JP2008075015A - Cellulose compound, polymer composition, optical film, retardation plate, and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new cellulose compound producing a retardation plate having inverse wavelength dispersion property by a simple production process. <P>SOLUTION: The new cellulose compound is represented by the general formula (1) [wherein, n is an integer of 10-1,500; X<SP>2</SP>, X<SP>3</SP>and X<SP>6</SP>are each -O-, -OCO- or -OCONH-; and at least one of R<SP>2</SP>, R<SP>3</SP>and R<SP>6</SP>is a substituent represented by the general formula (2) (wherein, L is a single bond or alkylene group; V is C, CH or N; and P and Q are each a residue forming an aromatic group-bearing cyclic structure α, wherein on a plane formed by the three atoms, i.e. V<SP>*</SP>(the carbon atom or nitrogen atom as V), P<SP>*</SP>and Q<SP>*</SP>each bound to V<SP>*</SP>, with X-axis in parallel to P<SP>*</SP>-Q<SP>*</SP>and Y-axis as orthogonal to X-axis on the plane, the magnitude of the transition moment of the absorption of the cyclic structure α becomes larger in the order of the X-axis direction and Y-axis direction)]. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cellulose compound, a polymer composition, an optical film, a retardation plate, and a polarizing plate. Specifically, the present invention relates to a retardation plate suitable for a polarizing plate used in a liquid crystal display device, an optical film suitable for the retardation plate, a polymer composition suitable for the optical film, and a cellulose compound contained in the polymer composition. .

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 elements 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 draw ratio, and therefore has a limited range of retardation.

  As means for solving these problems, optical films using fatty acid cellulose ester cellulose mixed acylates such as cellulose acetate propionate and cellulose acetate butyrate have been proposed (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 a range of 60 to 300 nm. 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 (Patent Document 3). However, sufficient knowledge about optical characteristics such as retardation has not been obtained.
JP 2001-188128 A JP 2005-352620 A JP 2002-179701 A

  In view of the above problems, an object of the present invention is to provide a novel cellulose compound, thereby providing a retardation plate having reverse wavelength dispersion such as a broadband λ / 4 plate that can be produced by a simple manufacturing process. There is. Moreover, it is providing the polarizing plate using this phase difference plate.

  As a result of earnest research to solve the above-mentioned problems, a specific material is stretched to form a film or added to a specific film and stretched to reverse wavelength dispersion in the specific film. Has been found to be possible, and the present invention has been completed.

The object of the present invention has been achieved by the following means.
(1) A cellulose compound represented by the following general formula (1).

In general formula (1), n represents an average degree of polymerization and is an integer of 10 to 1500. X ² , X ³ and X ⁶ are each independently a linking group of * —O—, * —OC (═O) — or * —OC (═O) NH— (* represents a bond on the main chain side). Represents. R ² , R ³ , and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituent represented by the following general formula (2). n —X ² —R ² , —X ³ —R ^3, or —X ⁶ —R ⁶ may be different for each structural unit, and n presents R ² , R ³ , and R ^6. Among these, at least one is a substituent represented by the following general formula (2).

(In General Formula (2), L represents a single bond or an alkylene group having 1 to 20 carbon atoms, and —CH ₂ — constituting the alkylene group represents —O—, —S—, —NR— (R represents hydrogen V represents C, CH, or N, P and Q are residues that form a ring structure α having an aromatic group, and have a substituent. may. a carbon atom or a nitrogen atom in this case V and ^{V *, P} * the atom bonded to the ^{V *} in P and Q, respectively, when the ^{Q *,} V * ^-P * -Q ^* of On the plane formed by three atoms, if the direction parallel to P ^* -Q ^* is the X axis and the direction perpendicular to the X axis on the plane is the Y axis, the magnitude of the transition moment of absorption of the ring structure α Is larger in the order of the X-axis direction and the Y-axis direction, provided that the transition moment is (This is a value obtained by calculating the transition moment of absorption of the compound represented by formula (3).)

(In general formula (3), V, P, Q and ring structure α have the same meanings as in general formula (2).)
(2) Substituents represented by -X ² -R ² , -X ³ -R ³ , and -X ⁶ -R ⁶ , wherein R ² , R ³ , and R ⁶ are represented by the general formula ( The cellulose compound according to (1), wherein the average degree of substitution (B) of the substituent represented by 2) satisfies the following formula (I).
Formula (I) 0.1 <(B) <2.5
However, the ^-X 2 ^-R 2 in cellulose compound, ^-X 3 -R ^3, and the average degree of substitution sum of the substituents represented by ^{-X 6 -R 6 (-X 2 -R} 2) + (- ^{X 3 -R 3) + (-} X 6 -R 6) is 3.0.
(3) the ^-X 2 ^-R 2, a substituent represented by ^-X 3 -R ^3, and ^-X 6 -R ^6, wherein ^R 2, ^{R 3,} and ^{R 6} is 1 to carbon atoms The average degree of substitution (A) of the substituent that is an alkyl group of 10 and the average degree of substitution (B) of the substituent in which R ² , R ³ , and R ⁶ are represented by the general formula (2) are as follows: The cellulose compound according to item (2), which satisfies formulas (I) to (III).
Formula (I) 0.1 <(B) <2.5
Formula (II) 0.5 <(A) <2.9
Formula (III) 0.6 <(A) + (B) <3.0
However, the ^-X 2 ^-R 2 in cellulose compound, ^-X 3 -R ^3, and the average degree of substitution sum of the substituents represented by ^{-X 6 -R 6 (-X 2 -R} 2) + (- ^{X 3 -R 3) + (-} X 6 -R 6) is 3.0.
(4) The ring structure α is a structure containing at least one selected from the group consisting of a nitrogen-containing five-membered ring, a nitrogen-containing six-membered ring, an aromatic hydrocarbon, and an alicyclic hydrocarbon. The cellulose compound according to any one of (3).
(5) X < ¹ >, X < ² > and X < ³ > are any one of (1) to (4), wherein * -OC (= O)-(* represents a bond on the pyranose ring side). Cellulose compound.
(6) A polymer composition comprising at least one cellulose compound according to any one of (1) to (5).
(7) An optical film formed from the polymer composition described in (6).
(8) A retardation film comprising the optical film according to item (7).
(9) The polymer composition according to (6), comprising at least one polymer composition, subjected to an orientation treatment such as stretching, wherein the birefringence Δn (550 nm) is positive with respect to the orientation direction and has a specific wavelength A retardation film comprising a film having a birefringence Δn satisfying the following mathematical formulas (V) and (VI):
Formula (V) 0.5 <Δn (450 nm) / Δn (550 nm) <1.0
Formula (VI) 1.05 <Δn (630 nm) / Δn (550 nm) <1.5
(10) A polarizing plate, wherein the retardation plate according to (8) or (9) is disposed on at least one side of a polarizer.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Cellulose compound]
In the present invention, the cellulose compound includes a cellulose compound and a compound having a cellulose skeleton obtained by introducing a functional group biologically or chemically using cellulose as a raw material.
The cellulose compound of the present invention is represented by the general formula (1).

  In general formula (1), n represents an average degree of polymerization, and is an integer of 10 to 1500. Depending on the structure of the repeating unit and the use of the compound, 50 to 1000 is preferable. More preferably, it is the range of 100-500.

In general formula (1), X ¹ , X ² , and X ³ are each independently * —O—, * —OC (═O) — or * —OC (═O) NH— (* is the main chain side) ) Represents a linking group, and * -O- and * -OC (= O)-are preferable, and * -OC (= O)-is more preferable. In addition, X ² , X ^3, and X ⁶ that are present n times in the cellulose body may be the same or different for each structural unit.

In General Formula (1), R ² , R ³ , and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituent represented by General Formula (2) below. And at least one of R ² , R ³ , and R ⁶ each present n is a substituent represented by the general formula (2). As a C1-C10 alkyl group, it may have a branch and may form a ring. Further, the alkyl group may have a substituent, but is preferably a linear alkyl group having 1 to 8 carbon atoms, more preferably a linear alkyl group having 1 to 5 carbon atoms, still more preferably a methyl group, An ethyl group and an n-propyl group.

  Next, the substituent represented by the general formula (2) will be described.

In the formula, L represents a single bond or an alkylene group having 1 to 20 carbon atoms, may be linear or branched, and may have a ring structure. Preferably it is a C1-C15 alkylene group, More preferably, it is C1-C10, More preferably, it is a C1-C5 alkylene group. Specific ring structures include a cyclohexylene group and a bicyclohexylene group. Further, —CH ₂ — in L may be substituted with —O—, —S—, —NR— (R is a hydrogen atom or a substituent). For _{example, -OCH 2 -, - OCH 2} CH 2 -, - CH 2 OCH 2 -, - OCH 2 CH 2 CH 2 - and the like.

V represents C, CH, or N, and P and Q are residues that form a ring structure α having an aromatic group, and may have a substituent. In this case, a carbon atom or a nitrogen atom in V and ^{V *,} the atom bonded to the ^{V *} in P and Q, respectively ^P *, when the ^{Q *,} the V * ^-P * -Q ^* of 3 atoms On the plane to be formed, if the direction parallel to P ^* -Q ^* is the X axis, and the direction perpendicular to the X axis on the plane is the Y axis, the magnitude of the transition moment of absorption of the ring structure α is the X axis. (The transition moment of absorption is the amount of change in the electric dipole moment at the time of transition, and is given by calculating the wave function of the state before and after the transition.) The satisfactory ring structure α is not limited and may be monocyclic or polycyclic. It is also preferable to have a condensed ring structure. In particular, the ring structure α preferably contains any of a nitrogen-containing five-membered ring, a nitrogen-containing six-membered ring, an aromatic hydrocarbon, and an alicyclic hydrocarbon.
However, the transition moment is a value obtained by calculating the transition moment of absorption of the compound represented by the following general formula (3).

(In general formula (3), V, P, Q and ring structure α have the same meanings as in general formula (2).)
When the magnitude of the transition moment in the Y-axis direction is smaller than or equal to the magnitude of the transition moment in the X-axis direction, the wavelength dispersion of the stretched film obtained becomes forward dispersion.
Since the transition moment of absorption of the ring structure α of the cellose compound is larger in the order of the X-axis direction and the Y-axis direction, the stretched film containing the compound has an absorption transition wavelength in the MD direction more than that in the TD direction. Long wave can be achieved.

  Hereinafter, the preferred ring structure α of the present invention will be described in detail with specific examples, but the present invention is not limited to the following specific examples.

In addition, about the two glucopyranose rings located in the terminal of the cellulose compound of this invention, it is possible to have a substituent also in the hydroxyl group of 1-position or 4-position, However, The kind of the substituent is not specifically limited. Preferable examples include a hydrogen atom, an alkyl group (preferably having 1 to 24 carbon atoms, more preferably 1 to 18 carbon atoms, still more preferably 1 to 12 carbon atoms), an aliphatic acyl group (preferably having 2 to 24 carbon atoms). More preferably 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, and an aromatic acyl group (preferably 6 to 30 carbon atoms, more preferably 6 to 24 carbon atoms, particularly preferably 6 to 20 carbon atoms). ), and it can include a group represented by the above ^{-X 2 -R 2, -X 3 -R} 3 or ^-X 6 -R ^6.

The β-1,4 bonded glucose units 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.
That is, the sum of the general formula in the compounds represented by ^{(I), -X 2 -R 2} , -X 3 -R 3, and the average degree of substitution of substituents represented by ^-X 6 -R ⁶ of the present invention ^{(-X 2 -R 2) + (} - X 3 -R 3) + (- X 6 -R 6) becomes 3.0.
-X ² -R ^2, a substituent represented by ^-X 3 -R ^3, and ^-X 6 -R ^6, tables in the ^R 2, ^{R 3,} and ^{R 6} is the formula (2) The average degree of substitution (B) of the substituents to be satisfied preferably satisfies the formula (I), and more preferably satisfies the formula (I ′). It is more preferable to satisfy the formula (I ″).
Formula (I) 0.1 <(B) <2.5
Formula (I ′) 0.1 <(B) <2.0
Formula (I ″) 0.15 <(B) <1.5

Further, simultaneously with the formulas (I), (I ′) and (I ″), the substituent is represented by —X ² —R ² , —X ³ —R ³ , —X ⁶ —R ⁶ , The average substitution degree (A) of the substituent in which R ² , R ³ and R ⁶ are alkyl groups having 1 to 10 carbon atoms preferably satisfies the formula (II), and more preferably satisfies the formula (II ′). preferable. It is more preferable to satisfy the formula (II ″).
Formula (II) 0.5 <(A) <2.9
Formula (II ′) 0.8 <(A) <2.5
Formula (II ″) 1.0 <(A) <2.4
Therefore, it is preferable that (A) and (B) satisfy the following formula (III).
Formula (III) 0.6 <(A) + (B) <3.0

In the present invention, the average degree of substitution of substituents can be obtained by identifying the functional groups contained from signal data obtained by ¹ H-NMR or ¹³ C-NMR, and determining the integrated values of signals corresponding to the respective substituents. It can be determined by a conventional method for calculating the degree of substitution from the ratio of the obtained integral values.

<Method for producing cellulose compound>
For general synthesis methods of cellulose compounds, 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, Vol. 2, pages 402-407, “Encyclopedia of Cellulose” pages 131-144, edited by Cellulose Society, 2000, Comprehensive Cellulose Chemistry, Volume 2, Wiley-Vch, 2001, etc. The present invention can also be applied as appropriate.

The method for synthesizing the cellulose compound of the present invention can be selected from one-step or multi-step synthesis.
In the one-step synthesis method, synthesis is carried out by carrying out esterification or etherification from cellulose. When the cellulose compound of the present invention is a mixed ester or a mixed ether, it can be used as an esterifying agent or an etherifying agent. What is necessary is just to make it react using the mixture of more than a kind.
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 can be modified by methods such as etherification and esterification (including carbonate esterification and carbamate esterification). This is particularly useful when synthesizing the compound of the present invention. In industrial methods for producing cellulose derivatives, esterification, hydrolysis, depolymerization, etc. may be carried out sequentially or simultaneously without removing 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.

  In the present invention, the cellulose raw material is preferably subjected to a pretreatment (activation) in which it is brought into contact 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, dropping, and dipping, and the activation may take any temperature and time.

(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 mixture. Filtration may be performed in any step from the reaction to the reprecipitation of the cellulose compound 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)
By mixing the cellulose compound solution thus obtained in a poor solvent (a solvent containing water, alcohol, etc.) or by mixing the poor solvent in the cellulose compound solution, the cellulose derivative 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.

<Degree of polymerization of cellulose acylate>
In the present invention, the cellulose compound is preferably cellulose acylate, and more preferably cellulose acetate. The degree of polymerization of cellulose acylate is preferably 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. By setting the degree of polymerization to 700 or less, the viscosity of the cellulose acylate dope solution does not become too high, and the film production by casting tends to be easy. Moreover, it is preferable that the polymerization degree is 180 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.
Further, the molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a weight average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight distribution is Narrow is preferred. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and further preferably 1.0 to 1.6. preferable.

When the low molecular component is removed, the average molecular weight (degree of polymerization) is increased, but the viscosity is lower than that of ordinary cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of the cellulose acylate used in the present invention, the moisture content of the cellulose acylate is preferably 2% by mass or less, more preferably 1% by mass or less, and 0.7% by mass. More preferably, it is as follows. It is known that normal cellulose acylate contains water at a ratio of 2.5 to 5% by mass. In such a case, it is preferable to dry the cellulose acylate in order to obtain a preferable water content in the present invention. The drying method is not particularly limited as long as it can achieve the desired moisture content.
In addition, as the raw material cotton and the synthesis method of cellulose acylate in the present invention, for example, disclosed in the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, pages 7 to 12, published on March 15, 2001, Invention Association). Those described can be preferably employed.

<Additives to cellulose acylate>
The polymer composition of the present invention is a composition comprising at least one cellulose compound as described above. In the present invention, the polymer composition refers to a composition comprising a cellulose compound defined by the general formula (1) and at least one selected from the following (A) to (D).
(B) Solvent for making a solution (b) Cellulose compounds other than those defined by the general formula (1) (c) Various general additives (d) Additives other than the above Polymer composition of the present invention One of the preferred embodiments is a cellulose acylate solution. At this time, when the polymer composition is a solid, the cellulose compound defined by the general formula (1) is preferably included in an amount of 50% by mass to 100% by mass, and included in an amount of 60-100% by mass. It is more preferable that 70-100 mass% is contained. Moreover, when it is a cellulose acylate solution, it is preferable that the cellulose compound prescribed | regulated by said General formula (1) is contained 1-40 mass%, and it is more contained 3-30 mass%. Preferably, 5 to 25% by mass is contained.
Various additives (for example, an ultraviolet ray preventing agent, a plasticizer, a deterioration preventing agent, fine particles, an optical property adjusting agent, etc.) can be added to the cellulose acylate solution. Further, the additive may be added at any time during the dope preparation process, and these additives may be added as a preparation process at the end of the dope preparation process.

  These additives may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, an ultraviolet absorber at 20 ° C. or lower and an ultraviolet absorber at 20 ° C. or higher can be mixed and used, and similarly, a plasticizer can be mixed and used. Specifically, the method described in JP 2001-151901 A can be employed.

(UV absorber)
As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. Preferred are benzophenone series, benzotriazole series, and salicylic acid ester series.

  Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert- Butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) ) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like.

  Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate.

  Among these exemplified UV absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2- (2′-hydroxy-3′-tert-butyl) -5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert) -Amylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. The ultraviolet absorbent for liquid crystal is preferably one that is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal and that has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly preferred ultraviolet absorbers are the above-described benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

  As for the UV absorber, 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-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 These compounds can also be used.

  0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is 0.001% by mass or more, the effect of addition can be sufficiently exerted, and if the addition amount is 5% by mass or less, it is preferable because bleeding out of the ultraviolet absorber to the film surface can be suppressed.

  Further, the ultraviolet absorber may be added simultaneously with dissolution of cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because spectral absorption characteristics can be easily adjusted.

(Deterioration inhibitor)
The deterioration inhibitor may be added to prevent cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. A compound such as a UV absorber (JP-A-6-118233) can be used.

(Plasticizer)
The plasticizer is preferably a phosphate ester and / or a carboxylic acid ester. As the phosphate ester plasticizer, for example, triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate and the like are preferable. . Examples of the carboxylate plasticizer include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), O -Triethyl acetyl citrate (OACTE), tributyl O-acetyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, triacetin, tributyrin, butyl phthalyl butyl Glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate and the like are preferable. Furthermore, the plasticizer is preferably (di) pentaerythritol esters, glycerol esters, diglycerol esters.

(Peeling accelerator)
Preferred examples of the peeling accelerator include citric acid ethyl esters.
(Infrared absorber)
As the infrared absorber, for example, those described in JP-A No. 2001-194522 are preferable.

(dye)
In the present invention, a dye for adjusting the hue may be added. The content of the dye is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm in terms of a mass ratio with respect to cellulose acylate. By containing the dye in this way, light piping of the cellulose acylate film can be reduced, and yellowness can be improved. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation. Moreover, you may add to the ultraviolet absorber liquid added in-line. The dyes described in JP-A-5-34858 can be used.

(Matting agent fine particles)
The optical film of the present invention is formed of the above-described polymer composition of the present invention. A cellulose acylate film is preferred as the optical film of the present invention.
Fine particles may be added as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate. And calcium phosphate. As the fine particles, those containing silicon are more preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary / secondary particle size, the particles in the film were observed with a scanning electron microscope, and the diameter of the circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

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

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

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a fine particle dispersion. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are stirred and mixed in advance, adding this fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with a main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, after adding a small amount of cellulose ester to the solvent and dissolving with stirring, add fine particles to this and disperse with a disperser. This is used as a fine particle additive solution, and this fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer. There is also a method of mixing. Although the present invention is not limited to these methods, the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. More preferred is mass%. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

(Compound addition ratio)
In the cellulose acylate film of the present invention, the total amount of compounds having a molecular weight of 3000 or less is preferably 5 to 45% by mass with respect to the mass of cellulose acylate. More preferably, it is 10-40 mass%, More preferably, it is 15-30 mass%. As described above, these compounds include compounds that reduce optical anisotropy, wavelength dispersion adjusters, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, and the like. Furthermore, the total amount of compounds having a molecular weight of 2000 or less is more preferably within the above range. By setting the total amount of these compounds to 5% by mass or more, it becomes difficult for the properties of the cellulose acylate alone to be produced. Further, by setting the total amount of these compounds to 45% by mass or less, it exceeds the limit that the compounds are compatible with each other in the cellulose acylate film, and is precipitated on the film surface to suppress the cloudiness of the film (crying out from the film). It tends to be preferable.

<Organic solvent of cellulose acylate solution>
In this invention, it is preferable to manufacture a cellulose acylate film by the solvent cast method, and it is preferable to manufacture using the solution (dope) which melt | dissolved the cellulose acylate in the organic solvent. The organic solvent preferably used as the main solvent in the present invention is preferably a solvent selected from esters, ketones, ethers having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 7 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.

  As described above, for the cellulose acylate film of the present invention, a chlorinated halogenated hydrocarbon may be used as a main solvent. For example, the disclosed technique (published technical report 2001-1745, pages 12-16, issued in 2001, invention. As described in the Association), a non-chlorine solvent may be used as the main solvent.

In addition, as the solvent for the cellulose acylate solution and the film, those disclosed in the following patent documents including the dissolution method can be mentioned as a preferred embodiment. JP 2000-95876 A, JP 12-95877 A, JP 10-324774 A, JP 8-152514 A, JP 10-330538 A, JP 9-95538 A, JP 9-95557 A, Special Kaihei 10-235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10-323853, JP-A-10-323853 JP-A-10-237186, JP-A-11-60807, JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, and JP-A-11-60752.
According to these patent documents, not only the preferable solvent for the cellulose acylate of the present invention but also the solution physical properties and coexisting substances to be coexisted are described, and these are also preferable embodiments in the present invention.

<Manufacturing process of cellulose acylate film>
Next, a method for producing a film using a cellulose acylate solution will be described. As a method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be widely adopted.

(Dissolution process)
The method for dissolving the cellulose acylate solution (dope) is not particularly limited, and it may be performed at room temperature or further by a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose acylate solution in the present invention, and further the steps of solution concentration and filtration accompanying the dissolution step, JIII Journal of Technical Disclosure (Technical No. 2001-1745, pages 22-25, March 15, 2001) The manufacturing process described in detail in the Japanese publication, Invention Association) is preferably used.

  The dope transparency of the cellulose acylate solution in the present invention is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. In the present invention, it was confirmed that various additives were sufficiently dissolved in the cellulose acylate dope solution. As a specific method for calculating the dope transparency, the dope solution is injected into a 1 cm square glass cell, and the absorbance at 550 nm is measured with a spectrophotometer (UV-3150, trade name, Shimadzu Corporation). Only the solvent is measured in advance as a blank, and the transparency of the cellulose acylate solution is calculated from the ratio with the absorbance of the blank.

(Casting, drying, winding process)
The dope (cellulose acylate 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 pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of revolutions, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as web) is peeled from the metal support at the peeling point where the metal support is uniformly cast on the metal support, and the metal support has almost gone around. The both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width and dried, and then the obtained film is mechanically transported by a roll group of a drying device, dried, and then rolled by a winder. Wind up to a predetermined length. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film or the silver halide photographic light-sensitive material which is an optical member for electronic display, which is the main use of the cellulose acylate film of the present invention, the solution casting film forming apparatus In addition, a coating apparatus is often added for surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, and a protective layer. These are described in detail in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, pages 25-30, published on March 15, 2001, Japan Institute of Invention), and include casting (including co-casting). ), Metal support, drying, peeling, etc., and can be preferably used in the present invention.

(Extension process)
The cellulose acylate film preferably used in the present invention preferably has a retardation value adjusted by stretching. In particular, when the in-plane retardation value of the cellulose acylate film is set to a high value, a method of positively stretching in the width direction, for example, JP-A-62-115035, JP-A-4-152125, A method for stretching the produced film described in JP-A-4-284111, JP-A-4-298310, and JP-A-11-48271 can be used.

  The film is stretched at room temperature or under heating conditions. The heating temperature is preferably not higher than the glass transition temperature of the film. The stretching of the film may be uniaxial stretching only in the longitudinal or lateral direction, or may be simultaneous or sequential biaxial stretching. The film is preferably stretched by 1 to 200%, more preferably stretched by 1 to 100%, and further preferably stretched by 1 to 50%.

  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 in-plane slow axis of the cellulose acylate 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, it is composed of the roll film-like polarizing film and the roll film-like cellulose acylate film. In order to continuously bond the protective film, the in-plane slow axis of the roll film-shaped 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 acylate 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 30 μm. More preferably, it is in the range of 150 μm. 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 acylate 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 knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm 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 variation in the Re (590) value in the width direction of the film is preferably ± 5 nm, and 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.

<Optical properties of cellulose acylate film>
(Measurement of Re and Rth)
In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the 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” (trade name, manufactured by Oji Scientific Instruments). Rth (λ) is from the direction inclined by + 40 ° with respect to the film normal direction, with Re (λ) and the in-plane slow axis (determined by “KOBRA 21ADH”) as the tilt axis (rotation axis). With the retardation value measured by the incidence of light of wavelength λnm and the slow axis in the plane as the tilt axis (rotation axis), the light of wavelength λnm is incident from a direction inclined by -40 ° with respect to the film normal direction. The KOBRA 21ADH is calculated based on the retardation values measured in the three directions in total, the assumed value of the average refractive index, and the input film thickness value.
Here, as the assumed value of the average refractive index, “Polymer Handbook” (JOHN WILEY & SONS, INC) and catalog values of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

Re (λ) value and Rth (λ) value satisfy the following formulas (7) and (8), respectively, in order to widen the viewing angle of a liquid crystal display device, particularly a VA mode and OCB mode liquid crystal display device. Is preferred. In particular, a film (preferably a cellulose acylate film) is preferable when used as a protective film on the liquid crystal cell side of the polarizing plate.
Formula (7): 0 nm ≦ Re (590) ≦ 200 nm
Formula (8): 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, the following expressions (7-1) and (8-1) are satisfied.
Formula (7-1): 30 nm ≦ Re (590) ≦ 150 nm
Formula (8-1): 30 nm ≦ Rth (590) ≦ 300 nm

When a film (preferably a cellulose acylate film) preferably used in the present invention is used for the VA mode and the OCB mode, a mode in which two sheets are used on both sides of the cell in total (two-sheet type), and the top and bottom of the cell There are two types of forms (single sheet type) that are used only on either side.
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.

<Water permeability of film>
The moisture permeability of the optical film of the present invention (preferably a cellulose acylate film) is measured under the conditions of a temperature of 60 ° C. and a humidity of 95% RH (relative humidity) based on JIS standard JIS Z 0208. It is preferably 400 to 2000 g / m ² · 24 h in terms of conversion. More preferably 500~1800g / m ² · 24h, and particularly preferably 600~1600g / m ² · 24h. By setting it to 2000 g / m ² · 24 h or less, the absolute value of the humidity dependence of the Re value and Rth value of the film hardly exceeds 0.5 nm /% RH, which is preferable. Also, when an optically anisotropic film is formed by laminating an optically anisotropic layer on the film of the present invention (preferably a cellulose acylate film), the absolute value of humidity dependency of Re value and Rth value is 0.5 nm /%. It is difficult to exceed RH, which is preferable. When this optical compensation sheet or polarizing plate is incorporated in a liquid crystal display device, it causes a change in color and a decrease in viewing angle. In addition, when the moisture permeability of the film (preferably cellulose acylate film) is set to 400 g / m ² · 24 h or more, the film (preferably cellulose acylate film) is used when a polarizing plate is produced by sticking to both surfaces of the polarizing film. The rate film) makes it difficult for the adhesive to dry and poor adhesion.
If the film (preferably cellulose acylate film) is thick, the moisture permeability tends to be small, and if the film is thin, the moisture permeability tends to be large. Therefore, the moisture permeability in the present invention is described as a value obtained by converting the film thickness to 80 μm. Conversion of the film thickness is obtained as (water vapor permeability in terms of 80 μm = measured water vapor permeability × measured film thickness μm / 80 μm).
The measurement method for moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285 to 294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The film (preferably cellulose acylate film) sample 70 mmφ of the present invention is conditioned at 25 ° C. 90% RH and 60 ° C. 95% RH for 24 hours, respectively, and a moisture permeation test apparatus (KK-709007, trade name, Toyo Seiki Co., Ltd.) calculates the amount of water per unit area according to JIS Z-0208 (g / m ² ), and moisture permeability = mass after moisture conditioning−before moisture conditioning Calculate by mass.

<Residual solvent amount of film>
In this invention, it is preferable to dry on the conditions from which the amount of residual solvents with respect to a film (preferably cellulose acylate film) becomes the range of 0.01-1.5 mass%. More preferably, it is 0.01-1.0 mass%. When the film of the present invention (preferably a cellulose acylate film) is used as a support, curling can be further suppressed by setting the amount of residual solvent within this range. This is presumably because the main effect factor is that the free volume is reduced by reducing the amount of residual solvent at the time of film formation by the solvent casting method described above.

<Hygroscopic expansion coefficient of film>
The hygroscopic expansion coefficient of the film of the present invention (preferably a cellulose acylate film) is preferably 30 × 10 ⁻⁵ /% RH or less, more preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 ×. More preferably, it is 10 ⁻⁵ /% RH or less. The lower limit is not particularly defined, and the hygroscopic expansion coefficient tends to be preferably small, but more preferably 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. By adjusting the hygroscopic expansion coefficient, when the film of the present invention (preferably a cellulose acylate film) is used as an optical compensation film support, the frame-shaped transmittance is maintained while maintaining the optical compensation function of the optical compensation film. Light leakage due to the rise, that is, distortion can be prevented.

<Surface treatment>
The film (preferably cellulose acylate film) is optionally surface-treated to achieve improved adhesion between the film (preferably cellulose acylate film) and each functional layer (for example, the undercoat layer and the back layer). can do. 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 (0.133 Pa to 2.67 kPa), and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and 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 the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, pages 30 to 32, issued on March 15, 2001, Invention Association), and preferably used in the present invention. Can do.

(Alkaline saponification treatment)
The alkali saponification treatment is preferably carried out by a method in which a film (preferably a cellulose acylate film) is directly immersed in a tank of a saponification solution or a method in which a saponification solution is applied to a film (preferably a cellulose acylate film). Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkaline saponification treatment coating solution has good wettability in order to apply the saponification solution to the film (preferably a cellulose acylate film), and the saponification solution solvent causes the film (preferably the cellulose acylate film) to be coated on the surface. It is preferable to select a solvent that keeps the surface shape good without forming irregularities. 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 alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water.

<Functional layer>
The film of the present invention is applied to optical applications and photographic light-sensitive materials. In particular, the optical application is preferably a liquid crystal display device, and the liquid crystal display device has a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizing elements disposed on both sides thereof, and the liquid crystal It is more preferable that at least one optical compensation sheet is disposed between the cell and the polarizing element. These liquid crystal display devices include TN (Twisted Nematic), IPS (In-Plane Switching Crystal), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCB (Optic LiquidTypical Crystal). ), ECB (Electrically Controlled Birefringence), VA (Vertically Aligned) and HAN (Hybrid Aligned Nematic).
In that case, when using the film of this invention for the above-mentioned optical use, providing various functional layers is implemented. These are, for example, an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. These functional layers and materials for which the film of the present invention can be used include surfactants, slip agents, matting agents, antistatic layers, hard coat layers and the like. 2001-1745, pages 32 to 45, published on March 15, 2001, Invention Association), and can be preferably used in the present invention.

In the present invention, in a film containing at least one cellulose compound represented by the above general formula (I) and subjected to orientation treatment such as stretching of the polymer composition, birefringence Δn (550 nm) with respect to the orientation direction. Is positive and the birefringence Δn at a specific wavelength is expressed by the formula (V) 0.5 <Δn (450 nm) / Δn (550 nm) <1.0
Formula (VI) 1.05 <Δn (630 nm) / Δn (550 nm) <1.5
It is preferable that
In order to exhibit such wavelength dispersion of Δn, the absorption wavelength and the transition moment direction in the orientation direction (hereinafter referred to as TD direction) and the direction orthogonal to the direction (hereinafter referred to as MD direction) are arranged well. There is a need.

Since Δn is a value obtained by subtracting the refractive index in the MD direction from the refractive index in the TD direction, the wavelength dispersion in the MD direction is more downward than the wavelength dispersion of the refractive index in the TD direction. Formula (V) and (VI) are satisfied if the side and the left are slopes of Δn when the left side is the short wavelength side. Since the wavelength dispersion of the refractive index is closely related to the absorption of the substance as represented by the Lorentz-Lorenz equation, in order to make the wavelength dispersion in the MD direction more downward, TD It is only necessary to make the absorption transition wavelength in the MD direction longer than that in the direction.
By using the cellulose compound represented by the general formula (1) of the present invention, an optical transition film that can make the absorption transition wavelength in the MD direction longer than the TD direction and satisfies the formulas (V) and (VI) It can be.

[Polarizer]
The use of the optical film of the present invention will be described.
The optical film of the present invention is particularly useful for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. There is a method in which the obtained film is treated with an alkali and bonded to both surfaces of a polarizing film prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.
Examples of the adhesive used to bond the protective film treated surface and the polarizing film include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.
The polarizing plate is composed of a polarizing film and protective films that protect both surfaces thereof, and may further be configured by bonding a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.
In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, an excellent display property can be obtained regardless of the location of the polarizing plate protective film to which the film of the present invention is applied. In particular, the polarizing plate protective film on the display side outermost surface of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like.

[Phase difference plate (optical compensation film)]
The optical film of the present invention can be used in various applications, and is particularly effective when used as a retardation plate of a liquid crystal display device. The retardation film is generally used for a liquid crystal display device and refers to an optical material that compensates for a retardation, and is synonymous with an optical compensation film, an optical compensation sheet, and the like. The retardation plate has birefringence and is used for the purpose of removing the coloring of the display screen of the liquid crystal display device or improving the viewing angle characteristics.

[Liquid Crystal Display]
<Configuration of general liquid crystal display device>
When the film of the present invention is used as an optical compensation film, the transmission axis of the polarizing film and the slow axis of the optical compensation film made of the film of the present invention may be arranged at any angle. The liquid crystal display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing films disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing film. The optical compensation film is arranged.
The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell preferably has a thickness of 50 μm to 2 mm.

<Types of liquid crystal display devices>
The film of the present invention can be used for liquid crystal cells in various display modes. Specifically, display modes such as TN, IPS, FLC, AFLC, OCB, STN, VA, ECB, and HAN are listed. The display mode can also be used in a display mode in which the orientation is divided. Further, the film of the present invention can be preferably used in any of transmissive, reflective, and transflective liquid crystal display devices.

(TN type liquid crystal display device)
The 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. Also, Mori et al. (Jpn. J. Appl. Phys. Vol. 36, (1997), p. 143 and Jpn. J. Appl. Phys. Vol. 36, (1997), p. 1068). ).

(STN type liquid crystal display device)
You may use the film of this invention as a support body of the optical compensation sheet | seat of the STN type liquid crystal display device which has a liquid crystal cell of STN mode. 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 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 and ECB liquid crystal display device)
The film of the present invention is also advantageously used as a support for an optical compensation sheet of an IPS liquid crystal display device and an ECB liquid crystal display device having IPS mode and ECB mode liquid crystal cells, or as 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 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 aspect, the polarizing plate using the 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 among the protective films of the polarizing plate above and below the liquid crystal cell. Is preferably used 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 and HAN type liquid crystal display device)
The 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 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 Japanese Patent 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 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 an 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, (1998), p. 1089).

<Hard coat film, antiglare film, antireflection film>
The film of the present invention can also be preferably used for a hard coat film, an antiglare film and an antireflection film. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., any or all of a hard coat layer, an antiglare layer and an antireflection layer are imparted to one or both sides of the film of the present invention. Can do. A preferred embodiment of such an antiglare film or antireflection film is described in detail in JIII Journal of Technical Disclosure (Technology No. 2001-1745, pages 54 to 57, issued on March 15, 2001, Invention Association). The film of the present invention can be preferably used.

<Photographic film support>
Furthermore, the film of the present invention can also be applied as a support for silver halide photographic light-sensitive materials. Specifically, the film of the present invention is preferably used according to the description regarding color negative in JP-A-2000-105445. Further, application as a support for a color reversal silver halide photographic light-sensitive material is also preferable, and it can be produced according to various materials, formulations and processing methods described in JP-A No. 11-282119.

<Transparent substrate>
The film of the present invention has optical anisotropy close to zero and can have excellent transparency. Therefore, the film of the present invention can be used as an alternative to the liquid crystal cell glass substrate of a liquid crystal display device, that is, as a transparent substrate for encapsulating driving liquid crystal. be able to.
Since the transparent substrate enclosing the liquid crystal needs to have excellent gas barrier properties, a gas barrier layer may be provided on the surface of the film of the present invention as necessary. The form and material of the gas barrier layer are not particularly limited, but SiO ₂ or the like is vapor-deposited on at least one side of the film of the present invention, or a polymer coating having a relatively high gas barrier property such as a vinylidene chloride polymer or a vinyl alcohol polymer. A method of providing a layer is conceivable, and these can be used as appropriate.
In order to use as a transparent substrate for enclosing liquid crystal, a transparent electrode for driving the liquid crystal by applying a voltage may be provided. Although it does not specifically limit as a transparent electrode, A transparent electrode can be provided by laminating | stacking a metal film, a metal oxide film, etc. on the at least single side | surface of the film of this invention. Among these, a metal oxide film is preferable from the viewpoint of transparency, conductivity, and mechanical properties, and an indium oxide thin film containing mainly 2 to 15% by mass of tin oxide and zinc oxide can be preferably used. For details of these techniques, for example, methods described in JP-A Nos. 2001-125079 and 2000-227603 can be used.

  In order to control the Re value and the Rth value of the film of the present invention (preferably a cellulose film) within a preferable range, the type and addition of the cellulose compound (retardation control agent) represented by the general formula (I) to be used It is preferable to appropriately adjust the amount and the stretching ratio of the film. In particular, in the present invention, by appropriately setting the addition amount of the retardation control agent and the stretching ratio of the film so that a desired Re value can be obtained from the cellulose compound represented by the general formula (I), A film having a desired Re value can be obtained.

  Hereinafter, the present invention will be described in more detail based on 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 following examples.

[Example 1: Synthesis of cellulose compound]
<Synthesis Example 1-1: Synthesis of Compound (a)>
Compound (a) was synthesized according to the following scheme.

(Synthesis of Synthesis Intermediate (a-1))
Carbazole 75 parts by mass, potassium carbonate 90 parts by mass, and 1-methyl-2-pyrrolidone 750 parts by mass were weighed into a 2 l three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, and stirred at room temperature. 84 mass parts of methyl 3-bromopropionate was dripped here, keeping room temperature. After completion of dropping, the temperature was raised to 110 ° C. and stirred for 5 hours. Thereafter, the mixture was allowed to cool to near room temperature, and the reaction solution obtained by filtering out potassium carbonate was extracted with ethyl acetate and 0.5N hydrochloric acid. Subsequently, recrystallization from methanol was performed to obtain 65 parts by mass of the target (a-1).

(Synthesis of Synthesis Intermediate (a-2))
50 parts by mass of (a-1) was weighed into a 1 l three-necked flask equipped with a mechanical stirrer, thermometer, condenser, and dropping funnel, and dissolved in 400 parts by mass of methanol. 120 mass parts of 2N sodium hydroxide aqueous solution was added here, and it stirred at 65 degreeC for 2 hours. 1N hydrochloric acid was added in an ice bath so that the pH of the reaction solution was 1, and this was extracted and washed with ethyl acetate. After drying over sodium sulfate, ethyl acetate was distilled off under reduced pressure to obtain 45 parts by mass of the desired (a-2).

(Synthesis of Compound (a))
In a 500 ml three-necked flask, 40 parts by mass of compound (a-2) was weighed and dissolved in 200 parts by mass of toluene. 40 mass parts of thionyl chloride was added here, and it stirred at 60 degreeC. After confirming the formation of the target compound (a) by TLC, the solvent and thionyl chloride were distilled off under reduced pressure to obtain 38 parts by mass of the target (a).

<Synthesis Example 1-2: Synthesis of Compound (b)>

  In the synthesis of the compound (a), the reaction was carried out in the same manner except that the starting carbazole was changed to indole to obtain the compound (b).

<Synthesis Example 1-3 (Comparative Example): Synthesis of Comparative Compound (d)>

  In a 500 ml three-necked flask, 40 parts by mass of 4-biphenylacetic acid was weighed and dissolved in 200 parts by mass of toluene. 40 mass parts of thionyl chloride was added here, and it stirred at 60 degreeC. After confirming the formation of the target compound (d) by TLC, the solvent and thionyl chloride were distilled off under reduced pressure to obtain 35 parts by mass of the target (d).

<Synthesis Example 2-1: Synthesis of cellulose compound (A)>
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. The compound (a) previously dissolved in 200 parts by mass of acetone was added dropwise over 30 minutes, the internal temperature was raised to 40 ° C., and the mixture was stirred for 5 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 40-50 ° C.
After filtration, vacuum drying was performed to obtain 60 parts by mass of cellulose compound A. When the number average molecular weight of the obtained cellulose compound A was determined by GPC measurement, it was M _n = 89500.

<Synthesis Example 2-2: Synthesis of Cellulose Compound B>
A cellulose compound B was obtained in the same manner as in Synthesis Example 2-1 except that the compound (a) was changed to the compound (b). It was _Mn = 91200 when the number average molecular weight of the obtained cellulose compound B was calculated | required by GPC measurement.

<Synthesis Example 2-3: Synthesis of cellulose compound C>
A cellulose compound C was obtained in the same manner as in Synthesis Example 2-1 except that the compound (a) was changed to 9-fluorenylmethoxycarbonyl chloride. It was _Mn = 85700 when the number average molecular weight of the obtained cellulose compound C was calculated | required by GPC measurement.

<Synthesis Example 2-4 (Comparative Example): Synthesis of Comparative Cellulose Compound F>
A comparative cellulose compound F was obtained in the same manner as in Synthesis Example 2-1 except that the compound (a) was changed to the compound (d). When the number average molecular weight of the obtained comparative cellulose compound D was determined by GPC measurement, it was M _n = 97200.

The average substitution degree of the cellulose compounds A to D was as shown in Table 1 below. In the general formula (1), X ¹ , X ² , and X ³ are all * -OCO- (* represents a bond on the main chain side).

<Calculation of absorption transition moment>
The absorption transition moment of the structure used as the substituent B was calculated. In the calculation, the following structure was used as a substituent model. The calculation of the transition moment is described in Gaussian 03, Revision C. 02 (Gaussian, USA), B3LYP / 6-31 Giga (D) level DFT calculation, structure optimization, and B3LYP / 6-31 + g (D) level TD-DFT calculation It was. As shown in Table 2, the model of the substituents of cellulose compounds A to C has a larger transition moment in the X-axis direction than the transition moment in the Y-axis direction. It can be seen that the transition moment in the X-axis direction is smaller than the transition moment in the Y-axis direction.

[Example 2: Production of cellulose compound film]
<Preparation of cellulose body solution>
The following raw materials were put into a mixing tank and dissolved by stirring while heating to prepare a cellulose body solution having a mass part composition described in Table 3 below.
In addition, as a comparative compound, E: cellulose acetate (Daicel Chemical Industries, Ltd., acetyl substitution degree 2.86), F: cellulose acetate butyrate (Eastman Chemicals, product code 381-20) were used.

<Production of Cellulose Compound Film Samples 001 to 006>
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). About the produced cellulose acetate film, Re value in wavelength 450nm, 550nm, and 630nm was measured by the above-mentioned method. The results are shown in Table 4.

From Table 4, it can be seen that the film made of the cellulose compound of the present invention has excellent Re developability and satisfies the following mathematical formulas (V) and (VI).
Formula (V) 0.5 <Δn (450 nm) / Δn (550 nm) <1.0
Formula (VI) 1.05 <Δn (630 nm) / Δn (550 nm) <1.5

[Example 3: Polarizing plate protective film]
Using the samples 001 to 005 of Example 2, elliptically polarizing plate samples 101 to 105 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 with the 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 4: Production and evaluation of optical compensation film]
Instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, the cellulose film 001 to 003 of the present invention of Example 2 was used, which was disclosed in JP-A-2002-62431. The bend-aligned liquid crystal cell described in Example 9 was attached at 25 ° C. and 60% relative humidity, and was brought into 25 ° C. and 10% relative humidity. When the cellulose film of the present invention was used, good display performance with little leakage and little change in contrast was obtained.

Furthermore, in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, an optical compensation filter film was produced by changing to the cellulose films 001 to 003 of the present invention. 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 films 001 to 003 of the present invention are the liquid crystal display device described in Example 1 of Japanese Patent Laid-Open No. 10-48420, and examples of Japanese Patent Laid-Open No. 9-26572. 1, an optically anisotropic layer containing discotic liquid crystal molecules, 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, When used in the 20-inch OCB type liquid crystal display device shown in FIGS. 10 to 15 of 2000-154261 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 the cellulose acylate D outside the present invention, light leakage was observed when black display was performed under dark.

Claims (10)

A cellulose compound represented by the following general formula (1):

In general formula (1), n represents an average degree of polymerization and is an integer of 10 to 1500. X ² , X ³ and X ⁶ are each independently a linkage of * —O—, * —OC (═O) — or * —OC (═O) —NH— (* represents a bond on the main chain side). Represents a group. R ² , R ³ , and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituent represented by the following general formula (2). n —X ² —R ² , —X ³ —R ^3, or —X ⁶ —R ⁶ may be different for each structural unit, and n presents R ² , R ³ , and R ^6. Among these, at least one is a substituent represented by the following general formula (2).

(In General Formula (2), L represents a single bond or an alkylene group having 1 to 20 carbon atoms, and —CH ₂ — constituting the alkylene group represents —O—, —S—, —NR— (R represents hydrogen V represents C, CH, or N, P and Q are residues that form a ring structure α having an aromatic group, and have a substituent. may. a carbon atom or a nitrogen atom in this case V and ^{V *, P} * the atom bonded to the ^{V *} in P and Q, respectively, when the ^{Q *,} V * ^-P * -Q ^* of On the plane formed by three atoms, if the direction parallel to P ^* -Q ^* is the X axis and the direction perpendicular to the X axis on the plane is the Y axis, the magnitude of the transition moment of absorption of the ring structure α Is larger in the order of the X-axis direction and the Y-axis direction, provided that the transition moment is (This is a value obtained by calculating the transition moment of absorption of the compound represented by formula (3).)

(In general formula (3), V, P, Q and ring structure α have the same meanings as in general formula (2).) Wherein ^-X 2 ^-R 2, a substituent represented by ^-X 3 -R ^3, and ^-X 6 -R ^6, in the ^R 2, ^{R 3,} and ^{R 6} is the formula (2) The cellulose compound according to claim 1, wherein the average substitution degree (B) of the substituents represented satisfies the following formula (I).
Formula (I) 0.1 <(B) <2.5
However, the ^-X 2 ^-R 2 in cellulose compound, ^-X 3 -R ^3, and the average degree of substitution sum of the substituents represented by ^{-X 6 -R 6 (-X 2 -R} 2) + (- ^{X 3 -R 3) + (-} X 6 -R 6) is 3.0. Wherein ^-X 2 ^-R 2, a substituent represented by ^-X 3 -R ^3, and ^-X 6 -R ^6, wherein ^R 2, ^{R 3,} and alkyl ^{R 6} is from 1 to 10 carbon atoms The average degree of substitution (A) of the substituent which is a group, and the average degree of substitution (B) of the substituent in which R ² , R ³ and R ⁶ are represented by the general formula (2) are represented by the following formula (I The cellulose compound according to claim 2, which satisfies () to (III).
Formula (I) 0.1 <(B) <2.5
Formula (II) 0.5 <(A) <2.9
Formula (III) 0.6 <(A) + (B) <3.0
However, the ^-X 2 ^-R 2 in cellulose compound, ^-X 3 -R ^3, and the average degree of substitution sum of the substituents represented by ^{-X 6 -R 6 (-X 2 -R} 2) + (- ^{X 3 -R 3) + (-} X 6 -R 6) is 3.0.   The ring structure α is a structure containing at least one selected from the group consisting of a nitrogen-containing five-membered ring, a nitrogen-containing six-membered ring, an aromatic hydrocarbon, and an alicyclic hydrocarbon. The cellulose compound according to claim 1. The cellulose compound according to claim ¹ , wherein X ¹ , X ² and X ³ are * —OC (═O) — (* represents a bond on the pyranose ring side).   A polymer composition comprising at least one cellulose compound according to any one of claims 1 to 5.   An optical film formed from the polymer composition according to claim 6.   A retardation film comprising the optical film according to claim 7. A birefringence at a specific wavelength, wherein the birefringence Δn (550 nm) is positive with respect to the orientation direction, comprising at least one polymer composition according to claim 6 and subjected to an orientation treatment such as stretching. A retardation plate having a film in which Δn satisfies the following formulas (V) and (VI):
Formula (V) 0.5 <Δn (450 nm) / Δn (550 nm) <1.0
Formula (VI) 1.05 <Δn (630 nm) / Δn (550 nm) <1.5   10. A polarizing plate comprising the retardation plate according to claim 8 disposed on at least one side of a polarizer.