JP2010215878A - Cellulose acylate film, polarizing plate, and liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film useful for a liquid crystal display apparatus and having a small longitudinal strain during the wet heat change thereof and having excellent wet heat durability of the retardation thereof in an in-plane direction and/or a film thickness direction. <P>SOLUTION: This cellulose acylate film is a cellulose acylate film in which an acyl group substitution degree DS of a cellulose acylate satisfies the equation (A): 2.0≤DS<2.8 and an absolute value of a change amount of the thickness direction retardation value Rth(590) at a wavelength of 590 nm between before and after the cellulose acylate film is left at rest under conditions of 60°C and 90% of a relative humidity for 24 hours is 5 nm or less, and which is produced by drawing and in which a value AR produced by dividing a dimension change rate of the film in a drawing direction by a dimension change rate of the film in a direction perpendicular to the drawing direction after the drawing is 1.15 to 1.8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical film made of a cellulose acylate film useful for a liquid crystal display device, which has a low expansion / contraction ratio when wet heat changes and is excellent in wet heat durability of in-plane direction and / or film thickness direction retardation. The present invention also relates to a polarizing plate and a liquid crystal display device using the film.

  In general, a liquid crystal display device includes a liquid crystal cell, an optical compensation sheet, and a polarizer. The optical compensation sheet is used for the purpose of eliminating image coloring and expanding the viewing angle, and examples thereof include a stretched birefringent film and a film obtained by applying a liquid crystal to a transparent film. For example, Patent Document 1 discloses a technique for applying an optical compensation sheet in which a discotic liquid crystal is applied on a triacetyl cellulose film, aligned, and fixed to a TN mode liquid crystal cell to widen the viewing angle.

  However, a television-use liquid crystal display device 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. Therefore, 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, have been studied. In particular, the VA mode is becoming mainstream as a liquid crystal display device for TV applications because of its high contrast and relatively high production yield.

  In general, polyvinyl alcohol (hereinafter also referred to as “PVA”) is mainly used as a material of a polarizer essential for a liquid crystal display device. The PVA film is uniaxially stretched and then dyed with iodine or a dichroic dye, or dyed and stretched, and then crosslinked with a boron compound to impart polarization performance and can be used as a polarizer.

  Here, a cellulose acylate film is usually used for applications requiring optical isotropy such as a protective film for a polarizing plate. This is based on the fact that the cellulose acylate film has a characteristic of high optical isotropy (low retardation value) as compared with other polymer films.

  On the other hand, the optical compensation sheet (retardation film) of the liquid crystal display device is required to have optical anisotropy (high retardation value). In particular, an optical compensation sheet for VA requires 30-200 nm front retardation (Re) and 70-400 nm thickness direction retardation (Rth). Therefore, it is common to use a synthetic polymer film having a high retardation value such as a polycarbonate film or a polysulfone film as the optical compensation sheet.

  In other words, the optical member used in the liquid crystal display device uses a synthetic polymer film when the polymer film requires optical anisotropy (high retardation value), and is optically isotropic (low retardation). When the value is required, it was a general principle to use a cellulose acylate film.

  Patent Document 2 proposes a cellulose acetate film having a high retardation value that can be used for applications requiring optical anisotropy, overcoming the conventional general principle. In this proposal, in order to achieve a high retardation value with cellulose triacetate, an aromatic compound having at least two aromatic rings, particularly a compound having a 1,3,5-triazine ring, is added and subjected to stretching treatment. Cellulose triacetate is generally a polymer material that is difficult to stretch, and it is known that it is difficult to increase the birefringence, but it is necessary to increase the birefringence by simultaneously orienting the additives in the stretching process. To achieve a high retardation value. Since this film can also serve as a protective film for the polarizing plate, there is an advantage that an inexpensive and thin liquid crystal display device can be provided by reducing the number of member films necessary for the liquid crystal display device.

  The methods disclosed in Patent Documents 1 and 2 are effective in that an inexpensive and thin liquid crystal display device can be obtained.

  The use of liquid crystal display devices is expanding, and since it is used more often outdoors and installed in passenger cars, durability under humid heat conditions is required. .

  As these improvement methods, Patent Documents 3 and 4 propose a method for increasing the amount of the additive in the cellulose acylate film. However, simply increasing the amount of the additive allows the additive to reach the surface of the cellulose acylate film. In addition to causing deterioration in performance as a polarizing plate and a liquid crystal display device, there was a problem that productivity was lowered due to line contamination in the film forming process, which was not satisfactory.

  On the other hand, there is known a method for improving film properties by adding a styrene-based additive to various resins. For example, an example (Patent Document 5) in which a styrene / maleic anhydride-based additive is added to a cellulose acylate resin and an antioxidant is further added to try to improve the humidity dependency has been disclosed. There is no mention of the durability of the properties.

  Therefore, the dimensional variation is sufficiently small with respect to changes in environmental humidity, and at the same time, it has excellent optical properties that affect display performance, and the manufacturing process is not complicated. At present, the development of technology for obtaining a film, an optical compensation film, a polarizing plate using the film, and a liquid crystal display device is still strongly desired.

Japanese Patent No. 2587398 European Patent Application No. 91656 JP 2002-022956 A JP 2001-354802 A JP 2007-304376 A

  However, as a result of investigation by the present inventors, the cellulose acylate film using only a large amount of a low-molecular plasticizer that is usually used has a slightly smaller change in the wet heat of the film dimensions, but the wet heat durability with sufficient optical characteristics. It was found that the durability in the form of a polarizing plate was inferior.

  Furthermore, problems such as precipitation on the surface of the film during film formation, formation of particles during the saponification treatment, and precipitation after crystallization occurred. That is, these methods are not only insufficient in improving the wet heat durability of the optical properties, but also the cellulose acylate film is formed by solution casting film formation, and the additive precipitates from the web during film formation, so that the device and the film itself are removed. Contamination creates problems that reduce quality and productivity.

  Further, when a method of adding a styrene / maleic anhydride additive to the cellulose acylate resin of Patent Document 5 was examined, when a cellulose acylate resin having a low substitution degree as in the present invention was used, the in-plane direction and It was found that the wet heat durability of retardation in the film thickness direction was not sufficiently improved.

  The inventor has conducted intensive research to overcome the above-described drawbacks. That is, the first object of the present invention is a cellulose acylate film useful for a liquid crystal display device, which has a low expansion / contraction ratio when wet heat changes and is excellent in wet heat durability of in-plane direction and / or film thickness direction retardation. Is to provide. A second object of the present invention is to provide a polarizing plate and a liquid crystal display device using the film.

  As a result of intensive studies, the present inventor has obtained a cellulose acylate film that is excellent in wet heat durability of optical properties and has a sufficiently small shrinkage due to heating and humidification by containing a specific additive and stretching under specific conditions. It was found that when the cellulose acylate film was used as a protective film for a polarizing plate, a polarizing plate excellent in wet heat durability of polarizing plate performance was obtained.

Based on these findings, it has been found that an optical film having a good humidity dependency can be provided and the above-mentioned problems can be solved. Specifically, it has been found that the above problems can be solved by the following means.
[1] Thickness direction retardation at a wavelength of 590 nm before and after standing for 24 hours under the condition of 60 ° C. and 90% relative humidity when the substitution degree of acyl group of cellulose acylate is DS The absolute value of the amount of change of the value Rth (590) is 5 nm or less, the value obtained by stretching, and the dimensional change rate in the stretching direction after stretching is divided by the dimensional change rate in the direction orthogonal to the stretching direction. A cellulose acylate film having an AR of 1.15 to 1.8.
Formula (A): 2.0 ≦ DS <2.8
[2] Front retardation value at a wavelength of 590 nm before and after standing for 24 hours under the conditions of 60 ° C. and 90% relative humidity when the substitution degree of acyl group of cellulose acylate is DS The absolute value of the amount of change in Re (590) is 5 nm or less, a value AR obtained by stretching and dividing the dimensional change rate in the stretching direction after stretching by the dimensional change rate in the direction orthogonal to the stretching direction AR Is a cellulose acylate film characterized by being 1.15 to 1.8.
Formula (A): 2.0 ≦ DS <2.8
[3] The absolute value of the change amount of the front retardation value Re (590) at the wavelength of 590 nm and the absolute value of the change amount of the retardation value Rth (590) in the film thickness direction at the wavelength of 590 nm are both 5 nm. The cellulose acylate film according to [1] or [2], which is the following.
[4] The cellulose acylate film contains 1 to 35 parts by mass of at least one polymer additive, satisfies the following formula (B), and at least one styrenic polymer is added to cellulose acylate film. The cellulose acylate film according to any one of [1] to [3], wherein 3 parts by mass or more is included with respect to 100 parts by mass of the rate film.
Formula (B): | SP value (additive) -SP value (cellulose) | <1.5 MPa ^1/2
(In formula (B), SP value (additive) represents the solubility parameter of the polymer measured by the Hoy method, and SP value (cellulose) represents the solubility parameter of the cellulose acylate measured by the Hoy method.)
[5] The cellulose acylate film according to any one of [1] to [4], wherein the polymer additive has a number average molecular weight of 700 to 10,000.
[6] Both the dimensional change rate S (MD) in the conveyance direction and the dimensional change rate S (TD) in the machine width direction before and after being allowed to stand for 24 hours at 60 ° C. and a relative humidity of 90% are ± 1.0. % Of the cellulose acylate film according to any one of [1] to [5].
[7] The front retardation value Re (590) at a wavelength of 590 nm and the retardation value Rth (590) in the film thickness direction at a wavelength of 590 nm satisfy the following formulas (I) and (II): [1] The cellulose acylate film according to any one of to [6].
Formula (I) 30 nm ≦ Re (590) ≦ 70 nm
Formula (II) 80 nm ≦ Rth (590) ≦ 250 nm
[8] The ratio of Re (590) / Rth (590), which is the ratio between the value of the front retardation Re (590) at a wavelength of 590 nm and the value of the retardation Rth (590) in the film thickness direction at a wavelength of 590 nm, is 0.1. It is -0.8, The cellulose acylate film as described in any one of [1]-[7] characterized by the above-mentioned.
[9] The cellulose acylate film according to any one of [1] to [8], wherein the haze is 1.0% or less.
[10] The cellulose acylate film according to any one of [1] to [9], wherein all of the acyl groups are acetyl groups.
[11] The cellulose reed according to any one of [1] to [10], which contains at least one of a plasticizer, an ultraviolet absorber, a release accelerator, a dye and a matting agent. Rate film.
[12] The cellulose acylate film according to any one of [1] to [11], which contains at least one retardation developer.
[13] A total addition amount of the polymer additive, plasticizer, ultraviolet absorber, release accelerator, dye, matting agent, and retardation enhancer is added in an amount of 4 to 40% by mass with respect to the cellulose acylate resin. The cellulose acylate film according to any one of [1] to [12], wherein:
[14] A polarizing plate, wherein at least one of the cellulose acylate films according to any one of [1] to [13] is used as a protective film for a polarizing plate.
[15] A liquid crystal display device comprising the polarizing plate according to [14].
[16] A liquid crystal display device, wherein the polarizing plate according to [14] is attached to a liquid crystal cell with an adhesive, and the protective film is disposed on the liquid crystal cell side.
[17] The liquid crystal display device according to [15] or [16], wherein the liquid crystal display device is in a VA mode.

  By using the present invention, an optical film made of a cellulose acylate film useful for a liquid crystal display device is obtained which has a low expansion / contraction ratio when wet heat changes and is excellent in wet heat durability of in-plane direction and film thickness direction retardation. be able to.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

[Cellulose acylate film]
<Characteristics of film>
(Change in optical properties)
The stretched cellulose acylate film of the present invention has an absolute change in the thickness direction retardation value Rth (590) at a wavelength of 590 nm before and after standing for 24 hours at 60 ° C. and 90% relative humidity. The value is 5 nm or less.
In another aspect of the present invention, the stretched cellulose acylate film of the present invention has a front retardation value Re (at a wavelength of 590 nm before and after standing for 24 hours at 60 ° C. and 90% relative humidity. 590) has an absolute value of the change amount of 5 nm or less.
The cellulose acylate film of the present invention (hereinafter also referred to as the film of the present invention) more preferably has an absolute value of the change amount of Re and Rth both in the range of 5 nm or less. In order to obtain a film having such a small optical property, it is preferable to adjust the amount, type, and the like of the additive as described later with respect to cellulose acylate. Moreover, in order to satisfy | fill said performance, adding together and using 2 or more types of additives is also used preferably.

  A method for obtaining Re and Rth before and after standing for 24 hours under conditions of 60 ° C. and 90% relative humidity will be described. The produced cellulose acylate film was conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and then was used at 25 ° C. and 60% relative humidity using a birefringence measuring device (KOBRA 21ADH, manufactured by Oji Scientific Instruments). To measure the Re value and the Rth value at a wavelength of 590 nm. Subsequently, the film was allowed to stand for 24 hours at 60 ° C. and a relative humidity of 90%, then conditioned for 2 hours or more at 25 ° C. and a relative humidity of 60%, and at a wavelength of 590 nm at 25 ° C. and a relative humidity of 60%. Re value and Rth value are measured.

  In the present specification, ΔRe and ΔRth are differences obtained by subtracting the Re and Rth values before lapse from the Re and Rth values after lapse of 24 hours under the conditions of 60 ° C. and 90% relative humidity.

  The absolute value of the change amount of Re and the absolute value of the change amount of Rth when the cellulose acylate film of the present invention is allowed to stand for 24 hours at 60 ° C. and 90% relative humidity are preferably within 5 nm. More preferably less than 4 nm, still more preferably less than 2 nm.

(Dimensional change rate)
The cellulose acylate film of the present invention has a small dimensional change rate before and after being allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity. Further, the dimensional change rate S (MD) and the dimensional change rate S (TD) in the conveyance direction (hereinafter also referred to as the machine direction) before and after being left to stand for 24 hours at 60 ° C. and 90% relative humidity. It is more preferable that any of these is in the range of ± 1.0%. In order to obtain a film having such a dimensional change rate, it is preferable to adjust the amount, type, etc. of the additive with respect to the total DS of the cellulose acylate. Moreover, in order to satisfy | fill said performance, adding together and using 2 or more types of additives is also used preferably.

  Here, the conveyance direction dimension change rate S (MD) and the machine width direction dimension change rate S (TD) are the machine conveyance direction (casting direction during casting) and the machine width direction (flow It means the dimensional change rate in the width direction). Specifically, it is obtained by the following method.

A method for obtaining the conveyance direction dimension change rate S (MD) will be described.
A 50 mm x 250 mm sample cut out from the film is conditioned for 2 days or more in an atmosphere of 25 ° C and 60% relative humidity, and then in an automatic pin gauge (made by Shinto Kagaku Co., Ltd.) Holes of 6 mmφ are opened at intervals of 200 mm so as to be parallel, and the original size (L1) of the interval is measured to the minimum scale 1/1000 mm. Then, after thermo-treating at 60 ° C. and 90% relative humidity for 120 hours, or at 80 ° C. and 10% relative humidity for 120 hours, the temperature is adjusted to 25 ° C. and 60% relative humidity for 24 hours, and the punch interval dimension (L2 ). The rate of change in dimension in the conveying direction can be obtained from the following equation.
Dimensional change rate in transport direction S (MD) = {(L2-L1) / L1} × 100

  Further, the dimensional change rate S (TD) in the machine width direction can be obtained by the same method as described above except that a hole by an automatic pin gauge is formed in the machine width direction at the time of film production.

  As the rate of change in dimension S (MD) in the conveyance direction and the rate of change in dimension S (TD) in the machine width direction when the cellulose acylate film of the present invention is allowed to stand for 24 hours under the conditions of 60 ° C. and 90% relative humidity. Any of these is more preferably within ± 0.5%, and further preferably within ± 0.3%.

(Film thickness)
The thickness of the cellulose acylate film of the present invention varies depending on the purpose of use, but is preferably 20 to 200 μm, more preferably 25 to 100 μm, and particularly 30 to 80 μm for liquid crystal display devices. preferable. By setting it as such a range, there exists an effect of the improvement of polarizing plate processability by handling improvement.

(Film width)
The width of the cellulose acylate film of the present invention is preferably 500 to 3000 mm, more preferably 1000 to 2500 mm, and particularly preferably 12000 to 2200 mm for liquid crystal display device applications. By setting it as such a range, there exists an effect of the improvement of the yield by making efficient polarizing plate cutting and handling aptitude compatible.

(Film length)
The length of the cellulose acylate film of the present invention is preferably 100 m to 10000 m per roll, more preferably 500 m to 7000 m, and particularly preferably 1000 m to 6000 m. It is particularly preferably 12000 to 2200 mm for liquid crystal display applications. By setting it as such a range, the handling by a roll form is easy, and also there exists an effect which adapts to the continuous process of a polarizing plate and improves a yield.

(Haze)
The cellulose acylate film of the present invention preferably has a haze of 1% or less, more preferably less than 0.5%, and even more preferably less than 0.3%. By setting the haze to 1% or less, the transparency of the film becomes higher, and there is an advantage that the visibility of the liquid crystal display device is improved by suppressing unnecessary scattering as an optical film.

(Average moisture content)
The cellulose acylate film of the present invention preferably has an equilibrium moisture content of 4% or less at 25 ° C. and a relative humidity of 60%, more preferably 3% or less. By setting the average moisture content to 4% or less, it is easy to cope with a change in humidity, and it is preferable that optical characteristics and dimensions are less likely to change.

(Re, Rth)
The cellulose acylate film of the present invention preferably satisfies the following formula (I) and the following formula (II) at 25 ° C. and 60% relative humidity when used for a retardation film.
Formula (I) 30 nm ≦ Re (590) ≦ 70 nm
Formula (II) 80 nm ≦ Rth (590) ≦ 250 nm
The Re (590 nm) preferably satisfies 30 nm ≦ Re (590) ≦ 70 nm, and particularly preferably satisfies 40 nm ≦ Re (590) ≦ 65 nm.
The Rth (590 nm) more preferably satisfies 80 nm ≦ Rth (590) ≦ 250 nm, and particularly preferably satisfies 90 nm ≦ Rth (590) ≦ 230 nm.

  In the cellulose acylate film of the invention, the ratio Re (590) / Rth (590) between the value of Re (590) and the value of Rth (590) is 0.1 to 0.8. It is preferable when the apparatus is used.

  The variation in the Re value of the entire width of the cellulose acylate film of the present invention is preferably within ± 5 nm, and more preferably within ± 3 nm. Further, the variation in the Rth value is preferably within ± 10 nm, and more preferably within ± 5 nm. Moreover, it is preferable that the variation in the Re value and the Rth value in the length direction is also within the range of the variation in the width direction.

  Here, Re (λ) and Rth (λ) in this specification represent in-plane retardation and retardation in the thickness direction at wavelength λ, respectively. In the present specification, the wavelength λ is 590 nm unless otherwise specified. 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 Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotary axis) (in the absence of the slow axis, any direction in the film plane) Is measured in 6 points from the inclined direction in 10 degree steps from the normal direction to 50 degrees on one side with respect to the normal direction of the film. KOBRA 21ADH calculates based on the retardation value, the assumed average refractive index, and the input film thickness value. The retardation value is measured from any two directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis), and the value Rth can also be calculated from the following formulas (1) and (2) based on the assumed average refractive index and the input film thickness value. 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. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

Here, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. d represents the film thickness.
Rth = ((nx + ny) / 2−nz) × d −−− Formula (2)
At this time, an average refractive index n is required as a parameter, and a value measured by an Abbe refractometer (“Abbe refractometer 2-T” manufactured by Atago Co., Ltd.) was used.

(Cellulose acylate)
The cellulose acylate used in the cellulose acylate film of the present invention is obtained by substituting the hydroxyl group of the glucose unit constituting the cellulose acylate with an acyl group.

  Cellulose acylate raw material cellulose used in the present invention includes cotton linter and wood pulp (hardwood pulp, softwood pulp), etc., and any cellulose acylate obtained from any raw material cellulose can be used, optionally mixed. May be. Detailed descriptions of these raw material celluloses can be found in, for example, Marusawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, published by Nikkan Kogyo Shimbun (published in 1970), and the Japan Society of Invention and Innovation Technical Bulletin No. 2001. The cellulose described in No.-1745 (pages 7 to 8) can be used, and the cellulose ester film of the present invention is not particularly limited.

First, the cellulose ester in which the present invention is preferably used will be described in detail. Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. The cellulose ester is a polymer (polymer) obtained by esterifying some or all of these hydroxyl groups with an acyl group. The degree of acyl substitution means the ratio in which the hydroxyl group of cellulose is esterified at each of the 2-position, 3-position and 6-position (100% esterification has a substitution degree of 1).
Here, the total substitution degree DS of the acyl group is 2.0 ≦ DS <2.8, more preferably 2.1 ≦ DS ≦ 2.7, and still more preferably 2.3 ≦ DS ≦ 2. .6. By setting it as such a range, moisture permeability resistance and optical expression can be made compatible, and the stability of display performance when used in a liquid crystal display device can be further improved. Further, DS6 / (DS2 + DS3 + DS6) is preferably 0.32 or more, more preferably 0.322 or more, and particularly preferably 0.324 to 0.340. Here, DS2 is the degree of substitution of the hydroxyl group at the 2-position of the glucose unit with an acyl group (hereinafter also referred to as “degree of acyl substitution at the 2-position”), and DS3 is the degree of substitution of the hydroxyl group at the 3-position with an acyl group (hereinafter, referred to as “acyl group”). DS6 is the substitution degree of the hydroxyl group at the 6-position with an acyl group (hereinafter also referred to as “acyl substitution degree at the 6-position”). DS6 / (DS2 + DS3 + DS6) is the ratio of the acyl substitution degree at the 6-position to the total acyl substitution degree, and is hereinafter also referred to as “acyl substitution ratio at the 6-position”.

Only one type of acyl group may be used in the cellulose ester of the present invention, or two or more types of acyl groups may be used. The cellulose ester film of the present invention preferably has an acyl group having 2 to 4 carbon atoms as a substituent. When two or more kinds of acyl groups are used, one of them is preferably an acetyl group, and the acyl group having 2 to 4 carbon atoms is preferably a propionyl group or a butyryl group in addition to the acetyl group. DSA is the sum of the substitution degrees of the hydroxyl groups at the 2nd, 3rd and 6th positions by the acetyl group, and DSB is the sum of the substitution degrees of the 2nd, 3rd and 6th hydroxyl groups by the propionyl group or butyryl group. The value is preferably 2.0 ≦ DSA + DSB ≦ 2.8, and more preferably 2.1 ≦ DSA + DSB ≦ 2.7. By setting the DSA and DSB values within the above ranges, a dimensional stability due to environmental humidity can be reduced, and at the same time, a film with reduced wet heat durability of phase difference fluctuation can be obtained.
Further, 28% or more of DSB is a substituent at the 6-position hydroxyl group, more preferably 30% or more is a substituent at the 6-position hydroxyl group, and more preferably 31% or more is a substituent at the 6-position hydroxyl group. In particular, it is also preferred that 32% or more is a substituent of the 6-position hydroxyl group.

  The acyl group of the cellulose of the present invention may be an aliphatic group or an allyl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. Preferred examples of the acyl group of the cellulose of the present invention include acetyl group, propionyl group, butyryl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, Examples include an octadecanoyl group, an isobutanoyl group, a tert-butyryl group, a cyclohexanecarbonyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, and a cinnamoyl group. Among these, an acetyl group, a propionyl group, a butyryl group, a dodecanoyl group, an octadecanoyl group, a tert-butyryl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group, and the like are more preferable, and an acetyl group is particularly preferable. A propionyl group and a butyryl group, and most preferably an acetyl group from the viewpoint that cellulose acylates having various substitution degrees are easily available at a low cost and that the molecular weight is large and the viscosity can be easily controlled during dope preparation. is there.

  In the acylation of cellulose, when an acid anhydride or acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent.

As the catalyst, when the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and when the acylating agent is an acid chloride (for example, CH ₃ CH ₂ COCl), Basic compounds are used.

  The most common industrial synthesis method for mixed fatty acid esters of cellulose is to use cellulose mixed fatty acids containing fatty acids (acetic acid, propionic acid, valeric acid, etc.) corresponding to acetyl groups and other acyl groups or anhydrides thereof. This is a method of acylating with components.

  The cellulose ester used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

(ΔSP value)
In the present invention, the difference between the SP value of the cellulose acylate and the SP value of the additive described later (hereinafter sometimes referred to as “ΔSP value”), that is, | SP value (additive) −SP value (cellulose) | Preferably satisfies the following formula (B).
Formula (B): | SP value (additive) -SP value (cellulose) | <1.5 MPa ^1/2
(In formula (B), SP value (additive) represents the solubility parameter of the polymer measured by the Hoy method, and SP value (cellulose) represents the solubility parameter of the cellulose acylate measured by the Hoy method.)
If ΔSP is less than 1.5, the compatibility between the cellulose acylate and the additive is improved, and whitening and crying are less likely to occur. Moreover, when the dope used for film formation of such a film is formed by a solution casting method, whitening occurs due to moisture in the dope. The value of ΔSP is more preferably 1.3 or less, particularly preferably less than 1.3, and even more preferably less than 1.0. When two or more types of additives are used, it is preferable that the ΔSP value of each additive satisfies the above range.
Moreover, when adding 2 or more types of additives, it is preferable to add between each additive and a cellulose acylate, and also the (DELTA) SP value of additives satisfy | fill the said range. For example, when two kinds of additives are added, the difference between the first additive SP value and the SP value of cellulose acylate, the difference between the second additive SP value and the SP value of cellulose acylate, and one It is preferable that the difference between the SP value of the second additive and the SP value of the second additive satisfies the above range. That is, it is preferable that the difference between the maximum value and the minimum value of the solubility parameter (SP value) of each additive measured by the Hoy method satisfies the following formula (C).
Formula (C): | SP value (maximum value) -SP value (minimum value) | <1.5 MPa ^1/2
Furthermore, the preferable range of the ΔSP value in the formula (C) is the same as the preferable range of the formula (B).
It is preferable to select two or more additives satisfying such a relationship of ΔSP value from the viewpoint of showing excellent compatibility with cellulose acylate. Moreover, it is a point which was not known conventionally that the effect that the haze of a cellulose acylate film can be reduced by using 2 or more types of additives which satisfy | fill the relationship of such (DELTA) SP value is demonstrated.
The SP value in the present invention is a value calculated by the Hoy method, and the Hoy method is described in POLYMER HANDBOOK FOURTH EDITION.

(Additive)
In the present invention, as the additive, known polymer additives and low molecular weight additives can be widely employed as additives for cellulose acylate films. The content of the additive is preferably 1 to 35% by mass, more preferably 4 to 30% by mass, and more preferably 10 to 25% by mass with respect to the cellulosic resin. It is particularly preferred. If the addition amount is 1% by mass or more, it is possible to cope with changes in temperature and humidity, and if the addition amount is 30% by mass or less, the film is hardly whitened and the physical characteristics are also good.
Here, the additive in the present invention is a component added for the purpose of improving various functions of the cellulose acylate film of the present invention, and is contained in a range of 1% by mass or more with respect to the cellulose resin. Ingredients. That is, impurities and residual solvents are not additives in the present invention.
In the present invention, in particular, the content of the polymer additive is preferably 4 to 30% by mass and more preferably 10 to 25% by mass with respect to the cellulose resin.
In the present invention, two or more kinds of additives can be used as long as the value of ΔSP is within a predetermined range. By using two or more types, each additive has the merit that both optical properties, film elastic modulus, film brittleness, and web handling suitability can be achieved.

(Polymer additive)
The polymer additive used in the film of the present invention has a repeating unit in the compound, and the number average molecular weight is preferably 700 to 10,000 from the viewpoint of dope preparation in solution casting. The polymer additive is used in the solution casting method in order to increase the volatilization rate of the solvent or reduce the amount of residual solvent. In addition, the polymer additive is a useful material for preventing coloration and film strength deterioration even in a film formed by the melt film forming method. Furthermore, the addition of the polymer additive to the film of the present invention has a useful effect in terms of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. .

Here, the number average molecular weight of the polymer additive in the present invention is more preferably a number average molecular weight of 700 to 8000, still more preferably a number average molecular weight of 700 to 5000, and particularly preferably a number average molecular weight of 1000 to 5000. is there.
Hereinafter, although the polymer additive used for this invention is demonstrated in detail, giving the specific example, it cannot be overemphasized that the polymer additive used by this invention is not necessarily limited to these.

  The polymer additive is selected from polyester polymers, styrene polymers, acrylic polymers and copolymers thereof, and aliphatic polyesters, aromatic polyesters, acrylic polymers and styrene polymers are preferred. Moreover, it is preferable that at least one polymer having negative intrinsic birefringence, such as a styrene polymer and an acrylic polymer, is included.

Polyester polymer The polyester polymer used in the present invention comprises a mixture of an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and an aromatic dicarboxylic acid having 8 to 20 carbon atoms, an aliphatic diol having 2 to 12 carbon atoms, and a carbon number. Although it is obtained by reaction with at least one diol selected from 4-20 alkyl ether diols and C6-C20 aromatic diols, both ends of the reactants may remain as reactants. Further, the so-called terminal sealing may be carried out by further reacting monocarboxylic acids, monoalcohols or phenols. It is effective in terms of preservability that the end capping is performed in order not to contain free carboxylic acids. The dicarboxylic acid used in the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms preferably used in the present invention include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid. , Sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.
Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8 -Naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

  Among these, preferable aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acid is phthalic acid. Acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid. Particularly preferably, the aliphatic dicarboxylic acid component is succinic acid, glutaric acid, and adipic acid, and the aromatic dicarboxylic acid is phthalic acid, terephthalic acid, and isophthalic acid.

  In the present invention, at least one of each of the above-mentioned aliphatic dicarboxylic acids and aromatic dicarboxylic acids is used in combination, but the combination is not particularly limited, and there is no problem even if several types of each component are combined.

  Examples of the diol or aromatic ring-containing diol used for the polymer additive include, for example, an aliphatic diol having 2 to 20 carbon atoms, an alkyl ether diol having 4 to 20 carbon atoms, and an aromatic ring-containing diol having 6 to 20 carbon atoms. It is chosen from.

  Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols, such as ethane diol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3 -Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more.

  Preferred aliphatic diols include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, particularly preferred Is ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

  Preferred examples of the alkyl ether diol having 4 to 20 carbon atoms include polytetramethylene ether glycol, polyethylene ether glycol and polypropylene ether glycol, and combinations thereof. The average degree of polymerization is not particularly limited, but is preferably 2 to 20, more preferably 2 to 10, further 2 to 5, and particularly preferably 2 to 4. As examples of these, commercially useful polyether glycols typically include Carbowax resin, Pluronics resin and Niax resin.

  Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Bisphenol A, 1,4-hydroxybenzene and 1,4-benzenedimethanol are preferred.

In the present invention, it is particularly preferable that the additive is a polymer additive whose end is sealed with an alkyl group or an aromatic group. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the polyester additive of the present invention are not carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples include substituted alcohols such as propanol.

  End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

Such a polymer additive of the present invention may be synthesized by a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the dicarboxylic acid and a diol and / or a monocarboxylic acid or monoalcohol for end-capping by a conventional method. Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. These polyester-based additives are described in detail in Koichi Murai, “Additives, Theory and Application” (Kokaibo Co., Ltd., first edition published on March 1, 1973). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.
Although the specific example of the polyester-type polymer which can be used by this invention is described below, the polyester-type polymer which can be used by this invention is not limited to these.

  In Tables 1 and 2, PA is phthalic acid, TPA is terephthalic acid, IPA is isophthalic acid, AA is adipic acid, SA is succinic acid, 2,6-NPA is 2,6-naphthalenedicarboxylic acid 2,8-NPA is 2,8-naphthalenedicarboxylic acid, 1,5-NPA is 1,5-naphthalenedicarboxylic acid, 1,4-NPA is 1,4-naphthalenedicarboxylic acid, 1,8 -NPA represents 1,8-naphthalenedicarboxylic acid, respectively. The diol ratios (mol%) are all 100%, and the aliphatic diol average carbon numbers are all 2.0.

Styrenic polymer The styrenic polymer is preferably a structural unit obtained from an aromatic vinyl monomer represented by the general formula (1).

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. R ¹⁰⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ¹⁰⁴ may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.

  Specific examples of the aromatic vinyl monomer include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene. P-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene and other hydroxystyrenes; vinyl benzyl alcohols; p-methoxystyrene, p-tert Alkoxy-substituted styrenes such as butoxystyrene and m-tert-butoxystyrene; vinyl benzoic acids such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; vinyl such as methyl-4-vinylbenzoate and ethyl-4-vinylbenzoate Benzoic acid esters; 4-vinylbenzylacetate 4-acetoxystyrene; amidostyrenes such as 2-butylamidostyrene, 4-methylamidostyrene, p-sulfonamidostyrene; 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, vinylbenzyldimethyl Aminostyrenes such as amines; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, indene The present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component. Of these, styrene and α-methylstyrene are preferred because they are easily available industrially and are inexpensive.

Acrylic polymer The acrylic polymer is preferably a structural unit obtained from an acrylate ester monomer represented by the general formula (1).

In the formula, R ^{105 to} R ¹⁰⁸ each independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. This represents a hydrocarbon group having 1 to 30 or a polar group.

  Examples of the acrylate monomer include, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-). , Pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), acrylic acid Nonyl (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2- Hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid Phosphoric acid (2-ethoxyethyl) phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), acrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), Methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, benzyl methacrylate, phenethyl acrylate, Phenethyl methacrylate, acrylic acid (2-naphthyl), cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), methacrylate Although Le acid (4-ethyl cyclohexyl) or the like, or the acrylic acid ester may include those obtained by changing the methacrylic acid esters, the present invention is not limited to these specific examples. Two or more of these monomers may be used as a copolymerization component. Of these, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, tert-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), or those obtained by replacing the above acrylate esters with methacrylate esters are preferred.

Copolymer The copolymer comprises at least one structural unit obtained from an aromatic vinyl monomer represented by the general formula (1) and an acrylate ester monomer represented by the general formula (2). The inclusion is preferred.

In the formula, each of R ^{101 to} R ¹⁰⁴ independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. R ¹⁰⁴ represents a hydrocarbon group of 1 to 30 or a polar group, and R ¹⁰⁴ may be the same atom or group or different atoms or groups, and may be bonded to each other to form a carbocyclic or heterocyclic ring ( These carbocycles and heterocycles may form a monocyclic structure, or other rings may be condensed to form a polycyclic structure.

In the formula, R ^{105 to} R ¹⁰⁸ each independently represents a substituted or unsubstituted carbon atom which may have a linking group containing a hydrogen atom, a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom. This represents a hydrocarbon group having 1 to 30 or a polar group.

  Further, the structure other than the above constituting the copolymer composition is preferably excellent in copolymerizability with the monomer, and examples thereof include maleic anhydride, citraconic anhydride, cis-1-cyclohexene-1 , 2-dicarboxylic anhydride, 3-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride, 4-methyl-cis-1-cyclohexene-1,2-dicarboxylic anhydride, etc. acid anhydrides, acrylonitrile, Nitrile group-containing radical polymerizable monomers such as methacrylonitrile; Amide bond-containing radical polymerizable monomers such as acrylamide, methacrylamide, trifluoromethanesulfonylaminoethyl (meth) acrylate; Fatty acid vinyls such as vinyl acetate; Chlorine-containing radical polymerizable monomers such as vinyl and vinylidene chloride; 1,3-butadiene; Isoprene, 1,4-dimethyl butadiene and the like can be mentioned conjugated diolefins but the present invention is not limited thereto. Of these, styrene-acrylic acid copolymers, styrene-maleic anhydride copolymers, and styrene-acrylonitrile copolymers are particularly preferred.

  Examples of commercially available styrene polymers include SMA1000 (styrene-maleic anhydride copolymer molar ratio = 50: 50, Tg = 428K), SMA2000 (styrene-maleic anhydride) as styrene-maleic anhydride copolymers. Copolymerization molar ratio = 67: 33, Tg = 408K), SMA3000 (styrene-maleic anhydride copolymerization molar ratio = 75: 25, Tg = 398K), and the like are available from Satomer. Further, as a styrene / acrylic copolymer, JONCRYL682 and the like are available from Johnson Polymer.

The film of the present invention preferably contains 3 parts by mass or more of at least one styrene-based polymer with respect to 100 parts by mass of the cellulose acylate film from the viewpoint of wet heat durability of film optical properties. Furthermore, it is more preferable that 3-10 mass parts is contained with respect to 100 mass parts of cellulose acylate films, and it is especially preferable that 4-8 mass parts is included.
Moreover, it is preferable that the film of this invention contains 10 mass parts or more of at least 1 sort (s) of polyester polymer with respect to 100 mass parts of cellulose acylate films. Furthermore, it is more preferable that 10-40 mass parts is contained with respect to 100 mass parts of cellulose acylate films, and it is especially preferable that 15-30 mass parts is included.
Furthermore, in the film of the present invention, the mass ratio of the addition amount of the styrenic polymer and the addition amount of the polyester polymer is preferably 1: 2 to 1:10, and preferably 1: 3 to 1: 6. More preferred.

(Low molecular weight additive)
Examples of the low molecular weight additive include a retardation reducing agent, a retardation developing agent, a deterioration preventing agent, an ultraviolet ray preventing agent, a peeling accelerator, another plasticizer, and an infrared absorber. These may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, mixing of an ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and a mixture of deterioration preventing agents are also possible. 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 cellulose acylate solution (dope) preparation step, but it may be added by adding a preparation step to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested.

（式中、Ｒ¹はアルキル基またはアリール基を表し、Ｒ²およびＲ³は、それぞれ独立に、水素原子、アルキル基またはアリール基を表す。Ｒ¹、Ｒ²およびＲ³の炭素原子数の総和は１０以上である。）

（式中、Ｒ⁴およびＲ⁵は、それぞれ独立に、アルキル基またはアリール基を表す。Ｒ⁴およびＲ⁵の炭素原子数の総和は１０以上である。） (Retardation reducing agent)
The film of the present invention may contain a retardation reducing agent.
Although it does not specifically limit as a retardation reducing agent, The compound represented by General formula (4)-(7) described below is mentioned. Details are described in JP-A-2007-272177, [0066] to [0074].

(Wherein R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group or an aryl group. The number of carbon atoms of R ¹ , R ² and R ³ is The sum is 10 or more.)

(In the formula, R ⁴ and R ⁵ each independently represents an alkyl group or an aryl group. The total number of carbon atoms of R ⁴ and R ⁵ is 10 or more.)

The compound represented by the general formula (4) or the general formula (5) can be prepared by the following method.
The compound of the general formula (4) can be obtained by a condensation reaction between a sulfonyl chloride derivative and an amine derivative. The compound of the general formula (5) can be obtained by oxidation reaction of sulfide or Friedel-Crafts reaction of aromatic compound and sulfonic acid chloride.

Next, the compound represented by the general formula (6) will be described in detail.

In the general formula (6), R ¹¹ represents an aryl group. R ¹² and R ¹³ each independently represents an alkyl group or an aryl group, and at least one of them is an aryl group. When R ¹² is an aryl group, R ¹³ may be an alkyl group or an aryl group, but more preferably an alkyl 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. The aryl group preferably has 6 to 36 carbon atoms, and more preferably 6 to 24 carbon atoms.

Next, the compound represented by the general formula (7) will be described in detail.

In the general formula (7), R ²¹ , R ²² and R ²³ each independently represents an alkyl group. Here, the alkyl group may be linear, branched or cyclic. R ²¹ is preferably a cyclic alkyl group, and more preferably at least one of R ²² and R ²³ is a cyclic alkyl group. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and most preferably 1 to 12 carbon atoms. As the cyclic alkyl group, a cyclohexyl group is particularly preferable.

  The alkyl group and aryl group in the general formulas (6) and (7) may each have a substituent. Substituents include halogen atoms (for example, chlorine, bromine, fluorine and iodine), alkyl groups, aryl groups, alkoxy groups, aryloxy groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, sulfonylamino groups, A hydroxy group, a cyano group, an amino group and an acylamino group are preferred, more preferably a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a sulfonylamino group and an acylamino group, and particularly preferably an alkyl group and an aryl group. A sulfonylamino group and an acylamino group.

  Next, details of preferable examples of the compounds represented by the general formulas (6) and (7) are described in JP-A-2007-272177, [0075] to [0085].

(Retardation expression agent)
In the present invention, in order to express (enhance) a retardation value, it is preferable to use a retardation developer. Examples of the retardation enhancer that can be used in the present invention include those composed of rod-like or discotic compounds. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer. The addition amount of the retardation enhancer composed of the rod-shaped compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred.
The disk-shaped retardation developer is preferably used in a range of 0.05 to 20 parts by mass, and in a range of 1.0 to 15 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. It is more preferable to use, and it is still more preferable to use in the range of 3.0-10 mass parts.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developer preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, a benzene ring, a condensed benzene ring, and biphenyls are preferable. In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, compounds disclosed in JP-A No. 2001-166144 are preferably used.

The number of carbon atoms of the aromatic ring contained in the retardation enhancer is preferably 2 to 20, more preferably 2 to 12, further preferably 2 to 8, and preferably 2 to 6. Most preferred.
The bond relationship between two aromatic rings can be classified into (a) a condensed ring, (b) a direct bond with a single bond, and (c) a bond through a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of linking groups may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent.
Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (for example, a hydroxy group, a carboxy group, an alkoxy group, an alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- Each group of a diethylaminoethyl group is included.
The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.
The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (for example, an alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer is preferably 300 to 800.

  As the discotic compound, a triazine compound represented by the following general formula (I) is preferably used.

In the above general formula (I):
R ⁵¹ each independently represents an aromatic ring or a heterocyclic ring having a substituent in at least one of the ortho, meta and para positions.
X ¹¹ each independently represents a single bond or —NR ⁵² —. Here, each R ⁵² independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, or a heterocyclic group.

The aromatic ring represented by R ⁵¹ is preferably phenyl or naphthyl, and particularly preferably phenyl. The aromatic ring represented by R ⁵¹ may have at least one substituent at any substitution position. Examples of the substituent include a halogen atom, hydroxyl group, cyano group, nitro group, carboxyl group, alkyl group, alkenyl group, aryl group, alkoxy group, alkenyloxy group, aryloxy group, acyloxy group, alkoxycarbonyl group, Alkenyloxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, alkyl-substituted sulfamoyl group, alkenyl-substituted sulfamoyl group, aryl-substituted sulfamoyl group, sulfonamide group, carbamoyl, alkyl-substituted carbamoyl group, alkenyl-substituted carbamoyl group, aryl-substituted carbamoyl group, amide Groups, alkylthio groups, alkenylthio groups, arylthio groups and acyl groups.

The heterocyclic group represented by R ⁵¹ preferably has aromaticity. The heterocycle having aromaticity is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The heterocyclic ring is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring. The hetero atom of the heterocyclic ring is preferably a nitrogen atom, a sulfur atom or an oxygen atom, and particularly preferably a nitrogen atom. As the heterocyclic ring having aromaticity, a pyridine ring (2-pyridyl or 4-pyridyl as the heterocyclic group) is particularly preferable. The heterocyclic group may have a substituent. Examples of the substituent of the heterocyclic group are the same as the examples of the substituent of the aryl moiety.
When X ¹¹ is a single bond, the heterocyclic group is preferably a heterocyclic group having a free valence on the nitrogen atom. The heterocyclic group having a free valence on the nitrogen atom is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and a 5-membered ring. Is most preferred. The heterocyclic group may have a plurality of nitrogen atoms. Further, the heterocyclic group may have a hetero atom other than the nitrogen atom (for example, O, S). Examples of heterocyclic groups having free valences on nitrogen atoms are shown below. Here, C ₄ H ₉ ⁿ represents normal-C ₄ H ₉ .

The alkyl group represented by R ⁵² may be a cyclic alkyl group or a chain alkyl group, but a chain alkyl group is preferable, and a linear alkyl group is more preferable than a branched chain alkyl group. preferable. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-20, further preferably 1-10, still more preferably 1-8, and 1-6. Most preferred. The alkyl group may have a substituent. Examples of the substituent include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group).

The alkenyl group represented by R ⁵² may be a cyclic alkenyl group or a chain alkenyl group, but is preferably a chain alkenyl group, and is more preferably a linear alkenyl group than a branched chain alkenyl group. More preferably it represents a group. The number of carbon atoms in the alkenyl group is preferably 2 to 30, more preferably 2 to 20, still more preferably 2 to 10, still more preferably 2 to 8, 6 is most preferred. The alkenyl group may have a substituent. Examples of the substituent are the same as those of the alkyl group described above.
The aromatic ring group and heterocyclic group represented by R ⁵² are the same as the aromatic ring and heterocyclic ring represented by R ¹² , and the preferred range is also the same. The aromatic ring group and the heterocyclic group may further have a substituent, and examples of the substituent are the same as those of the aromatic ring and heterocyclic ring of R ⁵¹ .

  As the discotic compound, a triphenylene compound represented by the following general formula (II) can also be preferably used.

In the general formula (II), R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a hydrogen atom or a substituent.
As the substituents represented by R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ , an alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably carbon number). 1-20 alkyl groups, such as methyl, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc. ), An alkenyl group (preferably an alkenyl group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a vinyl group, an allyl group, 2- Butenyl group, 3-pentenyl group and the like), alkynyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 2 carbon atoms). 20 alkynyl groups such as propargyl group and 3-pentynyl group) and aryl groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms). For example, a phenyl group, a p-methylphenyl group, a naphthyl group, and the like, a substituted or unsubstituted amino group (preferably having 0 to 40 carbon atoms, more preferably 0 to 30 carbon atoms, Particularly preferred is an amino group having 0 to 20 carbon atoms, and examples thereof include an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group).

  An alkoxy group (preferably an alkoxy group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group). Aryloxy group (preferably an aryloxy group having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 20 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group. An acyl group (preferably an acyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably 1 to 20 carbon atoms, such as an acetyl group, a benzoyl group, a formyl group, and a pivaloyl group. Etc.), an alkoxycarbonyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably carbon number) To 20 alkoxy groups such as methoxycarbonyl group and ethoxycarbonyl group), aryloxycarbonyl groups (preferably having 7 to 40 carbon atoms, more preferably having 7 to 30 carbon atoms, and particularly preferably carbon atoms). An aryloxycarbonyl group having 7 to 20 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, and particularly preferably 2 carbon atoms). ˜20 acyloxy groups such as an acetoxy group and a benzoyloxy group)

  An acylamino group (preferably an acylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as an acetylamino group and a benzoylamino group), alkoxycarbonyl An amino group (preferably an alkoxycarbonylamino group having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 20 carbon atoms, such as a methoxycarbonylamino group), aryloxy Carbonylamino group (preferably an aryloxycarbonylamino group having 7 to 40 carbon atoms, more preferably 7 to 30 carbon atoms, particularly preferably 7 to 20 carbon atoms, such as a phenyloxycarbonylamino group) Sulfonylamino group (preferably having 1 to 40 carbon atoms, more preferred Or a sulfonylamino group having 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, such as a methanesulfonylamino group and a benzenesulfonylamino group, and a sulfamoyl group (preferably having a carbon number of 0 to 40). More preferably, it is a sulfamoyl group having 0 to 30 carbon atoms, particularly preferably 0 to 20 carbon atoms, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group. ), A carbamoyl group (preferably a carbamoyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, an unsubstituted carbamoyl group, a methylcarbamoyl group, diethylcarbamoyl group Group, phenylcarbamoyl group, etc.),

  Alkylthio group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group , Heptylthio group, octylthio group and the like), arylthio group (preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, for example, phenylthio group). ), A sulfonyl group (preferably a sulfonyl group having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms, and examples thereof include a mesyl group and a tosyl group), sulfinyl Group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 2 carbon atoms) Sulfinyl group, for example, methanesulfinyl group, benzenesulfinyl group, etc.), ureido group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 20 carbon atoms). A ureido group, for example, an unsubstituted ureido group, a methylureido group, a phenylureido group, and the like, a phosphoric acid amide group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, and particularly preferably Is a phosphoric acid amide group having 1 to 20 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group, a hydroxy group, a mercapto group, a halogen atom (for example, a fluorine atom, a chlorine atom, bromine). Atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group A hydrazino group, an imino group, a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, for example, a heterocyclic group having a heteroatom such as a nitrogen atom, oxygen atom, sulfur atom, etc. And examples thereof include imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group, and 1,3,5-triazyl group). Silyl group (preferably a silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group) Is included. These substituents may be further substituted with these substituents. Moreover, when it has two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

The substituent represented by each of R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ is preferably an alkyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group or a halogen atom. is there. Discotic compounds are described in detail in JP-A-7-267902, JP-A-7-281028, and JP-A-7-306317. The discotic compound is preferably a triphenylene derivative.

  The compound represented by general formula (I) is, for example, the method described in JP-A No. 2003-344655, and the compound represented by general formula (II) is, for example, the method described in JP-A-2005-134484. Can be synthesized by a known method.

  In the present invention, rod-like compounds having a linear molecular structure can be preferably used in addition to the above-mentioned discotic compounds. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (for example, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

  As the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (III) is preferable.

Formula (III): Ar ¹ -L ¹ -Ar ²

In the general formula (III), Ar ¹ and Ar ² are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (for example, methyl Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (for example, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-) Dimethylcarbamoyl group), sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido Group, alkylureido group (for example, N-methylureido group, N, N-dimethylureido group, N, N, N′-trimethyl group) Each group of tilureido group), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, heptyl group, octyl group, isopropyl group, s-butyl group, tert-amyl group, cyclohexyl group, cyclopentyl) Group), alkenyl group (for example, vinyl group, allyl group, hexenyl group), alkynyl group (for example, ethynyl group, butynyl group), acyl group (for example, formyl group, acetyl group, butyryl group, Hexanoyl group, lauryl group), acyloxy group (for example, acetoxy group, butyryloxy group, hexanoyloxy group, lauryloxy group), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, butoxy group) Pentyloxy group, heptyloxy group, octyloxy group), arylo Si group (for example, phenoxy group), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group ( For example, phenoxycarbonyl group), alkoxycarbonylamino group (for example, butoxycarbonylamino group, hexyloxycarbonylamino group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group) Each group), arylthio group (for example, phenylthio group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, propylsulfonyl group, butylsulfo group) Group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (for example, acetamido group, butyramide group, hexylamide group, laurylamide group) and non-aromatic heterocyclic group ( For example, a morpholyl group and a pyrazinyl group) are included.

Among these, preferred substituents include halogen atoms, cyano groups, carboxyl groups, hydroxyl groups, amino groups, alkylamino groups, acyl groups, acyloxy groups, amide groups, alkoxycarbonyl groups, alkoxy groups, alkylthio groups, and alkyl groups. Can be mentioned.
The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, Alkylsulfonyl groups, amide groups and non-aromatic heterocyclic groups are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (III), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO—, and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15, more preferably 1 to 10, still more preferably 1 to 8, and most preferably 1 to 6. It is.

The alkenylene group and alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene group or ethynylene group).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (III), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.

As the rod-like compound, a compound represented by the following formula (IV) is more preferable.
Formula ^{(IV): Ar 1 -L 2} -X-L 3 -Ar 2

In the general formula (IV), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those for Ar ¹ and Ar ^{2 in} the general formula (III).

In the general formula (IV), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO—, and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene group). Or ethylene group).
L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

  In the general formula (IV), X is a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.

  Specific examples of the compound represented by the general formula (III) or (IV) include compounds described in [Chemical Formula 1] to [Chemical Formula 11] of JP-A No. 2004-109657.

Two or more rod-shaped compounds having a maximum absorption wavelength (λmax) longer than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized with reference to methods described in the literature. References include Mol. Cryst. Liq. Cryst., 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 Page (1989), J. Am. Chem. Soc., 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org Chem., 40, 420 (1975), Tetrahedron, 48, 16, 3437 (1992).

(Deterioration inhibitor)
In the present invention, a known deterioration (oxidation) inhibitor such as 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3) is added to the cellulose acylate solution. -Methylphenol), 1,1'-bis (4-hydroxyphenyl) cyclohexane, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, pentaerythris Phenolic or hydroquinone antioxidants such as lithyl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] can be added. Further, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, bis (2,6-di-tert) It is preferable to use a phosphorus-based antioxidant such as -butyl-4-methylphenyl) pentaerythritol diphosphite and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The addition amount of the deterioration inhibitor is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the cellulose resin.

(UV absorber)
In the present invention, an ultraviolet absorber is preferably used for the cellulose acylate solution from the viewpoint of preventing deterioration of a polarizing plate or liquid crystal. As the ultraviolet absorber, those excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and having a small absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. Specific examples of ultraviolet absorbers preferably used in the present invention include, for example, hindered phenol compounds, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds Etc. Examples of hindered phenol compounds include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert) -Butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. Examples of benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6 (2H-benzotriazol-2-yl) phenol), (2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5- Triazine, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-tert-butyl-4- Hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, (2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5 -Chlorobenzotriazole, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like. The addition amount of these ultraviolet light inhibitors is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio in the whole cellulose acylate film.

(Peeling accelerator)
The film of the present invention may contain a peeling accelerator. The peeling accelerator can be included at a ratio of 0.001 to 1% by weight, for example. As the peeling accelerator, known ones can be employed, for example, ethyl esters of citric acid.

(Plasticizer)
A plasticizer can be added to the film of the present invention in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass based on the mass of the cellulosic resin.

  The cellulose acylate film of the present invention may contain at least one of a plasticizer, an ultraviolet absorber, a release accelerator, a dye and a matting agent among the low molecular weight additives. From the viewpoint of light resistance and the like.

In the cellulose acylate film of the present invention, among the additives, a total addition amount of a polymer additive, a plasticizer, an ultraviolet absorber, a peeling accelerator, a dye, a matting agent, and a retardation developer is a cellulose acylate resin. 4 to 40% by mass is preferably added to the film from the viewpoints of the elastic modulus and light resistance of the retardation film.
The total addition amount of the polymer additive, the plasticizer, the ultraviolet absorber, the peeling accelerator, the dye, the matting agent, and the retardation developer is more preferably 5 to 30% by mass, and more preferably 10 to 25% by mass. It is particularly preferred.

(Method for producing cellulose ester film)
The film of the present invention can be produced by any method as long as it is a method for normally producing a cellulose acylate film, but is particularly preferably produced by a solvent cast method. In the solvent cast method, a film can be produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent.
The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to contain. The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, —O—, —CO— and —COO—) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.
Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone.
Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate.
Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen in the halogenated hydrocarbon is preferably 25 to 75 mol%, more preferably 30 to 70 mol%, and more preferably 35 to 65 mol%. More preferably, it is most preferable that it is 40-60 mol%. Methylene chloride is a representative halogenated hydrocarbon.
Two or more organic solvents may be mixed and used.

A cellulose acylate solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (room temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a normal solvent cast method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly methylene chloride) as the organic solvent.
The amount of cellulose acylate is adjusted so as to be contained in the obtained solution in an amount of 10 to 40% by mass. The amount of cellulose acylate is more preferably 10 to 30% by mass. Arbitrary additives described later may be added to the organic solvent (main solvent).
The solution can be prepared by stirring the cellulose acylate and the organic solvent at room temperature (0 to 40 ° C.). High concentration solutions may be stirred under pressure and heating conditions. Specifically, cellulose acylate and an organic solvent are placed in a pressure vessel and sealed, and stirred while heating to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be coarsely mixed in advance and then placed in a container. Moreover, you may put into a container sequentially. The container needs to be configured so that it can be stirred. The container can be pressurized by injecting an inert gas such as nitrogen gas. Moreover, you may utilize the raise of the vapor pressure of the solvent by heating. Or after sealing a container, you may add each component under pressure.
When heating, it is preferable to heat from the outside of the container. For example, a jacket type heating device can be used. The entire container can also be heated by providing a plate heater outside the container and piping to circulate the liquid.
It is preferable to provide a stirring blade inside the container and stir using this. The stirring blade preferably has a length that reaches the vicinity of the wall of the container. A scraping blade is preferably provided at the end of the stirring blade in order to renew the liquid film on the vessel wall.
Instruments such as a pressure gauge and a thermometer may be installed in the container. Each component is dissolved in a solvent in a container. The prepared dope is taken out of the container after cooling, or taken out and then cooled using a heat exchanger or the like.

(Film forming process)
From the prepared cellulose acylate solution (dope), a cellulose acylate film can be produced by a solvent cast method.
The dope is cast on a drum or band, and the solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 18 to 35% by mass. The surface of the drum or band is preferably finished in a mirror state. As for casting and drying methods in the solvent casting method, U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-1115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried by high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

  A method of drying a web which has been dried on a drum or belt and peeled off will be described. The web peeled at the peeling position just before the drum or belt makes one round is conveyed by alternately passing through a group of rolls arranged in a staggered manner, or the both ends of the peeled web are gripped by clips or the like and are not contacted. It is conveyed by the method of conveying it automatically. Drying is performed by a method of applying wind at a predetermined temperature to both sides of the web (film) being conveyed or a method using a heating means such as a microwave. Since rapid drying may impair the flatness of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds. In the drying process after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film. From this point, for example, as shown in Japanese Patent Laid-Open No. 62-46625, a method in which all or part of the drying process is performed while holding the width at both ends of the web with clips or pins in the width direction. (Tenter method) is preferred. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. Although the drying temperature, the amount of drying air, and the drying time differ depending on the solvent used, it may be appropriately selected according to the type and combination of the solvents used. In the method for producing a cellulose ester film of the present invention, the web (film) peeled from the support is preferably stretched when the residual solvent amount in the web is less than 120% by mass, particularly in the range of 10 to 100% by mass. In the meantime, it is preferably performed at 5 to 300% in at least one direction, more preferably 7 to 200%, and further preferably 10 to 100%.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at an arbitrary point in time, and N is the mass when the web of which M is measured is dried at 110 ° C. for 3 hours. If the amount of residual solvent in the web is too large, the effect of stretching cannot be obtained, and if it is too small, stretching becomes extremely difficult and the web may break. The more preferable range of the residual solvent amount in the web is 10% by mass to 70% by mass, and most preferably 12% by mass to 50% by mass. Further, if the stretching ratio is too small, a sufficient phase difference cannot be obtained, and if it is too large, stretching may become difficult and breakage may occur. Since the cellulose acylate film of the present invention has a large expression of optical anisotropy due to stretching, the stretching ratio is preferably 5 to 100%, more preferably 7 to 70%, and more preferably 10 to 50% from a practical viewpoint. Is particularly preferred. A film formed by solution casting can be stretched without being heated to a high temperature if the amount of residual solvent is in a specific range, but drying and stretching are preferable because the process can be shortened. However, since the plasticizer volatilizes when the temperature of the web is too high, a range of room temperature (for example, 15 ° C) to 145 ° C or less is preferable.

  Further, in the present invention, the obtained cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. You may cast. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Further, a film may be formed by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-6-247245 It can be carried out by the methods described in JP-A-61-104813, JP-A-61-158413, and JP-A-6-134933. Further, a cellulose acylate in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high-viscosity and low-viscosity cellulose acylate solutions are simultaneously extruded. A film casting method may be used. Furthermore, it is also a preferable embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution.

  Alternatively, by using two casting ports, peeling the film formed on the metal support by the first casting port, and performing the second casting on the side that was in contact with the metal support surface, A film may be produced, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Further, the cellulose acylate solution of the present invention may be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer). .

  In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a required film thickness. In many cases, a problem occurred due to the occurrence of an object, a fault, or poor flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also a concentrated cellulose acylate solution can be used to reduce the drying load and increase the film production speed.

  In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, and more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness.

  In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as a plasticizer, an ultraviolet absorber, and a matting agent. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. It is also possible to change the type of plasticizer and UV absorber between the core layer and the skin layer. For example, the skin layer contains a low-volatile plasticizer and / or UV absorber, and the core layer has excellent plasticity. It is also possible to add a plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect that a release agent is contained only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

The cellulose acylate film of the present invention can be efficiently produced by using the production method described in detail below.
The method for producing a cellulose acylate film of the present invention comprises a film-forming step of casting a solution obtained by dissolving a cellulose ester in an organic solvent on a support and evaporating the solvent to form a film, and then stretching the film. It is a manufacturing method of a film which has a drying process which dries the film obtained after that, and the film obtained after that, and has the process of heat-treating for 1 minute or more at the temperature of 150-200 ° C after the end of this drying process, To do.

(Stretching process)
When the cellulose acylate film of the present invention is stretched, it is preferably performed in a state where the solvent still remains in the film immediately after peeling. The purpose of general stretching is (1) to obtain a film having excellent flatness without wrinkles and deformation and uniform retardation in the in-plane direction and / or (2) to increase the in-plane retardation of the film. To do.

  In the stretching in the production method of the present invention, the preferred residual volatile content concentration in the raw dry film at the start of stretching is 15 to 60% by mass, more preferably 20 to 50% by mass, and particularly preferably 25 to 40% by mass. . From a practical viewpoint, the stretching ratio is preferably 10 to 100%, more preferably 12 to 60%, and particularly preferably 15 to 45%. The amount of residual solvent is preferably 15% by mass or more in terms of giving uniform stretching in the in-plane direction of the film. On the other hand, the amount of residual solvent is preferably 60% by mass or less in that the strength and elasticity of the film are large, unintentional cutting and elongation are unlikely to occur, and the distribution of retardation in the in-plane direction is unlikely to vary. Furthermore, there is an advantage that the self-holding force is sufficient, deformation, wrinkles, and nicks are hardly generated, and it is useful as an optical film.

  The stretching of the film may be uniaxial stretching only in the longitudinal or transverse direction with respect to the film conveying direction, or simultaneous or sequential biaxial stretching, but simultaneous or sequential biaxial stretching is preferable in terms of optical property development and uniform control. The birefringence of the retardation film for a VA liquid crystal cell or OCB liquid crystal cell is preferably such that the refractive index in the width direction is larger than the refractive index in the length direction. Therefore, it is preferable to stretch more in the width direction (lateral direction).

The cellulose acylate film of the present invention has a value obtained by dividing the dimensional change rate in the stretching direction after stretching by the dimensional change rate in the direction orthogonal to the stretching direction, that is, the deformation ratio in the stretching direction / the deformation ratio in the orthogonal direction (hereinafter referred to as the deformation ratio). , Also referred to as AR) is 1.15 to 1.8. Stretching so as to satisfy such a specific magnification is preferable from the viewpoint of obtaining a film having desired optical characteristics and the physical characteristics of the obtained film.
Here, the AR can be obtained by the following method.
First, the dimensional change rate in the stretching direction specifically refers to a value obtained by dividing the length in the stretching direction of the film after stretching by the length in the stretching direction of the film before stretching.
More specifically, the dimensional change rate in the direction orthogonal to the stretching direction is obtained by dividing the length in the direction orthogonal to the stretching direction of the film after stretching by the length in the direction orthogonal to the stretching direction of the film before stretching. Value.
AR is the ratio of the dimensional change rates in these two directions, and can be obtained by the following equation (D).
Formula (D):
Dimensional change ratio in the stretching direction Deformation ratio in the stretching direction / Deformation ratio in the orthogonal direction (AR) = --------------------------- -------
Dimensional change rate in a direction orthogonal to the stretching direction The AR is more preferably 1.2 to 1.8, and particularly preferably 1.2 to 1.5.
If the AR is 1.15 or more, the required optical characteristics can be reached. If the AR is 1.8 or less, the film is difficult to cut, the film is not easily turbid (craze) due to minute breakage, and changes in wet heat. The time expansion / contraction rate can be reduced.

  In stretching in the production method of the present invention, it is preferable to relax the film after stretching and to shrink the stretched film.

  In the relaxation step, for example, it is preferable that the stretched film is contracted by holding the horizontally stretched cellulose acylate film at a predetermined temperature for a predetermined time. The relaxation rate is preferably within 20%, more preferably within 15%, and particularly preferably within 10%. If the relaxation rate is too high, the film being transported is loosened, so that the running property is deteriorated and handling is not only worsened, but also the optical characteristic variation is increased due to the variation of the transport tension. If the holding temperature is too low, the molecular orientation in the stretching process is frozen and it becomes difficult to make the retardation value uniform, so that it is preferably held at 100 ° C. or higher, more preferably 120 ° C. or higher. The holding time is preferably 10 to 300 seconds, more preferably 30 to 180 seconds. If the holding time is too short, the stress relaxation effect is small and the retardation value cannot be made uniform, and if it is too long, the variation of the retardation value in the film thickness direction increases.

(Drying process)
The cellulose acylate film is preferably further dried and wound after stretching. When winding, it is preferable to impart a knurling to at least one end, the width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

  As the winder for winding the obtained film, a commonly used winder can be used, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with a constant internal stress. It can be wound up by a take-up method. In the cellulose acylate film roll obtained as described above, the slow axis direction of the film is preferably ± 2 degrees with respect to the winding direction (longitudinal direction of the film), and more preferably ± 1 degree. A range is preferable. Alternatively, it is preferably ± 2 degrees with respect to the direction perpendicular to the winding direction (film width direction), and more preferably within a range of ± 1 degree. In particular, the slow axis direction of the film is preferably within ± 0.1 degrees with respect to the winding direction (longitudinal direction of the film). Alternatively, it is preferably within ± 0.1 degrees with respect to the width direction of the film.

  The film obtained as described above is preferably 1% by mass or less, more preferably 0.2% by mass or less in terms of the residual solvent amount of the final finished film.

[Polarizer]
In the embodiment of the polarizing plate of the present invention, at least one of the cellulose acylate films of the present invention is used as a protective film for the polarizing plate. That is, the polarizing plate is composed of a polarizer and two transparent protective films arranged on at least one side, usually both sides thereof. In the present invention, the cellulose acylate film of the present invention is used as at least one protective film. The other protective film may be a cellulose acylate film according to the present invention or a normal cellulose acetate film.

As described above, the polarizing plate is formed by laminating and laminating a protective film for polarizing plate on at least one surface of the polarizer. A conventionally known polarizer can be used. For example, a hydrophilic polymer film such as a polyvinyl alcohol film is treated with a dichroic dye such as iodine and stretched. The bonding of the cellulose ester film and the polarizer is not particularly limited,
It can be performed with an adhesive comprising an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.
Moreover, you may have a phase difference film | membrane further on the protective film of a polarizing plate. The retardation film is preferably bonded with an adhesive. As an adhesive, the thing as described in each specification of Unexamined-Japanese-Patent No. 2000-109771, Unexamined-Japanese-Patent No. 2003-34781, and Unexamined-Japanese-Patent No. 2003-34781 is employable, for example.

  As a configuration of the polarizing plate of the present invention, a protective film / polarizer / protective film / liquid crystal cell / cellulose acylate film / polarizer / polarizing plate protective film of the present invention, or polarizing plate protective film / polarizer / book The cellulose acylate film of the invention / liquid crystal cell / cellulose acylate film / polarizer / polarizing plate protective film of the invention can be preferably used. In particular, by bonding to a liquid crystal cell such as a TN type, a VA type, or an OCB type, it is possible to provide a display device that is further excellent in viewing angle and visibility with little coloring. In particular, a polarizing plate using the cellulose acylate film of the present invention has little deterioration under high temperature and high humidity conditions, and can maintain stable performance for a long time.

[Liquid Crystal Display]
The cellulose acylate film of the present invention and the polarizing plate using the film can be used for liquid crystal cells and liquid crystal display devices in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal, AFLC) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

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

In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of tech. Papers (Preliminary Proceed) 28 (1997) 845 in which the VA mode is made into a multi-domain (MVA mode) for widening the viewing angle ), (3) a liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Sharp Technical Report No. 80, page 11); (4) The liquid crystal cell of SURVAVAL mode (Monthly Display May 14th page (1999)) is included.
The VA mode liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates. In one aspect of the transmission type liquid crystal display device of the present invention, the film of the present invention is disposed between the liquid crystal cell and one polarizing plate, or between the liquid crystal cell and both polarizing plates. Arrange two.

  In another aspect of the transmissive liquid crystal display device of the present invention, an optical compensation sheet made of the film of the present invention is used as a transparent protective film for a polarizing plate disposed between a liquid crystal cell and a polarizer. The above optical compensation sheet may be used only for the protective film (between the liquid crystal cell and the polarizer) of one polarizing plate, or two (between the liquid crystal cell and the polarizer) of both polarizing plates. You may use said optical compensation sheet for a sheet of protective film. When the optical compensation sheet is used for only one polarizing plate, it is particularly preferable to use it as a protective film for the liquid crystal cell side of the backlight side polarizing plate of the liquid crystal cell. When the film of the present invention is used as a protective film for the polarizing plate of the present invention, the polarizing plate is adhered to the liquid crystal cell with an adhesive, and the protective film is bonded to the liquid crystal cell (VA). It is preferable to be arranged on the (cell) side. The protective film may be a normal cellulose ester film, and is preferably thinner than the film of the present invention. For example, 40-80 micrometers is preferable, and commercially available KC4UX2M (40 μm manufactured by Konica Capto Corporation), KC5UX (60 μm manufactured by Konica Captor Corporation), TD80 (80 μm manufactured by Fuji Film Co., Ltd.) and the like can be mentioned.

  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.

[Production Example 1]
(Preparation of cellulose acylate)
Cellulose acylates having different types of acyl groups and different degrees of substitution described in Table 1 were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. In addition, aging was performed at 40 ° C. after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In addition, in the cotton type in the table, CAB is an abbreviation for cellulose acetate butyrate (cellulose ester derivative in which an acyl group is an acetyl group and a butyryl group), and CAP is cellulose acetate propionate (acyl group). Is an abbreviation for a cellulose ester derivative comprising an acetyl group and a propionyl group), and CA means cellulose acetate (a cellulose ester derivative having an acyl group composed solely of an acetyl group). In addition, the degree of substitution A in the table indicates the degree of substitution derived from the acetyl group, and the degree of substitution B indicates the degree of substitution of the substituent described in the “type” column in the table. Here, Pr represents a propionyl group, and Bu represents a butyryl group.

[Evaluation methods]
(Solubility parameter (SP value))
All the solubility parameters (SP values) in the present invention were values calculated by the Hoy method.

[Film formation of cellulose acylate film]
[Examples 1 to 13, Comparative Examples 1 to 13]
(Dissolution)
As the cellulose acylate and additive described in Table 3, polymer additive 1 and polymer additive 2 described in Table 3, and retardation developer 1 (RP1) or retardation developer 2 described in Table 4 (RP2) was added to dichloromethane / methanol (87/13 parts by mass) with stirring, and the mixture was stirred and dissolved to prepare a dope. The dopes were prepared so that the viscosity was in the range of 50 to 70 Pa · s. At this time, the matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd., secondary average particle size of 1.0 μm or less) 0.13 parts by mass is simultaneously formed with respect to 100 parts by mass of cellulose acylate. The dispersion was mixed and stirred. The addition amount of each additive of Table 4 is a mass part of the additive with respect to 100 mass parts of cellulose acylate.

上記表３中、ＳＭＡ ３０００Ｐ、ＳＭＡ ２０００ＰおよびＳＭＡ１０００Ｐはサートマー社製であり、ＪＯＮＣＲＹＬ６８２はＢＡＳＦ社製のものである。また、それぞれスチレン系ポリマーである。

In Table 3 above, SMA 3000P, SMA 2000P, and SMA1000P are manufactured by Sartomer, and JONCRYL682 is manufactured by BASF. Each is a styrenic polymer.

(Casting and stretching)
The above-mentioned dope was cast using a band casting machine. The film peeled off from the band in the range of 25 to 40% by mass of the residual solvent was stretched in the width direction using a tenter at a stretching temperature of 150 ° C. A rate film was formed. The draw ratio here indicates the maximum draw ratio in the tenter. The maximum draw ratio was based on the casting width. Table 4 shows values obtained by dividing the dimensional change rate in the drawing direction after drawing by the dimensional change rate in the direction orthogonal to the drawing direction, and the deformation ratio (AR) in the drawing direction / orthogonal direction. Table 5 shows the width and film thickness of the obtained film.

(Re, Rth)
The cellulose acylate film thus prepared was conditioned at 25 ° C. and 60% relative humidity for 2 hours or more, and was measured at 25 ° C. and 60% relative humidity using a birefringence measuring apparatus (KOBRA 21ADH, manufactured by Oji Scientific Instruments). And Re and Rth values at a wavelength of 590 nm were measured. The obtained values are shown in Table 5.

(ΔRe, ΔRth)
Further, the film was allowed to stand for 24 hours at 60 ° C. and a relative humidity of 90%, then conditioned for 2 hours or more at 25 ° C. and a relative humidity of 60%, and Re at a wavelength of 590 nm at 25 ° C. and a relative humidity of 60%. Values and Rth values were measured. Table 5 shows the Re value and Rth value before thermo, and the difference between the Re value and Rth value before and after thermo, as ΔRe and ΔRth.
A The absolute value of ΔRe or ΔRth was 0 nm or more and less than 2 nm.
○ The absolute value of ΔRe or ΔRth was 2 nm or more and less than 4 nm.
The absolute value of ΔΔRe or ΔRth was 4 to 5 nm.
X The absolute value of ΔRe or ΔRth exceeded 5 nm.
For those that could not be quantitatively evaluated due to whitening of the film, this is shown in Table 5.

(Haze)
The produced cellulose acylate film was conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and the haze was measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments).
The results of the haze test are shown in Table 5 with the following ranking.
A haze value was 0% or more and less than 0.3%.
○ The haze value was 0.3% or more and less than 0.5%.
Δ The haze value was 0.5 to 1.0%.
X The haze value exceeded 1.0%.
For those that could not be quantitatively evaluated due to whitening of the film, this is shown in Table 5.

(Dimensional change rate)
The dimensional change rate S (MD) in the conveyance direction and the dimensional change rate S (TD) in the machine width direction when the produced cellulose acylate film was allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity were measured. . The definition and measuring method of the dimensional change rate S (MD) in the casting direction and the dimensional change rate S (TD) in the casting width direction are as described above.
The results of the dimensional change rate are shown in Table 5 with the following ranking.
The absolute value of the dimensional change rate was 0% or more and less than 0.3%.
○ The absolute value of the dimensional change rate was 0.3% or more and less than 0.5%.
Δ: The absolute value of the dimensional change rate was 0.5 to 1.0%.
X The absolute value of the dimensional change rate exceeded 1.0%.
For those that could not be quantitatively evaluated due to whitening of the film, this is shown in Table 5.

  From Table 5, according to this result, the film according to the present invention has a small absolute value of ΔRe or ΔRth of 5 nm or less, a haze value of 1.0% or less, and a small dimensional change in a moist heat environment. I found out that

Furthermore, all the samples of the present invention had a photoelastic coefficient of 50 × 10 ⁻¹³ cm ² / dyne or less, and satisfied a sufficient performance as an optical film.

[Examples 101 to 105, Comparative examples 101 to 102]
(Preparation of polarizing plate)
A polyvinyl alcohol (PVA) film having a thickness of 75 μm and a polymerization degree of 2400 was swollen with warm water at 30 ° C. for 40 seconds, and then immersed in an aqueous solution having an iodine concentration of 0.06% by mass and potassium iodide of 6% by mass at 30 ° C. for 60 seconds. Then, while immersed in an aqueous solution having a boric acid concentration of 4% by mass and potassium iodide of 3% by mass at 40 ° C. for 60 seconds, the longitudinal direction becomes 5.0 times the original length. Stretched. Then, it was made to dry at 50 degreeC for 4 minute (s), and the polarizer was obtained.

The film produced in each Example and Comparative Example was added at 1.5 mol / liter in an aqueous sodium hydroxide solution at 30 ° C., and TD80U manufactured by Fuji Film Co., Ltd. was added at 1.5 mol / liter at 55 ° C. sodium hydroxide. After being immersed in the aqueous solution, the sodium hydroxide was sufficiently washed away with water. Then, after dipping for 15 seconds in a dilute sulfuric acid aqueous solution at 0.05 mol / liter at 35 ° C., the dilute sulfuric acid aqueous solution was sufficiently washed away by dipping in water. Finally, the sample was thoroughly dried at 120 ° C. The raw film used is shown in Table 6 below.
The film subjected to the saponification treatment as described above and TD80U manufactured by Fuji Film Co., Ltd. were bonded using a polyvinyl alcohol adhesive so as to sandwich the polarizer, and further heated at 70 ° C. for 30 minutes. Thereafter, the sheet was cut with a cutter 3 cm from the width direction to produce a roll-shaped polarizing plate having an effective width of 1200 mm and a length of 50 m. At this time, since the polarizer and the protective films on both sides of the polarizer are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Moreover, in the protective film arrange | positioned at the cell side, the transmission axis of a polarizer and the slow axis of each cellulose acylate film are parallel.

(Preparation of acrylic polymer solution)
n-butyl acrylate (n-BA) 75 parts by mass, methyl acrylate (MA) 20 parts by mass, 2-hydroxy acrylate (2-HEA) 5 parts by mass, ethyl acetate 100 parts by mass and azobisisobutyronitrile (AIBN) After 0.2 part by mass was put into a reaction vessel and the air in the reaction vessel was replaced with nitrogen gas, the reaction vessel was heated to 60 ° C. in a nitrogen atmosphere with stirring and reacted for 4 hours. After 4 hours, 100 parts by mass of toluene, 5 parts by mass of α-methylstyrene dimer and 2 parts by mass of AIBN were added, the temperature was raised to 90 ° C., and the mixture was further reacted for 4 hours. After the reaction, it was diluted with ethyl acetate to obtain an acrylic polymer solution having a solid content of 20% by mass. To 100 parts by mass of the solid content of the polymer solution, 1.0 part by mass of an isocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred well to obtain an adhesive composition.

(Preparation of polarizing plate with adhesive)
An adhesive was applied to the polarizing plate produced above.
A 25 μm pressure-sensitive adhesive layer is formed on a film obtained by removing the pressure-sensitive adhesive composition containing the acrylic polymer solution, and transferred to a polarizing plate (on the cell-side protective film). The temperature is 23 ° C. and the humidity is 65%. It was made to age | cure | ripen on conditions for 7 days, and the polarizing plate with an adhesive of Examples 101-105 and Comparative Examples 101-102 was produced. Further, a separate film was pasted on the adhesive layer. A protective film was affixed on the protective film opposite to the cell.

(Polarizing plate durability)
Shimadzu before and after preparing two sets of the polarizing plates with pressure-sensitive adhesives of Examples 101 to 105 and Comparative Examples 101 to 102 prepared above and affixed to a glass plate for 1000 hours at 60 ° C. and 90% RH Parallel transmittance and orthogonal transmittance were measured with a UV3100 spectrophotometer, and the degree of polarization was calculated. Durability was evaluated according to the following criteria.

A Polarization degree change amount was 0% or less and exceeded -0.3%.
○ Polarization degree change amount was -0.3% or less and exceeded -0.5%.
Δ: The amount of change in polarization degree was -0.5% or less and exceeded -1.0%.
× The degree of polarization change was -1.0% or less.
The results are shown in Table 6. In the polarizing plate using the film according to the present invention, it is apparent that the change in the degree of polarization with respect to heat and humidity is small and the durability is excellent.

  Further, the polarizing plate of the present invention produced in Example 5 has a dimensional change rate S (MD) in the conveyance direction and a dimensional change rate in the machine width direction when left for 24 hours at 60 ° C. and 90% relative humidity. When S (TD) was measured, the absolute values of the dimensional change rates S (MD) and S (TD) both showed good results of 1.0% or less.

(Mounting on VA panel)
The front and back polarizing plates and retardation plates of a VA mode liquid crystal TV (LC-20C5, manufactured by Sharp Corporation) were peeled off, and the front and back sides were prepared and conditioned in Examples 101-105 and Comparative Examples 101-102. A commercially available polarizing plate (HLC2-5618, manufactured by Sanlitz Co., Ltd.) without a polarizing plate viewing angle compensation plate was attached using a laminator roll. The combination of bonding was such that both the backlight-side polarizing plate and the viewing-side polarizing plate were the same two polarizing plates in each example and comparative example.
In this case, the absorption axis of the polarizing plate on the viewing side is in the horizontal direction of the panel, the absorption axis of the polarizing plate on the backlight side is in the vertical direction of the panel, and the pressure-sensitive adhesive surface is on the liquid crystal cell side.
The obtained liquid crystal display device was made into the liquid crystal display device of Examples 101-105 and Comparative Examples 101-102.

(Viewing angle durability)
Using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle (range with a contrast ratio of 10 or more and no black-side gradation inversion) in 8 stages from black display (L1) to white display (L8) ) Was measured. The liquid crystal display device using the polarizing plate of the present invention and the comparative example showed a good viewing angle of 80 degrees or more on both the left and right sides at 25 ° C. and a relative humidity of 60%. Thereafter, the liquid crystal display device is allowed to stand for 24 hours under conditions of 60 ° C. and 90% relative humidity, and then conditioned for 2 hours or more at 25 ° C. and 60% relative humidity, and again at 25 ° C. and 60% relative humidity. When the angle was measured, the right viewing angle of 80 degrees or more on both the left and right sides was rated as “◯”, and the other cases were marked as “X”.

  From the results in Table 6, it was found that the polarizing plate using the film of the example of the present invention was a polarizing plate having a small change in the degree of polarization with respect to heat and humidity, excellent durability, and excellent display performance. In addition, it was found that the liquid crystal display device using the film of the embodiment of the present invention was excellent in viewing angle durability.

According to the present invention, it has become possible to provide a cellulose acylate film that has sufficiently small dimensional variation with respect to changes in humidity in the use environment and that has excellent wet heat durability with optical characteristics. That is, the cellulose acylate film of the present invention can be preferably used as a protective film for a polarizing plate and an optical compensation film.
Moreover, the polarizing plate of the present invention is excellent in wet heat durability. Therefore, the present invention can provide a liquid crystal display device in which variations in color shift, color, and light leakage are sufficiently small with respect to changes in humidity in the usage environment.

Claims (17)

When the substitution degree of acyl group of cellulose acylate is DS, the following formula (A) is satisfied, and the film thickness direction retardation value Rth (wavelength direction 590 nm) before and after standing for 24 hours at 60 ° C. and 90% relative humidity. 590) is an absolute value of 5 nm or less, and the value AR obtained by dividing the dimensional change rate in the stretching direction after stretching by the dimensional change rate in the direction orthogonal to the stretching direction is 1 A cellulose acylate film having a thickness of 15 to 1.8.
Formula (A): 2.0 ≦ DS <2.8 When the substitution degree of acyl group of cellulose acylate is DS, the following retardation (A) is satisfied, and the front retardation value Re (590) at a wavelength of 590 nm before and after standing for 24 hours at 60 ° C. and 90% relative humidity. The absolute value of the change amount is 5 nm or less, the value AR obtained by dividing the dimensional change rate in the drawing direction after drawing by the dimensional change rate in the direction orthogonal to the drawing direction is 1.15. A cellulose acylate film characterized by being -1.8.
Formula (A): 2.0 ≦ DS <2.8   The absolute value of the change amount of the front retardation value Re (590) at the wavelength of 590 nm and the absolute value of the change amount of the retardation value Rth (590) in the film thickness direction at the wavelength of 590 nm are both 5 nm or less. The cellulose acylate film according to claim 1 or 2. The cellulose acylate film 100 contains 1 to 35 parts by mass of at least one polymer additive with respect to 100 parts by mass of the cellulose acylate film, satisfies the following formula (B), and contains at least one styrenic polymer. It contains 3 mass parts or more with respect to a mass part, The cellulose acylate film as described in any one of Claims 1-3 characterized by the above-mentioned.
Formula (B): | SP value (additive) -SP value (cellulose) | <1.5 MPa ^1/2
(In formula (B), SP value (additive) represents the solubility parameter of the polymer measured by the Hoy method, and SP value (cellulose) represents the solubility parameter of the cellulose acylate measured by the Hoy method.)   The number average molecular weight of the said polymer additive is 700-10000, The cellulose acylate film as described in any one of Claims 1-4 characterized by the above-mentioned.   Both the dimensional change rate S (MD) in the transport direction and the dimensional change rate S (TD) in the machine width direction before and after being left for 24 hours at 60 ° C. and 90% relative humidity are in the range of ± 1.0%. The cellulose acylate film according to any one of claims 1 to 5, wherein The front retardation value Re (590) at a wavelength of 590 nm and the retardation value Rth (590) in the film thickness direction at a wavelength of 590 nm satisfy the following formulas (I) and (II): The cellulose acylate film according to any one of the above.
Formula (I) 30 nm ≦ Re (590) ≦ 70 nm
Formula (II) 80 nm ≦ Rth (590) ≦ 250 nm   The Re (590) / Rth (590) ratio, which is the ratio between the value of the front retardation Re (590) at a wavelength of 590 nm and the value of the retardation Rth (590) in the film thickness direction at a wavelength of 590 nm, is 0.1-0. The cellulose acylate film according to claim 1, wherein the cellulose acylate film is 8.   The cellulose acylate film according to claim 1, wherein the haze is 1.0% or less.   All the said acyl groups are acetyl groups, The cellulose acylate film as described in any one of Claims 1-9 characterized by the above-mentioned.   The cellulose acylate film according to any one of claims 1 to 10, comprising at least one of a plasticizer, an ultraviolet absorber, a peeling accelerator, a dye and a matting agent.   The cellulose acylate film according to claim 1, comprising at least one retardation developing agent.   The total addition amount of the polymer additive, plasticizer, ultraviolet absorber, release accelerator, dye, matting agent, and retardation enhancer is 4 to 40% by mass with respect to the cellulose acylate resin. The cellulose acylate film according to claim 1, wherein the cellulose acylate film is a film.   A polarizing plate, wherein at least one of the cellulose acylate films according to claim 1 is used as a protective film for a polarizing plate.   A liquid crystal display device comprising the polarizing plate according to claim 14.   The polarizing plate of Claim 14 is stuck to the liquid crystal cell with the adhesive, The said protective film is arrange | positioned at the liquid crystal cell side, The liquid crystal display device characterized by the above-mentioned.   The liquid crystal display device according to claim 15, wherein the liquid crystal display device is in a VA mode.