JP2008095027A - Cellulose film, optical compensating film, polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose film which can freely control a retardation (Re) value in the inplane direction and a retardation (Rth) value in the thickness direction and is excellent in the moisture dependency of retardation, and to provide an optical compensating sheet, a polarizing plate, and a liquid crystal display device using the same. <P>SOLUTION: This cellulose film comprises a cellulose compound represented by general formula (I). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose film, an optical compensation sheet, a polarizing plate and a liquid crystal display device. More specifically, the values of in-plane retardation (Re) and thickness direction retardation (Rth) are freely controlled in a wide range. In addition, the present invention relates to a cellulose film excellent in humidity dependency of retardation, an optical compensation sheet using the cellulose film, a polarizing plate, and a liquid crystal display device.

Cellulose acylate films are widely used as polarizing plate protective films for liquid crystal display devices due to their transparency, toughness and optical isotropy.
In recent years, with the widespread use of liquid crystal display devices, demands for display performance and durability have increased, and response speeds have been improved, and a wider viewing angle such as contrast and color balance when viewed from an oblique direction with respect to the display image. It has become a problem to compensate with. In order to solve these problems, VA (Vertical Alignment), OCB (Optical Compensated Bend), or IPS (In-Plane Switching) display devices have been developed. There is a demand for an optical film material having a foundation development property. In particular, the retardation film is required to control the in-plane retardation (Re) and the thickness direction retardation (Rth) according to each of various liquid crystal systems.

In response to such demands, cellulose acetate, which has been widely used as an optical film material, has a feature that it is difficult to increase the stretch ratio. Since this is a high polymer, there is a problem that the retardation value easily changes due to fluctuations in humidity.
As means for solving these problems, an optical film that uses a mixed acylate of fatty acid cellulose ester cellulose such as cellulose acetate propionate or cellulose acetate butyrate has been proposed (for example, see Patent Documents 1 and 2). .
These fatty acid celluloses are excellent materials having a possibility of expanding the retardation expression of cellulose acetate. However, the value of Re that can be controlled by the above optical film is, for example, 30 nm or less for cellulose acetate propionate and the value of Rth is limited to the range of 60 to 300 nm, and sufficient retardation is developed according to diversified liquid crystal systems. It has not reached.

An optical film using a cellulose acylate composed of an ester with an aromatic carboxylic acid as a cellulose having an aromatic group has also been proposed (see, for example, Patent Document 3). However, in reality, sufficient knowledge about optical properties such as retardation has not been obtained, and in particular, the substitution position and degree of substitution of aromatic acyl groups have not been studied.
2,3-Di-O-acetyl-6-O-benzoyl-cellulose and 6-O-acetyl-2,3-di-O-benzoyl-cellulose as cellulose acylates considering the substitution position of aromatic substituents The synthesis of has been reported. However, its use is an optical resolution column, and the optical properties of the film have not been studied (for example, see Non-Patent Document 1).

JP 2001-188128 A JP 2005-352620 A JP 2002-179701 A “Chirality”, (2000), 12 (9), 670-674.

  INDUSTRIAL APPLICABILITY The present invention is a cellulose film that can freely control the values of in-plane retardation (Re) and thickness direction retardation (Rth) in a wide range and has excellent humidity dependency of retardation, and optical compensation using the same. It aims at providing a sheet | seat, a polarizing plate, and a liquid crystal display device.

The above object of the present invention has been achieved by the following means.
[Aspect 1]
The cellulose film containing the cellulose compound characterized by being represented by the following general formula (I).

[Wherein, R ¹⁶ , R ¹³ and R ¹² each independently represents a group containing a hydrogen atom, an aliphatic group or an aromatic group. -X ^16- , -X ¹³ -and -X ¹² -are each independently * ¹ -O-, * ¹ -OOC- and * ¹ -OOCNH- (* ¹ is a bond on the six-membered ring side of the cellulose skeleton) Represents). n ¹ represents the average degree of polymerization, represents an integer of 10 to 1500. In addition, R ¹⁶ , R ¹³ , R ¹² , —X ¹⁶ —, —X ¹³ —, and —X ¹² — present in n ¹ each in the cellulose compound may be the same or different for each structural unit. Furthermore, the following relational expressions (Formula I) and (Formula II) are satisfied.
(Formula I)
DS ¹⁶ _long ≧ DS ¹³ _long + DS ¹² _long
(Formula II)
2.5 ≧ DS ¹² _long + DS ¹³ _long + DS ¹⁶ _long > 0.01
Here, DS ¹⁶ _long , DS ¹³ _long and DS ¹² _long are respectively replaced with -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ^{12 in} the 6th, 3rd and 2nd positions. This represents the degree of substitution at the 6-position, 3-position and 2-position of the substituent having the longest absorption among the 3n ¹ substituents. The substituent having the absorption at the longest wave here is -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ¹² are CH ₃ -X ¹⁶ -R ¹⁶ , CH ₃ -X ^13. In the case of —R ¹³ and CH ₃ —X ¹² —R ¹² , the maximum absorption wavelength at 270 to 450 nm in the solution is the longest wave, and the molar extinction coefficient thereof is 2000 to 1000000. ]
[Aspect 2]
The cellulose film according to aspect 1, wherein the substituent having the longest absorption among the 3n ¹ substituents is a group containing an aromatic group.
[Aspect 3]
The cellulose film according to aspect 1 or 2, wherein the substituent having the longest wave absorption among 3n ¹ substituents is a group containing at least two aromatic rings.
[Aspect 4]
-X ¹⁶ -, - X ¹³ - and -X ¹² - cellulose film according to any one of embodiments 1-3, wherein at least one of which is * ¹ -OOC-.
[Aspect 5]
The cellulose according to any one of aspects 1 to 4, wherein at least one of the 3n ¹ groups represented by R ¹⁶ , R ¹³ and R ¹² is a group not containing an aromatic group. the film.
[Aspect 6]
-X ¹⁶ -R ^16, embodiment 1 that at least one of the 3n substituents represented by -X ¹³ -R ¹³ and -X ¹² -R ^12, characterized in that the acetyl, propionyl or butyryl The cellulose film of any one of -5.
[Aspect 7]
A cellulose film obtained by stretching the cellulose film according to any one of aspects 1 to 6 by 0.1% to 500% in at least one direction.
[Aspect 8]
Any one of Embodiments 1 to 7, wherein the in-plane retardation (Re) satisfies the following formula (5) and the retardation in the thickness direction (Rth) satisfies the following formula (6): The cellulose film according to item.
Formula (i): 0 nm ≦ Re ≦ 700 nm
Formula (ii): 0 nm ≦ Rth ≦ 2000 nm
[Aspect 9]
A retardation film using the cellulose film according to any one of aspects 1 to 8.
[Aspect 10]
It is a polarizing plate which consists of a polarizing film and two protective films which pinch | interpose this polarizing film, Comprising: At least one of two protective films is a cellulose film of any one of aspect 1-8, or aspect 9 A polarizing plate, which is the retardation film described in 1.
[Aspect 11]
An optical compensation film comprising an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose film according to any one of aspects 1 to 8 or the retardation film according to aspect 9.
[Aspect 12]
An antireflection film comprising an antireflection layer on the cellulose film according to any one of aspects 1 to 8 or the retardation film according to aspect 9.
[Aspect 13]
It consists of the cellulose film of any one of aspect 1-8, the phase difference film of aspect 9, the polarizing plate of aspect 10, the optical compensation film of aspect 11, and the antireflection film of aspect 12. An image display device using at least one selected from a group.

  The cellulose film containing a cellulose compound used in the film of the present invention can freely control the in-plane direction retardation (Re) and the thickness direction retardation (Rth) in a wide range, and the humidity dependence of the retardation. A cellulose film excellent in properties, an optical compensation sheet, a polarizing plate and a liquid crystal display device using the cellulose film can be produced.

  The present invention is described in detail below.

[Cellulose compound]
In the present invention, the cellulose compound refers to a compound having a cellulose skeleton obtained by introducing a functional group biochemically or chemically using cellulose as a raw material.

  The cellulose compound contained in the cellulose film of the present invention is represented by the following general formula (I).

[Wherein, R ¹⁶ , R ¹³ and R ¹² each independently represents a group containing a hydrogen atom, an aliphatic group or an aromatic group. -X ^16- , -X ¹³ -and -X ¹² -are each independently * ¹ -O-, * ¹ -OOC- and * ¹ -OOCNH- (* ¹ is a bond on the six-membered ring side of the cellulose skeleton) Represents). n ¹ represents the average degree of polymerization, represents an integer of 10 to 1500. In addition, R ¹⁶ , R ¹³ , R ¹² , —X ¹⁶ —, —X ¹³ —, and —X ¹² — present in n ¹ each in the cellulose compound may be the same or different for each structural unit. Furthermore, the following relational expressions (Formula I) and (Formula II) are satisfied.
(Formula I)
DS ¹⁶ _long ≧ DS ¹³ _long + DS ¹² _long
(Formula II)
2.5 ≧ DS ¹² _long + DS ¹³ _long + DS ¹⁶ _long > 0.01
Here, DS ¹⁶ _long , DS ¹³ _long and DS ¹² _long are respectively replaced with -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ^{12 in} the 6th, 3rd and 2nd positions. This represents the degree of substitution at the 6-position, 3-position and 2-position of the substituent having the longest absorption among the 3n ¹ substituents. The substituent having the absorption at the longest wave here is -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ¹² are CH ₃ -X ¹⁶ -R ¹⁶ , CH ₃ -X ^13. In the case of —R ¹³ and CH ₃ —X ¹² —R ¹² , the maximum absorption wavelength at 270 to 450 nm in the solution is the longest wave, and the molar extinction coefficient thereof is 2000 to 1000000. ]

In addition, about two glucopyranose rings located in the terminal of the cellulose compound used for the film of this invention, it is possible to have a substituent also in the hydroxyl group of 1-position or 4-position, but the kind of the substituent is There is no particular limitation. Preferable examples include a hydrogen atom, an alkyl group (preferably having 1 to 24 carbon atoms, more preferably 1 to 18 carbon atoms, particularly preferably 1 to 12 carbon atoms), and an aliphatic acyl group (preferably having 2 to 24 carbon atoms). More preferably, it has 2-18 carbon atoms, particularly preferably 2-12 carbon atoms, and an aromatic acyl group (preferably 6-30 carbon atoms, more preferably 6-24 carbon atoms, particularly preferably 6-20 carbon atoms). ), and, the general formula (I), a group represented by the ^{-X 16 -R 16, -X 13 -R} 13 or -X ¹² -R ¹² can be exemplified.

R ¹⁶ , R ¹³ and R ¹² will be described.
R ¹⁶ , R ¹³ and R ¹² each independently represents a group containing a hydrogen atom, an aliphatic group or an aromatic group.
When R ¹⁶ , R ¹³ and R ¹² are aliphatic groups, these groups are preferably alkyl groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms). And examples thereof include a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an n-octyl group, an n-decyl group, an n-hexadecyl group, a cyclopropyl group, a cyclopentyl, a cyclohexyl group, and the like. (Preferably having 2 to 20 carbon atoms, more preferably 2 to 12, and particularly preferably 2 to 8, and examples thereof include vinyl group, allyl group, 2-butenyl group, and 3-pentenyl group), alkynyl. A group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms such as propargyl group and 3-pentynyl group. )

These groups may further have a substituent, for example, an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12, particularly preferably 1 to 8, such as a methyl group, An ethyl group, an isopropyl group, a tert-butyl group, an n-octyl group, an n-decyl group, an n-hexadecyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, etc.), an alkenyl group (preferably having 2 carbon atoms). -20, more preferably 2-12, particularly preferably 2-8, for example, vinyl group, allyl group, 2-butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably the number of carbon atoms) 2 to 20, more preferably 2 to 12, particularly preferably 2 to 8, and examples thereof include a propargyl group and a 3-pentynyl group. Group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms such as phenyl group, biphenyl group and naphthyl group), amino group (preferably The number of carbon atoms is 0 to 20, more preferably 0 to 10, particularly preferably 0 to 6, and examples thereof include an amino group, a methylamino group, a dimethylamino group, a diethylamino group, and a dibenzylamino group. A group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12, particularly preferably 1 to 8, such as a methoxy group, an ethoxy group, or a butoxy group), an aryloxy group (preferably carbon The number of atoms is 6 to 20, more preferably 6 to 16, and particularly preferably 6 to 12, for example, phenyloxy group, 2-naphthyloxy group, etc. And an acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as acetyl group, benzoyl group, formyl group, and pivaloyl group). ), An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group), an aryloxycarbonyl group (Preferably 7-20, more preferably 7-16, particularly preferably 7-10, for example, phenyloxycarbonyl group, etc.), acyloxy group (preferably 2-20 carbon atoms, More preferably, it is 2 to 16, particularly preferably 2 to 10, such as acetoxy group, benzoyloxy. And the like. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms such as acetylamino group and benzoylamino group), alkoxycarbonylamino group ( The number of carbon atoms is preferably 2 to 20, more preferably 2 to 16, and particularly preferably 2 to 12, and examples thereof include a methoxycarbonylamino group, and an aryloxycarbonylamino group (preferably 7 to 7 carbon atoms). 20, More preferably, it is 7-16, Most preferably, it is 7-12, for example, a phenyloxycarbonylamino group etc. are mentioned, A sulfonylamino group (Preferably 1-20 carbon atoms, More preferably, it is 1-16. And particularly preferably 1 to 12, for example, methanesulfonylamino group, benzenesulfonate Amino groups, etc.), sulfamoyl groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms such as sulfamoyl group, methylsulfamoyl group, dimethylsulfa). And a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms such as a carbamoyl group and a methylcarbamoyl group). , Diethylcarbamoyl group, phenylcarbamoyl group, etc.), alkylthio group (preferably having 1-20 carbon atoms, more preferably 1-16, particularly preferably 1-12, such as methylthio group, ethylthio group, etc. An arylthio group (preferably having 6 to 20 carbon atoms, More preferably, it is 6-16, Most preferably, it is 6-12, for example, a phenylthio group etc. are mentioned, A sulfonyl group (Preferably 1-20 carbon atoms, More preferably, it is 1-16, Most preferably, it is 1-1. 12, for example, a mesyl group, a tosyl group, etc.), a sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as a methanesulfinyl group, Benzenesulfinyl group, etc.), ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 and particularly preferably 1 to 12, such as ureido group, methylureido group, phenylureido group, etc. A phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12, and examples thereof include diethyl phosphoric acid amide and phenyl phosphoric 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, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group and a 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 30 carbon atoms, especially Preferably it is 3-24, for example, a trimethylsilyl group, a triphenylsilyl group, etc. are mentioned. 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. In addition, R ¹⁶ , R ¹³ , and R ¹² present in n ¹ each in the cellulose compound may be the same or different for each structural unit.

The case where R ¹⁶ , R ¹³ and R ¹² are groups containing an aromatic group will be described.
The definition of aromatics is described in RIKEN Dictionary 5th edition, Iwanami Shoten, pages 1289-1290 (2000). In the present invention, a case R ^16, R ¹³ and R ¹² is a group containing an aromatic group, an aromatic group directly or through a linking ^{group, -X 16 -, - X 13} -, or , —X ¹² — represents a group bonded to the group represented by —X ¹² —.

The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group. As the aromatic hydrocarbon group, those having 6 to 30 carbon atoms are preferable, those having 6 to 24 are more preferable, and those having 6 to 18 are particularly preferable. Specific examples of the aromatic hydrocarbon group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an anthryl group, a terphenyl group, a triphenylenyl group, a pyrenyl group, a naphthacenyl group, and a pentacenyl group. More preferred are phenyl group, 1-naphthyl group, 2-naphthyl group and anthryl group, and particularly preferred are phenyl group, 1-naphthyl group and 2-naphthyl group.
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 heterocyclic group include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxazole, oxadiazole, quinoline, isoquinoline, phthalazine. Preferred examples include naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, benzodithiol and tetrazaindene.
More preferably, the aromatic heterocyclic group includes thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, indole, indazole, thiadiazole, oxazole, oxadiazole, quinoline, isoquinoline, naphthyridine, quinoxaline, quinazoline, cinnoline, Examples include acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and benzodithiol.
Particularly preferably, mention may be made of thiophene, imidazole, pyrazole, pyridine, triazole, indole, thiadiazole, oxazole, oxadiazole, quinoline, isoquinoline, quinoxaline, quinazoline, benzimidazole, benzoxazole, benzothiazole, benzotriazole, benzodithiol, etc. Can do.

These aromatic groups may further have a substituent, and examples thereof include a substituent when R ¹⁶ , R ¹³ and R ¹² described above are aliphatic groups.
In the present invention, a group containing two or more aromatic rings is more preferable. For example, a group having an aromatic group as a substituent of the aromatic group (preferred examples include 4-phenylphenyl group, 4-phenoxy group) Phenyl group, 4- (dimethylphenyl) phenyl group, etc.) and benzo-fused groups (for example, 2-naphthyl group, 1-naphthyl group, etc.).

In the present invention, when R ¹⁶ , R ^13, and R ¹² are groups containing an aromatic group, R ¹⁶ , R ^13, and R ¹² are —X ¹⁶ , wherein the aromatic group is directly or via a linking group. It is bonded to a group represented by —, —X ¹³ —, or —X ¹² —.
When the aromatic group is bonded to the group represented by —X ¹⁶ —, —X ¹³ —, or —X ¹² — via a linking group, the linking group is preferably an alkylene group (preferably carbon 1 to 10, more preferably 1 to 8 carbon atoms, particularly preferably 1 to 6 carbon atoms), alkenylene group (preferably 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, particularly preferably carbon number). 2-6), or an alkynylene group (preferably having 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, and particularly preferably 2 to 6 carbon atoms), —O—, —C═O—, —S—. , -S (= O)-, -S (= O) _2- , -NH- and the like.
An alkylene group having 1 to 6 atoms and an alkenylene group having 2 to 6 atoms are more preferable, and an alkylene group having 1 to 4 atoms and an alkenylene group having 2 to 4 atoms are most preferable.
Preferable examples of the combination of the aromatic group and the linking group include a phenylmethyl group, a naphthylmethyl group, a 2-phenylethyl group, a 2-naphthylethyl group, a biphenylmethyl group, and a biphenylethyl group.
These linking groups may further have a substituent, and the linking groups may be bonded to each other to form a composite substituent or a ring.

-X ^16- , -X ¹³ -and -X ¹² -are each independently * ¹ -O-, * ¹ -OOC-, and * ¹ -OOCNH- (* ¹ is the 6-membered ring side of the cellulose skeleton) Represents a bond). More preferred are * ¹ -O- and * ¹ -OOC-, and particularly preferred is * ¹ -OOC-.
Incidentally, -X ¹⁶ present one by ^one n in the cellulose compound -, - X ¹³ - and -X ¹² - may be different from each be the same for each structural unit.

The general formula (I) is characterized by satisfying the following (formula I) and (formula II).
(Formula I)
DS ¹⁶ _long ≧ DS ¹³ _long + DS ¹² _long
(Formula II)
2.5 ≧ DS ¹² _long + DS ¹³ _long + DS ¹⁶ _long > 0.01
Here, DS ¹⁶ _long , DS ¹³ _long and DS ¹² _long are respectively replaced with -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ^{12 in} the 6th, 3rd and 2nd positions. This represents the degree of substitution at the 6-position, 3-position and 2-position of the substituent having the longest absorption among the 3n ¹ substituents. The substituent having the absorption at the longest wave here refers to CH ₃ —X ¹⁶ —R ¹⁶ , CH ₃ —X with respect to —X ¹⁶ —R ¹⁶ , —X ¹³ —R ¹³ and —X ¹² —R ^12. Substitution in which the absorption maximum wavelength at 270 to 450 nm in the solution is the longest wave and the molar extinction coefficient thereof is 2000 to 1000000 when it is derived into a compound of ¹³ -R ¹³ and CH ₃ -X ¹² -R ¹² Represents a group. The absorption maximum wavelength is a wavelength at which the molar extinction coefficient is greatest at 270 to 450 nm in the solution. In the present invention, when the compound of CH ₃ —X ¹⁶ —R ¹⁶ , CH ₃ —X ¹³ —R ¹³ and CH ₃ —X ¹² —R ¹² exhibits a plurality of absorption peaks, the longest wavelength side This is expressed using the absorption maximum wavelength of the absorption peak. In the present invention, the solution absorption spectrum of the compounds CH ₃ —X ¹⁶ —R ¹⁶ , CH ₃ —X ¹³ —R ¹³ and CH ₃ —X ¹² —R ¹² is preferably measured with a dichloromethane solution. If it was difficult to measure the molar extinction coefficient due to low solubility in dichloromethane, a soluble solvent was selected from any solvent such as chloroform, methanol, acetonitrile, acetone, ethyl methyl ketone, ethyl acetate, and pyridine. The value may be substituted. When dissolving in a plurality of solvents including dichloromethane, a value measured with a dichloromethane solution is used as a reference.

In the present invention, it is preferable that the substituent having the longest absorption includes an aromatic group. Further, the substituent having absorption at the longest wave has an absorption maximum wavelength of preferably 210 to 420 nm, more preferably 230 to 400 nm, and particularly preferably 240 to 390 nm.
When the absorption maximum wavelength is shorter than 210 nm, the retardation may not be sufficiently developed. Further, when the absorption maximum wavelength is longer than 420 nm, the film is likely to be colored, and the performance as an optical film may be deteriorated.
In the present invention, molar absorption at the absorption maximum wavelength of the compounds CH ₃ —X ¹⁶ —R ¹⁶ , CH ₃ —X ¹³ —R ¹³ and CH ₃ —X ¹² —R ¹² derived from the substituent having the longest wave length. The range of the coefficient is 2000 to 1000000. The unit of molar extinction coefficient is [L / (mol · cm)]. Preferably it is 3000-700000, More preferably, it is 5000-500000, Most preferably, it is 7000-100,000. In order to obtain the effect of the present invention, it is preferable that the molar extinction coefficient is large. However, when the maximum molar extinction coefficient in the visible region (wavelength range of 430 to 700 nm) is 2000 or less, the film is hardly colored. A good optical film that cannot be detected can be obtained.

Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. In the present invention, the average degree of substitution refers to a ratio in which any one of the hydroxyl groups at the 2-position, 3-position and 6-position is substituted with the specified substituent. When the hydroxyl groups at the 2nd, 3rd and 6th positions are all substituted with the desired substituents, the average degree of substitution is 3.0.
The cellulose compound used in the film of the present invention preferably has an average degree of substitution of 1.0 to 3.0, more preferably 1.5 to 3.0, and 1.7 to 2.95. It is particularly preferred.

Among the substituents substituted as -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ^{12 at} the 6-position, 3-position and 2-position, the longest wave is absorbed. The total degree of substitution at the 2-position, 3-position and 6-position of the substituent is 0.01 to 2.5 as shown in (Formula II). Preferably it is 0.01-1.5, More preferably, it is 0.02-1.2, 0.05-0.5 is especially preferable. If the total substitution degree of the substituents having the absorption at the longest wave is less than 0.01, the absorption of the substituents is not preferable because the optical properties of the polymer are not substantially affected. On the other hand, when the degree of substitution exceeds 2.5, the optical characteristics of the present invention are hardly exhibited.
Among them, the substitution degree at the 6-position of the substituent having the absorption in the longest wave is preferably 0.01 to 1.0, more preferably 0.02 to 1.0, and particularly preferably 0.05 to 0.5. Further, the total substitution degree of the 2-position and 3-position of the substituent having the absorption at the longest wave is preferably 0.0 to 0.5, more preferably 0.0 to 0.25, and 0.0 to 0.1. Is particularly preferred.

  In the present invention, as shown in (Formula I), for the substituent having the longest absorption, the substitution degree at the 6-position is higher than the total substitution degree at the 2- and 3-positions. It is characterized by being. By distributing the degree of substitution in this way, the effects of the present invention can be effectively expressed.

The average degree of substitution of substituents in the present invention, "Cellulose Communication", 6,73-79 (1999) or "Chirality", 12 (9), according to the method described in 670-674, ¹ H-NMR or It can be determined by ¹³ C-NMR. Thereby, the substitution degree for every substitution position of each substituent can be calculated | required.

In the present invention, preferred examples when the substituents substituted as -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ¹² are the substituents having the longest absorption are benzoyl Oxy, 4-methoxybenzoyloxy, 4-methylbenzoyloxy, 2,4-dimethoxybenzoyloxy, 2,4,5-trimethoxybenzoyloxy, 2,3,4-trimethoxybenzoyloxy, 4-nitrobenzoyloxy, 1-naphthalenecarbonyloxy, 2-naphthalenecarbonyloxy, 4-phenoxybenzoyloxy, 4-phenylbenzoyloxy, 4- (4′-methoxyphenoxy) benzoyloxy, 4- (4′-methoxyphenoxy) phenylbenzoyloxy, 4 -(2,2-dicyanovinyl) benzoyloxy, 4-bromobenzoy Oxy, 4-chlorobenzoyloxy, 2,4,6-tribromobenzoyloxy, phenylacetyloxy, phenylpropionyloxy, phenoxyacetyloxy, phenoxypropionyloxy, naphthoxyacetyloxy, naphthoxypropionyloxy, biphenylacetyloxy, biphenyl Oxyacetyloxy, biphenyloxypropionyloxy, cinnamoyloxy, 4-methoxycinnamoyloxy, benzyloxy, 4-phenoxybenzyloxy, 4-benzyloxybenzyloxy, 3,5-dibenzyloxybenzyloxy, biphenyloxyoxy, 4-methoxybenzyloxy, phenylcarbamoyloxy, biphenylcarbamoyloxy, 4-phenoxyphenylcarbamoyl, etc. Can.

  More preferably, benzoyloxy, 4-methoxybenzoyloxy, 2,4-dimethoxybenzoyloxy, 2,4,5-trimethoxybenzoyloxy, 2,3,4-trimethoxybenzoyloxy, 1-naphthalenecarbonyloxy, 2 -Naphthalenecarbonyloxy, 4-phenoxybenzoyloxy, 4-phenylbenzoyloxy, 4- (4'-methoxyphenoxy) benzoyloxy, 4- (4'-methoxyphenoxy) phenylbenzoyloxy, 4- (2,2-dicyano) Vinyl) benzoyloxy, phenylacetyloxy, phenylpropionyloxy, phenoxyacetyloxy, phenoxypropionyloxy, naphthoxyacetyloxy, naphthoxypropionyloxy, biphenylacetyloxy, biphenyl Alkoxy acetyloxy, biphenyloxy propionyloxy, it can be cited cinnamoyloxyalkyl, 4-methoxy cinnamoyl oxy, and the like.

  Particularly preferably, 1-naphthalenecarbonyloxy, 2-naphthalenecarbonyloxy, 4-phenoxybenzoyloxy, 4-phenylbenzoyloxy, 4- (2,2-dicyanovinyl) benzoyloxy, naphthoxyacetyloxy, naphthoxypropionyloxy Biphenylacetyloxy, biphenyloxyacetyloxy, biphenyloxypropionyloxy, cinnamoyloxy, 4-methoxycinnamoyloxy and the like.

In the present invention, examples of combinations when the substituents substituted as —X ¹⁶ —R ¹⁶ , —X ¹³ —R ¹³ and —X ¹² —R ¹² are not the substituents having the longest absorption are as follows. Preferably, acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, octanoyloxy, cyclohexanecarbonyloxy, methoxy, ethoxy, hydroxyethoxy, hydroxypropoxy, carboxymethoxy, phthalyloxy, methylcarbamoyloxy, ethylcarbamoyloxy And so on.

  More preferred are acetyloxy, propionyloxy and butyryloxy, and particularly preferred is acetyloxy.

In the cellulose compound used in the film of the present invention, substituents at each substitution position substituted at the 2, 3 and 6 positions as -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ¹² , respectively. Although a single group or a different group may be combined, it is more preferable that a substituent having absorption in a long wave and a group having a shorter absorption are combined. That is, in the present invention, a mixed modified cellulose composed of a substituent having absorption in the long wave and a group having absorption shorter than this, and the degree of substitution at the 6-position of the substituent having absorption in the long wave is 2 or 3 Preferred examples include compounds in which the substitution degree of two kinds of substituents is controlled so as to be larger than the total substitution degree.
In the cellulose compound used in the film of the present invention, examples of a preferable combination of a substituent having absorption in a long wave and a group having absorption shorter than this have a group having an aromatic group and an aromatic group. There may be mentioned combinations with no groups.

[Degree of polymerization of cellulose compound]
Degree of polymerization n ¹ of the cellulose compound used in the film of the present invention is not particularly limited, but is preferably 50 to 1,000 with a viscosity average degree of polymerization, more preferably from 100 to 500, particularly preferably from 150 to 350. By setting the degree of polymerization to 1000 or less, the viscosity of the dope solution of the cellulose compound does not become too high, and the film production by casting tends to be easy. Moreover, it is preferable that the degree of polymerization is 50 or more because the strength of the produced film tends to be further improved. The average degree of polymerization can be measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, “Journal of the Textile Society”, Vol. 18, No. 1, pages 105-120, 1962). Specifically, it can be measured according to the method described in JP-A-9-95538.
The molecular weight distribution of the cellulose compound used in the film of the present invention is evaluated by gel permeation chromatography, and the polydispersity index Mw / Mn is preferably 1.5 to 4.0, It is more preferably 1.5 to 3.5, and further preferably 2.0 to 3.5.

Although the preferable example of the cellulose compound represented by general formula (I) below is shown below, this invention is not limited to these specific examples.
The substituent L represents a substituent having absorption at the longest wavelength, and the substituents S1 and S2 represent substituents having absorption at a shorter wavelength than the substituent L. DS ¹² _long , DS ¹³ _long, and DS ¹⁶ _long represent the substitution degrees at the 2nd, 3rd, and 6th positions of the substituent L that absorbs the longest wave, respectively. DS ² , DS ³ and DS ⁶ represent the substitution degrees at the 2-position, 3-position and 6-position of the substituent S1 or S2. The numerical values described in the table indicate the absorption maximum wavelength of a compound in which the portion indicated by * of these substituents is a methyl group.

<Method for producing cellulose compound>
For general methods for producing the cellulose compound used in the film of the present invention, JP-A-6-329561, JP-A-5-240848, Macromol. Chem. Phys., 1996, 197, 953-964, Macromol. Chem. Phys., 2002, 203, 961-967, Org. Biomol. Chem., 2004, 2, 402-407, “Encyclopedia of Cellulose”, pages 131-144, edited by Cellulose Society, 2000, Comprehensive Cellulose Chemistry, Volume 2, Wiley-Vch, 2001, etc. Therefore, the present invention can be applied as appropriate.

The method for producing the cellulose compound used in the film of the present invention can be selected from one-step or multi-step synthesis.
In the one-step synthesis method, synthesis is performed by carrying out esterification or etherification from cellulose. When the cellulose compound used in the film of the present invention is a mixed ester or a mixed ether, an esterifying agent or an ether is used. What is necessary is just to make it react using a 2 or more types of mixture as an agent.
The multi-step synthesis method is a production method in which a synthetic intermediate is once synthesized from cellulose and synthesized as a starting material for the next step. The synthesis in one step is the regioselectivity of a substituent, chemical production suitability, industrial It can be selected when it is not suitable in terms of productivity or economy.
Low-cost compounds such as diacetylcellulose, triacetylcellulose, propionylcellulose, cellulose acetate propionate, and cellulose acetate butyrate are modified by methods such as etherification and esterification (including carbonation esterification and carbamate esterification). This is particularly useful when synthesizing a cellulose compound used in the film of the present invention. In industrial production methods of cellulose compounds, esterification, hydrolysis, depolymerization, etc. may be performed sequentially or simultaneously without taking out intermediates. Such a synthesis method is also a multi-step synthesis. It can be considered a category of law.
In the present invention, a multi-step synthesis method is preferably employed because of the necessity of performing synthesis with controlled substitution positions.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As a cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
When the cellulose raw material is in the form of a sheet or a lump, it is preferably pulverized in advance, and the pulverization is preferably progressed until the cellulose is in the form of cotton, feathers, or powder.

(Activation process)
In the present invention, the cellulose raw material is preferably subjected to a pretreatment (activation) for contacting with an activator. As the activator, carboxylic acid is preferably used for esterification, and water or sodium hydroxide aqueous solution is preferably used for etherification. The addition method can be selected from any method such as spraying, dripping and dipping, and the activation may take any temperature and time.

In the present invention, any arbitrary method may be used as a method for preferentially introducing a specific substituent at the 6-position.
For example, 1) Cellulose or commercially available diacetyl cellulose such as those having a hydroxyl group at the 2, 3, 6 positions are used as raw materials, and the 6 position hydroxyl group is a trityl group, a substituted triphenylmethyl group, or a trialkylsilyl group. A method in which after the protection, a first substituent such as an acetyl group is introduced at the 2nd and 3rd positions, the 6th position is deprotected, and a second substituent is further introduced at the 6th position. For the introduction of regioselective substituents, see, for example, Macromol. Chem. Phys., 2002, 203, 961-967, Org. Biomol. Chem., 2004, 2, 402-407, Carbohydrate Research, 1993, 238, 231-240, JP-A-7-70202, JP-A-7-101858, JP-A-5-240848, etc. There is a description.
2) Using cellulose as a raw material, taking advantage of the relatively high reactivity of the hydroxyl group at the 6-position compared to the 2- and 3-positions, the first substituent was introduced preferentially at the 6-position; A method of introducing a second substituent at the 2nd and 3rd positions.
3) Using a commercially available diacetyl cellulose as a raw material, taking advantage of the relatively high reactivity of the hydroxyl group at the 6-position compared to the 2- and 3-positions, the first substituent is preferentially introduced at the 6-position. how to. Regarding the reactivity of cellulose at positions 2, 3 and 6, the Association for New Chemical Development, Next Generation CC Workshop Phase II Activity Report, July 2004, 2-04-01, Cellulose Society 6th There are descriptions in Annual Meeting Proceedings, page 67 (1999).
4) Using cellulose or commercially available diacetyl cellulose as a raw material, after introducing the first substituent almost evenly at the 2, 3, 6 positions, the first substituent is removed preferentially at the 2, 3 positions, Furthermore, a method of introducing the second substituent at the 2,3-position can be mentioned as a preferred method.

The method 3) is particularly preferable because, for example, commercially available cellulose diacetate (for example, a substitution degree of 1.7 to 2.5) can be used for synthesis in one step.
As a method for preferentially introducing a substituent into the 6-position among the remaining hydroxyl groups of diacetylcellulose, for example, diacetylcellulose is dissolved in an appropriate solvent (acetone, methyl ethyl ketone, ethyl acetate, dichloromethane, chloroform, etc.) and acylated. As an agent, acid halide (for example, benzoic acid chloride, 4-phenylbenzoic acid chloride, cinnamic acid chloride, 4-methoxycinnamic acid chloride, phenylacetic acid chloride, biphenylacetic acid chloride, chromic acid chloride, asalonic acid chloride, etc.) Alternatively, a preferred example is a production method in which an acid anhydride is added together with a base catalyst (pyridine, triethylamine, etc.) while appropriately controlling the reaction temperature and equivalent ratio.

(Filtration)
The reaction mixture (dope) may be filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose compound. Filtration may be performed in any step from the reaction to the reprecipitation of the cellulose compound used in the film of the present invention. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose compound solution thus obtained is mixed in a poor solvent (a solvent containing water, alcohol, etc.), or by mixing the poor solvent in the cellulose compound solution, the cellulose compound is reprecipitated, The objective cellulose compound can be obtained by washing. Reprecipitation may be carried out continuously or batchwise by a fixed amount. In addition, when the sedimentation property varies depending on the temperature, operations such as cooling, heating, and boiling may be performed according to the property. It is also preferable to control the form, apparent density, or molecular weight distribution of the re-precipitated cellulose compound by adjusting the concentration of the cellulose compound solution, the composition of the poor solvent, and the precipitation method according to the substitution mode of the cellulose compound or the degree of polymerization.

(Washing)
The produced cellulose compound is preferably washed. The washing solvent is not particularly limited as long as the solubility of the cellulose compound is low and impurities can be removed, but usually a poor solvent such as water or alcohol is used. The temperature of the cleaning liquid is preferably 15 ° C to 100 ° C, more preferably 25 ° C to 90 ° C, and particularly preferably 30 ° C to 80 ° C. The washing treatment may be performed by a so-called batch method in which filtration and replacement of the washing liquid are repeated, or may be carried out using a continuous washing apparatus. The progress of washing may be traced by any means, but preferable examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum.

(Stabilization)
The cellulose compound after washing is weakly alkaline (for example, carbonates, bicarbonates, hydroxides of sodium, potassium, calcium, magnesium, aluminum, etc.) in order to further improve the stability or reduce the carboxylic acid odor. It is also preferable to treat with an aqueous solution of oxides).
The amount and type of the remaining stabilizer can be controlled by the amount of the cleaning liquid, the cleaning temperature, the time, the stirring method, the form of the cleaning container, the composition and concentration of the stabilizer.

  Although the manufacturing method of the cellulose film of this invention is not specifically limited, It is preferable to manufacture with the melt film forming method or the solution film forming method described below.

<Melting film formation>
The preferable form in the case of manufacturing the cellulose film of this invention by a melt film forming method is demonstrated.

  In the present invention, only one type of cellulose compound may be used, or two or more types may be mixed and used. Moreover, polymeric components other than the cellulose compound used for the film of this invention and various additives can also be mixed suitably. The component to be mixed is preferably one having excellent compatibility with the cellulose compound, and the transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more.

  The melt viscosity at 230 ° C. of the cellulose composition used for melt film formation (the melt viscosity at 230 ° C. of the produced cellulose film) is preferably 150 Pa · s to 1000 Pa · s. Such a melt viscosity can be realized by setting the substituent composition within the range of the present invention, and further adjusting the molecular weight or using an additive described later in combination. If the molecular weight is larger than the preferred range, the melt viscosity becomes too high and film formation may be difficult. On the other hand, if the degree of polymerization is too smaller than the preferred range, the strength as a film will be too low, and the melt viscosity will be too low to allow sufficient shearing during kneading, resulting in insufficient kneading.

  The cellulose compound used in the film of the present invention is added with various additives that can generally be added to the cellulose compound (for example, UV inhibitors, plasticizers, deterioration inhibitors, fine particles, optical property modifiers, etc.). It can be a composition. Moreover, the addition timing of the additive to the cellulose compound represented by the general formula (I) may be added in any of the dope preparation steps, and these additives are added as a preparation step at the end of the dope preparation step. May be added.

(Stabilizer)
In the present invention, it is effective to add a stabilizer in order to maintain the stability of the cellulose compound during high-temperature melt film formation. In particular, it is preferable to add at least one kind of a phenol stabilizer having a molecular weight of 500 or more and at least one selected from a phosphite stabilizer or a thioether stabilizer having a molecular weight of 500 or more. As the preferred phenol-based stabilizer, any known phenol-based stabilizer can be used. Preferable phenolic stabilizers include hindered phenolic stabilizers. Moreover, the stabilizer which has a phenol group and a phosphite group in the same molecule is also mentioned as a preferable material.

(Plasticizer)
If a plasticizer is added to the molten cellulose compound, the crystal melting temperature (Tm) of the cellulose compound can be lowered. Although the molecular weight of the plasticizer used for this invention is not specifically limited, Preferably a high molecular weight plasticizer is mentioned, For example, molecular weight is preferable 500 or more, More preferably, it is 550 or more, Furthermore, 600 or more is preferable. Examples of the plasticizer include phosphate esters, alkylphthalylalkyl glycolates, carboxylic acid esters, and fatty acid esters of polyhydric alcohols. These plasticizers may be solid or oily. That is, the melting point and boiling point are not particularly limited. When performing melt film formation, those having non-volatility can be particularly preferably used.
0-15 mass% of the cellulose compound body used for melt film forming is preferable, as for the addition amount of these plasticizers, 0-10 mass% is more preferable, and 0-8 mass% is especially preferable. These plasticizers may be used in combination of two or more as required.

(UV absorber)
An ultraviolet ray inhibitor may be added to the cellulose composition used for melt film formation. With respect to the ultraviolet ray inhibitor, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-118233. 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173. . The addition amount is preferably 0.01 to 2% by mass, and more preferably 0.01 to 1.5% by mass, based on the melt (melt) to be prepared.

(Fine particles)
In the present invention, it is also preferable to add fine particles to the cellulose composition used for melt film formation.
In the present invention, the fine particles include inorganic compound fine particles or organic compound fine particles, and either one or both of them may be included. The average primary particle size of the fine particles contained in the cellulose compound in the present invention is preferably 5 nm to 3 μm, more preferably 5 nm to 2.5 μm, and particularly preferably 20 nm to 2.0 μm. The addition amount of the fine particles is preferably 0.005 to 1.0% by mass, more preferably 0.01 to 0.8% by mass, and further 0.02 to 0.4% by mass with respect to the cellulose compound. Particularly preferred. In the present invention, “average primary particle size” refers to the particle size of fine particles in a dispersed state (non-aggregated state), and the average primary particle size is determined by dynamic light scattering (several nm to 1 μm), laser diffraction (0 0.1 μm to several thousand μm) and a laser diffraction / scattering method (several tens of nm to 1 μm) based on the Mie theory.

Preferable examples of the inorganic compound fine particles include SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , V ₂ O ₅ , talc, clay, Examples include calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Preferably, at least one of SiO ₂ , ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ , In ₂ O ₃ , MgO, BaO, MoO ₂ , and V ₂ O ₅ is preferable, and SiO ₂ is more preferable. , TiO ₂ , SnO ₂ , Al ₂ O ₃ , ZrO ₂ .

  Preferable examples of the organic compound fine particles include polymers such as silicone resins, fluorine resins, and acrylic resins, and silicone resins are particularly preferable. As the silicone resin, those having a three-dimensional network structure are preferable. For example, trade names such as Tospearl 103, 105, 108, 120, 145, 3120 and 240 (above, manufactured by Toshiba Silicone) A commercially available product having can be used.

Furthermore, the fine particles comprising an inorganic compound are preferably surface-treated in order to stably exist in the cellulose composition and the film.
The fine particles may be mixed with the cellulose compound in any step of film formation. Among the steps for producing the cellulose compound, the fine particles are added in any step before reprecipitation, and are reconstituted in a state containing the fine particles. It is also preferred to precipitate.

(Release agent)
The cellulose composition used for melt film formation preferably contains a compound having a fluorine atom. The compound having a fluorine atom can exhibit an action as a release agent, and may be a low molecular weight compound or a polymer. Examples of the polymer include the polymers described in JP-A No. 2001-269564. Preferred as the polymer having a fluorine atom is a polymer obtained by polymerizing a monomer containing an ethylenically unsaturated monomer containing a fluorinated alkyl group as an essential component. The fluorinated alkyl group-containing ethylenically unsaturated monomer related to the polymer is not particularly limited as long as it is a compound having an ethylenically unsaturated group and a fluorinated alkyl group in the molecule. A surfactant having a fluorine atom can also be used, and a nonionic surfactant is particularly preferable.

(Pelletized)
The cellulose compound and additives are preferably mixed and pelletized prior to melt film formation.
Pelletization can be performed by melting the cellulose compound and additives at 150 ° C. to 250 ° C. using a biaxial or uniaxial kneading extruder, and then solidifying and cutting the noodle-shaped extrudate. Pelletization may be performed by an underwater cut method in which the material is cut while being extruded directly into water. More preferably, the kneading and extruding machine is a vent type and is pelletized while decompressing. Further, it is more preferable to pelletize the inside of the kneading extruder while substituting with nitrogen.

(Specific method of melt film formation)
Below, the specific method of melt film forming is demonstrated.
(1) Drying It is preferable to dry the moisture in the pellets prior to melt film formation. A preferable moisture content is 0.1 mass% or less, More preferably, it is 0.01 mass% or less.

(2) Melt extrusion The dried cellulose compound resin is supplied into the cylinder from the supply port of the extruder.
The screw compression ratio of the extruder is preferably 2.5 to 4.5, more preferably 3.0 to 4.0. L (screw length) / D (screw diameter) is preferably 20 to 70. More preferably, it is 24-50. The melting temperature is preferably performed at the above-described temperature.
In order to prevent the oxidation of the resin, it is more preferable that the inside of the extruder is carried out in an inert (nitrogen or the like) air stream or while being evacuated using a vented extruder.

(3) Filtration It is preferable to perform breaker plate type filtration at the exit of the extruder.
For high-precision filtration, it is preferable to provide a leaf type disk filter type filtration device after passing through the gear pump. Filtration may be performed in a single stage or in multiple stages.

(4) Gear pump It is preferable to install a gear pump between the extruder and the die in order to improve the thickness accuracy (reduction in fluctuation of the discharge amount). Moreover, it is preferable for the extrusion pressure stabilization to reduce the temperature fluctuation of the adapter connecting the extruder and the gear pump, the gear pump and the die.

(5) Die As long as the molten resin stays in the die, any type of commonly used T-die, fishtail die, and hanger coat die may be used. It is also preferable to insert a static mixer for improving the uniformity of the resin temperature immediately before the T die.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 4 minutes to 30 minutes.

(6) Casting The molten resin extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film. At this time, it is also preferable to use a touch roll.
It is preferable to use 1 to 8 casting drums, more preferably 2 to 5 casting drums, and slowly cool them. Then, it peels off from a casting drum, winds up after passing through a nip roll. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 50 μm to 200 μm.

(7) Winding It is preferable to trim both ends before winding. The trimmed portion may be reused as a film raw material. The take-up tension may be taken up with a constant take-up tension, but it is more preferable that the take-up tension is tapered and taken up according to the take-up diameter. Further, the draw ratio between the nip rolls may be adjusted so that the film is not subjected to a tension higher than a specified value in the middle of the line.
Prior to winding, a laminate film may be attached to at least one side.

The residual organic solvent amount of the cellulose film of the present invention is preferably 0.03% by mass or less, more preferably 0.02% or less, and particularly preferably 0.01% or less. When the residual solvent is in such a range, it is preferable that the odor of the solvent is not generated and the characteristic change of the film due to the evaporation of the solvent hardly occurs. The melt film forming method is an effective method for reducing the residual solvent.
The amount of the residual solvent can be measured by a gas chromatography method or the like.

<Solution casting>
Next, the preferable form in the case of manufacturing the cellulose film of this invention with a solution casting method is demonstrated.
In the present invention, the solvent of the cellulose compound is not particularly limited as long as the cellulose compound can be dissolved, cast, and formed into a film, and the object can be achieved. Preferred solvents include chlorinated organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, tetrachloroethylene, and non-chlorinated organic solvents.

  The chlorinated organic solvent used in the present invention is not particularly limited as long as the object can be achieved as long as the cellulose compound can be dissolved, cast and film-formed. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane.

  Although it does not specifically limit about the non-chlorine type organic solvent used together with the chlorinated organic solvent which is a main solvent, Methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, a dioxane, the number of carbon atoms is 4-7. Selected from ketones or acetoacetates, alcohols having 1 to 10 carbon atoms or hydrocarbons. Preferred non-chlorine organic solvents used in combination are methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. , 2-butanol, and cyclohexanol, cyclohexane, and hexane.

  The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The cellulose compound used in the film of the present invention is preferably dissolved in an organic solvent in an amount of 5 to 35% by mass. More preferably, it is 10-30 mass%, and it is especially preferable that it is the cellulose compound solution which melt | dissolved 12-28 mass%. The method of carrying out the cellulose compound at these concentrations may be carried out so that the cellulose compound has a predetermined concentration at the stage of dissolution, or is prepared in advance as a low concentration solution (for example, 4 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. Furthermore, after adding a high concentration cellulose compound solution in advance, various additives may be added to obtain a predetermined low concentration cellulose compound solution, and the cellulose compound solution concentration used in the film of the present invention is obtained by any method. If implemented, there is no particular problem.

  Regarding the preparation of the cellulose compound solution (dope) used in the film of the present invention, the dissolution method is not particularly limited, and may be room temperature, and further, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. . With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A-2000-273184, JP-A-11-323017, JP-A-11-302388 and the like describe methods for preparing a cellulose acylate solution. The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. The details of these methods, particularly for non-chlorine-based solvent systems, are described in detail on pages 22 to 25 of the Japan Institute of Invention Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). Will be implemented. Further, the cellulose compound solution used in the film of the present invention is usually concentrated and filtered, and similarly, published by the Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Invention Association), page 25. Are described in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

  The cellulose compound solution used for the film of the present invention preferably has a viscosity and a dynamic storage elastic modulus within the range. As a method for measuring the viscosity and the dynamic storage elastic modulus in this specification, 1 mL of a sample solution is measured using a rheometer (CLS 500) with a Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured by varying the range from 40 ° C. to −10 ° C. at 2 ° C./min using an Oscillation Step / Temperature Ramp, static non-Newtonian viscosity n * (Pa · s) at 40 ° C., and storage at −5 ° C. The elastic modulus G ′ (Pa) is obtained. The sample solution is preliminarily kept at the measurement start temperature until the liquid temperature becomes constant, and then the measurement is started. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. It is preferable that the dynamic storage elastic modulus at 15 ° C. is 100 to 1,000,000. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When a body is -50 degreeC, it is preferable that the dynamic storage elastic modulus in -50 degreeC is 10,000-5 million Pa.

(Specific method of solution casting)
Next, the manufacturing method of the cellulose film of this invention is described. As the method and equipment for producing the cellulose film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose acylate film are used. The dope (cellulose compound solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressurizing die through a pressurizing quantitative gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of revolutions. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. In many cases, a coating device is added to the surface processing of the film. Each of these manufacturing processes is described in detail on pages 25 to 30 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). Including), metal support, drying, peeling, stretching, etc.

  Here, although the space temperature of a casting part is not specifically limited in this invention, It is preferable that it is -50-50 degreeC. Furthermore, it is preferable that it is -30-40 degreeC, and it is especially preferable that it is -20-30 degreeC. In particular, the cellulose compound solution cast by the space temperature at a low temperature can hold the film containing the organic solvent by instantly cooling on the support and increasing the gel strength. Thereby, without evaporating the organic solvent from the cellulose compound, it can be peeled off from the support in a short time, and high-speed casting can be achieved. The means for cooling the space may be normal air, nitrogen, argon, helium or the like, and is not particularly limited. In that case, the relative humidity is preferably 0 to 70%, more preferably 0 to 50%. Moreover, in this invention, the temperature of the support body of the casting part which casts a cellulose compound solution is -50-130 degreeC, Preferably it is -30-25 degreeC, Furthermore, it is -20-15 degreeC. In order to keep the casting part at the temperature of the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device may be arranged in the casting part to cool the space. At this time, it is important to take care not to attach water, and it can be carried out by a method such as using dry gas.

  In the present invention, the following configurations are particularly preferred for the contents and casting of each layer. That is, the cellulose compound solution is a cellulose compound solution containing 0.1 to 20% by mass of at least one liquid or solid plasticizer with respect to the cellulose compound at 25 ° C. and / or at least one kind. A cellulose compound solution containing 0.001 to 5% by mass of a liquid or solid UV absorber based on the cellulose compound, and / or an average particle size of 5 to 3000 nm of at least one solid. It is a cellulose compound solution containing 0.001 to 5% by mass of a certain fine particle powder with respect to the cellulose compound, and / or 0.001 to 0.001 of at least one fluorosurfactant with respect to the cellulose compound. And / or at least one cellulose compound solution containing 2% by weight It is a cellulose compound solution containing 0.0001 to 2% by mass of a release agent with respect to the cellulose compound, and / or 0.0001 to 2% by mass of at least one kind of deterioration preventing agent with respect to the cellulose compound. And / or containing at least one optical anisotropy control agent in an amount of 0.1 to 15% by mass with respect to the cellulose compound, and / or at least one red component. It is preferably a cellulose compound solution characterized by being a cellulose compound solution containing 0.1 to 5% by mass of an outer absorbent with respect to the cellulose compound, and a cellulose film produced therefrom.

  In the casting step, one type of cellulose compound solution may be cast as a single layer, or two or more types of cellulose compound solutions may be cast simultaneously and / or sequentially. In the case of having a casting process comprising two or more layers, in the produced cellulose compound solution and cellulose film, the composition of the chlorinated solvent in each layer is either the same or different, and the additive for each layer Is one type or a mixture of two or more types, the addition position of the additive to each layer is either the same layer or a different layer, in the additive solution Each layer has the same or different concentration in each layer, the aggregate molecular weight of each layer is the same or different aggregate molecular weight, and the temperature of the solution in each layer is the same The temperature of each layer is the same or different, and the viscosity of each layer is the same or different It is either one, the thickness of each layer after drying is either the same or different thickness, and the materials present in each layer are the same state or distribution or different state or distribution A cellulose compound solution characterized in that the physical properties of each layer are either the same or different physical properties, and the physical properties of each layer are either uniform or a distribution of different physical properties, and A cellulose film prepared from a solution is also preferable. Here, the physical properties include physical properties described in detail on pages 6 to 7 of the Japan Society of Invention Public Technical Report (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Inventions). Haze, transmittance, spectral properties, retardation Re, Rth, molecular orientation axis, axial misalignment, tear strength, bending strength, tensile strength, roll-in / out Rt difference, creaking, dynamic friction, alkali hydrolysis, curl value, moisture content , Residual solvent amount, heat shrinkage rate, high humidity dimensional evaluation, moisture permeability, base flatness, dimensional stability, heat shrinkage start temperature, elastic modulus, and measurement of bright spot foreign matter, and base evaluation The impedance and surface shape used in the above are also included. In addition, the Yellow Index, Transparency, Thermophysical Properties (Tg, Crystallization) of Cellulose Compounds, which are described in detail on page 11 of the Japan Institute of Invention Technology (Publication No. 2001-1745, published on March 15, 2001, Invention Association) Heat).

<Treatment of cellulose film>
(Stretching)
As described above, the cellulose film of the present invention produced by the melt film forming method or the solution film forming method can be stretched for the purpose of improving the surface shape, expressing Re, Rth, improving the linear expansion coefficient, and the like. preferable.
Stretching may be performed on-line during the film forming process, or may be performed off-line after winding up once after film formation is completed. That is, in the case of solution casting, the stretching may be performed in a state where drying of the solvent during film formation is not completed, or may be performed after completion of drying. In the case of melt film formation, stretching may be performed in a state where cooling during film formation is not completed, or may be performed after completion of cooling.
The stretching is preferably performed at a glass transition temperature Tg to (Tg + 50 ° C.), more preferably (Tg + 1 ° C.) to (Tg + 30 ° C.), and particularly preferably (Tg + 2 ° C.) to (Tg + 20 ° C.). A preferable draw ratio is 0.1% to 500%, more preferably 10% to 300%, and particularly preferably 30% to 200%. These stretching operations may be performed in one stage or in multiple stages. The draw ratio here is determined using the following equation.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching

Such stretching is performed by longitudinal stretching, lateral stretching, and combinations thereof. Longitudinal stretching includes (1) roll stretching (stretching in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side), (2) fixed end stretching (holding both ends of the film, And the like can be used. Further, for the transverse stretching, tenter stretching (stretching by stretching both sides of the film with a chuck and stretching it in the transverse direction (perpendicular to the longitudinal direction)) can be used. These longitudinal stretching and lateral stretching may be performed alone (uniaxial stretching) or in combination (biaxial stretching). In the case of biaxial stretching, it may be carried out in the longitudinal and transverse sequential manners (sequential stretching) or simultaneously (simultaneous stretching).
The stretching speed of longitudinal stretching and lateral stretching is preferably 10% / min to 10000% / min, more preferably 20% / min to 1000% / min, particularly preferably 30% / min to 800% / min. In the case of multistage stretching, the average value of the stretching speed of each stage is indicated.

Following such stretching, it is also preferable to relax by 0 to 10% in the longitudinal or transverse direction. Furthermore, it is also preferable to heat-fix at 150-250 degreeC for 1 second-3 minutes following extension.
Thus, the film thickness after extending | stretching has 10-300 micrometers, 20-200 micrometers is more preferable, 30-100 micrometers is especially preferable.

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

  In order to suppress light leakage when the polarizing plate is viewed obliquely, it is necessary to arrange the transmission axis of the polarizing film and the slow axis in the plane of the cellulose film in parallel. Since the transmission axis of the roll film-like polarizing film produced continuously is generally parallel to the width direction of the roll film, the protective film is composed of the roll film-like polarizing film and the roll film-like cellulose film. In order to continuously bond the film, the in-plane slow axis of the roll film-like protective film needs to be parallel to the width direction of the film. Therefore, it is preferable to stretch more in the width direction. The stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched. In the former case, stretching may be performed in a state containing a residual solvent, and the stretching can be preferably performed at a residual solvent amount of 2 to 30% by mass.

  The thickness of the cellulose film preferably used in the present invention obtained after drying varies depending on the purpose of use, is preferably in the range of 5 to 500 μm, more preferably in the range of 20 to 300 μm, and 30 to 150 μm. More preferably, it is in the range. Moreover, it is preferable that it is 40-110 micrometers for optical use, especially for VA liquid crystal display devices. The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

  The width of the cellulose film obtained as described above is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, and still more preferably 0.8 to 2.2 m. The length is preferably 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, it is preferable to give a knurling to at least one end, the knurling width is preferably 3 to 50 mm, more preferably 5 to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

  The above-mentioned unstretched or stretched cellulose film may be used alone, or may be used in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) or hard A coat layer may be provided for use.

<Optical properties of cellulose film>
The cellulose film of the present invention preferably satisfies the following formulas (i) and (ii).
Formula (i): 0 nm ≦ Re ≦ 700 nm
Formula (ii): 0 nm ≦ Rth ≦ 2000 nm
Re is more preferably 20 nm to 600 nm, and particularly preferably 50 nm to 300 nm. Rth is more preferably 20 nm to 1500 nm, and particularly preferably 50 nm to 1000 nm.
The cellulose compound used in the film of the present invention has a large retardation (Re, Rth) expression by substituting the group of the present invention at the 6-position. By appropriately selecting the method for producing the cellulose film and the stretching method of the present invention, the expression of Re and Rth may be arbitrarily controlled within the above preferred range.

[Retardation]
Each retardation in the present invention will be described. In this specification, Re and Rth (unit: nm) are determined according to the following method. First, the film was conditioned at 25 ° C. and 60% relative humidity for 24 hours, and then a prism coupler (MODEL2010 Prism Coupler: manufactured by Metricon) was used. At 25 ° C. and 60% relative humidity, the following formula was used: An average refractive index (n) represented by (a) is obtained.
Formula (a): n = (n _TE × 2 + n _TM ) / 3
[ _Where n _TE is a refractive index measured with polarized light in the film plane direction, and n _TM is a refractive index measured with polarized light in the film surface normal direction. ]

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotary axis) (if there is no slow axis, any in-plane film In total, measurement is performed at 11 points by injecting light of wavelength λ nm from each inclined direction in steps of −50 ° to + 50 ° from the normal direction to the normal direction of the film (with the direction of the rotation axis as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value.
In the above, there is no description regarding λ, and when only Re and Rth are described, it represents a value measured using light having a wavelength of 590 nm. In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. Is calculated in KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (b) and (c).

  In the formula (b), Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) as the slow axis (indicated by KOBRA 21ADH or WR) as the tilt axis (rotation axis). Measured at 11 points by making light of wavelength λ nm incident from each inclined direction in 10 degree steps, and KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index and input film thickness value. To do.
By inputting these average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  The variation in Re (590) value in the width direction of the film is preferably ± 5 nm, more preferably ± 3 nm. Further, the variation in the Rth (590) value in the width direction is preferably ± 10 nm, and more preferably ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

Re (λ) value and Rth (λ) value satisfy the following formulas (V) and (VI), respectively, to widen the viewing angle of liquid crystal display devices, particularly VA mode and OCB mode liquid crystal display devices. Is preferred. In particular, a cellulose film is preferable when used as a protective film on the liquid crystal cell side of the polarizing plate.
Formula (V): 0 nm ≦ Re (590) ≦ 200 nm
Formula (VI): 0 nm ≦ Rth (590) ≦ 400 nm
(In the formula, Re (590) and Rth (590) are values (unit: nm) at the wavelength λ = 590 nm.)
More preferably,
Formula (V-I): 30 nm ≦ Re (590) ≦ 150 nm
Formula (VI-I): 30 nm ≦ Rth (590) ≦ 300 nm

The cellulose compound used in the film of the present invention has a high retardation development property at the same stretch ratio. Therefore, the film thickness is reduced, it is applied to a cellulose acetate film, or mixed with cellulose acetate to form a film. When the cellulose film of the present invention is used for the VA mode and the OCB mode, a mode in which a total of two sheets are used on both sides of the cell (two sheets type) and only one of the upper and lower sides of the cell There are two types of forms to be used (single sheet type).
In the case of the two-sheet type, Re (590) is preferably 20 to 100 nm, and more preferably 30 to 70 nm. Rth (590) is preferably from 70 to 300 nm, more preferably from 100 to 200 nm.
In the case of a single sheet type, Re (590) is preferably 30 to 150 nm, and more preferably 40 to 100 nm. Rth (590) is preferably from 100 to 300 nm, more preferably from 150 to 250 nm.

[Haze]
In the cellulose film of the present invention, for example, a value measured using a haze meter (1001DP type, manufactured by Nippon Denshoku Industries Co., Ltd.) is preferably 0.1 or more and 0.8 or less, and 0.1 or more. It is more preferably 0.7 or less, and particularly preferably 0.1 or more and 0.60 or less. 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 film.

(Photoelastic coefficient)
The cellulose film of the present invention is preferably used as a polarizing plate protective film or a retardation plate. When used as a polarizing plate protective film or a retardation plate, the birefringence (Re, Rth) may change due to the stress due to expansion and contraction due to moisture absorption. The change in birefringence due to such stress can be measured as a photoelastic coefficient, and the range is preferably 5 × 10 ⁻⁷ (cm ² / kgf) to 30 × 10 ⁻⁷ (cm ² / kgf), and 6 More preferably, it is preferably 10 × 10 ⁻⁷ (cm ² / kgf) to 25 × 10 ⁻⁷ (cm ² / kgf), and 7 × 10 ⁻⁷ (cm ² / kgf) to 20 × 10 ⁻⁷ (cm ² / kgf). It is particularly preferred.

(surface treatment)
The unstretched or stretched cellulose film can be subjected to surface treatment according to circumstances, thereby achieving improved adhesion between the cellulose film and each functional layer (for example, the undercoat layer and the back layer). For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low pressure gas of 10 ^{−3 to} 20 Torr, 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 includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute 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 film.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the immersion method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 minutes to 10 minutes, followed by neutralization, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. 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 during the 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 acid, and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP 2002-82226 A and WO 02/46809 pamphlet.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be applied after the above surface treatment or may be applied without the surface treatment. The details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

<Combination with functional layer>
The cellulose film of the present invention may be combined with the functional layer described in detail on pages 32 to 45 of the Japan Institute of Invention Disclosure Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). preferable. Among these, application of a polarizing film (formation of a polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

[Polarizing film]
(Polarized film material)
At present, commercially available polarizing films are generally made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. is there. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used.
The iodine and the dichroic dye in the polarizing film develop polarizing performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (for example, sulfo, amino, hydroxyl). For example, the compounds described in page 58 of the Japan Society for Invention Disclosure Technique (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society for Invention) are mentioned.

  As the binder of the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913, Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like are included. Silane coupling agents can be used as the polymer.

Of these, water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are preferable. Further preferred. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%.
It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.
The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), more preferably 25 μm or less, and particularly preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (for example, boric acid and borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.

  Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

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

(A) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is usually 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of usually 15 to 50 ° C., preferably 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be performed by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip rolls to be higher than that of the preceding nip rolls. The stretching ratio (after stretching / the length ratio in the initial state: the same hereinafter) is 1.2 to 3.5 times, more preferably 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. Then, it is made to dry at 50 to 90 degreeC, and a polarizing film is obtained.

(B) Diagonal Stretching Method The oblique stretching method can be carried out by stretching using a tenter extending in the tilting direction, as described in JP-A-2002-86554. Since this stretching is performed in the air, it is necessary to make the film easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The relative humidity is preferably 50% to 100%, more preferably 70% to 100%, and particularly preferably 80% to 100%. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.

After the end of stretching, the film is preferably dried at 50 to 100 ° C., more preferably 60 to 90 ° C., preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and particularly preferably substantially 45 ° (40 ° to 50 °).

(Lamination)
The saponified cellulose film and a polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably performed so that the casting axis direction of the cellulose film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.

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

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

[Application of optical compensation layer (production of optical compensation sheet)]
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the cellulose film and further provides the optically anisotropic layer. Formed with.

(Alignment film)
An alignment film is provided on the surface-treated cellulose film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after the alignment of the liquid crystalline compound, the alignment film plays the role and is not necessarily an essential component. That is, it is also possible to produce a polarizing plate using the cellulose film of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.

  The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, the crosslinkability has a function of bonding side chains having a crosslinkable functional group (for example, a double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph [0022] of JP-A-8-338913, for example. ), Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are particularly preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state.

  For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy groups, dialkoxy groups, monoalkoxy groups), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426, for example. Etc.

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

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

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

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

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

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

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

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

(Optically anisotropic layer)
Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

1) Rod-like liquid crystalline molecules As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.

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

2) Discotic liquid crystalline molecules Discotic liquid crystalline molecules include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990). Kohne et al., Angew. Chem., 96, 70 (1984) and the cyclohexane derivatives described in J. Chem. M. Lehn et al. Chem. Commun., 1794 (1985); Zhang et al. Am. Chem. Soc., 116, 2655 (1994), including azacrown and phenylacetylene macrocycles.

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

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] of JP-A No. 2000-155216.

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

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

(Other composition of optically anisotropic layer)
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the liquid crystal molecules have compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer, and the thing which shows copolymerizability with respect to the liquid crystal compound which has said polymeric group is preferable. Examples thereof include those described in paragraph numbers [0018] to [0020] of JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1% by mass to 50% by mass and preferably in the range of 5% by mass to 30% by mass with respect to the discotic liquid crystalline molecules.

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

  The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.

  A cellulose compound can be mentioned as an example of a polymer. Preferable examples of the cellulose compound include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1% by mass to 10% by mass with respect to the liquid crystalline molecule so as not to inhibit the alignment of the liquid crystal molecules. It is more preferable that it is in the range.

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

(Formation of optically anisotropic layer)
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerization initiator described later and optional components on the alignment film.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 1 to 10 μm.

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

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448,828). Description), α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758). ), A combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compound (Japanese Patent Laid-Open No. 60-105667), U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in U.S. Pat. No. 4,212,970).

The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, and particularly preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

(Combination with polarizing film)
It is also preferable to combine this optical compensation film and a polarizing film. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When a polarizing plate using the cellulose film of the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

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

[Addition of antireflection layer (production of antireflection film)]
The antireflection film generally supports a low refractive index layer which is also an antifouling layer and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer). It is provided on the body.
As a method of forming a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes are laminated, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or a sol-gel method of a metal compound such as a metal alkoxide. Examples thereof include a method of forming a thin film by forming a colloidal metal oxide particle film after post-treatment (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310).

On the other hand, various antireflection films in which thin films are laminated by applying a dispersion in which inorganic particles are dispersed in a matrix have been proposed as antireflection films having high productivity. Examples of the antireflection film by application include an antireflection film in which a layer provided with an antiglare property having fine irregularities on the surface is formed on the uppermost layer.
The cellulose film of the present invention can be applied to the antireflection film produced by any of the above methods, but is particularly preferably applied to the antireflection film produced by a coating method (coating type).

(Layer structure of coating type antireflection film)
An antireflection film consisting of a layer structure in which at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) are sequentially formed on a transparent support is designed so that the refractive index satisfies the following relationship: The
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. May be. Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer. Examples thereof include those described in 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 etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, and more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and particularly preferably 3H or more 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 inorganic compounds 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, a technique for treating the surface of the particles with a surface treatment agent (for example, described in JP-A Nos. 11-295503, 11-153703, and 2000-9908). Technology that treats with a silane coupling agent, technology that treats with an anionic compound or organometallic coupling agent described in JP 2001-310432 A, etc., technology that makes a core-shell structure with high refractive index particles as a core (For example, a technique described in JP-A-2001-166104), a technique using a specific dispersant (for example, JP-A-11-153703, US Pat. No. 6,210,858B1, JP-A-2002) Technology described in Japanese Patent Application Publication No. 2776069, etc. can be used. Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

Further, the composition is selected from a composition containing a polyfunctional compound having at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound having a hydrolyzable group, and a composition of a partial condensate thereof. At least one composition is preferred. Examples of the compounds used in these compositions 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, a curable film described in JP 2001-293818 A can be exemplified.

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.

(Low refractive index layer)
The low refractive index layer is a layer formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is generally 1.20 to 1.55. Preferably it is 1.30-1.50.
The low refractive index layer is preferably constructed as an outermost layer having scratch resistance and antifouling properties. In order to greatly improve the scratch resistance, it is effective to impart slipperiness to the surface. Specifically, a conventionally known method for forming a thin film layer in which a silicone compound or a fluorine-containing compound is introduced 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. Moreover, it is preferable that a fluorine-containing compound is a compound containing the crosslinkable or polymerizable functional group which contains a fluorine atom in 35-80 mass%.

For example, paragraph numbers [0018] to [0026] of JP-A-9-222503, paragraph numbers [0019] to [0030] of JP-A-11-38202, and paragraph number [0027] of JP-A-2001-40284. To [0028], and compounds described in JP-A No. 2000-284102.
The silicone compound is a compound having a polysiloxane structure, and preferably has a curable functional group or a polymerizable functional group in the polymer chain and forms a crosslinked structure in the film. For example, reactive silicone (for example, Silaplane (manufactured by Chisso Corporation), etc.), polysiloxane having 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 carried out by light irradiation at the same time as or after coating the coating composition for forming the outermost layer containing a polymerization initiator or a sensitizer. It is preferable to carry out by heating.
Also preferred is a sol-gel cured film obtained by curing an organometallic compound such as a silane coupling agent and a silane coupling agent having a specific fluorine-containing hydrocarbon group by 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). And the like described in JP-A-53804).

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 particularly preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer can be provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the 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 organometallic compound having a hydrolyzable functional group 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 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 in the description of 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 particularly 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 amount of wear of the test piece before and after the test, the better.

(Forward scattering layer)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. The technique described in -107512 gazette etc. can be used.

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

(Application method)
Each layer of the antireflection film is formed by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, micro gravure method or extrusion coating method (US Pat. No. 2,681,294). According to the specification, it can be formed by coating.

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

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

<Liquid crystal display device>
The cellulose film of the present invention, the polarizing plate using the cellulose film, the retardation film and the optical film can be preferably incorporated in a liquid crystal display device. Examples of the liquid crystal display device include TN type, IPS type, FLC type, AFLC type, OCB type, STN type, ECB type, VA type and HAN type display devices. The cellulose film of the present invention can be preferably used in any of transmissive, reflective and transflective liquid crystal display devices. Each liquid crystal mode will be described below.

(TN type liquid crystal display device)
The cellulose film of the present invention may be used as a support for an optical compensation sheet of a TN type liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation sheet used in the TN type liquid crystal display device can be produced according to the descriptions in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. it can. In addition, the papers of Mori et al. (Jpn. J. Appl. Phys., Vol. 36 (1997) p. 143, Jpn. J. Appl. Phys., Vol. 36 (1997) p. 1068). It can be made according to the description.

(STN type liquid crystal display device)
The cellulose film of the present invention may be used as a support for an optical compensation sheet of an STN type liquid crystal display device having an STN mode liquid crystal cell. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation sheet used in the STN type liquid crystal display device can be produced according to the description in JP-A-2000-105316.

(VA type liquid crystal display device)
The cellulose film of the present invention is particularly advantageously used as a support for an optical compensation sheet of a VA liquid crystal display device having a VA mode liquid crystal cell. The Re value of the optical compensation sheet used in the VA liquid crystal display device is preferably 0 to 150 nm and the Rth value is preferably 70 to 400 nm. When two optically anisotropic polymer films are used for the VA liquid crystal display device, the Rth value of the film is preferably 70 to 250 nm. When one optically anisotropic polymer film is used for the VA liquid crystal display device, the Rth value of the film is preferably 150 to 400 nm. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576.

(IPS liquid crystal display device, ECB liquid crystal display device)
The cellulose film of the present invention is also suitably used as an optical compensation sheet for an IPS liquid crystal display device or an ECB liquid crystal display device having an IPS mode or ECB mode liquid crystal cell, or a protective film for a polarizing plate. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage. In these embodiments, the polarizing plate using the cellulose film of the present invention contributes to the improvement of the color tone, the expansion of the viewing angle, and the improvement of the contrast. In this embodiment, among the protective films for the polarizing plates above and below the liquid crystal cell, the polarizing film using the cellulose film of the present invention for the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate. It is preferable to use the plate on at least one side. More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is not more than twice the value of Δn · d of the liquid crystal layer. It is preferable to set to.

(OCB type liquid crystal display device, HAN type liquid crystal display device)
The cellulose film of the present invention is also advantageously used as a support for an optical compensation sheet of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. In the optical compensation sheet used for the OCB type liquid crystal display device or the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of the retardation value is minimum does not exist in the plane of the optical compensation sheet or in the normal direction. The optical properties of the optical compensation sheet used in the OCB type liquid crystal display device or the HAN type liquid crystal display device are also the optical properties of the optical anisotropic layer, the optical properties of the support, and the optical anisotropic layer and the support. Is determined by the arrangement of An optical compensation sheet used for an OCB type liquid crystal display device or a HAN type liquid crystal display device can be produced according to the description in JP-A-9-197397. It can also be prepared according to the description of Mori et al. (Jpn. J. Appl. Phys., Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The cellulose film of the present invention is also advantageously used as an optical compensation sheet for TN-type, STN-type, HAN-type, and GH (Guest-Host) type reflective liquid crystal display devices. These display modes have been well known since ancient times. The TN-type reflective liquid crystal display device can be manufactured according to the descriptions in JP-A-10-123478, International Publication WO98 / 48320, and Patent Registration No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device can be produced according to the description in International Publication WO00 / 65384.

(Other liquid crystal display devices)
The cellulose film of the present invention is also advantageously used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell in ASM (Axial Symmetrical Microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device can be manufactured according to the description of Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).

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

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

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

  According to the present invention, it is possible to obtain a cellulose film that can be suitably used as an optical film and has a wide retardation expression region and good humidity dependency. Furthermore, by using the cellulose film, a high-quality retardation film, polarizing plate, optical compensation film, antireflection film and image display device can be obtained.

Hereinafter, the features of the present invention will be described more specifically with reference to Examples and Comparative Examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.
The average degree of polymerization was measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962).

Reference example (preparation of cellulose compound)
Synthesis Example 1 Preparation of Illustrative Compound A-1 50 parts by mass of diacetylcellulose (acetyl substitution degree 2.16) was dissolved in 500 parts by mass of acetone. To this, 23 parts by mass of pyridine was added, and the internal temperature was cooled to 5 ° C. 60 parts by mass of 4-phenylbenzoic acid chloride dissolved in 200 parts by mass of acetone in advance was added dropwise over 30 minutes, and the mixture was stirred at 10 ° C. or lower for 1 hour. .
100 parts by mass of methanol was added and stirred for 30 minutes. The reaction mixture was mixed with methanol to precipitate the cellulose compound and purified by continuous washing with methanol at 40 to 50 ° C.
After filtration, it was vacuum-dried to obtain 60 parts by mass of exemplary compound A-1. The average degree of polymerization was 255.

Synthesis Example 2 Preparation of Exemplary Compound A-2 50 parts by mass of diacetylcellulose (acetyl substitution degree 2.16) was dissolved in 500 parts by mass of acetone. To this, 23 parts by mass of pyridine was added, and the internal temperature was cooled to 5 ° C. 55 parts by mass of 4-methoxycinnamic chloride previously dissolved in 200 parts by mass of acetone was added dropwise over 30 minutes, and the mixture was stirred at 10 ° C. or less for 1 hour, then the internal temperature was raised to 40 ° C. and further stirred for 4 hours. .
100 parts by mass of methanol was added and stirred for 30 minutes. The reaction mixture was mixed with methanol to precipitate the cellulose compound and purified by continuous washing with methanol at 40 to 50 ° C.
After filtration, it was vacuum-dried to obtain 61 parts by mass of Exemplified Compound A-2. The average degree of polymerization was 250.

Synthesis Example 3 Preparation of Exemplary Compound A-13 50 parts by mass of cellulose acetate propionate (acetyl substitution degree 0.29, propionyl substitution degree 1.70) was dissolved in 500 parts by mass of acetone. To this was added 27 parts by mass of pyridine, and the internal temperature was cooled to 5 ° C. 20 parts by mass of benzoyl chloride previously diluted with 200 parts by mass of acetone was added dropwise over 30 minutes, and the mixture was stirred at 10 ° C. or lower for 1 hour, and then the internal temperature was raised to 40 ° C. and further stirred for 4 hours.
100 parts by mass of methanol was added and stirred for 30 minutes. The reaction mixture was mixed with methanol to precipitate the cellulose compound and purified by continuous washing with methanol at 40 to 50 ° C.
After filtration, it was vacuum dried to obtain 55 parts by mass of Exemplified Compound A-13. The average degree of polymerization was 275.

Other exemplary compounds used in the examples were synthesized in the same manner as in Example 1. For the compound used in Example 1, —X ¹⁶ —R ¹⁶ , —X ¹³ —R ¹³ and —X ¹² —R ¹² were changed to CH ₃ —X ¹⁶ —R ¹⁶ , CH ₃ —X ¹³ —R ¹³ and CH _3. The molar extinction coefficient at the longest absorption maximum at 270 to 450 nm in the solution in the case of -X ¹² -R ¹² is A-1: 6500 (dichloromethane), A-2: 24000 (dichloromethane), A- 3: 7100 (dichloromethane), A-7: 7400 (dichloromethane), A-9: 8500 (dichloromethane), A-12: 11400 (dichloromethane), A-17: 9600 (dichloromethane).

Synthesis Example 4 Preparation of Comparative Compound C-3 (Synthesis of Intermediate 1)
200 parts by mass of diacetylcellulose (acetyl substitution degree 2.16) was dissolved in 1500 parts by mass of tetrahydrofuran. To this, 316 parts by mass of pyridine and 927 parts by mass of triphenylmethyl chloride were added and stirred at 70 ° C. for 11 hours. After adding 300 parts by mass of methanol and confirming that the exotherm had subsided, the polymer (intermediate 1) was precipitated by mixing with 7000 parts by mass of methanol and purified by continuous washing with methanol at 40-50 ° C.
After filtration, vacuum drying was performed to obtain 236 parts by mass of Intermediate 1. As a result of NMR measurement, the residual hydroxyl group at the 6-position of diacetylcellulose was almost completely substituted with a triphenylmethyl group.
(Synthesis of Intermediate 2)
50 parts by mass of Intermediate 1 was dissolved in 500 parts by mass of pyridine, and further 64 parts by mass of 4-methoxycinnamic acid chloride was added. After reacting at 70 ° C. for 7 hours, 100 parts by mass of methanol was gradually added, and further mixed with methanol to precipitate Intermediate 2. The product was purified by continuous washing with methanol at 40 to 50 ° C. and then vacuum-dried to obtain 57 parts by mass of Intermediate 2.
(Synthesis of Comparative Compound C-3)
Intermediate 2 was dissolved in 57 parts by mass and 500 parts by mass of dichloromethane, and 21 parts by mass of a 25% hydrobromic acid / acetic acid solution was added. After stirring at room temperature for 5 minutes, 7 parts by mass of triethylamine dissolved in 50 parts by mass of methanol was added and further stirred for 20 minutes. C-3 was reprecipitated by mixing with methanol and purified by continuous washing with methanol at 40 to 50 ° C.
After filtration, it was vacuum-dried to obtain 42 parts by mass of Comparative Compound C-3. Results of NMR measurement, the degree of acetyl substitution ^{(DS 2 = 0.77, DS 3} = 0.78, DS 6 = 0.66), 4- methoxy cinnamoyl degree of substitution ^{(DS 2 = 0.17, DS 3} = 0 .18, DS ⁶ = 0.00). The absorption maximum wavelength of the acetyl group was 220 nm or less, and the absorption maximum wavelength of the 4-methoxycinnamoyl group was 310 nm.

Synthesis Example 5 Preparation of Comparative Compound C-4 Comparative Compound C-4 was synthesized in the same manner as Comparative Compound C-3. Results of NMR measurement, the degree of acetyl substitution ^{(DS 2 = 0.77, DS 3} = 0.78, DS 6 = 0.66), 4- phenylbenzoyl degree of substitution ^{(DS 2 = 0.20, DS 3} = 0. 19, DS ⁶ = 0.00). The absorption maximum wavelength of the acetyl group was 220 nm or less, and the absorption maximum wavelength of the 4-phenylbenzoyl group was 282 nm or less.

Example 1
<Preparation of cellulose compound solution>
The following raw materials were put into a mixing tank, stirred and heated to dissolve, and a cellulose compound solution having the following composition was prepared.
As comparative compounds, C-1: cellulose acetate (Daicel Chemical Industries, Ltd., acetyl substitution degree 2.79), C-2: cellulose acetate butyrate (Eastman Chemical Co., product code 381-20) It was used. The degree of acetyl substitution in Comparative Compound C-1 is DS ² = 0.96, DS ³ = 0.93, DS ⁶ = 0.90. Further, in the comparative compound C-2, the degree of acetyl substitution was DS ² = 0.32, DS ³ = 0.36, DS ⁶ = 0.36, and the degree of butyryl substitution was DS ² = 0.49, DS ³ = 0.59, DS ⁶ = 0.58. The absorption maximum wavelength of the acetyl group is 220 nm or less, and the absorption maximum wavelength of the butyryl group is 220 nm or less.

Cellulose compound solution composition Cellulose compound (type shown in Table 1) 100 parts by mass Methylene chloride (first solvent) 828 parts by mass Methanol (second solvent) 72 parts by mass TPP (plasticizer) 8 parts by mass BDP (plasticizer) 4 parts by mass Part

<Preparation of cellulose film sample>
The cellulose compound solution was cast using a band casting machine. A film having a residual solvent amount of 15% by mass was horizontally stretched at a stretch ratio of 15% using a tenter under the condition of 160 ° C. to produce a film sample (thickness: 92 μm).

<Evaluation>
A part (120 mm × 120 mm) of each film sample obtained above was taken out and evaluated. About retardation, the value of 550 nm was shown. The film was conditioned at 25 ° C. and 10% RH and 25 ° C. and 80% RH for 2 hours, and then the retardation was measured in each environment. The letter of the cellulose film from 10% RH to 80% RH at this time was measured. The amount of change in the foundation was indicated by ΔRe and ΔRth. The results are shown in Table 1.

  As is clear from the results in Table 1, the film prepared from the cellulose compound represented by the general formula (I) is excellent in retardation development and exhibits excellent properties with little variation in Re and Rth due to changes in humidity. I understood it. On the other hand, Comparative Examples C-1 and C-2, in which the type of substituent is outside the scope of the present invention, have low retardation and high humidity dependency. In addition, C-3 having a substitution position distribution different from A-2 and C-4 different from A-1 express large negative Re and Rth, which is not preferable for the purpose of the present invention.

Example 2
Using the sample of Example 1, elliptically polarizing plate samples 002 to 008 were prepared and evaluated by the method described in Example 1 of JP-A-11-316378. The optical properties of the elliptically polarizing plate obtained from the cellulose film of the present invention were excellent. Further, regarding the sample of the present invention, durability over time was not particularly problematic as compared with the protective film of the comparative example.

Example 3
Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the above-described saponified stretched cellulose acylate film of the present invention was used, which was disclosed in JP-A-2002-62431. The bend-aligned liquid crystal cell described in Example 9 of the publication was attached at 25 ° C. and 60% relative humidity, and was brought into 25 ° C. and 10% relative humidity. When the cellulose acylate film of the present invention was used, good display performance with little leakage and little change in contrast was obtained.
Furthermore, it replaced with the cellulose acetate film which apply | coated the liquid crystal layer of Example 1 of Unexamined-Japanese-Patent No. 7-333433, and changed to the stretched cellulose acylate film of this invention, and produced the optical compensation filter film. In this case as well, a good optical compensation film could be produced.
Further, a polarizing plate and a retardation polarizing plate using the cellulose acylate film of the present invention are the liquid crystal display device described in Example 1 of JP-A No. 10-48420 and Example 1 of JP-A No. 9-26572. An optically anisotropic layer containing the discotic liquid crystal molecules described in 1., an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and JP-A-2000 When used in the 20-inch OCB type liquid crystal display device described in FIGS. 10 to 15 of JP-A-154261 and the IPS type liquid crystal display device shown in FIG. A liquid crystal display device was obtained. On the other hand, in the liquid crystal display device produced using cellulose acylate C-1 outside the present invention, light leakage was observed when black display was performed in the dark.

Example 4
According to Example 47 of Invention Association Public Technical Report (Public Technical No. 2001-1745, published on March 15, 2001, Invention Association), a low reflection film was produced using the stretched cellulose acylate film described above. The one using the cellulose acylate film obtained good optical performance.
Further, the low reflection film is formed by using a liquid crystal display device described in Example 1 of JP-A-10-48420, a 20-inch VA liquid crystal display device described in FIGS. 20-inch OCB type liquid crystal display device described in FIGS. 10-15 of 2000-154261, and IPS type liquid crystal display device shown in FIG. 11 of Japanese Patent Application Laid-Open No. 2004-12731. As a result, a good liquid crystal display device with extremely little leakage was obtained.

Claims (13)

A cellulose film comprising a cellulose compound represented by the following general formula (I).

[Wherein, R ¹⁶ , R ¹³ and R ¹² each independently represent a hydrogen atom or a group containing an aliphatic group or an aromatic group. -X ^16- , -X ¹³ -and -X ¹² -are each independently * ¹ -O-, * ¹ -OOC- and * ¹ -OOCNH- (* ¹ is a bond on the six-membered ring side of the cellulose skeleton) Represents). n ¹ represents the average degree of polymerization, represents an integer of 10 to 1500. In addition, R ¹⁶ , R ¹³ , R ¹² , —X ¹⁶ —, —X ¹³ —, and —X ¹² — present in n ¹ each in the cellulose compound may be the same or different for each structural unit. Furthermore, the following relational expressions (Formula I) and (Formula II) are satisfied.
(Formula I)
DS ¹⁶ _long ≧ DS ¹³ _long + DS ¹² _long
(Formula II)
2.5 ≧ DS ¹² _long + DS ¹³ _long + DS ¹⁶ _long > 0.01
Here, DS ¹⁶ _long , DS ¹³ _long and DS ¹² _long are respectively replaced with -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ^{12 in} the 6th, 3rd and 2nd positions. This represents the degree of substitution at the 6-position, 3-position and 2-position of the substituent having the longest absorption among the 3n ¹ substituents. The substituent having the absorption at the longest wave here is -X ¹⁶ -R ¹⁶ , -X ¹³ -R ¹³ and -X ¹² -R ¹² are CH ₃ -X ¹⁶ -R ¹⁶ , CH ₃ -X ^13. In the case of —R ¹³ and CH ₃ —X ¹² —R ¹² , the maximum absorption wavelength at 270 to 450 nm in the solution is the longest wave, and the molar extinction coefficient thereof is 2000 to 1000000. ] The cellulose film according to claim ¹ , wherein the substituent having the longest wave absorption among 3n ¹ substituents is a group containing an aromatic group. The cellulose film according to claim 1 or 2, wherein the substituent having the longest absorption among the 3n ¹ substituents is a group containing at least two aromatic rings. -X ¹⁶ -, - X ¹³ - and -X ¹² - at least one of * ¹ -OOC of - (* ¹ represents a bonding side of the six-membered ring of the cellulose backbone.) Claim 1, which is a The cellulose film of any one of -3. 5. The group according to claim 1, wherein at least one of the 3n ¹ groups represented by R ¹⁶ , R ¹³ and R ¹² is a group not containing an aromatic group. Cellulose film. -X ¹⁶ -R ^16, claim at least one of the 3n substituents represented by -X ¹³ -R ¹³ and -X ¹² -R ^12, characterized in that the acetyl, propionyl or butyryl The cellulose film of any one of 1-5.   A cellulose film obtained by stretching the cellulose film according to any one of claims 1 to 6 by 0.1% to 500% in at least one direction. The in-plane retardation (Re) satisfies the following formula (5), and the thickness direction retardation (Rth) satisfies the following formula (6). 2. The cellulose film according to item 1.
Formula (i): 0 nm ≦ Re ≦ 700 nm
Formula (ii): 0 nm ≦ Rth ≦ 2000 nm   A retardation film using the cellulose film according to claim 1.   It is a polarizing plate which consists of a polarizing film and two protective films which pinch | interpose this polarizing film, Comprising: At least one of two protective films is a cellulose film or the claim of any one of Claims 1-8. Item 10. A polarizing plate, which is the retardation film according to item 9.   An optical compensation comprising an optically anisotropic layer formed by aligning a liquid crystalline compound on the cellulose film according to any one of claims 1 to 8 or the retardation film according to claim 9. the film.   An antireflection film comprising an antireflection layer on the cellulose film according to any one of claims 1 to 8 or the retardation film according to claim 9.   The cellulose film according to claim 1, the retardation film according to claim 9, the polarizing plate according to claim 10, the optical compensation film according to claim 11, and the claim 12. An image display device comprising at least one selected from the group consisting of antireflection films.