JP2007106794A - Cellulose ester film, manufacturing method of the same, optical compensation film, polarizing plate and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film little in the retardation of the thickness direction and the retardation within the plane, hard to cause breakage and the like at the time of the manufacture, and well-balanced in the mechanical characteristics and dimensional stability in the casting direction and the direction perpendicular to it; its manufacturing method; and an optical compensation film, a polarizing plate and a liquid crystal display using the cellulose ester film. <P>SOLUTION: The cellulose ester film is a transparent film in which the retardation value of the film thickness direction on the wavelength of 590 nm (Rth(590)) is ≥-25 nm and ≤25 nm, the retardation value within the plane (Re(590)) is ≥0 nm and ≤10 nm, and the lag phase axis direction within the film plane regarding the wavelength 590 nm is different by 10° or more in arbitrary places of the width direction. Its manufacturing method is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

Liquid crystal display devices are widely used in monitors for personal computers and portable devices, and for television applications because of their various advantages, such as low voltage and low power consumption, enabling miniaturization and thinning. In such a liquid crystal display device, various modes have been proposed depending on the alignment state of the liquid crystal in the liquid crystal cell. Conventionally, the TN has an alignment state twisted by about 90 ° from the lower substrate to the upper substrate of the liquid crystal cell. Mode is mainstream.
In general, a liquid crystal display device includes a liquid crystal cell, a retardation film, and a polarizing plate. The retardation film is used for eliminating image coloring or expanding the viewing angle, and a stretched birefringent film or a film obtained by applying a liquid crystal to a transparent film is used. For example, Japanese Patent No. 2587398 discloses a technique in which an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film and aligned and fixed is applied to a TN mode liquid crystal cell to widen the viewing angle.
However, a liquid crystal display device for television that is expected to be viewed from various angles on a large screen has a strict requirement for viewing angle dependency, and even with the above-described method, the requirement cannot be satisfied. In recent years, the required performance for liquid crystal display devices for monitors has also increased. For this reason, various studies have been made on liquid crystal display devices different from the TN mode, such as an IPS (In-Plane Switching) mode, an OCB (Optically Compensatory Bend) mode, and a VA (Vertically Aligned) mode.

Cellulose acylate film has higher moisture permeability and higher adhesion to polarizers of polarizing plates, such as PVA, which has high hydrophilicity, and is generally used as a protective film for polarizing plates. In general, a cellulose acetate film is used.
A cellulose acetate film is highly suitable as a protective film for a general polarizing plate because of its high optical isotropy. Recently, however, a retardation film having desired optical anisotropy has been required for the liquid crystal display devices of various modes as described above in order to improve the viewing angle dependency and other characteristics.
On the other hand, the cellulose acetate film has small in-plane retardation and is optically isotropic, but has a retardation of several tens of nm in the thickness direction. There were some aspects that were not isotropic. Cellulose acylate films with even more optical isotropy have been demanded as protective films for polarizing plates of various liquid crystal display devices, substrates for retardation plates, and the like. (For example, Patent Document 1)

Recently, liquid crystal display devices are widely used not only for PC monitors and portable devices but also for television applications, and there is a strong demand for better contrast and color viewing angle characteristics than before. It has become like this. In addition, there is a strong need for an increase in size, price, and thickness in television applications, and a protective film and retardation film that are uniform in performance over a large area, are thin, and are low in cost. In order to satisfy these requirements, there has been a need for a film with excellent mechanical properties and manufacturing stability that eliminates the limitations and problems of retardation as described above and is less prone to cutting even when thinned. Yes.
JP2002-249599

  The present invention has been made in view of the above circumstances, and the problem of the present invention is that the retardation in the thickness direction, the in-plane retardation is small, cutting is difficult to occur during production, and the direction perpendicular to the casting direction. Is to provide a cellulose ester film balanced in mechanical properties and dimensional stability, and a method for producing the same, and when the cellulose ester film is incorporated into a liquid crystal display device, the viewing angle characteristics can be improved. It is to provide a compensation film and a polarizing plate. Another problem is to provide a liquid crystal display device having excellent viewing angle characteristics.

  As a result of intensive studies by the inventors of the present invention, the use of a compound that inhibits the cellulose ester in the film, particularly cellulose acylate from being oriented in the plane and in the film thickness direction, and an acyl substitution degree of 2.70 to It has been found that the use of 3.00 cellulose acylate is beneficial for sufficiently reducing optical anisotropy and bringing Re and Rth close to zero.

  Furthermore, the inventors of the present invention provide in-plane retardation and retardation in the thickness direction by applying tension in a balanced manner in the casting direction and in the direction perpendicular to the casting direction during the production of the cellulose ester film. By making the angle that the slow axis direction in the plane makes with the film casting direction close to zero and not uniform in the film width direction, that is, by varying the slow axis direction, It has been found that it is possible to prevent the mechanical properties and dimensional changes of the material from greatly differing in the casting direction or the direction perpendicular thereto. It has also been found that there is an effect in reducing fluctuations associated with Rth temperature changes. Based on this knowledge, we were able to achieve the task with the following configuration.

(1) Thickness direction retardation value at a wavelength of 590 nm Rth (590) is -25 nm or more and 25 nm, and in-plane retardation value Re (590) is 0 nm or more and 10 nm or less. A cellulose ester film characterized in that the direction of the slow axis in the film plane at 590 nm differs by 10 ° or more at an arbitrary position in the width direction.
(2) The cellulose ester film is characterized in that the average direction of the slow axis in the film plane at a wavelength of 590 nm is not more than 20 ° away from the casting direction or the direction perpendicular to the casting direction. The cellulose ester film according to claim 1.
(3) The cellulose ester film as described in (1) or (2) above, wherein the film width of the cellulose ester film is 600 mm or more.
(4) The cellulose ester film according to any one of (1) to (3) above, wherein the degree of ester substitution (X + Y) of the cellulose ester film satisfies the following formula (I):
Formula (I) 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. ]
(5) The cellulose ester film as described in any one of (1) to (4) above, which contains at least one compound that lowers the retardation Rth in the film thickness direction.
(6) The dimensional change rate at 50 ° C. and 90% RH240h in the casting direction and the direction perpendicular to the casting direction of the cellulose ester film is 0.3% or less, and the dimensional change rate and casting in the casting direction The cellulose ester film according to any one of (1) to (5) above, wherein a difference in dimensional change rate in a direction perpendicular to the direction is 0.2% or less.
(7) Both the tear strength in the casting direction and the direction perpendicular to the casting direction of the cellulose ester film are 0.01 N or more, and the ratio of the tear strength in the TD direction to the tear strength in the MD direction is 0.7 or more. It is 1.4 or less, The cellulose-ester film in any one of said (1)-(6) characterized by the above-mentioned.

(8) The cellulose ester film according to any one of (1) to (7), wherein the thickness of the cellulose ester film is 30 to 200 μm.
(9) A cellulose ester solution (hereinafter also referred to as a dope) is prepared, the dope is cast on a support, the cast film is peeled off as a film from the support, and both widthwise ends of the peeled film are removed. A method for producing a cellulose ester film, which is held by a tenter (film width direction gripping device) to hold the width of the film and is dried, and further dried after being detached from the tenter, both ends of the film in the width direction The tension applied in the film width direction in the tenter section holding the film is 3 kgf / m or more and less than 10 kgf / m, and the tension applied in the film transport direction is 1 kgf / m or more in the section where the amount of residual solvent is 15% or more. The cell according to any one of (1) to (8) above, which is 20 kgf / m or less. Method of manufacturing a loin ester film.
(10) Re (590) = 0 to at least one cellulose ester film according to any one of (1) to (8) or a cellulose ester film produced by the production method according to (9) An optical compensation film comprising an optically anisotropic layer having a thickness of 200 nm and | Rth (590) | = 0 to 400 nm.
(11) 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 (1) to (8) above, (9 A polarizing plate characterized in that it is a cellulose ester film produced by the production method as described in 1) or the optical compensation film as described in (10) above.
(12) The cellulose ester film according to any one of (1) to (8), the cellulose ester film produced by the production method according to (9), the optical compensation film according to (10), and A liquid crystal display device comprising at least one of the polarizing plates according to (11) above.
(13) The liquid crystal display device according to (12), wherein the liquid crystal display device has an IPS mode liquid crystal cell.

Hereinafter, the present invention will be described in detail.
[Retardation of cellulose ester film]
The cellulose ester film of the present invention has a retardation value Rth _{(590) in the} film thickness direction and an in-plane retardation value Re ₍₅₉₀₎ in the following ranges.
Rth ₍₅₉₀₎ is in the range of −25 nm to 25 nm, and Re ₍₅₉₀₎ is in the range of 0 nm to 10 nm.
Rth ₍₅₉₀₎ is preferably from −15 nm to 15 nm, and more preferably from −5 nm to 5 nm. On the other hand, Re ₍₅₉₀₎ is preferably 0 nm or more and 5 nm or less, more preferably 0 nm or more and 3 nm or less, and further preferably 0 nm or more and 1 nm or less.
Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA · 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is a wavelength λnm from the direction inclined by +40 degrees with respect to the normal direction of the film, with Re (λ) and the in-plane slow axis (determined by KOBRA · 21ADH) as the tilt axis (rotation axis). The retardation value measured by the incident light and the slow axis in the plane as the tilt angle (rotation axis), and the light of wavelength λ nm from the direction inclined by 40 degrees with respect to the film normal direction. KOBRA · 21ADH is calculated based on the retardation values measured in a total of three directions of the measured retardation values. Here, as the assumed value of the average refractive index, 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. In this specification, the wavelength λ is usually 590 nm, and the measurement environment is measured at 25 ° C. and 60% unless otherwise specified.

The cellulose ester film of the present invention is a cellulose ester film characterized in that the direction of the in-plane slow axis is different by 10 ° or more at any place in the width direction, and the slow phase at any two places The smaller angle formed by the shaft is 10 ° or more. That is, the cellulose ester film of the present invention does not have the axis oriented only in a certain direction, but has a distribution in the angle of the axis. Preferably, it is different by 15 ° or more at any place in the width direction, and more preferably, it is different by 30 ° or more.
If the slow axis direction is defined as, for example, the angle of the axis parallel to the casting direction is 0 °, the right angle with respect to the casting direction is plus, and the left angle is minus, any In order to calculate the angle formed by the slow axis at these two points, and to calculate the average direction and standard deviation at the measurement points described below, the range of the shaft angle is a value between −90 ° and + 90 °. , Or a value between 0 ° and + 180 °, or a value between 0 ° and −180 ° can be set and calculated as appropriate.
When the slow axis is distributed substantially in the casting direction, the slow axis at each location is preferably in the range of −90 ° to + 90 °, and the slow axis is generally in the casting direction. When the distribution is directed in the direction perpendicular to the vertical axis, the slow axis at each location is preferably in the range of 0 ° to + 180 ° or 0 ° to −180 °.
When the in-plane retardation value is close to the measurement limit, the profile in the width direction of the slow axis angle is increased from −90 ° within a certain range, and after passing through 0 °, + 90 ° (ie, Some of them exhibit a behavior that reaches −90 ° and further increases from −90 °, and this is also preferable.
Thus, it is considered that the slow axis direction has a distribution, thereby reducing the anisotropy of mechanical strength and the anisotropy of dimensional change. A film having a slow axis direction is excellent in physical properties such as tear strength in a certain direction, but is very inferior in physical properties in a direction perpendicular thereto. The film of the present invention has appropriate physical properties in all directions, and the size does not vary greatly depending on the direction.

Moreover, the dispersion | variation in the axial angle of the cellulose-ester film of this invention can be evaluated by calculating the standard deviation. When the number of measurement points is N, the standard deviation σ can be calculated from the following when the average value of the measured values x ₁ , x ₂ ,..., X _N is x _av .
_{^{σ 2 = {(x 1 -x}} av) 2 + (x 2 -x av) 2 + ··· + (x N -x av) 2} / (N-1)
A preferable range of the standard deviation is 3 ° to 80 °, more preferably 5 ° to 40 °, and particularly preferably 8 ° to 20 °.

  In the cellulose ester film of the present invention, it is preferable that the average direction of the slow axis in the film plane at a wavelength of 590 nm is not separated from the casting direction or a direction perpendicular to the casting direction by more than 20 °. When the direction parallel to the casting direction is 0 ° and the angle of the slow axis is in the range of −90 ° to + 90 °, the angle formed by the average of the slow axis with respect to the casting direction is −20 ° to 20 °. It is preferably 70 ° to 90 °, −90 ° to −70 °, or Although Re and Rth of the present invention are extremely small, if they are not zero, they have finite values. In such a case, the average direction of the slow axis is preferably within the above range from the viewpoint of suppressing light leakage and tint change when the polarizing plate is bonded to the polarizer. . More preferably, it is −15 ° to 15 °, or −90 ° to −75 °, or 75 ° to 90 °, and further preferably −10 ° to 10 °, or −90. It is that it is ° to -80 ° or 80 ° to 90 °.

  The direction of the slow axis can be determined by using a measuring instrument (for example, KOBRA 21DH (manufactured by Oji Scientific Instruments Co., Ltd.)) and measuring the light with a wavelength of λ nm incident on the film normal direction. In the present specification, unless otherwise specified, values measured at 590 nm are shown.

The cellulose ester film of the present invention preferably has a small difference between Re and Rth at wavelengths of 400 nm and 700 nm, | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ |. , | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 10 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 35. More preferably, | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 5 and | Rth ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 25, and | Re ₍₄₀₀₎ −Re ₍₇₀₀₎ | ≦ 3 and | Rth It is particularly preferable that ₍₄₀₀₎ −Rth ₍₇₀₀₎ | ≦ 15.

Further, the cellulose ester film of the present invention has a difference between Re and Rth at 10 ° C. and 40 ° C., | Re _{(10 ° C.)} − Re _{(40 ° C.)} | and | Rth _{(10 ° C.)} − Rth _{(40 ° C.)} | Is preferably small, and | Re _{(10 ° C.)} − Re _{(40 ° C.)} | ≦ 10 and | Rth _{(10 ° C.)} − Rth _{(40 ° C.)} | ≦ 15 are preferable. More preferably, | Re _{(10 ° C.)} − Re _{(40 ° C.)} | ≦ 5 and | Rth _{(10 ° C.)} − Rth _{(40 ° C.)} | ≦ 10, and | Re _{(10 ° C.)} − Re _{(40 ° C.)} It is particularly preferable that | ≦ 3 and | Rth _{(10 ° C.)} − Rth _{( 40 ° C.)} | ≦ 5.

[Retardation variation]
The variation in retardation value is 17 points in the width direction of the film formed (center, end (2% of the total width from each end), 2 points in the middle between the center and end, and the middle of the above points. The difference between the maximum value and the minimum value of 4 points and 8 intermediate points sampled every 100 m in the longitudinal direction is preferably 3 nm or less, more preferably 2 nm or less. 1 nm or less is particularly preferable.

<Cellulose ester>
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), C5-C20 aliphatic and aromatic. Examples thereof include carboxylic acid having a ring and cellulose ester such as cellulose ester, cellulose acetate phthalate, cellulose acetate trimellitate, and cellulose nitrate. Moreover, these mixtures can be used.

  The cellulose ester is preferably used in the present invention, but more preferably, the degree of substitution of the cellulose ester is represented by X as the degree of acetyl substitution by acetic acid and Y as the degree of acyl substitution by other than acetic acid such as propionic acid or butyric acid. In this case, the cellulose ester satisfies the following formula (I).

Formula (I) 2.7 <X + Y ≦ 3.0
In this case, X + Y in the range of 2.7 to 3.0 has high resin solubility, and a high concentration dope (a solution in which a resin is dissolved in a solvent is hereinafter referred to as a dope) can be produced. This is because it is more advantageous during drying.

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. The higher the degree of substitution of the cellulose ester, the smaller the intrinsic birefringence can be, and furthermore, a negative value, which is preferable in controlling the retardation value. More preferably, it is 2.85 or more and 3.0 or less, More preferably, it is 2.89 or more and 3.0 or less, Most preferably, it is 2.91 or more and 3.0 or less.
The measuring method of the substitution degree of these acyl groups can be measured according to ASTM-D817-96.

  The cellulose used as a raw material for the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. In addition, the cellulose derivatives obtained from these can be used alone or in an arbitrary ratio, but it is preferable to use 50% by mass or more of either cotton linter or wood pulp.

  When the molecular weight of the cellulose ester film is small, the elastic modulus is too low, and when the molecular weight is too high, the viscosity of the cellulose ester solution becomes too high, and the productivity is lowered. The molecular weight of the cellulose ester is preferably 70,000 to 200,000, more preferably 100,000 to 200,000 in terms of number average molecular weight (Mn). The cellulose ester used in the present invention preferably has an Mw / Mn ratio of 1.0 or more and less than 5.0, more preferably 2.1 or more and less than 3.3, and particularly preferably 2.3 or more and less than 3.0. is there.

  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 weight 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 three Showa Denko Co., Ltd.)
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.

The degree of polymerization of the cellulose ester is preferably 200 to 800, more preferably 250 to 650, still more preferably 250 to 450, and particularly preferably 250 to 400 in terms of viscosity average degree of polymerization. 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.
The viscosity of the cellulose solution is preferably 80 cps (80 mPa · s) to 500 cps (500 mPa · s) at a cellulose concentration of 6% by weight, more preferably 120 cps (120 mPa · s) to 400 cps (400 mPa · s). Preferably, it is 180 (180 mPa · s) cps to 300 cps (300 mPa · s).

(Retardation reducing agent)
The cellulose ester film of the present invention preferably contains at least one compound that lowers retardation.
In particular, the retardation reducing agent of the present invention is a compound that reduces retardation in the thickness direction (also referred to as the film thickness direction). From the viewpoint of solubility in cellulose esters, particularly cellulose acylate, the letter used in the present invention. The retardation reducing agent is preferably a compound having an octanol-water partition coefficient (log P value) of 0 to 7. A compound having a log P value of more than 7 is poor in compatibility with cellulose acylate, and tends to cause film turbidity or powder blowing. In addition, since the compound having a log P value of less than 0 has high hydrophilicity, the water resistance of the cellulose acetate film may be 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 permeation 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., Vol. 19, p.71 (1984)) and the like are preferably used. J. Chem. Inf. Comput. Sci., 27, 21 (1987)). 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.
Specific examples include compounds represented by the following general formula (1) and general formula (2).

In the general formula (1), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. The total number of carbon atoms of R ¹ , R ² and R ³ is preferably 10 or more. In R ¹ , R ² and R ³ , 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 ³¹ represents an alkyl group or an aryl group, and R ³² and R ³³ 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 ³¹ , R ³² and R ³³ 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 the optical anisotropy, the optical anisotropy is sufficiently reduced by suppressing the orientation of the polymer in the cellulose ester film in the plane and in the film thickness direction, and Re is zero. And Rth can be negative. The compound that lowers the optical anisotropy 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 cellulose ester film of the present invention preferably contains at least one compound that reduces optical anisotropy 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 Rth (nm) of a film containing A% of a compound that lowers Rth, Rth (0) is Rth (nm) of a film not containing a compound that lowers Rth, and A is the cellulose. This is the mass (%) of the compound when the solid content mass of the ester polymer is 100. ]
The above formulas (a) and (b) are: (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 adjusting agent)
The cellulose ester film in the present invention may contain a compound that adjusts wavelength dispersion. The compound for adjusting the wavelength dispersion will be described. In order to bring the Rth wavelength dispersion of the cellulose ester film used in the present invention closer to zero in the entire visible light range, a compound that reduces the Rth wavelength dispersion ΔRth = | Rth (400) −Rth (700) | It is preferable to contain at least one kind of “wavelength dispersion adjusting agent”.

The chromatic dispersion adjusting agent preferably has absorption in the ultraviolet region of 200 nm to 400 nm.
In general, the Re and Rth values of cellulose ester films, particularly cellulose acylate films, have dispersion characteristics that are greater on the longer wavelength side than on the shorter wavelength side. On the other hand, a compound having absorption in the ultraviolet region of 200 nm to 400 nm has a wavelength dispersion characteristic in which the absorbance on the long wavelength side is larger than that on the short wavelength side. Therefore, wavelength dispersion can be smoothed by increasing Re and Rth on the short wavelength side of the cellulose acylate film with a compound having an appropriate ultraviolet absorption.

  The in-plane variation of chromatic dispersion affects the variation in optical performance, particularly the color viewing angle characteristics. Therefore, the wavelength dispersion adjusting agent is required to be sufficiently uniformly compatible with cellulose acylate. The absorption band range in the ultraviolet region of such a wavelength dispersion adjusting agent is preferably 200 nm 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. In that respect, a compound having absorption in the ultraviolet region of 200 to 400 nm and reducing the | Re (400) -Re (700) | and | Rth (400) -Rth (700) | When added, the spectral transmittance is required to be excellent. In the cellulose ester film of the present invention, the spectral transmittance at a wavelength of 380 nm is preferably 45% to 95%, and the spectral transmittance at a wavelength of 350 nm is preferably 10% or less.

  As described above, the wavelength dispersion adjusting agent preferably used in the present invention preferably has a molecular weight of 250 to 1000 from the viewpoint of volatility, more preferably 260 to 800, still more preferably 270 to 800, Especially 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.

  It is preferable that the wavelength dispersion adjusting agent does not volatilize during the dope casting and drying process for producing the cellulose ester film.

  The addition amount of the wavelength dispersion adjusting agent preferably used in the present invention described above is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass with respect to the solid content of the cellulose ester. It is particularly preferably 0.2 to 10% by mass.

These wavelength dispersion adjusting agents may be used alone or in combination of two or more compounds at an arbitrary ratio.
Further, the timing of adding these wavelength dispersion adjusting agents may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

  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 used as the wavelength dispersion adjusting agent, a compound represented by the following general formula (3) is preferably used as the wavelength dispersion adjusting agent of the present invention.

General formula (3): Q1-Q2-OH
(In the formula, Q1 represents a nitrogen-containing aromatic heterocycle, and Q2 represents an aromatic ring.)

Q1 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. Examples of the nitrogen-containing aromatic heterocycle include imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, selenazole, benzotriazole, benzothiazole, benzoxazole, benzoselenazole, thiadiazole, oxadiazole, naphthothiazole, and naphthoxazole. , Azabenzimidazole, purine, pyridine, pyrazine, pyrimidine, pyridazine, triazine, triazaindene, tetrazaindene and the like, more preferably a 5-membered nitrogen-containing aromatic heterocycle, For imidazole, pyrazole, triazole, tetrazole, thiazole, oxazole, benzotriazole, benzothiazole, benzoxazole, thiadiazole, oxadiazole Preferably, particularly preferably benzotriazole ring.
The nitrogen-containing aromatic heterocycle represented by Q1 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 Q2 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 (for example, a benzene ring or a naphthalene ring), more preferably 6 to 20 carbon atoms. Of the aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and particularly preferably 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. Phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene, etc., preferably pyridine, triazine, quinoline It is a ring.
The aromatic ring represented by Q2 is preferably an aromatic hydrocarbon ring, more preferably a naphthalene ring or a benzene ring, and particularly preferably a benzene ring. Q2 may further have a substituent, and the substituent T described below is preferable as the substituent.

  Examples of the substituent T include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert- And each group such as 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, Particularly preferably, it has 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, 2-butenyl, 3-pentenyl, etc.); alkynyl group (preferably 2 to 20 carbon atoms, more preferably 2 carbon atoms) To 12 and particularly preferably 2 to 8 carbon atoms, for example, groups such as propargyl and 3-pentynyl); aryl groups (preferably Or 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, and the like. A substituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, and particularly preferably 0 to 6 carbon atoms; for example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino, etc. An alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy, butoxy and the like). An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, Oxy include the groups such as 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, and examples thereof include acetyl, benzoyl, formyl, and pivaloyl groups); alkoxy A carbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl and ethoxycarbonyl groups); aryloxycarbonyl Group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl group); acyloxy group (preferably having 2 carbon atoms) To 20, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as an acetoxy group Benzoyloxy group, etc.); acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetylamino group, benzoylamino group, etc. An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group). Aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably having 7 to 12 carbon atoms, such as phenyloxycarbonylamino group); Group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably A prime number 12, for example, methanesulfonylamino group, and benzenesulfonylamino group).;

Sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc. 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, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl) And alkylthio groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms. For example, each group such as methylthio and ethylthio is Arylthio group (preferably having 6 to 20 carbon atoms, more preferably A prime number of 6 to 16, particularly preferably a carbon number of 6 to 12, such as a phenylthio group, and the like; a sulfonyl group (preferably having a carbon number of 1 to 20, more preferably a carbon number of 1 to 16, and particularly preferably carbon). And a sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms). For example, each group 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 group (preferably having 1 to 20 carbon atoms, more preferably charcoal) 1 to 16, particularly preferably 1 to 12 carbon atoms, and examples thereof include groups such as diethyl phosphoric acid amide and phenyl phosphoric acid amide); hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine) 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 atom) And the hetero atom includes, for example, a nitrogen atom, an oxygen atom, a sulfur atom, specifically imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc. Silyl group (preferably having 3 to 40 carbon atoms, more preferably carbon 3-30, particularly preferably 3-24 carbon atoms, and examples thereof include trimethylsilyl group and triphenylsilyl group). These substituents T may be further substituted with a substituent. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked together to form a ring.

  The compound represented by the general formula (3) is preferably a compound represented by the following general formula (3-A).

(In general formula (3-A), R ^1, R ^2, R ^3, R ^4, R ^5, R ^6, R ⁷ and R ⁸ each independently represents a hydrogen atom or a substituent.)

In general formula (3-A), R ^1, R ^2, R ^3, R ^4, R ^5, R ^6, R ^7, and R ⁸ each independently represent a hydrogen atom or a substituent, The above-mentioned substituent T can be applied. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.
R ¹ and R ³ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkyloxy group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom. More preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, still more preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, particularly preferably having 1 to 12 carbon atoms. An alkyl group (preferably having 4 to 12 carbon atoms).

In general formula (3-A), R ² and R ⁴ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, alkyloxy group, substituted or unsubstituted amino group, alkoxy group, 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, still more preferably a hydrogen atom and a carbon 1-12 alkyl group, Particularly preferred are a hydrogen atom and a methyl group, and most preferred is a hydrogen atom.

In general formula (3-A), R ⁵ and R ⁸ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, alkyloxy group, substituted or unsubstituted amino group, alkoxy group, 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, still more preferably a hydrogen atom and a carbon 1-12 alkyl group, Particularly preferred are hydrogen atom and methyl group, and most preferred is hydrogen atom.

In general formula (3-A), R ⁶ and R ⁷ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, alkyloxy group, substituted or unsubstituted 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, still more preferably hydrogen atom and halogen atom, particularly preferably hydrogen. Atom, chlorine atom.

  The compound represented by the general formula (3) is more preferably a compound represented by the following general formula (3-B).

(In general formula (3-B), R ¹ , R ³ , R ⁶ and R ⁷ have the same meanings as in general formula (3-A), and preferred ranges are also the same.)

  Specific examples of the compound represented by formula (3-B) (compounds UV1 to UV23) are shown below, but the present invention is not limited to the following specific examples.

  Among the above-mentioned benzotriazole-based compounds (wavelength dispersion adjusting agents), when a cellulose ester film is produced without including a molecular weight of 320 or less, it is preferable in terms of retention.

  Moreover, as a benzophenone type compound which is one of the wavelength dispersion adjusting agents used in the present invention, a compound represented by the following general formula (4) can also be preferably used.

(In General Formula (4), Q ¹ and Q ² each independently represent an aromatic ring. X represents NR (R: hydrogen atom or substituent), oxygen atom or sulfur atom.)

In the general formula (4), the aromatic ring represented by Q ¹ and Q ² 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 (for example, a benzene ring or a naphthalene ring), more preferably 6 to 6 carbon atoms. 20 is an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 12 carbon atoms, and particularly preferably a benzene ring.
The aromatic heterocycle is preferably an aromatic heterocycle containing at least one of an oxygen atom, a nitrogen atom or a 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. , Quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. Preferable aromatic heterocycles are pyridine, triazine, and quinoline.

The aromatic ring represented by Q ¹ and Q ² in the general formula (4) is preferably an aromatic hydrocarbon ring, more preferably an aromatic hydrocarbon ring having 6 to 10 carbon atoms, and further preferably a substituted ring. Or it is an unsubstituted benzene ring.
Q ¹ and Q ² in the general formula (4) may further have a substituent, and a substituent T1 described later is preferable, but the substituent contains a carboxylic acid group, a sulfonic acid group, or a quaternary ammonium group. There is no. Further, if possible, substituents may be linked to form a ring structure.

  In the general formula (4), X represents NR (R represents a hydrogen atom or a substituent. Substituent T1 described later can be applied as the substituent), an oxygen atom or a sulfur atom. X is preferably NR (preferably R is an acyl group or a sulfonyl group, and these substituents may be further substituted) or an oxygen atom, and particularly preferably an oxygen atom.

  Examples of the substituent T1 include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert. -Each group such as 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). , Particularly preferably having 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, 2-butenyl, 3-pentenyl and the like.); Alkynyl group (preferably having 2 to 20 carbon atoms, more preferably carbon number) 2 to 12, particularly preferably 2 to 8 carbon atoms, for example, propargyl group, 3-pentynyl group, etc.); aryl group Preferably it has 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like. Substituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, for example, amino, methylamino, dimethylamino, diethylamino, dibenzylamino groups Alkoxy groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy, butoxy and the like. Aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms). A phenyloxy group, a 2-naphthyloxy group, etc.); an acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms; , Benzoyl, formyl, pivaloyl, etc.));

An alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonyl group and an ethoxycarbonyl group); aryloxycarbonyl Group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably 7 to 10 carbon atoms, such as phenyloxycarbonyl group); acyloxy group (preferably having 2 carbon atoms) -20, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, for example, an acetoxy group, a benzoyloxy group, etc.); an acylamino group (preferably 2 to 20 carbon atoms, more preferably Has 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetylamino group, benzo An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group). Aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably having 7 to 12 carbon atoms, such as phenyloxycarbonylamino group) A sulfonylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methanesulfonylamino group and a benzenesulfonylamino group); Sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably having 0 to 16 carbon atoms, especially Mashiku is 0-12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, and each group such as phenylsulfamoyl).;

A carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like. Alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include methylthio and ethylthio groups); arylthio group ( Preferably it has 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenylthio group, etc.); a sulfonyl group (preferably 1 to 20 carbon atoms, more Preferably it is C1-C16, Most preferably, it is C1-C12, for example, a mesyl group, a tosyl group etc. A sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methanesulfinyl group, a benzenesulfinyl group, 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, and examples thereof include ureido, methylureido, phenylureido and the like); phosphorus Acid amide group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide group and phenyl phosphoric acid amide group) 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; A cyclic 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 and oxygen Children, sulfur atoms, specifically, for example, imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl and the like; a silyl group (preferably having 3 carbon atoms) To 40, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyl and triphenylsilyl groups). 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.

  As the compound represented by the general formula (4), a compound represented by the following general formula (4-A) is preferable.

(In general formula (4-A), R ^1, R ^2, R ^3, R ^4, R ^5, R ^6, R ^7, R ⁸ and R ⁹ each independently represents a hydrogen atom or a substituent.)

R ^1, R ^2, R ^3, R ^4, R ^5, R ^6, R ^7, R ^8, and R ⁹ each independently represents a hydrogen atom or a substituent, and the substituent T 1 described above applies as the substituent. it can. Further, these substituents may be further substituted with another substituent, and the substituents may be condensed to form a ring structure.

R ^1, R ^3, R ^4, R ^5, R ^6, R ⁸ and R ⁹ are preferably a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, alkyloxy group, 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, still more preferably a hydrogen atom and a carbon 1 to 12 alkyl groups, particularly preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

R ² 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, or a halogen atom, more preferably a hydrogen atom or a carbon 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 1 to 20 carbon atoms. An alkoxy group, particularly preferably an alkoxy group having 1 to 12 carbon atoms.

R ⁷ 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 a carbon number of 1 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, 1-20 carbon atoms. Alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and still more preferably a methyl group), particularly preferably a methyl group or a hydrogen atom.

  The compound represented by the general formula (4) is more preferably a compound represented by the following general formula (4-B).

(In the general formula (4-B), R ¹⁰ 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. To express.)

In general formula (4-B), R ¹⁰ 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. As the group, the above-described substituent T can be applied.
R ¹⁰ 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. (N-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, n-dodecyl group, benzyl group, etc. may be mentioned), and particularly preferred is substitution of 6 to 12 carbon atoms or 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 (4) can be synthesized by a known method described in JP-A-11-12219.
Specific examples of the compound represented by the general formula (4) (compounds UV-101 to UV-121) are shown below, but the present invention is not limited to the following specific examples.

  In the present invention, a compound containing a cyano group may be used as the wavelength dispersion adjusting agent. As the compound containing a cyano group, a compound represented by the general formula (5) is preferably used.

General formula (5):

(In the general formula (5), Q ¹ and Q ² each independently represents an aromatic ring. X ¹ and X ² represent a hydrogen atom or a substituent, and at least one of them represents a cyano group, a carbonyl group, a sulfonyl group. Represents a group or an aromatic heterocycle.)

The aromatic ring represented by Q ¹ and Q ² in the general formula (5) may be an aromatic hydrocarbon ring or an aromatic heterocycle. These may be monocyclic or may form a condensed ring with another ring.

[Film dimensional stability]
The dimensional stability of the cellulose ester film of the present invention is as follows: the dimensional change rate after standing for 240 hours under conditions of 50 ° C. and 90% RH (high humidity) and 24 hours under the conditions of 90 ° C. and 5% RH. In the case of standing (high temperature), the dimensional change rate is preferably 0.3% or less in both the MD direction (casting direction) and the TD direction (direction perpendicular to the casting direction). More preferably, it is 0 or more and 0.2% or less, and further preferably 0 or more and 0.15% or less. The difference between the MD direction and the TD direction is preferably 0.2% or less, more preferably 0 or more and 0.15% or less, and particularly preferably 0 or more and 0.1% or less. When any one of the dimensional stability exceeds 0.1%, the ratio of the dimensional change rate in the TD direction to the dimensional change rate in the MD direction is preferably 0.5 or more and 2.0 or less. More preferably, it is 0.7 or more and 1.4 or less, and particularly preferably 0.8 or more and 1.25 or less.
As a specific measurement method, two cellulose ester film samples 30 mm × 120 mm were prepared, humidity-controlled at 25 ° C. and 60% RH for 24 hours, and an automatic pin gauge (Shinto Kagaku Co., Ltd.) with 6 mmφ at both ends. Were punched at intervals of 100 mm to obtain the original punch spacing (L0). Punch interval size (L1) after one sample was treated at 50 ° C. and 90% RH for 240 hours, punch after one sample was treated at 90 ° C. and 5% RH for 24 hours The distance dimension (L2) was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 60 ° C. and 90% RH (high humidity) = {| L0−L1 | / L0} × 100, Dimensional change rate of 90 ° C. and 5% RH (high temperature) = {| L0−L2 | / L0} × 100, and the dimensional change rate (MD direction and TD direction) was obtained.

[Hygroscopic expansion coefficient of film]
The hygroscopic expansion coefficient of the cellulose ester film of the present invention is preferably 30 × 10 ⁻⁵ /% RH or less in both the MD direction and the TD direction. Moreover, the one where the difference of MD direction and TD direction is smaller is preferable, and it is preferable to set it as 10x10 < ^-5 > /% RH or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. The difference in the hygroscopic expansion coefficient between the MD direction and the TD direction is preferably 0 or more and 5 × 10 ⁻⁵ /% RH or less, and more preferably 0 or more and 3 × 10 ⁻⁵ /% RH or less. Further, the hygroscopic expansion coefficient is preferably small, but usually a value of 1.0 × 10 ⁻⁵ /% RH or more. The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. By adjusting this hygroscopic expansion coefficient, it is possible to prevent frame-like transmittance increase, that is, light leakage due to distortion.
The hygroscopic expansion coefficient was determined as follows. Prepare two cellulose ester film samples 30mm x 120mm, adjust the humidity for 24 hours at 25 ° C and 60% RH, and open 6mmφ holes at both ends with automatic pin gauge (Shinto Kagaku Co., Ltd.) at 100mm intervals. The original punch spacing (L0). After one sample was conditioned at 25 ° C. and 80% RH for 4 hours, the punch interval dimension (L1) was measured, and the other sample was treated at 25 ° C. and 20% RH for 24 hours. The dimension (L2) of the punch interval was measured. Measurement was made to a minimum scale of 1/1000 mm at all intervals. Dimensional change rate of 25 ° C. and 80% RH (high humidity) = {| L0−L1 | / L0} × 100, Dimensional change rate of 25 ° C. and 80% RH (low humidity) = {| L0−L2 | / L0} × 100 was determined and divided by a humidity difference of 60% (= 80% -20%) to obtain a hygroscopic expansion coefficient.

[Tear properties of film]
The tear strength of the cellulose ester film of the present invention is preferably 0.01 N or more in both the casting direction (MD) and the direction perpendicular to the direction (TD) at 25 ° C. and 60% RH. The ratio of the tear strength in the TD direction to the strength is preferably from 0.7 to 1.4. More preferably, each tear strength is 0.015 N or more. A more preferable range is a tear strength ratio of 0.8 to 1.25, particularly preferably 0.9 to 1.1. Although it is preferable that the tear strength is large, the value is usually 1.0 N or less.
The tear strength can be measured by a tear strength measurement method (Elmendorf tear method) based on the tear test method of JISK7128-2: 1998. Specifically, it can be measured using a light load tear strength tester after conditioning a sample piece of 50 mm × 64 mm under the conditions of 25 ° C. and 65% RH for 2 hours.

[Curl characteristics of film]
The curl value of the cellulose ester film of the present invention is preferably -21 to + 21 / m in both the MD direction and the TD direction in the entire temperature and humidity range 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.
Moreover, it is preferable that the curl of the cellulose ester film of the present invention does not change with temperature and humidity.

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 outside the above range, the handling of the film may be hindered, and troubles may occur that cause the film to be cut. In addition, at the edge or center of the film, the film is strongly contacted with the transport roll, so it is easy to generate dust, and foreign matter adhesion on the film increases, and as an optical film such as an optical compensation film, scratches, The frequency of point defects and coating lines may exceed the allowable value. 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 200 μm, more preferably 30 to 120 μm, further preferably 40 to 80 μm, and particularly preferably 65 to 75 μm. The thickness of the film is preferably uniform. If there is unevenness in thickness, alignment film attachment and optical anisotropic layer attachment will not be performed uniformly, and sufficient functionality will often not be exhibited. Acceptable thickness unevenness is 3 μm or less from the center value, more preferably Is 2 μm or less, more preferably 1 μm or less.

  Moreover, it is preferable that the width | variety of the cellulose-ester film of this invention is 600 mm or more, More preferably, it is 1000 mm or more, More preferably, it is 1300 mm or more and 4000 mm or less. By setting it as the said range, the film which has favorable performance can be manufactured stably, and it can supply at low price.

(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 4.0% or less. It is more preferably 0.1 to 2.5%, and particularly preferably 1 to 2%. If the equilibrium moisture content is greater than 3%, the dependence of retardation on humidity changes becomes too great 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 was 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, 120 g / m ² · 24 h or more, 1500 g / m ² · 24h or less is preferable. More preferably 250~1200g / m ² · 24h, and particularly preferably 400~1000g / m ² · 24h. If it exceeds 1500 g / m ² · 24h, the absolute value of the humidity dependence of the Re value and Rth value of the film tends 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 tends to exceed 0.3 nm /% RH. It becomes unpreferable. When this optical compensation film or polarizing plate is incorporated in a liquid crystal display device, there is a possibility of causing a change in color or a decrease in viewing angle. In addition, when the moisture permeability of the cellulose ester film is less than 120 g / m ² · 24 h, when the polarizing plate is prepared by sticking to both surfaces of the polarizing film, the cellulose ester film prevents the adhesive from drying, resulting in poor adhesion. Arise.
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 was obtained as (water 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.) calculated the amount of water per unit area (g / m ² ) according to JIS Z-0208, and determined moisture permeability = mass after humidity adjustment−mass before humidity adjustment.

(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%. Since the cellulose ester film of the present invention is used for optical applications, the transparency of the film is important as an optical film. The haze was measured by measuring a 40 mm × 80 mm cellulose ester film sample of the present invention at 25 ° C. and 60% RH with a haze meter (HGM-2DP, Suga Test Instruments) according to JIS K-6714.

[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 thickness direction within a desired range. For example, in addition to the above-mentioned retardation reducing agent (compound that reduces optical anisotropy) and wavelength dispersion adjusting agent, other optical property adjusting agents, ultraviolet ray preventing agents, plasticizers, deterioration preventing agents, fine particles, and the like can be mentioned.
Various additives are added during the manufacturing stage. Although the time to add is not specifically limited, When forming a cellulose-ester film by heat-melting a thermoplastic resin, it can add at the time of heat-melting. Moreover, when forming into a film by solution film forming (solvent cast method) from the solution which melt | dissolved the polymer uniformly in the solvent, it can add to the preparation process of a polymer solution (henceforth 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 can contain 0.3% by mass or more, preferably 0.3% by mass or more and 45% by mass or less of an additive. 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 compounds that reduce optical anisotropy, wavelength dispersion regulators, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, release agents, infrared absorbers, etc. 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 less than 0.3% by mass, the properties of the base resin material alone are likely to appear, and for example, the optical performance and physical strength are likely to fluctuate with changes in temperature and humidity. There's a problem. When the total amount of these compounds exceeds 45% by mass, the compound is incompatible with the cellulose ester film, and problems such as precipitation on the film surface and clouding of the film (crying from the film) are likely to occur. Become.

[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 mass% or more, and the cellulose ester film has a thickness. In the region divided into 10 equal parts in the direction, the additive amount of each of the eight regions excluding the outermost layer is the average additive amount of the whole cellulose ester film (the value obtained by dividing the total amount of additives in the film by 10). 80% to 120%. 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 cellulose ester film of the present invention 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. And 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 is a description of a cellulose acylate dope solution containing 0.1 to 10% by mass with respect to 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.

[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, there is a method in which a fine particle dispersion prepared by stirring and mixing a solvent and fine particles is prepared in advance, and the fine particle dispersion is added to a small amount of a separately prepared cellulose ester solution, stirred and dissolved, and further mixed with the main cellulose ester dope solution. . 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 optical anisotropy, wavelength dispersion adjusting agents, etc., the cellulose ester film of the present invention has various additives (for example, plasticizers, UV inhibitors, etc.) in each preparation step. , Degradation inhibitors, infrared absorbers, etc.), which may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing materials having melting points of 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.

<solvent>
The cellulose ester according to the present invention is dissolved in a solvent, and is preferably formed by a solvent casting method in which the solvent is evaporated after extrusion or casting when cast on a substrate to form a film. These solvents are preferable, and do not dissolve the casting substrate. Two or more solvents may be mixed and used.

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

  Examples of good solvents include acetone, such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethers such as tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, Esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl sulfoxide, sulfolane, nitroethane 1,3-dioxolane, THF, methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferable.

  The dope preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. After casting the dope on the metal support, the solvent starts to evaporate and the alcohol ratio increases, so that the web (referred to as the dope film after casting the cellulose derivative dope on the support is called web )), And it is used as a gelling solvent to make the web strong and easy to peel off from the metal support. When these ratios are small, the dissolution of cellulose derivatives of non-chlorine organic solvents is promoted. There is also a role to suppress gelation, precipitation, and viscosity increase of the reactive metal compound.

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

  The most preferable solvent for dissolving the cellulose ester according to the present invention, which is a preferable polymer compound that satisfies such conditions, is a mixed solvent having a ratio of methylene chloride: ethyl alcohol of 95: 5 to 80:20. .

[Manufacturing process of cellulose ester film]
(Dissolution process)
The method for dissolving the cellulose ester solution (dope) in the present invention is not particularly limited, and it may be room temperature, or a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding the preparation of the cellulose ester solution in the present invention, as well as the solution concentration and filtration steps involved in the dissolution step, the Technical Report of the Invention Association (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association) The manufacturing processes described in detail on pages 22 to 25 are preferably used.

(Casting process)
Next, the manufacturing method of the film using the cellulose-ester solution in this invention is described. The method and equipment for producing a cellulose ester film in the present invention can use a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film. The dope (cellulose ester solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support.
The step of casting on the support is preferably covered with a certain space and a nitrogen atmosphere. The optimum temperature can be selected depending on the film forming method. The amount of residual solvent contained in the web at the time of peeling defined by the following formula (III) varies depending on the casting method. % Is preferable, 45% to 75% is more preferable, and 50% to 70% is most preferable. In the cooling casting method in which the dope surface temperature is set to 10 ° C. or less, the casting is preferably 100% to 300%, more preferably 130% to 270%, and most preferably 150% to 250%. preferable. The cooling casting can be performed, for example, by the method disclosed in JP-A-62-115035.
Formula (III): Residual solvent amount at stripping (%) = (film weight at stripping−film weight at zero residual solvent amount) / film mass at zero residual solvent amount × 100

(Drying process)
In the production method of the present invention, both ends in the width direction of the web obtained in the casting step are held, and the tenter's expansion / contraction width and temperature are adjusted so that tension can be applied, followed by conveyance and drying (note that the tenter is The section that holds both ends of the direction is called the tenter section). The tenter shape is not particularly limited as long as it satisfies the claims of the present invention, and a method of applying tension by holding both ends of the film with clips, a method of fixing both ends of the film with pins, and the like can be used.
In the cellulose ester film of the present invention, the tenter tension is adjusted to 3 to 10 kgf / m (29 to 98 N / m). It is more preferably 4 to 9 kgf / m (39 to 88 N / m), and most preferably 5 to 8 kgf (49 to 78 N / m). If it exceeds 10 kgf / m (98 N / m), even in the prescription of the present invention, the slow axis angle is parallel or perpendicular to the casting direction, which is not preferable because it is difficult to balance the mechanical characteristics of the problem. On the other hand, if it is less than 3 kgf / m (29 N / m), the thickness unevenness is increased, and the mechanical properties are likely to be uneven, which is not preferable.
In general, in the process at the initial stage of drying, the solvent is volatilized and thus shrinkage occurs. Therefore, if the tension is applied, the tenter width may be narrower than the width of the tenter entrance. The expansion / contraction width of the tenter is preferably 80% to 110%, more preferably 85% to 107%, most preferably 87% to 105%, where the width of the tenter entrance is 100%. preferable. Since the drying temperature of the tenter part varies depending on the casting method, an optimal temperature is appropriately selected. In the case of a normal casting method, the temperature is preferably 70 ° C to 140 ° C, more preferably 80 ° C to 130 ° C, and most preferably 90 ° C to 120 ° C. When the cooling casting method is used, it is preferably 40 ° C. to 130 ° C., more preferably 40 ° C. to 120 ° C., and most preferably 50 ° C. to 115 ° C. The temperature may be set with a gradient in the length direction of the tenter part. Although there is no restriction | limiting in particular in the heating method, The method of introduce | transducing the wind set to predetermined temperature into a tenter part is used preferably. Moreover, in order to reduce the variation in temperature in the surface, a wind control plate may be provided, or a known method such as using a back heater in combination can be used.

  The residual solvent amount when applying tension with a tenter is preferably 5% or more. It is more preferably 10% or more, and most preferably 15% or more. When tension is applied with a residual solvent amount of 5% or less, the retardation may not be reduced to a desired range.

The cellulose ester film of the present invention may be held in the tenter until the residual solvent amount becomes zero as much as possible, but from the viewpoint of productivity, the film is detached from the tenter during drying and both ends held by the tenter clip. After cutting off, it is desirable to finish drying while mechanically transporting by a drying section comprising a plurality of roll groups. “To finish drying” may be any residual solvent amount of 1% or less. The amount of residual solvent in the film when detached from the tenter is preferably 15% or more and 40% or less, more preferably 17% or more and 37% or less, and most preferably 17% or more and 35% or less. When peeling from the tenter while maintaining a residual solvent amount exceeding 40%, the film is easily stretched in the length direction of the film with the necessary transport tension for the subsequent drying process, and adjustment to achieve the desired optical performance is achieved. It becomes difficult. Further, in order to lower it to less than 15%, it is necessary to slow the conveying speed or lengthen the tenter part, which is not desirable in terms of productivity.
In the above drying step, in a section where the film residual solvent amount is 15% or more, the conveying tension is preferably 1 kgf / m to 20 kgf / m (9.8 N / m to 196 N / m) per film width, and 2 kgf / m to 18 kgf. / M (19.6 N / m to 176 N / m) is more preferable, and 3 kgf / m to 16 kgf / m (29.4 N / m to 167 N / m) is most preferable. If it is less than 1 kgf / m (19.6 N / m), film sagging, wrinkles, roll-like rubbing and the like are likely to occur, and the surface state deteriorates. If it exceeds 20 kgf / m (196 N / m), particularly when the amount of residual solvent is large, it is difficult to achieve the target optical performance by stretching in the transport direction.

  The drying temperature after releasing the holding of both ends of the film is preferably from 100 to 150 ° C, more preferably from 100 ° C to 140 ° C, and most preferably from 110 ° C to 140 ° C. When the temperature is lower than 100 ° C., it is difficult to proceed with drying, and at the same time, it is difficult to reduce Rth. On the other hand, when the temperature exceeds 150 ° C., the glass transition temperature of the film is often exceeded, and the film may be stretched in the length direction to cause a phase difference. Further, depending on the type of additive, there is a possibility that it will be slightly volatilized in the drying system. Here, the drying temperature is the temperature when a sensor such as a thermocouple is attached to the film being dried, but when using the method of introducing heated air to dry, the temperature of the air supply port and the exhaust port Management by temperature In general, the supply air temperature is higher than the membrane surface temperature, and the exhaust temperature is equal to or slightly lower than the membrane surface temperature. When a method of heating using radiant heat is used, measurement is performed using a fixed sensor near the film surface.

The film after drying is wound up to a predetermined length in a roll by a winder. You may provide the curl improvement part etc. by steam immediately before winding.
In the solution casting film forming method used for the functional protective film which is an optical member for an electronic display which is the main use of the cellulose ester film in the present invention, in addition to the solution casting film forming apparatus, the undercoat layer In many cases, a coating apparatus is added for surface processing of a film such as an antistatic layer, an antihalation layer, or a protective layer. These are described in detail on pages 25 to 30 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention), and can be preferably used as appropriate in the present invention. it can.

  The residual solvent amount of the cellulose ester film produced as described above is preferably 3% or less, more preferably 2% or less, and most preferably 1% or less.

[Application (Polarizing plate)]
The use of the cellulose ester film of the present invention will be described.
The cellulose ester film of the present invention is particularly useful for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. There is a method in which the obtained cellulose ester film is alkali-treated, and a polarizing film prepared by immersing and stretching the polyvinyl alcohol film in an iodine solution is bonded to both surfaces using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.
Examples of the adhesive used to bond the protective film treated surface and the polarizing film include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like.
The polarizing plate is composed of a polarizing film and a protective film for protecting both surfaces of the polarizing film, and further comprises a protective film on one surface of the polarizing plate and a separate film on 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.
In a liquid crystal display device, a substrate containing a liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate protective film to which the cellulose ester film of the present invention is applied can provide excellent display properties regardless of the location. It is done. In particular, the polarizing plate protective film on the display side outermost surface of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflective layer, and the like.

[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 in 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 film, and the like. The optical compensation film has birefringence 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. The cellulose ester film of the present invention can control optical anisotropy by laminating another optically anisotropic film or optically anisotropic layer having another birefringence.

Therefore, when the cellulose ester film of the present invention is used as an optical compensation film of a liquid crystal display device, Re _{(590) of} the optically anisotropic film or optically anisotropic layer used in combination is 0 to 200 nm, and | Rth ₍₅₉₀₎ | Is preferably 0 to 400 nm, and any optically anisotropic layer may be used within this range. 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, page 111 (1981); edited by the Chemical Society of Japan). , Quarterly Chemistry Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985). J. Zhang et al., J. Am.Chem.Soc., Vol.116, page 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), polycarbonate, polyarylate, polysulfone, polyvinyl alcohol, polymethacrylic acid ester, polyacrylic acid ester and cellulose ester (eg, cellulose triacetate). Tate, 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 by grasping both sides of the polymer film and stretching in the width direction, or biaxial stretching by combining 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.

  Further, as the polymer film forming the optically anisotropic layer, at least one polymer material selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide polyesterimide, and polyaryletherketone is used. A method in which a solution in which is dissolved in a solvent is applied to a substrate and the solvent is dried to form a film can also be preferably used. At this time, a method of stretching the polymer film and the base material to develop optical anisotropy and using it as an optical anisotropic layer can be preferably used, and the cellulose ester film of the present invention is preferably used as the base material. be able to. In addition, the above polymer film is prepared on another substrate, and after the polymer film is peeled off from the substrate, it is bonded to the cellulose ester film of the present invention and used together as an optically anisotropic layer. Is also preferable. In this method, the thickness of the polymer film can be reduced, and is preferably 50 μm or less, and more preferably 1 to 20 μm.

[Usage (Liquid Crystal Display)]
In general, a liquid crystal display device includes a liquid crystal cell in which liquid crystal is supported between two electrode substrates, and at least one polarizing plate made of a polarizing film and at least one protective film. is there. In the liquid crystal display device, it is preferable that at least one optical compensation film is disposed between the liquid crystal cell and the polarizing film, and the cellulose ester film of the present invention is used as a protective film for the polarizing film and a support for the optical compensation film. Can be used. When the cellulose ester film of the present invention is used as a support for an optical compensation film, the transmission axis of the polarizing film and the slow axis of the optical compensation film provided with the cellulose ester may be arranged at any angle. .
Note that the liquid crystal layer of the liquid crystal cell used in the liquid crystal display device of the present invention is usually formed by enclosing 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. Among them, the liquid crystal mode is preferably an IPS system.

(TN type liquid crystal display device)
The cellulose ester film of the present invention may be used as a support for an optical compensation film of a TN liquid crystal display device having a TN mode liquid crystal cell or as a protective film for a polarizing plate. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation film used in the TN liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068). is there.

(STN type liquid crystal display)
You may use the cellulose-ester film of this invention as a support body of the optical compensation film of a STN type liquid crystal display device which has a liquid crystal cell of STN mode, or a protective film of a polarizing plate. 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 film used for the STN type liquid crystal display device is described in JP-A No. 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 film of a VA liquid crystal display device having a VA mode liquid crystal cell. It is also used as a protective film for polarizing plates. It is preferable that Re of the optical compensation film used for the VA liquid crystal display device is 0 to 150 nm and Rth is 70 to 400 nm. Re is more preferably 20 to 70 nm. When two optically anisotropic polymer films are used for the VA liquid crystal display device, the Rth value of the film is preferably 70 to 250 nm. When one optically anisotropic polymer film is used for the VA liquid crystal display device, the Rth 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 film 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 the improvement of the color tone, the expansion of the viewing angle, and the improvement of the contrast. In this aspect, the cellulose ester film of the present invention is applied to the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate among the polarizing plate protective films disposed above and below the liquid crystal cell. It is preferable to use the polarizing plate used on at least one side. More preferably, an optically anisotropic layer is disposed between the protective film of the polarizing plate and the liquid crystal cell, and the retardation value of the disposed optically anisotropic layer is twice the value of Δn · d of the liquid crystal layer. It is preferable to set as follows.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The cellulose ester film of the present invention is also advantageous as a support for an optical compensation film or a protective film for a polarizing plate 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. Used. In the optical compensation film 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 film or in the normal direction. The optical properties of the optical compensation film used in the OCB type liquid crystal display device or HAN type liquid crystal display device are also the optical properties of the optically anisotropic layer, the optical properties of the support, and the arrangement of the optically anisotropic layer and the support. Determined by. An optical compensation film 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 a paper by 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 an optical compensation film for TN type, STN type, HAN type and GH (Guest-Host) type reflective liquid crystal display devices. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. The optical compensation film used for the reflection type 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 film of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (Axial Symmetrical Microcell) mode or as a protective film for a polarizing plate. 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., SID 98 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 be preferably used.

(Photo film support)
Furthermore, the cellulose ester film of the present invention can be applied as a support for silver halide photographic light-sensitive materials, and various materials, formulations and processing methods described in the patent can be applied. Regarding these techniques, Japanese Patent Application Laid-Open No. 2000-105445 details the color negative, and the cellulose ester film of the present invention is preferably used. Further, application as a support for a color reversal silver halide photographic light-sensitive material is also preferable, and various materials, formulations and processing methods described in JP-A No. 11-282119 can be applied.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
(Preparation of cellulose acylate solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution A.

[Composition of cellulose acylate solution A]
Cellulose acylate having a degree of acetylation of 2.92 100.0 parts by mass Methylene chloride (first solvent) 380.0 parts by mass Methanol (second solvent) 60.0 parts by mass

(Preparation of matting agent solution A)
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 to prepare a matting agent solution A.

[Composition of matting agent solution A]
-Silica particle dispersion liquid with an average particle diameter of 16 nm 10.0 parts by mass-Methylene chloride (first solvent) 76.3 parts by mass-Methanol (second solvent) 3.4 parts by mass-Cellulose acylate solution A 10.3 parts by mass Part

(Preparation of additive solution A)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The following compounds were used as the compound that reduces the optical anisotropy and the wavelength dispersion adjusting agent.

(Additive solution A composition)
-50.0 parts by mass of the following retardation-reducing compound
・ 5.0 parts by mass of the following wavelength dispersion adjusting agent
・ Methylene chloride (first solvent) 58.5 parts by mass
-Methanol (second solvent) 8.7 parts by mass
-Cellulose acylate solution A 12.8 parts by mass

(Preparation of cellulose acylate film 1)
93.0 parts by mass of the cellulose acylate solution A, 1.4 parts by mass of the matting agent solution A, and 5.6 parts by mass of the additive solution A were mixed after filtration, and a band casting machine was used. And cast. In the composition, the mass ratio of the retardation reducing compound and the wavelength dispersion adjusting agent to cellulose acylate was 12.0% and 1.2%, respectively.
The film was peeled off from the band with a residual solvent amount of 55%, and dried at 90 to 110 ° C. while applying a tension of 8 kgf / m (78 N / m) in a tenter zone where both ends of the film were held by clips. At this time, the maximum expansion / contraction ratio with respect to the tenter entrance was 100%. When the residual solvent amount was 15 to 20%, the film was removed from the tenter clip, and the end was cut off with a cutter blade. Next, the film was dried while being transported to a drying zone composed of a plurality of roll groups with a transport tension of 10 kgf / m (98 N / m). The drying temperature was 100 ° C to 135 ° C. After cutting both ends of the obtained film with a cutter blade to make a width of 720 mm, a knurling for preventing winding deviation was provided at both ends, and a 2600 m length was wound up in a roll shape to produce a cellulose acylate film 1. As a result of investigating the residual solvent amount of the obtained film, it was 0.2%. The film thickness was 80 μm.
From the obtained film, a sample of 6 cm × 4 cm was cut out from a total of 17 locations, 2% from the center and 2% from the right and left ends as viewed from the casting direction, and 8 parts between them, respectively. The angle between the direction of the phase axis and the casting direction was measured, and the maximum and minimum values and the average value of 17 points are shown in Table 1. Further, the thickness, Re (590), Rth (590), dimensional change rate, and tear strength were measured by the methods described in the above section (Method for evaluating cellulose acylate). The results are shown in Table 1.

[Example 2]
(Preparation of cellulose acylate film 2)
The dope produced in Production Example 1 was used for casting with a band casting machine. After peeling off the film with a residual solvent amount of 70%, the film was dried at 90 to 110 ° C. while applying a tension of 9 kgf / m (88 N / m) in a tenter zone where both ends of the film were held with clips. A cellulose acylate film 2 was produced in the same manner as in Production Example 1 except that the residual solvent amount was released from the tenter at a stage of 20 to 25% and the conveying tension was 10 kgf / m (98 N / m). As a result of examining the residual solvent amount of the obtained film, it was 0.4%. The film thickness was 80 μm.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

[Example 3]
(Preparation of cellulose acylate film 3)
The flow rate of the dope used in Production Example 1 was adjusted, and casting was performed such that the film thickness of the obtained film was 70 μm. After peeling off the film with a residual solvent amount of 65%, the film was dried at 90-110 ° C. while applying a tension of 9 kgf / m (88 N / m) in a tenter zone where both ends of the film were held with clips. Cellulose acylate film in the same manner as in Production Example 1 except that the solvent was removed from the tenter when the residual solvent amount was 20 to 25%, the conveyance tension was 9 kgf / m (88 N / m), and the winding length was 3000 m. 3 was produced. As a result of investigating the residual solvent amount of the obtained film, it was 0.2%.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

[Example 4]
(Preparation of cellulose acylate film 4)
The flow rate of the dope used in Production Example 1 was adjusted, and the resulting film was cast so that the film thickness was 65 μm. After peeling off the film with a residual solvent amount of 60%, the film was dried at 90 to 110 ° C. while applying a tension of 8 kgf / m (78 N / m) in a tenter zone where both ends of the film were held with clips. Cellulose acylate film in the same manner as in Production Example 1 except that the solvent was removed from the tenter when the residual solvent amount was 18 to 23%, the conveyance tension was 10 kgf / m (98 N / m), and the winding length was 3200 m. 4 was produced. As a result of examining the residual solvent amount of the obtained film, it was 0.1%.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

[Example 5]
(Preparation of cellulose acylate film 5)
The flow rate of the dope used in Production Example 1 was adjusted, and casting was performed such that the film thickness of the obtained film was 40 μm. After peeling off the film with a residual solvent amount of 50%, the film was dried at 95-110 ° C. while applying a tension of 6 kgf / m (59 N / m) in a tenter zone where both ends of the film were held with clips. Cellulose acylate film in the same manner as in Production Example 1 except that the solvent was removed from the tenter when the residual solvent amount was 18 to 23%, the conveyance tension was 8 kgf / m (78 N / m), and the winding length was 3900 m. 5 was produced. As a result of examining the residual solvent amount of the obtained film, it was 0.1%.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

[Example 6]
(Preparation of cellulose acylate film 6)
A cellulose acylate film 6 was produced in the same manner as in Production Example 1 except that the finished width of the film was adjusted to 1475 mm. As a result of examining the residual solvent amount of the obtained film, it was 0.1%. The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.

[Example 7]
(Preparation of cellulose acylate film 7)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution B.

[Composition of cellulose acylate solution B]
-Acetylation degree 2.95 cellulose acylate 100.0 parts by mass-Methylene chloride (first solvent) 380.0 parts by mass-Methanol (second solvent) 60.0 parts by mass

(Preparation of matting agent solution B)
A matting agent solution B was prepared in the same manner as in the preparation of the matting agent solution A in Example 1, except that the cellulose acylate solution A was changed to the cellulose acylate solution B.

(Preparation of additive solution B)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and an additive solution B was prepared. The same compounds as in Production Example 1 were used as the retardation reducing compound and the wavelength dispersion adjusting agent.

[Additive solution B composition]
-Retardation-reducing compound 80.0 parts by mass-Wavelength dispersion adjusting agent 8.0 parts by mass-Methylene chloride (first solvent) 58.5 parts by mass-Methanol (second solvent) 8.7 parts by mass-Cellulose acetate Solution B 12.8 parts by mass

93.0 parts by mass of the cellulose acetate solution B, 1.4 parts by mass of the matting agent solution B, and 5.6 parts by mass of the additive solution B were mixed after filtration, and a band casting machine was used. And cast. In the composition, the mass ratio of the retardation reducing compound and the wavelength dispersion adjusting agent to cellulose acetate was 15.6% and 1.2%, respectively.
The produced dope was cast with a band casting machine. After peeling off the film with a residual solvent amount of 45%, the film was dried at 100-120 ° C. while applying a tension of 9.5 kgf / m (93 N / m) in a tenter zone where both ends of the film were held with clips. A cellulose acylate film 7 was produced in the same manner as in Production Example 1 except that the residual solvent amount was 15-18% and the carrier was separated from the tenter and the conveyance tension was 9.3 kgf / m (93 N / m). As a result of investigating the residual solvent amount of the obtained film, it was 0.2%. The film thickness was 80 μm.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1. The results are shown in Table 1.
The slow axis at each measurement location of the cellulose ester film of the present invention is generally in the direction perpendicular to the casting direction, and each measured value is between 80-90 ° and −90-82 °, The angle formed by the phase axes was a maximum of 18 °, the average direction was 89 °, and the standard deviation (dispersion value) was 5.7 °.

[Comparative Example 1]
(Preparation of cellulose acylate film 8)
A cellulose acylate film 8 was produced in the same manner as in Example 3 except that the tension in the width direction of the tenter was 13 kgf / m (127 N / m). The thickness was 65 μm. About the obtained film, it carried out similarly to Example 1, and evaluated optical performance. The results are shown in Table 1.

[Comparative Example 2]
(Preparation of cellulose acylate film 9)
A cellulose acylate film 9 was produced in the same manner as in Production Example 3 except that the tension in the width direction of the tenter was 1.8 kgf / m (17.6 N / m). The average thickness was 65 μm, but the maximum thickness was 69 μm and the minimum thickness was 61 μm. In addition, the breakage trouble occurred 5 times during 2600 m100 roll production. About the obtained film, it carried out similarly to Example 1, and evaluated optical performance. The results are shown in Table 1.

[Comparative Example 3]
(Preparation of cellulose acylate film 10)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution H.

[Cellulose acylate solution H composition]
Cellulose acylate having an acetylation degree of 2.84 100.0 parts by mass Triphenyl phosphate 7.8 parts by mass Biphenyl diphenyl phosphate 3.9 parts by mass Methylene chloride (first solvent) 400.0 parts by mass Methanol ( Second solvent) 60.0 parts by mass

(Preparation of matting agent solution H)
A matting agent solution H was prepared in the same manner as in the preparation of the matting agent solution H in Example 1, except that the cellulose acylate solution A was changed to the cellulose acylate solution H.

  98.6 parts by mass of the cellulose acylate solution H and 1.4 parts by mass of the matting agent solution H were mixed after filtration, and cast using a band casting machine in the same manner as in Example 1. A cellulose acylate film 10 was produced. About the obtained film, it carried out similarly to Example 1, and evaluated optical performance. The results are shown in Table 1.

[Example 8]
(Preparation of cellulose acylate film 11)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acylate solution C. At this time, the cellulose acylate having a total substitution degree of 2.77 (acetyl substitution degree 2.04 + propynyl substitution degree 0.73) was used.

[Cellulose acylate solution C composition]
Cellulose acylate 100 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass

(Preparation of matting agent solution C)
A matting agent solution C was prepared in the same manner as in the preparation of the matting agent solution A in Example 1, except that the cellulose acylate solution A was changed to the cellulose acylate solution C.

(Preparation of additive solution C)
A compound having the following composition was charged into another mixing tank and stirred while heating to dissolve each component to prepare an additive solution. The same compounds as in Example 1 were used as the retardation reducing compound and the wavelength dispersion adjusting agent.

[Additive solution C composition]
-Retardation-reducing compound 50 parts by mass-Wavelength dispersion adjusting agent 5 parts by mass-Methylene chloride (first solvent) 82 parts by mass-Methanol (second solvent) 15 parts by mass-1-butanol (third solvent) 3 parts by mass Parts ・ Cellulose acetate solution C 12 parts by mass

  A cellulose acylate film 11 having a thickness of 40 μm was prepared in the same manner as in Example 5 by adding 5 parts by weight of the matting agent solution C and 40 parts by weight of the additive solution C to 465 parts by weight of the cellulose acylate solution C. . About the obtained film, it carried out similarly to Example 1, and evaluated optical performance. The results are shown in Table 1.

[Example 9]
(Preparation of cellulose acylate film 12)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution D was prepared.

[Cellulose acylate solution D composition]
100 parts by mass of cellulose acetate having a substitution degree of 2.94
Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass

(Preparation of matting agent solution D)
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. The dispersion was charged into a disperser together with the following composition, and further stirred for 30 minutes or more to dissolve each component to prepare a matting agent solution D.

[Composition of matting agent solution D]
-Silica particle dispersion liquid with an average particle diameter of 16 nm 10.0 parts by mass-Methylene chloride (first solvent) 75.6 parts by mass-Methanol (second solvent) 3.4 parts by mass-1-butanol (third solvent) 0 0.7 parts by mass-cellulose acylate solution D 10.3 parts by mass

(Preparation of additive solution D)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The compound of Example 1 was used as the compound that lowers the optical anisotropy and the wavelength dispersion adjusting agent.

(Additive solution D composition)
-Retardation-reducing compound 54.0 parts by mass-Wavelength dispersion modifier 6.0 parts by mass-Methylene chloride (first solvent) 60.0 parts by mass-Methanol (second solvent) 9.0 parts by mass-1-butanol ( Third solvent) 0.5 parts by mass / cellulose acylate solution D 12.5 parts by mass

The dope was prepared by sufficiently stirring 92.5 parts by mass of the cellulose acylate solution D, 0.5 parts by mass of the matting agent solution D, and 7.0 parts by mass of the additive solution D after filtration. The dope was cast from a casting port onto a drum cooled to -10 ° C.
Peel from the drum with a residual solvent amount of 180%, and dry while gradually increasing the temperature from 40 to 120 ° C while applying a tension of 7 kgf / m (69 N / m) in a tenter zone where both ends of the film are held by multiple pins. I let you. At this time, the maximum expansion / contraction ratio with respect to the tenter entrance was 98%. When the residual solvent amount was 27%, the film was removed from the pin tenter, and the edge was cut off with a cutter blade. Next, the film was dried while being transported to a drying zone composed of a plurality of roll groups with a transport tension of 10 kgf / m (98 N / m). The drying temperature was 120 ° C to 148 ° C. After cutting the both ends of the obtained film with a cutter blade to obtain a width of 1340 mm, a knurling for preventing winding deviation was provided at both ends, and a 2600 m length was wound up in a roll shape to prepare a cellulose acylate film 12. As a result of examining the residual solvent amount of the obtained film, it was 0.5%. The film thickness was 65 μm.
The optical performance of the obtained film was evaluated in the same manner as in Production Example 1.
The slow axis at each measurement location of the cellulose ester film of the present invention is generally in a direction perpendicular to the casting direction, and each measured value is between 77 to 90 ° and −90 to −73 °, The angle formed by the slow axis was 30 ° at the maximum, the average direction was −87.8 °, and the standard deviation was 8.5 °. The results are shown in Table 1.

As shown in Table 1, the films 1 to 7 and 11 and 12 as examples of the present invention have small in-plane retardation and retardation in the film thickness direction, and the angle formed between the slow axis and the casting direction. Is different by 10 ° or more at an arbitrary position in the width direction. These show that the dimensional change is small, and the difference between the value in the TD direction and the value in the MD direction is small, and these are preferable films. It can also be seen that the tear strength is greater than 0.01 N, and the MD / TD ratio is close to 1 and is a preferred film with good balance.
On the other hand, the films 8 and 9 as comparative examples have no desired difference in the width direction between the slow axis and the casting direction, and the tear strength and dimensional stability are inferior. It turns out that troubles are likely to occur. Moreover, it turns out that the film 10 is not a preferable film with a large in-plane and film thickness direction retardation.

[Example 10]
[Preparation of retardation film 1]
To one side of the cellulose acylate film 1 produced in Example 1, 25 ml / m ² of a 1.5 mol / L potassium isopropyl alcohol solution was applied and dried at 25 ° C. for 5 seconds. The surface of the film was dried by washing with running water for 10 seconds and blowing air at 25 ° C. In this way, only one surface of the cellulose acylate film was saponified.

On the saponification surface of the cellulose acylate film, a coating solution having the following composition was applied at 28 ml / m ² with a # 16 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds. Next, the formed film was rubbed in a direction parallel to the longitudinal direction of the cellulose acylate film.

(Orientation film coating solution composition)
・ Denatured polyvinyl alcohol 10 parts by mass, water 371 parts by mass, methanol 119 parts by mass, glutaraldehyde (crosslinking agent) 0.5 part by mass

(Formation of optically anisotropic layer)
After rubbing the alignment film, 1.8 g of the following discotic (liquid crystalline) compound, 0.2 g of ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose acetate Butyrate (CAB551-0.2, Eastman Chemical Co., Ltd.) 0.04 g, Photopolymerization initiator (Irgacure 907, Ciba Geigy Co., Ltd.) 0.06 g, Sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) ) A coating solution prepared by dissolving 0.02 g in 8.43 g of methyl ethyl ketone was applied with a # 2.5 wire bar. Heated at 130 ° C. for 2 minutes to orient the discotic compound. Next, using a 120 W / cm high-pressure mercury lamp at 100 ° C., UV irradiation was performed for 1 minute to crosslink the discotic compound and fix the alignment state. Then, it stood to cool to room temperature, and produced the phase difference film 1. Note that Re ₍₅₉₀₎ of the optically anisotropic layer of the retardation film 1 was 30 nm, and | Rth ₍₅₉₀₎ | was 120 nm.

[Example 11]
[Preparation of Polarizing Plate 1]
The retardation film 1 obtained in Example 10 was immersed in a 1.5 mol / L aqueous sodium hydroxide solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing bath, and neutralized using 0.05 mol / L 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, the surface of the cellulose acylate film was saponified.
Next, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. Using the 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, the saponified retardation film 1 was bonded to a polarizer. A polarizing plate 1 was prepared by similarly bonding a saponified commercially available cellulose acetate film (TD80UF: manufactured by Fuji Photo Film) on the other surface of the polarizer.

[Example 12]
[Production of Polarizing Plate 2]
The cellulose acetate film 1 produced according to Example 1 was saponified in the same manner as in Example 11. On the other hand, a roll-like polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer. A saponified cellulose acetate film 1 was bonded to a polarizer using a 3% aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive. A saponified commercial cellulose acetate film was similarly bonded to the other surface of the polarizer, and an optical compensation film obtained by uniaxially stretching an Arton film (manufactured by JSR) was bonded to the surface of the cellulose acylate film 1 side. Thus, a polarizing plate 2 was produced. The in-plane retardation Re of the optical compensation film was 275 nm, the retardation Rth in the thickness direction was 0 nm, and the Nz factor was 0.5.

[Example 13]
[Preparation of Polarizing Plate 3]
A polarizing plate 3 was produced in the same manner as in Example 12 except that a commercially available cellulose acylate film (TFY80U, manufactured by Fuji Photo Film Co., Ltd.) was used instead of the cellulose acylate film 1.

[Example 14]
(Preparation of polarizing plate 4)
(Hard coat layer coating solution)
250 g of Desolite KZ-7869 (UV curable hard coat composition, 72% by mass, manufactured by JSR Corporation) was dissolved in a mixed solvent of 62 g of methyl ethyl ketone and 88 g of cyclohexanone to prepare a hard coat layer coating solution. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.53.

(Anti-glare coating solution)
91 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.), 199 g of Desolite KZ-7115, KZ-7161 (ZrO ₂ fine particle dispersion, manufactured by JSR Co., Ltd.) 52 g of methyl ethyl ketone / cyclohexanone was dissolved in a mixed solvent of 54/46% by mass. 10 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) was added to the obtained solution. The refractive index of the coating film obtained by applying this solution and curing with ultraviolet rays was 1.61. Further, 20 g of crosslinked polystyrene particles having an average particle size of 2.0 μm (SX-200H, manufactured by Soken Chemical Co., Ltd.) was added to this solution in a mixed solvent of 80 g of methyl ethyl ketone / cyclohexanone = 54/46 mass% at a high speed disperser at 5000 rpm. After adding and stirring 29 g of the dispersion that was stirred and dispersed for a period of time, it was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for the antiglare layer.

The above-mentioned hard coat layer coating solution was applied to a commercially available cellulose acetate film (Fuji Photo Film Co., Ltd.) using a bar coater, dried at 120 ° C., and then air-cooled metal halide lamp of 160 W / cm (eye graphics). Was used to cure the coating layer by irradiating it with ultraviolet rays having an irradiance of 400 mW / cm ² and an irradiation energy of 300 mJ / cm ² to form a hard coat layer having a thickness of 4 μm. Further, the antiglare layer coating solution is applied using a bar coater, dried at 120 ° C. in an oxygen concentration atmosphere of 0.01% or less by nitrogen purge, and then an air-cooled metal halide lamp (eye Using a graphics), the coating layer is cured by irradiating ultraviolet rays with an irradiance of 400 mW / cm ² and an irradiation energy amount of 300 mJ / cm ² to form an anti-glare hard coat layer having a thickness of 1.4 μm. Formed.

  A polarizing plate was produced by laminating the cellulose acylate film 1 of Example 1 on one side of the polarizer and the above cellulose acetate film provided with a hard coat layer and an antiglare layer on the other side. Furthermore, an adhesive sheet was pasted on the opposite side of the cellulose acylate film 1 from the polarizer, and an optical compensation film obtained by uniaxially stretching the Arton film (manufactured by JSR) used in Example 12 was pasted. Thus, a polarizing plate 4 was produced.

[Example 15]
(Production of liquid crystal display device)
A pair of polarizing plates and a pair of optical compensation sheets provided in a commercially available liquid crystal display device (manufactured by Hitachi, Ltd.) using an IPS liquid crystal cell were peeled off, and the liquid crystal cell was taken out.
A polarizing plate 2 was placed on one side of the liquid crystal cell so that the cellulose acylate film 1 was on the liquid crystal cell side, and a polarizing plate 3 was placed on the other side of the polarizing plate 2 of the liquid crystal cell to produce a liquid crystal display device. When the power of the liquid crystal display device thus manufactured was turned on and the viewing angle dependency of contrast and color at the time of black display and marginal display was visually observed, it had good viewing angle characteristics in all directions. .

[Example 16]
(Production of liquid crystal display device)
A polarizing plate 4 is arranged on one side of the liquid crystal cell taken out in Example 15 so that the cellulose acylate film 1 is on the liquid crystal cell side, and a polarizing plate 3 is arranged on the other side of the polarizing plate 4 of the liquid crystal cell to display a liquid crystal display. A device was made. The liquid crystal display device thus manufactured was turned on, and the viewing angle dependence of contrast and color at the time of black display and marginal display was visually observed, and it had good viewing angle characteristics in all directions. The display quality on the front was also sufficiently acceptable.

[Comparative Example 4]
A polarizing plate 5 was produced in the same manner as in Example 14 except that the cellulose acylate film 8 was used instead of the cellulose acylate film 1. A liquid crystal display device was produced in the same manner as in Example 16 except that the polarizing plate 5 was used instead of the polarizing plate 4. The liquid crystal display device thus manufactured was turned on and the viewing angle dependency of the contrast and color at the time of black display and white display was visually observed. As a result, the color change in the oblique direction was large and the display quality was poor. It was.

[Comparative Example 5]
A polarizing plate 6 was produced in the same manner as in Example 14 except that the cellulose acylate film 9 was used instead of the cellulose acylate film 1. A liquid crystal display device was produced in the same manner as in Example 16 except that the polarizing plate 6 was used instead of the polarizing plate 4. When the power source of the liquid crystal display device thus fabricated was turned on and the image quality during black display was visually observed, color interference due to light interference that appears to be caused by thickness unevenness occurred and display quality was poor.

Claims (13)

  A transparent film having a retardation value Rth (590) of −25 nm to 25 nm and an in-plane retardation value Re (590) of 0 nm to 10 nm at a wavelength of 590 nm. A cellulose ester film characterized in that the direction of the slow axis in the film plane differs by 10 ° or more at an arbitrary position in the width direction.   The cellulose ester film is characterized in that the average direction of the slow axis in the film plane at a wavelength of 590 nm is not separated by more than 20 ° from the casting direction or the direction perpendicular to the casting direction. The cellulose ester film described in 1.   The cellulose ester film according to claim 1 or 2, wherein the film width of the cellulose ester film is 600 mm or more. The cellulose ester film according to claim 1, wherein the degree of ester substitution (X + Y) of the cellulose ester film satisfies the following formula (I).
Formula (I) 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 cellulose ester film according to claim 1, comprising at least one compound that lowers the retardation Rth in the film thickness direction.   The dimensional change rate at 50 ° C. and 90% RH 240h in the casting direction and the direction perpendicular to the casting direction of the cellulose ester film is 0.3% or less, and the dimensional change rate in the casting direction is perpendicular to the casting direction. The cellulose ester film according to claim 1, wherein a difference in dimensional change rate in any direction is 0.2% or less.   Both the tear strength in the casting direction and the direction perpendicular to the casting direction of the cellulose ester film are 0.01 N or more, and the ratio of the tear strength in the TD direction to the tear strength in the MD direction is 0.7 or more and 1.4. It is the following, The cellulose-ester film in any one of Claims 1-6 characterized by the above-mentioned.   The cellulose ester film according to claim 1, wherein the cellulose ester film has a thickness of 30 to 200 μm.   A cellulose ester solution (hereinafter also referred to as a dope) is prepared, the dope is cast on a support, the cast film is peeled off as a film from the support, and both ends in the width direction of the peeled film are tenters (films). A method for producing a cellulose ester film which is held by a width direction gripping device) to hold the width of the film and is dried, and is further dried after being detached from the tenter, and grips both ends in the width direction of the film. In the tenter section, the tension applied in the film width direction is 3 kgf / m or more and less than 10 kgf / m, and in the section where the film residual solvent amount is 15% or more, the tension applied in the film transport direction is 1 kgf / m or more and 20 kgf / m. The cellulose s according to any one of claims 1 to 8, wherein Method of manufacturing a Rufirumu.   At least one sheet of the cellulose ester film according to any one of claims 1 to 8 or the cellulose ester film produced by the production method according to claim 9 has Re (590) = 0 to 200 nm and | Rth ( 590) An optical compensation film obtained by laminating an optically anisotropic layer of | = 0 to 400 nm.   It is a polarizing plate by which a protective film is bonded together on both sides of a polarizing film, Comprising: At least 1 piece of this protective film is a cellulose-ester film in any one of Claims 1-8, The manufacturing method of Claim 9 A polarizing plate, which is a produced cellulose ester film or the optical compensation film according to claim 10.   The cellulose ester film according to claim 1, the cellulose ester film produced by the production method according to claim 9, the optical compensation film according to claim 10, and the polarizing plate according to claim 11. A liquid crystal display device comprising at least one of the above.   The liquid crystal display device according to claim 12, wherein the liquid crystal display device has an IPS mode liquid crystal cell.