JP2007332188A - Method for producing cellulose ester film and cellulose ester film obtained by the method, optically compensating film, polarized plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a cellulose ester film, by which the cellulose ester film having small retardation values in inplane and film thickness directions and having excellent planarity can effectively be produced at a low cost, and to provide an optically compensating film, a polarized plate and a liquid crystal display device each using the cellulose ester film. <P>SOLUTION: This method for producing the cellulose ester film having a specific inplane retardation value and a specific film thickness retardation value, comprises a process for casting a dope prepared by dissolving a cellulose ester in a solvent on a support, a process for peeling the film from the support, and a process for drying the peeled film, is characterized by using at least a cellulose ester originated from at least one kind of cotton linters and a cellulose ester originated from at least one kind of wood pulp, wherein the content of the cotton linter-originated cellulose esters in the total cellulose esters is 5 to 90 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a cellulose ester film useful for a liquid crystal display device. Furthermore, the present invention relates to a cellulose ester film produced by the method, an optical compensation film using the same, a polarizing plate and a liquid crystal display device.

Conventionally, cellulose ester films such as cellulose acylate films have been used for photographic supports and various optical materials because of their toughness and flame retardancy. In particular, in recent years, it has been widely used as an optical transparent film for liquid crystal display devices. Cellulose ester films, such as cellulose acylate films, are excellent as optical materials for devices that handle polarized light such as liquid crystal display devices because of their high optical transparency and high optical isotropy. So far, it has been used as a support for a protective film for a polarizer and an optical compensation film capable of improving the display viewed from an oblique direction (viewing angle compensation).
A polarizing plate, which is one of the members for a liquid crystal display device, has a polarizer protective film bonded to at least one side of the polarizer. A general polarizer is obtained by dyeing a stretched polyvinyl alcohol (PVA) film with iodine or a dichroic dye. In many cases, as a polarizer protective film, a cellulose acylate film, particularly a triacetyl cellulose film, which can be directly bonded to PVA is used. It is important that the polarizer protective film is excellent in optical isotropy, and the optical characteristics of the polarizer protective film greatly influence the characteristics of the polarizing plate.

  In recent liquid crystal display devices, improvement in viewing angle characteristics is strongly demanded, and optically transparent films such as a protective film for a polarizer and a support for an optical compensation film are more optical. It is required to be isotropic. In order to be optically isotropic, it is important that the retardation value represented by the product of birefringence and thickness of the optical film is small. In particular, in order to improve display from an oblique direction, it is necessary to reduce not only the retardation (Re) in the front direction but also the retardation (Rth) in the film thickness direction. Specifically, when the optical properties of the optical transparent film are evaluated, the Re measured from the front of the film is small, and it is required that the Re does not change even if the angle is changed.

  Therefore, an optical transparent film with a small angle change of Re was proposed using a polycarbonate film or a thermoplastic cycloolefin film instead of a cellulose acylate film (ZEONOR (manufactured by ZEON Corporation) or ARTON (manufactured by JSR Corporation). )Such). However, when these optically transparent films are used as a protective film for a polarizer, there is a problem in bonding properties with PVA because the film is hydrophobic. Another problem is that the optical characteristics of the entire film surface are not uniform. On the other hand, in Patent Document 1, the cellulose acylate film excellent in the bonding suitability to PVA is improved by further reducing the optical anisotropy, the front Re is almost zero, and the retardation angle change is small. That is, an optically isotropic film having an optical isotropy in which Rth is almost zero has been proposed. The patent document discloses that the optical anisotropy can be reduced by increasing the acyl group substitution degree of cellulose acylate.

JP 2005-120352 A

  In addition, for cellulose ester films used as optical films, such as cellulose acylate films, it is desired to produce a film with little variation in film thickness and excellent flatness at low cost with high productivity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for efficiently and inexpensively producing a cellulose ester film having a small in-plane and thickness retardation and excellent flatness. Is to provide.
A further object of the present invention is to provide an optical compensation film, a polarizing plate and a liquid crystal display device using the cellulose ester film which is inexpensive and has excellent flatness and optical properties.

As a result of intensive studies by the present inventors, a cellulose ester film excellent in flatness was successfully produced at low cost with high productivity by adjusting the raw material of cellulose ester. Specifically, by using cotton derived from cotton linter to some extent, it reduces the peeling resistance from the support of the film in the manufacturing process and keeps the film flatness good, and compared with cotton linter in a range where peeling does not become a problem. We succeeded in producing a film with low cost and high productivity by reducing the manufacturing cost by using low-cost wood pulp derived cotton.
The above object of the present invention has been achieved by the following constitution.

(1) In-plane retardation value Re ₍₅₉₀₎ including a step of casting a dope obtained by dissolving a cellulose ester in a solvent onto a support, a step of peeling the film from the support, and a step of drying the peeled film. And a method of producing a cellulose ester film having a retardation value Rth _{(590) in the} film thickness direction satisfying the following formulas (I) and (II), and at least one cellulose ester derived from at least one cotton linter as the cellulose ester: A method for producing a cellulose ester film, wherein at least a cellulose ester derived from wood pulp is used, and the ratio of the cotton linter-derived cellulose ester in the total cellulose ester is 5% by mass or more and 90% by mass or less.
Formula (I) 0 ≦ Re ₍₅₉₀₎ ≦ 10
Formula (II) −25 ≦ Rth ₍₅₉₀₎ ≦ 25
[Wherein, Re _(λ) is an in-plane retardation value (unit: nm) at 25 ° C. and 60% RH at a wavelength of λ nm. Rth _(λ) is a retardation value (unit: nm) in the film thickness direction at a wavelength of λ nm at 25 ° C. and 60% RH. ]
(2) In (1), the cellulose ester derived from the cotton linter and the cellulose ester derived from the wood pulp are both acylated esters, and the acyl substitution degree (X + Y) satisfies the following formula (10). The manufacturing method of the cellulose-ester film of description.
Formula (10) 2.7 <X + Y ≦ 3.0
[Wherein, X is the degree of acetyl substitution, and Y is the degree of acyl substitution other than acetyl. ]
(3) The quotient obtained by dividing the larger value of the 6% viscosity of the cotton linter-derived cellulose ester and the 6% viscosity of the wood pulp-derived cellulose ester by the smaller value is 1.2 or more. The method for producing a cellulose ester film according to (1) or (2), which is characterized in that
(4) A cellulose ester film produced by the method for producing a cellulose ester film according to any one of (1) to (3).
(5) The cellulose ester film according to (4), wherein the cellulose ester film contains a retardation reducing agent.
(6) The cellulose ester film according to (4) or (5), wherein the cellulose ester film contains a retardation wavelength dispersion adjusting agent.
(7) The cellulose ester film according to any one of (4) to (6), wherein a maximum height Ry of surface irregularities of the cellulose ester film is 0.5 μm or less.
(8) The cellulose ester film according to any one of (4) to (7), wherein the cellulose ester film has a thickness of 30 to 120 μm.
(9) The cellulose ester film is characterized by having a retentivity of 2.0% or less after 10 times the treatment at 80 ° C. and 90% RH for 20 hours after conditioning at 25 ° C. and 50% RH for 4 hours ( The cellulose ester film according to any one of 4) to (8).
(10) An optically anisotropic layer having Re ₍₅₉₀₎ = 0 to 200 nm and | Rth ₍₅₉₀₎ | = 0 to 400 nm is formed on the cellulose ester film according to any one of (4) to (9). An optical compensation film characterized by being laminated.
(11) In the polarizing plate in which a protective film is bonded to both sides of the polarizing film, at least one of the protective films is a cellulose ester film according to any one of (4) to (9) or (10). A polarizing plate, which is an optical compensation film.
(12) The cellulose ester film according to any one of (4) to (9), the optical compensation film according to (10), and the polarizing plate according to (11) are used. A liquid crystal display device.

  According to the present invention, a cellulose ester film having small optical anisotropy (Re, Rth) and substantially optical isotropy and excellent flatness can be produced at low cost with high productivity.

  Hereinafter, the present invention will be described in detail.

<Optical properties of cellulose ester film>
[Retardation of cellulose ester film]
The in-plane retardation value Re ₍₅₉₀₎ value at a wavelength of 590 nm of the cellulose ester film of the present invention at 25 ° C. and 60% RH satisfies the following formula (I). In this formula, the unit of Re is expressed in nm.
Formula (I) 0 ≦ Re ₍₅₉₀₎ ≦ 10

A more preferable range of the Re ₍₅₉₀₎ value is 0 nm to 7 nm, more preferably 0 nm to 5 nm, and particularly preferably 0 nm to 2 nm.

The retardation value Rth ₍₅₉₀₎ in the film thickness direction at a wavelength of 590 nm under 25 ° C. and 60% RH satisfies the following formula (II). In this formula, the unit of Rth is expressed in nm.
Formula (II) −25 ≦ Rth ₍₅₉₀₎ ≦ 25

A more preferable range of the Rth ₍₅₉₀₎ value is −20 nm to 20 nm, more preferably −15 nm to 15 nm, and particularly preferably −10 nm to 10 nm.

  The cellulose ester film of the present invention having a small retardation in the film thickness direction has a feature that it does not cause excessive birefringence in the film thickness direction. By using the cellulose ester film of the present invention, the optical properties of the liquid crystal display device The degree of freedom of design can be remarkably increased. In particular, when a cellulose ester film having a small retardation in the plane and in the film thickness direction is used as a support for a polarizing plate protective film or an optical compensation film, the optical compensation ability of the optical compensation layer in other members or the optical compensation film is improved. It is possible to use the birefringence of these members as they are without disturbing them.

  As means for achieving the above formulas (I) and (II), for example, the ester substituent of the raw material cellulose ester described later is preferable, the ester substitution degree of the raw material cellulose ester is within a preferable range, and Can be achieved by a combination of the ester substitution degree of the raw material cellulose ester, the amount of the retardation reducing agent used, and the amount of the retardation wavelength dispersion adjusting agent used.

  The in-plane retardation Re and the retardation Rth in the film thickness direction of the cellulose ester film of the present invention are preferably both small in change due to humidity, and preferably satisfy the following formulas (III) and (IV).

Formula (III) | Re _10% −Re _80% | ≦ 25
Formula (IV) | Rth _10% −Rth _80% | ≦ 35
[In Formula (III), Re _10% is at 25 ° C. under 10% RH, Re _80% is at 25 ° C. under 80% RH, in-plane retardation at a wavelength of 590 nm, and in Formula (IV), Rth _10% is 25 ° C. Under 10% RH, Rth _80% represents retardation in the film thickness direction at 25 ° C. and 80% RH at a wavelength of 590 nm. ]
A more preferable range of | Re _10% -Re _80% | is 0 to 20 nm, and more preferably 0 to 15 nm.
The more preferable range of | Rth _10% -Rth _80% | is 0 to 25 nm, and more preferably 0 to 15 nm.

Also, the difference between the Re value at a wavelength of 450 nm at 25 ° C. and 10% RH and the Re value at a wavelength of 450 nm at 25 ° C. and 80% RH, | Re _{10% (450)} −Re _{80% (450)} | The difference between the Re value at a wavelength of 630 nm at 10 ° C. and the Re value at a wavelength of 630 nm at 80 ° C. at 25 ° C., | Re _{10% (630)} −Re _{80% (630)} | is preferably 25 nm or less. .
Further, the difference between the Rth value at a wavelength of 450 nm at 25 ° C. and 10% RH and the Rth value at a wavelength of 450 nm at 25 ° C. and 80% RH, | Rth _{10% (450)} −Rth _{80% (450)} | Preferably, the difference between the Rth value at a wavelength of 630 nm at 25 ° C. and 80% RH at 25 ° C. and the Rth value at a wavelength of 630 nm, | Rth _{10% (630)} −Rth _{80% (630)} | .

The cellulose ester film of the present invention has a difference between Re and Rth at wavelengths of 450 nm and 630 nm, | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | and | Rth ₍₄₅₀₎ −Rth _{(630) at} 25 ° C. and 60% RH. | Is preferably small, and | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 10 and | Rth ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 35. More preferably, | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 5 and | Rth ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 25, and | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 3 and | Rth It is particularly preferable that ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 15.
Further, it is preferable that | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 15 and | Rth ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 40 at 25 ° C. under 10% RH and 25 ° C. under 80% RH. More preferably, | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 10 and | Rth ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 30, and | Re ₍₄₅₀₎ −Re ₍₆₃₀₎ | ≦ 5 and | Rth It is particularly preferable that ₍₄₅₀₎ −Rth ₍₆₃₀₎ | ≦ 25.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light with a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotating axis) (if there is no slow axis, any in-plane The light is incident at a wavelength of λ nm from the inclined direction in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction of KOBRA 21ADH or WR calculates based on the measured retardation value, the assumed average refractive index, and the input film thickness value.
In the above, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the slow axis in the plane from the normal direction as the rotation axis, the retardation value at a tilt angle larger than the tilt angle is After changing the sign to negative, KOBRA 21ADH or WR calculates.
Note that the retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotary axis) (in the case where there is no slow axis, the arbitrary direction in the film plane is the rotary axis), Rth can also be calculated from the following formula (1) and formula (2) based on the value, the assumed value of the average refractive index, and the input film thickness value.
Formula (1)

Note: Re (θ) above represents the retardation value in the direction inclined at an angle θ from the normal direction.
In formula (1), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. .
Rth = ((nx + ny) / 2-nz) xd --- Formula (2)
In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optic axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) as the slow axis (indicated by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis). Measured 11 points by entering light of wavelength λ nm from each inclined direction in 10 degree steps, and based on the measured retardation value, assumed average refractive index value and input film thickness value, KOBRA 21ADH or WR Is calculated.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (JOHN WILEY & SONS, INC) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx-nz) / (nx-ny) is further calculated from the calculated nx, ny, and nz.

[Retardation variation]
The dispersion of the retardation value is 100 m in the longitudinal direction at 5 points in the width direction of the film (center, end (5% of the total width from both ends, and 2 points in the middle and end)). The difference between the maximum value and the minimum value of the values sampled every time is preferably 10 nm or less, more preferably 5 nm or less, and particularly preferably 1 nm or less.

[Material of cellulose ester film]
As a raw material of the cellulose ester film of the present invention, the cellulose ester described below can be used, and other components such as various compounds and additives described later can be appropriately used.

<Cellulose ester>
The glucose unit forming cellulose has three hydroxyl groups that can be bonded. For example, in cellulose triacetate, when all three hydroxyl groups of the glucose unit are bonded to acetyl groups, the degree of substitution with acetyl groups Is 3.0. In this case, the higher the substitution degree of the cellulose ester, the smaller the retardation in the film thickness direction, which is preferable. Cellulose acylate has the property that the intrinsic birefringence changes from positive to negative as the degree of substitution increases. Cellulose acylate having a high degree of substitution and a negative intrinsic birefringence can reduce the retardation in the film thickness direction by stretching.
The measuring method of the substitution degree of these acyl groups can be measured according to ASTM-D817-96.
A preferable ester substitution degree of the cellulose ester is a cellulose ester satisfying the following formula (10) when the acetyl substitution degree by acetic acid is represented by X and the ester substitution degree by other than acetic acid such as propionic acid or butyric acid is represented by Y.

  Formula (10) 2.7 <X + Y ≦ 3.0

  This is preferable for reducing Rth when X + Y is larger than 2.7 and within a range of 3.0 or less. More preferably, it is 2.85-3.00, More preferably, it is 2.91-2.98.

  The basic principle of the cellulose acylate synthesis method is described in Mita et al., “Wood Chemistry”, Kyoritsu Shuppan, 1968, pages 180-190. A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylated mixed solution to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After completion of the acylation reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. Cellulose acylate solution can be obtained by adding cellulose acylate solution (or by adding water or dilute sulfuric acid into cellulose acylate solution) and aggregating and separating cellulose acylate, and washing and stabilizing treatment. .

The cellulose ester used as a raw material of the cellulose ester film of the present invention contains at least one cellulose derived from a cotton linter and at least one derived from a wood pulp as the cellulose ester raw material. Moreover, the cellulose ester derived from cotton linter, kenaf other than wood pulp, etc. can be included. In the present invention, the content (also referred to as linter ratio) of the cellulose ester derived from the cotton linter in the total cellulose ester is 5% by mass or more and 90% by mass or less. That is, the ratio of linter / pulp (including kenaf) is 5% by mass / 95% by mass to 90% by mass / 10% by mass.
When the linter ratio is less than 5%, the peelability described later may deteriorate, which is not preferable. On the other hand, when the linter ratio exceeds 90%, the ratio of cellulose ester produced from inexpensive wood pulp is inevitably small, and the cost cannot be sufficiently reduced, which is not preferable.
The linter / pulp ratio is preferably 10% by mass / 90% by mass to 75% by mass / 25% by mass, and more preferably 20% by mass / 80% by mass to 50% by mass / 50% by mass.

Examples of the cellulose ester used in the present invention include triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB), cellulose acetate phthalate, cellulose acetate trimellitate, In addition to aliphatic carboxylic acids such as cellulose nitrate, inorganic acids, carboxylic acids having aromatic rings, polycarboxylic acids such as dicarboxylic acids and tricarboxylic acids, and partial esters of polyvalent carboxylic acids (cellulose acetate benzoate) Of cellulose esters.
The cellulose ester used in the present invention is composed of at least two different types of cellulose, at least one type is derived from cotton linter, and at least one type is derived from cellulose derived from wood pulp, each of which is 91% by mass of methylene chloride and 9% by mass of methanol. Viscosity (also referred to as 6% viscosity) of a solution dissolved at a concentration of 6% by mass in a mixed solvent consisting of is different, and its quotient (a value obtained by dividing a large viscosity value by a small viscosity value) is 1.2 or more and 6.0 or less. It is preferable that
This is because cellulose esters having different cellulose ester types and viscosities (related to the average degree of polymerization) are considered to contribute to the formation of a special internal structure, and the effect of not deteriorating the dope releasability described later , It is presumed to bring about the effect of increasing the retention of the additive.
A more preferable range of the quotient of 6% viscosity is 1.6 or more and 4.8 or less, and 2.0 or more and 4.0 or less.
The preferable value of the 6% viscosity is 250 to 1000 mPa · s with the larger viscosity value, and 60 to 830 mPa · s with the smaller viscosity value.
The 6% viscosity can be measured using a commercially available capillary viscometer, or various rheometers such as a cone / plate rheometer and a parallel plate rheometer.

  In addition, the degree of polymerization of the cellulose ester of the present invention is preferably 200 to 800, more preferably 250 to 650, in terms of viscosity average degree of polymerization, from the viewpoint of satisfying the above-mentioned 6% viscosity quotient condition. The viscosity average degree of polymerization can be measured according to Uda et al.'S limiting viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Science, Vol. 18, No. 1, pages 105-120, 1962). A method for measuring the viscosity average degree of polymerization is also described in JP-A-9-95538.

If the molecular weight of the film is large, the modulus of elasticity will increase, but if the molecular weight is increased too much, the viscosity of the cellulose ester solution will become too high, so that the above conditions will not be met and wind unevenness will occur, resulting in increased productivity. It tends to decrease. The molecular weight of the cellulose ester is preferably 50,000 to 200,000 in terms of number average molecular weight (Mn), more preferably 100,000 to 200,000. The cellulose ester used in the present invention preferably has an Mw / Mn ratio of 1.6 to 4.5, more preferably 2.4 to 3.6.
The molecular weight can be controlled by changing the temperature and time of the esterification reaction of cellulose as well as the amount of water during the reaction.

  Since the average molecular weight and molecular weight distribution of the cellulose ester can be measured using high performance liquid chromatography, the number average molecular weight (Mn) and the mass average molecular weight (Mw) can be calculated using this, and the ratio can be calculated.

The measurement conditions are as follows.
Solvent: Methylene chloride column: Shodex K806, K805, K803G (used by connecting 3 products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

<Retardation reducing agent>
The cellulose ester film of the present invention may contain a retardation reducing agent.
The retardation reducing agent preferably used in the present invention is a compound that reduces the retardation in the film thickness direction, and specific examples include compounds represented by the following general formula (1) and general formula (2). It is mentioned, but is not limited to this.
Any of the compounds of the general formula (1) can be produced from known compounds. That is, it can be obtained by a substitution reaction between a sulfonyl chloride derivative and an amine derivative. The compound of the general formula (2) can also be obtained by a dehydration condensation reaction between carboxylic acids and amines using a condensing agent or a substitution reaction between a carboxylic acid chloride derivative and an amine derivative.

In the general formula (1), R ¹¹ represents an alkyl group or an aryl group, and R ¹² and R ¹³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. The total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is preferably 10 or more. In R ¹¹ , R ¹² and R ¹³ , each alkyl group or aryl group may have a substituent.

  As the substituent for the alkyl group or aryl group, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are more preferable. . Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable.

  Although the preferable example of a compound represented by General formula (1) is shown below, it is not limited to these specific examples.

Next, the compound of General formula (2) is demonstrated.
In the formula, R ¹⁴ represents an alkyl group or an aryl group, and R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom, an alkyl group or an aryl group. Moreover, the alkyl group and the aryl group may have a substituent.

More preferably, R ¹⁴ , R ¹⁵ and R ¹⁶ each independently represents an alkyl group or an aryl group. Here, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and 1 to 12 carbon atoms. Is most preferred. As the cyclic alkyl group, a cyclohexyl group is particularly preferable. The aryl group preferably has 6 to 36 carbon atoms, and more preferably 6 to 24 carbon atoms.

  The above alkyl group and aryl group may have a substituent, such as a halogen atom (for example, chlorine, bromine, fluorine and iodine), an alkyl group, an aryl group, an alkoxy group, an aryloxy group, acyl Group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, sulfonylamino group, hydroxy group, cyano group, amino group and acylamino group, more preferably halogen atom, alkyl group, aryl group, alkoxy group, aryloxy group A sulfonylamino group and an acylamino group, particularly preferably an alkyl group, an aryl group, a sulfonylamino group and an acylamino group.

  Although the preferable example of a compound represented by General formula (2) below is shown below, it is not limited to these specific examples.

These letter reduction agents have a function of reducing optical anisotropy.
By containing a compound that lowers this retardation, a compound that suppresses the orientation of the polymer in the cellulose ester film in the in-plane and in the film thickness direction is used. Can be sufficiently reduced, Re can be close to zero, and Rth can be negative. The compound which lowers the letter distortion is sufficiently compatible with the polymer, and it is advantageous that the compound itself does not have a rod-like structure or a planar structure. Specifically, when a plurality of planar functional groups such as aromatic groups are provided, a structure having these functional groups in a non-planar rather than the same plane is advantageous.

The addition amount of the retardation reducing agent can be determined as long as it is compatible with the cellulose ester and other components. In many cases, the solid content of the cellulose ester is approximately 40% by mass or less, preferably 0 to 30% by mass, and particularly preferably 0 to 20% by mass.
These retardation reducing agents may be used alone or in combination of two or more compounds at an arbitrary ratio.

(Log P value)
In producing the cellulose ester film of the present invention, among the compounds that reduce the optical anisotropy by inhibiting the cellulose ester in the film from being oriented in the plane and in the film thickness direction as described above, octanol-water A compound having a partition coefficient (log P value) of 0 to 7 is preferred. A compound having a log P value of 7 or less is preferred because it is highly compatible with cellulose ester and hardly causes clouding or powder blowing of the film. In addition, a compound having a log P value of 0 or more is preferable in that the hydrophilicity is not too high and the water resistance of the cellulose ester film is hardly deteriorated. A more preferable range for the logP value is 1 to 6, and a particularly preferable range is 1.5 to 5.

  The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000). Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement. As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987)), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29, 163). (1989)), Broto's fragmentation method (Eur. J. Med. Chem. Chim. Theor., 19, 71 (1984).) And the like are preferably used, but the Crippen's fragmentation method (J. Chem. Inf. .Comput.Sci., 27, 21 (1987)) is more preferable. When the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within the scope of the present invention by the Crippen's fragmentation method.

  The cellulose ester film of the present invention preferably contains at least one compound that reduces optical anisotropy (retardation reducing agent) within a range that satisfies the following formulas (a) and (b).

(A) (Rth (A) −Rth (0)) / A ≦ −1.0
(B) 0.01 ≦ A ≦ 100

[Wherein Rth (A) is an Rth value of a wavelength of 590 nm at 25 ° C. and 60% RH of a film containing A% of a compound that lowers Rth, and Rth (0) is 25 of a film not containing a compound that lowers Rth. Rth value at a wavelength of 590 nm at 60 ° C. and 60% RH, and A is the mass (%) of the compound when the solid content mass of the polymer is 100. ]

In the above formulas (a) and (b), (a1) (Rth (A) −Rth (0)) / A ≦ −2.0
(B1) 0.05 ≦ A ≦ 50
More preferably,
(A2) (Rth (A) −Rth (0)) / A ≦ −3.0
(B2) 0.1 ≦ A ≦ 20
More preferably.

<Wavelength dispersion modifier>
The cellulose ester film of the present invention desirably has a small dependency of Re and Rth on the wavelength, that is, wavelength dispersion. As a means for reducing the wavelength dispersion, in the present invention, it is effective to add a compound (hereinafter also referred to as a wavelength dispersion adjusting agent) that adjusts the wavelength dispersion to the cellulose ester film.
The wavelength dispersion adjusting agent is preferably a compound that reduces the wavelength dispersion ΔRth of Rth represented by the following formula (c) = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |, and the cellulose ester film of the present invention comprises: It is preferable to contain at least one of these compounds within the range satisfying the following formulas (d) and (e).

(C) ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |
(D) (ΔRth (B) −ΔRth (0)) / B ≦ −2.0
(E) 0.01 ≦ B ≦ 30
[In the formula, ΔRth (B) is a ΔRth value at 25 ° C. and 60% RH of a film containing B% of a compound that adjusts Rth wavelength dispersion, and ΔRth (0) does not contain a compound that adjusts Rth wavelength dispersion. The ΔRth value of the film, and B is the mass (%) of the compound when the solid content mass of the polymer is 100. ]

The above formulas (d) and (e) are: (d1) (ΔRth (B) −ΔRth (0)) / B ≦ −3.0
(E1) 0.05 ≦ B ≦ 25
More preferably,
(D2) (ΔRth (B) −ΔRth (0)) / B ≦ −4.0
(E2) 0.1 ≦ B ≦ 20
More preferably.

The chromatic dispersion adjusting agent has absorption in the ultraviolet region of 200 to ₄₀₀ nm, and ΔRe = | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | and ΔRth = | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | More preferably, the compound is a compound that lowers the wavelength, and the wavelength dispersion of Re and Rth of the cellulose ester film can be more effectively adjusted by including at least one such compound.

  The Re and Rth values of the cellulose ester film generally have a wavelength dispersion characteristic that is larger on the long wavelength side than on the short wavelength side. Therefore, it is required to smooth the chromatic dispersion by increasing Re and Rth on the relatively short wavelength side. On the other hand, a compound having absorption in the ultraviolet region of 200 to 400 nm has a wavelength dispersion characteristic in which the absorbance on the short wavelength side is larger than that on the long wavelength side. If the compound itself is isotropically present inside the cellulose ester film, it is assumed that the birefringence of the compound itself, and thus the wavelength dispersion of Re and Rth, is larger on the short wavelength side as the wavelength dispersion of absorbance.

  Therefore, as described above, by using the compound having absorption in the ultraviolet region of 200 to 400 nm and assuming that the wavelength dispersion of Re and Rth of the compound itself is larger toward the short wavelength side, the Re and Rth of the cellulose ester film are used. Chromatic dispersion can be prepared. For this purpose, the compound for adjusting the wavelength dispersion is required to be sufficiently uniformly compatible with the polymer solid content. The absorption band range in the ultraviolet region of such a compound is preferably 200 to 400 nm, more preferably 220 to 395 nm, and even more preferably 240 to 390 nm.

  In recent years, liquid crystal display devices such as televisions, notebook personal computers, and mobile portable terminals have been required to have excellent transmittance of optical members used in liquid crystal display devices in order to increase luminance with less power. Therefore, when adding a wavelength dispersion adjusting agent to a cellulose ester film, it is preferable to use one having excellent spectral transmittance. As the spectral transmittance of the wavelength dispersion adjusting agent, the spectral transmittance at a wavelength of 380 nm is preferably 45% or more and 95% or less, and the spectral transmittance at a wavelength of 350 nm is more preferably 10% or less.

  Since the wavelength dispersion adjusting agent is preferably not volatilized during the dope casting and drying process for preparing the cellulose ester film, the molecular weight is preferably 250 to 1,000. More preferably, it is 260-800, More preferably, it is 270-800, Most preferably, it is 300-800. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.

The addition amount of the wavelength dispersion adjusting agent is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, and more preferably 0.2 to 10% by mass of the solid content of the polymer. It is particularly preferred.
These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.

  Specific examples of the wavelength dispersion adjusting agent preferably used in the present invention include, for example, benzotriazole compounds, benzophenone compounds, compounds containing a cyano group, oxybenzophenone compounds, salicylic acid ester compounds, nickel complex compounds, and the like. However, the present invention is not limited to these compounds.

As the benzotriazole-based compound, those represented by the following general formula (101) are preferably used.
Formula ^{(101): Q 101 -Q 102} -OH
(In the formula, Q ¹⁰¹ represents a nitrogen-containing aromatic heterocycle, and Q ¹⁰² represents an aromatic ring.)

Q ¹⁰¹ represents a nitrogen-containing aromatic heterocycle, preferably a 5- to 7-membered nitrogen-containing aromatic heterocycle, more preferably a 5- to 6-membered nitrogen-containing aromatic heterocycle. For example, imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, naphthoxazole, azabenzimidazole, purine, pyridine, pyrazine , Pyrimidine, pyridazine, triazine, triazaindene, tetrazaindene and the like, more preferably a 5-membered nitrogen-containing aromatic heterocycle, specifically, imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole. , Benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole, particularly preferably benzotriazole That.
The nitrogen-containing aromatic heterocycle represented by Q ¹⁰¹ may further have a substituent, and the substituent T described below can be applied as the substituent. In addition, when there are a plurality of substituents, each may be condensed to form a ring.

The aromatic ring represented by Q ¹⁰² is not particularly limited, and may be aromatic heterocyclic ring with an aromatic hydrocarbon ring, but is preferably an aromatic hydrocarbon ring. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring or a naphthalene ring), and has 6 to 20 carbon atoms. It is more preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, particularly preferably a naphthalene ring or a benzene ring, and most preferably a benzene ring. .

  Although it does not specifically limit as an aromatic heterocycle, Preferably it is an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of this aromatic heterocycle include thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline. Phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. Of these, pyridine, triazine, and quinoline are preferable.

Q ¹⁰² may further have a substituent, and the following substituent T is preferred.
Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, propargyl, 3-pentynyl, etc.), an aryl group (preferably having 6 to 30 carbon atoms) Preferably it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, etc.), substituted or unsubstituted amino groups (preferably 0 to 20 carbon atoms). More preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc.), an alkoxy group (preferably having 1 carbon atom). To 20, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methoxy, ethoxy, butoxy, etc.), an aryloxy group (preferably 6 to 20 carbon atoms, more preferably). Has 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy. An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl, pivaloyl, etc.), an alkoxycarbonyl group ( Preferably it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl and the like, and an aryloxycarbonyl group (preferably having a carbon number). 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl, etc.), acyloxy group (preferably 2 to 20 carbon atoms, more preferably carbon 2 to 16, particularly preferably 2 to 10 carbon atoms, such as acetoxy, benzoyloxy, etc. Is mentioned. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetylamino, benzoylamino, etc.), an alkoxycarbonylamino group (Preferably having 2 to 20 carbon atoms, more preferably having 2 to 16 carbon atoms, and particularly preferably having 2 to 12 carbon atoms, such as methoxycarbonylamino), an aryloxycarbonylamino group (preferably having a carbon number) 7 to 20, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, sulfonylamino group (preferably 1 to 20 carbon atoms, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino, And sulfamoyl groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethyl). Sulfamoyl, phenylsulfamoyl, etc.), a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl, methyl Carbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), alkylthio groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, ethylthio, etc. An arylthio group (preferably having 6 to 6 carbon atoms). 0, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and the like, a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms). Particularly preferably, it has 1 to 12 carbon atoms, such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 1 carbon atoms). 12 such as methanesulfinyl, benzenesulfinyl, etc.), a ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, for example, ureido , Methylureido, phenylureido, etc.), phosphoric acid amide groups (preferably having 1 to 20 carbon atoms, more preferably 1 to carbon atoms). 16, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide and phenyl phosphoric acid amide. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, etc., specifically, imidazolyl, pyridyl, quinolyl, And furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 carbon atoms). To 24, and examples thereof include trimethylsilyl and triphenylsilyl). .
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  Preferred as the general formula (101) is a compound represented by the following general formula (101-A).

(Wherein R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹⁰⁷ and R ¹⁰⁸ each independently represents a hydrogen atom or a substituent)

R ¹⁰¹ , R ¹⁰² , R ¹⁰³ , R ¹⁰⁴ , R ¹⁰⁵ , R ¹⁰⁶ , R ¹⁰⁷ , and R ¹⁰⁸ each independently represent a hydrogen atom or a substituent, and the substituent T described above can be applied as the substituent. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹⁰¹ and R ¹⁰³ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably an alkyl group having 1 to 12 carbon atoms (preferably 4 to 12 carbon atoms).

R ¹⁰² and R ¹⁰⁴ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a C1-12 alkyl group, particularly preferably a hydrogen atom and a methyl group, most preferably Is a hydrogen atom.

R ¹⁰⁵ and R ¹⁰⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and an alkyl group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom and a methyl group, most preferably It is a hydrogen atom.

R ¹⁰⁶ and R ¹⁰⁷ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, and a halogen atom, more preferably a hydrogen atom. An atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group, and a halogen atom, more preferably a hydrogen atom and a halogen atom, and particularly preferably a hydrogen atom and a chlorine atom.

  More preferable as the general formula (101) is a compound represented by the following general formula (101-B).

(In the formula, R ¹⁰¹ , R ¹⁰³ , R ¹⁰⁶ and R ¹⁰⁷ have the same meanings as those in formula (101-A), and preferred ranges are also the same).
Although the specific example of a compound represented by General formula (101) below is given, it is not limited to the following specific example.

  Among the above benzotriazole-based compounds, when a cellulose ester film is produced without including a molecular weight of 320 or less, it is advantageous in terms of retention.

  Moreover, as a benzophenone-type compound used as a wavelength dispersion regulator, what is shown by following General formula (102) is preferable.

(Wherein Q ¹¹¹ and Q ¹¹² each independently represents an aromatic ring. X ¹¹¹ represents NR ¹¹⁰ (R ¹¹⁰ represents a hydrogen atom or a substituent), an oxygen atom or a sulfur atom.)

The aromatic ring represented by Q ¹¹¹ and Q ¹¹² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.
The aromatic hydrocarbon ring represented by Q ¹¹¹ and Q ¹¹² is preferably (preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). More preferably an aromatic hydrocarbon ring having 6 to 20 carbon atoms, still more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms.) More preferably, it is a benzene ring.
The preferred aromatic heterocycle represented by Q ¹¹¹ and Q ¹¹² is an oxygen atom, nitrogen atom or at least one containing aromatic hetero ring one any of the sulfur atom. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, Examples include quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.
The aromatic ring represented by Q ¹¹¹ and Q ¹¹² is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, still more preferably a substituted or unsubstituted benzene ring. is there.
Q ¹¹¹ and Q ¹¹² may further have a substituent, and the above-described substituent T is preferable, but the substituent does not include a carboxylic acid, a sulfonic acid, or a quaternary ammonium salt. Further, if possible, substituents may be linked to form a ring structure.

X ¹¹¹ represents NR ¹¹⁰ (R ¹¹⁰ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied), an oxygen atom or a sulfur atom. When X ¹¹¹ is NR ¹¹⁰ , R ¹¹⁰ is preferably an acyl group or a sulfonyl group, and these substituents may be further substituted. X ¹¹¹ is preferably NR ¹¹⁰ or an oxygen atom, and particularly preferably an oxygen atom.

  As the substituent T, those similar to the general formula (101) can be used.

  As the general formula (102), a compound represented by the following general formula (102-A) is preferable.

(In the formula, R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , R ¹¹⁷ , R ¹¹⁸ and R ¹¹⁹ each independently represent a hydrogen atom or a substituent.)

R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , R ¹¹⁷ , R ¹¹⁸ and R ¹¹⁹ each independently represent a hydrogen atom or a substituent. Applicable. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ¹¹¹ , R ¹¹² , R ¹¹³ , R ¹¹⁴ , R ¹¹⁵ , R ¹¹⁶ , R ¹¹⁷ , R ¹¹⁸ and R ¹¹⁹ are preferably hydrogen atoms, alkyl groups, alkenyl groups, alkynyl groups, aryl groups, substituted or unsubstituted amino groups. Group, alkoxy group, aryloxy group, hydroxy group and halogen atom, more preferably hydrogen atom, alkyl group, aryl group, alkyloxy group, aryloxy group and halogen atom, still more preferably hydrogen atom, carbon 1 -12 alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ¹¹² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, and more preferably an alkoxy group having 1-20 carbon atoms. And particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ¹¹⁷ is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom or one carbon atom. An alkyl group having -20 carbon atoms, an amino group having 0-20 carbon atoms, an alkoxy group having 1-12 carbon atoms, an aryloxy group having 6-12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom, having 1-20 carbon atoms. An alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

  More preferable as the general formula (102) is a compound represented by the following general formula (102-B).

(Wherein R ¹²⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group.)

R ¹²⁰ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. Applicable.
R ¹²⁰ is preferably a substituted or unsubstituted alkyl group, more preferably a substituted or unsubstituted alkyl group having 5 to 20 carbon atoms, and still more preferably a substituted or unsubstituted alkyl group having 5 to 12 carbon atoms. (Including n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc.), particularly preferably a substitution of 6 to 12 carbon atoms or It is an unsubstituted alkyl group (2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group).

The compound represented by the general formula (102) can be synthesized by the method described in JP-A-11-12219.
Although the specific example of a compound represented by General formula (102) below is given, it is not limited to the following specific example.

  Moreover, as a compound containing the cyano group used as a wavelength dispersion regulator, what is shown by the following general formula (103) is preferable.

(In the formula, Q ¹²¹ and Q ¹²² each independently represent an aromatic ring. X ¹²¹ and X ¹²² represent a hydrogen atom or a substituent, and at least one of them represents a cyano group.)
The aromatic ring represented by Q ¹²¹ and Q ¹²² may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

  The aromatic hydrocarbon ring is preferably a monocyclic or bicyclic aromatic hydrocarbon ring having 6 to 30 carbon atoms (such as a benzene ring or a naphthalene ring), and more preferably having 6 to 20 carbon atoms. An aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms. More preferred is a benzene ring.

  The aromatic heterocycle is preferably an aromatic heterocycle containing a nitrogen atom or a sulfur atom. Specific examples of the heterocyclic ring include, for example, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, Examples include phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, and tetrazaindene. Preferred examples of the aromatic heterocycle include pyridine, triazine, and quinoline.

The aromatic ring represented by Q ¹²¹ and Q ¹²² is preferably an aromatic hydrocarbon ring, and more preferably a benzene ring.
Q ¹²¹ and Q ¹²² may further have a substituent, and the substituent T described later is preferable. The substituent T is the same as in the general formula (101).

X ¹²¹ and X ¹²² each represent a hydrogen atom or a substituent, and at least one of them represents a cyano group. The substituent T described above can be applied to the substituents represented by X ¹²¹ and X ¹²² .
In addition, the substituent represented by X ¹²¹ and X ¹²² may be further substituted with another substituent, and X ¹²¹ and X ¹²² may each be condensed to form a ring structure.

X ¹²¹ and X ¹²² are preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocycle, and more preferably a cyano group, a carbonyl group, a sulfonyl group, An aromatic heterocycle, more preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group (—C (═O) OR ′ (R ′ is a C 1-20 alkyl group, carbon A number 6 to 12 aryl group and a combination thereof)).

  As the general formula (103), a compound represented by the following general formula (103-A) is preferable.

(Wherein R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ , R ¹²⁹ and R ¹³⁰ each independently represents a hydrogen atom or a substituent. X ¹²¹ and X ¹²² is synonymous with those in formula (103), and the preferred range is also the same.)

R ¹²¹ , R ¹²² , R ¹²³ , R ¹²⁴ , R ¹²⁵ , R ¹²⁶ , R ¹²⁷ , R ¹²⁸ , R ¹²⁹ and R ¹³⁰ each independently represents a hydrogen atom or a substituent, and the substituent T Is applicable. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

^R121 , ^R122 , ^R123 , ^R124 , ^R125 , ^R126 , ^R127 , ^R128 , ^R129 and ^R130 are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, substituted or unsubstituted Substituted amino group, alkoxy group, aryloxy group, hydroxy group and halogen atom, more preferably hydrogen atom, alkyl group, aryl group, alkyloxy group, aryloxy group and halogen atom, more preferably hydrogen atom , A carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ¹²³ and R ¹²⁸ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, a halogen atom, more preferably a hydrogen atom, An alkyl group having 1 to 20 carbon atoms, an amino group having 0 to 20 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, and a hydroxy group, more preferably a hydrogen atom and 1 carbon atom. An alkyl group having 12 to 12 carbon atoms and an alkoxy group having 1 to 12 carbon atoms, particularly preferably a hydrogen atom.

  More preferable as the general formula (103) is a compound represented by the following general formula (103-B).

(Wherein R ¹²³ and R ¹²⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. X ¹²³ represents a hydrogen atom or a substituent.)

X ¹²³ represents a hydrogen atom or a substituent. As the substituent, the above-described substituent T can be applied, and if possible, the substituent may be further substituted with another substituent. X ¹²³ is preferably a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, a carbonyl group, a sulfonyl group, or an aromatic heterocyclic ring, and more preferably a cyano group, a carbonyl group, a sulfonyl group, or an aromatic heterocyclic ring. More preferably a cyano group or a carbonyl group, and particularly preferably a cyano group or an alkoxycarbonyl group —C (═O) OR ″ (R ″ is: an alkyl group having 1 to 20 carbon atoms and an alkyl group having 6 to 12 carbon atoms. Aryl groups and combinations thereof).

  More preferable as the general formula (103) is a compound represented by the general formula (103-C).

(Wherein R ¹²³ and R ¹²⁸ have the same meanings as those in formula (103-A), and preferred ranges are also the same. R ¹³¹ represents an alkyl group having 1 to 20 carbon atoms.)

R ¹³¹ is preferably an alkyl group having 2 to 12 carbon atoms, more preferably an alkyl group having 4 to 12 carbon atoms, and still more preferably when both R ¹²³ and R ¹²⁸ are hydrogen atoms. , An alkyl group having 6 to 12 carbon atoms, particularly preferably an n-octyl group, a tert-octyl group, a 2-ethylhexyl group, an n-decyl group, or an n-dodecyl group, most preferably 2- An ethylhexyl group.

As R ¹³¹ , preferably, when R ¹²³ and R ¹²⁸ are other than hydrogen, the compound represented by the general formula (103-C) has a molecular weight of 300 or more and an alkyl group having 20 or less carbon atoms. Is preferred.

  The compound represented by the general formula (103) can be synthesized by the method described in Journal of American Chemical Society 63, 3452 (1941).

  Although the specific example of a compound represented by General formula (103) below is given, it is not limited to the following specific example.

<Film properties>
[Film flatness]
As for the surface of the cellulose ester film of this invention, it is preferable that the maximum height (Ry) of the surface unevenness | corrugation of this film | membrane based on JISB0601-1994 is 0.5 micrometer or less. More preferably, it is 0.3 micrometer or less, More preferably, it is 0.2 micrometer or less. The concave and convex shapes on the film surface can be evaluated by an atomic force microscope (AFM).
Further, the arithmetic average roughness (Ra) of the surface irregularities of the film based on JIS B0601-1994 is preferably 0.1 μm or less, and more preferably 0.05 μm or less.
The cellulose ester film of the present invention is composed of a cellulose ester derived from a cotton linter having a quotient of 6% viscosity of 1.2 or more and a cellulose ester derived from wood pulp. It is presumed that the unevenness of the was made small.

[Retention of film]
In the cellulose ester film of the present invention, it is preferable that the retention of various compounds added to the film is high. Specifically, after adjusting the cellulose ester film of the present invention for 20 hours at 80 ° C. and 90% RH after humidity conditioning at 25 ° C. and 50% RH for 4 hours, the mass change of the film is 2.0%. The following is preferable. More preferably, it is 0-1.5%, More preferably, it is 0-1.0%.
The cellulose ester film of the present invention comprises a cellulose ester derived from a cotton linter having a quotient of 6% viscosity of 1.2 or more and a cellulose ester derived from wood pulp, thereby forming a unique internal structure and dissolving with a compound. It is presumed that the retention was increased and the retention was increased.
<Reservation evaluation method>
The sample was cut to a size of 10 cm × 10 cm, and the mass after being left for 4 hours in an atmosphere of 25 ° C. and 50% RH (referred to as the mass before treatment) was measured, and 80 ± 5 ° C. and 90 ± 10% RH Leave for 20 hours under the conditions of This is repeated 10 times, the surface of the treated sample is lightly wiped, the mass after standing for 1 day at 25 ° C. and 50% RH (referred to as the mass after treatment) is measured, and the retention property is calculated by the following method. did.
Retention property (mass%) = {(mass before treatment−mass after treatment) / mass before treatment} × 100

[Transparency of film]
The cellulose ester film of the present invention preferably has high transparency, and preferably has a total light transmittance of 80% or more, more preferably 90% or more.

[Curl characteristics of film]
The curl value of the cellulose ester film of the present invention is -21 to + 21 / m in both the MD direction and the TD direction in the entire range of temperature and humidity conditions of 25 ° C. and 10% RH to 25 ° C. and 80% RH. More preferably, it is −15 / m to + 15 / m, still more preferably −10 / m to + 10 / m, and particularly preferably −5 / m to + 5 / m.

The curl of the cellulose ester film of the present invention is preferably not changed by temperature and humidity, the MD direction of the curl in the curl value in the MD direction C _{MD, 80} and under RH 25 ° 10% under RH 25 ° 80% value C _MD, it is preferred that the difference between _{10 (C MD, 80 -C MD} , 10) is -14 / m~ + 14 / m, and the curl value in the TD direction under RH 25 ° 80% C _TD, it is preferable ₈₀ the difference between the TD direction curl value _{C TD, 10} of the under RH 25 ° _{10% (C TD, 80 -C} TD, 10) is -14 / m~ + 14 / m. More _{preferably, (C MD, 80 -C MD} , 10) and _{(C TD, 80 -C TD,} 10) is the -11 / m~11 / m, more preferably -7 / m~ + 7 / m And is particularly preferably −5 / m to + 5 / m.

  Furthermore, the difference between the curl value at 25 ° C. and 10% RH and the curl value at 45 ° C. and 10% RH is preferably −19 / m to + 19 / m in both the MD and TD directions. More preferably, it is −14 / m to + 14 / m, and particularly preferably −9 / m to + 9 / m. Furthermore, the difference between the curl value at 25 ° C 60% RH and the curl value at 45 ° C 60% RH, and the difference between the curl value at 25 ° C 80% RH and the curl value at 45 ° C 80% RH, MD and Both in the TD direction are preferably −19 / m to + 19 / m. More preferably, it is −14 / m to + 14 / m, and particularly preferably −9 / m to + 9 / m.

  The cellulose ester film of the present invention comprises a cellulose ester derived from a cotton linter having a quotient of 6% viscosity of 1.2 or more and a cellulose ester derived from wood pulp, thereby forming a unique internal structure, It is presumed that since the solubility with the compound increased, the additive distribution in the film became uniform in the thickness direction and the curl value decreased.

When the cellulose ester film of the present invention is used as a polarizing plate protective film and bonded to a polarizing film, particularly in the case of efficiently bonding a long polarizing film and a long cellulose ester film, The cellulose ester film of the present invention is used when performing surface treatment, rubbing treatment when applying an optically anisotropic layer, and applying optically anisotropic layers and various functional layers as long products. If the curl value is in the above-mentioned range, the film handling is not hindered and the trouble of cutting the film hardly occurs. In addition, the film does not come into strong contact with the transport roll at the edge or the center of the film, so it is difficult to generate dust, and there is little adhesion of foreign matter on the film. The frequency of point defects and coating stripes is within an allowable range. Furthermore, by setting the curl value within the above-mentioned range, it is possible to prevent bubbles from entering when the polarizing film is bonded, and it is possible to reduce color spot failures that are likely to occur when an optically anisotropic layer is installed.
The curl value can be measured according to a measurement method (ANSI / ASCPH1.29-1985) defined by the American National Standards Institute.

[Film thickness]
The thickness of the cellulose ester film of the present invention is preferably 30 to 120 μm, and the optical compensation film or the polarizing plate protective film is preferably 40 to 100 μm, more preferably 60 to 80 μm, and even more preferably 65 It is especially preferable that it is -75 micrometers.

[Equilibrium moisture content of film]
The equilibrium moisture content of the cellulose ester film of the present invention is such that when used as a protective film for a polarizing plate, the adhesiveness with a water-soluble polymer such as polyvinyl alcohol is not impaired. The equilibrium water content in RH is preferably 3.0% or less. It is more preferably 0.1 to 2.5%, and particularly preferably 1 to 2%. An equilibrium water content of 3% or less is preferable because the dependency of retardation on humidity change does not increase when used as a support for an optical compensation film.
The water content was measured by measuring the cellulose ester film sample 7 mm × 35 mm of the present invention by the Karl Fischer method using a moisture measuring device and a sample drying apparatus (CA-03, VA-05, both Mitsubishi Chemical Corporation). It can be calculated by dividing the amount of water (g) by the sample mass (g).

[Water permeability of film]
The moisture permeability of the cellulose ester film of the present invention is measured under the conditions of a temperature of 60 ° C. and a humidity of 95% RH based on JIS standard JISZ0208, and converted to a film thickness of 80 μm, 100 g / m ² · 24 h or more, 2000 g / m ² · 24h or less is preferable. More preferably 200~1200g / m ² · 24h, and particularly preferably 300~1000g / m ² · 24h. When it is 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 is less likely to exceed 0.3 nm /% RH. Also, when an optically anisotropic film is laminated on the cellulose ester film of the present invention to form an optical compensation film, the absolute value of the humidity dependence of the Re value and Rth value is less likely to exceed 0.3 nm /% RH. Therefore, it is preferable. When this optical compensation film or polarizing plate is incorporated in a liquid crystal display device, it is preferable from the viewpoint of color change and viewing angle. In addition, when the moisture permeability of the cellulose ester film is 100 g / m ² · 24 h or more, when the polarizing plate is produced by sticking to both surfaces of the polarizing film, drying of the adhesive is prevented by the cellulose ester film. There is no adhesion failure.

If the film thickness of the cellulose ester film is thick, the moisture permeability becomes small, and if the film thickness is thin, the moisture permeability becomes large. Therefore, it is necessary to convert the sample of any film thickness to a standard of 80 μm. The conversion of the film thickness can be obtained as (moisture permeability in terms of 80 μm = measured moisture permeability × measured film thickness μm / 80 μm).
The measurement method of moisture permeability is “Polymer Physical Properties II” (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation amount (mass method, thermometer method, vapor pressure method, adsorption amount method) The cellulose ester film sample 70 mmφ of the present invention was conditioned at 25 ° C., 90% RH, 60 ° C., and 95% RH for 24 hours, respectively, and a moisture permeation test apparatus (KK-709007, Toyo Seiki Co., Ltd.) can calculate the amount of water per unit area (g / m ² ) according to JIS Z-0208, and obtain moisture permeability = mass after humidity adjustment−mass before humidity adjustment.

  The moisture permeability of the cellulose ester film of the present invention can be controlled by appropriately adjusting the type of ester group of the cellulose ester, the ratio thereof, the degree of substitution, the type of additive, the amount thereof, and the like.

[Haze of film]
The haze of the cellulose ester film of the present invention is preferably 0.01 to 2.0%. More preferably, it is 0.05 to 1.5%, and more preferably 0.1 to 1.0%. As a transparent film, the transparency of the film is important. The haze can be measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH for the cellulose ester film sample 40 mm × 80 mm of the present invention.
The haze of the cellulose ester film of the present invention can be controlled by appropriately adjusting the additive type, its amount, and drying conditions.

<Film additives>
The cellulose ester film of the present invention can contain various additives, and the additive is not limited as long as it is an addition amount capable of setting the retardation in the film thickness direction to a desired range. For example, in addition to the above-described retardation reducing agent (compound that reduces optical anisotropy) and wavelength dispersion adjusting agent, other optical property adjusting agents, UV inhibitors, plasticizers, deterioration inhibitors, fine particles, and the like can be given. .
Various additives can be added at each stage of manufacture. The time to add is not specifically limited. It can be added to the preparation step of a polymer solution (hereinafter also referred to as a dope). In this case, a step of adding and preparing an additive may be added to the last step of the dope preparation step.

[Content of additive]
The cellulose ester film of the present invention preferably contains 0.3% by mass or more, for example, 0.3% by mass or more and 45% by mass or less of an additive of cellulose ester. The additive can adjust various film properties such as optical properties and physical properties of the resin material in a wider range than a film made of only the resin material. More preferably, it is 5-40 mass%, More preferably, it is 10-30 mass%. As described above, these compounds include a compound for reducing retardation, a wavelength dispersion adjusting agent, an ultraviolet ray preventing agent, a plasticizer, a deterioration preventing agent, a compound for forming a crosslinked structure, a cellulose ester compatible polymer, and a fine particle. The molecular weight is preferably 3000 or less, more preferably 2000 or less, and still more preferably 1000 or less. When the total amount of these compounds is 0.3% by mass or more, the properties of the base resin material alone are difficult to be obtained, and for example, the optical performance and physical strength are less likely to fluctuate with respect to changes in temperature and humidity. . Further, when the total amount of these compounds is 45% by mass or less, there is a problem that the compound does not exceed the limit of compatibility in the cellulose ester film, and the film is deposited on the film surface and the film becomes cloudy (crying out from the film). It is preferable because it is difficult to occur.

[Thickness direction distribution of additives]
The cellulose ester film of the present invention contains an additive of a compound having a molecular weight of 3000 or less with respect to the mass of the resin material constituting the cellulose ester film, 0.3% or more, and the cellulose ester film in the thickness direction. Of the eight regions excluding the outermost layer in the region divided into 10 equal to 80, the average additive present amount of the whole cellulose ester film (the value obtained by dividing the total additive amount in the film by 10) is 80. % To 120% is preferable. In this way, the uniform distribution of additives is considered to make it possible to bring the curl value of the cellulose ester film close to 0 at room temperature and normal humidity, low humidity, and high humidity, as well as at low and high temperatures. It is considered that the fluctuation of the curl due to the fluctuation of the temperature and the temperature change can be suppressed to be small. The amount of additive present in each region is more preferably 85% to 115% of the average amount of film present, and particularly preferably 90% to 110%.

The thickness direction distribution of the additive can be evaluated using TOF-SIMS IV (Au ₁ ⁺ as primary ions, 25 keV) manufactured by ION-TOF. The additive strength of each layer divided into 10 portions in the film thickness direction from the support surface at the time of film casting to the air surface (anti-support surface) is calculated and evaluated. When it has a plurality of additives, the addition strength is calculated for each additive, the amount of additive contained in the entire film is calculated, and the amount of additive in each layer can be evaluated according to the ratio.

[paint remover]
It is preferable to add a release agent to the resin material used in the present invention, such as a cellulose ester film, in order to reduce the load at the time of peeling.
As the release agent, it is effective to use a known surfactant. As this surfactant, surfactants of phosphoric acid type, sulfonic acid type, carboxylic acid type, nonionic type, cationic type and the like can be used and are not particularly limited. Examples of the surfactant that can be used here are described, for example, in JP-A-61-243837.

As for the release agent, Japanese Patent Application Laid-Open No. 2003-055501 discloses a cellulose acylate solution dissolved in a non-chlorine solvent in order to prevent white turbidity of the cellulose acylate solution and improve film production peelability and film surface shape. In addition, there is a description of a cellulose acylate solution containing an additive selected from a polybasic acid partial ester having an acid dissociation index pKA of 1.93 to 4.5, an alkali metal salt, and an alkaline earth metal salt.
Regarding the additive, Japanese Patent Application Laid-Open No. 2003-128838 discloses a cross-linking agent having two or more groups that react with at least one kind of active hydrogen in order to improve the stripping property, surface shape, and film strength. There exists description about the cellulose acylate dope solution which contains 0.1-10 mass% with respect to a cellulose acylate.
Japanese Patent Application Laid-Open No. 2003-165868 proposes a film having an additive added, having good moisture permeability and excellent dimensional stability.
In the present invention, the release agent described in the above publication can be used.
The preferable content of the release agent is 1% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less of the cellulose ester.

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose ester film of the present invention. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter 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 diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, 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 from 0.2 μm to 1.5 μm, more preferably from 0.4 μm to 1.2 μm, and most preferably from 0.6 μm to 1.1 μm. The primary and secondary particle sizes were determined by observing the particles in the film with a scanning electron microscope and determining the diameter of a circle circumscribing the particles 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 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

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

In order to obtain a cellulose ester film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a dispersion of fine particles. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are stirred and mixed in advance, adding the fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with the 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. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. 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 ester dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.16 g per 1 m ^2. preferable.

  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.

[Plasticizers, deterioration inhibitors]
In addition to the above-mentioned compounds that reduce retardation, wavelength dispersion adjusting agents, etc., the cellulose ester film of the present invention has various additives (for example, plasticizers, UV inhibitors, deterioration, etc.) in each preparation step. Inhibitors, infrared absorbers, etc.), which can be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing materials at 20 ° C. or lower and 20 ° C. or higher, and similarly mixing of a plasticizer is described in, for example, Japanese Patent Application Laid-Open No. 2001-151901. Furthermore, infrared absorbing dyes are described, for example, in JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation process, but may be added by adding an additive to the final preparation process of the dope preparation process. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose-ester film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, it is described in Japanese Patent Application Laid-Open No. 2001-151902, but these are conventionally known techniques. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.

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

[Method for producing cellulose ester film]
The production method of the present invention includes a step of casting a dope in which a cellulose ester is dissolved in a solvent, a step of peeling the film from the support, and a step of drying the peeled film.

(Preparation of cellulose ester solution)
A method for producing a film using a cellulose ester solution will be described. As the method and equipment for producing the cellulose ester 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 used.
The cellulose ester solution (dope) used in the production of the cellulose ester film of the present invention is a mixture of cellulose ester derived from cotton linter and cellulose ester derived from wood pulp separately dissolved in a dissolving machine (kettle), or , Put each cellulose ester in one dissolver (pot) charged with solvent in advance, mix and dissolve the dope once in the storage pot, and defoam the dope to make the final preparation can do. Moreover, you may make the dope contain the cellulose ester derived from other raw materials, such as kenaf, by the same method.
At this time, it can be adjusted by either a heating dissolution method or a cooling dissolution method, but it is necessary to sufficiently mix a cellulose ester derived from cotton linter and a cellulose ester solution derived from wood pulp.
As described above, the cellulose ester used as a raw material for the cellulose ester film of the present invention includes at least one cellulose derived from a cotton linter and at least one derived from a wood pulp as the cellulose ester raw material. Is included. Moreover, the cellulose ester derived from cotton linter, kenaf other than wood pulp, etc. can be included.
In the present invention, the content (also referred to as linter ratio) of the cellulose ester derived from the cotton linter in the total cellulose ester is 5% by mass or more and 90% by mass or less. That is, the ratio of linter / pulp (including kenaf) is 5% by mass / 95% by mass to 90% by mass / 10% by mass.
When the linter ratio is less than 5%, the peelability described later may deteriorate, which is not preferable. On the other hand, when the linter ratio exceeds 90%, the ratio of cellulose ester produced from inexpensive wood pulp is inevitably small, and the cost cannot be sufficiently reduced, which is not preferable.
The linter / pulp ratio is more preferably 10% by mass / 90% by mass to 75% by mass / 25% by mass, and further preferably 20% by mass / 80% by mass to 50% by mass / 50% by mass.
When preparing the dope, the concentration of the cellulose ester derived from each raw material is adjusted so that the linter ratio of the cellulose ester to be used falls within the above range.

The dope thus adjusted is fed from a dope outlet through a pressurized metering gear pump capable of delivering a metered amount with high accuracy by, for example, the number of revolutions, and a matting agent solution and a UV absorber prepared in advance before the casting die. A solution, a retardation adjusting agent solution, a wavelength dispersion adjusting agent, a release agent solution, a plasticizer solution, or the like is mixed in-line. These additive solutions may be mixed sequentially. Alternatively, some or all of them may be mixed in advance and then mixed with the cellulose ester solution.
It is also possible to add a part of the additive in advance to the dissolver and mix other additives in-line.

(Casting)
As a method of casting the solution on the support, the prepared dope is uniformly extruded onto the endless metal support from a pressure die, and the film thickness of the dope once cast on the metal support is increased with a blade. There are a method using a doctor blade for adjustment, a method using a reverse roll coater for adjustment using a reverse rotating roll, and the like, but a method using a pressure die is preferred. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various methods for casting a cellulose triacetate solution known in the art, and by setting each condition in consideration of differences in the boiling point of the solvent used, etc. The same effects as described in the above publication can be obtained. As the endlessly running metal support used for producing the cellulose ester film of the present invention, stainless steel whose surface is mirror-finished by chromium plating or whose surface roughness is finished to 0.05 μm or less by polishing is used. A plate endless band or drum is used. The surface temperature of the metal support is generally 0 to 35 ° C. Moreover, in the cooling gelation casting method, it is −50 to 0 ° C., preferably −35 to −3 ° C., and more preferably −25 to −5 ° C. One or two or more pressure dies used for producing the cellulose ester film of the present invention may be installed above the metal support. Preferably 1 or 2 groups.

  When two or more units are installed, the amount of dope to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose ester solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. A temperature 5 to 15 ° C. lower than the boiling point of the solvent used is preferred. The temperature of the cellulose ester solution may be the same at all locations in the process, or may be different at various locations in the process. If they are different, the temperature may be in the above range immediately before casting.

  The endless metal support preferably has a width of 0.8 to 2.5 m, a length of 5 to 120 m, and a thickness of 0.8 to 3.5 mm. The casting width is 40 cm to 2.3 m, and the moving speed of the metal support (that is, the casting speed) depends on the solid content concentration of the dope, the finished film thickness, the length of the endless metal support, the support temperature, etc. However, 0.5 to 300 m / min can be used.

  Further, JP-A No. 2001-129638, JP-A No. 2000-317960, JP-A No. 2000-301555, JP-A No. 2000-301558, JP-A No. 11-221833, JP-A No. 07-032391, JP-A No. 05-185445, JP 05-086212, JP 03-193316, JP 02-276607, JP 02-111511, JP 02-208650, JP 62-037113, JP 62-1115035, The techniques described in JP-A-55-014201 and JP-A-52-10362 can be applied in the present invention.

(Multilayer casting)
In this section, cellulose acylate is described as an example, but it can be applied to other cellulose esters.
A cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a support, for example, a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. Also good. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used, and this method is a preferable casting method in the cooling gelation casting method using a high viscosity solution. Furthermore, it is also a preferable aspect that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution. Alternatively, by using two casting ports, peeling the film formed on the metal support by the first casting port, and performing the second casting on the side that was in contact with the metal support surface, A film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acylate solution can be cast by simultaneously casting other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a high-concentration and high-viscosity cellulose acylate solution in order to obtain the required film thickness. In many cases, this causes a problem such as a fault or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also the use of a concentrated cellulose acylate solution can reduce the drying load and increase the film production speed. In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness. In the case of co-casting, the above-mentioned retardation adjusting agent, wavelength dispersion adjusting agent, matting agent, release agent, plasticizer, UV absorber, etc. are co-casting cellulose acylate solutions having different concentrations to form a laminated structure The cellulose acylate film can also be produced. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the types of retardation adjusting agent, wavelength dispersion adjusting agent, plasticizer, and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the low volatile retardation adjusting agent and wavelength dispersion adjusting agent for the skin layer. In addition, a plasticizer and / or an ultraviolet absorber may be included, and a retardation adjusting agent, a wavelength dispersion adjusting agent, a plasticizer, or an ultraviolet absorbing agent excellent in ultraviolet absorbing property may be added to the core layer. Moreover, it is also a preferable aspect that a release agent is contained only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling gelation casting method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer.

(Peeling)
The cellulose ester solution is cast on a smooth band or a drum as a support, for example, an endless metal support, and then gelled by, for example, drying or cooling, and then peeled off from the support.
The cellulose ester solution according to the present invention can be peeled off by using a solution in which a cellulose ester derived from cotton linter and a cellulose ester derived from wood pulp are mixed, so that peeling properties similar to cotton linter can be realized. Thereby, it is guessed that peeling resistance does not become high and leads to the favorable flatness of the manufactured film.

(Cooling gelation)
For the cooling gelation performed in the present invention, the use of the cooling gelation casting method as described in JP-A-62-115035 is preferable because the casting is fast and the productivity is excellent. In this method, it is preferable that the metal support is cooled to 0 ° C. or lower, and dried by applying a drying air having a temperature and an amount of air that does not increase the surface temperature of the support for 2 seconds or more. In this method, since the film is given self-holding property mainly due to an increase in viscosity by cooling or gelation by cooling, the film can be peeled even with a high residual solvent content. A preferable residual solvent content at the time of peeling is 80 to 300%, more preferably 150 to 280%. The preferable film temperature at the time of peeling is 0 to -50 ° C, more preferably -5 to -25 ° C. In this method, since the time for single-sided drying on the support can be shortened, the total drying time can be greatly shortened, and the effect of reducing cost and environmental load is great. In cooling gelation casting, a drum is often used as a metal support. By enclosing the cooling liquid in the drum, the cast liquid film can be effectively cooled and gelled. The preferred outer peripheral length of the drum is 2 to 20 m. A preferred casting speed is 0.5 to 300 m / min. A more preferable casting speed per 1 m of the drum outer peripheral length is 2 to 200 m per minute, and particularly preferably 5 to 150 m.

(Tenter drying)
When the film is peeled from the support, the film is usually pulled at a speed of 1.001 times to 1.4 times the speed of the support. As the tensile speed ratio increases, the casting direction elastic modulus of the film can be increased. The peeled film is stretched in the width direction while regulating the shrinkage of the film or holding the film at both ends by a width regulating device (for example, a tenter device) as described in JP-A-62-115035. However, it is preferable to dry. The ratio of the film width at the entrance and exit of the width regulating device is preferably 0.75 to 1.4. It is preferable to stretch the film in the width direction because the elastic modulus in the width direction can be increased. Drying is preferably performed by blowing hot air of 40 to 150 ° C. It is preferable to divide the width regulating device into a plurality of parts and sequentially change the temperature of the drying air from the lower side to the higher side.

(After drying and winding)
After the residual solvent content in the film becomes 20% or less, the film is preferably removed from the width regulating device and further dried at a temperature of 100 to 150 ° C. It is preferable that both ears deformed by the width regulating device are cut off, and knurled at both ends to be wound up. The width of the knurling 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. This may be a single push or a double push. The winding length is preferably 100 to 10000 m, more preferably 500 to 6000 m, and still more preferably 1000 to 4000 m per roll.

(Polarizer)
The polarizing plate includes a polarizer and two transparent protective films disposed on both sides thereof. As the transparent protective film, the cellulose ester film of the present invention can be used. The cellulose ester film of the present invention may be used on both sides of the polarizer, or may be used only on one side. Examples of the polarizer include an iodine polarizer, a dye polarizer using a dichroic dye, and a polyene polarizer. The iodine polarizer and the dye polarizer are generally produced using a polyvinyl alcohol film. When using the cellulose-ester film of this invention as a polarizing plate protective film, the preparation methods of a polarizing plate are not specifically limited, It can produce by a general method. There is a method in which the obtained cellulose ester film is treated with an alkali and bonded to both surfaces of a polarizer 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 polarizer 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 polarizer and a protective film that protects both surfaces of the polarizer, and further comprises a protective film bonded to one surface of the polarizing plate and a separate film bonded to the other 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.

  The method of bonding the cellulose ester film of the present invention to the polarizer is not particularly limited in the bonding angle with the optical axis of the polarizer. The slow axis of the cellulose ester film and the transmission axis of the polarizer may be parallel, orthogonal, or an appropriate angle in between.

In the polarizing plate of the present invention, the single plate transmittance TT, parallel transmittance PT, orthogonal transmittance CT, and polarization degree P at 25 ° C. and 60% RH satisfy at least one of the following formulas (A) to (D). Is preferred.
(A) 40.0 ≦ TT ≦ 45.0
(B) 30.0 ≦ PT ≦ 40.0
(C) CT ≦ 2.0
(D) 95.0 ≦ P

The single plate transmittance TT, the parallel transmittance PT, and the orthogonal transmittance CT are more preferably 40.5 ≦ TT ≦ 45, 32 ≦ PT ≦ 39.5, and CT ≦ 1.5, respectively, in this order. Preferably, 41.0 ≦ TT ≦ 44.5, 34 ≦ PT ≦ 39.0, and CT ≦ 1.3. The degree of polarization P is preferably 95.0% or more, more preferably 96.0% or more, and further preferably 97.0% or more.
In the polarizing plate of the present invention, CT ₍₃₈₀₎ , CT ₍₄₁₀₎ , CT ₍₇₀₀₎ is at least one of the following formulas (E) to (G) when the orthogonal transmittance at wavelength λ is CT _(λ). It is preferable to satisfy one or more.
(E) CT ₍₃₈₀₎ ≦ 2.0
(F) CT ₍₄₁₀₎ ≦ 1.0
(G) CT ₍₇₀₀₎ ≦ 0.5

More preferably, CT ₍₃₈₀₎ ≤1.95, CT ₍₄₁₀₎ ≤0.9, CT ₍₇₀₀₎ ≤0.49, and more preferably CT ₍₃₈₀₎ ≤1.90, CT ₍₄₁₀₎ ≤0. .8, CT ₍₇₀₀₎ ≦ 0.48.

  The polarizing plate of the present invention has an orthogonal transmittance change ΔCT and a polarization degree change ΔP of at least one of the following formulas (J) and (K) when left at 60 ° C. and 95% RH for 500 hours. It is preferable to satisfy the above.

(J) −6.0 ≦ ΔCT ≦ 6.0
(K) -10.0 ≦ ΔP ≦ 0.0
(However, the amount of change indicates the value obtained by subtracting the measured value before the test from the measured value after the test.)
More preferably, −5.8 ≦ ΔCT ≦ 5.8, −9.5 ≦ ΔP ≦ 0.0, and still more preferably, −5.6 ≦ ΔCT ≦ 5.6, −9.0 ≦ ΔP ≦ 0.0. It is.
The polarizing plate of the present invention has at least one of the following formulas (H) and (i) having an orthogonal transmittance change ΔCT and a polarization degree change ΔP when left at 60 ° C. and 90% RH for 500 hours. It is preferable to satisfy the above.
(H) −3.0 ≦ ΔCT ≦ 3.0
(I) −5.0 ≦ ΔP ≦ 0.0

In the polarizing plate of the present invention, the change amount ΔCT of the orthogonal transmittance and the change amount ΔP of the polarization degree satisfy at least one of the following formulas (L) and (M) when left standing at 80 ° C. for 500 hours. It is preferable.
(L) −3.0 ≦ ΔCT ≦ 3.0
(M) −2.0 ≦ ΔP ≦ 0.0

The single plate transmittance TT, parallel transmittance PT, and orthogonal transmittance CT of the polarizing plate were measured in the range of 380 nm to 780 nm using UV3100PC (manufactured by Shimadzu Corporation), and TT, PT, CT were measured 10 times. An average value (average value between 400 nm and 700 nm) is used. The degree of polarization P can be determined by the degree of polarization (%) = 100 × {(parallel transmittance−orthogonal transmittance) / (parallel transmittance + orthogonal transmittance)} ^1/2 . The polarizing plate durability test is carried out as follows in two forms of (1) only the polarizing plate and (2) the polarizing plate attached to glass with an adhesive. For the measurement of only the polarizing plate, two orthogonal and the same materials are prepared and measured so that the cellulose ester film of the present invention is sandwiched between two polarizers. Two samples (about 5 cm × 5 cm) in which the polarizing plate is attached on the glass so that the cellulose ester film of the present invention is on the glass side are prepared on the glass attached state. In single-plate transmittance measurement, the sample is set with the film side facing the light source. Each of the two samples is measured, and the average value is taken as the transmittance of the single plate.

[Application (Optical compensation film)]
The cellulose ester film of the present invention can be used in various applications, and is particularly effective when used as an optical compensation film for a liquid crystal display device. The optical compensation 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 a retardation plate, an optical compensation sheet, and the like. Each of the optical compensation films has characteristic birefringence characteristics, and is used for the purpose of removing the color of the display screen of the liquid crystal display device or improving the viewing angle characteristics.
Since the cellulose ester film of the present invention has small optical anisotropy and small wavelength dispersion, it does not cause extra anisotropy and can be regarded as an optical compensation film having zero birefringence. By coating and providing an optically anisotropic layer having birefringence on the ester film, only the optical performance of the optically anisotropic layer can be expressed, and it can be used as a substrate for an optical compensation film.
Such an optical compensation film can also be used as a protective film for the polarizing plate described above.

Therefore, when the cellulose ester film of the present invention is used as an optical compensation film of a liquid crystal display device, Re and Rth of the optically anisotropic layer used together are Re ₍₅₉₀₎ = 0 to 200 nm and | Rth ₍₅₉₀₎ | = 0 to 400 nm. In this range, any optically anisotropic layer may be used. The optical performance and driving method of the liquid crystal cell of the liquid crystal display device in which the cellulose ester film of the present invention is used are not limited, and any optical anisotropic layer required as an optical compensation film can be used in combination. The optically anisotropic layer used in combination may be formed from a composition containing a liquid crystalline compound or may be formed from a polymer film having birefringence.

  The liquid crystal compound is preferably a discotic liquid crystal compound or a rod-like liquid crystal compound.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds that can be used in the present invention include various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, p. 111 (1981); Chemical Society of Japan). Ed., Quarterly Chemistry Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., P. 1985); J. Zhang et al., J. Am.Chem.Soc., Vol.116, p.2655 (1994)).

  In the optically anisotropic layer, the discotic liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284. In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. JP-A-2001-4387 discloses a discotic liquid crystalline molecule having a polymerizable group.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, and cyano-substituted compounds. Phenyl pyrimidines, alkoxy substituted phenyl pyrimidines, phenyl dioxanes, tolanes and alkenyl cyclohexyl benzonitriles are included. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used.

  In the optically anisotropic layer, the rod-like liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Examples of polymerizable rod-like liquid crystalline compounds that can be used in the present invention include Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, World Patents (WO) 95/22586, 95/24455. No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and JP-A-2001-2001. And the compounds described in US Pat.

(Optically anisotropic layer made of polymer film)
As described above, the optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer that can exhibit optical anisotropy. Examples of such polymers include polyolefins (eg, polyethylene, polypropylene, norbornene-based polymers), polycarbonates, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylates, polyacrylates and cellulose esters (eg, cellulose triacetate, Cellulose diacetate). Further, a copolymer or a polymer mixture of these polymers may be used.

  The optical anisotropy of the polymer film is preferably obtained by stretching. The stretching is preferably uniaxial stretching or biaxial stretching. Specifically, longitudinal uniaxial stretching using a difference in peripheral speed between two or more rolls, tenter stretching for grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching in combination of these is preferable. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 500 μm, and most preferably 40 to 100 μm.

(Liquid crystal display device)
The cellulose ester film, optical compensation film, and polarizing plate of the present invention can be suitably used for a liquid crystal display device.

(Configuration example of liquid crystal display device)
When the cellulose ester film is used as an optical compensation film, the transmission axis of the polarizing element and the slow axis of the optical compensation film made of the cellulose ester film 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 elements disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing element. 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 generally has a thickness of 50 μm to 2 mm.

(Types of liquid crystal display devices)
The cellulose ester film of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically Charged STP). Various display modes such as ECB (Electrically Controlled Birefringence) and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The cellulose ester film of the present invention is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

(TN type liquid crystal display device)
You may use the cellulose-ester film of this invention as a support body or polarizing plate protective film of the optical compensation sheet | seat of a TN type | mold liquid crystal display device which has 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 is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Also, in Mori et al. (Jpn. J. Appl. Phys., Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys., Vol. 36 (1997) p. 1068). There is a description.

(STN type liquid crystal display)
You may use the cellulose-ester film of this invention as a support body or polarizing plate protective film 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 for the STN type liquid crystal display device is described in JP-A-2000-105316.

(VA type liquid crystal display device)
The cellulose ester film of the present invention is particularly advantageously used as a support for an optical compensation sheet or a polarizing plate protective film of a VA liquid crystal display device having a VA mode liquid crystal cell. It is preferable that the Re retardation value of the optical compensation sheet used in the VA liquid crystal display device is 0 to 150 nm and the Rth retardation value is 70 to 400 nm. The Re retardation value is more preferably 20 to 70 nm. When two optically anisotropic polymer films are used in the VA liquid crystal display device, the Rth retardation 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 retardation 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 cellulose ester film of the present invention is particularly 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 parallel to the substrate surface in the absence of voltage. In these embodiments, the polarizing plate using the cellulose ester film of the present invention contributes to widening the viewing angle and improving the contrast. In this aspect, the retardation value of the optically anisotropic layer disposed between the protective film of the polarizing plate and the protective film and the liquid crystal cell is the value of Δn · d (refractive index difference × thickness) of the liquid crystal layer. It is preferable to set it to 2 times or less. In addition, since the absolute value | Rth | of the Rth value is preferably set to 25 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less, the cellulose ester film of the present invention is advantageously used.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The cellulose ester film of the present invention is also advantageously used as an optical compensation sheet support or polarizing plate protective film 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. It is done. 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 retardation 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 optically anisotropic layer, the optical properties of the support, and the optically 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 is described in JP-A-9-197397. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The cellulose ester film of the present invention is also advantageously used as a support for an optical compensation sheet or a polarizing plate protective film of a TN type, STN type, HAN type, or GH (Guest-Host) type reflective liquid crystal display device. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. The optical compensation sheet used in the reflective liquid crystal display device is described in WO00-65384.

(Other liquid crystal display devices)
The cellulose ester film of the present invention is also advantageously used as a support for an optical compensation sheet or a polarizing plate protective film of an ASM type liquid crystal display device having a liquid crystal cell of 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 are described in a paper by Kume et al. (Kume et al., SID98 Digest, 1089 (1998)).

(Hard coat film, antiglare film, antireflection film)
The cellulose ester film of the present invention can be preferably applied to 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 provided on one or both sides of the cellulose ester film of the present invention. can do. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). The cellulose ester film of the present invention can also be preferably used.

  The present invention will be described in detail based on examples, but the present invention is not limited thereto.

The characteristic evaluation of the cellulose ester film of the present invention was carried out as follows.
The evaluation of the in-plane retardation value Re and the retardation value Rth in the film thickness direction was measured by cutting a sample every nine points in the film width direction and every 100 m in the longitudinal direction, and the variation was displayed with standard deviation. A 30 mm × 40 mm sample was conditioned at 25 ° C. and 60% RH for 2 hours, and measured by the method described in the specification using an automatic birefringence meter KOBRA 21ADH (manufactured by Oji Scientific Instruments). The measurement wavelength was 590 nm.

  For the evaluation of flatness, the maximum height (Ry) of the surface irregularities of the film based on JIS B0601-1994 was evaluated by an atomic force microscope (AFM).

Evaluation of the retentivity was performed by cutting a sample into a size of 10 cm × 10 cm, measuring a mass after being left for 4 hours in an atmosphere of 25 ° C. and 50% RH (referred to as a mass before treatment), and 80 ± 5 ° C. And left for 20 hours under the condition of 90 ± 10% RH. This is repeated 10 times, the surface of the treated sample is lightly wiped, the mass after standing for 1 day at 25 ° C. and 50% RH (referred to as the mass after treatment) is measured, and the retention property is calculated by the following method. did.
Retention property (mass%) = {(mass before treatment−mass after treatment) / mass before treatment} × 100

[Example 1]
(Preparation of cellulose acylate solution)
The following composition was put into a mixing tank and stirred to dissolve each component. This solution was sent to a heat exchanger with a gear pump, kept at a temperature of 90 to 95 ° C. for 10 minutes, and then cooled to 30 ° C. with a cooling heat exchanger. This solution was filtered through a filter paper having an average pore size of 47 μm. The progress of clogging was slow. Furthermore, it filtered with the metal mesh filter of the hole diameter of 10 micrometers, and prepared the cellulose acetate solution (LA1). Here, cellulose acylates AR1 and AP1 were prepared by adjusting the aging time based on the method described in Example 2 and Example 1 of JP-A-2003-20131.

<Composition of cellulose acetate solution (LA1)>
Cellulose acylate (derived from cotton linter, acyl substitution degree: 2.93, 6% viscosity 364 mPa · s: AR1) 30 parts by mass Cellulose acylate (derived from wood pulp, acyl substitution degree: 2.91, 6% viscosity 243 mPa · s) : AP1) 70 parts by mass Methylene chloride 433 parts by mass Ethanol 75 parts by mass Reducing retardation (A-19) 12 parts by mass Citric acid ethyl ester 0.003 parts by mass

(Preparation of matting agent solution)
20 parts by mass of silica particles having an average particle diameter of 16 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) and 80 parts by mass of methanol were mixed well for 30 minutes to obtain a silica particle dispersion. This dispersion was put into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component, and filtered through a nonwoven fabric filter having an average pore size of 20 μm to prepare a matting agent solution (LC1).

<Composition of matting agent solution (LC1)>
Silica particle dispersion having an average particle size of 16 nm 12.0 parts by mass Methylene chloride 68.5 parts by mass Ethanol 11.8 parts by mass Cellulose acylate solution (LA1) 11.3 parts by mass

(Preparation of additive solution)
A liquid having the following composition was prepared and filtered through a filter paper having an average pore diameter of 47 μm to prepare an additive solution (LD1).

<Additive solution (LD1) composition>
Wavelength dispersion adjusting agent (UV-102) 7.3 parts by mass Methylene chloride 55.3 parts by mass Ethanol 9.5 parts by mass Cellulose acylate solution (LA1) 12.8 parts by mass

(Preparation of cellulose ester film (F1) of the present invention)
The cellulose acylate solution (LA1) 76.2 parts by mass, the matting agent solution (LC1) 1.8 parts by mass and the additive solution (LD1) 2.6 parts by mass were mixed with a static mixer, respectively, and the surface temperature was 20 ° C. Were cast uniformly on a stainless steel band. After drying until the residual solvent content was 60 to 80%, the film was peeled off from the stainless steel band at a speed of 45 m / min, and the film was fixed to a tenter device. At this time, the transport speed of the tenter was 1.02 times that of the band speed. The drying temperature in the tenter apparatus was changed from 70 ° C to 130 ° C stepwise. The film width at the exit was set to 1.01 times the film width at the entrance of the tenter device. After leaving the tenter device, it was further dried at 130 to 140 ° C. and wound up at a rate of 47 / min. In this way, a cellulose ester film (F1) having a film thickness of 81 μm was obtained. The residual solvent amount at the time of winding was 0.04%. The Ry (maximum height of surface irregularities) of the film was 0.2 μm. Re ₍₅₉₀₎ was 1.0 ± 0.8 nm and Rth ₍₅₉₀₎ was −5 ± 2 nm. Retention was 0.9%.

[Example 2]
(Preparation of cellulose ester film (F2) of the present invention)
76.2 parts by mass of the cellulose acylate solution (LA1) prepared in Example 1, 1.6 parts by mass of the matting agent solution (LC1), and 2.3 parts by mass of the additive solution (LD1) were mixed with a static mixer. And uniformly cast on a stainless steel drum cooled to -15 ° C. After cooling until the liquid temperature reached about −10 ° C., the film was peeled off from the drum at 60 m / min, and the film was fixed to a tenter device. At this time, the transport speed of the tenter was 1.06 times that of the drum speed. The drying temperature in the tenter apparatus was changed from 70 ° C to 130 ° C stepwise. The film width at the exit was 1.05 times the film width at the entrance of the tenter device. After leaving the tenter apparatus, the film was further dried at 130 to 140 ° C. and wound up at a speed of 65 m / min. Thus, the cellulose ester film (F2) of the present invention having a film thickness of 82 μm was obtained. The residual solvent amount at the time of winding was 0.03%. The Ry of the film was 0.2 μm. Re ₍₅₉₀₎ was 0.5 ± 0.3 nm and Rth ₍₅₉₀₎ was −7 ± 3 nm.

[Example 3]
(Preparation of cellulose acylate solution)
When a cellulose acylate solution was prepared in the same manner as in Example 1 using the following composition, it could be dissolved and filtered without problems.

<Composition of cellulose acetate solution (LA2)>
Cellulose acylate (derived from cotton linter, acyl substitution degree: 2.93, 6% viscosity 364 mPa · s: AR1) 60 parts by weight Cellulose acylate (derived from wood pulp, acyl substitution degree: 2.91, 6% viscosity 243 mPa · s) : AP1) 40 parts by mass Methylene chloride 438 parts by mass Methanol 70 parts by mass 1-butanol 4 parts by mass Reducing retardation (A-19) 12 parts by mass

(Preparation of matting agent solution)
A matting agent solution (LC2) was prepared in the same manner as in Example 1 except that the dispersion composition was changed to the following.

<Composition of matting agent solution (LC2)>
Silica particle dispersion having an average particle size of 16 nm 12.0 parts by mass Methylene chloride 76.6 parts by mass Methanol 3.7 parts by mass 1-butanol 0.8 parts by mass Cellulose acylate solution (LA2) 11.3 parts by mass

(Preparation of additive solution)
A liquid having the following composition was prepared and filtered through a filter paper having an average pore diameter of 47 μm to prepare an additive solution (LD2).

<Additive solution (LD2) composition>
Wavelength dispersion adjusting agent (UV-102) 7.3 parts by mass Methylene chloride 55.2 parts by mass Methanol 9.6 parts by mass 1-butanol 0.6 parts by mass Cellulose acylate solution (LA2) 12.8 parts by mass

(Preparation of cellulose ester film (F3) of the present invention)
In the same manner as in Example 1, the cellulose ester film F3 of the present invention was obtained from the cellulose acylate solution (LA2), the matting agent solution (LC2), and the additive solution (LD2). The film thickness was 65 μm, and the residual solvent amount at the time of winding was 0.2%. The Ry of the film was 0.3 μm. Re ₍₅₉₀₎ was 0.8 ± 0.4 nm and Rth ₍₅₉₀₎ was −2 ± 3 nm.

[Example 4]
(Preparation of cellulose ester film (F4) of the present invention)
The cellulose ester film of the example having a film thickness of 64 μm (like the example 2) except that the cellulose acylate solution (LA2), the matting agent solution (LC2) and the additive solution (LD2) prepared in Example 3 were used. F4) was obtained. The residual solvent amount at the time of winding was 0.4%. The Ry of the film was 0.3 μm. Re ₍₅₉₀₎ was 0.2 ± 0.7 nm and Rth ₍₅₉₀₎ was −2 ± 2 nm.

[Example 5]
(Preparation of cellulose acylate solution)
When a cellulose acylate solution was prepared in the same manner as in Example 1 using the following composition, it could be dissolved, filtered and concentrated without problems.

<Composition of cellulose acetate solution (LA3)>
Cellulose acylate (derived from cotton linter, acyl substitution degree: 2.93, 6% viscosity 364 mPa · s: AR1) 80 parts by weight Cellulose acylate (derived from wood pulp, acyl substitution degree: 2.91, 6% viscosity 243 mPa · s) : AP1) 20 parts by mass Methylene chloride 391 parts by mass Methanol 70 parts by mass 1-butanol 15 parts by mass Compound (A-19) for reducing retardation 12 parts by mass

(Preparation of matting agent solution)
A matting agent solution (LC3) was prepared in the same manner as in Example 1 except that the dispersion composition was changed to the following.

<Composition of matting agent solution (LC3)>
Silica particle dispersion having an average particle size of 16 nm 12.0 parts by mass Methylene chloride 67.3 parts by mass Methanol 12.0 parts by mass 1-butanol 2.4 parts by mass Cellulose acylate solution (LA3) 11.3 parts by mass

(Preparation of additive solution)
A liquid having the following composition was prepared and filtered through a filter paper having an average pore diameter of 47 μm to prepare an additive solution (LD3).

<Additive solution (LD3) composition>
Wavelength dispersion adjusting agent (UV-102) 7.3 parts by mass Methylene chloride 53.8 parts by mass Methanol 9.7 parts by mass 1-butanol 2.0 parts by mass Cellulose acylate solution (LA3) 12.8 parts by mass

(Preparation of cellulose ester film (F5) of the present invention)
In the same manner as in Example 1, the cellulose ester film (F5) of the present invention was obtained from the cellulose acylate solution (LA3), the matting agent solution (LC3), and the additive solution (LD3). The film thickness was 39 μm, and the residual solvent amount at the time of winding was 0.4%. The Ry of the film was 0.5 μm. Re ₍₅₉₀₎ was 1.3 ± 0.8 nm and Rth ₍₅₉₀₎ was −9 ± 9 nm.

[Example 6]
(Preparation of cellulose ester film (F6) of the present invention)
The cellulose ester film of the example having a film thickness of 44 μm was prepared in the same manner as in Example 2 except that the cellulose acylate solution (LA3), the matting agent solution (LC3) and the additive solution (LD3) prepared in Example 5 were used. F6) was obtained. The residual solvent amount at the time of winding was 0.4%. The Ry of the film was 0.4 μm. Re ₍₅₉₀₎ was 2.1 ± 0.9 nm and Rth ₍₅₉₀₎ was 6 ± 8 nm.

[Example 7]
(Preparation of cellulose acylate solution)
When a cellulose acylate solution was prepared in the same manner as in Example 1 using the following composition, it could be dissolved and filtered without problems. Here, cellulose acylates AR2 and AP2 were prepared by adjusting aging conditions such as aging time and aging temperature based on the methods described in Example 2 and Example 1 of JP-A-2003-20131.

<Composition of cellulose acetate solution (LA4)>
Cellulose acylate (derived from cotton linter, acyl substitution degree: 2.86, 6% viscosity 856 mPa · s: AR2) 80 parts by weight Cellulose acylate (derived from wood pulp, acyl substitution degree: 2.89, 6% viscosity 191 mPa · s) : AP2) 20 parts by mass Methylene chloride 391 parts by mass Methanol 70 parts by mass 1-butanol 15 parts by mass Compound (A-19) for reducing retardation 12 parts by mass

(Preparation of matting agent solution)
A matting agent solution (LC4) was prepared in the same manner as in Example 1 except that the dispersion composition was changed to the following.
<Composition of matting agent solution (LC4)>
Silica particle dispersion having an average particle size of 16 nm 12.0 parts by mass Methylene chloride 67.3 parts by mass Methanol 12.0 parts by mass 1-butanol 2.4 parts by mass Cellulose acylate solution (LA4) 11.3 parts by mass

(Preparation of additive solution)
A liquid having the following composition was prepared and filtered through a filter paper having an average pore diameter of 47 μm to prepare an additive solution (LD4).

<Additive solution (LD4) composition>
Wavelength dispersion adjusting agent (UV-102) 7.3 parts by mass Methylene chloride 53.8 parts by mass Methanol 9.7 parts by mass 1-butanol 2.0 parts by mass Cellulose acylate solution (LA4) 12.8 parts by mass

(Preparation of mixed solvent solution for dilution)
A liquid having the following composition was prepared and filtered through a filter paper having an average pore diameter of 44 μm to prepare a mixed solvent liquid for dilution (LE4).

<Combined solvent solution for dilution (LE4) composition>
Methylene chloride 82 parts by mass Methanol 15 parts by mass 1-butanol 3 parts by mass

(Preparation of cellulose ester film (F7) of the present invention)
The solution was fed at a ratio of 80 parts by mass of the cellulose acylate solution (LA4) and 2.6 parts by mass of the additive solution (LD4) and mixed with a static mixer. This mixed solution was fed to the slit at the center of the pressure die for triple layer casting so that the film thickness after drying was 74 μm. Meanwhile, 80 parts by mass of a cellulose acylate solution (LA4), 2.4 parts by mass of a matting agent solution (LC4), 2.6 parts by mass of an additive solution (LD4) and 5 parts by mass of a mixed solvent solution for dilution (LE4) The solution was fed at a ratio and mixed with a static mixer. This mixed solution was fed to the slits at both ends of the pressure die for triple layer casting so that the film thickness after drying was 3 μm. In this way, three layers were laminated and cast uniformly on a stainless steel band having a surface temperature of 20 ° C. After drying until the residual solvent content was 60 to 80%, the film was peeled off from the stainless steel band at a speed of 45 m / min, and the film was fixed to a tenter device. At this time, the transport speed of the tenter was 1.02 times that of the band speed. The drying temperature in the tenter apparatus was changed from 70 ° C to 130 ° C stepwise. The film width at the exit was set to 1.01 times the film width at the entrance of the tenter device. After leaving the tenter device, it was further dried at 130 to 140 ° C. and wound up at a rate of 47 / min. In this manner, a cellulose ester film (F7) having a film thickness of 75 μm was obtained. The residual solvent amount at the time of winding was 0.3%. The Ry of the film was 0.3 μm. Re ₍₅₉₀₎ was 1.6 ± 0.7 nm and Rth ₍₅₉₀₎ was −5 ± 2 nm.
[Example 8]
(Preparation of cellulose ester film (F8) of the present invention)
76.2 parts by mass of the cellulose acylate solution (LA4) prepared in Example 7, 1.6 parts by mass of the matting agent solution (LC4) and 2.8 parts by mass of the additive solution (LD4) were mixed with a static mixer. And uniformly cast on a stainless steel drum cooled to -15 ° C. After cooling until the liquid temperature reached about −10 ° C., the film was peeled off from the drum at 60 m / min, and the film was fixed to a tenter device. At this time, the transport speed of the tenter was 1.08 times that of the drum speed. The drying temperature in the tenter apparatus was changed from 70 ° C to 130 ° C stepwise. The film width at the exit was 1.05 times the film width at the entrance of the tenter device. After leaving the tenter apparatus, the film was further dried at 130 to 140 ° C. and wound up at a speed of 65 m / min. Thus, the cellulose ester film (F8) of the present invention having a film thickness of 72 μm was obtained. The residual solvent amount at the time of winding was 0.3%. The Ry of the film was 0.3 μm. Re ₍₅₉₀₎ was 1.8 ± 0.6 nm and Rth ₍₅₉₀₎ was −3 ± 5 nm.

[Example 9]
In place of cellulose acylate (AR2, AP2) in Example 7, cellulose acylate (AR3: derived from cotton linter, acetylation degree 2.93, 6% viscosity 286 mPa · s, AP3: derived from wood pulp, acetylation degree 2. 89, 6% viscosity (92 mPa · s) was used to produce a film (F9) of the present invention in the same manner as in Example 7. The film (F9) had a film Ry of 0.2 μm. Re ₍₅₉₀₎ was 1.9 ± 0.8 nm and Rth ₍₅₉₀₎ was 4 ± 6 nm.

[Example 10]
Cellulose acylate (AR4: derived from cotton linter, acetylation degree 1.96, propionylation degree 0.83, 6% viscosity 358 mPa · s, AP3: wood pulp instead of cellulose acylate (AR2, AP2) of Example 7 A film (F10) of the present invention was produced in the same manner as in Example 7, except that the origin, acetylation degree 2.89, and 6% viscosity 92 mPa · s) were used. The film (F10) had a film Ry of 0.3 μm. Re ₍₅₉₀₎ was 7 ± 1.8 nm and Rth ₍₅₉₀₎ was between 19 ± 6 nm.

[Comparative Example 1]
A cellulose acylate film F11 of a comparative example was produced in the same manner as in Example 1 except that the cellulose acylate (AR1) and the cellulose acylate (AP1) of Example 1 were 0 parts by mass and 100 parts by mass, respectively. . The thickness of the film F11 was 80 μm, and the Ry of the film was as large as 0.9 μm. Re ₍₅₉₀₎ was 3.4 ± 0.8 nm and Rth ₍₅₉₀₎ was −6 ± 3 nm.

[Comparative Example 2]
A cellulose acylate film F12 of a comparative example was produced in the same manner as in Example 1 except that the cellulose acylate (AR1) and the cellulose acylate (AP1) of Example 1 were 3 parts by mass and 97 parts by mass, respectively. . The thickness of the film F12 was 79 μm, and the Ry of the film was as large as 0.8 μm. Re ₍₅₉₀₎ was 3.5 ± 0.9 nm and Rth ₍₅₉₀₎ was −6 ± 3 nm.

  The above results are summarized in Table 1. The retention results were also shown.

[Example 11]
(Preparation of polarizing plate)
The cellulose acylate film (F1) of the present invention obtained in Example 1 was immersed in a 1.5 N aqueous sodium hydroxide solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing bathtub, and neutralized using 0.1 N sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, a cellulose acylate film (F101) having a saponified surface was obtained. A similar surface saponification treatment was performed on a commercially available cellulose acetate film TD80UF (Fuji Photo Film Co., Ltd.) to prepare a film (F200).
Subsequently, a rolled polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizing film. Using a 3% aqueous solution of polyvinyl alcohol (PVA-117H made by Kuraray) as an adhesive, a film (F101) was bonded to one side of the polarizing film, and a film (F200) was bonded to the other side to obtain a polarizing plate (P1). At this time, the films (F101) and (F200) were pasted so that the slow axis was parallel to the transmission axis of the polarizing film.

  Similarly, polarizing plates (P2) to (P10) were prepared for the cellulose acylate films (F2) to (F10) prepared in Examples 2 to 10 of the present invention. All the cellulose acylate films of the present invention had sufficient bonding properties with the stretched polyvinyl alcohol, and had excellent polarizing plate processing suitability.

[Example 12]
(Incorporation into liquid crystal display devices)
<Preparation of counter polarizing plate>
Polarized light in the same manner as in Example 11 except that both films to be bonded on both sides of the polarizing film were (F300) (saponified commercially available cellulose acetate film TD80UF (Fuji Photo Film Co., Ltd.)). A plate (P0) was produced.
<Production of IPS mode liquid crystal cell>
On one glass substrate, electrodes were arranged so that the distance between adjacent electrodes was 20 μm, and a polyimide film was provided as an alignment film thereon, and a rubbing treatment was performed. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

On the backlight side of the produced IPS mode liquid crystal cell, the polarizing plate (P1) of the present invention prepared in Example 11 is used so that its absorption axis is parallel to the rubbing direction of the liquid crystal cell and the cellulose acylate of the present invention. The film (F101) was attached so as to be on the liquid crystal cell side. Subsequently, a polarizing plate (P0) was attached to the other side of the IPS mode liquid crystal cell in a crossed Nicols arrangement.
The black color of the liquid crystal display device thus fabricated was observed in all azimuth directions at a polar angle of 60 degrees, but almost no color change was felt.
Further, the film had an excellent viewing angle in the left, right, up and down directions. Therefore, it was found that the cellulose ester film of the present invention was excellent for optical use.

In addition, instead of the polarizing plate (P1), the polarizing plates (P2) to (P10) were similarly used to create a liquid crystal display device, and as a result of evaluation, both of them used the polarizing plate (P1). As well as, good results were obtained.

Claims (10)

In-plane retardation value Re ₍₅₉₀₎ and film thickness, including the steps of casting a dope in which cellulose ester is dissolved in a solvent onto a support, peeling the film from the support, and drying the peeled film A method for producing a cellulose ester film having a direction retardation value Rth ₍₅₉₀₎ satisfying the following formulas (I) and (II), wherein the cellulose ester is derived from at least one kind of cotton linter and at least one kind of wood as the cellulose ester: A method for producing a cellulose ester film, wherein at least a cellulose ester derived from pulp is used, and a ratio of the cellulose ester derived from the cotton linter in the total cellulose ester is 5% by mass or more and 90% by mass or less.
Formula (I) 0 ≦ Re ₍₅₉₀₎ ≦ 10
Formula (II) −25 ≦ Rth ₍₅₉₀₎ ≦ 25
[Wherein, Re _(λ) is an in-plane retardation value (unit: nm) at 25 ° C. and 60% RH at a wavelength of λ nm. Rth _(λ) is a retardation value (unit: nm) in the film thickness direction at a wavelength of λ nm at 25 ° C. and 60% RH. ] The cellulose according to claim 1, wherein both the cellulose ester derived from cotton linter and the cellulose ester derived from wood pulp are acylated esters, and the acyl substitution degree (X + Y) both satisfies the following formula (10). A method for producing an ester film.
Formula (10) 2.7 <X + Y ≦ 3.0
[Wherein, X is the degree of acetyl substitution, and Y is the degree of acyl substitution other than acetyl. ]   The quotient obtained by dividing the larger value of the 6% viscosity of the cotton linter-derived cellulose ester and the 6% viscosity of the wood pulp-derived cellulose ester by the smaller value is 1.2 or more. The manufacturing method of the cellulose-ester film of claim | item 1 or claim 2.   The cellulose-ester film produced by the manufacturing method of the cellulose-ester film of any one of Claims 1-3.   The cellulose ester film according to claim 4, wherein the cellulose ester film contains a retardation reducing agent.   6. The cellulose ester film according to claim 4 or 5, wherein the cellulose ester film contains a retardation wavelength dispersion adjusting agent.   The cellulose ester film according to any one of claims 4 to 6, wherein the maximum height Ry of surface irregularities of the cellulose ester film is 0.5 µm or less.   The thickness of the said cellulose-ester film is 30-120 micrometers, The cellulose-ester film of any one of Claims 4-7 characterized by the above-mentioned.   A polarizing plate in which a protective film is bonded to both sides of a polarizing film, wherein at least one of the protective films is the cellulose ester film according to any one of claims 4 to 8.   A liquid crystal display device using at least one of the cellulose ester film according to claim 4 and the polarizing plate according to claim 9.