JP2013076749A - Cellulose acylate film and method for manufacturing the same, polarizing plate, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose acylate film which is a thin film, has high optical expression properties per unit film thickness, has a low internal haze, and has little dimensional changes in a hot and wet environment.SOLUTION: A method for manufacturing the cellulose acylate film includes the steps of: forming a polymer solution containing cellulose acylate having the total substitution degree of 1.5 to 2.7, a solvent and an additive into a film shape; and stretching the film so as to have a film thickness of 20 to 65 μm. The stretching step satisfies the following conditions: (1) the quantity A of a residual solvent at the beginning of stretching is 35 to 65 mass%; and (2) the ambient temperature T of the film during stretching is Tg(°C)-70(°C) to Tg(°C)-30(°C).

Description

  The present invention relates to a cellulose acylate film, a method for producing the same, a polarizing plate, and a liquid crystal display device.

  Polymer films represented by cellulose acylate, polyester, polycarbonate, cycloolefin polymer, vinyl polymer, polyimide, and the like are used for silver halide photographic light-sensitive materials, retardation films, polarizing plates, and image display devices. . From these polymers, films that are more excellent in terms of flatness and uniformity can be produced, and are therefore widely used as films for optical applications. For example, a cellulose acylate film having an appropriate moisture permeability can be directly bonded on-line with a most common polyvinyl alcohol (PVA) / iodine polarizer. For this reason, cellulose acylate, particularly cellulose acetate, has been widely adopted as a protective film for polarizing plates.

  When the cellulose acylate film is used for an optical application such as a retardation film, a support for the retardation film, a protective film for a polarizing plate, and a liquid crystal display device, the control of the optical anisotropy is performed in the liquid crystal display device. This is a very important factor in determining performance. In a liquid crystal display device, it is a well-known technique to use an optical compensation film for widening the viewing angle, improving image coloring, and improving contrast. In the most widespread VA (Vertically Aligned) mode (vertical alignment mode), TN (Twisted Nematic) mode, etc., a retardation film capable of controlling optical characteristics (for example, Re value and Rth value) to a desired value is required. Yes. In addition, there is still a need for further improvement in the display performance of liquid crystal display devices and reduction in manufacturing cost, and even when the film thickness is thin, the viewing angle can be sufficiently compensated, and an inexpensive phase difference that can further increase the contrast. There is a need for films. In particular, in recent years, demand for slate PCs and the like has increased, and a thinner and lighter display has been required, and a thinner retardation film has also been required. Furthermore, it is required to reduce the dimensional change rate of the optical compensation film in a humid heat environment, and to reduce light leakage during black display of the liquid crystal display device caused by the film being distorted by humidity or heat ( For example, see Patent Document 1).

  On the other hand, in Patent Document 1, a cellulose acylate having a low total acyl substitution degree is used to stretch a cellulose acylate film to which a high molecular weight additive is added under a specific temperature condition, and further, a wet heat treatment under a specific condition. Thus, there is described a method for producing a cellulose acylate film having a high optical expression and a low dimensional change rate in a wet heat environment. In patent document 1, it extended | stretched on said specific temperature conditions by extending | stretching the residual solvent amount at the time of an extending | stretching start as 0% or 40%.

  Further, in Patent Document 2, an optical film having high retardation expression and small influence by humidity fluctuation is obtained by stretching a cellulose acylate film to which an additive having a specific structure is added. It is described. In Patent Document 2, stretching was performed with the residual solvent amount at the start of stretching being 15%.

  Furthermore, in Patent Document 3, in addition to the acrylic polymer having negative intrinsic birefringence for the heterogeneous cotton mixed cellulose acylate modified with a phthalyl group and an acetyl group, a sugar ester compound is used in combination. It describes that light leakage, uneven color, front contrast, retardation and the like can be improved. In Patent Document 3, it is described that it is preferable to carry out at a relatively high temperature under the condition that the residual solvent in the film of the stretching initiator is small, and the residual solvent amount in the film of the stretching initiator is 20 to 0%. Was described as preferred.

JP 2010-250298 A JP 2011-2633 A JP 2009-1696 A

When this inventor examined the film manufactured by the method of permissible literature 1, it turned out that a film thickness is thick and dissatisfaction remains in the retardation expression per film thickness.
Moreover, when the film manufactured by the method of patent document 2 was examined, it turned out that internal haze is high and dissatisfaction remains in front contrast when it incorporates in a liquid crystal display device.
Furthermore, when the film described in Patent Document 3 was examined, it was found that various performances did not reach the level required in recent years and the internal haze was large.

  An object of the present invention is to provide a cellulose acylate film that satisfies all of the above requirements. That is, the problem to be solved by the present invention is to provide a cellulose acylate film that is a thin film, has a high optical expression per film thickness, a low internal haze, and a small dimensional change in a moist heat environment. It is in.

  In order to solve the above problems, the present inventor examined stretching conditions using cellulose acylate having a low total acyl substitution degree, and controls the amount of residual solvent at the start of stretching and the stretching temperature during stretching. As a result, it has been found that a cellulose acylate film which is a thin film, has a high optical expression per film thickness, a small internal haze, and a small dimensional change in a moist heat environment can be obtained. As a result of intensive studies, the present inventor has found that the above problem is solved by the following configuration.

[1] A step of forming a polymer solution containing cellulose acylate having a total substitution degree of 1.5 to 2.7, a solvent and an additive into a film, and a film thickness after stretching the film is 20 to 65 μm The method for producing a cellulose acylate film is characterized in that the step of stretching includes the following conditions (1) and (2).
(1) The residual solvent amount A at the start of stretching is 35% by mass to 65% by mass.
(2) The film atmosphere temperature T during stretching is Tg (° C.)-70 (° C.) to Tg (° C.)-30 (° C.).
(However, Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film dried in an unstretched state)
[2] In the method for producing a cellulose acylate film according to [1], the stretching step includes stretching in a direction orthogonal to the film transport direction, and a stretch ratio in the direction orthogonal to the film transport direction is 15%. It is preferably ˜60%.
[3] The method for producing a cellulose acylate film according to [2] further includes stretching in the film transport direction simultaneously with stretching in the direction perpendicular to the film transport direction or before and after stretching in the orthogonal direction. Is preferred.
[4] The method for producing a cellulose acylate film according to any one of [1] to [3] preferably includes a polycondensation ester or a sugar ester as the additive in the polymer solution.
[5] In the method for producing a cellulose acylate film according to any one of [1] to [4], the content of the additive in the polymer solution is 5% by mass with respect to the cellulose acylate. It is preferably ˜25% by mass.
[6] In the method for producing a cellulose acylate film according to any one of [1] to [5], the cellulose acylate film after the stretching step satisfies the following formulas (1) to (5). It is preferable to adjust the residual solvent amount A at the start of stretching, the stretching ratio, and the film atmosphere temperature T during stretching.
Formula (1) 20 μm ≦ d ≦ 65 μm
Formula (2) 0.0008 ≦ Re (550) [nm] / d [nm] ≦ 0.003
Formula (3) 0.002 ≦ Rth (550) [nm] / d [nm] ≦ 0.0065
Formula (4) 0% ≦ IH ≦ 0.07%
Formula (5) −0.2% ≦ LMD, LTD ≦ 0.2%
(In the formulas (1) to (5), d is the film thickness, Re (550) is the in-plane retardation at 550 nm, Rth (550) is the retardation in the film thickness direction at 550 nm, and IH is the noise inside. LMD and LTD represent the rate of change in film dimension in the longitudinal direction and the width direction after being subjected to a wet heat treatment for 1 day at 60 ° C. and a relative humidity of 90%, respectively.
[7] The method for producing a cellulose acylate film according to any one of [1] to [6] is a step of forming the polymer solution into a film, wherein the polymer for a band layer includes cellulose acylate and a solvent. And a polymer solution for a core layer containing cellulose acylate having a total acyl group substitution degree of 1.5 to 2.7, a solvent and an additive as the polymer solution on the support in this order simultaneously or sequentially. It is preferable to perform multilayer casting so that the dry film thickness of the core layer polymer solution is larger than the dry film thickness of the band layer polymer solution.
[8] In the method for producing a cellulose acylate film according to [7], it is preferable that the polymer solution for a band layer contains a peeling accelerator.
[9] In the method for producing a cellulose acylate film according to [7], it is preferable that the total substitution degree of the cellulose acylate in the polymer solution for a band layer exceeds 2.7.
[10] A cellulose acylate film produced by the method for producing a cellulose acylate film according to any one of [1] to [9].
[11] A polarizing plate comprising a polarizer and at least one cellulose acylate film according to [10].
[12] A liquid crystal display device comprising a liquid crystal cell and at least one cellulose acylate film according to [10] or at least one polarizing plate according to [11].
[13] The liquid crystal display device according to [12], wherein the liquid crystal cell is a VA mode liquid crystal cell.

  According to the present invention, it is possible to provide a cellulose acylate film that is a thin film, has a high optical expression per film thickness, has a small internal haze, and has a small dimensional change in a moist heat environment. Further, by using the cellulose acylate film of the present invention, it is possible to provide a liquid crystal display device exhibiting good display performance and a polarizing plate used in the liquid crystal display device.

It is sectional drawing for demonstrating an example of the manufacturing method of the cellulose acylate film of this invention.

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

[Method for producing cellulose acylate film]
The method for producing a cellulose acylate film of the present invention (hereinafter, also referred to as the production method of the present invention) is obtained by forming a polymer solution containing cellulose acylate having a total substitution degree of 1.5 to 2.7, a solvent and an additive into a film form. And the step of stretching the film so that the film thickness after stretching is 20 to 65 μm, and the stretching step satisfies the following conditions (1) and (2): To do.
(1) The residual solvent amount A at the start of stretching is 35% by mass to 65% by mass.
(2) The film atmosphere temperature T during stretching is Tg (° C.)-70 (° C.) to Tg (° C.)-30 (° C.).
(However, Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film dried in an unstretched state)
Although not bound by any theory, in the production method of the present invention, by such a configuration, the cellulose acylate is stretched with a large amount of residual solvent and deformed without leaving any strain in a state where the molecular mobility of cellulose acylate is high. Therefore, it is considered that the dimensional change can be reduced in a humid heat environment. In addition, it is considered that the reduction in film thickness due to the drying process promotes the orientation of cellulose acylate in the film thickness direction, thereby increasing the retardation in the film thickness direction and reducing the final film thickness of the film. . Furthermore, by reducing the cast film thickness, even if the amount of residual solvent is large at the start of the stretching process, it can be appropriately dried by controlling to a specific temperature during stretching, and as a result, the film It is considered that a film having a high optical expression per thickness, a small internal haze, and a small dimensional change in a moist heat environment was obtained.
Hereinafter, the manufacturing method of the cellulose acylate film of this invention is demonstrated.

<Film forming process>
In the method for producing a cellulose acylate film of the present invention, the film is preferably formed by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. In the method for producing a cellulose acylate film of the present invention, a film is formed using a polymer solution containing cellulose acylate having a total substitution degree of 1.5 to 2.7, a solvent and an additive.
First, materials that can be added to the polymer solution will be described.

[Cellulose acylate]
The cellulose acylate film of the present invention contains cellulose acylate having a total substitution degree of 1.5 to 2.7.
Examples of the film material contained in the cellulose acylate film of the present invention include cellulose esters, and ester substitution obtained by introducing a functional group biologically or chemically from the cellulose acylate and other cellulose as raw materials. Examples thereof include compounds having a cellulose skeleton. In addition, it is preferable that the cellulose acylate film of this invention contains the said cellulose acylate as a main component. Here, “as the main component” indicates a polymer when it is composed of a single polymer, and when it is composed of a plurality of polymers, the polymer having the highest mass fraction among the constituent polymers. It shows that.

  The cellulose acylate is an ester of cellulose and carboxylic acid, and the carboxylic acid is more preferably a fatty acid having 2 to 22 carbon atoms, and cellulose acylate being a lower fatty acid having 2 to 4 carbon atoms. Most preferred.

(Cellulose acylate raw material)
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. May be. Detailed descriptions of these raw material celluloses are, for example, “Plastic Materials Course (17) Fibrous Resin” (Marusawa, Uda, Nikkan Kogyo Shimbun, 1970) 7 to 8) can be used, and the cellulose acylate film of the present invention is not particularly limited.

(Degree of substitution of cellulose acylate)
Next, the cellulose acylate suitable for the present invention produced from the above-mentioned cellulose will be described.

  The cellulose acylate used in the present invention is one in which the hydroxyl group of cellulose is acylated, and the substituent can be any acetyl group having 2 carbon atoms to 22 carbon atoms. In the present invention, there is no particular limitation on the measurement of the degree of substitution of cellulose with a hydroxyl group in cellulose acylate, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured and calculated. The degree of substitution can be obtained. As a measuring method, it can carry out according to ASTM D-817-91.

In the cellulose acylate used in the production method of the present invention, the total acyl substitution degree of the cellulose acylate is 1.5 to 2.7, and the total acyl substitution degree is 2.1 to 2.70. Is more preferable, 2.1 to 2.60 is more preferable, and 2.2 to 2.5 is particularly preferable.
If the total acyl substitution degree of the cellulose acylate used in the production method of the present invention is in the above preferred range, it is more preferable in terms of optical properties and humidity stability of the optical properties, and if it is 2.60 or less, lower haze is obtained. It is preferable from the viewpoint that can be realized.

When the cellulose acylate used in the production method of the present invention produces a laminated film by casting a polymer solution on a support in multiple layers, the dry film thickness of the polymer solution for the core layer is the same as that of the polymer solution for the band layer. By making the film thickness thicker than the dry film thickness, if the cellulose acylate satisfying the above-mentioned range of the total acyl substitution degree of the present invention is used for the core layer polymer solution, the effects of the present invention can be sufficiently obtained. The preferred range of the total acyl substitution degree of the cellulose acylate used in the polymer solution for the core layer is the same as the above-mentioned range of the present invention.
In this case, the total acyl substitution degree of the cellulose acylate used for the polymer solution for the band layer is not particularly limited, and a cellulose acylate having a total acyl substitution degree of 1.5 to 2.7 may be used. A cellulose acylate having a degree of substitution exceeding 2.7 may be used.
When the total acyl substitution degree of the cellulose acylate used for the band layer polymer solution is 1.5 to 2.7, it is preferable that the band layer polymer solution further contains a peeling accelerator. The preferred range of the total acyl substitution degree of the cellulose acylate used in the band layer polymer solution at this time is the same as the preferred range of the total acyl substitution degree of the cellulose acylate used in the core layer polymer solution.
On the other hand, an embodiment using cellulose acylate having a total acyl substitution degree exceeding 2.7 of the cellulose acylate used in the polymer solution for the band layer is also preferable, and a peeling accelerator is added by such a different cotton multilayer casting. Even if not, the peelability from the support can be improved. The preferable range of the total acyl substitution degree of the cellulose acylate used for the band layer polymer solution at this time is 2.8 to 3.0, more preferably 2.80 to 2.90.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an aryl group, and is not particularly limited. A mixture of They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, or aromatic alkyl carbonyl esters of cellulose, each of which may further have a substituted group. These preferred acyl groups include acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group I-butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred. Further preferred groups are an acetyl group and propionyl, and the most preferred group is an acetyl group.

On the other hand, as said C3-C22 acyl group, a propionyl group and a butyryl group are preferable, and a propionyl group is more preferable.
When the cellulose acylate has both a propionyl group as a substituent, the acetyl group and the propionyl group preferably have a value of X + Y when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y. Is the same as the preferred range of the total acyl substitution degree of the cellulose acylate. The value of Y is preferably 0 to 1.0, more preferably 0.2 to 1.0, and particularly preferably 0.5 to 1.0.

  The degree of polymerization of the cellulose acylate preferably used in the present invention is preferably 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, and 180 to 350. Is particularly preferred. If the degree of polymerization is not more than the upper limit, the viscosity of the cellulose acylate dope solution does not become too high, and a film can be easily produced by casting. If the degree of polymerization is equal to or greater than the lower limit, it is preferable because there is no inconvenience such as a decrease in strength of the produced film. The viscosity average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method {Kazuo Uda, Hideo Saito, "Journal of the Textile Society", Vol. This method is also described in detail in JP-A-9-95538.

  The molecular weight distribution of cellulose acylate preferably used in the present invention is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is small, and the molecular weight A narrow distribution is preferred. The specific value of Mw / Mn is preferably 1.0 to 4.0, more preferably 2.0 to 4.0, and most preferably 2.3 to 3.4. preferable.

〔Additive〕
In the production method of the present invention, known additives can be widely employed as additives for cellulose acylate films. In the production method of the present invention, the content of the additive is preferably 1 to 35% by mass, more preferably 4 to 30% by mass, and 5 to 25% by mass with respect to the cellulose acylate. It is particularly preferable that the content is 10 to 15% by mass. If the amount of the additive added to the cellulose acylate is 1% by mass or more, it is possible to cope with changes in temperature and humidity, and if it is 30% by mass or less, the film is hardly whitened, and physical properties are also preferable.
Here, the additive in the present invention is a component added for the purpose of improving various functions of the optical film of the present invention, and is included in a range of 1% by mass or more with respect to cellulose acylate. Say. That is, impurities and residual solvents are not additives in the present invention.
In the present invention, two or more kinds of additives can be used. 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.

  In the production method of the present invention, the additive is added to the polymer solution from the viewpoint of obtaining a cellulose acylate film having a high optical expression per film thickness, a small internal haze, and a small dimensional change in a wet heat environment. As a polycondensation ester or a sugar ester. Moreover, it is preferable to add the optical expression agent of the specific structure mentioned later from a viewpoint of improving the optical expression per film thickness. Further, when a laminated film is produced by multilayer casting in the production method of the present invention, especially when the total acyl substitution degree of the cellulose acylate used for the support-side band layer dope is low, the support-side band layer dope It is preferable from the viewpoint of improving peelability to add a peel accelerator.

(Polycondensed ester)
The production method of the present invention preferably contains a polycondensed ester as the additive in the polymer solution.
In addition, both ends of the polycondensation ester used in the present invention are independently —OH group, —O—C (═O) —R ¹ group, —C (═O) —O—R ² group, —O. It is preferably any one selected from the group consisting of —R ³ group and —COOH group (wherein R ^{1 to} R ³ each independently represents an aliphatic group).

  In the present specification, the residue of the polycondensed ester is a partial structure of the polycondensed ester and represents a partial structure having the characteristics of the monomer forming the polycondensed ester. For example, the dicarboxylic acid residue formed from the dicarboxylic acid HOOC-R—COOH is —OC—R—CO—, and the diol residue formed from the diol HO—R′—OH is —O—R′—O—. It is.

In the polycondensed ester, an aromatic dicarboxylic acid residue and an aliphatic dicarboxylic acid residue can be used as the dicarboxylic acid residue.
The polycondensation ester used in the present invention preferably contains at least one aromatic dicarboxylic acid residue.
Moreover, it is preferable that the ratio of the aromatic dicarboxylic acid residue with respect to all the dicarboxylic acid residues in the polycondensation ester used for this invention is 50 mol% or more.
By setting the aromatic dicarboxylic acid residue ratio to 50 mol% or more, a cellulose acylate film that exhibits sufficient optical expression even when the film thickness is thin (particularly, the value of Rth per film thickness is large) is obtained. It tends to be.

In the present specification, the aromatic dicarboxylic acid residue refers to a dicarboxylic acid residue containing at least one arylene group. That is, in the present specification, the aromatic dicarboxylic acid residue includes, for example, -OC-Ar'-L-CO- and -OC-L'- in addition to -OC-Ar-CO- residue. Dicarboxylic acid residues having a structure such as Ar ″ —CO— or —OC—L ″ —Ar ′ ″ — L ″ —CO— (Ar, Ar ′, Ar ″ and Ar ′ ″ described above) Each independently represents an arylene group, and L, L ′ and L ″ each independently represents a divalent linking group other than an arylene group). Examples of the divalent linking group other than the arylene group include an aliphatic group and an atom linking group, and specific examples include an alkylene group, an alkyleneoxy group, an oxygen atom, and a sulfur atom. it can.
Among these, the aromatic dicarboxylic acid residue preferably has a structure of —OC—Ar—CO— residue from the viewpoint of compatibility with cellulose acylate.

  Ar is preferably an arylene group having 6 to 16 carbon atoms, more preferably an arylene group having 6 to 12 carbon atoms, particularly preferably a phenylene group or a naphthylene group, and a phenylene group. Is more particularly preferred. The Ar may or may not further have a substituent, but preferably does not have a substituent. Examples of the substituent include a hydroxyl group, an acyl group, and a carbonyl group. Examples include groups.

Specific examples of the aromatic dicarboxylic acid residue include phthalic acid residue, terephthalic acid residue, isophthalic acid residue, 1,5-naphthalenedicarboxylic acid residue, 1,4-naphthalenedicarboxylic acid residue, 1, Examples thereof include an 8-naphthalenedicarboxylic acid residue, a 2,8-naphthalenedicarboxylic acid residue, and a 2,6-naphthalenedicarboxylic acid residue. Among these examples, phthalic acid residues, terephthalic acid residues, and 2,6-naphthalenedicarboxylic acid residues are preferable, phthalic acid residues and terephthalic acid residues are more preferable, and terephthalic acid residues are more preferable.
In the polycondensed ester, an aromatic dicarboxylic acid residue is formed by the aromatic dicarboxylic acid used for mixing.
When the polycondensed ester contains a terephthalic acid residue as an aromatic dicarboxylic acid residue, it is more compatible with cellulose acylate and causes bleed-out during film formation and heat stretching of the cellulose acylate film. It can be set as a difficult cellulose acylate film.

  Further, the polycondensed ester may contain only one kind of aromatic dicarboxylic acid residue or two or more kinds thereof. When two types of aromatic dicarboxylic acid residues are included in the polycondensed ester, it is preferable that a phthalic acid residue and a terephthalic acid residue are included.

The polycondensed ester may contain an aliphatic dicarboxylic acid residue as the dicarboxylic acid residue in addition to the aromatic dicarboxylic acid residue.
Specific examples of the aliphatic dicarboxylic acid residue include, for example, oxalic acid residue, malonic acid residue, succinic acid residue, maleic acid residue, fumaric acid residue, glutaric acid residue, adipic acid residue, Examples thereof include a pimelic acid residue, a suberic acid residue, an azelaic acid residue, a sebacic acid residue, a dodecanedicarboxylic acid residue, or a 1,4-cyclohexanedicarboxylic acid residue.
In the polycondensed ester, an aliphatic dicarboxylic acid residue is formed from the aliphatic dicarboxylic acid used for mixing.
The aliphatic dicarboxylic acid residue preferably has an average carbon number of 5.5 to 10.0, more preferably 5.5 to 8.0, and 5.5 to 7.0. Is more preferable. If the average carbon number of the aliphatic diol is 7.0 or less, the heat loss of the compound can be reduced, and the occurrence of planar failure that may be caused by process contamination due to bleed-out when the cellulose acylate web is dried can be prevented. . Moreover, it is preferable that the aliphatic diol has an average carbon number of 2.5 or more because the compatibility is excellent and precipitation of the polycondensed ester hardly occurs.
Specifically, when the polymerizable ester includes the aliphatic dicarboxylic acid residue, the polymerizable ester preferably includes a succinic acid residue or an adipic acid residue, and more preferably includes a succinic acid residue.
The polycondensed ester may contain only one type of aliphatic dicarboxylic acid residue or two or more types. When two types of aliphatic dicarboxylic acid residues are contained in the polycondensed ester, it is preferable that a succinic acid residue and an adipic acid residue are contained. When one kind of aliphatic dicarboxylic acid residue is contained in the polycondensed ester, it is preferable that a succinic acid residue is contained. By setting it as such an aspect, the average carbon number of a diol residue can be adjusted to the said preferable range, and compatibility with a cellulose acylate becomes favorable.

In the polycondensed ester, an aromatic diol residue and an aliphatic diol residue can be used as the diol residue.
The polycondensed ester used in the present invention contains at least one aliphatic diol residue as a diol residue.

  Examples of the aliphatic diol used in the present invention include alkyl diols and alicyclic diols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 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, diethylene glycol, cyclohexanedimethanol, etc. Is preferably used together with ethylene glycol as one or a mixture of two or more.

Among them, in the present invention, the ratio of the aliphatic diol residue having 3 or more carbon atoms to all diol residues (hereinafter also referred to as the ratio of aliphatic diol having 3 or more carbon atoms) is 30 mol. % Or more of the polycondensation ester is preferable from the viewpoint of improving the compatibility between the cellulose acylate and the polycondensation ester and improving the solubility of the polycondensation ester in the solvent.
The ratio of the aliphatic diol having 3 or more carbon atoms is more preferably 30 mol% or more, and particularly preferably 50 to 80 mol%.

Examples of the aliphatic diol residue having 3 or more carbon atoms include 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1,3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) residue, Examples include 1,4-hexanediol residue, 1,4-cyclohexanediol residue and the like. Among them, the aliphatic diol residue having 3 or more carbon atoms preferably used in the present invention includes 1,2-propanediol residue, 1,3-propanediol residue, 1,2-butanediol residue, 1, 3-butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol) residue, more preferably 1,2-propanediol residue, 1,3-propanediol residue residue, 1,2-butanediol, 1,3-butanediol residue. Group, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, particularly preferably 1,2-propanediol residue.
By using a 1,2-propanediol residue or a 1,3-propanediol residue, crystallization of the polycondensed ester can be prevented.

When an aliphatic diol residue is used as a diol residue other than the aliphatic diol having 3 or more carbon atoms, an ethylene glycol residue or the like can be used.
In the polycondensed ester, an aliphatic diol residue is formed by the aliphatic diol used for mixing.

The polycondensed ester may contain an aromatic diol residue as the diol residue in addition to the aliphatic diol residue.
Specific examples of the aromatic diol residue include, for example, bisphenol A residue, 1,2-hydroxybenzene residue, 1,3-hydroxybenzene residue, 1,4-hydroxybenzene residue, 1,4- Examples thereof include benzenedimethanol residues.

The polycondensed ester may contain only one type of aliphatic diol residue or two or more types. When two types of aliphatic diol residues are included in the polycondensed ester, it is preferable that 1,2-propanediol residues and ethylene glycol residues are included.
In the polycondensed ester, an aromatic diol acid residue is formed from the aromatic diol used for mixing.

Even if the terminal of the polycondensed ester is not sealed and remains a —OH group derived from a diol or a —COOH group derived from a dicarboxylic acid, it reacts with a monocarboxylic acid or a monoalcohol to cause so-called terminal sealing. -O—C (═O) —R ¹ group, —C (═O) —O—R ² group and —O—R ³ group (provided that R ^{1 to} R ³ are each independently Represents an aliphatic group).

  When both ends of the polycondensed ester are unsealed, it is preferable from the viewpoint of inhibiting hydrolysis of the ester group that both ends are —OH groups than both ends are —COOH. That is, when both ends of the polycondensed ester are unsealed, the polycondensed ester is preferably a polyester polyol.

When both ends of the polycondensed ester are sealed, both ends are —O—C (═O) —R ¹ group, —C (═O) —O—R ² group or —O—R ³ group. It is preferable that More preferably, both ends are —O—C (═O) —R ¹ groups, that is, both ends of the polycondensed ester are more preferably sealed by reacting with an aliphatic monocarboxylic acid. .
At this time, both ends of the polycondensed ester are aliphatic monocarboxylic acid residues.

Here, said R < ¹ > -R < ³ > represents an aliphatic group each independently. The aliphatic group represented by R ^{1 to} R ³ may be saturated or unsaturated as long as the aliphatic group does not contain an aromatic ring. The aliphatic group represented by R ^{1 to} R ³ may be either a chain aliphatic group or a cyclic aliphatic group (for example, a cycloalkyl group), and a chain aliphatic group. If it is, it may be linear or branched. The aliphatic group represented by R ^{1 to} R ³ may further have a substituent unless it is contrary to the spirit of the present invention, and the substituent is not particularly limited as long as it does not contain an aromatic ring. An aliphatic group having no substituent is preferred. Moreover, it is preferable that carbon number of the aliphatic group which said R < ¹ > -R < ³ > represents is 1-21, It is more preferable that it is 1-5, It is especially preferable that it is 1-3, 1 or 2 More preferably, it is more preferably 1.
Among them, the aliphatic group represented by R ^{1 to} R ³ is preferably a chain saturated aliphatic group, more preferably a chain alkyl group, and particularly preferably a linear alkyl group. .

That is, when both ends of the polycondensed ester are sealed, both ends of the polycondensed ester are preferably acyl groups having 2 to 22 carbon atoms, and are acyl groups having 2 to 6 carbon atoms. More preferably, it is particularly preferably an acyl group having 2 to 4 carbon atoms (that is, an acetyl group, a propionyl group or a butyryl group), and an acyl group having 2 or 3 carbon atoms (that is, an acetyl group or a propionyl group) More preferably, it is more preferably an acyl group having 2 carbon atoms (that is, an acetyl group). The acyl group here includes an aromatic acyl group (a so-called aroyl group) in addition to an aliphatic acyl group, and is preferably an aliphatic acyl group. When the carbon number of the acyl group at both ends of the polycondensed ester is 3 or less, the volatility is lowered, the weight loss due to heating of the polycondensed ester is not increased, and the occurrence of process contamination and surface failure is reduced. Is possible.
In this case, the monocarboxylic acid used for sealing is preferably an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 6 carbon atoms, and 2 carbon atoms. It is particularly preferably an aliphatic monocarboxylic acid having 4 to 4, more preferably an aliphatic monocarboxylic acid having 2 or 3 carbon atoms, and more preferably an aliphatic monocarboxylic acid residue having 2 carbon atoms. Even more preferable.

On the other hand, when both ends of the polycondensed ester are sealed, both ends of the polycondensed ester may be a —C (═O) —O—R ² group or a —O—R ³ group.
In this case, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and the like are preferable as monoalcohols used for sealing, and methanol is most preferable.

Both ends of the polycondensed ester are each independently an —OH group or —O—C (═O) —R ¹ group (provided that a plurality of R ¹ are present from the viewpoint of controlling compatibility with cellulose acylate). In some cases, each independently represents an aliphatic group). The both ends may be the same group or different groups, but both are preferably the same group from the viewpoint of ease of synthesis.
More preferably, both ends of the polycondensed ester are —OH groups or are sealed with acetic acid or propionic acid.

  Both ends of the polycondensed ester of the present invention are sealed with acetic acid so that both ends become acetyl ester residues (sometimes referred to as acetyl residues). The cellulose acylate film is preferable from the viewpoint that the handling of the cellulose acylate film is improved and the cellulose acylate film excellent in humidity stability and polarizing plate durability can be obtained.

The number average molecular weight of the polycondensed ester is preferably 500 to 2000, more preferably 700 to 1500, and particularly preferably 700 to 1200. The number average molecular weight of the polycondensed ester is preferably 500 or more from the viewpoint of improving optical expression. Moreover, if it is 2000 or less, compatibility with a cellulose acylate will become high and it will become difficult to produce the bleed-out at the time of film forming and a heat-stretching.
The number average molecular weight of the polycondensed ester of the present invention can be measured and evaluated by gel permeation chromatography. Further, in the case of a polyester polyol having an unsealed terminal, it can also be calculated from the amount of hydroxyl group per weight (hereinafter referred to as hydroxyl value). The hydroxyl value is determined by measuring the amount (mg) of potassium hydroxide required for neutralizing excess acetic acid after acetylating the polyester polyol.
The polycondensed ester according to the present invention can be used as a plasticizer.

  In the cellulose acylate film of the present invention, the content of the polycondensed ester with respect to 100 parts by mass of the cellulose acylate is preferably 5 to 25 parts by mass, more preferably 8 to 20% by mass, Most preferably, it is 15 mass%.

The dicarboxylic acid residue, the diol residue, and the type and ratio of each residue contained in the polycondensed ester used in the present invention can be measured by an ordinary method using H-NMR. Usually, deuterated chloroform can be used as a solvent.
The number average molecular weight of the polycondensed ester can be measured by a usual method using GPC (Gel Permeation Chromatography), and polystyrene can be usually used as a standard material.
For measurement of the hydroxyl value of the polycondensed ester, the acetic anhydride method described in Japanese Industrial Standards JIS K3342 (discontinued) can be applied. When the polycondensate is a polyester polyol, the hydroxyl value is preferably 50 to 190, and more preferably 50 to 130.

  Specific examples of the polycondensed ester are shown in Table 1 below, but the present invention is not limited to the following specific examples.

(Method for synthesizing polycondensed ester)
The polycondensation ester used in the present invention can be synthesized by a conventional method such as a hot melt condensation method using a polyesterification reaction or transesterification reaction between a diol and a dicarboxylic acid, or an interfacial condensation method between an acid chloride of these acids and a glycol. It can be easily synthesized by either method. In addition, the polycondensed ester according to the present invention is described in detail in Koichi Murai, “Plasticizer Theory and Application” (Kokai Shobo Co., Ltd., first edition issued 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.

(Sugar ester compound)
-Sugar residue-
The sugar ester compound refers to a compound in which at least one substitutable group (for example, a hydroxyl group or a carboxyl group) in the polysaccharide constituting the compound and at least one substituent are ester-bonded. . That is, the sugar ester compound referred to here includes a wide range of sugar derivatives, for example, a compound containing a sugar residue such as gluconic acid as a structure. That is, the sugar ester compound includes an ester of glucose and carboxylic acid and an ester of gluconic acid and alcohol.
The substitutable group in the polysaccharide constituting the sugar ester compound is preferably a hydroxyl group.

  The sugar ester compound includes a structure derived from a polysaccharide constituting the sugar ester compound (hereinafter also referred to as a sugar residue). The structure of the sugar residue per monosaccharide is referred to as the structural unit of the sugar ester compound. The structural unit of the sugar ester compound preferably includes a pyranose structural unit or a furanose structural unit, and more preferably all sugar residues are a pyranose structural unit or a furanose structural unit. Further, when the sugar ester is composed of a polysaccharide, it preferably contains both a pyranose structural unit or a furanose structural unit.

  The sugar residue of the sugar ester compound may be derived from 5 monosaccharides or 6 monosaccharides, but is preferably derived from 6 monosaccharides.

  The number of structural units contained in the sugar ester compound is preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2. That is, the sugar constituting the sugar ester compound is preferably a disaccharide to a tetrasaccharide, more preferably a disaccharide to a trisaccharide, and particularly preferably a disaccharide.

  In the present invention, the sugar ester compound is more preferably a sugar ester compound containing 2 to 4 pyranose structural units or furanose structural units in which at least one hydroxyl group is esterified, and at least one of the hydroxyl groups is esterified. More preferably, the sugar ester compound contains two pyranose structural units or furanose structural units.

  Examples of the monosaccharides or saccharides containing 2 to 4 monosaccharide units include, for example, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, fructose, mannose, gulose, idose, galactose , Talose, trehalose, isotrehalose, neotrehalose, trehalosamine, caudibiose, nigerose, maltose, maltitol, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose, melibiose, primebelloose, rutiose , Sucrose, sucralose, turanose, vicyanose, cellotriose, cacotriose, gentianose, isomaltori , Isopanose, maltotriose, manninotriose, melenitoose, panose, planteose, raffinose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, baltopentaose, velval course, maltohexaose , Xylitol, sorbitol and the like.

  Preferably, ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, xylitol, sorbitol, more preferably arabinose, xylose, glucose, fructose, mannose , Galactose, maltose, cellobiose and sucrose, particularly preferably xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, xylitol and sorbitol.

  Preferred examples of the substituent of the sugar ester compound include an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably an alkyl group having 1 to 8 carbon atoms, such as a methyl group, An ethyl group, a propyl group, a hydroxyethyl group, a hydroxypropyl group, a 2-cyanoethyl group, a benzyl group, etc.), an aryl group (preferably having a carbon number of 6 to 24, more preferably 6 to 18 and particularly preferably 6 to 12). A group such as a phenyl group or a naphthyl group, an acyl group (preferably having a carbon number of 1 to 22, more preferably a carbon number of 2 to 12, particularly preferably a carbon number of 2 to 8, such as an acetyl group or a propionyl group, Butyryl group, pentanoyl group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group), amide group (preferred) Or an amide group (preferably 4 to 22 carbon atoms, more preferably an amide having 2 to 12 carbon atoms, particularly preferably an amide having 2 to 8 carbon atoms, such as a formamide group or an acetamide group). May include amide groups having 4 to 12 carbon atoms, particularly preferably 4 to 8 carbon atoms (for example, succinimide group, phthalimide group, etc.). Among them, an alkyl group or an acyl group is more preferable, a methyl group, an acetyl group, a propionyl group, a butyryl group (among them, i-butyryl group is preferable), a benzoyl group is more preferable, and at least one of the acetyl group and the butyryl group is selected. It is particularly preferable to include the acetyl group, and it is particularly preferable to include only the acetyl group or both the acetyl group and the butyryl group.

  Examples of the sugar ester compound used in the present invention include the following compounds. However, the sugar ester compounds that can be used in the present invention are not limited to these. In the following structural formulas, R each independently represents an arbitrary substituent, and a plurality of R may be the same or different.

  Other examples of the sugar ester compound include JP 2001-247717 A, JP 2005-515285 A, International Publication WO 2007/125765, International Publication WO 2009/011228, International Publication WO 2009/031464, and the like. The sugar ester compounds described can also be used.

  As the method for obtaining the sugar ester compound, commercially available products such as those manufactured by Tokyo Chemical Industry Co., Ltd., Aldrich, etc., or known ester derivatization methods for commercially available carbohydrates (for example, Japanese Patent Laid-Open No. Hei. Can be synthesized by carrying out the method described in JP-A-8-245678.

  The sugar ester compound has a number average molecular weight of preferably 200 to 3500, more preferably 420 to 3000, and particularly preferably 450 to 2000.

  The sugar ester compound is preferably contained in an amount of 2 to 35% by mass, more preferably 5 to 20% by mass, and particularly preferably 10 to 15% by mass with respect to the cellulose acylate.

(Optical developer)
The film of the present invention may contain a retardation enhancer in order to develop a retardation value. Although there is no restriction | limiting in particular as said retardation expression agent, What consists of a compound characterized by the structure represented by rod-shaped or a disk-shaped compound, or the general formula (II-1) mentioned later can be mentioned. 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 developer composed of the rod-shaped compound is preferably 0.1 parts by mass or more and less than 3 parts by mass, and 0.5 parts by mass or more and less than 2 parts by mass with respect to 100 parts by mass of the cellulose acylate component. More preferably it is. On the other hand, the discotic compound is preferably 0.1 to 10% by mass, more preferably 0.5 to 4% by mass, and 1 to 3% by mass with respect to the cellulose acylate. Is particularly preferred. A preferable addition amount of the compound having a characteristic in the structure represented by the general formula (II-1) described later to the cellulose acylate is the same as the preferable addition range of the discotic compound.
The compound having the characteristics represented by the discoidal compound and the structure represented by the general formula (II-1) described later is superior to the rod-shaped compound in the Rth retardation expression, and therefore, particularly when a large Rth retardation is required. Is preferably used. 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 hetero ring 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 in the retardation enhancer is preferably 2-20, more preferably 2-12, still more preferably 2-8, and 2-6. Most preferred.
The bonding relationship between two aromatic rings can be classified into (a) when a condensed ring is formed, (b) when directly linked by a single bond, and (c) when linked via 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 the linking group 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 sulfonamide group include a methane sulfonamide group, a butane sulfonamide group, and an n-octane sulfonamide 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.

  In the present invention, it is preferable to use a triazine compound represented by the following general formula (I) as the discotic compound.

In the above general formula (I):
R ²⁰¹ 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 ²⁰¹ each independently represents a single bond or —NR ²⁰² —. Here, each R ²⁰² 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 ²⁰¹ is preferably phenyl or naphthyl, particularly preferably phenyl. The aromatic ring R ²⁰¹ represents may have at least one substituent at any substitutable 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 ^R201 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 ²⁰¹ 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 a n-C ₄ H _9.

The alkyl group represented by R ²⁰² 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 ²⁰² 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 ²⁰² are the same as the aromatic ring and heterocyclic ring represented by R ²⁰¹ , 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 ^R201 .

  The compound represented by the general formula (I) can be synthesized by a known method such as the method described in JP-A-2003-344655. Details of the retardation enhancer are described on page 49 of published technical bulletin 2001-1745.

（一般式（ＩＩ−１）中、Ｙ¹はメチン基、あるいは−Ｎ−を表す。Ｒａ³¹はアルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｒｂ³¹、Ｒｃ³¹、Ｒｄ³¹およびＲｅ³¹はそれぞれ独立に水素原子、アルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｑ²¹は単結合、−Ｏ−、−Ｓ−、あるいは−ＮＲｆ−を示し、Ｒｆは水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、または複素環基を表し、Ｒａ³¹と連結して環を形成してもよい。Ｘ³¹、Ｘ³²、およびＸ³³は、それぞれ独立に単結合または２価の連結基を表す。Ｘ³⁴は、下記一般式（Ｑ）
一般式（Ｑ）

（一般式（Ｑ）中、＊側が前記一般式（ＩＩ−１）で表される化合物中の複素環に置換しているＮ原子との連結部位である。）
で表される２価の連結基からなる群から選択される連結基を表す。） In this invention, it is also preferable to use the compound characterized by the structure represented by the following general formula (II-1) as said discotic compound. In addition, the compound characterized by the structure represented by the following general formula (II-1) does not need to be a disk shape.

(In General Formula (II-1), Y ¹ represents a methine group or —N—. Ra ³¹ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Rb ³¹ , Rc ³¹ , Rd ³¹ and Re ³¹ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and Q ²¹ represents a single bond, —O—, —S— or —NRf—. , Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and may be linked to Ra ³¹ to form a ring, X ³¹ , X ³² , and X ³³ are Each independently represents a single bond or a divalent linking group, X ³⁴ represents the following general formula (Q);
General formula (Q)

(In general formula (Q), the * side is the linking site with the N atom substituted on the heterocyclic ring in the compound represented by general formula (II-1).)
A linking group selected from the group consisting of divalent linking groups represented by )

（一般式（ＩＩ−２）中、Ｙ²はメチン基、あるいは−Ｎ−を表す。Ｒａ³²はアルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｒｂ³²、Ｒｃ³²、Ｒｄ³²はそれぞれ独立に水素原子、アルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｑ²²は単結合、−Ｏ−、−Ｓ−、あるいは−ＮＲｆ−を示し、Ｒｆは水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、または複素環基を表し、Ｒａ³²と連結して環を形成してもよい。Ｘ³⁵は、それぞれ独立に単結合または２価の連結基を表す。Ｘ³⁶は、前記一般式（Ｑ）で表される２価の連結基からなる群から選択される連結基を表す。） The compound represented by the general formula (II-1) is particularly preferably represented by the following general formula (II-2).

(In General Formula (II-2), Y ² represents a methine group or —N—. Ra ³² represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Rb ³² , Rc ³² , Rd ³² each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, Q ²² represents a single bond, —O—, —S—, or —NRf—, and Rf represents Represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and may be linked to Ra ³² to form a ring, each of X ³⁵ being independently a single bond or a divalent linkage .X ³⁶ represents a group represents a linking group selected from the group consisting of divalent linking group represented by the general formula (Q).)

（一般式（ＩＩ−４）中、Ｙ⁴はメチン基、あるいは−Ｎ−を表す。Ｒａ³⁴はアルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｑ²⁴は単結合、−Ｏ−、−Ｓ−、あるいは−ＮＲｆ−を示し、Ｒｆは水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、または複素環基を表し、Ｒａ³⁴と連結して環を形成してもよい。Ｒ⁶¹、Ｒ⁶²、Ｒ⁶³およびＲ⁶⁴は、それぞれ独立に水素原子、ハロゲン原子、水酸基、カルバモイル基、スルファモイル基、炭素数１から８のアルキル基、炭素数１から８のアルコキシ基、炭素数１から８のアルキルアミノ基、炭素数１から８のジアルキルアミノ基を表す。） The compound represented by the general formula (II-1) is particularly preferably represented by the following general formula (II-4).

(In General Formula (II-4), Y ⁴ represents a methine group or —N—. Ra ³⁴ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Q ²⁴ represents a single bond, -O-, -S-, or -NRf-, wherein Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and is linked to Ra ³⁴ to form a ring. R ⁶¹ , R ⁶² , R ⁶³ and R ⁶⁴ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, a carbamoyl group, a sulfamoyl group, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. Represents an alkylamino group having 1 to 8 carbon atoms and a dialkylamino group having 1 to 8 carbon atoms.)

（一般式（Ｅ−５）中、Ｒ⁶⁵、Ｒ⁶⁶、Ｒ⁶⁷およびＲ⁶⁸は、それぞれ独立に水素原子、ハロゲン原子、水酸基、カルバモイル基、スルファモイル基、炭素数１から８のアルキル基、炭素数１から８のアルコキシ基、炭素数１から８のアルキルアミノ基、炭素数１から８のジアルキルアミノ基を表す。Ｒａ³⁵はアルキル基、アルケニル基、アルキニル基、アリール基または複素環基を表す。Ｑ²⁵は単結合、−Ｏ−、−Ｓ−、あるいは−ＮＲｆ−を示し、Ｒｆは水素原子、アルキル基、アルケニル基、アルキニル基、アリール基、または複素環基を表し、Ｒａ³⁵と連結して環を形成してもよい。） The compound represented by the general formula (II-1) is particularly preferably represented by the following general formula (II-5).

(In the general formula (E-5), R ⁶⁵ , R ⁶⁶ , R ⁶⁷ and R ⁶⁸ are each independently a hydrogen atom, halogen atom, hydroxyl group, carbamoyl group, sulfamoyl group, alkyl group having 1 to 8 carbon atoms, carbon Represents an alkoxy group having 1 to 8 carbon atoms, an alkylamino group having 1 to 8 carbon atoms, and a dialkylamino group having 1 to 8 carbon atoms, and Ra ³⁵ represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Q ²⁵ represents a single bond, —O—, —S—, or —NRf—, and Rf represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and is linked to Ra ^35. To form a ring.)

In the general formula (II-5), R ⁶⁵ , R ⁶⁶ , R ⁶⁷ and R ⁶⁸ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. It is particularly preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms.
Ra ³⁵ is an alkyl group, a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms ( For example, a benzene ring or a naphthalene ring group) or a heterocyclic group having 4 to 10 carbon atoms (for example, a pyrrolyl group, a pyrrolidino group, a pyrazolyl group, a pyrazolidino group, an imidazolyl group, a piperazino group, or a morpholino group). A hydrogen atom and an alkyl group having 1 to 8 carbon atoms are more preferable, and an alkyl group having 1 to 4 carbon atoms is particularly preferable.
Q ²⁵ is a single bond, or —O—, —S—, —N (Xa—Rh) —, or —N (Xa—Rh) —Xb— (where Xa and Xb are each independently a single bond or 2 Examples of the divalent linking group each representing a valent linking group and each represented by X ^a and X ^b include —CO—, —COO—, and —CONH—, where Rh is 1 hydrogen atom carbon atom. Represents an alkyl group having 8 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a heterocyclic group having 2 to 10 carbon atoms. Preferred examples of —NH—Xb— include —NH—CO—, —NH—COO—, —NH—CONH—, —NH—SO ₂ —, etc., —NH—CO—, —NH—COO It is more preferable that the divalent linking group is represented by: Is a single bond or —O—, —S—, —NH— or —N (R) — (wherein R is an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms). Is more preferable, and a single bond or —O— is more preferable.

  Specific examples of the optical developing agent are given below, but the present invention is not limited to the following specific examples.

（上記式中におけるＲ¹〜Ｒ³はそれぞれ下記化合物Ｃ−１０１〜Ｃ−１８０におけるＲ¹〜Ｒ³を表す）

(Representing R ¹ to R ³ in R ¹ to R ³ each is the following compound C-101~C-180 in the above formula)

（上記式中におけるＲ²〜Ｒ³はそれぞれ下記化合物Ｃ−１８１〜Ｃ−１９０におけるＲ²〜Ｒ³を表す）

(Representing R ² to R ³ each R ² to R ³ in the following compound C-181~C-190 in the above formula)

（上記式中におけるＲ³は下記化合物Ｄ−１０１〜Ｄ−１１０におけるＲ³を表す）

(R ³ in the above formula represents a R ³ in the following compound D-101~D-110)

(Peeling accelerator)
In the method for producing a cellulose acylate film of the present invention, it is preferable that the polymer solution for a band layer contains a peeling accelerator. With such a configuration, even when the band layer polymer solution has cellulose acylate having a low total acyl substitution degree, the peelability from the support during film formation is good.

The said cellulose acylate laminated film contains 0.01 mass%-20 mass% of organic acids which satisfy | fill the requirements of following (1)-(3) with respect to the said cellulose acylate of the said polymer solution for band layers. preferable.
(1) Includes a structure in which a polyhydric alcohol and a polycarboxylic acid are bonded by forming an ester bond.
(2) The total number of molecules of the polyhydric alcohol and polycarboxylic acid forming the compound is 3 or more.
(3) It has at least one unsubstituted carboxyl group derived from a polyvalent carboxylic acid.

In the organic acid satisfying the above requirements (1) to (3), the detachability from the solution film-forming equipment (metal support when the dope is fluent) can be improved by an unsubstituted carboxyl group, and the present invention. Then, an organic acid satisfying the requirements (1) to (3) can be used as a peeling accelerator.
Further, the unsubstituted carboxyl group adheres to the metal surface of the support, and the polyhydric alcohol part or the hydrophobic group part substituted therewith blocks the metal surface of the support from an oxidizing agent such as oxygen. Compared to organic acids that do not contain a monohydric alcohol moiety or a hydrophobic group moiety substituted therefor, corrosion of the metal can be prevented.
Hereinafter, the organic acid that satisfies the requirements (1) to (3) that can be used as a peeling accelerator in the band layer polymer solution and other peeling accelerators that may be used in combination will be described.

Although it does not specifically limit as polyvalent carboxylic acid used for the organic acid which satisfy | fills the requirements of said (1)-(3), For example, a succinic acid, a citric acid, tartaric acid, diacetyl tartaric acid, malic acid, and adipic acid are preferable.
In the organic acid that satisfies the requirements (1) to (3), the number of polyvalent carboxylic acid molecules is preferably 1 to 20, more preferably 1 to 15, and more preferably 1 to 10. Particularly preferred.

Examples of the polyhydric alcohol used in the organic acid that satisfies the requirements (1) to (3) include adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, , 3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3- Examples thereof include methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, and glycerin. Among these, glycerin is preferable.
Among the organic acids that satisfy the requirements (1) to (3), the number of polyhydric alcohol molecules is preferably 1 to 20, more preferably 1 to 15, and particularly preferably 1 to 10. preferable.

In addition to the polyhydric alcohol and polyvalent carboxylic acid that constitute the organic acid, the organic acid that satisfies the requirements (1) to (3) is a monovalent acid having a substituent having 4 or more carbon atoms. You may have the structure which formed the ester bond with the one part hydroxyl group of this polyhydric alcohol. Specific examples of the monovalent acid having a substituent having 4 or more carbon atoms are given below. The substituent in the monovalent acid having a substituent having 4 or more carbon atoms means R when the monovalent acid having a substituent having 4 or more carbon atoms is represented as RCOOH.
"fatty acid"
Caproic acid, heptylic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, ricinolenic acid, undecanoic acid.
《Alkyl sulfate》
Myristyl sulfate, cetyl sulfate, oleyl sulfate.
《Alkylbenzene sulfonic acid》
Dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid.
《Alkyl naphthalene sulfonic acid》
Sesquibutyl naphthalene sulfonic acid, diisobutyl naphthalene sulfonic acid.
Among these, a monovalent acid having a substituent having 4 or more carbon atoms, which is a fatty acid, is preferable, caprylic acid, lauric acid, stearic acid, and oleic acid are more preferable, and oleic acid is particularly preferable.
In the organic acid satisfying the requirements (1) to (3), the number of molecules of the monovalent acid having a substituent having 4 or more carbon atoms is preferably 0 to 4, and preferably 0 to 3. More preferred is 0-2.

  In the organic acid satisfying the requirements (1) to (3), the total number of molecules of the polyhydric alcohol and the polycarboxylic acid forming the compound is 3 or more, preferably 3 to 30. More preferably, it is ~ 20.

In the organic acid satisfying the above requirements (1) to (3), the ratio of the polyvalent carboxylic acid, the polyhydric alcohol, and the monovalent acid having a substituent having 4 or more carbon atoms is not particularly limited. Two or more unsubstituted hydroxyl groups may remain, or an unsubstituted hydroxyl group may remain.
The organic acid that satisfies the requirements (1) to (3) has at least one unsubstituted carboxyl group derived from a polyvalent carboxylic acid, and has 1 to 40 unsubstituted carboxyl groups derived from the polyvalent carboxylic acid. It is preferable to have 1-30.

  The organic acid satisfying the requirements (1) to (3) may be used alone or as a mixture. In addition, the organic acid satisfying the requirements (1) to (3) may be ionized depending on the case, and may form a salt with any metal ion depending on the case.

Examples of preferred organic acid compounds that satisfy the requirements (1) to (3) used in the present invention are shown below.
Organic acids (partial condensates of organic acids) having the following composition are preferred. An organic acid having the following composition can be prepared using, for example, Poem K-37V manufactured by Riken Vitamin.

The addition amount of the organic acid satisfying the requirements (1) to (3) contained in the band layer polymer solution is 0.01% by mass to 20% by mass with respect to the cellulose acylate in the band layer polymer solution. %, Particularly preferably 0.05% by mass to 10% by mass, and more preferably 0.1% by mass to 5% by mass. In addition, when the organic acid which satisfy | fills the requirements of said (1)-(3) is a mixture as for the addition amount of the organic acid which satisfy | fills the requirements of said (1)-(3), all said (1)-( It means the total amount of organic acid that satisfies the requirement 3).
If the addition amount is 0.01% or more, the polarizer durability improving effect and the peelability improving effect are sufficient.
In addition, even if the addition amount is about 0.001 to 0.01%, improvement in peelability can be expected by combining with a peelability improvement technique such as peeling site cooling of the casting support.
An addition amount of 20% by mass or less is preferable because the organic acid hardly bleeds out at a high temperature and high humidity, and the orthogonal transmittance of the polarizing plate hardly increases.

  In addition to the organic acid that satisfies the requirements (1) to (3), a known peeling accelerator may be added to the band layer polymer solution. As the known peeling accelerator, for example, compounds described in paragraph numbers 0048 to 0069 of JP-A-2006-45497 can be preferably used.

The peeling accelerator is preferably an organic acid, a polyvalent carboxylic acid ester, a surfactant or a chelating agent.
As the polyvalent carboxylic acid ester, the compound described in paragraph No. 0049 of JP-A-2006-45497 can be preferably used.
As the surfactant, compounds described in paragraph numbers 0050 to 0051 of JP-A-2006-45497 can be preferably used.
The chelating agent is a compound capable of coordinating (chelating) a metal ion such as an iron ion or an alkaline earth metal ion such as a calcium ion. 11-190892, JP-A-2000-18038, JP-A-2010-158640, JP-A-2006-328203, JP-A-2005-68246, and JP-A-2006-306969 can be used. .
The total addition amount of all peeling accelerators contained in the band layer polymer solution is 0.01% by mass (100 ppm) to 20% by mass (200000 ppm) with respect to the cellulose acylate in the band layer polymer solution. The ratio is preferably 0.01% by mass (100 ppm) to 15% by mass (150,000 ppm), more preferably 0.01% by mass (100 ppm) to 10% by mass (100,000 ppm). It is particularly preferably from 03% by mass (300 ppm) to 10% by mass (100,000 ppm), and even more particularly preferably from 0.1% by mass (1000 ppm) to 5% by mass (50000 ppm).

[Other additives]
In the polymer solution, in addition to the polycondensed ester, the sugar ester compound, the optical developing agent, and the release accelerator, other low molecular weight additives, matting agents, and the like can be used as appropriate. .

(Low molecular weight additive)
Examples of the low molecular weight additive include an Rth control agent / adjusting agent, a deterioration preventing agent, an ultraviolet ray preventing agent, other plasticizers, 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 may be added by adding a step of adding an additive 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.

  In the polymer solution, a deterioration preventing agent (for example, an antioxidant, a peroxide decomposing agent, a radical inhibitor, a metal deactivator, an acid scavenger, an amine) may be added. The deterioration inhibitors are described in JP-A-3-199201, JP-A-597073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The amount of the deterioration inhibitor added is 0.01 of the solution (dope) to be prepared from the viewpoint that the effect of the addition of the deterioration inhibitor is manifested and that the deterioration inhibitor is prevented from bleeding out on the film surface. It is preferably ˜1% by mass, more preferably 0.01-0.2% by mass. Particularly preferable examples of the deterioration inhibitor include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

  In the polymer solution, a known plasticizer other than the polycondensed ester can be added in order to improve mechanical properties or improve 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 of the amount of cellulose acylate, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

(Matting agent fine particles)
The polymer solution preferably contains fine particles as a matting agent. Examples of fine particles that can be used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Can do. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / L or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / L, more preferably 100 to 200 g / L. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved. A desirable embodiment is described in detail in pages 35 to 36 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention), and the cellulose acylate film of the present invention. It can also be preferably used in the production method.

〔solvent〕
In the method for producing a cellulose acylate film of the present invention, the solvent used in the polymer solution is not particularly limited as long as it is not contrary to the gist of the present invention.
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. A general method means processing at a temperature of 0 ° C. or higher (ordinary temperature or high temperature). The solution can be prepared by 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.). The high concentration solution 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.

A cellulose acylate film can be produced from the prepared cellulose acylate solution (dope) 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. 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 with high-temperature air whose temperature is successively changed from 100 ° C. 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.

(Co-casting)
In the method for producing a cellulose acylate film of the present invention, in the step of forming the polymer solution into a film, a band layer polymer solution containing cellulose acylate and a solvent, and the total acyl group substitution degree as the polymer solution is 1. The core layer polymer solution containing 5 to 2.7 cellulose acylate, the solvent and the additive is multilayer cast on the support simultaneously or sequentially in this order, and the dry film thickness of the core layer polymer solution is It is also preferable to make the thickness larger than the dry film thickness of the polymer solution for band layer.
The cellulose acylate film of the present invention is preferably produced by forming the solution casting film into a simultaneous multilayer casting film by co-casting or a sequential multilayer casting film. It is because it can be set as the film which has a desired retardation value. On the other hand, in some cases, it is also preferable from the viewpoint of thinning the solution casting film to be a single layer casting film.
That is, 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, the methods described in JP-A-61-158414, JP-A-1-122419, JP-A-11-198285 and the like can be applied. Further, it may be formed into a film by casting a cellulose acylate solution from two casting ports. For example, JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, It can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred 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, the film cast on the metal support is peeled off by the first casting port, and the second casting is performed on the side in contact with the metal support surface. Further, a film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. 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 case of single layer casting, it is easy to recover the material produced by casting, and productivity can be improved. On the other hand, in the case of single layer casting, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain the required film thickness. In many cases, this causes a problem such as a fault or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also 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 degrees of substitution. For example, a cellulose acylate film having a configuration of TAC layer / DAC layer / TAC layer can be produced, or a cellulose acylate film having a configuration of DAC layer / TAC layer / DAC layer can be produced. In addition, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate acylate solutions having different additive concentrations such as the plasticizer, ultraviolet absorber, and matting agent. For example, the matting agent can be contained in the band layer in a large amount or only in the band layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the band layer, and may be contained only in the core layer. Also, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the band layer. For example, the band layer contains a low-volatile plasticizer and / or ultraviolet 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 included only in the band layer on the metal support side. Moreover, in order to cool a metal support body by a cooling drum method and to gelatinize a solution, it is also preferable to add more alcohol which is a poor solvent to a band layer than a core layer. The Tg of the band layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the band layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the band layer and the core layer, and the viscosity of the band layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

(Drying process, stretching process)
The method for producing a cellulose acylate film of the present invention includes a step of stretching the film so that the film thickness after stretching is 20 to 65 μm after the polymer solution is formed into a film, and the stretching step includes: The following conditions (1) and (2) are satisfied.
(1) The residual solvent amount A at the start of stretching is 35% by mass to 65% by mass.
(2) The film atmosphere temperature T during stretching is Tg (° C.)-70 (° C.) to Tg (° C.)-30 (° C.).
(However, Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film dried in an unstretched state)
In addition, if the solvent residual amount at the time of peeling of the film from a support body can satisfy | fill conditions (1) at the time of an extending | stretching start, unless it is contrary to the meaning of this invention, it can set arbitrarily. That is, the solvent residual amount at the time of peeling of the film from the support may be set to at least 35% by mass, and even if stretching is started on the film immediately after peeling, the film is further dried after peeling, and the conditions ( You may control to satisfy | fill 1).

  A method for drying a web that 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 preferable. It is preferable that the drying temperature in the said drying process is 100-145 degreeC. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent to be used.

  In the method for producing a film of the present invention, in the step of stretching a film peeled off from a support (hereinafter also referred to as a web), the residual solvent amount A at the start of stretching is 35% by mass to 65% by mass.

The residual solvent amount can be expressed by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass of the web at an arbitrary time point, and N is a mass when the web of which M is measured is dried at 120 ° C. for 2 hours. The more preferable range of the residual solvent amount A at the start of stretching in the web is 35 to 65% by mass, more preferably 35 to 60% by mass, and particularly preferably 35 to 50% by mass. If there is not too little residual solvent amount at the time of extending | stretching, the dimensional change after wet heat aging of the film obtained becomes small, and it is preferable. On the other hand, if there is not too much residual solvent amount at the time of extending | stretching, the peeling nonuniformity at the time of peeling and the damage of the film by the tenter clip at the time of extending | stretching can be suppressed.

The draw ratio is preferably 15% to 60%, more preferably 15% to 40%, and particularly preferably 20% to 35%. Here, extending 15% to 60% in one direction means that the distance between clips and pins supporting the film is in the range of 1.15 to 1.60 times the distance before stretching. Means.
Stretching may be performed in the film transport direction (longitudinal direction), in the direction orthogonal to the film transport direction (transverse direction), or in both directions, but the cellulose acylate film of the present invention is transported in the film. It is obtained by stretching in a direction orthogonal to the direction, and the stretching ratio is preferably 15% to 60% in the direction orthogonal to the transport direction. A more preferable range of the draw ratio in the direction orthogonal to the transport direction is the same as the above range. By setting the draw ratio to 15% or more, Re can be expressed more appropriately. Moreover, haze can be reduced by making a draw ratio into 60% or less.

The film production method of the present invention satisfies the above condition (2), that is, the film atmosphere temperature T during stretching in the stretching step is Tg (° C.)-70 (° C.) to Tg (° C.)-30 (° C.). is there.
However, Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film dried in an unstretched state.
In the present invention, the Tg is measured using the following dynamic viscoelasticity measuring apparatus. After adjusting the cellulose acylate film sample (unstretched) 5 mm × 30 mm of the present invention for 2 hours or more at 25 ° C. and a relative humidity of 60%, a dynamic viscoelasticity measuring apparatus (Vibron: DVA-225 (IT measurement control ( Measured at a gripping distance of 20 mm, a heating rate of 2 ° C./minute, a measurement temperature range of 30 ° C. to 250 ° C., and a frequency of 1 Hz, the vertical axis is the logarithmic axis, the storage elastic modulus, and the horizontal axis is the linear axis When the temperature (° C.) is taken, the straight line 1 is drawn in the solid region and the straight line 2 is drawn in the glass transition region, as the storage elastic modulus shifts from the solid region to the glass transition region. The intersection of the straight line 1 and the straight line 2 when drawn is the temperature at which the storage elastic modulus suddenly decreases and the film begins to soften when the temperature rises, and the temperature at which the film begins to transition to the glass transition region. Dynamic viscoelasticity To.
If necessary, the Tg is the temperature at which the baseline derived from the glass transition of the film begins to change when measured with a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min. It can be obtained as an average value with the temperature returning to the line.
Moreover, the film atmosphere temperature T can measure the temperature in the middle of extending | stretching by installing a thermocouple in the vicinity of the location where the film is conveyed in an extending | stretching zone, and using a commercially available data logger.
The film atmosphere temperature T during the stretching is preferably Tg (° C.)-70 (° C.) or higher, which makes it difficult to break during the stretching. On the other hand, the film atmosphere temperature T during stretching is preferably Tg (° C.) − 30 (° C.) or less from the viewpoint of improving the optical expression per film thickness of the obtained film.
The film atmosphere temperature T during the stretching is preferably Tg (° C) -30 (° C) to Tg (° C) -60 (° C), and Tg (° C) -35 (° C) to Tg (° C)- More preferably, it is 55 (degreeC).
Moreover, it is preferable that the manufacturing method of the film of this invention is extended | stretched in the direction orthogonal to a film conveyance direction at the extending | stretching temperature which satisfy | fills the said conditions (2).

  When the general cellulose acylate is used after satisfying the condition (2), the stretching temperature is preferably 110 to 190 ° C., and more preferably 120 to 150 ° C., for example. The stretching temperature is preferably 120 ° C. or higher from the viewpoint of lowering haze, and 150 ° C. or lower is preferable from the viewpoint of enhancing optical expression (thin film forming).

  In addition, stretching in biaxial directions perpendicular to each other is an effective method from the viewpoint of improving the optical expression of the film, particularly from the viewpoint of increasing the Rth value of the film. The method for producing a cellulose acylate film of the present invention preferably further includes stretching in the film transport direction simultaneously with stretching in the direction perpendicular to the film transport direction or before and after stretching in the orthogonal direction. The draw ratio in the direction parallel to the conveying direction is preferably 1% to 30%, more preferably 3% to 20%, and particularly preferably 5% to 10%.

In this invention, you may extend | stretch to a biaxial direction simultaneously in a extending | stretching process, and may extend | stretch to a biaxial direction sequentially. When extending | stretching to a biaxial direction sequentially, you may change extending | stretching temperature for every extending | stretching in each direction.
By simultaneous biaxial stretching, the haze is increased to some extent, but the optical expression can be further enhanced.
On the other hand, when sequentially biaxially stretching, it is preferable to first stretch in a direction parallel to the film transport direction and then stretch in a direction orthogonal to the film transport direction.
The preferable range of the residual solvent amount at the start of stretching when performing simultaneous biaxial stretching and the residual solvent amount at the start of stretching when performing the sequential stretching is preferable when stretching in a direction perpendicular to the film conveying direction. This is the same as the range of the residual solvent amount at the start of stretching.
A preferable range of the stretching temperature in the case of performing simultaneous biaxial stretching and the preferable range of the stretching temperature in the case of performing the sequential stretching are the same as the preferable range of the stretching temperature in the case of stretching in the direction orthogonal to the film conveying direction.

(Heat treatment)
The manufacturing method of the present invention may be provided with a heat treatment step after the drying step. The heat treatment in the heat treatment step may be performed after completion of the drying step, and may be performed immediately after the stretching / drying step, or may be separately provided only after the winding by a method described later after the completion of the drying step. .

(Take-up)
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 optical film roll obtained as described above, the slow axis direction of the film is preferably ± 2 ° with respect to the winding direction (longitudinal direction of the film), and further within the range of ± 1 °. Preferably there is. 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.

[Characteristics of cellulose acylate film]
The cellulose acylate film of the present invention is produced by the method for producing a cellulose acylate film of the present invention.
The method for producing a cellulose acylate film of the present invention is such that the residual solvent amount A at the start of stretching, the stretching ratio and stretching so that the cellulose acylate film after the stretching step satisfies the following formulas (1) to (5): It is preferable to adjust the film atmosphere temperature T inside.
Formula (1) 20 μm ≦ d ≦ 65 μm
Formula (2) 0.0008 ≦ Re (550) [nm] / d [nm] ≦ 0.003
Formula (3) 0.002 ≦ Rth (550) [nm] / d [nm] ≦ 0.0065
Formula (4) 0% ≦ IH ≦ 0.07%
Formula (5) −0.2% ≦ LMD, LTD ≦ 0.2%
(In the formulas (1) to (5), d is the film thickness, Re (550) is the in-plane retardation at 550 nm, Rth (550) is the retardation in the film thickness direction at 550 nm, and IH is the noise inside. LMD and LTD represent the rate of change in film dimension in the longitudinal direction and the width direction after being subjected to a wet heat treatment for 1 day at 60 ° C. and a relative humidity of 90%, respectively.
Therefore, the cellulose acylate film of the present invention produced by the method for producing a cellulose acylate film of the present invention preferably satisfies the above formulas (1) to (5).
Hereinafter, preferable characteristics of the cellulose acylate film of the present invention will be described.

(Film thickness)
The film thickness of the cellulose acylate film of the present invention satisfies the above formula (1), that is, satisfies 20 to 65 μm.
A film thickness of 20 μm or more is preferable in terms of handling properties when processing into a polarizing plate or the like and curling suppression of the polarizing plate. A film thickness of 65 μm or less is preferable from the viewpoint of thinning. As for the film thickness of the cellulose acylate film of this invention, 25-60 micrometers is more preferable, and 30-55 micrometers is still more preferable.

Even when the cellulose acylate film of the present invention is a laminate formed by multilayer casting, the film thickness of the entire laminate satisfies the above range. In this case, the cellulose acylate film of the present invention includes a core layer thicker than the band layer. Moreover, when the film of this invention has an air layer on the surface on the opposite side of the said core layer further, it is preferable that the said core layer is thicker than the said air layer.
The cellulose acylate film of the present invention has sufficient peelability if the average thickness of the band layer is 0.2% or more and less than 25% of the average thickness of the core layer, or 0.2% or more. , Streak-like unevenness, film thickness non-uniformity or optical property non-uniformity is suppressed, and if it is less than 25%, the optical development of the core layer can be used effectively, and the laminated film has sufficient optical properties. It is preferable from a viewpoint which can be obtained, It is more preferable that it is 0.5 to 15%, It is especially preferable that it is 1.0 to 10%. Further, when the film of the present invention further has the air layer, it is more preferable that the average film thickness of the air layer and the band layer is 0.2% or more and less than 25% of the average film thickness of the core layer. .

(Film retardation)
In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. Rth was measured by making light having a wavelength λ nm incident from a direction inclined + 40 ° with respect to the normal direction of the film with the slow axis in the plane (determined by KOBRA 21ADH) as the tilt axis (rotation axis). A retardation value and a retardation value measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the retardation value measured in the direction. 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.

The cellulose acylate film of the present invention is preferably used as a protective film for a polarizing plate, and can be particularly preferably used as a retardation film corresponding to various liquid crystal modes. The retardation film of the present invention includes the cellulose acylate film of the present invention.
When the cellulose acylate film of the present invention is used as a retardation film, the film of the present invention preferably satisfies the following formulas (11) and (12).
Formula (11): 30 nm ≦ | Re (590) | ≦ 100 nm
Formula (12): 80 nm ≦ | Rth (590) | ≦ 280 nm
(In the formulas (11) and (12), Re (590) and Rth (590) are the retardation value and thickness in the in-plane direction measured with light having a wavelength of 590 nm in an environment of 25 ° C. and a relative humidity of 60%, respectively. Represents the direction retardation value.)
It is more preferable to satisfy the following formula (11 ′) and formula (12 ′).
Formula (11 ′): 40 nm ≦ | Re (590) | ≦ 100 nm
Formula (12 ′): 100 nm ≦ | Rth (590) | ≦ 250 nm
When Re (590) and Rth (590) satisfy the above formulas (11) and (12), they can be more preferably used as a retardation film.

More preferable optical properties of the cellulose acylate film vary depending on the liquid crystal mode.
For VA mode, Re measured at 590 nm is preferably 30 to 200 nm, more preferably 30 to 150 nm, and even more preferably 40 to 100 nm. Rth is preferably 70 to 400 nm, more preferably 100 to 300 nm, and even more preferably 100 to 250 nm.
For TN mode, Re measured at 590 nm is preferably 0 to 100 nm, more preferably 20 to 90 nm, and even more preferably 50 to 80 nm. Rth is preferably 20 to 200 nm, more preferably 30 to 150 nm, and even more preferably 40 to 120 nm.
For the TN mode, an optically anisotropic layer can be coated on a cellulose acylate film having the retardation value and used as an optical compensation film.

The cellulose acylate film of the present invention is characterized by high optical expression per film thickness. Specifically, the cellulose acylate film of the present invention satisfies the following formulas (2) and (3).
Formula (2) 0.0008 ≦ Re (550) [nm] / d [nm] ≦ 0.003
Formula (3) 0.002 ≦ Rth (550) [nm] / d [nm] ≦ 0.0065
Furthermore, the cellulose acylate film of the present invention preferably satisfies 0.0009 ≦ Re (550) [nm] / d [nm] ≦ 0.0025, and 0.001 ≦ Re (550) [nm] / d. It is more preferable to satisfy [nm] ≦ 0.002.
Furthermore, the cellulose acylate film of the present invention preferably satisfies 0.025 ≦ Rth (550) [nm] / d [nm] ≦ 0.006, and 0.03 ≦ Rth (550) [nm] / d. It is more preferable to satisfy [nm] ≦ 0.055.

(Internal haze of film (Hi))
The internal haze of the cellulose acylate film of the present invention is characterized by satisfying the formula (4), that is, 0 to 0.07%. The cellulose acylate film of the present invention having such a configuration can increase the retardation in the front direction when incorporated in a liquid crystal display device. The internal haze of the cellulose acylate film of the present invention is preferably 0.05% or less, and more preferably 0.03% or less. In the present invention, the internal haze was measured using the following method.
A few drops of liquid paraffin are added to the front and back surfaces of the film, and two glass plates with a thickness of 1 mm (micro slide glass product number S9111, made by MATAUNAMI) are sandwiched from the front and back to obtain completely two glass plates. The film was optically adhered, the haze was measured in a state where the surface haze was removed, and the value obtained by subtracting the haze measured by sandwiching only liquid paraffin between two separately measured glass plates was used as the internal haze ( Calculated as Hi). Each haze is measured according to JIS K-6714 using a haze meter “HGM-2DP” {manufactured by Suga Test Instruments Co., Ltd.}.

(Dimensional change rate)
The cellulose acylate film of the present invention satisfies the following formula (5) in the direction of film conveyance and the direction perpendicular thereto at a dimensional change rate of about 24 hours at 60 ° C. and 90% relative humidity.
Formula (5) −0.2% ≦ LMD, LTD ≦ 0.2%
(In Formula (5), LMD and LTD represent the rate of change in the film dimension in the longitudinal direction and the width direction after being subjected to wet heat treatment for 1 day at 60 ° C. and 90% relative humidity, respectively.)
In the present specification, the LMD and LTD are calculated by the following equation (5 ′).
_{LMD = {(L MD '-L} MD 0) / L MD 0} × 100 ≦ 0.5% (5')
LTD = {(L _TD '−L _TD 0) / L _TD 0} × 100 ≦ 0.5% (5 ′)
Wherein L _MD 0 and L _TD 0 is 25 ° C., respectively, represent an MD direction and a length in the TD direction of the film 2 hours or more moisture adjustment under an atmosphere of a relative humidity of 60%, L _TD 'and L _TD' is 60 It represents the length in the MD direction and TD direction of the film after 24 hours at 90 ° C. relative humidity and after 2 hours of humidity control.
When the dimensional change rate of the cellulose acylate film is within the range of the above formula (5), the dimensional change of the film is less likely to occur after aging with heat and heat, so that light leakage when incorporated in a liquid crystal display device can be suppressed. The dimensional change rate is more preferably −0.1 to 0.1%, and particularly preferably −0.05 to 0.05%.

(Configuration of cellulose acylate film)
The cellulose acylate film of the present invention may have a single layer structure or a plurality of layers, but preferably has a single layer structure.

[Phase difference film]
The cellulose acylate film of the present invention can be used as a retardation film. The “retardation film” is generally used for a display device such as a liquid crystal display device, and means an optical material having optical anisotropy, and is synonymous with a retardation plate, an optical compensation film, an optical compensation sheet, and the like. It is. In a liquid crystal display device, a retardation film is used for the purpose of improving the contrast of a display screen or improving viewing angle characteristics and color.
By using the cellulose acylate film of the present invention, a retardation film in which the Re value and the Rth value are freely controlled can be easily produced.

  A plurality of the cellulose acylate films of the present invention can be laminated, or the cellulose acylate film of the present invention and a film outside of the present invention can be laminated to adjust Re and Rth as appropriate and used as a retardation film. . Lamination of the film can be performed using a pressure-sensitive adhesive or an adhesive.

  In some cases, the cellulose acylate film of the present invention may be used as a support for a retardation film, and an optically anisotropic layer made of liquid crystal or the like may be provided thereon to be used as a retardation film.

[Polarizer]
The polarizing plate of the present invention is characterized by having at least one polarizer and the cellulose acylate film of the present invention. When the film of the present invention is used as a protective film for polarizing plate, the protective film for polarizing plate / polarizer / protective film for polarizing plate / liquid crystal cell / protective film for polarizing plate of the present invention / polarizer / protective film for polarizing plate. It can preferably be used in the configuration, or a protective film for polarizing plate / polarizer / protective film for polarizing plate of the present invention / liquid crystal cell / protective film for polarizing plate of the present invention / polarizer / protective film for polarizing plate. 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.

The polarizing plate of the present invention is a polarizing plate having protective films on both sides of the polarizer, and at least one of the protective films is preferably the cellulose acylate film of the present invention. That is, the film of the present invention is preferably used for a protective film for a polarizing plate. As described above, the polarizing plate is preferably formed by laminating and laminating a protective film 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 acylate film and the polarizer is not particularly limited, but can be performed with an adhesive made of an aqueous solution of a water-soluble polymer. The water-soluble polymer adhesive is preferably a completely saponified polyvinyl alcohol aqueous solution.
In particular, a polarizing plate using the 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 liquid crystal display device of the present invention preferably includes a liquid crystal cell and at least one cellulose acylate film of the present invention or at least one polarizing plate of the present invention. Further, it is a liquid crystal display device including a liquid crystal cell and two polarizing plates disposed on both sides thereof, and at least one of the polarizing plates is more preferably the polarizing plate of the present invention.
In the liquid crystal display device of the present invention, it is preferable that the liquid crystal cell is a VA mode or TN mode liquid crystal cell, and that the film of the present invention expresses Re and Rth within the above preferred ranges. Is particularly preferred.
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 (Anti-Ferroelectric Liquid Nyst) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed.

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 (in Japanese Patent Publication No. 176625), and (2) a liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (for MVA mode) in order to enlarge 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) A SURVAVAL mode liquid crystal cell (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. For the lamination to the liquid crystal cell, the film of the present invention is preferably on the VA cell side. The protective film may be a normal cellulose acylate film, and is preferably thinner than the film of the present invention. For example, it is preferably 40 to 80 μm, and examples thereof include, but are not limited to, commercially available KC4UX2M (40 μm manufactured by Konica Capto), KC5UX (60 μm manufactured by Konica Caputo), TD80 (80 μm manufactured by Fuji Film), and the like.

  The present invention will be described more specifically with reference to the following 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 is not limited to the specific examples shown below.

(Preparation of cellulose acylate)
Cellulose acylates having different types of acyl groups and different degrees of substitution described in Table 11 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 Table 11, Ac in the cellulose acylate type represents an acetyl substituent, and Pr represents a propionyl group.

[Examples 1-7, 10-18 and Comparative Examples 1-4]
<Film formation of cellulose acylate film>
Using the cellulose acylate dope shown below, a film was formed by a solution casting method and used for each of Examples and Comparative Examples.

  In addition, unless otherwise indicated in the following Table 11, cellulose acetate was used as the cellulose acylate. Moreover, about various additives, the addition amount with respect to 100 mass parts of cellulose acylates was described.

(Cellulose acylate dope A)
――――――――――――――――――――――――――――――――――――――――
Cellulose acylate resin: Substituents listed in Table 11, those having a degree of substitution 100 parts by mass Additives: those listed in Table 11 Amounts listed in Table 11 (unit: parts by mass)
Dichloromethane 406 parts by mass Methanol 61 parts by mass ――――――――――――――――――――――――――――――――――――――――

In Table 11 below, Ac represents an acetyl group, and Pr represents a propionyl group.
Moreover, the structure of each additive is described below. In Table 10 below, TPA is terephthalic acid, PA is phthalic acid, AA is adipic acid, SA is succinic acid, EG is ethylene glycol, PG is propylene glycol, and OAc is hydroxyl group terminal acetyl. It shows that it was sealed with a group. The mol% of each unit indicates the sum of dicarboxylic acid units and diol units as 100%.

  Cellulose acylate dope A has a matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd., secondary average particle size of 1.0 μm or less) as 0.13 parts by mass with respect to 100 parts by mass of cellulose acylate. The matting agent dispersion was mixed and stirred.

(Solution casting in a single layer)
The dope having the above composition was put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a cellulose acylate dope. The dope was cast with a band casting machine. The band was made of SUS. It peeled off from the band in the state whose residual solvent amount is 10-30 mass% more than the residual solvent amount before extending | stretching.
The film peeled off from the band was dried in the tenter device by using a tenter device that clips and conveys both ends of the web with a clip. At this time, the film peeled off from the band separately from the film subjected to the following stretching step was completely dried in an unstretched state to obtain a cellulose acylate film for a Tg measurement sample. It measured by the method as described in a specification, and described as film Tg in the following Table 11.
On the other hand, the drying time and temperature of the film after drying are adjusted so that the residual solvent amount A at the start of stretching becomes the value described in Table 11 below, and the tenter during stretching is installed by the tenter. The film was stretched in the draw ratios and directions described in Table 11 below while applying hot air so that the atmospheric temperature T of the sample became the temperature described in Table 11 below. In addition, it was confirmed that the solvent remained in the stretched film.
Thereafter, the film was transferred from tenter conveyance to roll conveyance, and further dried at 120 to 150 ° C. and wound up. The film thickness at this time is shown in Table 11 below.

[Examples 8 and 9]
(Solution casting with co-casting with release agent layer, solution casting with different cotton co-casting)
In Example 8, as in the cellulose acylate dope A in Example 1, the dope for the core layer was prepared using the cellulose acylate having the total substitution degree described in Table 11 below and the additive. Using a cellulose acylate with the same total substitution degree as the cellulose acylate in the core layer dope as a band layer dope, adding a solvent and a matting agent in the same manner as the core layer dope, and further condensing as a peeling accelerator A solution to which body A-2 (trade name Poem K-37V, manufactured by Riken Vitamin Co., Ltd.) was added was prepared. As the air layer dope, a solution containing only the cellulose acylate having the same total substitution degree as the cellulose acylate in the core layer dope and a solvent was prepared. As shown in FIG. 1, these three kinds of dopes were cast together from a casting die 89 on a traveling casting band 85. Here, the core layer is made thickest by adjusting the casting amount of each dope. As a result, the film thickness after stretching is the total film thickness of the thickness, band layer and air layer described in Table 3 below. Simultaneous multi-layer co-casting was performed so that each thickness was 2.5 μm to form a cast film. Thereafter, a cellulose acylate film of Example 8 was produced in the same manner as in Example 1 under the production conditions described in Table 11 below.
In Example 9, the cellulose acylate used in the band layer dope and the air layer dope in Example 8 was changed to cellulose acetate having a total substitution degree of 2.82, and a stripping accelerator was added to the band layer dope. A simultaneous multilayer co-casting was performed in the same manner as in Example 8 except that the cast film was not formed, thereby forming a cast film. Thereafter, a cellulose acylate film of Example 9 was produced in the same manner as in Example 1 under the production conditions described in Table 11 below.

[Comparative Example 5]
A cellulose acylate film having a thickness of 70 μm was produced according to the method described in Example 11 of JP2010-250298A. In addition, about the additive used by the comparative example 5, it described in the said Table 10 as additive P-64.

[Evaluation]
(Measurement of retardation value)
The produced cellulose acylate film was conditioned for 2 hours or more at 25 ° C. and a relative humidity of 60%, and was measured at 25 ° C. and a relative humidity of 60% using a birefringence measuring device (KOBRA 21ADH, manufactured by Oji Scientific Instruments). Table 11 shows the Re value and Rth value measured at 590 nm. In addition, values of Re (nm) and Rth (nm) per film thickness (μm) were calculated and are shown in Table 11 together.

(Internal haze)
The internal haze is measured by dropping several drops of glycerin on both sides of the cellulose acylate film sample 40 mm × 80 mm of the present invention, and two glass plates (MICRO SLIDE GLASS part number S9213, manufactured by MATSANAMI) from both sides. In a sandwiched state, glycerin was added between two glasses from a haze value measured according to JIS K-6714 using a haze meter “HGM-2DP” {manufactured by Suga Test Instruments Co., Ltd.] at 25 ° C. and a relative humidity of 60%. The value (%) obtained by subtracting the haze measured in a state where several drops were dropped was defined as the internal haze. The results are shown in Table 2 below.

(Dimensional change rate)
The dimensional change rate of the sample film after 90 hours at 60 ° C. and 90% relative humidity, that is, a value of (L′−L0) / L0} × 100% was determined in the film transport direction and the direction orthogonal thereto. Here, L0 represents the film length (unit: mm) before passing for 24 hours at 60 ° C. and 90% relative humidity, and L ′ is further 2 hours after passing for 24 hours at 60 ° C. and 90% relative humidity. The film length (unit: mm) after conditioning. The sample film used was 30 mm × 120 mm, and other conditions were as follows.
After conditioning for 2 hours or more in an atmosphere of 25 ° C. and relative humidity 60%, automatic pin gauges (manufactured by Shinbun Kagaku Co., Ltd.) are used to open 6 mmφ holes at 100 mm intervals so that they are parallel to the 120 mm side of the film. , The original size (L0) of the interval is measured to a minimum scale of 1/1000 mm. After 24 hours at 60 ° C. and a relative humidity of 90%, after adjusting the humidity for 2 hours in an atmosphere of 25 ° C. and a relative humidity of 60%, the dimension L ′ of the punch interval is measured.
The obtained results are shown in Table 11 below.

From Table 11, it was found that the cellulose acylate films of each Example had high optical development properties, low internal haze, and small dimensional change after wet heat aging.
On the other hand, the cellulose acylate film of Comparative Example 1 was produced using a cellulose acylate having a total acyl substitution degree exceeding the upper limit of the range of the present invention, and the obtained film was Re / d and Rth / d. Was small.
The cellulose acylate film of Comparative Example 2 was produced by stretching under a condition that the residual solvent amount A before stretching was below the lower limit of the range of the present invention, and the obtained film had a large dimensional change after wet heat aging. It was.
The cellulose acylate film of Comparative Example 3 was produced by stretching under a condition that the residual solvent amount A before stretching exceeds the upper limit value of the range of the present invention, and the obtained film was unevenly peeled, resulting in a tenter. The film characteristics could not be measured because a hole was formed in the clip biting portion of the apparatus.
The cellulose acylate film of Comparative Example 4 was produced by stretching under conditions where the atmospheric temperature T during stretching was lower than the lower limit of the range of the present invention, and the resulting film was broken during stretching. The film properties could not be measured.
The cellulose acylate film of Comparative Example 5 was produced by stretching under conditions where the film thickness exceeded the upper limit of the range of the present invention, and the obtained film was found to have low optical developability per film thickness. It was.

(Preparation of polarizing plate)
A polarizer was produced by adsorbing iodine to a stretched polyvinyl alcohol film.
The cellulose acylate films of each Example and Comparative Example were saponified and attached to one side of the polarizer using a polyvinyl alcohol adhesive. The saponification treatment was performed under the following conditions. A 1.5 mol / L aqueous sodium hydroxide solution was prepared and kept at 55 ° C. A 0.005 mol / L dilute sulfuric acid aqueous solution was prepared and kept at 35 ° C. The produced cellulose acylate film was immersed in the aqueous sodium hydroxide solution for 2 minutes, and then immersed in water to thoroughly wash away the aqueous sodium hydroxide solution. Subsequently, after being immersed in the above-mentioned dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
A commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is saponified, and is attached to the opposite side of the polarizer using a polyvinyl alcohol adhesive and dried at 70 ° C. for 10 minutes or more. did. It arrange | positioned so that the transmission axis of a polarizer and the slow axis of the cellulose acylate film of each Example and comparative example which performed the saponification process above may become parallel. The transmission axis of the polarizer and the slow axis of the commercially available cellulose triacylate film were arranged so as to be orthogonal.
The produced polarizing plate was made into the polarizing plate of each Example and a comparative example.

(Mounting on liquid crystal display devices)
The front and back polarizing plates and retardation plates of a VA mode liquid crystal TV (LC-46LX1, manufactured by SHARP) were peeled off and used as a liquid crystal cell. As the viewing-side polarizing plate and the backlight-side polarizing plate of the liquid crystal display device using the vertical alignment type liquid crystal cell described above, both the polarizing plates of the examples, the comparative examples, and the polarizers are commercially available cellulose triacylate films ( A polarizing plate of Fujitac TD80UF, manufactured by Fuji Film Co., Ltd. was installed. The viewing side polarizing plate and the backlight side polarizing plate were attached to the liquid crystal cell via an adhesive. The crossed Nicols were arranged so that the transmission axis of the viewing side polarizing plate was in the vertical direction and the transmission axis of the backlight side polarizing plate was in the left and right direction.
The produced liquid crystal display device was used as the liquid crystal display device of each example and comparative example.
Using a measuring instrument (BM5A, manufactured by TOPCON), in the dark room, the brightness values of the black display and the white display in the panel front direction of the liquid crystal display devices of the examples and comparative examples were measured, and the front contrast (white brightness / black) The luminance was calculated and all showed good performance.

70 Casting film 85 Casting band 86a Rotating roller 89 Casting die 120 Core layer dope 121 Air layer dope 122 Band layer dope 120a Core layer 121a Air layer 122a Band layer t1 Core layer thickness t2 Air layer layer thickness t3 Band Layer thickness

Claims (13)

Forming a polymer solution containing cellulose acylate having a total substitution degree of 1.5 to 2.7, a solvent and an additive into a film;
Including a step of stretching the film so that the film thickness after stretching is 20 to 65 μm,
The method for producing a cellulose acylate film, wherein the stretching step satisfies the following conditions (1) and (2).
(1) The residual solvent amount A at the start of stretching is 35% by mass to 65% by mass.
(2) The film atmosphere temperature T during stretching is Tg (° C.)-70 (° C.) to Tg (° C.)-30 (° C.).
(However, Tg represents the glass transition temperature (unit: ° C.) of the cellulose acylate film dried in an unstretched state) The stretching step includes stretching in a direction perpendicular to the film conveyance direction,
The method for producing a cellulose acylate film according to claim 1, wherein a draw ratio in a direction perpendicular to the film conveying direction is 15% to 60%.   The method for producing a cellulose acylate film according to claim 2, comprising stretching in the film transport direction simultaneously with stretching in the direction perpendicular to the film transport direction or before and after stretching in the orthogonal direction.   The method for producing a cellulose acylate film according to any one of claims 1 to 3, wherein the polymer solution contains a polycondensation ester or a sugar ester as the additive.   The cellulose acylate according to any one of claims 1 to 4, wherein the content of the additive in the polymer solution is 5% by mass to 25% by mass with respect to the cellulose acylate. A method for producing a film. The residual solvent amount A at the start of stretching, the stretching ratio, and the film atmosphere temperature T during stretching are adjusted so that the cellulose acylate film after the stretching step satisfies the following formulas (1) to (5). The manufacturing method of the cellulose acylate film as described in any one of Claims 1-5.
Formula (1) 20 μm ≦ d ≦ 65 μm
Formula (2) 0.0008 ≦ Re (550) [nm] / d [nm] ≦ 0.003
Formula (3) 0.002 ≦ Rth (550) [nm] / d [nm] ≦ 0.0065
Formula (4) 0% ≦ IH ≦ 0.07%
Formula (5) −0.2% ≦ LMD, LTD ≦ 0.2%
(In the formulas (1) to (5), d is the film thickness, Re (550) is the in-plane retardation at 550 nm, Rth (550) is the retardation in the film thickness direction at 550 nm, and IH is the noise inside. LMD and LTD represent the rate of change in film dimension in the longitudinal direction and the width direction after being subjected to a wet heat treatment for 1 day at 60 ° C. and a relative humidity of 90%, respectively.   In the step of forming the polymer solution into a film, a polymer solution for a band layer containing cellulose acylate and a solvent, and a cellulose acylate and a solvent having a total acyl group substitution degree of 1.5 to 2.7 as the polymer solution And a core layer polymer solution containing an additive in this order simultaneously or sequentially on a support, and the dry film thickness of the core layer polymer solution is greater than the dry film thickness of the band layer polymer solution. The method for producing a cellulose acylate film according to claim 1, wherein the thickness is also increased.   The method for producing a cellulose acylate film according to claim 7, wherein the band layer polymer solution contains a peeling accelerator.   The method for producing a cellulose acylate film according to claim 7, wherein the total substitution degree of the cellulose acylate in the polymer solution for the band layer exceeds 2.7.   A cellulose acylate film produced by the method for producing a cellulose acylate film according to claim 1.   A polarizing plate comprising a polarizer and at least one cellulose acylate film according to claim 10.   A liquid crystal display device comprising a liquid crystal cell and at least one cellulose acylate film according to claim 10 or at least one polarizing plate according to claim 11.   The liquid crystal display device according to claim 12, wherein the liquid crystal cell is a VA mode liquid crystal cell.

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