9] The cellulose derivative according to [8], which satisfies the following formula (IV):
(IV) DS _C ≦ DS _B
[10] The cellulose derivative according to [8] or [9], which satisfies the following formulas (I) ′ to (III) ′.
(I) ′ 0 ≦ DS _A ≦ 0.4
(II) ′ 1.5 ≦ DS _B ≦ 2.7
(III) ′ 0.1 ≦ DS _C ≦ 1.5
[11] The cellulose derivative according to any one of [8] to [10], wherein the acyl group is an aromatic acyl group.

The cellulose derivative of the present invention has good film forming properties and is useful for producing optical films and the like. In particular, since the expression of retardation Rth in the thickness direction during film formation is high, it is particularly useful for producing a film exhibiting high Rth.
Therefore, by using the cellulose derivative of the present invention, it is possible to provide a film having a large Rth suitable for use as an optical film for liquid crystal display devices, particularly as an optical compensation sheet.
Further, by using the film of the present invention as a protective film for a polarizing plate, an optical compensation function can be added to the polarizing plate without increasing the number of components of the polarizing plate.
The optical compensation sheet of the present invention and the polarizing plate using the optical compensation sheet of the present invention as a protective film are useful for liquid crystal display devices, particularly VA mode and OCB mode liquid crystal display devices.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the present invention will be described in detail. Hereinafter, typical embodiments of the present invention will be described, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Further, in this specification, the term “cellulose derivative” is used to include both a cellulose compound and a compound having a cellulose skeleton obtained by introducing a functional group biologically or chemically using cellulose as a raw material.

［式中、Ｒ²、Ｒ³及びＲ⁶は、それぞれ独立に水素原子、無置換の脂肪族炭化水素基又はアシル基を表す。］
（Ｉ） ０≦ＤＳ_A≦１．４
（II） ０＜ＤＳ_B
（III） ０＜ＤＳ_C [Cellulose derivative]
In the present invention, the hydroxyl groups at the 2-position, 3-position and 6-position of the β-glucose ring which is a structural unit of cellulose are substituted with an ether substituent and an ester substituent, and the degree of substitution of the substituent satisfies a specific relationship. It relates to a cellulose derivative. Specifically, the present invention relates to a cellulose derivative having a polymer unit represented by the following general formula (1) and satisfying the following mathematical formulas (I) to (III).

[Wherein, R ² , R ³ and R ⁶ each independently represents a hydrogen atom, an unsubstituted aliphatic hydrocarbon group or an acyl group. ]
(I) 0 ≦ DS _A ≦ 1.4
(II) 0 <DS _B
(III) 0 <DS _C

In the formulas (I) to (III), DS _A is the number of hydrogen atoms present as R ² , R ³ and R ⁶ in the unit, and DS _B is R ² , R ^{3 in the} same unit. And R ⁶ are the number of unsubstituted aliphatic hydrocarbon groups respectively present, and DS _C is the number of acyl groups present as R ² , R ³ and R ^{6 in} the same unit, respectively. That is, DS _A is the ratio in which the hydroxyl groups at the 2-position, 3-position and 6-position are unsubstituted, and DS _B is the substitution of the unsubstituted aliphatic hydrocarbon group for the hydroxyl groups at the 2-position, 3-position and 6-position. And DS _C is the degree of substitution of the acyl group for the hydroxyl groups at the 2nd, 3rd and 6th positions. Therefore, DS _A + DS _B + DS _C is 3.
In order to form a cellulose derivative, the hydrogen atom of the hydroxyl group needs to be substituted to some extent. On the other hand, cellulose derivatives in which the hydrogen atom of the hydroxyl group is substituted only with an acyl group, such as cellulose triacetate, which is a conventional cellulose derivative, have good film-forming properties, but have low Rth expression, such as an Rth enhancer. If an additive is not added separately, a film showing a high Rth cannot be obtained. In the present invention, by forming a cellulose derivative in which a hydrogen atom of a hydroxyl group is substituted with an acyl group and an unsubstituted aliphatic hydrocarbon group, the film forming property is good, and Rth expression during film forming is good Of high cellulose derivatives.

The higher the DS _B , that is, the degree of substitution with an unsubstituted aliphatic hydrocarbon group, the higher the Rth expression of the cellulose derivative. Therefore, it is preferable to use a cellulose derivative that satisfies the following formula (IV) for production of a film that requires high Rth.
(IV) DS _C ≦ DS _B
On the other hand, the aliphatic hydrocarbon group degree of substitution DS _B becomes high to easily water tend to whitening during film. Also, the film strength tends to decrease. Therefore, it is preferable to use a cellulose derivative that satisfies all of the following formulas (I) ′ to (III) ′ for production of a film that requires high Rth and also requires high transparency and film strength. ,
(I) ′ 0 ≦ DS _A ≦ 0.4
(II) ′ 1.5 ≦ DS _B ≦ 2.7
(III) ′ 0.1 ≦ DS _C ≦ 1.5
Furthermore, it is preferable to use a cellulose derivative that satisfies all of the following formulas (I) "to (III)".
(I) ”0 ≦ DS _A ≦ 0.2
(II) ”1.7 ≦ DS _B ≦ 2.7
(III) ”0.1 ≦ DS _C ≦ 1.3

DS _A , DS _B and DS _C are obtained by using the method described in Cellulose Communication 6, 73-79 (1999) and Chrality 12 (9), 670-674, ¹ H-NMR or ¹³ C-NMR. Can be determined.

In the above formula (I), the unsubstituted aliphatic hydrocarbon group represented by R ² , R ³ and R ⁶ is an aliphatic group containing no atoms other than carbon atoms and hydrogen atoms, and is linear or branched. And any of cyclic groups. The unsubstituted aliphatic hydrocarbon group is preferably an unsubstituted alkyl group, and more preferably an unsubstituted linear alkyl group. The unsubstituted aliphatic hydrocarbon group preferably has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 6 carbon atoms, and a linear alkyl group having the above-mentioned range. Is more preferable. Of these, a methyl group and an ethyl group are particularly preferable.

In the formula (I), the acyl groups represented by R ² , R ³ and R ⁶ may be either an aliphatic acyl group or an aromatic acyl group. It may have both of the aliphatic acyl group and aromatic acyl group, in which case, DS _C is the sum of the substitution degree of aliphatic acyl groups and aromatic acyl groups.
The aliphatic acyl group refers to a group in which R of — (C═O) R is an aliphatic group. The aliphatic group site may be any of linear, branched and cyclic aliphatic groups. 1-20 are preferable, as for the carbon atom number of an aliphatic acyl group, 1-12 are more preferable, and 1-6 are more preferable.
The aromatic acyl group refers to a group in which R of — (C═O) R is an aromatic group. Aromatic is defined as an aromatic compound in the physics and chemistry dictionary (Iwanami Shoten) 4th edition, page 1208, and the aromatic group in the present invention may be an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably It is an aromatic hydrocarbon group.
The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12, and most preferably 6 to 10. Specific examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, a terphenyl group, and the like, and more preferably a phenyl group. As the aromatic hydrocarbon group, a phenyl group, a naphthyl group, and a biphenyl group are particularly preferable. As the aromatic heterocyclic group, those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferable. Specific examples of the heterocycle include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline. , Isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. As the aromatic heterocyclic group, a pyridyl group, a triazinyl group, and a quinolyl group are particularly preferable.

The aliphatic group part and the aromatic group part of the aliphatic acyl group and the aromatic acyl group may have one or more substituents. The substituent can be selected from the substituent T listed below.
Substituent T:
An alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12, more preferably 2 to 8). For example, a vinyl group, an allyl group, a 2-butenyl group, a 3-pentenyl group, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 2 carbon atoms). 8, for example, propargyl group, 3-pentynyl group, etc.), aryl group (preferably having 6 to 30 carbon atoms, more preferred) Is 6 to 20, particularly preferably 6 to 12, and examples thereof include a phenyl group, a biphenyl group, a naphthyl group, and the like, an amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10, and particularly preferably). Is 0-6, for example, an amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dibenzylamino group, etc., an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms). And particularly preferably 1 to 8, for example, methoxy group, ethoxy group, butoxy group and the like, and aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 and particularly preferably 6 to 6). 12 such as a phenyloxy group and a 2-naphthyloxy group), an acyl group (preferably having 1 to 20 carbon atoms, More preferably, it is 1-16, Most preferably, it is 1-12, for example, an acetyl group, a benzoyl group, a formyl group, a pivaloyl group etc. are mentioned, An alkoxycarbonyl group (preferably C2-C20, More preferably 2 to 16, particularly preferably 2 to 12, for example, methoxycarbonyl group, ethoxycarbonyl group and the like, and aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably Is 7 to 10, for example, a phenyloxycarbonyl group, etc.), an acyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms such as an acetoxy group, A benzoyloxy group, etc.), an acylamino group (preferably having 2 carbon atoms) -20, more preferably 2-16, particularly preferably 2-10, for example, acetylamino group, benzoylamino group and the like, alkoxycarbonylamino group (preferably having 2-20 carbon atoms, more preferably 2 to 16, particularly preferably 2 to 12, and examples thereof include a methoxycarbonylamino group and the like, an aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 and particularly preferably 7). -12, such as phenyloxycarbonylamino group), sulfonylamino group (preferably 1-20 carbon atoms, more preferably 1-16, particularly preferably 1-12, for example methanesulfonylamino) Group, benzenesulfonylamino group, etc.), sulfamoyl group ( The number of carbon atoms is preferably 0 to 20, more preferably 0 to 16, particularly preferably 0 to 12, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group. Carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, and phenylcarbamoyl group). ), An alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, and examples thereof include a methylthio group and an ethylthio group), an arylthio group (preferably having a carbon atom number). 6-20, more preferably 6-16, particularly preferably 6-12, examples A phenylthio group, etc.), a sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as mesyl group and tosyl group), sulfinyl A group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as methanesulfinyl group and benzenesulfinyl group), ureido group (preferably having 1 carbon atom) To 20, more preferably 1 to 16, particularly preferably 1 to 12, and examples thereof include a ureido group, a methylureido group, and a phenylureido group), a phosphoric acid amide group (preferably having 1 to 20 carbon atoms, More preferably, it is 1-16, Most preferably, it is 1-12, for example, diethyl phosphoric acid amide, phenylphosphoric acid amide Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group , An imino group, a heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, an imidazolyl group and a pyridyl group. Group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 3 carbon atoms). 30, particularly preferably 3 to 24, such as trimethylsilyl group and triphenylsilyl group. And the like).
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

The aliphatic acyl group is preferably unsubstituted, and among them, an acetyl group, a propionyl group, and a butyryl group are preferable.
The aromatic acyl group preferably does not have a substituent containing a carboxyl group (—C (═O) O—). If it contains a carboxyl group, the hydrophilicity increases and the humidity dependence of the optical properties tends to deteriorate. In the aromatic acyl group, the aromatic moiety is preferably unsubstituted or substituted with an alkyl group or an aryl group. Preferred examples of the aromatic acyl group include benzoyl group, phenylbenzoyl group, 4-methylbenzoyl, 4-heptylbenzoyl group, 2,4,5-trimethoxybenzoyl group, 3,4,5-trimethoxybenzoyl group. And naphthoyl groups.
Note that it is preferable that the acyl group is an aromatic acyl group because Rth expression is further improved.

  The cellulose derivative of the present invention can be produced by referring to a known method, for example, a method described in “Encyclopedia of Cellulose” pages 131 to 164 (Asakura Shoten, 2000). Specifically, cellulose using, as a raw material, cellulose ether in which a part of hydroxyl groups at the 2nd, 3rd and 6th positions are substituted with an ether group, and using an acid chloride or an acid anhydride as a raw material in the presence of a base such as pyridine. A known raw material can be used for the ether raw material cotton.

  The average degree of polymerization of the cellulose derivative of the present invention is preferably 15 to 5000, more preferably 50 to 5000, and still more preferably 50 to 4000. By increasing the degree of polymerization, crystallization during film formation can be suppressed. On the other hand, when the degree of polymerization is too large, there is a problem that the viscosity at the time of preparing the dope becomes too high.

[Cellulose derivative film]
The present invention also relates to a film containing the cellulose derivative. The film of the present invention preferably contains 50% by mass or more, and more preferably 70% by mass or more, of the cellulose derivative in the total components (solid content). By containing in the said range, the property of the cellulose derivative of this invention can be used effectively, and it becomes a film which shows high Rth. The film of this invention may contain the additive with the said cellulose derivative in the range which does not impair the effect of this invention depending on necessity. Hereinafter, various additives that can be added to the film of the present invention will be described.
(Plasticizer)
A plasticizer can be added to the film of the present invention in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred.
The amount of the plasticizer added is preferably 0.1 to 25% by mass of the amount of the cellulose derivative, more preferably 1 to 20% by mass, and still more preferably 3 to 15% by mass.

(UV absorber)
The film of the present invention may contain an ultraviolet absorber.
Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like, but less benzotriazole compounds Compounds are preferred. Further, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, and polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used. When the film of the present invention is used as a protective film for a polarizing plate, the ultraviolet absorber is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and has a liquid crystal display property from the viewpoint of preventing the deterioration of a polarizer and liquid crystal. In view of the above, those that absorb less visible light having a wavelength of 400 nm or more are preferable.

  Specific examples of the benzotriazole ultraviolet absorber useful in the present invention include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t -Butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl Phenyl) -5-chlorobenzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2 -Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-3'-t-butyl-5) '-Methylph Nyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3- [3-t-butyl-4 -Hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole- Examples include, but are not limited to, mixtures of 2-yl) phenyl] propionate.

In addition, as commercial products, “TINUVIN 109”, “TINUVIN 171”, “TINUVIN 326”, “TINUVIN 328” {all trade names, Ciba Specialty Chemicals Co., Ltd. )} Can be preferably used.
The addition amount of the ultraviolet absorber is preferably 0.1 to 5.0% by mass and more preferably 0.5 to 5.0% by mass with respect to the cellulose derivative.

(Deterioration inhibitor)
A degradation inhibitor (for example, an antioxidant, a peroxide decomposer, a radical inhibitor, a metal deactivator, an acid scavenger, an amine) may be added to the film of the present invention. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 to 1 of the solution (dope) to be prepared from the viewpoint that the effect of addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferable that it is mass%, and it is further more preferable that it is 0.01-0.2 mass%. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

(Matting agent fine particles)
It is preferable to add fine particles as a matting agent to the film of the present invention. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Can be mentioned. Among these fine particles, those containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 1 nm to 20 nm and an apparent specific gravity of 70 g / liter or more. The average diameter of the primary particles is preferably 1 nm to 20 nm, and a smaller one of 5 nm to 16 nm is more preferable because it can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter, more preferably 100 to 200 g / liter. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.05 to 2.0 μm, and these fine particles are present in the film as aggregates of primary particles, and 0.05 to 2.0 on the film surface. An unevenness of 2.0 μm is formed. The secondary average particle size is preferably 0.05 μm to 1.0 μm, more preferably 0.1 μm to 0.7 μm, and still more preferably 0.1 μm to 0.4 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. Also, 200 particles are observed at different locations, and the average value is taken as the average particle size.

  As the silicon dioxide fine particles, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, Nippon Aerosil Co., Ltd., trade name) may be used. it can. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the haze of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

  The matting agent is preferably prepared by the following method. That is, a fine particle dispersion prepared by stirring and mixing a solvent and fine particles is prepared in advance, and this fine particle dispersion is separately added to a first additive solution having a cellulose derivative concentration of less than 5% by mass and a molecular weight of 200 to 2000, and stirring and dissolving. After that, a method of further adding the second additive solution, stirring and dissolving, and further mixing with the main cellulose derivative dope solution is preferable.

  Since the surface of the matting agent is hydrophobized, when a hydrophobic additive is added, the additive is adsorbed on the surface of the matting agent, and aggregates of the additive tend to be generated using this as a nucleus. After mixing a relatively hydrophilic additive in advance with the matting agent dispersion, by mixing the hydrophobic additive, aggregation of the additive on the surface of the matting agent can be suppressed, and the haze is low. It is preferable because light leakage in black display when incorporated in a liquid crystal display device is small.

  It is preferable to use an in-line mixer for mixing the matting agent dispersant and the additive solution and mixing the cellulose derivative dope liquid. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. A mass% is even more preferable. A higher dispersion concentration is preferable because the turbidity with respect to the same amount of addition becomes low, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose derivative dope solution is preferably 0.001 to 1.0% by mass, more preferably 0.005 to 0.5% by mass, and 0.01 to 0.1% by mass. % Is even more preferred.

[Production of cellulose derivative film]
The film of the present invention is preferably produced by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which a cellulose derivative is dissolved in an organic solvent.

The organic solvent used for the preparation of the dope is an ether having 3 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms, an ester having 3 to 12 carbon atoms, and a halogenated carbonization having 1 to 6 carbon atoms. It is preferable to include a solvent selected from hydrogen.
The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone, and ester (that is, —O—, —CO—, and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms is preferably within the above-described preferable number of carbon atoms range of the solvent having any functional group.

Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.

Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is still more preferably 40 to 60 mol%. Methylene chloride is a representative halogenated hydrocarbon.

  For the preparation of the dope, it is preferable to use a mixed solvent of methylene chloride and alcohol, and the ratio of alcohol to methylene chloride is preferably 1 to 50% by mass, more preferably 10 to 40% by mass, and more preferably 12 to 30% by mass. Further preferred. As the alcohol, methanol, ethanol, and n-butanol are preferable, and two or more kinds of alcohols may be mixed and used.

  The dope can be prepared by a general method under a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared by using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent.

  The concentration of the cellulose derivative in the dope is preferably 10 to 40% by mass, and more preferably 10 to 30% by mass. Various additives described above may be added to the organic solvent (main solvent).

The dope can be prepared by stirring a cellulose derivative and an organic solvent at room temperature (0 to 40 ° C.). The high concentration solution may be stirred under pressure and heating conditions. Specifically, the cellulose derivative and the organic solvent are sealed in a pressure vessel, and stirred while heating to a temperature not lower than the boiling point of the solvent at room temperature and in a range where the solvent does not boil under pressure.
The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

  Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.

  When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.

  It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.

  Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or is taken out and then cooled using a heat exchanger or the like.

  A solution can also be prepared by a cooling dissolution method. In the cooling dissolution method, the cellulose derivative can be dissolved in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can melt | dissolve a cellulose derivative with a normal melt | dissolution method, there exists an effect that a uniform solution can be obtained rapidly according to a cooling melt | dissolution method.

  In the cooling dissolution method, first, a cellulose derivative is gradually added to an organic solvent at room temperature while stirring. The amount of the cellulose derivative is preferably adjusted so as to be contained in the mixture in an amount of 10 to 40% by mass. The amount of the cellulose derivative is more preferably 10 to 30% by mass. Furthermore, you may add the arbitrary additive mentioned later in a mixture.

  Next, the mixture is cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, still more preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). The mixture of the cellulose derivative and the organic solvent is solidified by cooling.

  The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and even more preferably 12 ° C./min or more. The faster the cooling rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling to the final cooling temperature.

  Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., and still more preferably 0 to 50 ° C.), the cellulose derivative is dissolved in the organic solvent. The temperature may be increased by simply leaving it at room temperature or in a warm bath.

  The heating rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more, and even more preferably 12 ° C./min or more. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is the value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating until the final heating temperature is reached. is there.

  A uniform solution is obtained as described above. If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be determined by merely observing the appearance of the solution with the naked eye.

  In the cooling dissolution method, it is preferable to use an airtight container in order to avoid moisture mixing due to condensation during cooling. In the cooling and heating operation, when the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to perform pressurization and pressure reduction, it is preferable to use a pressure-resistant container.

  A cellulose derivative film is produced from the prepared cellulose derivative solution (dope) by a solvent cast method.

  The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. The surface of the drum or band is preferably finished in a mirror state. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.

  The drying method in the solvent cast method is described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,2078, 2,429,297, 2,429,978, 2,607,704, 2,273,069, and 2,739,070. Each specification, British Patent Nos. 640731 and 736892, and Japanese Patent Publication Nos. 45-4554, 49-5614, JP-A-60-176634, 60-203430, and 62- There is a description in each publication of No. 115035. Drying on the band or drum can be performed by blowing an inert gas such as air or nitrogen.

  Using the prepared cellulose derivative solution (dope), two or more layers can be cast to form a film. In this case, it is preferable to produce a cellulose derivative film by a solvent cast method. The dope is cast on a drum or band and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is in the range of 10 to 40%. The surface of the drum or band is preferably finished in a mirror state.

  When casting a plurality of cellulose derivative liquids of two or more layers, it is possible to cast a plurality of cellulose derivative solutions, and cellulose derivatives from a plurality of casting openings provided at intervals in the traveling direction of the support. A film may be produced while casting and laminating solutions each containing. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be used. Moreover, it can also be formed into a film by casting a cellulose derivative solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-61-104413, JP-A-61-158413, and JP-A-6-134933. The method described in the publication can be used. Furthermore, a method for casting a cellulose derivative film described in JP-A-56-162617, which wraps a flow of a high-viscosity cellulose derivative solution with a low-viscosity cellulose derivative solution and simultaneously extrudes the high- and low-viscosity cellulose derivative solution. It can also be used.

  In addition, after peeling off the film formed on the support by the first casting port using the two casting ports, the second casting is performed on the side of the film that is in contact with the support surface. Thus, a film can also be produced. For example, the method described in Japanese Patent Publication No. 44-20235 can be mentioned.

  As the cellulose derivative solution to be cast, the same solution may be used, or different cellulose derivative solutions may be used. In order to give a function to a plurality of cellulose derivative layers, a cellulose derivative solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose derivative solution used in the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorption layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a cellulose derivative solution having a high concentration and a high viscosity in order to obtain a necessary film thickness. In that case, the stability of the cellulose derivative solution is poor and solids are generated, which often causes problems such as defects and poor flatness. As a solution to this problem, by casting a plurality of cellulose derivative solutions from the casting port, it is possible to extrude a highly viscous solution onto the support at the same time. Not only can it be produced, but also the use of a concentrated cellulose derivative solution can achieve a reduction in drying load and increase the production speed of the film.

(Extension process)
The stretched cellulose derivative film of the present invention may be stretched in the film transport direction (longitudinal direction) and / or in the direction perpendicular thereto (width direction).

Methods for stretching in the width direction are described in, for example, JP-A-62-115035, JP-A-4-152125, 4-284221, 4-298310, and 11-48271. Yes. In the case of stretching in the longitudinal direction, for example, the film is stretched by adjusting the speed of the film transport roller so that the film winding speed is higher than the film peeling speed. In the case of stretching in the width direction, the film can also be stretched by conveying while holding the width of the film with a tenter and gradually widening the width of the tenter. After the film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
In order to improve Re developability as well as Rth developability, it is particularly preferable to stretch in both the transport direction and the width direction.

[Characteristics of cellulose derivative film]
The film of this invention is manufactured so that the characteristic may become a preferable range according to various uses. Below, the characteristic preferable in using the film of this invention as a member of a liquid crystal display device is demonstrated.
(Film thickness)
The thickness of the cellulose derivative film of the present invention is preferably 30 μm to 200 μm. More preferably, they are 40 micrometers-150 micrometers, More preferably, they are 40 micrometers-100 micrometers.

(Film retardation)
The cellulose derivative film of the present invention has high expression of retardation, particularly retardation in the thickness direction. Specifically, the retardation Rth (589) in the thickness direction at a wavelength of 589 nm is preferably 50 nm to 1000 nm, and more preferably 100 nm to 800 nm, when the film thickness is 100 μm.
On the other hand, the in-plane retardation Re (589) at a wavelength of 589 nm of the cellulose derivative film of the present invention is preferably 0 nm to 280 nm, and more preferably 0 nm to 200 nm.

  In the present specification, Re and Rth represent front retardation and retardation in the thickness direction, respectively. Re is measured by making light with a wavelength of 589 nm incident in the normal direction of the film in KOBRA 21ADH (trade name, manufactured by Oji Scientific Instruments). Rth is a letter measured by making light with a wavelength of 589 nm incident from a direction inclined + 40 ° with respect to the film normal direction with the slow axis of the front (determined by KOBRA 21ADH) as the tilt axis (rotation axis). 3 directions of retardation value and retardation value measured by making light with a wavelength of 589 nm incident from a direction inclined by −40 ° with respect to the normal direction of the film with the in-plane slow axis as the tilt axis (rotation axis) KOBRA 21ADH is calculated based on the retardation value measured in (1). Here, as the assumed value of the average refractive index, the values of “Polymer Handbook” (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose derivative (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59). KOBRA 21ADH calculates nx, ny, and nz by inputting these assumed values of average refractive index and film thickness.

(Wavelength dependence of retardation)
The cellulose derivative film of the present invention is characterized in that retardation, particularly Rth, has a small wavelength dependency. The film of the present invention can achieve a fluctuation of Rth within 5% with respect to the absolute value of Rth of 589 nm with respect to light in the visible light range.

(Haze)
The cellulose derivative film of the present invention preferably has a value measured using, for example, a haze meter (1001DP type, trade name, manufactured by Nippon Denshoku Industries Co., Ltd.) of 0.1 to 0.8. More preferably, it is 0.1-0.7, More preferably, it is 0.1-0.60. By controlling the haze within the above range, a high-contrast image can be obtained when incorporated in a liquid crystal display device as an optical compensation sheet.

(Equilibrium moisture content of film)
The water absorption rate of the cellulose derivative film can be evaluated by measuring the equilibrium water content at a constant temperature and humidity. The equilibrium moisture content is calculated by measuring the moisture content of the sample that has reached equilibrium after being left at a constant temperature and humidity for 24 hours by the Karl Fischer method, and dividing the moisture content (g) by the sample mass (g). .
It is preferable that the equilibrium moisture content in the cellulose derivative film of this invention in 25 degreeC80% RH is 3.5 mass% or less. More preferably, it is 3.0 mass% or less, More preferably, it is 2.5 mass% or less.
By setting the equilibrium moisture content of the film within the above range, the change in retardation of the film can be reduced.

(Retardation change due to environmental humidity)
The cellulose derivative film of the present invention preferably has a small change in change retardation due to environmental humidity, and Re and Rth preferably satisfy the relationship of the following formulas (7) and (8).

であり、よりさらに好ましくは、

である。 Formula (7) is more preferably

And even more preferably

It is.

であり、よりさらに好ましくは、

である。 Further, the formula (8) is more preferably

And even more preferably

It is.

  By controlling the retardation change due to the environmental humidity within the above range, a liquid crystal display device having a small tint change due to the environmental humidity when incorporated in the liquid crystal display device can be obtained.

(Surface failure)
The cellulose derivative film of the present invention has, for example, a value obtained by sampling the cellulose derivative film and counting the number of foreign matters or aggregates of 30 μm or more present on both ends 30 cm width and length 1 m of the obtained film. 50 is preferable. More preferably, it is 0-40, Most preferably, it is 0-30.

(Surface treatment of cellulose derivative film)
A surface treatment may be applied to the cellulose derivative film. Examples of the surface treatment include saponification treatment, plasma treatment, flame treatment, and ultraviolet irradiation treatment. Saponification treatment includes acid saponification treatment and alkali saponification treatment. Plasma treatment includes corona discharge treatment and glow discharge treatment. In order to maintain the flatness of the film, in these surface treatments, the temperature of the cellulose derivative film is preferably set to a glass transition temperature (Tg) or lower, specifically 150 ° C. or lower. The surface energy of the cellulose derivative film after these surface treatments is preferably 55 to 75 mN / m.
The glow discharge treatment may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.133 Pa to 2.67 kPa), and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is 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, and tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). 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, alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose derivative film.

  The alkali saponification treatment is preferably carried out by a method of directly immersing the cellulose derivative film in a saponification solution tank or a method of applying a saponification solution to the cellulose derivative film. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. 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 of 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 at the time of 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 with water or with an acid and then with water.

  The surface energy of the solid obtained by these methods can be determined by the contact angle method, the wet heat method, and the adsorption method as described in “Basics and Applications of Wetting” (Realize, 1989.12.10). it can. In the case of the cellulose derivative film of the present invention, it is preferable to use a contact angle method. Specifically, two types of solutions having known surface energies are dropped on a cellulose derivative film, and at the intersection between the surface of the droplet and the film surface, the angle formed by the tangent line drawn on the droplet and the film surface The surface angle of the film can be calculated by defining the angle containing the droplet as the contact angle.

  By carrying out the above-mentioned surface treatment on the cellulose derivative film, a cellulose derivative film having a surface energy of 55 to 75 mN / m can be obtained. By using this cellulose derivative film as a transparent protective film for a polarizing plate, the adhesion between the polarizing film and the cellulose derivative film can be improved. When the cellulose derivative film of the present invention is used in an OCB mode liquid crystal display device, the optical compensation sheet of the present invention forms an alignment film on the cellulose derivative film and includes a discotic compound or a rod-shaped liquid crystal compound thereon. An optically anisotropic layer may be provided. The optically anisotropic layer is formed by aligning a discotic compound (or rod-shaped liquid crystal compound) on the alignment film and fixing the alignment state. Thus, when providing an optically anisotropic layer on a cellulose derivative film, conventionally, in order to ensure adhesion between the cellulose derivative film and the alignment film, it was necessary to provide a gelatin undercoat layer between the two. By using the cellulose derivative film of the present invention having a surface energy of 55 to 75 mN / m, the gelatin undercoat layer can be dispensed with.

[Use of cellulose derivative film]
[Optical compensation sheet]
The cellulose derivative film of the present invention is preferably used as an optical compensation sheet.

〔Polarizer〕
The cellulose derivative film of the present invention can be used as one member of a polarizing plate. A polarizing plate consists of a polarizing film and two transparent protective films arrange | positioned at the both sides. As one protective film, the above cellulose derivative film can be used. The other protective film may be a normal cellulose acetate film.
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.
The slow axis of the cellulose derivative film of the present invention and the transmission axis of the polarizing film are preferably arranged so as to be substantially parallel.

(Antireflection layer)
It is preferable to provide an antireflection layer on the transparent protective film disposed on the opposite side of the polarizing plate from the liquid crystal cell. Particularly in the present invention, (1) an antireflection layer in which at least a light scattering layer and a low refractive index layer are laminated in this order on a transparent protective film, or (2) a medium refractive index layer and a high refractive index on the transparent protective film. An antireflection layer in which a layer and a low refractive index layer are laminated in this order is preferably used. Hereinafter, preferred examples thereof will be described in order.

(1) Antireflection layer in which a light scattering layer and a low refractive index layer are provided on a transparent protective film In the light scattering layer in the present invention, mat particles are dispersed, and the material of portions other than the mat particles in the light scattering layer Is preferably in the range of 1.50 to 2.00, and the refractive index of the low refractive index layer is preferably in the range of 1.35 to 1.49. In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, 2 to 4 layers.

The antireflection layer has an uneven surface shape with a center line average roughness Ra of 0.08 to 0.40 μm, a 10-point average roughness Rz of 10 times or less of Ra, an average mountain valley distance Sm of 1 to 100 μm, and an uneven depth. Designed so that the standard deviation of the height of the convex part from the part is 0.5 μm or less, the standard deviation of the average mountain valley distance Sm with respect to the center line is 20 μm or less, and the surface with the inclination angle of 0 to 5 degrees is 10% or more. By doing so, sufficient anti-glare properties and a visually uniform matte feeling are achieved, which is preferable. Further, the ratio of the minimum value and the maximum value of the reflectance within the range of a ^* value −2 to 2, b ^* value −3 to 3, and 380 nm to 780 nm under the light source C is 0.5. By being -0.99, the color of reflected light becomes neutral, which is preferable. Further, by b ^* value of transmitted light under C light source is 0 to 3, the white display yellowness when applied is reduced in the display device, preferably. In addition, when a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection film of the present invention and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less, so that a high-definition panel can be obtained. Glare when applying the film of the present invention is reduced, which is preferable.

  The optical properties of the antireflection layer are as follows: specular reflectance of 2.5% or less, transmittance of 90% or more, and 60 ° gloss of 70% or less, thereby suppressing reflection of external light and improving visibility. Therefore, it is preferable. In particular, the specular reflectance is more preferably 1% or less, and further preferably 0.5% or less. Haze 20% to 50%, internal haze / total haze value 0.3 to 1, haze value after formation of low refractive index layer from haze value to light scattering layer within 15%, comb width at 0.5 mm Transmission image clarity 20% to 50%, vertical transmission light / transmittance ratio of 2 degrees from vertical to 1.5 to 5.0 prevents glare on high-definition LCD panels, characters, etc. Reduction of blur is achieved, which is preferable.

（式中、ｍは正の奇数であり、ｎ1は低屈折率層の屈折率であり、そして、ｄ1は低屈折率層の膜厚（ｎｍ）である。また、λは波長であり、５００〜５５０ｎｍの範囲の値である。） <Low refractive index layer>
The refractive index of the low refractive index layer of the antireflection film is 1.20 to 1.49, preferably 1.30 to 1.44. Furthermore, the low refractive index layer preferably satisfies the following mathematical formula (9) from the viewpoint of reducing the reflectance.

(Where m is a positive odd number, n1 is the refractive index of the low refractive index layer, and d1 is the film thickness (nm) of the low refractive index layer. Also, λ is the wavelength, 500 It is a value in the range of ˜550 nm.)

  The low refractive index layer contains a fluorine-containing polymer as a low refractive index binder. The fluorine polymer is preferably a fluorine-containing polymer that is crosslinked by heat or ionizing radiation having a coefficient of dynamic friction of 0.03 to 0.20, a contact angle with water of 90 to 120 °, and a sliding angle of pure water of 70 ° or less. When the antireflection film of the present invention is mounted on an image display device, the lower the peel strength from a commercially available adhesive tape, the easier it is to peel off after sticking a seal or memo, preferably 500 gf or less, more preferably 300 gf or less, More preferably, it is 100 gf or less. Further, the higher the surface hardness measured with a micro hardness tester, the harder it is to scratch, preferably 0.3 GPa or more, more preferably 0.5 GPa or more.

  Examples of the fluorine-containing polymer used in the low refractive index layer include hydrolysis and dehydration condensate of perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane). And a fluorine-containing copolymer having a fluorine-containing monomer unit and a structural unit for imparting crosslinking reactivity as structural components.

  Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole. Etc.), part of (meth) acrylic acid or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (trade name, manufactured by Osaka Organic Chemical Co., Ltd.) and M-2020 (made by Daikin, trade name)), complete or partially fluorinated Although vinyl ethers etc. are mentioned, Perfluoroolefins are preferable, and hexafluoropropylene is particularly preferable from the viewpoint of refractive index, solubility, transparency, availability, and the like.

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in advance in the molecule such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino groups , Obtained by polymerization of a monomer having a sulfo group or the like (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) And a structural unit obtained by introducing a crosslinking reactive group such as a (meth) acryloyl group into these structural units by a polymer reaction (for example, it can be introduced by a technique such as allowing acrylic acid chloride to act on a hydroxy group) And the like.

  In addition to the above-mentioned fluorine-containing monomer units and structural units for imparting crosslinking reactivity, monomers not containing fluorine atoms can be copolymerized as appropriate from the viewpoints of solubility in solvents and film transparency. There are no particular limitations on the monomer units that can be used in combination. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2) -Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl) Vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butylacrylamide, N- Black hexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

  As described in JP-A-10-25388 and JP-A-10-147739, a curing agent may be appropriately used in combination with the above polymer.

<Light scattering layer>
The light scattering layer is formed for the purpose of contributing to the film light diffusibility due to surface scattering and / or internal scattering and hard coat properties for improving the scratch resistance of the film. Therefore, it is formed including a binder for imparting hard coat properties, matte particles for imparting light diffusibility, and inorganic fillers for increasing the refractive index, preventing crosslinking shrinkage, and increasing the strength as necessary. The

  The thickness of the light scattering layer is preferably 1 to 10 μm and more preferably 1.2 to 6 μm for the purpose of imparting hard coat properties. If it is too thin, the hard property will be insufficient, and if it is too thick, curling and brittleness will deteriorate and the workability will be insufficient.

  The binder of the scattering layer is preferably a polymer having a saturated hydrocarbon chain or a polyether chain as the main chain, and more preferably a polymer having a saturated hydrocarbon chain as the main chain. The binder polymer preferably has a crosslinked structure. As the binder polymer having a saturated hydrocarbon chain as a main chain, a polymer of an ethylenically unsaturated monomer is preferable. As the binder polymer having a saturated hydrocarbon chain as the main chain and having a crosslinked structure, a (co) polymer of monomers having two or more ethylenically unsaturated groups is preferable. In order to make the binder polymer have a high refractive index, the monomer structure contains an aromatic ring, at least one atom selected from halogen atoms other than fluorine, sulfur atoms, phosphorus atoms, and nitrogen atoms. You can also choose.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di ( (Meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (Meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3- Chlorohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), modified ethylene oxide, vinylbenzene and derivatives thereof (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1, 4-divinylcyclohexanone), vinyl sulfone (eg divinyl sulfone), acrylamide (eg methylene bisacrylamide) and methacrylamide. Two or more of these monomers may be used in combination.

  Specific examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. Two or more of these monomers may be used in combination.

Polymerization of the monomer having an ethylenically unsaturated group can be carried out by irradiation with ionizing radiation or heating in the presence of a photo radical initiator or a thermal radical initiator.
Accordingly, a coating liquid containing a monomer having an ethylenically unsaturated group, a photo radical initiator or a thermal radical initiator, mat particles and an inorganic filler is prepared, and the coating liquid is applied on a transparent support and then ionizing radiation or heat is applied. The antireflection film can be formed by curing by the polymerization reaction. As these photo radical initiators, known ones can be used.

The polymer having a polyether as the main chain is preferably a ring-opening polymer of a polyfunctional epoxy compound. The ring-opening polymerization of the polyfunctional epoxy compound can be performed by irradiation with ionizing radiation or heating in the presence of a photoacid generator or a thermal acid generator.
Therefore, a coating liquid containing a polyfunctional epoxy compound, a photoacid generator or a thermal acid generator, matte particles and an inorganic filler is prepared, and the coating liquid is applied onto a transparent support and then subjected to a polymerization reaction by ionizing radiation or heat. Curing can form an antireflection film.

Instead of or in addition to a monomer having two or more ethylenically unsaturated groups, a monomer having a crosslinkable functional group is used to introduce a crosslinkable functional group into the polymer, and by reaction of this crosslinkable functional group, A crosslinked structure may be introduced into the binder polymer.
Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition.
These binder polymers having a crosslinkable functional group can form a crosslinked structure by heating after coating.

For the purpose of imparting antiglare properties, the light scattering layer contains matte particles having an average particle size of 1 to 10 μm, preferably 1.5 to 7.0 μm, such as inorganic compound particles or resin particles, than filler particles. Is done.
As specific examples of the mat particles, inorganic particles such as silica particles and TiO ₂ particles; resin particles such as acrylic particles, cross-linked acrylic particles, polystyrene particles, cross-linked styrene particles, melamine resin particles, and benzoguanamine resin particles are preferable. Can be mentioned. Of these, crosslinked styrene particles, crosslinked acrylic particles, crosslinked acrylic styrene particles, and silica particles are preferable.
The shape of the mat particles can be either spherical or irregular.

  Further, two or more kinds of mat particles having different particle sizes may be used in combination. It is possible to impart anti-glare properties with mat particles having a larger particle size and to impart other optical characteristics with mat particles having a smaller particle size.

  Further, the particle size distribution of the mat particles is more preferably monodispersed, and the particle sizes of the particles are preferably closer to each other. For example, when a particle having a particle size of 20% or more than the average particle size is defined as a coarse particle, the ratio of the coarse particle is preferably 1% or less, more preferably 0.1% of the total number of particles. Or less, more preferably 0.01% or less. The matting particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and a matting agent having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree thereof.

The mat particles are contained in the light scattering layer so that the amount of mat particles in the formed light scattering layer is preferably 10 to 1000 mg / m ² , more preferably 100 to 700 mg / m ² .
The particle size distribution of the mat particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution.

The light scattering layer is made of an oxide of at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, in addition to the matte particles, in order to increase the refractive index of the layer. Thus, it is preferable that an inorganic filler having an average particle size of 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less is contained.
Conversely, in order to increase the refractive index difference from the mat particles, it is also preferable to use a silicon oxide in order to keep the refractive index of the layer low in the light scattering layer using the high refractive index mat particles. The preferred particle size is the same as that of the inorganic filler described above.
Specific examples of the inorganic filler to be used in the light scattering _{layer, TiO 2, ZrO 2, Al} 2 O 3, In 2 O 3, ZnO, SnO 2, Sb 2 O 3, ITO and SiO ₂ and the like. TiO ₂ and ZrO ₂ are particularly preferable in terms of increasing the refractive index. The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.
The amount of these inorganic fillers added is preferably 10 to 90% of the total mass of the light scattering layer, more preferably 20 to 80%, and particularly preferably 30 to 75%.
Such a filler does not scatter because the particle size is sufficiently smaller than the wavelength of light, and a dispersion in which the filler is dispersed in a binder polymer behaves as an optically uniform substance.

  The bulk refractive index of the mixture of binder and inorganic filler in the light scattering layer is preferably 1.48 to 2.00, more preferably 1.50 to 1.80. In order to make the refractive index within the above range, the kind and amount ratio of the binder and the inorganic filler may be appropriately selected. How to select can be easily known experimentally in advance.

  In order to ensure surface uniformity such as coating unevenness, drying unevenness, point defects, etc., the light scattering layer should be coated with either a fluorine-based surfactant or a silicone-based surfactant, or both for forming an antiglare layer. Contained in the composition. In particular, a fluorine-based surfactant is preferably used because an effect of improving surface defects such as coating unevenness, drying unevenness, and point defects of the antireflection film of the present invention appears in a smaller addition amount. The purpose is to increase productivity by giving high-speed coating suitability while improving surface uniformity.

(2) Antireflective layer in which a medium refractive index layer, a high refractive index layer, and a low refractive index layer are laminated in this order on a transparent protective film At least a medium refractive index layer, a high refractive index layer, and a low refractive index layer ( The antireflection film having the layer structure in the order of the outermost layer 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 Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. Also good. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or higher, more preferably 2H or higher, even more preferably 3H or higher, in a pencil hardness test according to JIS K5400.

<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 inorganic compound ultrafine particle having a high refractive index having an average particle size 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 obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No. 1, anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, a core-shell structure with high refractive index particles as a core (Japanese Patent Laid-Open No. 2001-166104, etc.), a specific Examples include a combination of dispersants (for example, JP-A No. 11-153703, US Pat. No. 6,210,858, JP-A No. 2002-27776069, etc.).
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Furthermore, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 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 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 formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine 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 fluorine atoms in the range of 35 to 80% by mass.
For example, paragraphs [0018] to [0026] of JP-A-9-222503, paragraphs [0019] to [0030] of JP-A-11-38202, paragraphs [0027] to [0028] of JP-A-2001-40284, And compounds described in JP 2000-284102 A.
The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (trade name, manufactured by Chisso Corporation), 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 the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.

Also preferred is 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.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
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 still more preferably 60 to 120 nm.

(3) Other layers of antireflection layer Further, a hard coat layer, a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, a protective layer and the like may be provided.

<Hard coat layer>
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the transparent protective film provided with the antireflection layer. In particular, it is preferably provided between the transparent support 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 hydrous 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 composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

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 (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
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 strength of the hard coat layer is preferably H or more, more preferably 2H or more, and even more preferably 3H or more in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

<Antistatic layer>
In the case of providing an antistatic layer, it is preferable to impart conductivity with a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. The use of hygroscopic substances, water-soluble inorganic salts, certain surfactants, cationic polymers, anionic polymers, colloidal silica, etc. can give a volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ). There is a problem that dependency is large, and sufficient conductivity cannot be secured at low humidity. Therefore, a metal oxide is preferable as the conductive layer material. Some metal oxides are colored, but using these metal oxides as the conductive layer material is not preferable because the entire film is colored. Zn, Ti, Al, In, Si, Mg, Ba, Mo, W, or V can be cited as the metal forming the metal oxide without coloring, and it is preferable to use a metal oxide containing these as main components. . Specific examples include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O ₅ , or a composite oxide thereof. In particular, ZnO, TiO ₂ and SnO ₂ are preferable. Examples of containing different atoms include, for example, additives such as Al and In for ZnO, addition of Sb, Nb and halogen elements for SnO ₂ , and Nb and Ta for TiO ₂ . Addition is effective. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a material in which the above metal oxide is adhered to other crystalline metal particles or fibrous materials (for example, titanium oxide) may be used. The volume resistance value and the surface resistance value are different physical properties and cannot be simply compared. However, in order to secure a conductivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less in volume resistance, It is sufficient that the layer has a surface resistance value of approximately 10 ⁻¹⁰ (Ω / □) or less, and more preferably 10 ⁻⁸ (Ω / □). The surface resistance value of the conductive layer needs to be measured as a value when the antistatic layer is the outermost layer, and can be measured in the middle of forming the laminated film described in this specification.

[Liquid Crystal Display]
The polarizing plate using the cellulose derivative film of the present invention is useful for a liquid crystal display device. The polarizing plate of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid Crystal), OCB (Optically Compensatory Bend), STN (Supper Twisted Nematic), VA (Vertically Aligned) and Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. Among these, it can be preferably used for the OCB mode or the VA mode.

  The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is converted into a multi-domain (MVA mode) for widening the viewing angle ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).
In the OCB mode and VA mode liquid crystal display devices, the liquid crystal cell and two polarizing plates may be arranged on both sides thereof. In the VA mode, the polarizing plate may be arranged on the backlight side of the cell. The liquid crystal cell carries a liquid crystal between two electrode substrates.

EXAMPLES The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the specific examples shown below.
The raw materials used in the examples and comparative examples were all commercially available and used as they were.

<Synthesis Example 1: Synthesis of methylcellulose benzoate (P-1)>
In a 3 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, 30 g of methylcellulose (methoxy substitution degree 1.8) and 600 mL of pyridine were weighed and stirred at room temperature. To this, 234 mL of benzoyl chloride was slowly added dropwise and stirred at 60 ° C. for 6 hours. After the reaction, the reaction solution was returned to room temperature and quenched by adding 200 mL of methanol under ice cooling. When the reaction solution was added to 6 L of methanol with vigorous stirring, a white solid was precipitated. The white solid was filtered off by suction filtration and washed with a large amount of methanol three times. The obtained white solid was vacuum-dried at 100 ° C. for 6 hours to obtain the objective cellulose derivative (P-1) as a white powder (44.7 g).

<Synthesis Example 2: Synthesis of ethyl cellulose benzoate (P-2)>
In a 3 L three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, 50 g of ethylcellulose (ethoxy substitution degree 2.6) and 500 mL of pyridine were weighed and stirred at room temperature. Benzoyl chloride 42mL was slowly dripped here, and it stirred at 60 degreeC for 6 hours. After the reaction, the reaction solution was returned to room temperature and quenched by adding 100 mL of methanol under ice cooling. When the reaction solution was poured into methanol / water (6 L / 2 L) with vigorous stirring, a white solid was precipitated. The white solid was filtered off by suction filtration and washed with a large amount of methanol / water (3/1) mixed solvent three times. The obtained white solid was vacuum-dried at 100 ° C. for 6 hours to obtain the target cellulose derivative (P-2) as a white powder (36.3 g).

<Synthesis Example 3: Synthesis of ethyl cellulose phenylbenzoate (P-3)>
The target cellulose derivative (P-3) was obtained as a white powder (47.0 g) in the same manner except that benzoyl chloride was changed to 4-phenylbenzoyl chloride in Synthesis Example 2.

<Synthesis Example 4: Synthesis of ethyl cellulose asalonate (P-4)>
The target cellulose derivative (P-4) was obtained as a white powder in the same manner as in Synthesis Example 2 except that benzoyl chloride was changed to asalonyl chloride (2,4,5-trimethoxybenzoyl chloride) (31. 0g).

<Synthesis Example 5: Synthesis of ethyl cellulose methyl benzoate (P-5)>
The target cellulose derivative (P-5) was obtained as a white powder (46.8 g) in the same manner except that benzoyl chloride was changed to 4-methylbenzoyl chloride in Synthesis Example 2.

<Synthesis Example 6: Synthesis of ethyl cellulose naphthoate (P-6)>
The target cellulose derivative (P-6) was obtained as a white powder (24.5 g) in the same manner except that benzoyl chloride was changed to 2-naphthoyl chloride in Synthesis Example 2.

<Synthesis Example 7: Synthesis of methylcellulose benzoate (P-7)>
The target cellulose derivative (P-7) is obtained in the same manner except that the amount of benzoyl chloride is changed to 40 mL in Synthesis Example 1.

<Synthesis Example 8: Synthesis of ethyl cellulose benzoate (P-8)>
The objective cellulose derivative (P-8) was obtained as a white powder (35.0 g) in the same manner except that the amount of benzoyl chloride was changed to 8 mL in Synthesis Example 2.

<Synthesis Example 9: Synthesis of hydroxypropylcellulose benzoate (H-1)>
According to the method described in JP-A-2005-283997, hydroxypropylcellulose benzoate (H-1), which is a comparative compound, can be synthesized by changing the acylating agent from acetic anhydride to benzoyl chloride and adjusting the amount of the acylating agent as appropriate. .

<Synthesis Example 10: Synthesis of hydroxypropyl cellulose acetate (H-2)>
According to the method described in JP-A-2005-283997, hydroxypropyl cellulose acetate (H-2) as a comparative compound can be synthesized.

<Example 1: Preparation of cellulose derivative film and measurement of film properties>
[Film production]
10 g of the cellulose derivative (P-1) obtained above was dissolved in 117 mL of methylene chloride, and this was filtered under pressure. The obtained dope was cast on an A3 large hydrophobic glass plate using an applicator (clearance 1.00). This was leveled for 1 minute in a 25 ° C. closed system and subsequently dried in a blow dryer at 45 ° C. for 8 minutes. The film was peeled off from the glass plate and sandwiched between stainless steel frames, which were then dried in a dryer at 100 ° C. for 10 minutes and in a dryer at 140 ° C. for 30 minutes to obtain a transparent film F-1.
Instead of cellulose derivative P-1, cellulose derivatives P-2 to 8, cellulose acetate (CTA, acetyl substitution degree 2.9), methyl cellulose (MC, methoxy substitution degree 1.6) ethyl cellulose (EC, ethoxy substitution degree 2. 6) and H-1 to 2, respectively, were formed in the same manner to produce transparent films F-2 to 8 which are examples of the present invention and films F-11 to F-15 which are comparative examples, respectively. did. In addition, transparent films F-9 and F-10 were obtained in the same manner except that the clearance of the applicator was changed to 0.6 and 0.4 using the cellulose derivative P-2.

[Film physical property measurement]
The brittleness and surface state of the film were evaluated functionally as follows.
(Brittleness) ○: Not cracked during peeling, drying, and transporting ×: Partially cracking during stripping, drying, and transporting (Surface shape) ○: Transparent and uniform state ×: State of white turbidity Also, Rth of the film is 589 nm Is the value of

From the results in Table 1, it can be understood that the films produced using the cellulose derivatives P-1 to P-8 of the present invention exhibit a large Rth.
On the other hand, the film F-11 (Comparative Example 1) produced using cellulose acetate substituted only with an acyl group had a small Rth of about 10 nm. Films F-12 and F-13 (Comparative Examples 2 and 3) prepared using methyl cellulose or ethyl cellulose substituted only with a methyl group or an ethyl group are white turbid during film formation, and are obtained as a transparent film. It was more brittle. As a result, optical property evaluation was not achieved.
Moreover, even if it has both an ester group and an ether group, the total of the substitution degree is low, and the cellulose derivative that does not satisfy the formula (I) could not be formed (Comparative Example 4, F-14). .
Furthermore, even if it has both an ester group and an ether group, a cellulose derivative in which the aliphatic hydrocarbon group part of the ether group is not unsubstituted and is substituted with a substituent containing a highly polar atom such as an oxygen atom. In the film F-15 produced using the same, Rth was as low as F-12 (Comparative Example 5).
From the above results, it can be understood that by combining both ether and ester substituents, an effect not obtained with conventional cellulose derivatives, that is, film forming properties and novel optical properties can be obtained. Further, since the film of the present invention expresses a large Rth, it has a suitable Rth even if it is thinned, and is considered preferable as an optical film material.

<Example 2: Production and evaluation of polarizing plate>
The produced film F-2 and a cellulose acylate film (Fuji Film Co., Ltd., Fuji TAC) were immersed in an aqueous 1.5N sodium hydroxide solution at 60 ° C. for 2 minutes. Thereafter, it was immersed in a 0.1N aqueous sulfuric acid solution for 30 seconds, and then passed through a water washing bath to obtain saponified F-2 and Fuji TAC.

  According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a peripheral speed difference is given between two pairs of nip rolls, and a 75 μm-thick polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., 9 × 75RS) is stretched in the longitudinal direction. A polarizing film was obtained.

  The polarizing film thus obtained and the saponified F-2 were mixed with a 3% by weight aqueous solution of polyvinyl alcohol (PVA) (manufactured by Kuraray Co., PVA-117H) as an adhesive, and the longitudinal direction of the film was 45 °. In this way, the polarizing plate Pol-1 was prepared by laminating with a layer configuration of “saponified F-1 / polarizing film / saponified FujiTAC”.

<Example 3: Production and evaluation of liquid crystal display device>
Of two pairs of polarizing plates installed with a liquid crystal layer sandwiched between 26-inch and 40-inch liquid crystal display devices (manufactured by Sharp Corporation) using VA type liquid crystal cells, a polarizing plate on one side on the viewer side is used. It peeled off and the said polarizing plate Pol-1 was affixed instead using the adhesive. A liquid crystal display device was manufactured by arranging the transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side to be orthogonal to each other. Color unevenness of the obtained liquid crystal display device was observed. The liquid crystal display device incorporating the polarizing plate Pol-1 of the present invention was excellent without color unevenness.

Claims (11)

A film comprising a cellulose derivative containing a polymerization unit represented by the following general formula (1) and satisfying the following mathematical formulas (I) to (III):

[Wherein, R ² , R ³ and R ⁶ each independently represents a hydrogen atom, an unsubstituted aliphatic hydrocarbon group or an acyl group. ]
(I) 0 ≦ DS _A ≦ 1.4
(II) 0 <DS _B
(III) 0 <DS _C
[Wherein DS _A is the number of hydrogen atoms present as R ² , R ³ and R ⁶ in the unit, and DS _B is present as R ² , R ³ and R ^{6 in} the same unit, respectively. Is the number of unsubstituted aliphatic hydrocarbon groups, and DS _C is the number of acyl groups present as R ² , R ³ and R ^{6 in} the same unit, respectively, and DS _A + DS _B + DS _C is 3 is there. ] The film according to claim 1, wherein the cellulose derivative satisfies the following formula (IV).
(IV) DS _C ≦ DS _B The film according to claim 1, wherein the cellulose derivative satisfies the following formulas (I) ′ to (III) ′.
(I) ′ 0 ≦ DS _A ≦ 0.4
(II) ′ 1.5 ≦ DS _B ≦ 2.7
(III) ′ 0.1 ≦ DS _C ≦ 1.5 The acyl group which the said cellulose derivative has is an aromatic acyl group, The film of any one of Claims 1-3 characterized by the above-mentioned. An optical compensation sheet comprising the film according to any one of claims 1 to 4 or having the film according to any one of claims 1 to 4. A polarizing plate comprising a polarizer and the film according to claim 1. A liquid crystal display device comprising the film according to claim 1. A cellulose derivative comprising a polymer unit represented by the following general formula (1) and satisfying the following mathematical formulas (I) to (III):

[Wherein, R ² , R ³ and R ⁶ each independently represents a hydrogen atom, an unsubstituted aliphatic hydrocarbon group or an acyl group. ]
(I) 0 ≦ DS _A ≦ 1.4
(II) 0 <DS _B
(III) 0 <DS _C
[Wherein DS _A is the number of hydrogen atoms present as R ² , R ³ and R ⁶ in the unit, and DS _B is present as R ² , R ³ and R ^{6 in} the same unit, respectively. Is the number of unsubstituted aliphatic hydrocarbon groups, and DS _C is the number of acyl groups present as R ² , R ³ and R ^{6 in} the same unit, respectively, and DS _A + DS _B + DS _C is 3 is there. ] The cellulose derivative according to claim 8, which satisfies the following formula (IV).
(IV) DS _C ≦ DS _B The cellulose derivative according to claim 8 or 9, wherein the following formulas (I) 'to (III)' are satisfied.
(I) ′ 0 ≦ DS _A ≦ 0.4
(II) ′ 1.5 ≦ DS _B ≦ 2.7
(III) ′ 0.1 ≦ DS _C ≦ 1.5 The cellulose derivative according to any one of claims 8 to 10, wherein the acyl group is an aromatic acyl group.